Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
974 FXUS61 KLWX 071334 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 934 AM EDT Sun Jul 7 2024 .SYNOPSIS... A front stalls south of the area today, with dry and less humid conditions in wake of the front. Heat, humidity, and daily thunderstorm chances return for much of the upcoming week as the front lifts north across the area Monday. && .NEAR TERM /THROUGH TONIGHT/... MID-MORNING UPDATE... Today will be the quietest in what feels like a while, with only isolated PoPs restricted to southern Maryland and neighboring waters. Northwesterly flow behind the front stalled just to the south and east has been observed channeling over portions of the Chesapeake Bay, resulting in sporadic gusts around 18 kts and waves around 2-3 ft in places. A Marine Weather Statement has been issued for a few hours this morning to account for this. Current thinking is this gustiness should subside later this morning. Otherwise, forecast appears on track. PREVIOUS DISCUSSION FOLLOWS... A weak front has mostly pushed through early this morning, as noted by the northwest winds and lower dew points in its wake. The front is going to stall just east and south of the area today, keeping most of us dry. However, a few showers or thunderstorms could develop along the front throughout the day. This would mainly be over the Chesapeake Bay and Eastern Shore. Hot temperatures in the low to mid 90s this afternoon will be accompanied by considerably less humidity. Mid to high-level cloudiness persists over the area today, producing partly to mostly cloudy skies. Mild overnight lows in the upper 60s to mid 70s, though some urban centers along I-95 will barely drop below 80F. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... The stalled front to our south quickly lifts north through the area Monday as a warm front. Southerly flow kicks in by Monday afternoon, ushering in a deep moist airmass. PWATs increase to around 1.7-1.9" Monday, then well over 2" Tuesday. Dew points consistently stay in the low to mid 70s to start the week. Afternoon highs in the low to mid 90s result in peak heat indices of 100-105 across the area. Daily afternoon showers and thunderstorms return to the forecast Monday. The greater focus will be west of US-15 to start the week, then become widely scattered Tuesday. Locally heavy rainfall, gusty winds, and frequent lightning strikes will be the main threats from most storms that develop. Shower/thunderstorm activity dissipates in the evening, though some convection could linger into the overnight. Mild and muggy overnight lows in the low to mid 70s. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... The current NHC track shows the remnants of Beryl tracking from the Central Mississippi Valley toward the Great Lakes Wednesday into Thursday as a Tropical Depression. As this occurs, a mid-latitude trough is expected to combine with Beryl`s remnant circulation to form a broader upper trough over the Great Lakes. Meanwhile, guidance has a 600+ decameter upper ridge forming offshore in the western Atlantic, with a strong Bermuda high in place at the surface. Such a surface pattern will maintain a warm and very humid airmass across the region within continual southerly flow. A weakening frontal boundary associated with the trough over the Great Lakes is expected to track into the area on Wednesday into Thursday, and then eventually stall out as it runs into the influence of the strong Bermuda high offshore. Diurnally driven showers and thunderstorms will be possible each afternoon and evening during the long term period, especially in the vicinity of the frontal boundary, where low-level convergence will be maximized. Flooding could eventually become a concern, particularly in urban areas, as the potential is there for multiple days in a row with thunderstorm activity in the vicinity of the front within an environment characterized by precipitable water values of 2+ inches. Temperatures in the long term period should start out above normal on Wednesday, with highs in the lower to middle 90s, and then settle back toward normal, with high temperatures generally in the upper 80s for most from Thursday onward. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... VFR conditions expected through the start of the week. North winds this morning in wake of a passing front become light/variable this afternoon as high pressure quickly crosses the area. By this evening, light south winds prevail. A warm front lifts north through the area Monday, bringing the return of daily afternoon showers and thunderstorms. Most of the convection Monday looks to focus near CHO/MRB, with more isolated activity at the other terminals. Coverage of showers/storms increases Tuesday. Any storm that moves over a terminal could produce brief periods of reduced visibility and gusty winds. Most of the convection should dissipate each evening. Prevailing VFR conditions and southerly winds are expected on both Wednesday and Thursday. Afternoon or evening thunderstorms may lead to temporary restrictions either day. && .MARINE... Northwesterly flow behind the front stalled just to the south and east has been observed channeling over portions of the Chesapeake Bay, resulting in sporadic gusts around 18 kts and waves around 2-3 ft in places. A Marine Weather Statement has been issued for a few hours this morning to account for this. Current thinking is this gustiness should subside later this morning, after which sub-SCA conditions are expected for the rest of today and tonight as weak high pressure crosses the area. Winds will be variable at times today. A warm front lifts north across the local waters Monday, bringing a return of southerly winds at 5-10 knots. Winds remain below SCA criteria through Monday night. Southerly channeling Tuesday is likely to produce SCA conditions Tuesday evening into Tuesday night as wind gust to 20 knots in the open waters of the Chesapeake Bay. Isolated showers and thunderstorms are possible over the waters Monday afternoon, then an increase in coverage is expected for Tuesday. Any strong storm will be capable of producing wind gusts in excess of 35 knots and frequent lightning strikes. Southerly flow is expected over the waters on both Wednesday and Thursday. Winds may approach low-end SCA levels in channeled southerly flow either day. && .TIDES/COASTAL FLOODING... Light northerly winds this morning in wake of a weak front that stalls to our south. This should bring anomalies down for today. However, the front lifts north of the area Monday, bringing a return to southerly flow for much of the week. Elevated tide levels are likely by mid week. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...KRR NEAR TERM...CAS/KRR SHORT TERM...KRR LONG TERM...KJP AVIATION...KJP/KRR MARINE...KJP/CAS/KRR TIDES/COASTAL FLOODING...KRR