Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 231350 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 950 AM EDT Sat Mar 23 2019 .SYNOPSIS... High pressure will build across the area through Sunday. The next low pressure system will pass near the area on Monday, then Canadian high pressure will build in for the middle of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Strong low pressure is moving into the Canadian Maritimes this morning. Tight cyclonic flow remains across the area through, meaning winds are still quite gusty. While there are several inversion between the surface and 500 mb, winds within this layer 40-45 kt. Most of the strongest winds aloft are failing to mix to the surface, but some sporadic gusts up to 40 mph will be possible for a couple more hours (a few stronger gusts may persist on the ridge tops). It will remain breezy into the afternoon given the pressure gradient, though wind speeds should lessen some. The only clouds remaining are across the Appalachian ridges, and even these should dissipate as high pressure builds. High temperatures are expected to range from the mid 40s to mid 50s. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... The surface high will move overhead by tonight. With clear skies, temperatures should drop back into the 20s and 30s. The high will move off the southeast coast on Sunday. Southwesterly flow will help temperatures rebound into the 50s and 60s. Mid and high level clouds will begin to increase during the afternoon. The next shortwave trough and associated surface low will approach from the west and affect the area Sunday night into Monday night. With little interaction between this wave and the northern stream, it looks like the low will take an easterly track nearly over the area. Eventually, the Canadian cold front will overtake it from the north, but likely not until most of the precipitation exits. A few showers will be possible as ascent increases Sunday night, although temperatures should be above freezing everywhere. The best chance of rain will be Monday as the low crosses, although amounts will be light and precipitation may tend to be spotty at times given the system`s continental origins. If current trends for the low track hold, temperatures may ultimately be held in the 40s and 50s for a larger portion of the area (versus 60s). Some wet snow flakes can`t totally be ruled out Monday night as the system pulls away, although am currently thinking the best chance for this to happen would be over the higher elevations. Lows AOB freezing are forecast for much of the area, but this will likely occur well after precipitation ends for most. && .LONG TERM /TUESDAY THROUGH FRIDAY/... After Monday, much of next week will feature quiescent weather dominated by surface high pressure. Temperatures will start cool and below normal but rebound to near or above normal by week`s end. High pressure will build into the northeastern US on Tuesday, move to the coastal plain by Wednesday and offshore on Thursday. This will lead to mostly sunny/clear skies and dry weather through the period. The coolest temperatures are expected to be Tuesday and Tuesday night with highs in the 40s to near 50F and lows in the 20s to around 30F. Temperatures will moderate through Wednesday and Thursday with highs Wednesday rebounding through the 50s, and reaching the upper 50s to low 60s by Thursday. A low pressure system will then be moving through the central US and towards the Great Lakes by Friday. Southerly flow will increase out ahead of this system across the region, but dry weather is expected to continue. Highs should reach well into the 60s Friday. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... The main aviation concern for the TAF period will be continued gusty NW winds. Gusts should generally range from 25-30 kt, but some rogue gusts into the upper 30s could occur through mid- morning. Winds should subside quickly after sunset this evening as high pressure builds in. VFR conditions will persist through Sunday and likely through much of Sunday night, although some light rain showers may arrive ahead of the next system. This low will cross the area on Monday, with rain likely affecting the area and the potential for MVFR conditions. The chance for precipitation will dwindle by Monday night. VFR under building high pressure Tuesday and Wednesday. && .MARINE... Strong, gusty winds continue on the waters this morning. Have replaced the Gale Warning with a solid Small Craft Advisory for much of the waters. Between Drum Point-Smith Point, including Tangier Sound and the mouth of the Potomac, the Gale Warning set to expire at 10 am anyways. Small Craft Advisory conditions will continue for the rest of the day. Observations generally support that plan, although there still are some borderline gale gusts. Winds within the mixed layer do gradually decline. Wind should subside tonight as high pressure builds in, but it may not be until an hour or two after sunset. Have adjusted the end time of the Small Craft Advisory later for the bay between Drum Point- Smith Point, including Tangier Sound and the mouth of the Potomac. May need to delay the ending of the SCA elsewhere too. Will make that decision later today. Southwest winds around 10-15 kt develop Sunday and Sunday night as the high moves offshore. Low pressure will cross over the waters on Monday. Given the current track, winds may remain below criteria for most of the day. A strong cold front will push south during the afternoon and evening, with northerly winds likely resulting in Small Craft Advisory conditions in its wake. SCA conditions possible Tuesday following frontal passage, with winds lessening by Tuesday night and Wednesday as high pressure builds in. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ530>533-535-536-538>542. Small Craft Advisory until 11 PM EDT this evening for ANZ534- 537-543. Gale Warning until 10 AM EDT this morning for ANZ534-537-543. && $$ SYNOPSIS...ADS NEAR TERM...ADS/HTS SHORT TERM...ADS LONG TERM...MM AVIATION...ADS/MM MARINE...ADS/MM/HTS is the U.S. government's official web portal to all federal, state and local government web resources and services.