Mailman

.NEAR TERM /THROUGH FRIDAY/... The leading edge of shallow cold air at 2200UTC is straddling the forecast area, stretched from near Marienville PA to near Pittsburgh to near Fairmont WV. Atop this shallow layer remains a relatively warm tongue of air, leading to a PTYPE transition across wrn PA/ern OH and the nrn WV panhandle. Farther west near ZZV, cold air has successfully eroded the warm tongue, leading to a region of all snow from near PHD to ZZV. Prior forecast (see below) identified a focused region of ern OH where conditions will be favorable for considerable snowfall rates this evening as still colder air invades and lift/saturation are maximized through the dendritic growth zone. This region still seems to be where the highest totals are likely. Headlines were continued, but upgraded for a few counties adjacent to the ongoing warning in line with the latest information available. The latest expectation is that snow rates in ern OH could potentially reach 1-2" per hour for a window this evening. By 0600UTC, a dry slot will erode moisture aloft, which should bring an end to widespread threat of heavy snow. This dry slot brings some concern about snow amounts for wrn PA, where a late transition to snow (as most models suggest) may preclude totals quite as high as previously forecasted. Dry, fluffy snow likely will continue past 0600UTC, but fall rates will be limited. The ridges, however, will remain at a temperature favorable for highly efficient snow ratios, and still could see notable totals by mid-day tomorrow.

DT claims 6" for all.

18z GFS was rather active.

Lake effect snow making its way into western PA. Will be nice to see.

Yeah.. all the models seem to be hinting (however you wanna call it 8 days out) at the possibility of some holiday flakes. Would be nice. I need a couple days off from the models, though. It's a grind that can wear you down.

.NEAR TERM /THROUGH THURSDAY/... Precipitation is beginning to wind down across the Upper Ohio Valley and Allegheny Mountains. Heavy snowfall has fallen across much of the area, leading to hazardous travel conditions. Winter weather advisories and warnings remain in effect through dawn. 3 to 6 inches fell across much of eastern Ohio into the Northern West Virginia panhandle, while the Pittsburgh metro received in between 6 and 12. The local "bullseye" as far as snow accumulation is east towards Indiana County, with multiple reports over a foot. Please see the latest local storm reports (LSRs) and Public Information Statement (PNS) to see the latest snow reports. Precipitation has backed off significantly, or has come to an end altogether, for areas west of the northern WV Panhandle. Meanwhile, high snow rates in excess of an inch are still possible east of I-79 where the exiting TROWAL/Fgen band shifts off to the north and east. The I-79 corridor, Pittsburgh included, is looking at a possible inch of additional accumulation while locations farther east from Clarion southward through Indiana and Greensburg may easily pick up an additional 3 or more inches of snowfall before the higher rates end in the next few hours. By daybreak, dry air will begin to move into the dendritic growth zone such that any remaining dendrites will turn into an area of freezing drizzle. However, low-level moisture may also be lost, coincident with widespread meso- and synoptic- scale lift also ending. So most precipitation should be out of there area by dawn or shortly thereafter. A few models pick up on a fetch of lake-enhanced moisture with low-level instability sufficient enough to produce a few flakes in the mid-afternoon... however, accumulation will nil and any impacts insignificant. As far as temperature, lowered the immediate forecast down a few degrees based on observations. Temps will be slow to come up tomorrow given the cold air mass, cloud cover, and snowpack. Highs will range from around 30-35 for most of the area and few degrees colder in the higher elevations of the Allegheny Mountains.

Still snowing. I measured 8".

Maybe close the calendar year out with a white Christmas.

Nice to see the dry slot off to the east.

Special Weather Statement National Weather Service Pittsburgh PA 541 PM EST Wed Dec 16 2020 PAZ007-008-014>016-021>023-029-031-073>076-170045- Armstrong-Clarion-Fayette Ridges-Mercer-Greene-Westmoreland-Washington-Allegheny-Indiana- Jefferson-Butler-Venango-Westmoreland Ridges-Fayette- 541 PM EST Wed Dec 16 2020 ...AN AREA OF HEAVY SNOW WILL AFFECT EAST CENTRAL MERCER... SOUTHWESTERN VENANGO...SOUTHEASTERN WASHINGTON...BUTLER...INDIANA... ALLEGHENY...JEFFERSON...WESTMORELAND...NORTHEASTERN GREENE... ARMSTRONG...SOUTHERN CLARION AND FAYETTE COUNTIES... At 539 PM EST, an area of heavy snow was located along a line extending from 8 miles east of Slippery Rock to Monongahela. Movement was northeast at 35 mph. Snow is accumulating rapidly within this band of heavy snow, at 1-2 inches per hour. Use caution when traveling, especially on interstates. A Winter Storm Warning remains in effect until 7 AM Thursday. Locations impacted include... Pittsburgh... Penn Hills... Mount Lebanon... Bethel Park... Ross Township... McCandless Township... Monroeville... McMurray... Greensburg... McKeesport... Indiana... Butler...

Big time radar return just east of 79 in southern Washington County.

.NEAR TERM /THROUGH THURSDAY/... The eve update generally involved some cosmetic adjustments as widespread snow continues in response to an encroaching upper trough which features an impressive coupled jet structure. The resulting divergence is generating a strengthening frontogenetically forced snow band which will cross the I 79 corridor during the rush hour. Otherwise expect variable snow intensity and flake size until mid level dry slot encroachment in the predawn of Thursday. That process with declining omega values/ascent parameters will signal the end of accumulating snow potential. Patchy freezing drizzle will linger, but ice accumlation greater than a trace is not anticipated in that time frame. No changes were made to warning and advisory headlines.

4"-ish here, as well.

Just about 2" here.

Rain in Morgantown.

Coming down good here. Already a little over 1".

PBZ warning coordinator said last night on their Facebook live that he expects areas north of the Mason-Dixon to stay all snow. I sure hope so.

.NEAR TERM /THROUGH THURSDAY/... As of 14Z across the area, thE column is saturating as snow begins to reach the ground in many locations with some accumulations being reported in southwest OH counties and WV counties. Latest model trends continue to set up with the highest snowfall rates setting up across southwest PA and the WV mountains by 21Z and persisting int the overnight hours where some 1 inch per hour and possible higher snowfall rates continuing into the overnight hours. Additionally, trends seem to suggest the column remaining saturated enough through 12Z before losing the bulk of the moisture depth in the4 atmosphere, especially in the WV counties. Thus after 12Z, we should begin to see some freezing drizzle set up for a few hours before this transitions over to all drizzle and rain. Temperatures then will warm to just about freezing.

Things are turning a shade of white.