... Evening mountain snow. Dry and cold for Wednesday and Thursday. Next system approaches Friday.
NEAR TERM /THROUGH WEDNESDAY/... As of 608 PM Tuesday...
Primary mid level frontogenesis is becoming more confined to the mountains where a couple inches of snow may yet occur this evening (primarily on grassy surfaces). Another band of light snow may try to move out of E KY and across central WV early/mid evening. However, snow amounts from this secondary band should be minimal to nil as drier air is quickly moving into the area.
As of 150 PM Tuesday...
We are seeing a change over to light snow or flurries across the western Lowlands, and a switch to snowflakes will continue to expand eastward across the Lowlands and drop in elevation in the mountains (Currently snow at Snowshoe).
It continues to look unfavorable for snow accumulations late this afternoon and this evening outside of the mountains. Upper level jet dynamics will be in place with a strengthening H3 jet across the eastern Lakes amid increasing frontogenesis across the region in the H7-6 layer later this afternoon. The conundrum is the delay in surface cooling and more importantly dry air in the low levels trying to advect in from the west. This has been having an effect across the TN Valley into central KY with low level dry air winning out with precipitation not being reported at ground level despite decent radar returns. This will serves as the battleground late this afternoon and evening as surface temperatures become favorable in the Lowlands. The thinking is areas west of US-119/I-79 corridor look to see mainly festive flakes, with perhaps a rooftop dusting along and just east of the corridor on the hills. The best chance for minor accumulations will be across the mountains which should stiff arm any low level dry air for a time for 1 to 3 inches of snowfall.
Everything pulls east overnight with clearing and tumbling temperatures in its wake. Depending on how much wind can rid the roads of moisture this evening, we make be looking at patchy black ice developing tonight, primarily in rural sheltered locations. Temperatures will bottom out in the lower 20s in the Lowlands and teens to single digits in the mountains depending on elevation.
Sunshine will the the rule Wednesday though quite chilly with afternoon temperatures averaging a good 10 degrees below normal.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 246 PM Tuesday...
Surface high pressure will drift across the region Wednesday night and shift quickly towards the northeast US by late Thursday. This feature will promote dry conditions across the area Thursday with highs in the mid/low 40s, just a few degrees below normal for this time of the year.
Cloud cover will be on the increase Thursday night ahead of mid level shortwave energy that will move across the southern US. This will lead to cyclogenesis in the northern Gulf Coast region, and eventually a coastal low will lift northward along the southeast coast on Friday. This will contribute to precipitation chances increasing across our area from south to north throughout the day. As precipitation initially arrives Friday morning, the aforementioned surface high in the northeast US will wedge down along the eastern slopes of the mountains, providing a shallow layer of sub-freezing air at the surface as WAA increases aloft. Thus, thermal profiles could be favorable for a period of freezing rain Friday morning, particularly across southeastern areas of the CWA. In addition, snow/sleet is possible at the onset of precipitation in the mountains Friday morning. However, by Friday afternoon, low-level cold air will scour out and precipitation will transition to rain across the region.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 246 PM Tuesday...
By Friday night, the aforementioned coastal system will pass east of the area and continue to move towards southern New England by Saturday afternoon, strengthening as it does so. Due to a combination of additional shortwave energy moving across the Great Lakes and moisture wrapping around the coastal system, additional precipitation will continue into Saturday with rain expected area-wide during the day. Precipitation is then expected to transition to snow Saturday night into Sunday as surface temperatures cool. As the coastal system continues to lift to the NNE into eastern Canada, the flow aloft across our area becomes more favorable for a period of upslope precipitation Sunday afternoon. Drier air is then expected to bring an end to any upslope precipitation by Sunday evening.
Any break in precipitation activity across the area is expected to be short-lived as models indicate that a low pressure system will develop near the lower Mississippi Valley on Monday. This system is expected to bring another round of rain and/or snow across the area Monday into Tuesday, but models disagree on the track/timing of the system for now. Thus, have stuck with central guidance on PoPs for now until better model agreement occurs.