Area Forecast Discussion
Issued by NWS Sterling, VA

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988 FXUS61 KLWX 020801 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 301 AM EST Fri Dec 2 2016 .SYNOPSIS... High pressure will gradually move into the region through Sunday. An upper-level disturbance will pass through the area Sunday night and high pressure will briefly return for Monday. Coastal low pressure may impact the area Tuesday into Tuesday night before high pressure briefly returns for Wednesday. A potent cold front will move through late next week. && .NEAR TERM /THROUGH TODAY/... West-northwest flow will continue through today and actually become re-enforced late today and tonight as a system moves through New England this afternoon, sending another push of modest cold-air advection southeastward. Seeing plenty of cloud cover early this morning from about the DC metro on north and west. Thinking is that this will erode as the morning hours progress, before additional strato-cumulus clouds develop by the afternoon in the west/northwest flow. Overall theme should be mostly cloudy north/west, mostly sunny south/east with a breeze up to about 20-25 mph. Some upslope snow showers continue to be possible along the Allegheny Front as well. Temperatures will be right around climatological normals, with highs in the 40s/50s. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... As mentioned, northwest flow/CAA gets somewhat re-enforced tonight, so overall idea of partly/mostly cloudy north/west and mostly clear south/east is expected to continue. Otherwise, near normal temperatures with lows in the upper 20s to mid 30s. High pressure over the midwestern US will slowly move eastward and towards the region on Saturday, however the gradient between it and the gradually departing system over southeast Canada will still keep the area in a brisk northwest flow with gusts 20-25 mph. Again under northwest flow, theme of cloudier northwest and clearer southeast should continue. High temperatures will be a couple of degrees cooler than today, generally in the 40s to around 50F. High pressure will briefly be in control Saturday night into Sunday morning leading to a slackening wind field and continued dry weather. However, a weakening system coming out of the mid- Mississippi Valley will lead to increasing clouds on Sunday, followed by increasing chances for some light overrunning warm air advection precip by late Sunday and Sunday night. Still several days out, but the potential for some light frozen precipitation exists, especially in northern/western and higher elevation locations. Thermal profiles look to favor mostly rain from the I-95 corridor southeast. Highs Sunday will be in the 40s for most, with lows Sunday night in the 30s. && .LONG TERM /MONDAY THROUGH THURSDAY/... High pressure will briefly build overhead Monday from the Midwest...likely bringing dry and seasonably chilly conditions. Low pressure in the southern branch of the jet will track through the southern Plains Monday before moving northeast toward the Tennessee Valley Monday night. As the low moves into the Tennessee Valley Monday night...clouds will lower and thicken and precipitation will begin to overspread the area from southwest to northeast. The low will slowly pass by to our west Tuesday while it transfers energy to a coastal low. Warm and moist air from the Gulf of Mexico and Atlantic Ocean will overrun the surface cooler air in place...likely resulting in a soaking rain for most areas. However...there are some concerns with precipitation type. As the low approaches Monday night into Tuesday...this will cause an upper-level ridge to build over New England. That will allow for the surface high to our north to strengthen. There will not be much in the way of cold air...but there will be plenty of dry air ahead of the storm. Insitu cold air damming may result in enough cold air late Monday night into Tuesday for snow to occur. The best chance for snow will be across the ridges. This will have to be monitored since uncertainty remains high this far out. Any snow should change over to rain Tuesday night as warmer air takes over with the primary low passing by to our west. The primary low will track into Canada Tuesday night while the coastal low slowly moves off to the east. Rain will decrease in coverage...but low clouds and fog will likely hang around. Weak high pressure will settle overhead for Wednesday before a potent cold approaches late in the week. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... Predominantly VFR conditions expected through at least Sunday night. Scattered-broken stratocumulus deck at 4000-6000 feet will continue with varying coverage into Saturday. This will eventually be replaced by an increasing high cirrus deck by Sunday morning. Clouds will lower and thicken Sunday night as a weakening system moves through, along with the chance for some rain/snow showers. A brief period of sub-VFR is possible. Winds will be out of the west/northwest through Saturday, with daytime gusts up to 20-25 knots. VFR conditions are likely for Monday through Monday evening. Clouds will increase and rain will overspread the areas late Monday night into Tuesday. IFR conditions are likely for Tuesday through Tuesday night. && .MARINE... Small Craft Advisory is in effect for all waters today through Saturday for persistent gusty northwest flow with gusts in excess of 20 knots. The period of strongest winds is expected tonight into Saturday morning when winds may approach gale force for a time. Winds begin to decrease Saturday night, but SCA may need to be extended with gusts up to 20 knots still possible. Winds finally drop below SCA criteria Sunday. High pressure will remain over the waters Monday into Monday night. Coastal low pressure will develop late Monday night into Tuesday near the Carolinas. The low will slowly track up the coast Tuesday afternoon before moving off to our east Tuesday night. A Small Craft Advisory will likely be needed for the waters Tuesday through Tuesday night. High pressure may briefly build toward the waters for Wednesday. && .CLIMATE... Meteorological autumn 2016 has ended (it runs from September 1st through November 30th). It was unusually warm and dry across the much of the area. Below are preliminary temperature and precipitation rankings for this autumn. Washington DC area (Ronald Reagan National Airport, DCA) Temperature (warmest) Precipitation (driest) 1. 63.9 degrees (2016) 1. 1.83 inches (1930) 2. 63.3 degrees (2007) 2. 2.42 inches (1941) 3. 2.65 inches (2001) 4. 3.33 inches (1998) 5. 3.45 inches (1879) 6. 4.07 inches (1967) 7. 4.16 inches (2016) 8. 4.26 inches (1973) Records have been kept at DCA since August 1st 1941. Additional temperature records in the Washington DC area date back to 1872, and additional precipitation records date back to 1871. Baltimore MD area (Baltimore-Washington International Thurgood Marshall Airport, BWI) Temperature (warmest) Precipitation (driest) 1. 64.7 degrees (1931) Not in Top 20 (2016 was 29th driest 2. 63.4 degrees (1941) with 6.65 inches) 3. 63.3 degrees (1881) 4. 61.9 degrees (1946) 5. 61.8 degrees (1900) 6. 61.3 degrees (1970) 7. 61.1 degrees (1927) 8. 60.7 degrees (1947)* 9. 60.4 degrees (1930) 10. 60.3 degrees (1919) 60.3 degrees (1945) 60.3 degrees (1942) 13. 60.2 degrees (2016) 60.2 degrees (1985) *One day of missing data Records have been kept at BWI since January 1st 1950. Additional temperature records in the Baltimore MD area date back to 1872, and additional precipitation records date back to 1871. Dulles VA area (Washington Dulles International Airport, IAD) Temperature (warmest) Precipitation (driest) 1. 60.3 degrees (2007) 1. 3.96 inches (1998) 2. 60.0 degrees (2016) 2. 4.59 inches (1978) 3. 59.5 degrees (1985) 3. 4.61 inches (1965) 4. 4.97 inches (2016) 5. 5.31 inches (1981) Records have been kept at IAD since November 30th 1962. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ530>534-536>543. Small Craft Advisory from 7 AM this morning to 6 PM EST this evening for ANZ535. && $$ SYNOPSIS...BJL NEAR TERM...MM SHORT TERM...MM LONG TERM...BJL AVIATION...BJL/MM MARINE...BJL/MM CLIMATE...DFH

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