555 FXUS61 KLWX 101932 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 232 PM EST Thu Dec 10 2020 .SYNOPSIS... High pressure will remain in control of the region through early Saturday. A cold front will cross the region on Sunday resulting in a renewed chance for showers. Another low will likely pass south of the area on Monday. High pressure will briefly build over our region Tuesday before another low pressure system potentially affects our region Wednesday. && .NEAR TERM /THROUGH TONIGHT/... High pressure overhead is resulting in clear skies and relatively light winds throughout the remainder of the afternoon. As the high shifts offshore, winds are expected to become more southerly by late this afternoon/evening. Increased BL moisture overnight can be expected as a result of a more southerly flow. Therefore, patchy fog is possible overnight. With overnight temperatures dropping down to near freezing, there is the possibility of isolated instances of freezing fog, which could cause some slick spots on roadways for the morning commute Friday. Any isolated instances of freezing fog would be confined to the rural areas, away from the metros. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... Upper-level ridge axis will crest over the CWA Friday resulting in high pressure persisting offshore. As a result, dry conditions are expected to continue tomorrow, aside from any areas of patchy fog that will burn off by mid morning. There will also be a slight increase in clouds as a result from increased moisture from a continued southerly flow. Temperatures will be slightly warmer than today with daytime highs in the mid to upper 50s. A similar temperature pattern can be expected for Saturday. The aforementioned ridge will begin to break down overnight Friday into Saturday as high pressure slips further offshore. Guidance hints on the idea of an increased moisture flux, mainly along and east of I-95 Saturday morning, where fog and patchy drizzle are possible. Simultaneously, low pressure will emerge out of the Tennessee Valley, tracking northeastward into the Great Lakes region through the weekend. The associated cold front will slowly approach the CWA from the west. Therefore, while it is expected to remain mostly dry, spotty periods of showers and/or drizzle are possible throughout the day Saturday. The cold front will cross the region Sunday morning, where a higher chance for shower activity arises. PoPs will remain highest mainly along and west of the Blue Ridge where lift will be the best. Regardless, the front lacks any significant moisture. Therefore, don't expect much in terms of QPF amounts, as guidance keeps QPF amounts around 0.05 inch. && .LONG TERM /SUNDAY THROUGH THURSDAY/... A very active pattern is shaping up for the long term forecast period across the region, with a couple of low pressure systems possibly impacting the area early next week. Sunday looks to be quiet to start, with only perhaps a few lingering showers as a mostly dry cold front pushes through. High temperatures Sunday expected to reach the low 60s though, so quite warm for early December, owing to southerly flow ahead of the front. Gusty winds can be expected over the mountains in the wake of this front, but not looking like we will reach any advisory thresholds. By Sunday night into Monday, things begin to look a little more interesting, as low pressure slides by south of the region. At this point, most precipitation is expected to stay to our south, with only light precipitation reaching into central VA and perhaps southern MD - there is a substantial amount of spread in ensembles, though. Temperatures may be marginally supportive of some wintry precipitation as well, particularly across western portions of the forecast area (over the higher elevations). Model guidance has been fairly consistent keeping this system far enough south to not be much of an issue in terms of heavy precipitation, and keeps most areas east of the Blue Ridge out of an wintry threat, owing to warmer temperatures. The GFS continues to indicate a northwestward shift with the track of the system; if this trend were to continue, it could bring in higher precipitation totals into the area, which could mean some more snow out west. Highs Monday will be back closer to normal, with highs in the mid to upper 40s east of the mountains. High pressure is forecast to move in behind this system for Tuesday, with dry conditions expected and temperatures slightly cooler than Monday (highs only into the mid 40s). Meanwhile, models are coming into agreement on a strong trough digging into the central CONUS, with a surface low developing over the middle MS River Valley. For Wednesday, we definitely have something to watch in terms of wintry weather. The aforementioned surface low drifts into the Ohio Valley, and transfers energy off the east coast of NC/VA (Miller B setup). Every piece of available guidance shows something resembling this around mid-week. This, paired with high pressure to the north that will act to lock marginally cold air into the region, could lead to some wintry weather. Right now, it is looking like the threat will be relegated to areas west of the I-95 corridor, but many details still need to be ironed out, as this is currently at the end of our forecast period. For I-95 and areas east, we could be looking at a moderate to heavy rain event. For now, we are just mentioning the possibility, as there is a lot of time between now and then. We've highlighted the Day 7 period on the Day 3-7 Winter Threat Matrix. Monitor weather.gov/lwx/winter for the latest. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... High pressure overhead will result in continued VFR conditions today. Light and variable winds will continue to become southerly into this evening as the high shifts offshore. Patchy fog is possible overnight as a result of increased moisture, which could lead to a few hours of sub-VFR conditions through early Friday morning. However, any fog is expected to burn off by mid morning, and VFR conditions are expected to continue throughout the day. While conditions are expected to remain mostly VFR through the weekend, periods of sub-VFR conditions are possible with instances of fog and isolated showers/patchy drizzle Saturday. VFR conditions likely on Sunday, with only a few lingering showers as a mostly dry cold front pushes through the region. For Sunday night through Monday, an area of low pressure will pass by to the south, which could bring rain/low CIGs to portions of the area. For now, CHO stands the best chance to see any flight restrictions from this system. && .MARINE... High pressure moving offshore may result in southerly wind gusts of 15 to near 20 kt later tonight into Friday, but there was not enough confidence to issue a Small Craft Advisory just yet given the marginal gradient and near surface stable layer. Sub-SCA conditions are then likely through Saturday with high pressure offshore inducing a southerly flow. A cold front will cross over the waters on Sunday. Winds will shift to the northwest, and Small Craft Advisories will be possible, if not likely, through Monday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...MSS NEAR TERM...MSS SHORT TERM...MSS LONG TERM...CJL AVIATION...MSS/CJL MARINE...MSS/CJL