Moisture incoming. The leading edge is running in to dry air. Virga=not reaching the ground. It’s simply working
1 to moisten the lower levels(it has in some areas, especially southern Alleghenies and west side)
2 some evaporational cooling will occur as it does
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We have the big cold dry strong High pressure in New England
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A visual of the winds at the surface around that
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5000′ aloft winds out of the SW, milder and moist. Once you are across the high ground west of the wedge over the Allegheny Front, this influence is dominant.
–Bear Rocks 26, Bald Knob 34. I’d expect Baldy to drop awhile as precip gets going. –
and up in Pa
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Temps through the day off the Euro
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Using the HRRR Precip type. Last year it showed marked improvements. Nothing however will be exact. The sleet/freezing rain zone can wobble east or west.
The snow zone I really like Frostburg, Cumberland, Bedford for 2-5″/3-6. Modeling puts out .6 liquid and the brunt occurs in believe there as snow. We shall see.
-The HRRR snowfall. Western portion and southern portion i think mixes in more sleet to limit totals. Definitely like the areas me times above. Remember to watch that Blue Knob cam today
HRRR sleet. I think any portion of this sleet zone leans more freezing rain. How much sleet occurs will impact ice accretion. Sleet gets recorded as snow, ice gets recorded as ice accretion
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The HRRR limits freezing rain too much and other modeling looks over done. The euro below. The west edge of this goes to plain rain today. Melt off. The highest totals in here, saw in half.
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THE NWS WARNINGS
what I dislike about this. Allegany County Md will have much more wintry impact vs portions of Eastern Tucker in the winter storm warning. Much more than eastern Randolph. Same goes for Bedford. It looks more severe across the highest locations, even west of the Allegheny Front and it won’t be.
Winter Storm Watches have expanded for Sunday, we’ll go to that in a moment. First out the door conditions this morning
A very cold start this morning across the area valleys, and “less cold” on the ridgetops.
▪︎Temps mainly teens to upper 20s and low 30s on the high Wv ridges out there on this Saturday morning.
Davis at 12, Bearden Knob 30, 9 at the Valley station and 30 on Cabin Mt–
Views on the morning:
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A fairly tranquil Saturday in place. Temps remaining cold across the high ground and east. Milder west. That theme continues Sunday with the incoming weather event. That weather event had watches and advisories out across the region. I strongly expect these to expand east in some form or fashion. A bit shocked that they are not already as THATS the prime zone. Some of the area under watches may see limited impact, and areas currently without a much more significant impact.
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Surface Map Sunday Morning
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-afternoon
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That cold dry High, clockwise winds funneling in cold dry air at the surface.
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All the while the encroaching Low with counter clockwise winds pushing milder, moist air up and over the surface cold.
5000′ winds and temps below
A visual of the Wedge
As the dry cold air rises it cools up the Allegheny Front, evaporational cooling occurs as well.
The wedge gets more shallow and eventually dissappear as you go west under the entire column is above freezing. Eventually the mild air takes over the highest areas of the Allegheny Front, leaving the 2800-3000 sector north the coldest. Then the final step will see all the high ground rise to 35-40 while the low protected valleys east, while above freezing remain chilled the longest.
Lets do a side by side. The surface temps left, 5000′ temps right. Look at that. At 5000′ winds from the low pressure out of the SW. Look at the temps at 5000′ . Now compare to the left, winds at the surface out of the ESE undercutting and riding up the Allegheny Front and wedging west. That wedge gets narrower and narrower as you go west.
The areas you see surface to 5000′ above freezing would be rain. Areas you see 5000′ above freezing and the surface below, you’d see sleet or freezing rain depending the depth of the warm and cold layer. Areas you see both layers cold, the column would support snow. That’s mainly eastern Alleghenies and east of the Allegheny Front. I really like that Cumberland to Bedford to Altoona thump.
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A look at the soundings displays the above visual
-Garrett County Airport. Mild surge aloft. Cold at the surface. Again the surface here can run 28 with sleet or freezing rain while Cumberland is 32,33 and snow. Thats not uncommon. That’s how Cumberland can mostly escape ice as you have the column cold enough for snow, and as the upper air warms enough, the surface is just above freezing when the snow transitions over.
Garrett County Airport below
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-Cumberland, the column holding below freezing.
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The visual off the 6z Euro
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Snowfall off the 6z Euro
The southern area may be suspect, often mild enough layer will work in aloft to change that to sleet.
Sleet zone off the 6z Euro
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Freezing Rain zone off the Euro and likely the western edge of this is brief before the flip to straight rain. Amounts are generally over done on models.
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Again, using the Euro as it looks most like the climatology of these setups as far as precip type boundaries. Other modeling is veering that way. The HRRR is a bit colder and if that played out, the snow would work a bit further west. Adjustments are likely.
The Wedge, over running, (personally under cutting may just as good of a term to describe it) cold air damming. Regardless of the reference, this setup across the Alleghenies is a staple winter weather setup and occurs multiple times each winter. The boundaries are often in the same area. This year with the new Bear Rocks station in play, we can watch that area real time to see just how long it holds vs Cabin Mt.
In these setups, as long as you have the driving mechanism of the High Pressure sitting off to the Northeast driving cold dry air up the eastern Alleghenies, you get adiabatic cooling as the air rises and the process of evaporational cooling with the moisture incoming. That combo helps hold the high eastern Alleghenies cold, as long as you have the main player of that big cold dry high north.
For this post, we will use the ECMWF(Euro) products. It is slightly colder vs other modeling, but tends to handle the setup well.
High Pressure New England
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The clockwise flow of winds at the surface around the High thats sitting in New England. Driving the colder dry air up the east side of the Alleghenies.
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-The modeled dewpoints indicative of that dry air.
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While that’s one player, back to our west is our moisture that will be incoming. Thats accompanied with milder, moist counter clockwise SW winds
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Those SW winds are seen aloft. Lets look at the 850mb(roughly 5000′) winds. As that zooms in at 4pm look at the modeled temps at height. Above freezing aloft and that also would translate down to the high ground on the west side of the Alleghenies and also the lower elevations west. That driving wedge of the the colder dry air gets shallow and completely is gone as you move west of the Allegheny Front. So in your head, vision youre along the eastern Alleghenies at 3000′. You have a driving ESW wind, it’s 29° and that air is rising up the mountain undercutting what’s occuring above you. Up above you at 5000′ there is milder SW winds. The precip is melting in that layer and it’s either refreezing as sleet before reaching the ground or if the milder air sector is broader, it’s remaining liquid and freezing on the surface as freezing rain.
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The modeled 850(5000′) temps for the event. Look what happens in the process along the east side of the Alleghenies. Those 5000′ temps cool further as you get moisturing in that dry air mass lifting up towards the Allegheny Front.
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So, the east side is impacted by the cold dry high. It’s not though as cold as what the high ground along the Central to eastern Alleghenies will be. However the entire column above cools enough that
1- The upper air is cooled just enough to see the entire column below freezing. Therefore you can see snow. This isn’t a setup where we have a departing frigid airmass and you see that cold air sitting there trapped in the deep valleys. Not the case. This setup can feature Cumberland getting snow at 32-34° while at near 3000′ at the Garrett County Airport it’s 29° and freezing rain.
Lets look at that visual of what’s going on up above
-First the Garrett County Airport. I highlighted the freezing point with the blue line. Temperature/Dew Point/Humidity in blue, red, green. Notice as you increase vertically from the surface(that’s the bottom of the temp line) the temperature increases with height. That would indicate likely freezing rain at 4pm Sunday that may battle in some sleet at times as well. The cold is pretty shallow. The surface may be 28-30° at this time but jumps above freezing aloft fairly rapidly.
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Lets hop down to Cumberland at 700′ near the Potomac. The surface sits near 32°, but as you progress in height, the entire column remains just below freezing or very close. Indicating wet snow that may be mixed with a bit of sleet. That may be impacted by precip rates as well. Now if the model is off a degree aloft and at the surface. Straight liquid occurs. Climatology favors snow with the setup for the initial brunt of the precip. Not a major event, but a disruptive one
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Again vision this type of setup(example not for this specific event)
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A look at how the wedge looks from a vertical profile. Depending on how strong the forcing for the undercutting of the dry cold east winds are, depends how far west the wintry makes it. Vision this wedge below advancing east or west. With that you can also see how some of the high 2800-3000′ ridges performs better than a 4000′ ridge when the east flow impact weakens.
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Now let’s translate this system over to a visual using the 6z Euro
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-Surface Temps. Remember you can have slightly warmer temps at 700′ east of the Allegheny Front vs a central and eastern ridge at 2800-3000’+ and have snow down low while sleet or freezing rain up high.
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Again, using the 6z Euro which is a touch colder vs some other modeling. This post isn’t to say this scenario is locked in, it’s definitely a climatological favored look. However variances and changes can occur
– The euro snowfall zone
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-The euro sleet zone. Keep in mind, this isn’t a mesoscale model and the area vs reality can be a bit broader
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-The euro freezing rain setup
In summary, a wintry event is on the table for Sunday. Timing, intensity, how strong the wedge is, is not exactly known. A trend slightly colder, or slightly less cold will impact overall results.
Temps moderate Monday a.m, and whatever occurs begins to melt off. The next potential wintry system looks to be on the table later next week.
For now, enjoy and become fascinated by the unique setup of Sunday. The why of how these systems work holds lots of unique interest that our Alleghenies play a significant role in.
Pockets of snow mostly gone by sunrise. Lots of sun today, but cold and very windy
Bittinger 2NW Valley
precip .08 (since changeover)
year to date precip 50.68
snowfall .2(since 5pm 12/11)
sd 1
snowfall season to date 24.3
Dyacon Data Below
Dates in red due to a Dyacon outage. No data lost. Chart will be corrected at months end. Along with other sites below Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Accident-Bittinger Rd by the old Peat Bog building morning Rock Lodge Rd near The Glades morning Foxtown Rd afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon South end Amish Rd afternoon
Garrett County Airport
Rock Lodge Rd morning. A few skinny squalls last night. One appeared to cross hereRock Lodge Rd morning Deep Creek Lake morning Mosser Rd afternoon
Top of Wisp
Afternoon Afternoon
Canaan Heights/Davis 3SE
7am to 7am data mmts coop BP
Climate Reference Network Canaan
Cabin Mt at Bald Knob
Whitegrass Cam Cabin Mt
Cabin Mt-Western Sods
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Bear Rocks-Dolly Sods
Spruce Knob
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Canaan Valley Refuge
Mt.Davis
no data due to Mid October bear attack on the station
Snowshoe
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Petersburg Grant County Airport
Elkins Airport
Site Comparison
Dy007-Canaan Valley Refuge 3150′, Dy008-Bittinger 2nw Valley 2600′, Dy002-Cabin Mt at Bald Knob 4350′, Dy003-Cabin Mt-Western Sods 4035′, Dy004-Spruce Knob 4820′, Cvpw2-Climate Reference Network Canaan 3380′, KW99-Petersburg Grant County Airport 961, K2G4 Garrett County Airport 2933′, KCBE Cumberland Airport 774′, KEKN Elkins Airport 1985′, KMGW Morgantown Airport 1227′, PMN16-Mt.Davis 3038′, KDCA-Reagan National 15′, G1472 Snowshoe 4500′, F0183 Burkes Garden 3050′, DY025-Bear Rocks 4052′
The Valley vs Cabin Mt
Bittinger 2NW Valley vs Garrett County Airport
Canaan area temps
Sods Plateau
Bald knob directional appeared to remain frozen as the cup anemometer began to operate Multiple 60mph gust at Bear Rocks, 1 at Cabin Mt 2
High Ground Comparison
(Ignore the Black Mt temp blip)
Up High and Down Low
Up High, High Valley, Low Valley
The Valleys
Wv High Ground Cold Spots vs DCA
RTMA
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Radar
Satellite
Flow
Current Surface Features and 500mb Height Anomalies and Flow
Oakland
North of Oakland morning Morning Morning Kings Run Rd morning
Cranesville
Over the Mt from Sang Run afternoon Afternoon Afternoon Afternoon Afternoon Afternoon Afternoon Afternoon Afternoon Afternoon Nollie on the climb Ditto–Back across the Mt. Icy.
The Yough at Sang Run
–Afternoon
Grantsville to Savage Mt
––––Sideling Hill viewed from Savage Mt eastern Garrett County. This range has the best snow chance Sunday
Rainy a.m, with a switch to snow later in the a.m Wv high ground, then around noon elsewhere.
Bittinger 2NW Valley
precip .56
Year to date 50.60
Snowfall .8
Snowfall month to date 7.5
Snowfall season to date 24.1
Dyacon Data Below
Dyacon outage on the red coloration. Numbers will be corrected at months end Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Bittinger 2NW Valley morning Up from Bittinger 2NW Valley morning Rock Lodge Rd near The Glades morning West of Bittinger afternoon West of Bittinger afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley 5pm boardsweep of .8Bittinger 2NW Valley evening Bittinger 2NW Valley evening Bittinger 2NW Valley evening West of Bittinger evening
Garrett County Airport
Mchenry morning Deep Creek Lake morning Noon Mchenry
Top of Wisp
12:15pm
Canaan Heights/Davis 3SE
7am to 7am data mmts coop bp
Climate Reference Network Canaan
Cabin Mt at Bald Knob
Cabin Mt-Western Sods
Bear Rocks-Dolly Sods
Spruce Knob
Canaan Valley Refuge
Mt.Davis
No data due to mid October bear attack on the station
Snowshoe
Petersburg Grant County Airport
Elkins Airport
Site Comparison
Dy007-Canaan Valley Refuge 3150′, Dy008-Bittinger 2nw Valley 2600′, Dy002-Cabin Mt at Bald Knob 4350′, Dy003-Cabin Mt-Western Sods 4035′, Dy004-Spruce Knob 4820′, Cvpw2-Climate Reference Network Canaan 3380′, KW99-Petersburg Grant County Airport 961, K2G4 Garrett County Airport 2933′, KCBE Cumberland Airport 774′, KEKN Elkins Airport 1985′, KMGW Morgantown Airport 1227′, PMN16-Mt.Davis 3038′, KDCA-Reagan National 15′, G1472 Snowshoe 4500′, F0183 Burkes Garden 3050′, DY025-Bear Rocks 4052′
The Valley vs Cabin Mt
Bittinger 2NW Valley vs Garrett County Airport
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
A rainy start to December 11th, that will eventually turn white as we progress through the morning, in to the early afternoon.
Radar this morning indicative of the changeover that is occuring west
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Temps at 9am. Mild air in place with colder air lurking just west. That will push across through the day
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Weather Service out with Winter Weather Advisories for this brief wintry event
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NWS Snow Maps(expected-high-low)
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Off the HRRR
-precip type
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-Temps
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-Windchills
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-Winds
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Snowfall off the HRRR, EURO, GFS below
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Overall a pretty minor event in the grand scheme. However with falling temps, strong winds, and just a few inches of accumulation will make for slick travel. Be prepared.
Nothing like back in 1992 on this date. When a strong Nor’Easter was moving up the coast dumping feet of snow across the Alleghenies
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Do you remember that event?
Looking ahead. Sunday needs watched. A wintry scenario is a possibility and can’t be written off for just a simple rain event. More on that in the coming days.
After brief a.m sun in spots, rapidly turning cloudy with midday, early afternoon rain..then cloudy and pockets of showers. Mild
Bittinger 2NW Valley
precip .14
Dyacon Data Below
Data in red will be adjusted to correction at months end. That occured due to a dyacon outage –Bittinger 2NW Valley morning Bittinger 2NW Valley morning West of Bittinger morning Rock Lodge Rd near The Glades morning Rock Lodge Rd near The Glades afternoon West of Bittinger afternoon West of Bittinger afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley afternoon Bittinger 2NW Valley evening Bittinger 2NW Valley evening Bittinger 2NW Valley evening Bittinger 2NW Valley evening Bittinger 2NW Valley evening Bittinger 2NW Valley evening Bittinger 2NW Valley evening Bittinger 2NW Valley evening Up from Bittinger 2NW Valley evening
Garrett County Airport
Deep Creek Lake morning Deep Creek Lake-Journeys End midday Meadow Run cove afternoon Deep Creek Lake
Top of Wisp
Canaan Heights/Davis 3SE
7am to 7am data mmts coop bp
Climate Reference Network Canaan
Cabin Mt at Bald Knob
Cabin Mt north facing Whitegrass
Cabin Mt-Western Sods
Bear Rocks-Dolly Sods
Spruce Knob
Canaan Valley Refuge
Mt.Davis
No data due to mid October bear attack on the station
Snowshoe
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Petersburg Grant County Airport
Elkins Airport
Site Comparison
Dy007-Canaan Valley Refuge 3150′, Dy008-Bittinger 2nw Valley 2600′, Dy002-Cabin Mt at Bald Knob 4350′, Dy003-Cabin Mt-Western Sods 4035′, Dy004-Spruce Knob 4820′, Cvpw2-Climate Reference Network Canaan 3380′, KW99-Petersburg Grant County Airport 961, K2G4 Garrett County Airport 2933′, KCBE Cumberland Airport 774′, KEKN Elkins Airport 1985′, KMGW Morgantown Airport 1227′, PMN16-Mt.Davis 3038′, KDCA-Reagan National 15′, G1472 Snowshoe 4500′, F0183 Burkes Garden 3050′, DY025-Bear Rocks 4052′
The Valley vs Cabin Mt
Bittinger 2NW Valley vs Garrett County Airport
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
The cold pattern relaxed, replaced by a milder surge, some rain and soon will briefly flip back cold, with a strong cold push that catches the back edge of the precipitation Wednesday. That changes rain to snow. Accumulations look rather light, enough to cause slick travel though. Wednesday pm will feature strong winds and a rapid freeze up, especially through the overnight.
Out the door this morning, temps are running mainly 30s, 40s. Some clear skies in areas allowing the valleys to drop off. The northern Canaan station down to 29° this morning.
A view from the top of Timberline this morning off their webcam below
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8am Temps 12/10/24 below
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Cloud cover will be pushing back through the area this morning with showers following soon after.
A look at the models-
First the 6z GFS
Rain increasing overnight in to Wednesday
Rain to Snow Wednesday. First across the Wv High Ground and to the Mason Dixon around late morning/ midday give or take.
Rainfall amounts .4 to .8 with localized higher pops
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-Rainfall through changeover
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-Snowfall off the GFS
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– Incoming cold push then a relaxtion
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-Windchills Thursday morning
6z Euro
very similar to the GFS
Rain increasing through the pm hours in to Wednesday a.m
Rain to Snow, First the Wv high ground and a rapid changeover mid to late morning/midday. Sometimes these occurrences happen faster than modeled
rainfall amounts prior to changeover .5 to 1.0
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-Euro rainfall amounts below
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-Snowfall Amounts off the Euro
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– Temps off the Euro, the cold push then a relaxation, but not quite as much as the GFS
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-Winds Wednesday pm(these continue through Thursday)
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NWS SNOWFALL OUTLOOK
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IN SUMMARY ON THE WINTER ASPECT
A general 1-3″ likely with favored locations 2-5″. Upslope behind the system is limited with rapidly incoming dry colder air
Rapid Freeze Up
Strong gusty winds Wednesday-Thursday (advisories may be issued)
Temps in the teens by Thursday morning, Wv high ground upper single digits. Windchills below 0 for many above 2500′ with -10 to -18 windchills across the high exposed Wv tops
Temps modified Friday
With the cold, dry high sitting just NE by Sunday, never rule out wintry potential with that setup. A wedge setup may very well be in play.
Allegheny Mountains Weather 