Event 1 Done, Event 2 and 3 Ahead

December 11, 2025December 11, 2025 / alleghenymountainsweather / Leave a comment

December 11, 2025 1:21pm

Event 1 of 3 finishing up this afternoon and focus goes to a weak Event 2 and a more potent Event 3.

Event 1

General amounts of 2-5″ north(Garrett ,Preston in to Pa) Elevations of 2500-2700′ and under struggled through yesterday afternoon in to the evening to accumulate snow due to very slightly milder temps than expected. Literally talking 1-2° and snow rates at 2500-2600′ weren’t quite heavy enough in most of the region to overcome the 34°+/- surface temps. In some instances west, it was heavy enough to do so at times. Areas below 2500′ fought liquid awhile through the afternoon. I had .2 moisture that was primarily all snow falling, but that couldn’t quite get to accumulating due to temps. This impacted totals by 2″+/-. The 4-7″ call in reality came in a bit high due to that, but some areas still managed to clip the low end of expectations.

As you went higher up, Elevation aided in just slightly colder in Wv above 3400-3500′. The 5-10″ call wasn’t bad here.

Moving Forward

●Friday am through Friday Pm

GFS

Euro

This event looks like it will dive further south. The GFS a bit further north vs the Euro.

1-3″ Snowshoe, coating to 2″ Canaan, inch or less Garrett. Not a big event of note. Storm track loves this route the last few weeks.

●The more potent event comes in Saturday PM through Sunday a.m

Gfs

Euro

This event likely will warrant some Winter Weather Advisories or Winter Storm Warnings.

A Widespread 4-8″ looks likely and that comes without fighting any marginal temperatures to hinder progress. Speaking of temps. It turns very cold Sunday night. Single digits with sone Wv tops squeaking below 0 with colder windchills. Windchills of -5 to -15 across most of the Alleghenies with -15 to -30 across the higher exposed Wv tops Sunday night.

A moderating trend midweek next week. How much, how do we will towards Christmas…well strong indications of milder weather, with some cold fighting back at times. Lots of mild air to the south, cold shunted north that can be driven back in with high pressures passing north. Exactly how things will play out has lots of question marks.

December 10, 2025

December 10, 2025December 11, 2025 / alleghenymountainsweather / Leave a comment

December 10, 2025

Forest Service Cam offline since 6/24/21

Dec 10(Wed)

Cloudy, windy morning. Then some snow, areas of light rain midday on. Some areas it snowed during the afternoon at 34-35° with no accumulation. Some areas mainly below 2500′ saw light rain. After nightfall and the passing of the cold front, accumulations began to lower in elevation.

Bittinger 2NW Valley

precip .21

sf .1 , sd 2.0 7am, sf season 9.4

Bittinger 2NW Valley afternoon. Snowed like this most of the afternoon. Temps just not allowing for accumulation

Bittinger 4H

Top of Wisp

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Mosser Rd 9pm

Canaan Heights/Davis 3SE

Climate Reference Network Canaan

Cabin Mt at Bald Knob

Cabin Mt-Western Sods

Bear Rock-Dolly Sods

Canaan Valley Refuge

Dobbins High Bog Sods

Spruce Knob

Snowshoe

Mt.Davis

Flight 93

Elkins Airport

Site Comparison

Bittinger 2NW Valley, Bittinger 4H, Garrett County Airport, Mt.Davis

The Valley vs Cabin Mt

Canaan area temps

Sods Plateau

High Ground Comparison

Up High and Down Low

Up High, High Valley, Low Valley

The Valleys

Wv High Ground Cold Spots Vs DCA

RTMA

Radar

Satellite

Flow

Current Surface Features and 500mb Height Anomalies and Flow

Oakland

Cranesville

gaining a little Elevation over the Mt 32°

The Yough & Sang Run at 35°

Webcams

Upslope Event 1of 3 with Blizzard Conditions

December 10, 2025December 10, 2025 / alleghenymountainsweather / Leave a comment

Upslope Event 1of 3 with Blizzard Conditions

December 10, 2025 7:31am

A BALMY morning relatively speaking if you are across the high ground and west. South winds blasting over the area along with some cloud cover.

Its colder in the panhandle of Florida this morning vs some of the high Alleghenies. Clear skies, calm winds there, that leads to a good night of radiational cooling east of the mountains and a bit further south. Let’s look locally at the east side vs west side of the Alleghenies. Cumberland 20s, Garrett County Airport near 40, Morgantown in the 40s. Thats calm, separating from the air mass aloft to the east. Meanwhile the disturbed air, associated with our incoming weather is in play over the high ground.

Cold east this morning, mild over and west of the Alleghenies

Now throw in some good snow-cover with those clear skies in the south east side of the Alleghenies and its even colder this morning. Teens vs mid 40s on the west side of the Alleghenies.

Not a unforseen or rare thing to watch that play out.

Courtesy of high pressure south and the low pressure of the clipper system coming across the southern. Great Lakes area.

Low pressure northwest-counter clockwise flow= southerly winds. In this case gusty southerly winds.

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Its too warm to snow? Theres a pretty good lapse rate and more low level dry air in place. Meaning its colder as you go up, dry air has further room for evaporarational cooling. It can initially snow to the surface/graupel/snow pellets at 40°. Courtesy of dry air. That dry air is also a reason this morning at 40°, limited if any snow melt has occured. As the dry air moistens up at the surface and aloft, it helps lower the surface temps and as precip falls its also cooling the lower levels,,especially with any heavier rates. So initially the snow today above 2000-2500 will be a wet snow. 32-34° surface. Any lulls in action, temp may flux up a degree and with saturation the surface can even briefly melt back what has fallen.

K2G4 Garrett County Airport (2933′)vertical profile. Dry low levels this morning . Up a few thousand feet, temps below freezing.

as the low levels saturate they cool, as well as the surface gets down to near freezing as precip commences..

Above 3200-3500′ temps should come back down to and below freezing and no issues of tetering the freezing mark as it snows today. As we go evening in to the overnight and the winds shifting west, northwest colder air comes in. Snow ratios increases. A 10 to 1 today goes 20+ to 1 tonight. A lighter snow in terms of density and is mire readily blown about on strong winds gusting 40-50+mph. Thus conditions look doable of 1/4 or less visibility, 35+mph winds, with snowing and blowing occurring for 3 or more hours. We have had numerous like events in years past that have not been issued per the letter of criteria and now they are. So, to stress, its not the Blizzard of 93 coming. However poor conditions with whiteouts are expected.

Now let’s look at the 3 upslope event per the Euro

event 1 today and tonight in to Thursday

my thoughts for the current event remain unchanged. Lean low to mid range and a good performance can reach the top end

now off the Euro for event 1

Event 2 Friday-Friday night- more of a diver and weaker vs 1 and 3

Event 3 Saturday night-Sunday

3 systems by the time we get to Monday that may tally 10,12-20″ across the high ground. Being windblown, you will not have those amounts on the ground. Total snowfall accumulation for multi day and multi events is not the same as snow depth. Due to a variety of factors.

Frigid air late weekend, early next week looks to rapidly modify by midweek and lots of mixed signals as we head towards Christmas.

December 9, 2025

December 9, 2025December 10, 2025 / alleghenymountainsweather / Leave a comment

December 9, 2025

Forest Service Cam offline since 6/24/21

Dec 9(Tues)

Clouds a.m, few fine stray a.m flakes . Clouds-Sun pm.

Bittinger 2NW Valley

precip 0

sf 0 , SD 2.0″ sf season 9.4

Bittinger 4H

Top of Wisp

Canaan Heights/Davis 3SE

Climate Reference Network Canaan

Cabin Mt at Bald Knob

Cabin Mt-Western Sods

Bear Rock-Dolly Sods

Canaan Valley Refuge

Dobbins High Bog Sods

Spruce Knob

Snowshoe

Mt.Davis

Flight 93

Elkins Airport

Site Comparison

Bittinger 2NW Valley, Bittinger 4H, Garrett County Airport, Mt.Davis

The Valley vs Cabin Mt

Canaan area temps

Sods Plateau

High Ground Comparison

Up High and Down Low

Up High, High Valley, Low Valley

The Valleys

Wv High Ground Cold Spots DCA

RTMA

Radar

Satellite

Flow

Current Surface Features and 500mb Height Anomalies and Flow

Cranesville

The Yough at Sang Run

UPSLOPE ROUND 1 WEDNESDAY-THURSDAY

December 9, 2025December 9, 2025 / alleghenymountainsweather / Leave a comment

UPSLOPE ROUND 1 WEDNESDAY-THURSDAY

December 9, 2025 8:41am

After a back to back central and southern Alleghenies winter events, the entire Allegheny region and especially the upslope region gets to join in on the action Wednesday in to Thursday. (Not only Wednesday-Thursday as there is more beyond)

A low pressure system passing north on Wednesday will have push moisture in across the Alleghenies. A southerly push of air with the associated warm front will stabilize temps 28-34 overnight and rise 32-36 Wednesday morning. As moisture moves in the entire column to the surface should rapidly cool to produce primarily all snow in spite of the “mildish” start relatively speaking. Surface temps remain steady through late day as the associated cold front swings through.

1- Expect snow morning through afternoon with temps steady upper 20s Wv tops, low 30s 2400-3000′. Initial daytime accumulation looks to be best above 2400′. Strong southerly winds in the morning shifting westerly midday. Gusting 35-50mph+

2- as the cold front crosses. A burst of snow, winds shifting W to NW and upslope snows increase. Snow ratios increase. . Winds gusting 40-55mph across the tops. Can we sustain a period to qualify as blizzard conditions. That is possible and its not out of the realm a blizzard warning could be issued across the higher Wv regions.

3- lingering but decreasing snow on Thursday.

My own thoughts on the event snow totals look like

The NWS and modeling is per similar

Lets run the Euro for this event:

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The experimental RRFS model last year in these setups did pretty darn well with snow ratios. Snow Water Equivalent. It starts out 10 to 1. Many think thats a basic rule that 10″ of snow is 1″ of liquid. Across the high ground, and especially with upslope which makes up a good portion of the average annual snow. Ratios are generally much higher. In this case by Wednesday night in to Thursday a.m. 20 to 25 to 1 is likely common.

here is the RRFS Ratios. Showing is as I saw it perform well multiple times last year with this setup.

When the ratios increase, as does forecast error and needed snow range.

take this for example. Modeled hourly precip output. Say you are getting .05 to .1 in an hour at 20 to 1. There you picked up 1-2″ of snow. Say the model was off that little bit and no precip occured that hour. Totals may expect to be lowered from a simple .05 to .1 liquid. You dont think about that minimal liquid in a warm weather rain event. Say that .1 ends up being a lengthy squall and you get .2 in an hour at 15 to 20 to 1. There you got blasted with S+ 3-4″ of snow in an hour. Higher ratios greater the error. Now toss in 40-50mph winds with those higher ratios. It obviously blows it about and even in semi protected areas it takes out the fluff(air) of the higher ratio and depending where the observer is located and his measuring technique. Widely variable reports may be seen. Thus, snowfall reports historically are the least valuable data set.

And in this example of THE RRFS it ranges around 5″ for the Garrett County Airport. Example given how that can be fluxed up or down.

other model output:

6z Euro(personally I think some of these numbers get beat)

6z GFS

Blended Model

as we go Friday through the weekend, 2 more events to watch

Friday

Sunday

Its very possible by next week this time a total week accumulation of 12-24″ across the high ground is possible.

This at times especially late weekend may be accompanied by below 0 air temps. So there are some extremes associated in here also. A very wintry week ahead.

NWS WATCHES

There is ABSOLUTELY NO reason eastern Preston shouldn’t be included in a upslope event. Aurora, Terra Alta, Cranesville all do very very well in upslope events. Even up along the Laurel Highlands and those may be added in today. Hello Pitt, State College.