Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
311 FXUS61 KLWX 301354 AAA AFDLWX Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 954 AM EDT Thu May 30 2024 .SYNOPSIS... High pressure will gradually build toward the area through Friday night, before progressing offshore on Saturday. High pressure will remain offshore through early next week. && .NEAR TERM /THROUGH TONIGHT/... One last shortwave-trough will cross the area late today and tonight generating clouds and perhaps a brief shower or sprinkles, mainly across northern areas. Removed the PoPs across the south and the mention of thunder as air mass appears too dry and the equilibrium levels too shallow based on the 12Z IAD sounding to generate thunderstorms. Previous afd... Longwave troughing remains in place along the East Coast this morning. A shortwave evident on water vapor imagery over the Great Lakes will dive southeastward into the base of the trough later today, eventually passing overhead this evening. As ascent ahead of this trough overspreads the area, there should be an uptick in cloud cover this afternoon, but the disturbance should struggle to produce precipitation in the unseasonably dry post- cold frontal airmass that will be in place (dewpoints only in the 40s). A stray shower or storm can`t be ruled out this afternoon across the Virginia Piedmont, but most locations should remain dry. High temperatures today should only reach into the low-mid 70s (60s mountains). A northwesterly breeze will accompany the below normal temperatures. The aforementioned shortwave trough will start to move off to our east tonight. Large scale subsidence in the wake of the departing trough will encourage high pressure to start to build toward the area from the Great Lakes. Clear skies, light winds, and low dewpoints will lead to an ideal setup for radiational cooling. Temperatures should drop back into the 40s in most locations tonight, with 30s possible in the typically cooler mountain valleys. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... High pressure will build toward the area on Friday, before eventually becoming centered overhead Friday night. The high will shift offshore on Saturday as upper ridging starts to build in aloft. Sunny skies are forecast for both Friday and Saturday. High temperatures are expected to reach into the mid 70s on Friday. As the high moves offshore on Saturday, winds will turn southerly which will lead to a slight warming trend with highs near 80. Friday night will be another cool night, with temperatures again dropping back into the 40s for most. Cloud cover will start to stream in from the west Saturday night, and a few showers may be possible across western MD or the WV Panhandle late Saturday night. The increasing clouds and southerly winds will result in warmer temperatures Saturday night, with lows generally in the upper 50s to near 60. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... By the end of the weekend, showers and thunderstorm chances will increase for the Mid-Atlantic. Numerous shortwaves will traverse the area Sunday through the middle portion of next week. A few highlights of the period are Tuesday into Wednesday, where some machine learning probabilities are elevated for the potential for a few strong to severe thunderstorms as a result of a cold front passage across the area. Expect showers and thunderstorm chances to be common over the next several days in the long-term period with temperatures in the low to mid 80s for much of the week. Winds will remain fairly light throughout the week outside of any strong thunderstorms or showers that traverse the area. Overnight lows will continue to meander in the mid to upper 50s to low 60s throughout the week. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... VFR conditions are expected at the terminals through the day Saturday. No precipitation is expected through Saturday. Winds will be out of the northwest today, and may gust to around 15-20 knots. Winds will become northerly on Friday, and then southerly on Saturday. Brief sub-VFR instances will be possible for some of the terminals Sunday and Monday afternoons and evenings. Otherwise, VFR conditions will be most common with southwest winds remaining below 10-15 knots for the afternoon and evening. && .MARINE... Northwesterly winds are expected over the waters today. SCAs remain in effect through this afternoon. After a brief decrease in winds this evening, SCA conditions return on the Bay and lower Tidal Potomac later tonight into early Friday in northerly flow. Sub-SCA conditions are expected tomorrow afternoon through Saturday, with winds light out of the north Friday afternoon, and then light out of the south on Saturday. Sub-SCA winds are expected Sunday into Monday with a chance for a few showers and isolated thunderstorms for the afternoon and evening hours. Cannot completely rule out the need for a Special Marine Warning for any strong storms that cross the waters during that period. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 5 PM EDT this afternoon for ANZ530>543. Small Craft Advisory from 2 AM to 11 AM EDT Friday for ANZ530>534-537>543. && $$ SYNOPSIS...LFR NEAR TERM...LFR SHORT TERM...KJP LONG TERM...ADM AVIATION...LFR/ADM MARINE...LFR/ADM