Area forecast discussion National Weather Service Baltimore Maryland/Washington District of Columbia 339 PM EDT Tuesday Jun 18 2013 Synopsis... a weak low moves will continue to move east across the southern middle- Atlantic through the evening hours. A weak cold front will sag south through the area this evening into the overnight. High pressure will build behind this front late tonight through Wednesday....remaining off the northern middle- Atlantic shore through this weekend. && Near term /until 6 am Wednesday morning/... Flash Flood Watch retracted for much of the area...remaining until 6pm for areas I-95 and east...as well as central Virginia. As of 19z...one frontal boundary now moving southeast from north-central Virginia and southern Maryland. This takes the heavy rain and wind threat to the Bay. Trends suggest this threat should last only another hour or so. Surface low pressure will continue to develop as it moves across southeastern Virginia through this evening...drawing activity farther southeast. Evening temperatures mild with dewpoints in the upper 60s to low 70s. Will need to monitor the scattered thunderstorms and rain over eastern OH/I-70. However...weak steering flow will keep this activity away from the Potomac Highlands for at least a couple more hours...enough to drop the Flash Flood Watch for now. Tonight...boundary sags south from the Mason-Dixon. Plenty of moisture around for showers redevelopment in spite of lack of heating. Drier air behind this boundary should enable min temperatures in the upper 50s west of the Blue Ridge to low to middle 60s east. && Short term /6 am Wednesday morning through 6 PM Wednesday/... surface high builds across the northern mid-Atlantic...pushing frontal boundaries south. Light north flow will keep temperatures below normal...expect highs in the upper 70s to around 80f. Dry and mostly sunny. && Long term /Wednesday night through Tuesday/... near normal temperatures in return flow midweek through the weekend. Isolate/scattered afternoon thunderstorm activity in the terrain west from the Blue Ridge each day. Low pressure will be exiting the CST Wednesday morning west/ high pressure building in from the upper Midwest. Very plsnt days/ngts expeceted Wednesday and Thursday west/ highs in the l80s..lows ranging from the m50s in The Highlands to the m60s in the cities. && Aviation /20z Tuesday through Sunday/... moderate rain showers for the terminals tapers off into the evening hours as thunderstorm chance moves east across the Chesapeake Bay. Frontal boundary will continue to push southeast this evening. VFR conds and light flow expected outside of potential morning fog through the weekend. && Marine... showers and thunderstorms will produce strong gusty winds into the evening hours. North winds occur behind a weak cold front tonight but are expected to also remain below Small Craft Advisory. Winds expeceted to remain below Small Craft Advisory values through the weekend. && Lwx watches/warnings/advisories... District of Columbia...Flash Flood Watch until 6 PM EDT this evening for dcz001. Maryland...Flash Flood Watch until 6 PM EDT this evening for mdz007-011- 013-014-016-018. Virginia...Flash Flood Watch until 6 PM EDT this evening for vaz025-036- 037-050>056-502. WV...none. Marine...none. && $$ Jackson