Mountain Area Forecast ( April 6-8 )

Unseasonably Cold Conditions Will Continue Through Sunday In Wake Of A Wintry Saturday

Although a little snow stuck to roads at highest elevations, and the graveled lots, most of the 1″ to 2″ of accumulation was in the woods, on grass and above ground objects ( with rime formation on trees ).

A snowfall total of 1.2″ was officially measured in Clintwood during this late season event ( 1″ being the maximum depth ).

 

Former Alert

ALERT For Significant Snowfall Developing During The Predawn-Morning Hours Of Saturday ( April 7 )

A wave of low pressure following what is a climatologically favored track for significant snowfall will be developing by late Friday into Saturday, with rain changing to heavy, wet snow.  While the most significant accumulations are likely at mid-upper elevations, the combination of recent cold and fast falling snow is expected to present a hazard across the area, especially in locations beneath upslope flow on NW-N air flow trajectories along & north of the High Knob Massif and Tennessee Valley Divide.

Snowfall Forecast – Saturday Into Saturday Evening

General 1″ to 3″ at elevations below 3000 feet in locations along and north of the High Knob Massif-TN Valley Divide

Target Snowfall of 2″ ( +/- ) 1″ for Norton-Wise.  This implies the potential for 1-3″ of snowfall within the 2000-3000 foot zone.

Locally higher amounts possible above 3000 feet.

There is currently a low-moderate chance that snowfall could be heavy enough to cause power outages, so please check back for a update as the storm track and intensity becomes more certain.

Overnight Into Friday Morning

Partly cloudy ( high clouds ).  Windy across ridges.  SW winds 5-15 mph, with higher gusts, along mountain ridges and plateaus below 2700 feet.  SW winds 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temps varying from 20s to low 30s in sheltered valleys to the low-mid 40s on exposed middle elevation ridges-plateaus.

Friday Afternoon

Becoming cloudy with a chance of rain showers by late.  SW winds 10-20 mph with higher gusts.  Temperatures varying from low-mid 40s in upper elevations to the mid-upper 50s to around 60 degrees ( downslope locations ).

Friday Night Into Saturday Morning

Rain, heavy at times.  Turning colder.  Rain changing to a mix or snow into the predawn-morning.  SW winds shifting NNW-NNE at 10-20 mph with higher gusts.  Temperatures dropping into the 20s to lower 30s, especially in locations along and north of the High Knob Massif-Tennessee Valley Divide.  Wind chills dropping into the 10s and 20s, except colder at highest elevations.

Saturday Morning Through The Afternoon

Cold & gusty with snow showers and snow, especially in the mid-late afternoon.  Winds N-NNE at 5-15 mph with higher gusts.  Temps varying from the lower 20s to the lower 30s in locations along & north of the High Knob Massif-Tennessee Valley Divide.  Milder to the south into the Great Valley.  Low clouds with riming at the highest elevations.

Saturday Night Into Sunday Morning

Evening snow showers & flurries giving way to clearing skies and diminishing valley winds.  Unseasonably cold.  Winds NW-N at 5 to 10 mph, with higher gusts, along the middle-upper elevation mountain ridges.  Temps dropping into the low 10s to low-mid 20s ( coldest upper elevations ).  Wind chills in the single digits and 10s, except colder in gusts at highest elevations.

Sunday Afternoon

Increasing mid-high altitude clouds.  Light NW-NE winds.  Temperatures varying from 30s at upper elevations to the 40s at lower-middle elevations ( especially along-north of the High Knob Massif-Tennessee Valley Divide ).

A major pattern change into Spring is being tracked for next week, with an increasing threat for strong-severe thunderstorms by late next week-weekend ( possible squall line ahead of a negatively tilted upper-air trough ).  Stay tuned for later updates.

 

Weather Discussion ( Heavy Snow? )

Early Overnight ( Saturday ) Update

Forecast models continue to struggle with this system, with the European Model group solution being followed since it has been most consistent during the past couple days.

If the European Model solution holds, a low pressure will track south of the area and be over South Carolina by 8:00 PM Saturday, placing the Cumberland Mountains in northerly upslope flow and generating the best conditions for snowfall during the mid-late afternoon into the evening prior to clearing skies into Sunday.

 

Previous Discussion

Although forecast models have struggled to pinpoint this system, a clear southward trend has occurred during the past 24-36 hours with a mean track that now is fitting past climatology of heavy snow producing systems within the High Knob Massif area.  Will this trend hold?  Check back  for an update into Friday night.

*Winter Storm Watches to the north may need to be moved south, as the heaviest snowfall is looking more likely across the higher terrain of the southern-central Appalachians.

Bloodroot, with a distinctive leaf ready to curl around it’s lovely bloom, has been covered many times in spring by snowfall in the mountains ( it is now blooming at low-middle elevations along & north of the High Knob Massif, and has been blooming, or even past bloom, in milder locations toward the southwest & south ).

Ideal cooling conditions beneath High pressure allowed temperatures to drop into the 10s amid high valleys and along highest mountain ridges in the High Knob Massif during morning hours of April 5.  An official minimum of 24.6 degrees was recorded in Clintwood ( the air temp had dropped back to a frosty 30 degrees at 3:50 AM Friday ).

Models clearly have some work to do yet before they come into agreement, with the European Model and the mean of its cluster currently being closer to the GFS Model than to the NAM Model ( the 00z April 6 run ).

So the BEST option at this present time is to look at the storm track versus past climatology and to use that as a strong bias, the result suggesting that the NAM will be increasing its output of snow in coming runs to fit what similar tracks in the past have generated ( thus, potential exists that total snowfall may be heavier than currently suggested and this will need to be updated late today into tonight ).