Flooding-High Water Levels
Many creeks and mainstem rivers are near or above flood stage on this Sunday morning, with extensive local flooding in impacted locations.
Big Stony Creek was nearly 2 feet above flood stage in northern Scott County, as of 5:30 AM, with flooding on the Wise County side of the High Knob Massif along and on tributaries of South Fork of Powell River and the Guest River. Extreme caution is advised.
Torrents of water gushing out of the High Knob Massif have quickly skewed the Clinch River well above its forecast trajectory (above), as of 6:15 AM Sunday, with strong current rises.
The Guest River at Coeburn has established a new record daily flow, and was still rising as of 5:45 AM.
Please do not drive into flooded locations and allow water time to recede.
The Bottom Line_Minor to locally moderate flooding is impacting some locations, while all other streams are elevated. Expect levels on headwater creeks to begin dropping into mid-day, while mainstem river levels will continue to rise. Stay tuned to NOAA weather radio and local authorities for updates.
Saturday Evening Concerns
A early Saturday evening update is to highlight the main concerns upcoming through the next 24-hours.
*Downpours Into The Overnight – The atmosphere is becoming unstable in advance of a upper air trough axis and its associated cold front. While strong-to-severe thunderstorms west of the Appalachians will be weakening, they will be producing downpours.
The HRRR Model seems to have a descent handle on the evolution of current storms, with a general 0.50 -1.00″ of additional rain expected ( locally higher amounts will be possible ). These amounts are also supported by new runs of the European Model and NAM Model.
This could trigger flash flooding and otherwise act to enhance ongoing high water levels and issues. More mud-rock slides will also be possible. This is a high concern given this activity will be occurring at night when it is more difficult to monitor conditions.
Given so many creeks currently around flood stage this should be considered a life-threatening situation and any possible precautions should be taken now.
*ROARING Winds Sunday – While a gush of strong wind will mark the passage of a cold front prior to sunrise, a particular concern is after sunrise Sunday when return of sunshine will help aid the downward transfer of high momentum air aloft to the ground.
A unidirectional SW-W flow will support this high wind setting. Given flooded and saturated soils this increases the chance for wind damage. Extra caution will need to be taken around trees through Sunday as any ongoing flood clean-up continues, in addition to those who homes are surrounded by trees.
Enhanced Flood Risk Into Sunday
An enhanced risk of flooding is being extended into Sunday with more significant rounds of moderate to heavy rainfall expected Friday into this weekend.
I consider this to be one of the most threatening flood settings in years, and if we can get to Sunday without major problems due to flooding then we all will be blessed and very thankful.
If the European Model forecast of 3.00″ to 4.00″ of additional rainfall is realized, a flood emergency will need to be declared in some locations during the next rounds of rainfall (Friday-Saturday) given continued high water levels and super-saturated conditions.
Friday Evening ( February 22 ) Update
Steady rains during the past 24-hours have kept the mountain area water logged and primed for trouble with heavier rainfall totals to come.
The only change in this update is to push the heavier rain threat throughout Saturday, and I think all NWS Forecast Offices serving this area will need to push the end time for the Flood Watches into Sunday AM.
I have to say that I am more concerned tonight than last night, given a model trend toward concentration of heaviest rains into a time-frame that will feature more of a convective nature + a potential that rains will also be areally concentrated within a band.
The main difference tonight between the NAM and European Model group is that the high-resolution NAM 3 KM also includes eastern Tennessee, while the European and NAM 12 KM is more focused upon far southwest Virginia and southeast Kentucky.
The other main difference, of course, for those who are closely following these models, is that the NAM group wants to also concentrate the areal coverage of heaviest rainfall across the Mountain Empire versus the European group which is more areally spread.
From a meteorology perspective, positive feedback tends to be more often associated with the warmer months of the year; however, given this anomalous wetness in place it is a real factor to consider now.
This means that support for heavy rain will be even higher as the upper dynamics arrive to lift air ahead of a potent upper-wave and storm system.
The Bottom Line…A dangerous flood and mud-rock slide threat continues through Sunday AM with the most recent model runs tending to concentrate the heaviest new rainfall totals into the period between Midnight Saturday and the predawn of Sunday.
Although I have hesitated to post this, not wanting to take any focus away from this flood setting, a strong wind setup will develop Sunday as an intense surface low lifts across the Great Lakes.
A 978 MB low will cause strong winds, with a nearly unidirectional flow in a dry slot enhancing the down-ward transport of high momentum air. While skies will turn sunny, the high wind gusts will combine with flooded and/or saturated ground to increase the risk for uprooted trees and power outages.
The Currently Expected Scenario
Rain showers and rain will once again overspread the mountain landscape Thursday night into Friday AM.
It does not require a meteorologist to see the concern upcoming, with a deep tropical connection (what is called an atmospheric river) tapping moisture which extends thousands of miles into the Pacific Ocean in advance of a powerful upper wave (number 3 and the final one, thankfully, in this current wave series).
If the European group scenario is correct, and it has been the best model forecasting the synoptic-scale setting, the main period of concern will begin during Friday afternoon and continue into mid-morning to early afternoon of Saturday. A break follows ahead of strong-severe thunderstorms developing along a cold front to the west of the Appalachians, which impacts the local mountains into early Sunday with downpours (low chance of damaging winds).
The latest run of the NAM 12 KM Model is coming into agreement with the European group, as has been the trend observed this week.
Given current stream levels and ground moisture this scenario would cause significant flooding. This being prior to any additional downpours that might occur into early hours of Sunday (below).
Mud-rock slides and power outages may complicate this already dangerous situation.
The main local concern will not be severe storms but downpours, which could add to any ongoing flooding or trigger new flooding.
The European Model predicts around 0.50″ of basin-average rain during the passage of a squall-line and front, suggesting locally higher and lower amounts and that much of this will fall with downpours into early hours of Sunday (before sunrise).
The NAM Model has unfortunately come in with a forecast that is very close to the European Model group, featuring a final round of heavy downpours into early hours of Sunday along a weakening line of thunderstorms (which may spawn tornadoes west of the Appalachians on Saturday).
Headwater creeks draining the High Knob Massif are continuing to run (roar) at high levels on Thursday.
This includes the South Fork of Powell draining the Big Cherry Lake basin into the East Stone Gap area of Wise County, as well as Big Stony Creek draining into the Fort Blackmore area of Scott County ( plus many more steep creeks draining the upper elevations ).
The Clinch River peaked at 18.04 feet during this recent event at Speer’s Ferry. While the river is forecast to reach 19.5 feet near 8 PM Saturday, I believe it will be significantly higher.
Clinch River At Speer’s Ferry At 7:15 PM Thursday_February 21, 2019
This is based on rainfall amounts forecast by the European group versus the observed differences between what has recently been predicted by the European group and actual rain amounts.
The Powell River peaked at 15.98 feet during this recent event near Jonesville, Va., in Lee County.
Powell River near Jonesville At 7:45 PM on Thursday_February 21, 2019
Originally published during February 13, 2019 ( following sections ) and updated on February 21.
Serious Flash Flood & Flood Pattern
A serious flood threat is upcoming for the Mountain Empire as a series of upper air waves moving across the nation periodically lift unseasonably moist air.
All EMS Departments need to prepare now for the real potential of flood emergencies and evacuations, if any preparations and planning need be done.
I seldom make statements like this in advance of an event, but the amazing consistency of this pattern across forecast models in combination with observed past climatology of flood events, and antecedent wet conditions during this past year, demands that extra effort be put into stressing this in advance.
Mean Upper Air Flow During The April 1977, March 2002, February 2018 Floods
It takes very little research to understand the threat presented by the upcoming pattern. I have plotted 3 upper air flow patterns for past floods, ranging from the benchmark river flood event of April 1977 to the significant March 2002 flood to a much less serious but still important flood in February 2018.
These past events all possessed a notable orographic component, with the most severe flooding west of the Blue Ridge across the western Appalachians.
European 51-Member Ensemble Mean 500 MB Height Anomalies Forecast_Days 1-5
It is simply amazing, scary, and no mistake that past upper air flow regimes match this upcoming pattern predicted by the European Ensemble Mean.
Although every weather system is different, there is great value and strength in past climatology when it is used in a proper way to aid recognition of patterns which have inflicted pain and suffering.
European 51-Member Ensemble Mean 500 MB Height Anomalies Forecast_Days 4-8
There is no real change in this pattern until after the February 26 time period, with latest ensemble trends suggesting a shift to colder conditions by the end of February into early March.
European 51-Member Ensemble Mean 500 MB Height Anomalies Forecast_Day 10
An eastward shift in upper air troughing by the end of February into early March is predicted to occur, with a colder weather pattern.
Water Logged Mountain Landscape
The mountain landscape is water logged. That is not breaking news. Streams are running high following recent rains and antecedent wetness extending back through the past year of 2018.
Big Stony Creek of High Knob Massif_February 2019 Stream Levels
A general 2.00″ to 3.00″ of total precipitation during the February 10-12 period pushed mountain creeks to around flood stage within the High Knob Massif area.
Creeks crested around a foot below flood stage during the recent precipitation event, during February 15-17, when a general 1.50″ to 2.00″ were observed.
While NWS maps show the general areas which have had the most rainfall, they struggle to resolve local conditions such as the general 8.00″ to 10.00″+ totals which have occurred within the City of Norton and High Knob Massif-Black Mountain corridor.
This is partly due to local terrain blocking that causes the Doppler radar out of Morristown, Tn., to display a void zone along a radial that expands outward with distance across the High Knob Massif. This is evident during live precipitation events when looking at this Doppler (it is not a factor on JKL Doppler but since the image above is from a composite of Doppler’s it is still reflected in this final estimation product).
A real-time example from this recent storm event reveals the radial void which is factored into the composite analysis to cause under-estimations.
February 1-21, 2019
City of Norton Water Plant
Daily Hand-Measured Precip
( 9:00 AM / 24-Hour Daily)
02/05 0.03″
02/06 0.06″
02/07 2.14″
02/08 0.63″
02/11 0.58″
02/12 0.37″
02/13 1.01″
02/16 0.38″
02/17 0.14″
02/18 0.95″
02/20 1.09″
02/21 1.19″
February Total: 8.57″
January Total: 5.44″
2019 Total: 14.01″
December 1-February 20: 21.95″
Precipitation totals have already reached 16.00″ or more at upper elevations in the High Knob Massif and Black Mountain during 2019, with 24.00″+ during the December-February period of this winter (*).
*Remember this does NOT include addition of moisture by addition of fog drip and rime deposition on trees at upper elevations, nor does it include often significant rain gauge under-catches caused by strong winds, such that effective total moisture input has been much greater in orographic locations (especially at elevations above 3000 feet).
February 2018_Virginia Record
One year ago the area established new marks for February wetness in Virginia, with locally more than 14.00″ of total precipitation. There has been little respite since then with respect to general wetness.
Black Mountain Mesonet
January Total: 6.49″
2019 Total: 16.05″
December 1-February 12: 24.44″
Climate Prediction Center soil moisture maps do not fully capture the picture, given under-estimating of amounts which have fallen in the orographic zones including communities such as Appalachia, Big Stone Gap and the City of Norton, as well as Duffield, Fort Blackmore and Dungannon ( to note a few ).
Palmer Hydrological Conditions
While the southwestern mountain climate zone in Virginia is only rated as very moist, there is no doubt that counties along the VA-KY border are actually in the extremely moist category.
Eastern portions of southwestern Virginia, which have more official weather stations, have been much drier than far southwestern Virginia to skew the climate zone drier than local reality.
A perfect example being Blacksburg, where the February precipitation total has been 3.53″ and the 2019 year-to-date tally has been 6.29″ ( less than the City of Norton has measured just during February ).
Norton has measured 11.21″ more precipitation than Blacksburg since December 1 ( only 48.9% as much precipitation has fallen in Blacksburg this winter ).
Differences are even greater between Norton and Bluefield, Wv., with 11.81″ less in Bluefield since the beginning of meteorological winter.
Generalized Average Run-off Anomalies_February 2019
The big concern moving forward is a pattern that will be favorable for excessive precipitation, as generally agreed upon by all major model groups.
GFS 21-Member Ensemble Mean Total Precipitation Forecast_Next 2 Weeks
The 51-Member European group is similar and has been more consistent than the GFS in predicting excessive precipitation amounts next week.
250 MB Jet Stream_Northern Hemisphere
Due to such a powerful jet stream flow coming off Asia into the Pacific Ocean the concern is very real from an energetics perspective, but placement of heaviest precipitation axes will be dictated by each individual wave. It is simply not yet possible to tell where flooding will occur very far in advance.
European 51-Member Ensemble Mean 500 MB Height Anomalies_Days 6-10
Another disturbance impacting the Polar Vortex may attempt to turn conditions colder down the road, but that is not yet showing up in modeling with the mean of the 51-members of the European group continuing to show a pattern very conducive for heavy-excessive precipitation through the 6-10 day range. Atlantic, Gulf and Pacific moisture feeds are being predicted.
The Bottom Line…a serious Flash Flood and Flood potential exists through the next week to 10 days and is being enhanced by both very wet current and past conditions plus a highly energetic jet stream flowing into the USA from upstream to interact with multiple moisture sources. Stay tuned for updates.
Updated: A total of 1.1″ of snow were officially measured in Clintwood into morning hours of Saturday, February 16, with icing to the south.
Former Alerts Issued February 15
ALERT For Icing – Snow To North
Icing which is ongoing at high elevations within the High Knob Massif-Black Mountain will be dropping with the freezing level into the overnight-predawn hours to elevations of Norton-Wise.
Black Mountain Mesonet
A general 1″ to 3″ of snow is currently expected from Pound-Clintwood northward to Pikeville, Ky., during a fast predawn-morning period of snowfall.
Mixed precipitation, with mainly less than 1″ of snow is expected to the south where sleet and icing will be more common. Significant icing will be possible at upper elevations in the High Knob Massif.
Caution for walking and traveling on above ground objects is advised overnight into Saturday morning.
A change to snow, which could limit icing, will be dependent upon the vertical temperature profile.
While the European Model group has consistently been forecasting a change to snow, with 2-3″ in the Wise area, higher resolution models maintain a layer of above freezing air near and above 850 MB to keep precipitation in the form of freezing rain and sleet, with the best chance of snow to the north.
Previous Outlook
Locations along and north of the High Knob Massif and Clinch Mountain in southwestern Virginia will need to monitor the potential for icing and snow developing during the predawn-morning hours of Saturday.
NAM 3 KM Model_Freezing Rain Forecast
Latest model trends are supportive of icing, especially at elevations above 2300 feet, with potentially significant icing and freezing fog development at upper elevations in the High Knob Massif from the predawn hours of Saturday into early evening ( prior to rising temperatures ).
NAM 3 KM Model_Forecast Vertical Sounding
Updated: February 19
ALERT For Snow To Sleet Then Rain
Tuesday Evening Update – Precipitation began as snow and changed to sleet-freezing rain on High Knob and began as sleet in Clintwood, followed by mixing of rain and sleet (11:00 PM).
Freezing Rain on Eagle Knob of High Knob Massif
Around 0.40″ of rain has fallen, most in freezing form at the highest elevations. A similar setting generated major icing which caused severe damage in November 2018. With luck, warmer air will win this upslope cooling battle soon to help prevent more damage (but that is not yet known, so caution for possible downed trees and limbs is advised for travelers within the upper elevations).
Enough sticking has occurred to cause slippery conditions with the moderate-heavy initial fall of sleet, but melting will occur through the evening outside of upper elevations (where temperatures remain below freezing at high elevations).
Mesoscale Discussion
Warm air advection (transport) will begin during Tuesday evening around the 700 MB level and deepen over time in the vertical. Any snow developing with evaporative cooling will change to sleet, then mainly to rain as the warm air deepens vertically.
Local exceptions could be a period of freezing rain within upslope zones of the High Knob Massif where orographically forced adiabatic cooling may offset warm air advection at the surface for a period of time prior to being overwhelmed by warming air.
A gusty E-SE flow will prevent frozen accumulation within the downslope corridor lee of the High Knob Massif, from Powell Valley toward Big Stone Gap into adjacent locations.
The same type of precipitation transition is expected along the Blue Ridge, at high elevations, in western North Carolina to the peaks of Mount Rogers and Whitetop Mountain in southwestern Virginia.
Mountain peaks will go from snow to sleet to rain, versus locations at lower elevations within a wedge of cold air banking up against the eastern slopes.
A transition into widespread freezing rain-sleet will occur beneath mountain peaks, where warm air aloft will flow over a cold air damming wedge (i.e., worst conditions will be developing beneath high mountain crest-lines which stand above the CAD wedge) into the predawn-morning hours of Wednesday across western North Carolina into the Blue Ridge-western Piedmont provinces of Virginia.
ALERT For High Winds Wednesday_Especially From The Overnight Through The Day In Mountain Wave Zones And At Mid-Upper Elevations_Possible Power Outages Due To Downed Trees & Limbs
Black Mountain Mesonet At 5:25 AM_February 20, 2019
