Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version |  Previous Version |  Graphics & Text |  Print | Product List |  Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
728 FXUS61 KLWX 271420 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1020 AM EDT Fri Jun 27 2025 .SYNOPSIS... A backdoor cold front will stall out over the area today, before returning northward as a warm front on Saturday. Another cold front may move through the area on Tuesday. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Main issue this morning is elevated showers and embedded thunderstorms which developed along an area of convergence aloft (around 850 mb) just south of Washington. The stationary nature of this forcing has resulted in some locally heavy rain, though not lasting too long in any one location. As the frontal zone stalls, the convergence will weaken by midday, which should then focus new convective development closer to the surface boundary along the Appalachians. Other areas northeast of the boundary continue to see areas of drizzle. Will likely be adjusting temperatures down a bit where the thickest cloud cover will reside through the day, meaning readings will stay in the lower to mid 70s. Previous discussion: A backdoor cold front has advanced to the far southwestern periphery of the forecast area this morning. This front will stall out along the spine of the Appalachians across most of our area, then arc southeastward across the Central Shenandoah Valley and Central Virginia. This will place the majority of the area within stable, marine influenced easterly low-level flow today. Thick low clouds are expected as a result, along with much cooler temperatures. High temperatures will only make it into the upper 70s and lower 80s for most. Temperatures will be a bit warmer along and west of the front with highs reaching into the mid 80s. The highest chance for thunderstorms this afternoon will be along the Allegheny Front and into the Central Shenadoah Valley and Central Virginia, where some breaks in the clouds may be possible on the warm side of the front. Showers and thunderstorms will form in response to daytime heating along the higher terrain as the backdoor front banks into the terrain. Forecast soundings show profiles with deep moisture, around 1000 J/kg of MLCAPE, light easterly flow at low- levels, and very weak flow aloft. With such a setup, concerns arise regarding the potential for storms to become anchored to the higher terrain as the light easterly flow will provide a persistent source of upslope flow and lift into the terrain, and storms won`t have much flow aloft or cold pool production to move them off of the ridgetops. Latest runs of the HRRR show a broad area of 1-3 inches of rain across our westernmost counties, with isolated totals of 3-5 inches. Other HREF members show similar solutions. As a result, a Flood Watch for flash flooding has been issued for the Alleghenies and Central Shenandoah Valley from 1 PM until 10 PM. Any storms that form will eventually start to drift eastward, but should weaken over time as they move into a more stable airmass further east. Activity should wind down relatively quickly after dark, with mainly dry conditions expected through the night.
-- End Changed Discussion --
&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... The aforementioned frontal boundary will return northward as a warm front on Saturday. Meanwhile, a disturbance at mid-upper levels will move eastward across the Great Lakes. Showers and thunderstorms appear possible Saturday afternoon, and the Storm Prediction Center has much of the area in a Marginal Risk for severe thunderstorms, with damaging winds being the primary threat. Temperatures will be warmer with the front lifting to our north, with highs climbing back into the lower 90s for most. Showers and thunderstorms may be possible again on Sunday, but coverage looks to be lower compared to Saturday. Temperatures will be warm once again, with highs in the lower 90s. && .LONG TERM /MONDAY THROUGH THURSDAY/... A surface low pressure system tracking northeast across the Great Lakes region and the associated warm front draped to the north will bring chances of showers and thunderstorms areawide on Monday. On Tuesday, the associated cold front will track across the forecast area with showers and thunderstorms likely ahead of the cold front. High temperatures Monday and Tuesday will be in the 80s to low 90s with overnight low temperatures expected to be in the 60s and 70s. In the wake of the cold front, conditions dry out as surface high pressure builds overhead. Temperatures will be slightly cooler with highs in the 80s for most. Those at higher elevations will stay in the 70s. Overnight low temperatures will be in the 60s for most with only those in the metros staying in the 70s. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
An area of showers with a few embedded thunderstorms has developed south of IAD/DCA this morning. Added in a VCTS for a few hours given convective towers near the 10 SM radius. However, lightning activity has diminished and will likely be able to remove this threat with the next amendment, as this activity is forecast to further weaken. IFR ceilings prevail at most locations this morning, and will struggle to clear out over the course of the day today. Some brief improvement to MVFR may be possible during the afternoon hours, but it`s possible that conditions stay IFR all day. While a thunderstorm can`t be completely ruled out during the afternoon or evening, it currently looks as though most of the storms should stay off to the west of the terminals. At this point, CHO would have the greatest chance for a late afternoon or evening storms. IFR ceilings are expected for all tonight, and some fog may also be possible at CHO and MRB. Conditions are expected to improve back to VFR on Saturday, with thunderstorms possible during the afternoon. Prevailing VFR conditions, with lesser, but non-zero chances for thunderstorms are expected on Sunday. Winds will be light out of the east today, light out of the southwest on Saturday, and light out of the northwest on Sunday. Sub-VFR conditions are possible at times on Monday due to shower and thunderstorm chances. Shower and thunderstorm chances increase Tuesday as a cold front moves across all terminals with sub-VFR conditions likely during thunderstorms. Southerly winds on Monday shift to northwesterly Tuesday evening in the wake of the frontal passage.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
Enhanced easterly flow behind a backdoor cold front is resulting in some isolated gusts to 18 kt, but otherwise winds should weaken into the afternoon as the front stalls. Sub-SCA level winds then are expected over the waters through this weekend. Winds will be out of the east today, southwest on Saturday, and then northwest on Sunday. Thunderstorms may be possible over the waters, especially on Saturday afternoon and evening, and to a lesser degree on Sunday. Southerly winds on Monday shift to northwesterly Tuesday evening in the wake of a frontal passage. SCA criteria winds are possible in the southern portions of the waters on Tuesday morning with sub-SCA criteria winds expected elsewhere. SMWs are possible during thunderstorms Tuesday evening.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING... Tidal anomalies will remain slightly elevated through the next several high tide cycles. This will keep water levels slightly elevated for the more sensitive tidal sites. Several sites may reach Action stage, and Annapolis may near Minor flood stage Saturday morning. && .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...None. MD...Flood Watch until 10 PM EDT this evening for MDZ509-510. VA...Flood Watch until 10 PM EDT this evening for VAZ025-026-503- 504. WV...Flood Watch until 10 PM EDT this evening for WVZ055-501>503- 505-506. MARINE...None.
-- End Changed Discussion --
&& $$ SYNOPSIS...KJP NEAR TERM...ADS/KJP SHORT TERM...KJP LONG TERM...AVS AVIATION...ADS/AVS/KJP MARINE...ADS/AVS/KJP TIDES/COASTAL FLOODING...LWX