Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
023 FXUS61 KLWX 191200 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 800 AM EDT Fri Jul 19 2024 .SYNOPSIS... A cold front will stall to the south this weekend before returning as a warm front during the early and middle part of next week. As a result, expect temperatures to remain at or slightly below normal with daily chances for showers and thunderstorms due to the front nearby. && .NEAR TERM /THROUGH TONIGHT/... The forecast is on track this morning with no changes needed. Will monitor trends regarding any pop up showers today. Previous discussion... High pressure builds in from the north today while a frontal boundary stalls to our south/southeast. The result will be mostly dry conditions for the area, though a few isolated showers and thunderstorms are possible in the Shenandoah Valley and along the terrain of the Blue Ridge and Allegheny Front late this morning into the afternoon. Temperatures are expected to be near normal, with highs in the 80s for much of the area and in the 70s for higher elevations. Lows tonight fall into the 60s for most, and the low 70s along the metros/waters. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... On Saturday, the stalled boundary to our south is expected to meander northward as a shortwave passes overhead. Precip chances will increase from southwest to northeast through the day, bringing much needed rainfall to the area. Cloud cover will keep high temperatures below normal, topping out in the low to 80s for most of the area. Rain chances drop off overnight as the shortwave exits and forcing is lost. Low temperatures will be a few degrees cooler than Friday, in the low to mid 60s for most. The front likely remains stalled to our south into Sunday, limiting PoPs to our southern zones. Expect coverage to be reduced compared to Saturday with subsidence on the back end of the exiting shortwave. Reduced cloud cover and southerly flow brings highs back to the upper 80s and low 90s. Clouds build in overnight resulting in milder lows, hovering in the 70s along and east of the I-95 corridor and mid-upper 60s expected elsewhere. && .LONG TERM /MONDAY THROUGH THURSDAY/... Showers and thunderstorms look to cement their place in the forecast each day next week as several waves of low pressure aloft pass over the region. The axis of the Bermuda Ridge builds into the far southwest Atlantic to start the week, and eventually over FL/GA and the Carolinas by mid week. This puts our area in a steady fetch of south to southwesterly flow that continually advects deep moisture from the Gulf of Mexico. An upper trough approaches from the west late in the week, though the exact timing and strength of this system varies. Rainfall is likely to be mostly beneficial, especially west of US-15 where extreme drought conditions are being observed. Locally heavy rainfall in the I-95 urban corridor could result in some flooding issues if storms persist over an area. Abundant cloud cover keeps highs near normal for late July, in the mid to upper 80s, with spotty low 90s. Overnight lows will be in the mid 60s to low 70s. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... VFR conditions are expected through this evening with light NE winds turning SE by tonight. Terminals remain dry today except maybe CHO as the stalled boundary to our south pops off some isolated showers. Sub-VFR cigs may move into CHO late tonight as said boundary advances slightly northward. All terminals could see some showers and thunderstorms (and brief sub-VFR conditions) Saturday afternoon and evening as a shortwave aloft passes through. Outside of convection, chances for sub-VFR elsewhere tonight into Saturday night have decreased as the boundary is expected to continue lingering to our south into Sunday. Afternoon showers and thunderstorms are possible again on Sunday, but other than CHO most terminals are expected to stay dry. Daily showers and thunderstorms return to the forecast for next week. The highest rain chances will be in the afternoon to early evening each day, with storms that move over a terminal likely to produce brief sub-VFR conditions. Outside of showers/storms, VFR conditions are expected in southerly winds around 5-10 knots. && .MARINE... NE winds turn E then SE by this evening. A frontal boundary is expected to remain stalled to our south today, with some gradual northward movement through the weekend. Some showers and thunderstorms will be possible over the waters both Saturday and Sunday as a result, though on Sunday shower activity will likely be restricted to the southern waters. Other than higher gusts associated with these showers and thunderstorms, sub-SCA criteria winds are expected. Southerly winds remain below SCA criteria Monday and for most of Tuesday. Daily showers and thunderstorms are expected next week, with some storms possibly producing wind gusts in excess of 35 knots and frequent lightning strikes. Stronger southerly channeling Tuesday night could produce SCA conditions in the open waters of the central Chesapeake Bay. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Small Craft Advisory until 10 AM EDT this morning for MDZ008. VA...None. WV...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ530>534-537-539>541-543. && $$ SYNOPSIS...DHOF/EST NEAR TERM...DHOF/CAS SHORT TERM...DHOF/CAS LONG TERM...KRR AVIATION...DHOF/CAS/KRR MARINE...DHOF/CAS/KRR