


Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
103 FXUS61 KLWX 171845 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 245 PM EDT Fri Oct 17 2025 .SYNOPSIS... Surface high pressure will remain overhead through tonight before moving offshore tomorrow. A potent low pressure system will pass through the Great Lakes Saturday night into early Sunday and the cold front associated with this system will pass through our area late Sunday into Sunday night. High pressure will briefly return early next week before a couple reinforcing cold fronts pass through during the middle and latter portions of next week. && .NEAR TERM /THROUGH TONIGHT/... A dry northwest flow ahead of building high pressure will continue to bring sunshine and dry conditions through this afternoon. Surface high pressure will remain overhead through tonight. Light winds and low dewpoints will set the stage for radiational cooling again. However, it will not be as chilly as last night (warmer start, and some high clouds moving in overnight). Low temperatures will range from the mid to upper 30s in the colder valleys and rural areas, to the upper 40s and lower 50s in the urban areas and near Bay/Potomac River. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... High pressure will move offshore Saturday and a return southerly flow will develop behind the departing high. The southerly flow will allow for a warmer afternoon, with highs ranging from the upper 60s to lower 70s near the waters, to the upper 70s and lower 80s in the valleys of the Potomac Highlands (downsloping flow). A potent low will move into the Great Lakes Saturday night into Sunday morning and a cold front will approach from the west during this time. A southerly flow will increase, allowing for mild conditions. Moisture will begin to increase causing more clouds, but dry conditions will most likely persist. The cold front will slowly pass through the area from west to east later Sunday afternoon into Sunday evening. Showers are expected to develop with the frontal passage west of the Blue Ridge Sunday afternoon, and east of the Blue Ridge Sunday night. The upper-level trough axis is expected to swing toward a negative tilt around the time of the frontal passage. This means forcing will be strong along with a strong wind field aloft. Therefore, a line of gusty showers is most likely to develop late Sunday afternoon into Sunday evening along and just ahead of the cold front. With a very strong wind field aloft, it is not out of the question for some of these winds to mix down, causing a threat for damaging wind gusts. However, confidence is low at this time due to limited instability. Additional showers are possible overnight behind the cold front as the negatively tilted upper-level trough passes through. Some guidance is indicating a closed upper-level low can develop. If so, the showers will be more widespread during the overnight hours. && .LONG TERM /MONDAY THROUGH FRIDAY/... Strong cold front should have pushed east of the area early Monday morning with gusty post-frontal NW winds. Weak sfc high pressure builds in by the end of Monday. Another potent trough/closed low traverses the Mid-Atlc area Tue night bringing light rain showers Tuesday afternoon and evening with mountain rain showers continuing in favorable upslope flow and even perhaps a snowflake mixed in at times over the highest elevations as 850 mb temps drop between 0C and +2C. Broad trough pattern persists for the second half of next week keeping near normal to below normal temperatures. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR conditions are expected through Saturday. Northwest winds this afternoon will become light or calm tonight before turning southerly for Saturday. Increased moisture with southerly winds is expected Saturday night, but VFR conditions are most likely to persist. Stronger southerly winds are expected ahead of a cold front Sunday with gusts around 25 to 30 knots most likely. Showers are expected with the cold front later Sunday afternoon through most of Sunday night. A wind shift to the west and northwest is expected behind the cold front late Sunday night. SubVFR conditions are possible in showers Sunday night. Gusty post-frontal NW winds Monday, which diminish by Monday evening. Fair weather on Tuesday. && .MARINE... Winds will continue to diminish over the waters through this evening. Southerly winds will develop Saturday, but wind speeds should remain below SCA criteria. Southerly winds may channel up the Bay and lower Tidal Potomac Saturday night, and a Small Craft Advisory may be needed for those areas. Stronger southerly winds are expected Sunday into Sunday evening ahead of a cold front. A Small Craft Advisory will be needed. Winds may even approach gale-force, but confidence is lower due to the relatively cooler waters. Winds will turn to the northwest behind a cold front late Sunday night, and an SCA will be needed. Showers will increase in coverage, especially Sunday night. A line of heavier showers along the cold front may cause gusty winds, and Special Marine Warnings may be warranted. This is most likely to occur late Sunday evening. && .TIDES/COASTAL FLOODING... Higher anomalies in the southern portion of the Chesapeake Bay will surge northward tonight, and this may cause minor tidal flooding for sensitive areas (Annapolis) with the high tide cycle tonight. A southerly flow will develop Saturday and strengthen Sunday. This will continue to increase tidal anomalies along with the fact that a new moon is approaching on the 21st. Minor tidal flooding is expected for sensitive areas Saturday into Saturday night, and for most areas Sunday into Sunday night. There is the potential for moderate tidal flooding around Annapolis with the high tide cycles Sunday afternoon and Sunday night. Will continue to monitor. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ532>534-537-540-541-543. && $$ SYNOPSIS...BJL/CS NEAR TERM...BJL/CS SHORT TERM...BJL/CS LONG TERM...LFR AVIATION...BJL/CS/LFR MARINE...BJL/CS/LFR TIDES/COASTAL FLOODING...BJL