My Forecast For Today ( March 4 )

State Route 619, Routes 237 & 238, as well as others, are icy and snow covered in upper elevations of the High Knob Massif.  Use caution if traveling overnight into morning in this area and at other elevated locations in the area which had sticking snow.  Visibility ( with freezing fog ) is also very low above 3000 feet.  

Otherwise, with temperatures at or below freezing, patches of black ice could form on other surfaces and with freezing fog across upper elevations above 3000 feet.

Overnight Into Mid-Morning

A chance of flurries & light snow showers.  Drizzle possible.  Cold & damp.  Winds shifting NW to 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.  Freezing fog with rime formation at elevations above 3000 to 3300 feet.

Mid-Morning Through This Afternoon

Any flurries-drizzle ending.  Chilly.  Decreasing clouds by mid to late afternoon.  NW winds 5-10 mph, with higher gusts, on mid-upper elevation mountain ridges & plateaus.  Temperatures varying from lower 30s to the lower-middle 40s, coldest at highest elevations.  Wind chills in 20s & 30s.

Tonight Into Saturday Morning

Chance of an early evening sprinkle or snow flurry.  Partly to mostly cloudy in the evening with increasing mid to high altitude clouds overnight into morning.  Winds SW-W at less than 10 mph in most places ( a few higher gusts along mid-upper elevation ridges ).  Temps in the 20s to lower 30s.

 

Weather Discussion ( March 3-4 )

Afternoon Update

Many mountain wave induced breaks have occurred amid an otherwise persistent overcast this afternoon, with temps varying from around 30 degrees on High Knob to the lower 40s in portions of the Clinch & Powell river valleys.

The only change in my forecast being to skies for this evening, with partly-mostly cloudy conditions now expected with just a chance for a passing sprinkle or snow flurry.

Breaks have occasionally illuminated the beautiful rime capping the sprawling High Knob Massif.

Mountain wave breaks began developing by mid-morning and have increased this afternoon.

Snow depths of around 1″ were reported above 3200 feet in the High Knob Massif this morning, from 0.5″ measured in High Chaparral by my friends Joe & Darlene Fields to about 1″ or a bit more at the summit level.

My friends Wayne & Genevie Riner measured 0.3″ of snow at their official NWS station on Long Ridge of Sandy Ridge as PM temperatures struggled to reach the middle 30s.

The PM Max officially reached 39.7 ( 40 ) degrees in Clintwood.

 

My Overnight Discussion

Although around 1″ of snow looks to have accumulated at highest elevations in the High Knob Massif, there was little sticking in most places as the mountain area got caught in between a snowband to the north and heavy rain-storms across the Deep South.  That was the main reason I did the afternoon downgrade for this area.

Reference my 030316 Forecast for more details on the past day.

When I saw that setup I knew this area would be getting limited snowfall with air sinking adjacent to the snowband toward the north and around the rain-thunderstorms to the south.

Up to 7″ of snow has been measured within the main band of snow that set up over northeastern Kentucky amid the JKL National Weather Service Forecast Office’s coverage area, with public reports as high as 9″ .

Note the U.S. GFS Model forecast on the 1:00 AM Thursday run did not even have any snow forecast over the area that got the most snow.  The following 7 AM run ( below ) was not much better.

The 7 AM Thursday run of the NAM Model group did have a somewhat better handle on placement of the snow, with  the northeastern Kentucky snowband appearing ( although still forecast to be much weaker than it turned out to be ).

It was not until the snowband was already forming that the high-resolution NAM 4 KM Model finally was able to resolve it somewhat better; although, still not precisely.

The European Model did the best of all models as it did pick up on the northern-northeastern Kentucky snowfall enhancement, but had struggled with placement and amounts.  Most importantly, for this area, it over-estimated snowfall along the mountains at the expense of snowfall in the lowlands of the foothills.

I show the above to illustrate the problems that models have trying to resolve some systems ( especially those possessing separated pieces of energy and/or amid a transitional state before intensification.  This weather system had both these factors going, and more ).

Last night I made an excellent forecast based upon the data at hand, including that of the European Model, which I had used along with the high-resolution NAM to develop a elevation zone break-down in amounts.

The problem, of course, precipitation never did develop as it was forecast by models over this area as atmospheric compensation had to occur for all the air converging at low-levels and rising upward through the atmosphere to crank out snow amid the lowlands to the north.

When air converges and rises over one region it typically will sink into adjacent zones in order to conform to the atmospheric-fluid dynamics principle summarized by the basic Law Of Conservation Of Mass.  This occurs all the time locally, with showers or squalls of rain-snow and throughout the convective ( thunderstorm ) season.  It also is forced throughout the orographic season by the mountains, with formation corridors possessing rising and sinking air.  Remembering always, of course, that this is four dimensional in nature ( i.e., it possesses two horizontal wind components, a vertical wind component, and time ).

Looking ahead, one more weak system passes later Saturday before a significant warming trend to spring levels kicks in to dominate next week.  Eventually, this will crank up the spring thunderstorm machine.

( No, I do not think this is the end of winter.  With good chances for more accumulating snow, especially at higher elevations, before the record books close on this Winter Season of 2015-16 ).

Have a great TGIF.