Mountain Area Forecast ( March 11-14 )

ALERT For A Prolonged Period Of Wintry Conditions From Monday-Wednesday ( March 12-14 ).  The Worst Conditions Will Develop During Three Periods: 

Predawn to Mid-Morning of Monday ( March 12 )
*General 1″ to 4″ along-north of High Knob Massif

Updated: Monday At 4 PM
Monday Night-Tuesday Morning
NW Upslope Flow Snow Showers
( 1″ to 2″ with locally higher amounts )

Snow showers will redevelop in NW upslope flow during Monday Night into Tuesday Morning.  A general 1″ to 2″ of snow is expected along and west of the Cumberland Front, with locally higher amounts in the High Knob Massif. 

***NOTE: Whiteouts Are Coming***

Updated: Evening March 13
Late Tuesday PM-Wednesday AM
NW Upslope Flow Snow Squalls
( 3″ to 5″ with locally higher amounts )

Snow showers, intense snow squalls and possible snow-streaks are expected to develop in NW upslope flow during late Tuesday into Wednesday Morning.  Whiteout bursts of intense snow are expected to greatly reduce visibility and to generate widespread hazardous travel conditions, amid bitter air, along the upslope side of the mountains.

The main snow band is initially forecast by models to develop north of the Cumberland Mountains from the central portions of Kentucky into southern West Virginia, followed by a prolonged period of NW Upslope Flow with a Great Lake moisture connection as a strong mid-latitude cyclone intensifies over the western Atlantic Ocean.

Sunday Night Into Monday Morning

Rain developing.  Rain mixing with and changing to snow from top to bottom during the overnight-morning hours of Monday.  E-SE winds backing NE-N at 5-15 mph with higher gusts.  Turning colder with temperatures dropping into the low to mid 20s ( highest elevations ) to the low 30s ( Powell Valley and other low elevation sites ).  Wind chills falling into the 10s and 20s along mid-upper elevation mountain ridges.  Rime formation at highest elevations.

Monday Afternoon

Mostly cloudy.  Cold & windy.  A chance of snow showers & flurries.  NW winds 10-20 mph, with higher gusts.  Temps varying from 20s in upper elevations to the 30s at middle and lower elevations.  Wind chills in the 10s & 20s ( coldest in upper elevations ).

Monday Night Into Tuesday Morning

Snow showers & flurries redeveloping.  Localized snow squalls ( bursts of heavy snow ). Cold.  NW winds at 10-20 mph, with higher gusts.  Temperatures varying from middle 10s at the highest elevations to the mid-upper 20s.  Wind chills in the single digits & 10s, except dropping below zero in stronger gusts at highest elevations.

A setting favorable for intense snow squalls, with whiteout conditions, is currently shown by models to develop by late Tuesday into Tuesday Night.  This could be the worst period of this event given a combination of unseasonably cold air and bitter wind chills.

Tuesday Afternoon

Snow showers & flurries, with snow squalls becoming likely along with possible snowstreaks ( training squalls ).  WNW-NW winds 10 to 20 mph, with higher gusts.  Temperatures varying from 20s in upper elevations to the 30s at middle to lower elevations.  Wind chills in the 10s and 20s ( coldest in upper elevations ).

Tuesday Night Into Wednesday Morning

Snow showers & squalls ( possible snowstreaks ).  Cold.  Winds WNW-NW at 10-20 mph with higher gusts.  Temps dropping into 10s to around 20 degrees, except single digits to around 10 degrees at highest elevations.  Wind chills in the single digits and 10s, except below zero at highest elevations.  Rime formation at high elevations.

25th Anniversary Of The March 1993 Superstorm

Reference the above link for a review of one of the greatest winter storms ever documented in this region ( scroll down to the section about the then 20th Anniversary of this Monster Storm ).

 

Weather Discussion ( Models Struggle )

Tuesday Afternoon Update

While only light snow showers & flurries have occurred so far during Tuesday, DO NOT THINK that is going to remain the case.

While worst conditions will develop between midnight and sunrise Wednesday, impact snow squalls will start to develop during the sunset-midnight period ( if not locally before ).  I expect intense squalls with a very potent upper air setting that will combine with low-level orographics.  Be Prepared!

 

Monday Evening Update

I updated to introduce snow squalls earlier than in my initial forecast, with 0.5″ of new snow accumulating within only around 10 minutes in Clintwood prior to midnight.  I have also added the possibility of snowstreak formation during Tuesday afternoon and Tuesday Night with a very unstable atmosphere developing on forecast soundings.

*Local thundersnow or CSI slantwise convection will be possible.

Monday Afternoon Update

A cold, damp atmosphere is lingering in wake of the first round of snowfall with cloud bases trying to lift and break as of late afternoon ( a battle between NW usplope flow and a temporary surge of drier air ).

UVA-Wise graduate Layton Gardner just measured 2″ of mean snow depth on the ground at his home in Wise.

A total of 1.4″ of snow fell in Clintwood ( 1″ on the ground ) versus a general 2-4″ of ground depth from northern slopes at the City of Norton Water Plant ( 2″ ) to upper elevations in the High Knob Massif ( High Chaparral to Eagle Knob ).

The focus now turns to unseasonably cold air and the re-development of flurries, snow showers, and eventually squalls in a Great Lake connected NW upslope flow.

While low density snow will drop a new 1″ or 2″ on the upslope side of the Cumberland Front by Tuesday AM, the worst period upcoming will likely develop by late Tuesday into Wednesday when a setting favorable for intense snow squalls and possible snowstreaks ( which are training squalls ) will develop.

Both Lake Superior & Lake Michigan, from which streamline flow will originate, are wide open for business, so it will be GAME ON as this interacts with the high terrain along and just west of the Cumberland-Allegheny Front.

 

Previous Discussion

Forecast models continue to struggle with a system that has been seen to be problematic now for days.  The development of a heavy, but narrow band of snow is again being shown, surrounded by lighter snowfall, with exact placement of  this band and timing of a change from rain to snow being the core problems ( giving forecaster’s heartburn and a decreasing amount of follicular hair!!! ).

Differences in models are displayed in their snowfall forecasts for the next 24-hours, with little to none being shown by the operational GFS ( above ) to heavy snow on  the high resolution NAM ( below ) for upslope locations within far southwestern Virginia.

The European Model and its 51-Member Ensemble MEAN, which I am not allowed to show, is currently a compromise between these solutions with a forecast of 3″ in Wise and a general 1-3″ across the area during the next 24-hours.

But the European struggles to resolve local terrain features, such that if a easterly flow continues into early Monday no snow will be able to stick in Powell Valley vs. heavy snow at elevations over 3000 feet just above within the High Knob Massif ( especially if a rain-snow melting zone develops along Powell Valley as documented in past events* ).

*That would be a TIM Circulation ( a Thermally Indirect Mesoscale circulation that I have documented in research during past decades ).  Uncertainty associated with how long such a flow will be sustained is the main reason I am not highlighting this currently, but it could be a notable player in this system and I may update later if it forms.

Ironically, the easiest part of this forecast is currently out in the 48-72 Hour range when moderate-strong NW upslope flow will combine with bitterly cold air aloft to generate a setting favorable for whiteout snow squalls…especially in locations along & west of the Cumberland-Allegheny Front.

Atmospheric parameters currently being forecast are prime for intense snow squalls, with whiteout conditions and the potential for significant accumulations of low density snow such that this must be closely monitored and updated as cyclogenesis occurs over the western Atlantic Ocean.