Area Forecast Discussion
Issued by NWS Sterling, VA
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Issued by NWS Sterling, VA
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-- Discussion containing changed information from previous version are highlighted. --102 FXUS61 KLWX 160117 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 917 PM EDT Sat Jun 15 2024 .SYNOPSIS...-- Changed Discussion --High pressure builds over the Mid-Atlantic through Sunday, then move offshore next week. A warm front will lift through the region early in the week, ushering in a prolonged period of hot weather.-- End Changed Discussion --&& .NEAR TERM /THROUGH SUNDAY NIGHT/...-- Changed Discussion --Dry and pleasant conditions continue as high pressure slowly drifts off to the east. Light winds are expected tonight with only some thin passing cirrus. Therefore temperatures should approach the dew points, with 50s across much of the area and low to mid 60s for the urban areas and closer to the Chesapeake Bay. Some of the colder mountain valleys could dip into the 40s. This will be the coolest night for the foreseeable future. While some patchy fog is possible in the valleys, there is not a strong signal in guidance, and there was likely substantial drying that took place today, limiting low level moisture. Afternoon temps warm a couple of degrees for Sunday. Fair weather cumulus clouds give us partly cloudy skies during the day, then mostly clear at night. Milder Sunday night as lows settle only in the mid to upper 60s.-- End Changed Discussion --&& .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... Aloft, a building mid- level ridge will be centered across NC/VA to start the week. Surface high off of Cape Cod moves further east into the Atlantic, though the axis of the ridge extends to its southwest, across the Outer Banks/Carolina coastline. This results in light southerly flow across our area for Monday afternoon, with slightly veered southwest winds west of the Blue Ridge, and more southeast winds east of I-95. The bay breeze is expected to develop early in the afternoon. The first day of hot temperatures starts as highs reach the low to mid 90s, with mid to upper 80s in the mountains. Trapped higher dew points in the valleys out west, combined with the hot temperatures are forecast to produce heat indices around 100. Heat Advisories might be needed for areas along the Potomac River and surrounding highlands west of the Blue Ridge for Monday afternoon. Elsewhere, heat indices are forecast between 95-100, and should remain below Advisory criteria. The one area we`ll have to look closely at is the immediate Western Shore where the bay breeze brings dew points closer to 70F. Still, this yield heat indices between 100-105 for a few hours, and that falls just below the Advisory threshold for areas east of the Blue Ridge. Limited instability and southwesterly winds in the Alleghenies allow isolated to scattered afternoon thunderstorms. These storms are most likely to remain terrain locked, and dissipate in a short period of time. Most of the convection dissipates by sunset. Dry, very mild Monday night as lows settle in the upper 60s to low 70s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Strong upper level ridging will remain overhead throughout the long term period, with dry conditions and well above normal temperatures expected. At the surface, high pressure builds over the region throughout the week. The main weather hazard for next week will be above normal temperatures. High temperatures east of the Alleghenies will rise well into the 90s each day with increased humidity leading to warming heat indices and record high temperatures possible. Heat indices in the upper 90s are expected with lower to mid 100`s possible. As the ridge axis pivots over the area, southerly winds will shift to southeasterly. This will lead to temperatures on Wednesday being a degree or two cooler compared to Tuesday. With winds shifting to southeasterly, relative humidities will increase leading to continued heat index concerns. Temperatures will continue to warm Thursday and Friday with highs in the mid to upper 90s. Higher elevations will stay in the 90s. Heat advisories may be needed at some point during the long term. While mostly dry conditions are expected for most of next week, a stray afternoon shower or sprinkle cannot be ruled out for those in the westernmost portions of the forecast area on Tuesday. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/...-- Changed Discussion --VFR conditions expected through Monday as high pressure moves north of the area, then offshore into the western Atlantic. Northerly winds this evening become southeast to south Sunday into Monday. Scattered cumulus will be favored during the typical diurnal cycle. VFR conditions are expected both Tuesday and Wednesday with hot and dry conditions expected at all terminals. Winds remain light, blowing 5-10 knots, out of the south/southeast-- End Changed Discussion --&& .MARINE...-- Changed Discussion --Northerly winds continue to lessen tonight, and slowly turn easterly. Winds turn southeast to south Sunday and Monday, with SCA conditions possible each late afternoon and evening due to southerly channeling in the middle Chesapeake Bay and Lower Tidal Potomac. Southerly channeling will lead to possible SCA conditions both on Tuesday and Wednesday evenings. Outside of gusty winds, hot and dry conditions are expected both days.-- End Changed Discussion --&& .TIDES/COASTAL FLOODING... Tide levels are forecast to increase at the start of the week due to strengthening southerly flow. The most likely location that could reach minor flood is Annapolis during the early Tuesday morning high tide cycle. Other locations are forecast to reach Action Stage. By mid week the winds are forecast to lessen, which should allow tidal anomalies to remain stable and decrease slightly. && .CLIMATE... Hot temperatures are expected next week. Below is a list of record high temperatures for June 17th through 21st, the year the record was set, and the current forecast high temperatures for those days. RERs are currently only issued for DCA, IAD, BWI, and MRB, but other sites are shown for reference. Monday Jun 17th Climate Site Record High Forecast High Washington-National (DCA) 99F (2022) 93F Washington-Dulles (IAD) 96F (2022) 95F Baltimore (BWI) 96F (2022+) 93F Martinsburg (MRB) 98F (1939+) 93F Charlottesville (CHO) 97F (2022) 94F Annapolis (NAK) 96F (1939) 88F Hagerstown (HGR) 96F (1952) 95F Tuesday Jun 18th Climate Site Record High Forecast High Washington-National (DCA) 97F (1944) 96F Washington-Dulles (IAD) 94F (2018+) 96F Baltimore (BWI) 97F (1957+) 94F Martinsburg (MRB) 99F (1943) 94F Charlottesville (CHO) 96F (2014+) 94F Annapolis (NAK) 96F (1957) 89F Hagerstown (HGR) 95F (1957) 95F Wednesday Jun 19th Climate Site Record High Forecast High Washington-National (DCA) 99F (1994) 94F Washington-Dulles (IAD) 98F (1994) 94F Baltimore (BWI) 99F (1994) 91F Martinsburg (MRB) 96F (1994+) 93F Charlottesville (CHO) 97F (2018) 93F Annapolis (NAK) 96F (1993) 88F Hagerstown (HGR) 97F (1994) 95F Thursday Jun 20th Climate Site Record High Forecast High Washington-National (DCA) 99F (1931) 95F Washington-Dulles (IAD) 97F (1964) 95F Baltimore (BWI) 100F (1931) 93F Martinsburg (MRB) 98F (1931) 93F Charlottesville (CHO) 98F (1933) 94F Annapolis (NAK) 98F (1988) 88F Hagerstown (HGR) 98F (1931) 95F Friday Jun 21st Climate Site Record High Forecast High Washington-National (DCA) 99F (2012) 98F Washington-Dulles (IAD) 98F (1988) 98F Baltimore (BWI) 100F (2012+) 95F Martinsburg (MRB) 102F (1931) 95F Charlottesville (CHO) 99F (1933) 96F Annapolis (NAK) 100F (1988) 91F Hagerstown (HGR) 97F (1923) 96F + indicates that value has been reached on multiple years, with the year displayed being the most recent. && .LWX WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --DC...None. MD...None. VA...None. WV...None. MARINE...None.-- End Changed Discussion --&& $$ SYNOPSIS...DHOF NEAR TERM...ADS/KRR SHORT TERM...KRR LONG TERM...AVS AVIATION...ADS/AVS/KRR MARINE...ADS/AVS/KRR TIDES/COASTAL FLOODING...KRR CLIMATE...LWX