... High pressure returns for the weekend. Strong storm system to bring rain Sunday night and Monday followed by first measurable snow of the season for most areas Monday night into Tuesday.
NEAR TERM /THROUGH TONIGHT/... As of 315 AM Saturday...
A weak cold front currently pushing eastward through the area is expected to exit by morning. Behind the front, drier air will enter the area with high pressure building in from the west during the day and remaining in control for the remainder of the near term period. Skies will clear from west to east during the day with the lowlands becoming clear during the morning. Over the mountains, however, clouds may linger into the afternoon before clearing. With clear conditions continuing into the night and temperatures lowering toward dewpoints, some late night fog may develop.
High temperatures will be normal today with the lowlands in the mid 40s to low 50s and the mountains in the upper 30s to 40s. Tonight, temperatures are expected to fall into the 20s and 30s.
SHORT TERM /SUNDAY THROUGH TUESDAY/... As of 330 AM Saturday...
Surface high pressure will shift east away from the area during the day Sunday. This will result in a return of SSW low level wind fields and resultant initiation of warm air advection. If WAA kicks in a little faster than currently forecast, then forecast highs for Sun afternoon may be a little warmer than indicated.
Focus then turns to the arrival of a long talked about storm system for Sunday night into Monday. Large-scale synoptic lift is prog to increase Sunday evening with a large rain shield expected to spread NNE overhead by midnight. During the overnight hours a deepening surface low will arrive from the southwest and ride northeast along/just west of the spine of the Appalachians...and exit our area of responsibility by mid morning Monday. Rain, moderate at times, will prevail areawide during the second half of Sunday night through much of Monday morning. Temperatures overnight should cool some in the evening, and then are likely to briefly warm (primarily for West Virginia) overnight as the surface low tracks across. Cold air advection should then initiate by late morning Monday with temps falling during the afternoon.
Steady rain Monday morning should transition more into light rain showers in the afternoon. By Monday evening, synoptic lift is prog to increase again rather significantly as a strong H5 low barrels into the area and nearly saturated moisture depth occurs from the sfc to H5. With a continued cooling thermal profile, increase in moisture depth aloft, and increasing lift in the DGZ, prolonged periods of snow showers are likely to occur Monday night into Tuesday morning. Thus, most areas should see their first measurable snowfall of the season Monday night.
For Monday night: Snowfall amounts across the lowlands should generally be on the lower end...around an inch to maybe two, and primarily on grassy surfaces. For the higher elevations/mountains, generally 2 to 4 inches are currently expected. Beyond sunrise Tuesday, snow showers should generally taper off during the day, ending last across the NE CWA. An additional inch of snow may occur pretty much anywhere Tuesday morning before the snow comes to an end. Of note, when taking a look at the latest available dProg/dt potential snowfall values over the last four guidance cycles, there has been a gradual reduction in expected values...potentially due to guidance trending a little warmer with sfc conditions. However, we're still talking about a system a few days away so forecast snow amounts may still change (to higher or lower values) between now and then. To view maps of our latest snowfall forecast, you can go to weather.gov/rlx/winter
Regardless of how much snow does/does not occur Monday night and Tuesday, confidence IS high that temperatures on Tuesday will likely be the coldest of the week. The cold temps, combined with brisk and gusty winds, along with some snow showers, will make it feel rather miserable outside.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... As of 350 AM Saturday...
By mid week, high pressure tries to build into the region but may struggle to do so. A slow warming trend is currently expected for the second half of the week. Next storm system may arrive late in the forecast period, but a lack of run-to-run guidance consistency and a chaotic late-week synoptic chart means significant changes to future forecast packages are probable.