041117 Forecast

Mountain Area Forecast ( April 11-13 )

Overnight Into Tuesday Morning

High clouds.  Large vertical temperature spread between milder mountain ridges and colder valleys.  S to SW winds 5-15 mph, with higher gusts, along middle-upper elevation mountain ridges ( increasing to 10-20 mph along highest mountain ridges toward morning ).  Temperatures varying from low-mid 40s in cooler mountain valleys to the middle 50s to lower 60s.

Tuesday Afternoon

Partly cloudy.  Unseasonably warm.  Chance of hit-miss showers and thunderstorms.  Winds SW 5-15 mph, with higher gusts.  Temperatures varying from 60s in upper elevations to the middle-upper 70s.

Tuesday Night Into Wednesday Morning

Hit-Miss showers & thunderstorms.  Local downpours, especially during the evening.  Winds shifting WNW-NW at 5-15 mph, with higher gusts.  Temperatures dropping into the 40s to lower 50s overnight into morning.

Wednesday Afternoon

Sunny.  Blue skies.  Pleasant.  Winds N-NE at 5-10 mph, with higher gusts.  Temperatures varying from upper 50s to low 60s at highest elevations to the upper 60s to lower 70s.

Wednesday Night Into Thursday Morning

Mostly clear.  Some high clouds.  Light valley winds.  Winds shifting E-SSE at 5-10 mph, with higher gusts, along middle to upper elevation mountain ridges.  Large vertical temp spread between colder valleys and milder ridges.  Temps varying from 20s to lower 30s in coldest valleys to the 40s along exposed mountain ridges.


Weather Discussion ( Radical )

A radical change in weather conditions have occurred during recent days, from heavy snow and drifting with bitter winds at highest elevations to the first 80+ degree warmth of 2017 amid lower elevations ( below 2000 feet ).

Looking Across Sprawling Top of High Knob Massif To Mount Rogers-Whitetop

Snow capped high mountain summits from the High Knob Massif and Russell Beartown Mountain southwest along the Appalachians to massifs of Mount Rogers-Whitetop, Roan Mountain, and the Black Mountains stood clearly out during afternoon hours of April 7.  Snowfall totals of up to 13.0″ were reported on Mount Mitchell, with 8″ near the summit level of Mount LeConte in the Great Smokies.

This was a notable late season winter storm for the top of the Appalachians ( featuring 50-60+ mph wind gusts ).

Drifting snow was also notable, with 1-2 feet at upper elevations in the High Knob Massif ( 17″ shown below by afternoon ) along the highest mountain crest lines ( and high gaps ).
Snow Drifts Along High Mountain Ridges In High Knob Massif – PM of April 7

Spring continues to progress, despite this wintry blast, especially within lower-middle elevations which missed accumulating snowfall ( at elevations below 3000 feet ).

Wild Geraniums ( Geranium spp. ) Beginning To Bloom

A chance for hit-miss showers and thunderstorms, with large variations in rainfall amounts, will be possible by Tuesday afternoon into Tuesday Night.

NAM 3 KM Model Total Rainfall Forecast To 8:00 AM Wednesday ( April 12 )
The exact placement of heavier rain amounts, as noted above, can not be known with the model only generating a best guess.  As is typical during the warm season, large variations in rain amounts over short distances are common when convection begins to rule the precipitation pattern.
European 51-Member MEAN 500 MB Height Anomalies Forecast: Days 6-10

 Although temperatures will be chilly in mountain valleys during Wednesday Night into Thursday Morning, especially high valleys within low dewpoint air and drainage flows, the general pattern is unseasonably warm in the MEAN during the next 1-2 weeks.

While jet stream disturbances will have greatest impacts upon western and northern portions of the USA, trailing fronts will gather enough moisture and instability for periodic chances of showers and thunderstorms.  If any front stalls, as some models suggest by late week into next week, this could help to prolong precipitation chances.  Daily details yet to be determined.
European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 6-10