030316 Forecast

My Forecast For Today ( March 3 )

Updated At 3:00 PM:  My ALERT For Any Significant Snow Accumulations Is Cancelled – Some Snow Is Possible Tonight-Friday Morning But Amounts Are Expected To Be Light ( Generally Less Than 1″ ).

A band of persistent snowfall had developed from northeastern Kentucky into western-southern West Virginia and will now be the focus of heaviest snowfall amounts during this event in our region

ALERT For An Accumulating Wet Snowfall Developing This Afternoon Into Tonight – All Snow Is Likely Above 2500 to 3000 Feet, With A Mixture Possible Below 2000 to 2500 Feet…Before Changing To All Snow.

Rain and snow will develop across the area this afternoon into tonight, with the elevation of the sticking snow level yet to be determined for this afternoon in locations along and north of the High Knob Massif.  A mix or rain will be likely in the Powell Valley to Big Stone Gap corridor on downsloping winds off the High Knob Massif.

Overnight Into This Morning

Partly-mostly clear evening skies giving way to increasing clouds into morning.  Light SSE-SSW winds at generally less than 10 mph on mountain ridges below 2700 feet.  Winds S to W at 5-15 mph on upper elevation ridges.  Temps varying from the upper 10s to the upper 20s, with readings tending to rise into morning, especially at high elevations.

This Afternoon

Cloudy with rain & snow developing.  All snow above 2500 to 3000 feet.  A mixture possible at lower elevations, with a mixture likely within the Powell Valley to Big Stone Gap corridor.  Winds ESE-SSE at 5-10 mph, with higher gusts, along middle elevation mountain ridges & plateaus.  SE-S winds 10 to 15 mph, with higher gusts, in upper elevations.  Temperatures in the 30s to around 40 degrees before a drop into the 20s to low-mid 30s after precipitation onset.  Wind chills in the 10s & 20s exposed mid-upper elevation ridges.

Tonight Into Friday Morning

Snow at mid-upper elevations.  A mix changing to all snow at lower elevations.  Winds becoming NW-NNW at 5-15 mph, with higher gusts, overnight into morning.  Temperatures in the 20s to lower 30s.  Wind chills in the 10s and 20s on exposed mid-upper elevation mountain ridges.

Snowfall Forecast – Thursday PM to Friday AM

1″ or less at elevations below 1500 feet

1″ to 2″ at elevations of 1500-2500 feet

2″ to 4″ at elevations of 2500-3500 feet

4″+ possible at elevations above 3500 feet

Target Snowfall of 2″ in Norton-Wise ( +/- ) 1″ spread potential.  This implies a general 1″ to 3″ of snow possible.  Locally higher amounts will occur if precipitation is all snow, while amounts could be less if more mix occurs.
*If an easterly component to the low-level flow develops, snowfall will be less than 1″ in the Powell Valley to Big Stone Gap corridor and into portions of Lee County.  If a TIM Circulation should form precipitation amounts could be enhanced in the Norton-Big Stone Gap corridor, with more snow on the cold side of the boundary and enhanced rain on the warmer, sinking air side of the circulation.


Weather Discussion ( March 2-3 )

My Afternoon Update

Precipitation echoes have been over top the area since early this morning but little to nothing ( even sprinkles or flakes ) have reached the surface.

High Knob Massif Webcam
High Knob Massif Webcam – University Of Virginia’s College At Wise

Much of the Mountain Empire has been caught in between main precipitation bands, one to the south with rain-storms and another which has set up from NE Kentucky into West Virginia.  So I have cancelled my ALERT for any significant snowfall.  The Winter Weather Advisory officially remains in effect into Friday AM.

Regional Doppler Composite At 3:08 PM
Regional Doppler Composite At 3:08 PM

The latest high-resolution NAM 4 KM Model seems to have picked up on the trend and placement of snowfall amounts.

NAM 4 KM Model Total Snowfall Forecast Next 18 Hours
NAM 4 KM Model Total Snowfall Forecast Next 18 Hours
“You have to know when to hold them, and when to fold them,” says Kenny Rogers, so in this case I am folding with respect to significant snowfall.  Some snow may still occur but generally accumulations are likely to be less than 1″ in most places.

The forecast in words will remain unchanged, just snowfall amounts will be much less than expected.  This is the update I was somewhat expecting from last night ( to either go up or down in amounts, amid this middle zone ).


My Overnight Discussion

Reference my 030216 Forecast for more details on the past day.

Flurries and snow showers developed overnight as colder air poured into the mountains with just enough sticking to coat roadways across the High Knob Massif and in a few other elevated locations.

State Route 706 on Wednesday Morning
State Route 706 on Wednesday AM – High Chaparral of High Knob Massif

Nice rime formed in freezing fog above 3300 feet.

Eagle Knob of High Knob Massif - At 6:59 AM
Eagle Knob of High Knob Massif – Rime & Light Snow – Wednesday AM

Low clouds held tough through much of the day.

High Knob Massif Webcam
High Knob Massif Webcam – University Of Virginia’s College At Wise

Clouds finally broke up for some late afternoon sunshine following more flurries, rime, and a nasty cold day that found temperatures struggling to reach 20 degrees at the top of the high country and 30 degrees in Norton-Wise.

High Knob Massif Webcam
High Knob Massif Webcam – University Of Virginia’s College At Wise

A gorgeous, albeit cold, sunset graced the mountains.

Forecast models continue to struggle to resolve the track and precipitation amounts associated with a southward tracking clipper-like system which begins to spread moisture across the mountains by Thursday PM.

Regional Doppler Composite At 12:58 AM
Regional Doppler Composite At 12:58 AM Thursday – March 3, 2016

The forecast on this system is more difficult than usual since it remains disorganized and will not be in position to really intensify until it reaches the Atlantic Coast, with SE Virginia and the Tidewater around Richmond looking to be amid the main snowfall target zone by late Thursday Night into Friday morning.

The amount of snowfall observed locally this afternoon into Friday morning will be dependent upon moisture and wind direction, which will influence the temperature profile amid lower levels of the atmosphere ( air will be cold enough for all snow across upper elevations with only the amount there being unknown ).  The forecast may need to be updated later today as development of this system is followed over time.

Longer Term Peek

Conditions will remain chilly into this weekend with another weak system passing during Saturday.  This will keep relatively chilly temperatures in place with the real surge of warmth not coming until Monday into Tuesday as Atlantic ridging and western-central USA troughing develops.

European Ensembles MEAN 500 MB Height Anomalies
European Ensembles MEAN 500 MB Height Anomalies Forecast Days 1-5
A pattern opposite to that recently observed will develop next week with troughing to the west and ridging along-just off the East Coast of the USA.  This is a spring thunderstorm pattern, which will need to be closely followed over time.
European Ensembles 500 MB Height Anomalies
European Ensembles 500 MB Height Anomalies Forecast Days 6-10

Eventually, next week, a large upper trough will set up a return flow from the Gulf of Mexico and increase the potential for showers & thunderstorms.

A major outbreak of severe thunderstorms may develop west of the mountains, along with an excessive rainfall potential.

Have a great Thursday.