Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 240056 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 856 PM EDT Sat Jul 23 2016 .SYNOPSIS... A weak cold front will dissipate as it drops south into the area tonight. High pressure will be in control of the area`s weather Sunday before another front enters the area Monday into Tuesday. This front may stall across the region during the middle of next week. && .NEAR TERM /THROUGH SUNDAY/... No high temperature records were broken (or tied) Saturday. Close though at IAD. Temperatures remain in the lower 90s over much of the forecast area with heat indices around 100. Where storms are able to develop there is a large amount of CAPE available. Any storms which form should exit the SE corner of the CWA near or shortly after midnight. Lows will range from the upper 60s west to 80 in the cities and along the Bay. Ridging will build into the area on Sunday, which should help suppress most thunderstorm development, although an isolated storm will be possible in the higher terrain. Temperatures will probably be quite similar to today, but maybe a degree or two cooler with little thermal chance. However, the decaying front will have introduced lower dewpoints to at least the northern half of the area, so heat indices will be closer to 100 or a little below. Central VA (i.e. Charlottesville area) will have to be monitored, because dew points there may be similar if not higher than today and could result in heat indices close to advisory criteria. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... Sunday evening and night will have to be monitored as a weak impulse may be riding the ridge across the Great Lakes into PA, in addition to low level theta-e advection. Have maintained low POPs across the north through the night to account for any showers or storms which may propagate into the area. Otherwise still muggy. Monday still has the potential to be one of the more impactful days of the next few in terms of heat and thunderstorms although much uncertainty remains. Have made little change to the going forecast. A front will be approaching from the northwest late, although the best forcing and shear will remain north of the area. Some storms may propagate into the area from the NW, but scattered storms could also develop in the hot and humid airmass, especially with north and westward extent. A Marginal Risk for severe weather is in place. Air temperatures will be in the mid to upper 90s, with heat indices potentially exceeding 105. The chance of storms will linger into Monday night. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Temperatures and humidity will remain quite elevated with no real relief in sight. In addition, a stalled front draped over the area will serve as a focus for waves of scattered showers and thunderstorms. Any upper-level disturbances riding by in the flow aloft could enhance this threat, but are difficult to pinpoint from a timing perspective this far out. It is especially important to remember heat safety during particularly prolonged heat events such as the one currently getting underway. Also, this type of heat and humidity do not usually go quietly, so stay tuned to later forecast updates for any strong thunderstorm potential during the upcoming week. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... VFR conditions overnight. Few concerns for Sunday-Sunday night with high pressure. A front will approach late Monday and could bring some scattered thunderstorms. Generally westerly flow at or below 10 knots is expected Tuesday, becoming increasingly erratic as a stalled front sets up over the area. Sub-VFR is possible in any showers or thunderstorms that develop. && .MARINE... A few storms may cross the waters this evening which could contain strong wind gusts. Light and variable flow expected again Sunday and Sunday night. Brief surge of SW winds possible on the wider waters during the evening. Gradient winds will likely increase Monday ahead of a cold front. Do not have high confidence on reaching Small Craft conditions, but its within the realm of possibilities. Will continue to leave the wording in the synopsis. Thunderstorm chances increase Monday as well, which may have a greater risk of locally high winds. Not much of a pressure gradient is expected over the waters into the middle portion of the week, which should keep winds below Small Craft Advisory thresholds. && .CLIMATE... Record highs and max lows... Sunday... DCA...101 in 2010...84 in 2011 BWI...101 in 2010...82 in 2010 IAD... 99 in 2010...78 in 2010 Monday... DCA...100 in 1930...79 in 1965 BWI...100 in 2010...77 in 1887 IAD... 98 in 2010...76 in 1965 Tuesday... DCA...103 in 1930...79 in 1987 BWI...101 in 1940...80 in 1940 IAD....98 in 2012...76 in 2005 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ UPDATE...WOODY! PREVIOUS...ADS/DFH is the U.S. government's official web portal to all federal, state and local government web resources and services.