My Weekend Forecast ( May 7-9 )

The Storm Prediction Center Has Issued A Marginal Risk For Severe Thunderstorms Later Today-Tonight For Locations Along & North To Northwest Of The Cumberland Mountains

Overnight Into Saturday Morning

Partly cloudy.  WNW-NW winds 5-10 mph, with higher gusts, along mountain ridges and plateaus below 2700 feet.   Winds WNW-N 10-15 mph, with higher gusts, on mountain ridges above 2700 ft.  Temperatures in the 40s to around 50 degrees, except dropping into the 30s in colder mountain valleys ( especially along and north of High Knob Massif ).

Saturday Afternoon

Partly cloudy & warmer.  Chance of a hit-miss shower or thunderstorm.  Becoming gusty.  WSW-W winds 10-20 mph with higher gusts.  Temperatures varying from 60s in upper elevations to the mid-upper 70s to around 80 degrees.

Saturday Night Into Sunday Morning

A chance for showers & thunderstorms.  Some storms could be strong to locally severe ( prolific lightning & damaging winds being the greatest threats ).  W-NW winds 10-20 mph, with higher gusts, along mid-upper elevation mountain ridges-plateaus.  Temperatures widespread in the 50s.

Sunday Afternoon

Partly to mostly cloudy.  Chance of a hit-miss shower or thunderstorm.  NW winds 5-10 mph, decreasing late and becoming variable to Easterly.  Temperatures varying from the 60s to the lower-middle 70s.

Sunday Night Into Monday Morning

Partly to mostly cloudy.  Winds becoming SSW-SW at 5-15 mph along middle elevation ridges-plateaus.  Winds SW-W 10-20 mph, with higher gusts, along upper elevation ridges.  Temperatures varying from the 40s to lower 50s in valleys to the 50s to lower 60s across exposed mid-upper elevation mountain ridges & plateaus.

A rather active and stormy pattern looks to dominate much of next week, with occasional rounds of showers & thunderstorms.

Weather Discussion ( May 6-9 )

From cold and blustery weather the pattern is now shifting back into late spring mode with warmer air poised to spread across the mountain region this weekend.

*The greatest snowfall reports during recent days featured 3.7″ on Mount LeConte and 3.5″ in Mount Mitchell State Park, both sites being above 6000 feet.  A total of 3.0″ was reported on Beech Mountain.  Only a trace of snow occurred atop the typically snowy locations of the High Knob Massif and Snowshoe Mountain ( at 4850 feet ).  The coldest air aloft passing south across the Great Smokies and southern Blue Ridge.

The focus now shifts back to May flowers & showers, with the Storm Prediction Center recently including much of southwestern Virginia within a marginal risk for severe thunderstorm development from late today into Sunday morning ( with WNW to ESE storm motion ).

This is in basic agreement with the latest European Model forecast, with higher storm chances from central-northern Wise County across Dickenson-Buchanan counties than across Scott & Lee counties.

The NAM Model group is a bit farther southwest, but clearly also shows a bias toward better coverage-chances toward the northeast verses southwest in far southwest Virginia.

Thunderstorms look to develop over western and central Kentucky during Saturday afternoon, and to spread east to southeast Saturday night into Sunday morning.  It will be a very close call for this year’s Kentucky Derby, as to whether storms will impact the race or not.

While mean storm trajectories, via the mean flow field, will favor a E to ESE motion, outflow boundaries that interact with terrain features across central-eastern Kentucky could allow for storm development to build SE-S ( with new development often favored on the inflow side ).

Thus, all of the VA-KY border counties will need to be alert for the possibility of thunderstorms impacting any given location ( as well as parts of northeastern-eastern TN ).

As always, stay tuned to NOAA Weather Radio for any possible watches and/or warnings that may be needed from late Saturday Into Saturday Night-Sunday AM.

My Forecast For May 5-7

Unseasonably cold weather, for May, will continue into Friday.  Any snow accumulations are expected to be above 4000 to 4500 feet and mainly restricted to highest peaks from the Smokies to Mount Rogers.

*Colder mountain valleys could drop into the 30s the next few nights, with frost possible if skies can become partly to mostly clear and winds light ( Friday AM and/or Saturday AM having better chances for partial clearing than Thursday AM ). 

Overnight Into Thursday Morning

Colder.  Chance of drizzle or light rain showers ( mixed at highest elevations ).  Dense fog becoming freezing fog at highest elevations.  WNW-NW winds 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges-plateaus.  Temperatures varying from upper 20s to lower 30s at the highest elevations in the High Knob Massif to the upper 30s to lower 40s.  Wind chills in the 20s and 30s along mountain ridges, with 10s in gusts on the highest peaks ( some rime formation possible along the highest ridges-peaks ).

Thursday Afternoon

Mostly cloudy.  Chance of rain showers, especially by late, mixed with snow at highest elevations.  Local sleet or small hail possible at lower-middle elevations.  Chilly for May.  WNW to NW winds at 5 to 15 mph, with higher gusts.  Temps varying from 30s across upper elevations to the 40s to around 50 degrees ( milder south toward the Tri-Cities ).  Wind chills in the 20s and 30s.

Thursday Night Into Friday Morning

Chance of rain showers in the evening ( possibly mixed with snow on highest peaks ).  Partly to mostly cloudy overnight with chance of a shower.  WNW-NW winds 5-15 mph, with higher gusts, below 2700 feet.  NW to N winds 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from low-mid 30s to the low-middle 40s.  Wind chills in the 20s and 30s, except 10s in gusts along highest ridges.

Friday Afternoon

Mostly cloudy.  Continued chilly.  Chance of rain showers.  Winds NW-NNW at 10-20 mph, with higher gusts, along middle-upper elevation ridges & plateaus.  Temperatures varying from the 40s to mid-upper 50s.  Wind chills in the 30s and 40s ( coldest at the highest elevations ).  Warmer south toward the Tri-Cities.

Friday Night Into Saturday

Mostly cloudy during the evening.  Chance of a showers.  Then becoming partly cloudy overnight.  WNW-NW winds 5-10 mph, with higher gusts, along mountain ridges and plateaus below 2700 feet.   Winds WNW-NW 10-15 mph, with higher gusts, along mountain ridges above 2700 ft.  Temperatures in the 40s to around 50 degrees, except dropping into the 30s in colder mountain valleys if skies become partly cloudy.

Showers & thunderstorms will become possible as warmer air returns this weekend, displacing the cold, Canadian air mass moving into the region Thursday.

Weather Discussion ( May 4-7 )

Rain became mixed with wet snow at highest elevations in the High Knob Massif during Wednesday Night, with big flakes falling but not sticking ( temp in mid 30s ).

Temperatures as of 5:00 AM on Thursday ( May 5 ) have fallen to around freezing atop the High Knob Massif and Black Mountain, with much colder wind chill factors ( in the 10s to lower 20s amid northerly wind gusts in cap clouds…DENSE FOG ).

While it is too early for Blackberries to bloom, Dewberries are in bloom…so maybe this is Dewberry Winter!

Due to very cold air aloft, clouds will be abundant by day into Friday with chances for showers ( mixed with snow within highest elevations above 3500-4000 feet and all snow above 5000-5500 feet ).  Small hail or sleet will continue to be possible with some of the showers.

Note the puffy, vertically stacked clouds, with cold air aloft.  Any sunshine during Thursday and Friday will tend to develop clouds, due to rapid drops in temperature with increasing elevation.  At night; however, there will be a chance for clouds to break.  If clearing should occur it would allow temps to become colder in mountain valleys with readings dropping into the 30s.  Currently, the best chances for this would be Friday AM and/or Saturday AM as the Upper Low moves farther east.  A frost or local freeze risk could arise in colder valleys if skies clear for a prolonged period.

Precipitation beneath upper lows can be tricky, with the latest NAM 12 KM Model run forecasting heaviest amounts to remain east of the Cumberland Mountains and southern Appalachians ( in general ) today into Friday ( above ).

Rainfall increases with warm air advection showers and thunderstorm development into this weekend along and west of the Appalachians ( below ).

Keep Warm Amid This Dewberry Winter!

My Forecast For Today ( May 3-5 )

Very cold air aloft will support the development of numerous showers & thunderstorms, especially from late Tuesday into Thursday.  Many will be capable of producing hail.  As cold air deepens some snow and sleet will become possible by Wednesday Night into Thursday, especially across upper elevations.

*Some accumulation of snow-sleet will be possible above 3500 feet into Thursday Morning as unseasonably cold air, and wind chills, impacts the mountain region.  Some mix of wintry precipitation will be possible at lower-middle elevations.

Overnight Into Tuesday Morning

A chance of rain showers.  Areas of dense fog at highest elevations and in places that had heavy Monday rainfall.  Winds shifting WNW-NW at 5-15 mph along middle-upper elevation mountain ridges into morning.  Temperatures dropping into the 40s to middle-upper 50s ( coolest along highest mountain ridges ).

Tuesday Afternoon

Mostly cloudy.  Cooler.  A chance of showers.  Local thunder possible.  WNW-NW winds at 5-10 mph, with higher gusts.  Temps varying from upper 40s to lower 50s at highest elevations to the middle to upper 60s.

Tuesday Night Into Wednesday Morning

Mostly cloudy.  Chilly.  A chance of showers.  Local thunder & small hail possible.  W-NW winds generally less than 10 mph below 2700 feet.  W-NW winds 5-15 mph, with higher gusts, on mountain ridges above 2700 feet.  Temperatures varying from upper 30s to lower 40s at highest elevations to the mid 40s to around 50 degrees.

Wednesday Afternoon

Partly to mostly cloudy.  A chance of showers and hail producing thunderstorms.  SW-W winds at 5-15 mph, with higher gusts.  Temperatures varying from the 40s to lower 50s at highest elevations to the middle-upper 60s ( warmest at lower elevations and south toward the Tri-Cities ).

Wednesday Night Into Thursday Morning

A chance of showers and hail producing thunderstorms during the evening.  Rain showers becoming mixed with and changing to snow-sleet overnight into morning in the upper elevations ( mixed precipitation possible in middle to lower elevations ).  WNW-NW winds 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges-plateaus.  Temperatures varying from upper 20s to lower 30s at the highest elevations in the High Knob Massif to the upper 30s to lower 40s.  Wind chills in the 20s and 30s along mountain ridges, with 10s in gusts on the highest peaks ( some rime formation possible along the highest ridges-peaks ).

Weather Discussion ( May 2-5 )

The stormy weather pattern that has opened May will be continuing through coming days, with forces driving this storminess shifting toward instability based cold air aloft.

Increasingly cold air aloft will begin to deepen in the vertical during coming days, with a large lapse rate or difference between surface layers and altitudes above 15,000 feet within the atmosphere, where air temps will plunge to -10 to -20 degrees ( Fahrenheit ) below zero.

This pattern is simply straight out of winter, with only modification by the time of year ( e.g., high May sun angles, longer days, warmer ground temperatures and low-level moisture via evaporation and transpiration ) working to ease some of the pain of a late season cold blast.

During May a setting analogous to the heart of winter creates other complicating factors, namely it enhances instability driven by increasingly cold air aloft and lapse rates ( differences in temperature between surface layers and altitudes above 10,000 to 20,000 feet in the free air ).

Numerous showers and thunderstorms will become possible as this instability increases, with many being capable of producing hail as the freezing level aloft drops.  Past settings like this have occasionally generated copious amounts of small to medium size hail.  A spring example being April 15 in 1998 when VDOT snow plows had to be called out for 3-4″ hail depths on routes such as U.S. 23 and State Route 80.

At a time of year when gorgeous spring ephemeral wildflowers are part of the main show, such a late season blast of cold air might seem unheard of; however, it is actually rather common ( and over the long-term locally gave rise to a May 10 spring planting rule…not to plant tender vegetation prior to this time due to cold air ).

At times the cold air blasts can be substantial enough to support snow, with May falls of snow recently being documented during May 1989 ( 2-4″+ ) and May 1992 ( 2″ up to 2-3 feet ).  May snow flakes being most recently observed during May 2005.

 It is too early to know what night or nights will be most favorable for valley frost, but an early estimate would be following the break-down of the northerly-northwest low-level flow into the upslope side of the mountains by late Thursday into Friday morning.  Stay tuned for updates.

My Updated Forecast ( April 30-May 3 )

ALERT For Heavy Rainfall With Strong To Severe Thunderstorms Monday Afternoon Into Monday Night

*The Storm Prediction Center Has Issued A Severe Thunderstorm Watch Effective Until 10:00 PM Monday

In addition, due to heavy weekend rains the threat for rapid rises along streams and flooding of low lying, poor drainage locations needs to be respected.  Please turn around, don’t drown if encountering a water covered roadway.

Saturday Afternoon

Cloudy & cool with light rain & drizzle.  Thunder possible, especially south to southeast of the High Knob Massif and Tennessee Valley Divide.  Northerly winds 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges and plateaus.  Temps in the 50s to mid 60s along and north of the High Knob Massif-Tennessee Valley Divide, with 70s to lower 80s to the south and southeast.

Saturday Night Into Sunday Morning

Showers & thunderstorms becoming likely.  Some storms may be strong.  Downpours possible.  Winds becoming SSE to SSW at 5 to 15 mph, with higher gusts, below 2700 feet.  Winds SSW to SW at 10 to 20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures mainly in the 50s and 60s ( coolest at highest elevations ).

Sunday Afternoon

A chance of hit-miss showers & thunderstorms.  Winds SSW-SW at 5-15 mph, with higher gusts.  Temperatures varying from 60s across upper elevations to the 70s to around 80 degrees ( warmest at lower elevations ).

Sunday Night Into Monday

A chance of showers.  Thunder possible.  Winds SSW to SW at 5-15 mph, with higher gusts, along mountain ridges and plateaus below 2700 feet.  Winds SW-WSW 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temps in the 50s to lower 60s.

Monday Afternoon

Mild & humid with showers & thunderstorms developing.  Some storms may be strong to severe with torrential rain and strong winds-hail.  Winds SSW to SW 5-10 mph, with higher gusts.  Temperatures varying from the 60s across upper elevations to the mid-upper 70s in lower elevations.

Monday Night Into Tuesday Morning

Showers & thunderstorms.  Rainfall may be heavy at times.  Thunderstorms may be strong to severe during the evening.  Winds shifting WNW-NNW at 5-15 mph into the overnight and morning.  Temperatures dropping into the 40s to mid-upper 50s ( coolest along high mountain crestlines ).

Weather Discussion ( April 30-May 3 )

An update on this Monday ( May 2 ) is for the threat of strong-severe thunderstorm development and heavy rainfall, especially for counties along and west of the Virginia-Kentucky stateline & Cumberland Mountains.

Rainfall totals reached 1.00″ to 2.00″ in many places along the Virginia-Kentucky border during the weekend, with training storms having already developed over the foothills of eastern Kentucky on this Monday afternoon.  An eastward propagation during the afternoon will need to be closely followed.

Brief showers already observed Monday in Clintwood have been pounding with large drops and fast fall rates ( often a signal that the atmosphere is primed for torrential rainfall production ).

Severe thunderstorms just brushed the Clintwood area late Sunday, with Summer Salyers reporting dime size hail and moderate rainfall north of town in the Skeetrock community.  Very large hail fell along portions of Pine Mountain into the Hurley area of Buchanan County.

Rainfall Totals Observed May 1 to 9:00 AM on May 2

Clintwood 1 W: 1.35″
( 3.48″ since April 1 )

Upper Norton Reservoir: 1.33″
( 6.69″ since April 1 )

City of Norton Water Plant: 1.15″
( 4.17″ since April 1 )

Coeburn Water Treatment Plant: 1.12″
( 4.69″ since April 1 )

The month of April was atypically dry.  During only 24-36 hours, rainfall at the beginning of May was 63% as much in Clintwood, one of the drier locations, as observed during all of April.

An update on this Saturday is to account for a northerly wind shift into the Cumberland Mountains that has kept temperatures in the 50s ( highest elevations ) and 60s to generate a large north-south difference across the region.

Saturday PM temperatures reached 80 degrees or higher in parts of the Tennessee Valley verses only 50s above 3000 feet across the High Knob Massif, with low-mid 60s in Norton-Wise & Clintwood amid development of light rain and drizzle.

The best chance for any thunder through the remainder of this afternoon will be south & southeast of the Cumberland Mountains, before a wind shift back toward the SSE-SSW will allow more unstable air to come northward tonight into Sunday.

The Storm Prediction Center maintains a marginal risk for severe thunderstorm development through Sunday.

The strongest storms this afternoon remain far to the south over the Dixie States and Gulf Coast.

Forecast model runs today are cranking out heavy rainfall amounts, but timing and placement of heaviest rains does remain in question.

The NAM Model group is forecasting the heaviest rains to develop tonight into Sunday morning.

The Saturday AM run of the European Model is most bullish with a surge of heavy rain and storms by late Monday into Tuesday, with the GFS Model somewhat in the middle but generally closer to the NAM with heaviest amounts being predicted for tonight into Sunday.

The RLX NWSFO ( Charleston, WV ) has issued a Flood Watch for most of their coverage area through Sunday.

Clearly, models are showing the potential for heavy rainfall but timing and placement differences are raising questions as to when and where this will occur.  This continues to be one of the driest spring’s on record, which also remains a factor in any heavy rain forecasts.

Stay tuned to NOAA Weather Radio for any additional watches and/or warnings that may be needed through the next few days.

My New Forecast ( April 26-28 )

Showers & Thunderstorms Will Become Likely By Late Tuesday Into Tuesday Night.  Some Storms Could Be Strong To Locally Severe ( A Marginal Risk Has Been Issued By The Storm Prediction Center )

Overnight Into Tuesday Morning

Partly to mostly clear.  Winds SSW-SW 5-15 mph, with higher gusts, along middle elevation ridges-plateaus at elevations below 2700 feet.  Winds SW-WSW 10-20 mph, with higher gusts, along mountain ridges above 2700 ft.  Mild with temperatures varying from the 50s to lower 60s on exposed mountain ridges-plateaus to the 40s to lower 50s within mountain valleys.

Tuesday Afternoon

Partly to mostly cloudy.  Unseasonably warm.  Increasing humidity and haze.  A chance of showers & thunderstorms by mid-late afternoon.  Winds SSW-WSW at 5-15 mph, with higher gusts.  Temperatures varying from 60s to lower 70s at upper elevations to the lower-middle 80s ( warmest at low elevations of the Russell Fork & Levisa Fork basins ).

Tuesday Night Into Wednesday Morning

Showers & thunderstorms likely.  Some storms may be strong to locally severe.  Downpours are possible.  Winds becoming variable generally less than 10 mph outside of storms.  Winds WSW-W at 5-15 mph, with higher gusts, along mountain ridges above 2500-3000 feet.  Mild with temperatures in the 50s to lower 60s.

Wednesday Afternoon

Warm & humid.  A chance of showers & thunderstorms.  Downpours possible.  Winds SSW-SW at 5-15 mph, with higher gusts.  Temperatures varying from the 60s at the highest elevations to the mid-upper 70s.

Wednesday Night Into Thursday Morning

Partly to mostly cloudy.  Humid with areas of dense fog possible.  Scattered showers & thunderstorms.  Some Storms May Be Strong.  Downpours likely.  Winds SSW to W at 5-10 mph along middle-upper elevation mountain ridges and plateaus.  Temperatures widespread in the 50s.

A marginal risk for severe thunderstorms has been issued by the Storm Prediction Center for the entire region on Thursday.  Stay tuned to NOAA Weather Radio for any possible watches and/or warnings that may be needed.

Weather Discussion ( April 24-28 )

Weather is never dull amid the mountains, or so it seems, with chilly conditions on Saturday giving way to coldness into Sunday morning ( April 24 ).  While the MIN reached a chilly 38 degrees in Clintwood, amid fog, there was frost in higher mountain valleys.

MIN temperatures dropped below freezing in colder valleys of the High Knob Massif to Burkes Garden corridor, with an official MIN of 31 degrees in Burkes Garden being representative of valleys at around the 3000 foot level.

Amid the trend of this spring, temperatures soared from 38 degrees up to 80 degrees in Clintwood by late Sunday before dropping back ( plunging ) to 42 degrees by Monday AM.

Back to work Monday was simply gorgeous, and warm, but with a rather notable difference in temperatures between upslope locations in the High Knob Massif, Norton-Wise and Sandy Ridge communities on breezy-gusty SW winds verses the downslope locales ( much warmer ) from Pound-Grundy.

Max temperatures on Monday afternoon varied from 60s above 3200 feet in the High Knob Massif to 73 degrees at the 2650 foot level of Nora 4 SSE to 80 degrees at the 1560 foot elevation of Clintwood 1 W.

The overnight hours of Tuesday is featuring a typical nocturnal inversion with 40s in cooler mountain valleys verses upper 50s to low 60s along mid-upper elevation mountain ridges and plateaus   ( 47 degrees in Clintwood vs 63 degrees at LNP in Wise at 4:15 AM ).

The focus now shifts to a stormy, much more active weather pattern with a major severe outbreak of thunderstorms and tornadoes across the nation’s heartland today into tonight.  A few strong-severe thunderstorms may also develop on a warm frontal boundary and move southeast into the west side of the Appalachians by late today into tonight.

Other showers & thunderstorms, of a more hit-miss nature, may develop amid the warm sector south of the warm front by late in the afternoon into this evening.  The most organized storms, with a possible MCS type cluster, will track along & south of the warm front and will bear close watching by tonight for locations from the Cumberland Mountains to the northwest & north.

Downpours could produce locally heavy rainfall amounts between Tuesday Night and Thursday Night, with several rounds of showers and thunderstorms being possible.

Stay tuned to NOAA Weather Radio for any possible watches or warnings that may be needed during the next 24-48 hours.

My Weekend Forecast ( April 23-25 )

*Frost Formation Will Be Possible Into Sunday Morning In Colder Mountain Valleys, Especially At Elevations Above 2500-3000 feet.  

Fog Formation Will Be Possible In Other Locations At Low-Middle Elevations In the Clinch, Powell, Russell Fork-Levisa Fork, Holston and Cumberland River basins.

Overnight Into Saturday Morning

Mostly cloudy and turning cooler.  Winds NW-NNE at 5-15 mph, with higher gusts.  Temperatures dropping into the lower 40s to lower 50s ( coolest at the highest elevations ).  Wind chills in the 30s along upper elevation ridges.

Saturday Afternoon

Decreasing clouds by mid to late afternoon into the early evening.  Cool.  NNW-NNE winds at 5-15 mph, with higher gusts.  Temperatures varying from upper 40s-lower 50s at highest elevations in the High Knob Massif to the lower to middle 60s ( milder south toward the Tri-Cities ).

Partly cloudy skies will continue along and south-southwest of the High Knob Massif into this evening, with mostly cloudy skies along and north-northeast of the massif.  Highest elevations will remain obscured in orographic clouds ( i.e., dense fog ).

Saturday Night Into Sunday Morning

Becoming mostly clear.  Seasonably cold.  Frost possible in high valleys with fog formation in many other locations.  Winds light and variable.  Temperatures varying from the upper 20s & 30s in colder valleys ( 28-34 in coldest valleys above 2500 feet ) to the middle-upper 40s.

Sunday Afternoon

Mostly sunny.  Warmer.  Winds becoming SSW to SW at generally less than 10 mph.  Temperatures varying from 60s at highest elevations to the mid-upper 70s.

Sunday Night Into Monday Morning

Partly to mostly clear.  Milder.  Winds SSW-SW at 5-15 mph on middle elevation ridges & plateaus below 2700 feet.  SW-WSW winds 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from mid 30s to lower 40s in colder mountain valleys to the 50s on middle to upper elevation mountain ridges-plateaus.

Monday Afternoon

Partly to mostly sunny ( high clouds ).  Warm.  SSW-SW winds 5-15 mph, with higher gusts.  Temperatures varying from mid 60s to lower 70s in upper elevations to the lower to middle 80s ( warmest at lower elevations of the Russell & Levisa Fork basins ).

Monday Night Into Tuesday Morning

Partly to mostly clear.  Winds SSW-SW 5-15 mph, with higher gusts, along middle elevation ridges-plateaus at elevations below 2700 feet.  Winds SW-WSW 10-20 mph, with higher gusts, along mountain ridges above 2700 ft.  Mild with temperatures varying from the 50s to lower 60s on exposed mountain ridges-plateaus to the 40s to lower 50s within mountain valleys.

Showers & thunderstorms will become likely by late Tuesday into Wednesday & Thursday.  Locally heavy rainfall and strong-severe thunderstorms will become possible, especially west and north of the mountains ( however, this will need to be closely followed ).  Please stay tuned for updates.

Weather Discussion ( April 22-24 )

Saturday Afternoon Update

A large difference in conditions has been observed today, with partly cloudy skies south-southwest of the High Knob Massif-Black Mountain area verses low clouds along and to the north-northeast of this high terrain.  Highest elevations have remained obscured in dense fog of orographic clouds.

Cloud bases are higher, and skies are brightening at times, with drier air upstream of the mountains moving south.

Differences between this morning and this afternoon can be seen on NASA visible imagery, with increasing dry air along and north to northwest of the mountains on northerly air flow.

Observe the same pattern, with lee-side cloud breaks, has been present all day for many places across Scott, Lee and adjoining counties resting along and downstream of the windward slopes of the High Knob Massif & Black Mountain.  This has been in contrast to a persistent low cloud deck along and north of the High Knob Massif & Tennessee Valley Divide.

Temperatures in the 40s to middle 50s have been felt all day along and north of the High Knob Massif verses 60s to near 70 degrees in the Great Valley of eastern Tennessee and in lower sections of the Powell River Basin toward Cumberland Gap.

No real changes in my previous forecast other than to stress these differences more for the remainder of this afternoon into early evening until drier air overspreads the area.

One change for tonight is to increase the potential coverage of fog to include much of the area outside of places having valley floors above 2500-3000 feet where drier air will be favorable for frost formation.

My Previous Discussion

Much needed, welcomed showers and local downpours in thunderstorms soaked the mountain landscape during the Thursday Night-Friday period of April 21-22.

Some of the heaviest rain fell over the High Knob Massif with general 1.00″ to 1.50″+ amounts.  The greatest rain gauge tally reached 1.69″ at the Upper Norton Reservoir.

A seasonably cool to chilly air mass will be felt Saturday into Saturday Night-Sunday Morning, with abundant clouds that eventually give way to clearing via the advection, or transport, of much drier low-level air back into the area.

This will set the stage for frost formation into Sunday Morning in mountain valleys with drainage from upper elevations where the 850-875 MB dewpoints will be tanking overnight Saturday into the morning hours of Sunday.  With light winds, and dry air, strong radiation cooling and development of cold air drainage flows will help fill mid-upper elevation valleys with cooling air.

A simply gorgeous, much warmer Sunday is on tap following the morning chill with large mountain valley temperature rises into the afternoon.

A more active pattern returns next week with rounds or waves of showers and thunderstorms expected.  Some of these may become strong to locally severe if a NW flow pattern develops.  Stay tuned for later updates.

Have a great weekend.

My Forecast For Today ( April 21-23 )

ALERT For Anomalously Dry Conditions Continues Until Beneficial Rain Falls – Please DO NOT BURN

Overnight Into Thursday Morning

Partly to mostly cloudy ( mid-high clouds ).  Winds SSE-SSW at 5-15 mph, with higher gusts, along mid elevation ridges and plateaus below 2700 feet.  Winds SSW-SW at 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temps varying from the 40s in cooler mountain valleys to the 50s to around 60 degrees on exposed middle to upper elevation mountain ridges & plateaus.

Thursday Afternoon

Partly to mostly cloudy.  Windy & unseasonably warm.  SSW winds 10-20 mph, with higher gusts.  Temperatures varying from 60s in upper elevations to the 70s to low 80s ( warmest at lower elevations in the Russell Fork-Levisa Fork basins ).

Thursday Night Into Friday Morning

Mostly cloudy.  Scattered showers with a chance for thunderstorms.  SSW winds 5-15 mph, with higher gusts, below 2700 feet.  Winds SW-WSW at 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temperatures widespread in the 50s, varying from around 50 degrees at highest elevations to around 60 degrees warmest locales.

Friday Afternoon

Scattered showers & thunderstorms.  Cooler.  SSW to WSW winds 5-15 mph, with higher gusts ( especially on mountain ridges ).  Temperatures varying from low-mid 50s in upper elevations to the upper 50s to middle 60s.

Friday Night Into Saturday Morning

A chance for showers & thunderstorms during the evening, then mostly cloudy ( decreasing clouds in the AM ).  Turning cooler.  Wind shifting NW-NNE at 5-15 mph.  Temperatures dropping into the middle 40s to middle-upper 50s ( coolest at the highest elevations ).

Weather Discussion ( April 17-21 )

Unseasonably warm and dry conditions continue across the mountain area, with huge day-to-night temp spreads being observed ( and felt ) in mountain valleys.

*An update to Daily MAX-MIN temperatures recorded at the official National Weather Service station in Clintwood:

Official NWS Temperatures – Clintwood

( April 16 )
Saturday AM
33 degrees

Saturday PM
75 degrees

( April 17 )
Sunday AM
33.9 degrees

Sunday PM
80 degrees

( April 18 )
Monday AM
36 degrees

Monday PM
84.5 degrees

( April 19 )
Tuesday AM
40.0 degrees

Tuesday PM
81 degrees

( April 20 )
Wednesday AM
44.0 degrees

Wednesday PM
84.5 degrees

Changes are finally beginning to show up with the first chances for needed rainfall developing by later today into Friday morning in advance of an approaching cold front.

Rainfall amounts remain questionable given a long period of pre-conditioning with subsidence ( sinking air ) over the region at both upper and locally at lower levels ( with down-sloping on easterly-southerly air flow trajectories ).

The NAM Model is most aggressive, with higher rainfall totals than both the GFS and European models between now and Saturday AM.

A zoomed in look at the high-resolution NAM shows that the model is trying to display a hit-miss pattern of downpours, with typically large variations in amounts over relatively short distances ( as is the nature of convection ).  If convection does not develop locally then rainfall amounts are likely to be much lower in all places.

*There is still time to turn around an anomalously dry Spring.  However, this is important, the next 6 weeks through May will be very important as trees-vegetation green & evapotranspiration increases input of moisture into the lower atmosphere.

After the landscape greens, if dryness continues, then input of moisture into the lower atmosphere will become reduced and a feedback for the continuation of dryness will be favored.  Positive & negative feedbacks between surfaces of the Earth and overlying atmosphere become major players in weather experienced during the convective season, on scales ranging from the synoptic to the meso ( local ). 

The main period for rainfall being approximately a 24-hour window of opportunity for possible beneficial amounts, from Thursday Evening through Friday Evening.

Following drying and another nice weekend, a more active pattern is looking possible next week with a strong baroclinic zone setting up from north to south across the eastern USA.  Stay tuned as I will be updating this in coming days.

Have a great Thursday-Friday.

My Forecast For Today ( April 19-21 )

ALERT For Continued Anomalously Dry Conditions Into Thursday – Please DO NOT BURN Anything Until Beneficial Rain Falls

Overnight Into Tuesday Morning

Mostly clear.  Large vertical temperature spread between colder valleys & mild mid-upper elevation ridges-plateaus.  Light winds, except N-NW at 5-10 mph, with some higher gusts, along mountain ridges above 2700 feet.  Temps from 30s to lower 40s colder valleys to the 50s to near 60 degrees on exposed mid-upper elevation mountain ridges-plateaus.

Tuesday Afternoon

High cloudiness.  Unseasonably warm.  NW-N winds at 5-15 mph, with higher gusts.  Temperatures varying from 60s to around 70 degrees in upper elevations to the upper 70s to middle 80s ( warmest in lower elevations ).

Tuesday Night Into Wednesday Morning

High clouds.  Large vertical temperature spread between colder valleys & mild mid-upper elevation ridges-plateaus.  Winds becoming ESE-SSE at 5-15 mph along middle to upper elevation mountain ridges-plateaus.  Temperatures varying from upper 30s to mid 40s in colder valleys to upper 50s to lower 60s on exposed mid-upper elevation ridges-plateaus.

 Wednesday Afternoon

Partly to mostly cloudy ( mid-high clouds ).  Unseasonably warm.  SSE-S winds at 5-15 mph, with higher gusts.  Temps varying from 60s in upper elevations to the mid 70s to low-mid 80s ( warmest in lower elevations of the Russell Fork and Levisa Fork basins ).

Wednesday Night Into Thursday Morning

Partly to mostly cloudy ( mid-high clouds ).  Winds SSE-SSW at 5-15 mph, with higher gusts, along mid elevation ridges and plateaus below 2700 feet.  Winds SSW-SW at 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temps varying from the 40s in cooler mountain valleys to the 50s to around 60 degrees on exposed middle to upper elevation mountain ridges-plateaus.

Weather Discussion ( April 17-19 )

Unseasonably warm ( by day ) and dry weather pattern continues to dominate the mountain region, with HUGE temperature spreads between day-night being observed amid mountain valleys.

Official NWS Temperatures – Clintwood

( April 16 )
Saturday AM
33 degrees

Saturday PM
75 degrees

( April 17 )
Sunday AM
33.9 degrees

Sunday PM
80 degrees

( April 18 )
Monday AM
36 degrees

Monday PM
84.5 degrees

Widespread to patchy frost has been observed in these colder valleys during the past 3 nights, highlighted above, to contrast with much milder conditions 500-1000+ vertical feet higher.

A 48.5 degree temperature spread between Monday AM & PM is only one example of wild night-day temperature swings observed in mountain valleys during the past week.

I thank my friend Chris Allgyer, of the MECC Mathematics Department, for identifying this moth species that I captured on a cut log during Sunday. It was in a dark location, so I had to over-expose the photograph in order for it to stand out; otherwise, the picture could have been sharper with good light ( the brightness above being due to longer time exposure ).

It is enough to make even a moth’s eyes bug out.  Folks living upon the middle-upper elevation ridges and plateaus, by contrast, have experienced lesser day to night temperature spreads with 60s-70s by day and 40s-50s by night.

The Monday temperature spread on Long Ridge of Sandy Ridge, for example, at the official recording site of Wayne and Genevie Riner, varied from the upper 50s to the upper 70s ( only around 20 degrees instead of nearly 50 degrees ).

Only a few hundred vertical feet of elevation difference has been making a large difference in temperature, with well developed cold air drainage flows into hollows-valleys during recent nights with very efficient cooling in low dewpoint ( very dry ) air.

With such dry air it is going to be tough generating any significant rainfall to help with these dry conditions and forest fires burning across the region.

The latest European Model tonight is forecasting less than 0.50″ of rain to fall through this weekend.  It is showing potential for some heavy rainfall during the 5-10 day forecast period, amid the final week of April as a frontal boundary wobbles about the region to the south of a strong baroclinic zone ( temperature gradient ).

Currently the best signs for soaking rain, with showers and downpours in thunderstorms, is looking to develop out in the extended forecast period ( the 5-10 day range ) during final days of April 2016.

Meanwhile, some rain will be possible during late week but it may again be in a “weakening” mode as it fights this very dry air mass set up over the region ( a deep vertical column driven by a subsidence regime adjacent to excessive rainfall over the lower Mississippi Valley ).

*More rain fell in just 24-hours in parts of the Houston, Tx., area than has been observed across most of this region all year.  In fact, it was nearly double what has been measured in the Tri-Cities so far this year ( 9.81″ during January 1-April 19 verses more than 17.00″ in 24-hours amid wetter parts of the Houston Metro ).

Past climatology clearly shows a strong correlation to dryness in this region when excessive wetness sets up over the Mississippi Valley and southern-central Plains ( and vice-versa as wetness over this region is often correlated with dryness and drought across the former region ).  This is no accident, and is part of a great atmospheric compensation regime of rising-sinking air.

Have a great Tuesday-Wednesday.

My Forecast For Today ( April 17-19 )

Overnight Into Sunday Morning

Clear.  A large vertical temperature spread between colder valleys and milder mid-upper elevation ridges & plateaus.  Winds ESE to SE at 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges ( calm winds in valleys ).  Temperatures varying from frosty upper 20s to mid 30s amid colder valleys to the upper 40s to middle 50s along exposed ridges and plateaus.

Sunday Afternoon

Sunny.  Beautiful blue skies.  Warm.  Rapid temperature rises in valleys.  Winds NE-ENE at generally less than 10 mph.  Temperatures varying from 60-65 degrees at highest elevations to middle-upper 70s at lower elevations ( 70-75 degrees in Norton-Wise and the Sandy Ridge communities ).

Sunday Night Into Monday Morning

Clear.  A large vertical temperature spread between colder valleys and milder mid-upper elevation ridges & plateaus.  Light winds ( NE-N at generally less than 10 mph along ridges above 2700 feet ).  Temperatures varying from 30s in colder mountain valleys, with a chance for frost, to the 50s along exposed mid-upper elevation ridges-plateaus.

Monday Afternoon

Sunny.  Unseasonably warm.  Rapid temperature rises in valleys.  Light northerly winds.  Temperatures varying from 60s in upper elevations ( above 3000 feet ) to 80-85 degrees in lower elevations ( below 2000 feet ).  Mid-upper 70s are expected in Norton-Wise and Sandy Ridge communities.

Monday Night Into Tuesday Morning

Mostly clear.  Large vertical temperature spread between colder valleys & mild mid-upper elevation ridges-plateaus.  Light winds, except N-NW at 5-10 mph, with some higher gusts, along mountain ridges above 2700 feet.  Temps from 30s to low 40s colder valleys to the 50s to near 60 degrees on exposed mid-upper elevation mountain ridges-plateaus.

Weather Discussion ( April 16-19 )

A gorgeous weather pattern for this time of year is being dominated by dry air and large day to night temperature spreads, especially amid mountain valleys.

Saturday morning temperatures dipped into the upper 20s to lower 30s in colder mountain valleys of Wise, Dickenson, and northern Scott counties, with heavy to patchy frost in many places such as Georges Fork, Meade Fork, Mill Creek, Indian Creek, Norton, Ramsey, Tacoma, etc….the official MIN reached 33 degrees in Clintwood.

Following a Saturday PM MAX of 75 degrees the following temperature drop has occurred in Clintwood tonight ( the official National Weather Service MMTS readings ):

 Clintwood NWS Temperature Readings

4:00 PM
75.0 degrees

7:00 PM
61.8 degrees

8:00 PM
55.9 degrees

9:00 PM
50.9 degrees

10:00 PM
47.1 degrees

11:00 PM
44.3 degrees

12:00 Midnight
42.4 degrees

Air is dry with low dewpoints.  This aids nocturnal temperature inversion formation, via radiational cooling and cold air drainage into valleys, which is actually rather common in the mountains ( i.e., having valleys colder than mountain ridges is rather common at night ).

A weak pressure gradient is also aiding these processes by generating decoupling of light boundary layer winds.  In valleys these light winds are replaced by drainage flows generated by cooling air draining downslope, partly in response to the natural law of gravity, with the drainage flows combining to form stronger flows and even down valley mountain winds within main river valley channels.  This forms a solenoidal circulation, much like the sea breeze does along the coast, with the flow direction of this circulation reversing after sunrise and onset of surface heating. 

University Of Virginia’s College At Wise supported research through coming years will be working to develop a better understanding of micro-climatology of mountain valleys, cold air drainages, and the biodiversity that is associated with gradients within the biologically diverse High Knob Massif and Cumberland Mountains of this area.

*Temperature gradients and true differences associated with this landscape have been, and remain, poorly resolved by computer models and official forecasts for this complex landscape.

For example, the official NWS Forecast:

LEE-WISE-SCOTT-RUSSELL-WASHINGTON-
INCLUDING THE CITIES OF…JONESVILLE…WISE…NORTON…
GATE CITY…LEBANON…ABINGDON
330 PM EDT SAT APR 16 2016

TONIGHT…CLEAR. LOWS IN THE UPPER 30S TO LOWER 40S. EAST WINDS
10 MPH OR LESS.

neglects the colder mountain valleys and the milder mid-upper elevation mountain ridges & plateaus ( temperatures at Midnight being as cold as the official forecast minimums, while exposed middle-upper elevation ridges and plateaus will never drop down to this forecast range ).

This spider has 4 eyes in front, 2 in the middle and 2 in the back of his head.  There is no way anything will “sneak” up on this simply amazing design of nature.  He was “watching” me from this Wild Geranium leaf upon which he is standing.

The High Knob Landform and Clinch-Powell river basins are a core hotspot in the continental USA for the rarity & richness of limited range species, with truly extraordinary terrestrial & subterranean biological diversity.

Like many true insects, this species has a pair of compound eyes and a pair of simple eyes ( the simple eye being just above and a little to the right of his compound eye visible from this side ).

Conditions are unseasonably dry, for what is often one of the wettest times of the year, with this being reinforced once again by another blocking pattern ( the second major block of the flow field since March 1, 2016 to impact the southern Appalachians and eastern USA ).

Rain chance will eventually return, by later in the work week.  Until then, enjoy this gorgeous weather ( just be prepared for some huge day-to-night temp differences if you live or work-play amid mountain valleys ).

Have a great Sunday.

It should be noted that Dr. William ( Bill ) Gray passed away Saturday ( April 16 ).  A legendary forecaster-researcher of hurricanes and tropical weather-climate patterns.  A true pioneer of his field.  May God Bless the Gray family.