Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Baltimore Maryland/Washington District of Columbia
907 PM EDT Monday may 25 2015
high pressure will remain offshore this week. A southerly flow
will bring warm humid conditions to the middle Atlantic through
Friday. Showers and thunderstorms will be possible each afternoon
and evening beginning Tuesday and lasting through the end of the
Near term /through Tuesday/...
An upper level ridge will move further off the East Coast tonight.
Middle-high level clouds will move into The Highlands late tonight from
the activity in the Tennessee Valley. As upper ridge moves further off
the coast expect associated subsidence inversion to weaken further
and allow scattered showers and T-storms to develop in the afternoon.
Models suggest some convection west of the Appalachians will move
into our area under a southwest steering flow. New convection
could also develop east of the Blue Ridge mountains GFS plot of 850 mb
equivalent potential temperature shows a maximum from Montgomery
County southward through Dulles to kcho suggesting another
possible area of convective initiation.
Short term /Tuesday night/...
the middle-Atlantic will be under SW flow aloft with the ridge in
the Atlantic and multiple disturbances are expected to ride near
or over The Highlands Tuesday afternoon. The storm motion will be
close to 180 so there wont be much eastward progression. Areas
east of the Blue Ridge should stay dry into Tuesday afternoon.
Flow veers to 220 by late afternoon and scattered showers and
thunderstorms may move into the western suburbs of District of Columbia and
Baltimore by sunset. Shear and instability will be marginal due to
the ridge still influencing the area and cloud cover. Any
thunderstorms should stay sub-svr.
Long term /Wednesday through Monday/...
early Summer warmth and moisture will be the main weather words for the
2nd half of the weak. High pressure off the CST and frontal boundary east of the
MS river will keep the east CST in warm humid air. Models are putting out
some likely probability of precipitation. It is hard to want to raise Summer cnvtcn probability of precipitation to
that level several days in advance - for the time being will keep probability of precipitation in
Clouds will be on the increases Tuesday and remain through Thursday. This will keep
insolation down...but moisture/srly flow will also be keeping
nighttime warmth in. Highs will be in the mu80s...lows in the mu60s
xcpt l70s in the cities.
A cold front will stall across the eastern half of the region
Thursday night and Friday...allowing for additional showers and
thunderstorms to develop. Low temperatures Thursday night and
high temperatures Friday could still be 7 to 10 degrees above
The cold front is expected to briefly return northward as a warm
front Friday night before a second cold front...moderately-strong...
approaches the region Saturday. Showers and thunderstorms will
continue to be a threat Friday night and Saturday along the cold
front. Low temperatures Friday night and high temperatures
Saturday could be 10 degrees above normal...reaching the upper 60s
and near 90...respectively.
The cold front should slowly push through the region Saturday
night into Sunday. The European model is slower than the GFS
in doing this. Nonetheless...the chance for showers and
thunderstorms will linger throughout the period. Lows Saturday
night and highs Sunday will still be above average.
A wedge of high pressure will build southward along the East
Coast...helping to cool conditions down a little. However...
overrunning moisture from the south and passing middle-level
disturbances to the north could bring another threat for rain
showers. Thunderstorms should be limited. Temperatures may be a
few degrees above normal each period.
Aviation /01z Tuesday through Saturday/...
VFR conditions expected today and tonight. -Shra/thunderstorms in the vicinity possible
Tuesday afternoon mainly at kiad and kcho.
VFR majority of the time Tuesday ngt-Thu. Rain shower/thunderstorm will
be possible... especially in the afternoon/Erly evening. Srly winds will gust
into the l20s during the afternoon.
MVFR or IFR conditions possible at all terminals Thursday night
and Friday with showers and thunderstorms. Winds generally southwest
5 to 10 knots with a few higher gusts.
S winds will persist across the waters tonight through Thursday.
Mixing during the afternoon will lead to Small Craft Advisory conditions across
lower Potomac and ches Bay south of Pooles Island. Winds should
subside tonight across the upper tidal Potomac and Chesapeake Bay
north of Pooles Island. This trend will continue Tuesday and
Srly flow will continue over the waters Tuesday ngt-Thu. Small Craft Advisory in effect Tuesday
night for the lower ptmc/main portion of the Bay. This will likely need to be
extend into Wednesday. Rain shower/thunderstorm will be possible as well.
No marine hazards expected Thursday night through Friday.
District of Columbia...none.
Marine...Small Craft Advisory until midnight EDT Tuesday night for
Small Craft Advisory until 6 am EDT Wednesday for anz532>534-