


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. --656 FXUS61 KLWX 071410 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1010 AM EDT Mon Jul 7 2025 .SYNOPSIS... The remnant low pressure from Chantal will weaken as it crosses the area today, while a cold front approaches from the northwest. The front will drop closer to the area Tuesday and may stall nearby through the weekend. && .NEAR TERM /THROUGH TONIGHT/...-- Changed Discussion --Current surface and radar analysis places the remnants of Chantal over southeastern VA this morning. A prominent shield of moderate to heavy showers is evident generally east of the I-95 corridor. Some isolated showers are possible further west this morning, but should be nothing of consequence. The remnant low will continue to track northeast through the day before passing northeast by early evening. There may be a bit of a gap in the heavy rainfall as the system continues to weaken along with the diurnal minimum in instability. By late morning into the afternoon, greater instability and convergence may occur near the Chesapeake Bay, with embedded heavy convective elements redeveloping. The strongest signal for heavy rain is on the Eastern Shore, but CAM guidance suggest localized totals up to 5 inches could occur on the western shore as well. This system has a history of producing much more than that in NC and will be accompanied by an anomalously moist atmosphere with deep warm cloud layers that will support very efficient rain. Therefore have issued a Flood Watch for potential flash flooding along the Chesapeake from 10 AM until 6 PM, which rainfall should have departed. Farther west, some clearing will take place. A cold front will be approaching from the Great Lakes, but should remain northwest of the area. However, a prefrontal trough and terrain circulation may support isolated to scattered shower/thunderstorm developing during the afternoon. At this time, severe weather and flooding appear unlikely with this activity. Any convection will likely dissipate as it pushes toward the metro areas during the early evening. Remnants of upstream convection may move into the Allegheny Front this evening as well, but should dissipate with loss of daytime heating. Speaking of which, cloud cover should keep highs in the 80s near and east of I-95, with lower 90s to the west. Heat indices may reach the upper 90s. Other than a few showers along the Alleghenies, tonight should largely be dry. Some patchy fog could develop. The muggy dew points will limit lows to the lower and mid 70s except in the higher elevations.-- End Changed Discussion --&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Shower and thunderstorm coverage will be much greater Tuesday afternoon and evening as the front moves closer to the area and subtle ripples move through the WSW flow aloft. A hot and humid airmass will support moderate to strong instability, so a few severe thunderstorms with damaging winds may occur. However, modest shear and moist profiles (limiting DCAPE) may limit the severe threat. High precipitable water values and deep warm cloud layers will support heavy rain. There may be enough flow aloft for storms to be somewhat progressive, but any sort of merging or backbuilding on the mesoscale would produce a localized flooding threat. Before storms arrive, heat index values may reach the upper 90s and lower 100s. While marginal, Heat Advisories can`t be ruled out for portions of the area. Dry weather likely returns by the second half of Tuesday night. There`s some uncertainty on where the front ends up Wednesday, but could bisect the area. Model consensus places the highest chance of storms across the southern half of the area, but all locations could see some rain. The main threat will be heavy rain/localized flooding given the continued moist environment, but a localized damaging storm can`t be ruled out. Very warm and humid conditions continue with highs in the upper 80s and lower 90s. Storms will likely follow a diurnal trend again. && .LONG TERM /THURSDAY THROUGH SUNDAY/... A frontal boundary will remain stalled across the region through the end of the week. Several pieces of upper level energy and affiliated surface low pressure systems will move along this front. High precipitable water will fuel numerous showers and strong thunderstorms nearly each afternoon and early evening. The multiple rounds of showers and thunderstorms, energy and moisture available could lead to severe weather and possible flooding. High temperatures each day will be near average. && .AVIATION /14Z MONDAY THROUGH FRIDAY/...-- Changed Discussion --MVFR to IFR ceilings remain across much of the area this morning. Steadier and more moderate rains associated with the remnants of Chantal will graze the metro areas today, with the greatest chance of heavier showers and thunderstorms near BWI/MTN. Ceilings should improve by midday from west to east. Already starting to see CHO break out, but still have some SCT clouds around 1000 feet, which likely linger for a few hours. Winds will likely be somewhat variable due to the weakening low pressure system. Additional isolated to scattered thunderstorms may form over the mountains this afternoon, potentially affect MRB and CHO. It`s uncertain if these reach the metro areas, but IAD and perhaps DCA will be most at risk, so maintained PROB30 groups. Tonight should be dry with light winds. There isn`t a strong signal for fog, but can`t rule out some patchy spots. Thunderstorm coverage will likely be fairly widespread Tuesday afternoon and evening with heavy rain and gusty winds being threats. Patchy fog could again form Tuesday night. Thunderstorm chances will continue each day Wednesday through Friday, focused on the afternoon and evening. Some low clouds or fog could develop during the overnight and morning periods given the moist airmass.-- End Changed Discussion --&& .MARINE...-- Changed Discussion --The remnants of Chantal are currently pushing towards the waters and will bring some heavy rain and embedded thunderstorms through this afternoon. This could bring down some gusty winds here and there, which will be handled with short-fused hazards from here on out. Generally sub-SCA winds are expected Tuesday, though some isolated gusts to 20 kt can`t be ruled out. More widespread coverage of thunderstorms is expected during the afternoon and evening hours, which could bring strong wind gusts. Sub-SCA winds are most likely Wednesday through Friday. Any strong thunderstorms crossing the waters could result in Special Marine Warnings.-- End Changed Discussion --&& .TIDES/COASTAL FLOODING... South to southeast winds have caused anamolies to rise to around one foot or a little higher. This is resulting in minor flooding at Annapolis. After the remnants of Chantal pass today, water levels are forecast to decline a bit through the middle of the week. No additional flooding is forecast, although some locations may reach action stage. && .LWX WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --DC...None. MD...Flood Watch until 6 PM EDT this evening for MDZ008-011-014-017- 018-508. VA...None. WV...None. MARINE...Flood Watch until 6 PM EDT this evening for ANZ530.-- End Changed Discussion --&& $$ SYNOPSIS...ADS NEAR TERM...ADS/CJL SHORT TERM...ADS LONG TERM...KLW AVIATION...ADS/KLW/CJL MARINE...ADS/KLW/CJL TIDES/COASTAL FLOODING...ADS