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. --598 FXUS61 KLWX 200005 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 805 PM EDT Wed Jun 19 2024 .SYNOPSIS... High pressure will remain anchored offshore through the week, resulting in a prolonged period of heat. The hottest days will be Saturday and Sunday. && .NEAR TERM /THROUGH THURSDAY/...-- Changed Discussion --No changes made to the near-term forecast. High pressure will remain directly overhead through Thursday promoting large scale subsidence/sinking motion and no convection in the local area. Given the position of the high, low-level flow will be off the Atlantic. This coupled with a slight increase in high-level cirrus will result in slightly lower temperatures than those of the past view days. Tds are also fcst to drop today potentially below 60F and remain in the comfortable range through Thursday. No heat headlines planned for today or Thursday. Lows will remain near or above 70.-- End Changed Discussion --&& .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... High pressure will drift westward Friday while sfc to 850 mb high moves further inland causing winds to veer more from the south or southwest direction, coming from a continental trajectory as opposed from oceanic direction. Temperatures on Friday are expected to soar into the upper 90s and may approach the century mark across western areas. Heat Advisories may be needed for western areas. Still keeping fcst dry for most Friday, though cannot rule out isolated convection across the Mason-Dixon. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... The hottest temperatures of the ongoing heat wave are anticipated this coming weekend, with daytime highs climbing into the mid-upper 90s. Some locations may even reach 100 on Sunday. Dewpoints will also increase into the upper 60s and lower 70s, making it feel more humid. Peak heat indices in excess of 100 look to be a good bet for much of the forecast area this weekend. There will also be lesser relief at night, with lows only dropping into the mid-upper 70s to the east of the Blue Ridge. Gradual height falls aloft combined with daytime heating may lead to a few pop up afternoon or evening thunderstorms on Saturday, but overall coverage is expected to remain low. By Sunday into Monday, an upper trough will approach from the Great Lakes, leading to increased chances for afternoon and evening thunderstorms. Ensemble guidance shows a fair amount of variance with respect to the timing of this disturbance and its associated cold frontal passage, but the majority of solutions show the front passing through Monday. Depending on the timing of this system, there could be a threat for severe thunderstorms as flow aloft increases atop a very hot and humid airmass. If the front were to progress slower and hold up to our north, it could potentially be very hot (near 100) again Monday, but more solutions than not show the front passing through sometime Monday, leading to slightly cooler conditions (highs in the lower 90s). There`s a greater consensus amongst guidance that we`ll be within a post-cold frontal airmass by Tuesday, leading to dry conditions. It will still be hot however, with highs forecast to be in the lower 90s. && .AVIATION /00Z THURSDAY THROUGH MONDAY/...-- Changed Discussion --Lots of high clouds through Thursday, then clear on Friday. SE winds around 10kt during the day becoming light south during the night. Prevailing VFR conditions and southerly winds are expected at the terminals on both Saturday and Sunday. A pop up afternoon or evening thunderstorm may be possible either day.-- End Changed Discussion --&& .MARINE...-- Changed Discussion --Southeast winds occasionally gusting to 18-20 knots in the middle Chesapeake Bay and Lower Tidal Potomac early this evening. These winds should abate by late evening. Sub-SCA winds through Thursday morning. A few hours (2-4 hrs) of SCA gusts are possible each evening Thursday and Friday, across the southern waters. Otherwise, S to SE winds 10 to 15kt. Winds may reach low-end SCA values in channeled southerly flow both Saturday and Sunday afternoon/evening. SMWs may also be needed for any thunderstorms that move over the waters.-- End Changed Discussion --&& .CLIMATE... Hot temperatures are expected much of this week and especially this coming weekend. The hottest days appear to be Friday through Sunday when several records could be in jeopardy. Below is a list of record high temperatures for Jun 21st, 22nd, and the 23rd and the year the record was set, and the current forecast high temperatures for those days. RERs are only issued for DCA, IAD, BWI, and MRB, but other sites are shown for reference. Friday Jun 21st Climate Site Record High Forecast High Washington-National (DCA) 99F (2012) 95F Washington-Dulles (IAD) 98F (1988) 97F Baltimore (BWI) 100F (2012+) 95F Martinsburg (MRB) 102F (1931) 94F Charlottesville (CHO) 99F (1933) 96F Annapolis (NAK) 100F (1988) 90F Hagerstown (HGR) 97F (1923) 96F Saturday Jun 22nd Climate Site Record High Forecast High Washington-National (DCA) 101F (1988) 97F Washington-Dulles (IAD) 99F (1988) 97F Baltimore (BWI) 100F (1988) 95F Martinsburg (MRB) 102F (1933) 93F Charlottesville (CHO) 101F (1933) 98F Annapolis (NAK) 101F (1988) 91F Hagerstown (HGR) 100F (1988) 95F Sunday Jun 23nd Climate Site Record High Forecast High Washington-National (DCA) 98F (1988) 98F Washington-Dulles (IAD) 96F (1988) 99F Baltimore (BWI) 97F (2010) 98F Martinsburg (MRB) 100F (1934) 95F Charlottesville (CHO) 100F (1894) 100F Annapolis (NAK) 98F (1988) 95F Hagerstown (HGR) 98F (1988) 96F && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...LFR NEAR TERM...CPB SHORT TERM...CPB LONG TERM...KJP AVIATION...CPB/KJP MARINE...KRR/CPB/KJP CLIMATE...LFR