Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 241441 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 941 AM EST Fri Feb 24 2017 .SYNOPSIS... High pressure will remain centered off the Mid-Atlantic coast today. A cold front will cross the area Saturday. High pressure then builds over the area Sunday through early next week. A warm front will then lift north into the area Tuesday followed by another cold front on Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Very warm day in store today with the area ensconced in the warm sector of a low pressure system passing through the Great Lakes. Warm southerly flow expected through the day with mostly sunny skies and only scattered cumulus and some areas of high cirrus. 925/850mb temperatures are very similar to yesterday, so expecting highs roughly the same as what was observed yesterday, perhaps a degree or two warmer. This should put highs in the 70s to near 80F, challenging the daily records, and possibly even the all-time February record at Washington/Dulles (see climate section below). && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... A very mild night is in store with low temperatures (50s) likely warmer than normal highs in most locations. A southerly wind likely remains established for most locations, which will limit fog potential. However, there are some indications low stratus could develop. If so, their rate of dissipation Saturday could affect high temperatures and destabilization. A strong cold front will cross from west to east on Saturday. A weakened line of convection is likely to cross into the mountains during the morning hours, reaching the Blue Ridge around midday or early afternoon. What remains of the line may be reinvigorated east of the mountains as it encounters a potentially warmer and more unstable airmass, contingent on the aforementioned clouds. Even so, dew points are expected to remain under 60, with CAPE values likely less than 1000 J/kg. Mid-level winds will be strong though, and SHERB parameter backs up the potential for a high-shear/low-CAPE environment. Marginal Risk remains justified, with strong to locally damaging wind gusts being the main threat. The line should exit southern MD between 5 and 8 PM. QPF less than a third of an inch for most...and possibly much less if the line is thin/broken. Temperatures likely spike into the 70s ahead of the front, with falling temperatures behind it. Besides the gusty shower/storm threat, a pressure surge may follow a few hours behind the front, resulting in wind gusts of 30-40 mph during the early evening. These winds will bring in colder air, with lows falling into the 20s and 30s. Upslope snow showers will be possible, especially during the evening, with amounts less than an inch. High pressure will build from the west Sunday, allowing winds to gradually relax. Temperatures will be much cooler, but closer to normal in the 40s and 50s. The high will begin to move offshore Sunday night, with lows dropping into the 30s. Sub- freezing readings are possible if a location decouples and thicker cloud cover holds off. && .LONG TERM /MONDAY THROUGH THURSDAY/... Models have backed off on precipitation returning to the region on Monday. The front which had been expected to move in from the northwest on Monday now looks to completely dissipate before reaching the area, so POPS have been cut back and temperatures should not drop at all. Instead, developing low pressure to the west in the Plains will push a warm front northward across the area on Tuesday and Wednesday, bringing temperatures back above normal but bringing the return of showers. By Wednesday night, the low will pass to our north in southern Canada, sending a cold front across our region. There might be some thunder with it but right now indications are minimal in this regard. Cooler more seasonable weather will return Thursday as we dry out with high pressure returning briefly. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... The region will remain in the warm sector of a low pressure system passing to the northwest today and tonight. No aviation weather concerns expected through the day today with only some high cirrus and scattered cumulus. Otherwise, southerly winds with some gusts to 20 kt possible. Clouds will increase tonight. Guidance indicates IFR potential, especially east of the Blue Ridge, but will not be biting on that quite yet, preferring a trend to MVFR. Strong cold front will cross the area on Saturday, likely reaching the metros during the afternoon. Thin line of gusty showers/embedded thunderstorms likely (brief IFR possible) , followed by a several hour period of potential 30+ kt westerly gusts. Winds will subside through Sunday morning as high pressure builds in from the west. No aviation concerns Monday. Sub-VFR possible Tuesday and Wednesday with showers. && .MARINE... Southerly flow 10-15 kt today and tonight with high pressure offshore and low pressure moving toward Great Lakes. Am thinking warm air over cold water will minimize potential for higher gusts. Fog will be possible mainly around the northern Bay this morning. Have raised a Small Craft Advisory starting at 10 AM Saturday, although how quickly mixing commences is in question as low clouds may be present. A cold front will bring dramatic change in conditions during the late afternoon to early evening. Line of gusty showers/possible storms will mark sharp wind shift to west. Pressure surge will lag behind the front, so at this time, thinking gradient gale conditions may occur more during the evening hours. However, SMWs will be likely with the line of showers. Winds slowly taper through Saturday night and Sunday morning, although SCA likely continues a good portion of Sunday. There should be a lull Sunday night with high pressure moving across the area. Warm front looks to lift north across the region Tuesday followed by a cold front Wednesday. These features could result in at least small craft conditions. && .CLIMATE... Temperatures today are expected to be at least the second warmest Feb 24th on record (if not break or tie the record from Feb 24, 1985). High minimum records are possible for Friday and less likely for Saturday due to evening temperatures dropping behind an afternoon cold front. Record highs are less likely overall on Saturday as showers and clouds should limit how warm it gets, while DC/Baltimore both set their all-time February highs on that date back in 1930, making them hard to reach. Record high maximum temperatures for February 24 and 25: BWI 79F (1985), 83F (1930) DCA 78F (1985), 84F (1930) IAD 79F (1985), 79F (2000) Record high minimum temperatures for February 24 and 25: BWI 55F (1985), 52F (1930) DCA 52F (1975), 54F (1891) IAD 53F (1985), 47F (2000) Warmest temperatures ever observed in February BWI 83F (2/25/1930) DCA 84F (2/25/1930) IAD 79F (2/25/2000, 2/24/1985) Warmest Februaries (average temperature) DCA BWI IAD 1. 46.9 (1976) 44.0 (1976) 42.1 (1990) 2. 45.2 (1990) 43.9 (1949) 41.1 (1976) 3. 44.7 (1997) 43.3 (1890) 41.0 (1998) 4. 44.3 (2012) 42.7 (1932) 40.9 (2012) 5. 43.9 (1949) 42.6 (1909) 40.5 (1997) Feb 2017 (through the 23rd) DCA: 46.3 BWI: 43.0 IAD: 43.6 Warmest Winters (Dec 1-Feb 28/29) DCA BWI IAD 1. 44.7 (1931-32) 45.3 (1931-32) 40.0 (2011-12) 2. 44.3 (1889-90) 44.4 (1889-90) 39.7 (2001-02) 3. 43.3 (2011-12) 42.4 (1948-49) 39.4 (1997-98) 4. 43.2 (2001-02) 41.9 (1949-50) 39.0 (2015-16) 5. 42.8 (1949-50) 41.3 (1879-80) 38.3 (1990-91) Winter 2016-17 (through Feb 23) DCA: 43.4 BWI: 40.1 IAD: 40.4 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 10 AM to 6 PM EST Saturday for ANZ530>543. && $$ SYNOPSIS...RCM NEAR TERM...ADS/MM SHORT TERM...ADS LONG TERM...RCM AVIATION...ADS/MM/RCM MARINE...ADS/MM/RCM CLIMATE...BAJ/DFH/RCM

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