Clear & cold. WNW-NW winds 5-15 mph, with higher gusts, along middle elevation ridges and plateaus below 2700 feet. Winds NW at 10 to 20 mph, with higher gusts, on mountain ridges above 3000 feet. Temperatures in the 10s to mid 20s, coldest in sheltered valleys and along highest ridges. Wind chills 0 to 10 degrees on exposed ridges in upper elevations to the 10s and lower 20s.
Monday Afternoon
Mostly sunny. Continued chilly. NW winds 5-15 mph, with higher gusts. Temperatures varying from upper 20s to low 30s in upper elevations to the upper 30s to lower 40s.
Monday Night Into Tuesday Morning
Becoming partly cloudy ( high clouds ). Winds NW-N 5-10 mph, with higher gusts, on mid-upper elevation mountain ridges. Temperatures varying from 10 to 15 degrees in the colder valleys ( locally even colder ) to middle 20s to lower 30s ( warmest on exposed ridges where temps will be near steady or slowly rising ).
Tuesday Afternoon
Partly-mostly sunny ( high clouds ). Light & variable winds. Near inversional conditions developing with temperatures varying in the upper 30s to upper 40s ( some valleys being nearly as cool or cooler than adjacent ridges ). Milder in some spots, especially into the Great Valley.
Tuesday Night Into Wednesday Morning
Increasing clouds into the overnight-morning. Winds S-SW at 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from 20s in colder valleys to the mid 30s to low-mid 40s on exposed ridges.
Weather Discussion ( Chilly )
Monday PM Update
High Knob Massif Webcam – University Of Virginia’s College At Wise
My afternoon update is to zero in better on MIN temps tonight with 10 to 15 degrees expected in colder valleys to contrast with milder readings on exposed ridges ( no place; however, will feel mild ). Local MINS may actually dip just below 10 degrees in coldest upper elevation valley spots if high altitude clouds do not thicken into the overnight.
*The coldest MIN temperature recorded in high valleys so far this autumn has been 8 degrees on the morning of November 13.
NASA Visible Image On Monday – November 21, 2016
I took a NASA visible image today to illustrate how close sticking snow came to the NW upslope flow corridor of the Mountain Empire, highlighting the sprawling High Knob Massif and Mount Rogers for reference points. Smoke plumes from the larger fires remain visible as well.
Previous Discussion
Following the first widespread snowflakes, sleet pellets, and a bit of riming at highest elevations, the air mass is seasonally chilly. Although winds remain gusty on high ridges, deep valleys have decoupled ( winds calmed ) to allow sheltered valleys & hollows to join high ridges as coldest places into Monday morning ( locations between these extremes, in thermal belts, being “milder” ).
*The above being especially true for the Russell Fork & Levisa Fork basins, and locally in the Upper Tennessee Basin, where terrain is highly dissected. Cross-barrier speed up flow will prevent this for mostly all locations along the eastern slopes ( Blue Ridge ) where turbulent mixing will be enhanced into Monday morning.
Black Mountain MesoNET Observations
Wind chills Sunday evening have occasionally dipped to between 0 and 5 degrees along highest ridges with air temperatures around 20 degrees. This is part of a sub-freezing period that will last into Tuesday in some places amid upper elevations of the High Knob Massif ( the longest sub-freezing period since last winter ).
With low sun angles it is getting that time of year in the mountains where temperature inversions by day, not just during night, become possible at times. Tuesday will offer conditions at least favoring near inversional temps with some hollows-valleys being nearly as cool, or locally cooler, than adjacent ridges ( temperatures typically decrease with increasing elevation during day-time hours, with opposite or inversional conditions often being common at night ).
European Ensembles MEAN 500 MB Height Anomalies Forecast – DAYS 6 to 10
Finally I can say that I really like the look of the extended period upcoming during the next 1 to 2+ weeks, with rising pressures across the Arctic Basin and decreasing heights and pressures over Middle Latitudes that will be working together with a southward developing baroclinic ( temp ) zone to push the MEAN jet stream and storm track south.
While a mid-November change in the pattern has occurred, as I had been expecting for some time, everyone knows that what we are really seeking is precipitation to ease forest fire conditions and help depleted mountain lake water supplies. This pattern is going to now make that possible as it continues to evolve during the remainder of November into early December. Finally!
European Model Mean Sea Level Forecast At 7 AM on November 30, 2016
The above forecast chart at DAY 10 is certain to change, but the synoptic-scale trend is very clear with a much better setting for precipitation events ( both in the frequency of their occurrences and in amounts ) as November wanes and December arrives. This shows up well, with highest confidence, on MEAN ensemble charts such as that of the 51-Member European group.
This means increased chances for needed precipitation with a strong signal for another major storm system showing up by the end of November. The difference this time, with a southward suppressed jet stream, being the chance to tap Gulf of Mexico moisture for enhanced precipitation totals.
Although this most recent event was by no means a drought buster or even a good dent maker, the general 0.30″ of precipitation that was received in the High Knob Massif area was more than models forecast. I expect this trend to continue as more and more events develop winds that push against the mountain terrain, cranking up the orographic forcing which helps make the massif area the wettest in Virginia over the long-term.
GFS Ensemble Total Precipitation Forecast – Next 16 Days
The 21-Member GFS ( USA ) Model ensemble group shows the basic agreement in increasing precipitation amounts across the eastern USA during the next couple of weeks. Most importantly, the much more stable and reliable 51-Member European group supports this trend. In addition, the Canadian Ensembles as well as the Japanese ( JMA ) Model are also on board. Details of specific events, of course, to be worked out as time passes.
I do not go by any single model, but instead like to use ensembles and their MEANS ( especially the European ), with currently very good agreement among global model ensemble groups about this increasing precipitation trend.
*I am not legally allowed to show ( display ) the European Model or its Ensembles precipitation graphics, only the most basic charts from it.
