Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
542 FXUS61 KLWX 030110 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 910 PM EDT Tue Sep 2 2025 .SYNOPSIS... High pressure will progress offshore on Wednesday. A cold front will approach the area from the west on Thursday. A stronger cold front will move through on Saturday. High pressure will build back in early next week. && .NEAR TERM /THROUGH WEDNESDAY/... Clear skies, light to calm winds, and high pressure will lead to ideal conditions for radiational cooling. We have lowered our overnight temperatures by 2 to 3 degrees given the aforementioned factors. Low temperatures will drop into the middle 40s to the 50s. Some patchy fog may be possible, especially in sheltered mountain valleys. An upper low will lift off to the northeast Wednesday. A much stronger upper low will drop southward into the western Great Lakes. We`ll be located between these two disturbances and dry conditions are expected as a result. The lone exception may be across far southwestern portions of the forecast area, where a stray afternoon shower may be possible as a weak shortwave approaches from southwestern Virginia. Temperatures and dewpoints will both remain below normal, with highs in the upper 70s/low 80s, and dewpoints in the 50s. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... The aforementioned upper low will drop southeastward across the Great Lakes Thursday morning, before later turning northeast as it interacts with another potent disturbance dropping down within northwesterly flow toward the base of the trough. This will drive a cold front toward the area from the Ohio Valley on Thursday. This front will then wash out overhead as it loses upper level support (which will be moving off to our northeast). Southerly flow ahead of the system will advect warmer and more humid air into the area. When coupled with height falls aloft, this will result in increasing instability. Flow aloft will also be on the increase. Model soundings show around 500 J/kg of MLCAPE and around 40 knots of shear. As a result, any thunderstorms that form on Thursday should be well organized (as either multicells or supercells), and a resultant threat for strong to severe thunderstorms exists. This threat currently looks to be greatest along and to the west of I-95. There is currently a Marginal Risk for severe thunderstorms for Thursday into Thursday evening. Temperatures will be warmer on Thursday, with highs making it well into the 80s. It will also feel a bit more humid, with dewpoints climbing back into the lower 60s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Upper level troughing pivoting over the eastern CONUS will push a cold front through the forecast area early Friday ahead of a strong cold front pushing through Saturday evening. Showers and thunderstorms are possible Saturday afternoon and into the evening as the cold front pushes through the forecast area. In the wake of the cold front, surface high pressure builds over the Mid- Atlantic from the west Sunday and into early next week. Temperatures gradually warm Friday and Saturday ahead of a cold front with high temperatures rising into the 80s for most of the area. Those at higher elevations will stay in the upper 60s to 70s both days. Overnight low temperatures on Friday will be in the 60s for most with higher elevations dipping into the upper 50s. In the wake of a cold front, low temperatures Saturday night will be in the 40s and 50s with only those near the metro areas staying in the low 60s. High temperatures Sunday and Monday will be in the 70s for most with higher elevations staying in the 60s. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... VFR conditions are expected at the terminals through Thursday. A thunderstorm could be possible Thursday afternoon or evening as a decaying cold front approaches from the west. Winds will turn out of the southeast this evening, and then south on Wednesday. Stronger southerly winds appear possible on Thursday, with gusts to around 20 knots possible. VFR conditions and southwest winds gusting around 15 knots are expected on Friday. Showers and thunderstorms are possible across the terminals on Saturday as a cold front pushes across the Mid- Atlantic. Sub-VFR conditions are likely during showers and thunderstorms. Southwest winds Saturday morning shift to northwest in the wake of the cold front, gusting up to 15 knots in the afternoon. && .MARINE... Sub-SCA level winds of varying directions are expected over the waters tonight. Winds will become southerly Wednesday and gradually pick up in magnitude through the day, potentially nearing low-end SCA levels by Wednesday night. SCAs appear likely within southerly flow on Thursday. Small Craft Advisories are likely Friday through early Saturday morning as winds gust 15 to 20 knots across the waters. Winds diminish slightly on Saturday, will SCA criteria winds possible in the afternoon. && .TIDES/COASTAL FLOODING... Water levels hold somewhat steady overnight. Annapolis will likely be the only location that approaches minor flood stage. A flip to southerly flow Wednesday should allow for further rises in water levels. Confidence in Annapolis reaching minor flood increases Wednesday night. Peak water anomalies appear to occur Thursday night ahead of a front in strong southerly flow. More locations may reach minor flood, and some guidance has Annapolis approaching moderate flood. Water levels should decrease somewhat Friday as the front passes. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...KJP NEAR TERM...KLW/KJP SHORT TERM...KJP LONG TERM...AVS AVIATION...AVS/KLW MARINE...AVS/KLW TIDES/COASTAL FLOODING...KLW