022717 Forecast

Mountain Area Forecast ( Feb 27-Mar 1 )

ALERT For Strong SSW-WSW Winds From Tuesday Afternoon Through Wednesday Afternoon


The Storm Prediction Center Has Issued An Enhanced Risk For Severe Thunderstorms Wednesday ( Today ) With A Wind Damage Producing Squall Line Expected To Arrive At The VA-KY Border Around Mid-Day

SPC Updated Wind Damage Risk
SPC Updated Discussion
SPC Risk Of Wind Damage Within 25 Miles Of Any Given Point

*An Outbreak Of Severe Thunderstorms ( Squall Line With Possible Local Supercells In Advance Of Line ) Is Expected During Early-Mid Afternoon Hours On Wednesday. 

**Wind Damage will be the greatest threat, with a notable power outage potential.  Damaging hail and local tornado spin-ups can not be ruled out.  This is a SERIOUS Setting.

HRRR Model Future Doppler Forecast Of Squall Line Position At NOON
HRRR Model Future Doppler Forecast At 11:00 AM Wednesday – March 1, 2017

Watches & Warnings Will Be Likely – Stay Tuned To NOAA Weather Radio & Local Media For Updates

Overnight Into Monday Morning

Increasing high clouds.  SSE-S winds 5-15 mph, with higher gusts, on mountain ridges below 2700 feet.  SSW-SW winds 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from 20-25 degrees in the colder valleys to readings steady or rising into upper 30s to lower 40s along gusty mountain ridges.

Monday Afternoon

Mostly cloudy ( mid-high clouds ).  SSE-SSW winds 10-20 mph, with higher gusts.  Temperatures varying from 40s at highest elevations to the middle 50s-lower 60s.

Monday Night Into Tuesday Morning

Partly to mostly cloudy.  SSE-SSW winds 10-20 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures in the upper 30s to the upper 40s.

Although atmospheric conditions able to support strong-severe thunderstorms will develop Tuesday Afternoon, some parameters ( i.e., instability-moisture and lift ) will remain strongest and best defined west of the Appalachians.
Increasingly strong wind fields will develop intense shear ( storm relative helicity ) along the mountains Tuesday afternoon-night, such that a strong or severe thunderstorm can not be ruled out with activity that may move in from the west or form locally. 

Tuesday Afternoon

Partly-mostly cloudy.  Unseasonably warm.  A chance for showers & thunderstorms ( a locally strong-severe storm possible ).  Becoming windy.  SSW winds 10-20 mph, with higher gusts, below 2700 feet.  SSW-SW winds 15-25 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from middle-upper 50s at highest elevations to the upper 60s to mid 70s ( warmest downslope sites from Pound-Clintwood to Haysi-Grundy ).

Tuesday Night Into Wednesday Morning

Mostly cloudy.  Windy & unseasonably mild.  A chance for showers & thunderstorms ( a locally strong-severe storm possible ).  SSW to SW winds 15-25 mph, with higher gusts, below 2700 feet.  SW winds 20-30 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures widespread in the 50s to around 60 degrees.

A spring severe weather day is on tap for Wednesday with  potential for an Outbreak of Strong-Severe Thunderstorms across the Tennessee Valley and southern Appalachians.

Wednesday Afternoon

Windy with showers & thunderstorms developing.  Storms could be strong to severe with damaging winds.  Downpours likely.  Hail possible.  Winds SW at 15-30 mph, with higher gusts.  Temperatures varying from 50s at highest elevations to the mid-upper 60s.

Much colder air is again expected Thursday-Friday ( March 2-3 ) with widespread below freezing temperatures and wind chills.


Weather Discussion ( In Like A Lion )

Monday Afternoon Update

While Wednesday ( March 1 ) is clearly going to be THE DAY when all ingredients converge toward an outbreak of severe thunderstorms along the mountains, a strong-severe storm can also not be ruled out beginning Tuesday afternoon for locations along and west of the Cumberland Mountains and Cumberland Plateau ( SE Kentucky and Tennessee ).

High Knob Massif Webcam – University Of Virginia’s College At Wise
Winds Monday have been a little stronger and temps a bit cooler than my initial forecast, amid an ominous looking haze in late February at the conclusion of Meteorological Winter.
NAM Model Forecast Sounding Over Norton At 1:00 PM Wednesday – March 1, 2017

Perhaps that ominous look from the CAM extends from the many graphics I have been viewing showing conditions that become favorable for tornadoes on Wednesday, with an inverted-V sounding and twisting storm slinky’s forecast vertically above Wise County and the City of Norton.

*The above just being chosen points, as these conditions will extend across a large region.
NAM Model Forecast Sounding Above Norton At 4:00 PM Wednesday – March 1, 2017

If these trends continue, then a RARE Enhanced Risk of Severe Thunderstorms ( rare for the end of Meteorological Winter and Dawn of Meteorological Spring ) may be issued over or very close to the mountain area by the SPC during Wednesday ( with a Tornado Watch ).  Stay tuned for updates on this developing severe weather threat.

Reference Major Severe Outbreak Of March 2012 to review a setting that occurred 5 years ago at the beginning of March.


Previous Discussion

An increasing pressure gradient will crank up strong winds to usher in the month of March, which is literally looking to ROAR into the mountain region.

GFS Model Mean Sea Level Pressure & 850 MB Wind Field Forecast – 7 AM March 1

A strong wind field will generate ROARING SW winds into the mountains starting later Tuesday into Wednesday.

Parameters for severe thunderstorms will then need to be closely monitored into the afternoon hours:

SLIM: Shear-Lift-Instability-Moisture

NAM 12 KM Model MSLP and CAPE Forecast At 4:00 PM Wednesday – March 1, 2017
Storm relative helicity values are currently forecast to be notable ahead of a strong cold front, along with some CAPE ( Convective Available Potential Energy ) and increasing moisture.
Storm Prediction Center Risk Regions 7 AM Tuesday to 7 AM Wednesday

While the Storm Prediction Center already has the region outlooked for potential severe thunderstorms, this will be better defined and adjusted during the next couple of days.

Storm Prediction Center Risk Region For Wednesday ( March 1 )

The Bottom Line…

March 2017 will literally ROAR into the mountains on strong SW winds.  Increasing moisture-instability will combine with shear to set the stage for strong-severe thunderstorm development ( highest threats west of the mountains Tuesday and along the mountains and Tennessee Valley during Wednesday ).

Stay tuned to NOAA Weather Radio and your favorite media sources for updates, possible watches and/or warnings which may be needed Tuesday-Wednesday.