Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 181348 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 948 AM EDT Tue Oct 18 2016 .SYNOPSIS... High pressure in the western Atlantic will remain in place for the next several days. A cold front will slide southward toward the area Wednesday before lifting back north Thursday. Another, stronger cold front will cross the region Friday. High pressure will return for the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Fog is visible in river valley locations across the region this morning. Will dissapate this morning. Mostly sunny conditions expected today with temperatures rising in the mid to upper 80s. Previous discussion... A large ridge of high pressure, both aloft and at the surface, centered to the south of the region will be in control of the weather today. Once patchy fog lifts early this morning, mostly sunny skies and very warm temperatures will be the theme of the day. Highs will top out in the mid to upper 80s and be on the order of 15-20 degrees above climatological normals. Records at all three major climate sites will be in jeopardy (see climate section below). && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... Another mostly clear night is in store for tonight, along with some patchy fog, similar to previous nights. Temperatures remain very mild again with lows in the low to mid 60s. A weak boundary will then try to push southeastward towards the region Wednesday and Wednesday night before lifting back northward into Thursday. There are still some discrepancies as to the southern extent of its progression, but latest trends indicate that it will likely push southward enough to bring some clouds later Wednesday, Wednesday night, and into Thursday morning, along with the potential for some isolated/scattered rain showers. Very warm temperatures will continue Wednesday with record or near-record warmth. High temperatures will rise into the 80s area-wide again, with lows Wednesday night in the 50s/60s. Abnormally warm weather persists into Thursday, although the temperature forecast is a little trickier and dependent on how quickly the boundary and any remaining clouds lift out. Will show temperatures in the upper 70s in northern Maryland to mid 80s in central Virginia. Potent upper level trough and frontal system then approaches Thursday night with increasing chances for rain showers from west to east. Lows still mild out ahead of the front, in the 50s to low 60s. && .LONG TERM /FRIDAY THROUGH MONDAY/... A potent cold front will pass through the region Friday and an upper-level trough will build overhead behind the boundary for Friday night. Showers are possible with the frontal passage Friday but much cooler and drier air is likely to move in with a northwest flow behind the boundary Friday night. High pressure will build overhead for the weekend...bringing dry and seasonably cool conditions. A reinforcing cold front will pass through Sunday night into Monday and high pressure will return for later Monday. Little moisture will be associated with the boundary so conditions should remain dry. && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... VFR expected area- wide with a few high cirrus as well as a few fair weather cumulus this afternoon. Winds light and variable early this morning become south/southwest 5-10 knots this afternoon. Mainly VFR expected tonight and Wednesday, however there will likely be some patchy fog around again overnight with reductions to MVFR/IFR possible. May be some lower ceilings Wednesday night into Thursday morning with a weak frontal boundary near the area. Rain shower chances then increase Thursday night along with the possibility for some reductions in ceilings/visibilities as a cold front nears the region. A cold front will pass through the terminals Friday. Showers and subvfr conditions are possible. A wind shift to the northwest is expected behind the boundary. VFR conditions are expected for the weekend behind the boundary as high pressure builds toward the area. && .MARINE... Winds will be primarily out of the south and sub-SCA through Thursday. May see a few gusts approach 20 knots later this afternoon, but confidence too low to raise a Small Craft Advisory. Winds increase a bit out of the south Thursday night ahead of an approaching frontal system and winds may approach SCA conditions. A cold front will pass through the waters Friday. Gusty northwest winds are expected behind the front through Saturday night. A small craft advisory will be needed and gale warnings may be needed for portions of the waters during this time. High pressure will build toward the waters Sunday and a reinforcing cold front will pass through Sunday night into Monday. A small craft advisory will likely be needed for the waters during this time. && .TIDES/COASTAL FLOODING... A south to southwest flow will continue over the waters through Wednesday night. Southerly winds are most likely Thursday into Friday ahead of a cold front. Elevated water levels are expected during this time. Minor tidal flooding is possible for sensitive areas...particularly during the high tide cycle during the evening into the overnight hours where that will be the higher of the two. A potent offshore flow will develop behind a cold front later Friday through the weekend. Blowout tides are possible during this time. && .CLIMATE... Below is a list of record daily warm temperatures for October 18th through 20th. Washington-Dulles broke the record high temperature on October 17th. The high was 84 degrees breaking the old record of 83 degrees set in 1963. Record daily high temperatures Site 10/18 10/19 10/20 DCA 85 (1938)* 88 (1938) 86 (1969) BWI 82 (1945)* 82 (1947)* 87 (1969) IAD 82 (2007)* 83 (1991)* 83 (1969) *also occurred in previous years Record daily warm low temperatures Site 10/18 10/19 10/20 DCA 68 (1947)* 65 (1905) 64 (1885)* BWI 69 (1928) 67 (1905) 65 (1910) IAD 60 (1968) 60 (2011) 59 (1993) *also occurred in previous years && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...BJL NEAR TERM...MM/HSK SHORT TERM...MM LONG TERM...BJL AVIATION...BJL/MM/HSK MARINE...BJL/MM TIDES/COASTAL FLOODING...LWX CLIMATE...LWX is the U.S. government's official web portal to all federal, state and local government web resources and services.