Area Forecast Discussion
Issued by NWS Sterling, VA

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870 FXUS61 KLWX 171903 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 303 PM EDT Sun Jul 17 2016 .SYNOPSIS... Weak high pressure will remain over the area through Monday morning. A cold front will approach from the northwest late Monday and cross the region on Tuesday. High pressure will build in Wednesday and remain in place through Saturday. A cold front may cross the region Sunday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Weak stationary front remains in the area but it continues to dissipate. Heights continue to build and there are no disturbances passing through over the next few hours. Thus...the suggestion of isolated showers/t-storms over our southern zones for late this afternoon into early this evening has not been included in the forecast as believe it is a 10 percent probability event. That having been said...with the front having not reached the area...instability is present so something stray could pop up based on instability alone. Otherwise...tonight will be mostly clear after cumulus dissipates with lows in the 60s and lower 70s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Things look more active on Monday but much uncertainty remains. Front pushing southeast from Canada looks to move through early Tuesday...a bad time if you want convection. What most likely would happen is that storms well ahead of the front associated with a weak leading shortwave may develop to our west and move into our area towards evening on Monday before dying out or diminishing to showers overnight. There is 25-35 knots of 0-6km shear and decent CAPE...but also hints of a westerly flow which may try to suppress convection. Bottom line...not alot of confidence in potential thunderstorms on Monday aft/eve but potential definitely exists especially in our NW zones. With the SW to W flow ahead of the front, temps should spike into the mid 90s in our warmer locales. Heat indices should stay near or below 100 however. On Tuesday...any showers/storms depend on just how fast the front moves through...as well as a push of drier air aloft. Right now have them mostly in our southern zones...which makes sense given expected frontal position. Temps will be on their way down. Tuesday night into Wednesday...Canadian high pressure will provide a cooler and drier air mass with sunshine. Lows in the 50s and 60s with highs in the 70s and 80s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As high pressure remains in the area Thursday expect dry and comfortable weather, with near seasonable temperatures (M/U 80s), and relatively low humidity (dewpoints U50s/L60s). We turn hot (highs in the M90s) but stay dry Friday. Though, humidity gradually increases as southwest flow develops, which will make it begin to feel slightly more uncomfortable. Cold front then approaches the area next weekend. Still some uncertainty with how far the front pushes through the area. Current forecast has chance pops returning Saturday and Sunday afternoon with front nearby and hot/humid atmosphere. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... VFR and dry conditions through this evening. Some patchy fog possible again Monday morning, but coverage will be much less than this morning. Next chance of showers/thunderstorms will arrive Monday afternoon through Tuesday with next frontal system. Reductions below VFR possible along with potential for damaging winds...best chance MRB. A stray storm may pop up Tuesday but odds are low. VFR conditions prevail Wednesday through Friday under high pressure. && .MARINE... Sub-SCA conditions expected through Monday morning across all waters. Southerly flow increases tonight and into Monday with marginal SCA conditions expected late Monday into Monday night out ahead of next frontal system. Isolated to scattered showers/thunderstorms also possible Monday into Tuesday. NW flow behind front Tuesday-Tuesday night may also bring SCA conditions with northerly channelling. High pressure builds in Wednesday then remains through Thursday. Winds should gradually increase Friday as southerly flow redevelops over the area. && .TIDES/COASTAL FLOODING... Anomalies are a little on the high side and should increase a bit ahead of the next front. Sensitive sites (Annapolis) may briefly reach minor thresholds on Monday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from noon to 9 PM EDT Monday for ANZ530>543. && $$ SYNOPSIS...RCM NEAR TERM...RCM SHORT TERM...RCM LONG TERM...MSE AVIATION...MSE/RCM MARINE...MSE/RCM TIDES/COASTAL FLOODING...RCM

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