050517 Forecast

Mountain Area Forecast ( May 5-7 )

An Alert For Frost & Freezing Conditions May Be Needed Across Much Of The Area By Monday Morning

*Temperatures around or below freezing will be possible on highest peaks into Saturday morning, and in high valleys and peaks on Sunday morning.

Overnight Into Friday Morning

Showers with a chance of thunder.  Winds shifting SW to WNW at 5 to 15 mph, with higher gusts.  Temperatures dropping into low-mid 40s at highest elevations to the upper 40s to mid 50s.  Low clouds ( dense fog ) in upper elevations.

Friday Afternoon

Showers.  Low clouds & chilly.  Winds SSW-W at 5-15 mph, with higher gusts.  Temperatures rising very little or slowly falling in the 40s ( upper elevations ) and middle 50s to lower 60s at middle-lower elevations by late afternoon.

Friday Night Into Saturday Morning

Rain & showers.  Turning colder.  Rain becoming mixed with or turning to snow at elevations above 3500 feet overnight into morning.  WNW to NW winds 10-20 mph, with higher gusts.  Temperatures varying from around freezing at highest elevations to low-mid 40s.  Wind chill factors within the 20s and 30s, except 10s in gusts on highest summits ( above 3600 feet ).  Orographic clouds-dense fog upper elevations ( becoming freezing fog highest peaks ).

Saturday Mid-Morning To Mid-Day

A break possible in showers.  Partly to mostly cloudy.  Winds WNW-NW 5-15 mph, with higher gusts.  Temps in the 30s ( upper elevations ) to the 40s ( low-middle elevations ).

Saturday Afternoon

Low clouds.  Showers redeveloping.  Rain and/or snow mix on highest peaks.  Local small hail possible.  Winds WNW-NW at 10-20 mph, with higher gusts.  Temps varying from 30s in  upper elevations to middle 40s to lower 50s. Dense fog at upper elevations.  Wind chills varying from 20s in upper elevations to the 30s to around 40 degrees.

Saturday Night Into Sunday Morning

Low clouds.  Showers tapering to drizzle before ending.  Clearing possible by morning.  Cold.  Winds W-NW at 5-15 mph, with some higher gusts.  Temperatures varying from 20s to around 30 degrees on highest peaks and high valleys to the upper 30s to around 40 degrees.  Wind chills varying from 10s & 20s at highest elevations to the 30s.  Dense fog in upper elevations ( freezing fog highest peaks ) giving way to clearing toward morning.

Sunday Afternoon

Mostly sunny (  deep blue ) skies.  Gusty & chilly.  Winds WNW-NW at 10-20 mph, with higher gusts.  Temperatures varying from low-mid 40s at highest elevations to the middle-upper 50s.  Wind chills in the 30s and 40s across middle-upper elevation mountain ridges.

 

Weather Discussion ( Chilly & Wet )

An unseasonably cold, for this time of year, pattern is taking shape for this weekend into much of next week.

High Knob Massif Webcam – University Of Virginia’s College At Wise
Dramatic cloud formations, as often is the case when SE winds blow across the High Knob Massif, were on display throughout much of Thursday ( May 4 ).
A persistent standing wave on the SE flow stood for hour after hour as strong-gusty winds blew upward across the high country.  Although changing specific appearance at any given moment, the general cloud formation remained consistent through time.
High Knob Massif Webcam – University Of Virginia’s College At Wise

While below freezing air and even flakes of snow are not uncommon during May, especially in the high country, the upcoming pattern is going to be unseasonably cool during the next 10 days ( in the mean ).

Majestic Spring Afternoon In Big Cherry Wetland Valley – May 3, 2017
Temperatures in the 30s have occurred in high valleys within the High Knob Massif recently during morning hours of April 26 and May 3; however, temperatures in the 20s within high valleys will likely occur by early next week ( perhaps as early as Sunday AM if skies should clear before sunrise ).  This is a given.
The more critical forecast will be for lower-middle elevations, even the thermal zone orchard belt, where some frost sensitive crops may already be planted.  Stay tuned for updates.
European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 1-5

The European Model group ensemble MEAN is showing  troughing across the eastern USA, with a general Omega Blocking feature that allows the pattern to reload next week just as it appears that warming might take hold.

European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 6-10

This results in an unseasonably chilly May pattern.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 1-5

If this forecast verifies, unseasonably cold air for this time of year will continue through the first half of May.  Timing when frost and freezing conditions occurs will be the main forecast challenge upcoming.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 6-10