020416 Forecast

My Forecast For Today ( February 4 )

ALERT For High Stream Levels Along Steep Creeks Draining The High Knob Massif And On Mainstem Rivers.  Caution Is Advised Around All Streams.

Overnight Into This Morning

Mostly cloudy & colder.  Cloud bases obscuring highest elevations in freezing fog ( riming ), mainly above 3500 feet into morning.  Small chance of flurries.  SW winds shifting WNW to NNW at 5-15 mph, with higher gusts across mid-upper elevation mountain ridges.  Temperatures varying from lower 20s along upper elevation ridges to the upper 20s to lower 30s by sunrise to mid-morning ( milder amid valleys of the Clinch, Powell, Holston rivers ).  Wind chills in the 10s & 20s into morning ( coldest at highest elevations ).

This Afternoon

Partly to mostly cloudy.  Seasonably cold.  Light NW winds generally less than 10 mph.  Temperatures varying from upper 20s at highest elevations in the High Knob Massif to the upper 30s to lower 40s.  Wind chills in the 20s & 30s, except some upper 10s in gusts at highest elevations.

Tonight Into Friday Morning

Becoming cloudy with a chance for flurries and light snow showers.  NW winds 5 to 10 mph, with higher gusts, below 2700 feet.  NW-NNW winds 10-15 mph, with higher gusts, along mountain ridges above 2700-3000 feet ( low clouds with some riming possible at highest elevations ).  Colder.  Temperatures dropping into the 10s to lower 20s, with lower 10s at highest elevations.  Wind chills falling into teens, except single digits above & below zero at highest elevations overnight into morning.  Any accumulation varying from a dusting up to 1″ .


Weather Discussion ( February 3-4 )

Morning Update

My forecast is on track, with only slight changes for the afternoon and tonight.

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

Cloud bases have just been dragging across highest peaks through the morning with riming ( especially amid high gaps where air is accelerated upslope ).

Nora 4 SSE - Elevation 2650 feet
Nora 4 SSE – Elevation 2650 feet
Morning temperatures have varied from low-mid 20s atop the High Knob Massif and Black Mountain to lower 30s in Norton-Wise and along the adjacent ridge communities of Wise & Dickenson.
NASA Visible Image
NASA Visible Image at 9:30 AM – February 4, 2016
Low clouds are extensive, with a few breaks.  I have changed the afternoon wording slightly to reflect the potential of more clouds and added a dusting up to 1″ potential for tonight ( for upslope locations as a upper air disturbance crosses the mountains ).
Big Stony Creek Stream Levels
Big Stony Creek Stream Levels Up To 8:30 AM This Morning ( Feb 4 )

Water levels remain high on steep creeks and mainstem rivers, so my Caution ALERT remains in effect today.


My Overnight Discussion

The main weather focus has been on heavy rain and strong rises on creeks and rivers during the past day.  Steep creeks draining the High Knob Massif continue to roar tonight but levels have peaked according to stream gauges.

Big Stony Creek Stream Gauge
Big Stony Creek Stream Gauge At 11:45 PM on February 3, 2016
The Big Stony Creek gauge is excellent to also judge levels on the South Fork of the Powell River, Little Stony Creek, and adjacent steep creeks in the massif.  The main exception being during the summer season when heavy rain events can be concentrated in local drainage basins ( and not extend across the entire massif ).  Any time water levels are within or above Yellow Alert stage the volume is significant and creeks roar ( a pounding roar develops when the level goes above Red Alert stage ).
Forecast For Clinch River At Speers Ferry
Forecast For Clinch River At Speers Ferry

The Clinch River, downstream of the massif, is forecast to crest during the morning to noon period today ( latest MRX projections being just below minor flood stage ).

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

Outside of heavy morning rains, Wednesday afternoon was very nice with temperatures becoming even milder than expected as low clouds broke relatively fast into mid-day.  An array of high-altitude clouds created a nice sunset.

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

Focus is now on a return to seasonably cold conditions with mainly dry weather during the next few days.  An upper air disturbance will be pushing across the mountains Thursday evening with limited moisture.  Some flurries and/or snow showers will be possible as air turns colder than today.  Any accumulations currently look to be light as streamlines will be from mid-continent and lack a good moisture source.

*A chance exists for wave development over the western NC area, with movement to and off the Atlantic Coast.  Any snow along the mountains currently looks limited late tonight into Friday, but this will be something to follow on new forecast model runs.
NAM Model 500 MB Vorticity Forecast
NAM Model 500 MB Vorticity Forecast at 10 PM Thursday ( Feb 4 )

The shift back into cold air is well underway now across the high country, on NW upslope flow and increasing low level moisture, and should bring cloud bases down onto highest crestlines from the High Knob Massif to Black Mountain.

Black Mountain MesoNET
Black Mountain MesoNET at 1:00 AM Thursday – February 4, 2016
Temperatures have now dropped below freezing along highest crest lines, with gust chill factors in the 10s, on NW-NNW winds.
European Model 850 MB TEMP & Surface Analysis
European Model 850 MB TEMP & Surface Analysis – 7 PM Wednesday ( Feb 3 )

Bitter air and prospects for snow increase into next week but forecast models have much work to do in order to figure out a complex pattern featuring several jet streams and a array of embedded disturbances.  Axes of main snowfall currently vary from along the mountains to the Atlantic Coast ( from South Carolina to north of the VA Capes ).  Perhaps it will be both, but time will soon tell more.

For a review of recent winter photographs reference this section of the High Knob Landform website ( more to come in days ahead ).

Have a great Thursday.