Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1054 am EDT Sat Jul 4 2015
low pressure will ride along a stationary front over the area
today. The front will push south as a cold front into North
Carolina on Sunday. High pressure will build overhead Sunday and
move off the coast Sunday night. Deeper moisture will return to
the area Monday and Tuesday bringing unsettled conditions.
Near term /until 6 PM this evening/...
as of 14z...one weakening low pressure was centered over western
Pennsylvania with a strengthening low just east of the Delaware-Maryland-Virginia.
The low over Pennsylvania will continue to fill while the low in
the Atlantic will head eastward through the remainder of today.
Looks like the bulk of stratiform rain has now passed the area.
However...some breaks are showing up in the overcast to the west
and the upper trough still has to come through aloft. This should
create just enough instability for some showers and a few
thunderstorms this afternoon. Storms should remain garden-variety.
Highs will be cool for July 4th...mostly 70s with perhaps a few
places especially south breaking 80.
Tonight...precipitation clears as do the clouds. Fog develops in typical
Piedmont and valley locations. Min temperatures low to middle 60s...upper 60s
Short term /6 PM this evening through 6 PM Sunday/...
brief high pressure. After patchy am fog breaks...sunny with a
light/variable flow and maximum temperatures middle 80s.
Long term /Sunday night through Friday/...
as high pressure moves off the coast Sun night moisture and
instability begin to return northward in deep layered srly flow with
showers expected to break out Sun night and continuing through Monday
night as a warm front lifts north through the area. Potential for
heavy rains due to high precipitable waters at or above 2.0 inches and since rains will
be near an upper level ridge axis. Localized flash flooding not
out of the question.
Drier SW flow establishes over the area late Tuesday and continues
through the end of next week. Lee-side troughs appear the only
mechanism to trigger convection. Otherwise...warmer and humid with
the risk of isolated-scattered diurnally driven convection each day.
Fronts appear to remain well north of the area next week. So
considerably warmer next week than it has been recently.
Aviation /15z Saturday through Wednesday/...
steadiest rain moving out at this time but low clouds linger.
Showers and a few thunderstorms espected to redevelop this
afternoon...with brief IFR ceilings/visible possible. After improving
again this evening...some patchy fog will affect inland sites
especially cho and mrb. Back to VFR all terminals on Sunday after
fog Burns off. Winds through Sunday remaining below 10
knots...with northeast flow today becoming more variable Sunday.
IFR ceilings appear likely for kcho late Sun night and early Monday in
rain improving to MVFR Monday afternoon. Low clouds again Monday night
as a warm front lifts through the area with IFR ceilings likely at
kbwi and kmtn.
Small Craft Advisory remains in effect...mainly for potential of some afternoon
gusts as low moves east and winds shift to the north. Winds will
become light/variable tonight and Sunday. Surface winds expected to
strengthen Tuesday-Tuesday night due to channeling srly flow. This may
require Small Craft Advisory.
District of Columbia...coastal Flood Advisory until noon EDT today for dcz001.
Maryland...coastal Flood Advisory until noon EDT today for mdz011-014.
Virginia...coastal Flood Advisory until noon EDT today for vaz054.
Marine...Small Craft Advisory until noon EDT today for anz532-540>542.
Coastal Flood Advisory until noon EDT today for anz535-538.
Small Craft Advisory until 6 PM EDT this evening for anz533-