So. Much. Wintry. weather. Here is LWX’s take.
High pressure will remain situated off to the north to northwest of our region on Wednesday as a warm front builds near our region. Dry conditions ahead of the warm front building into our region will be dry with light and northerly winds. The warm front is expected to start impacting our region late Wednesday afternoon as overrunning precipitation combines with reinforcing cold air from the north to start the long duration winter event. Precipitation is forecast to impact our region after 18Z Wednesday with main winter impacts beginning after 00Z Thursday. A brief warm up ahead of the precip is expected up into the low 40s on Wednesday but then the high pressure to the north is expected to wedge in cold near to below freezing temps south through the majority of our region.When the winter precipitation begins, some areas in central Virginia will likely experience periods of rain/snow/sleet mix especially down near Charlottesville during the 21Z to 6Z period. Cold air is then expected to filter in for all of our region by Thursday morning leading to a transition to an all snow event. Two rounds of wintry precipitation are likely with this long duration with the first round coming with the overruning precipitation from the warm front located near our region which will mainly be through 15Z Thursday. Mixing of snow and sleet will likely prevent higher snow totals through the first round of precipitation but areas along our Allegheny front zones in western MD, eastern WV and Highland VA could see local amounts upwards of 8 inches. I don`t really have confidence to go further east with higher snow totals for the majority of our region reaching Advisory level snow at the most for the first event. A second round of wintry precipitation is expected as the surface low moves off to our south Thursday afternoon into Friday. This second round will likely be the heaviest snow of the event as cold air will be entrenched throughout the thermal layer and some of the heaviest precipitation is expected to move through our region during this period. Generally the second round of snow is expected to be focused more south of the DC metro and I-66 corridor with the highest totals expected down into central Virginia at this time. There has been a general trend southward with guidance which leads to keep the heaviest snow further south in central Virginia. Some localized enhancing of snow totals further north will be possible due to a low level jet forming Thursday evening and i`m not confident enough to rule out heavier snow reaching further north at this time with the second round. Generally through the full long duration event which is expected to be almost a 48 hour period, the majority our region may see 5 to 8 inches with locally higher amounts possible in central Virginia and along the Allegheny front. After 00Z Wednesday, temperatures at the surface are expected to remain mostly below freeing throughout the event.
LONG TERM /FRIDAY THROUGH TUESDAY/... On Friday morning, a trailing shortwave will traverse the stalled frontal zone set up to the south. The band of overrunning snowfall should continue through much of the morning before high pressure builds in for the second half of the day. This may produce another 1 to 3 inches of snow on top of what will have fallen in the previous 36 hours. Mostly cloudy conditions should prevail in the wake which will keep temperatures at, or below the freezing mark in spots aside from central Virginia and southern Maryland. Abundant cloud cover sticks around overnight with low temperatures in the low/mid 20s, teens in the mountains. A rather potent upper low originating from the polar regions is forecast to drop southward from Manitoba and move across the Great Lakes over the weekend. Within the southern stream, another impulse begins to move through the southeastern U.S. and eventually offshore of the Mid-Atlantic coast. A coastal wave forms with these height falls on Saturday which may introduce additional snowfall to the region. The best chance for accumulations will be west of I-95 given more supportive boundary layer temperatures. Given uncertainty in the timing and position of this system, the rain/snow line will need to be ironed out in future model cycles. Precipitation may linger into Sunday as an Arctic cold front races toward the Eastern Seaboard. It is difficult to say how much snowfall would occur along this advancing boundary with the 12Z GFS being the most robust. The modified Arctic air arrives in earnest by Sunday evening and into the overnight hours. Sunday night`s low temperatures likely drop into the teens east of the Blue Ridge and Catoctin Mountains with single digits possible elsewhere. For early next week, tranquil conditions are expected for Monday in the wake of the weekend system. A sprawling 1048-mb ridge centered over the Middle Mississippi Valley will extend modified Arctic air into the central/eastern U.S. Monday`s high temperatures should stay at, or below the freezing mark in most locations with teens over the higher mountain peaks. Yet another system is continuing to be monitored with arrival early next Tuesday. Quite a bit of spread exists in the guidance but it continues to bear watching.
