Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
107 am EDT sun Jul 13 2014
high pressure centered along the Virginia coast will shift offshore
tonight and set up southerly winds to begin the new week. A cold front
will cross the area Tuesday. An upper level low will then persist over
the eastern United States through late in the week.
Near term /until 6 am this morning/...
diurnal downtrend in coverage this evening. Middle level clouds
persist...which along with return flow make for a warm night...min
temperatures mu 60s inland...lm 70s urban and near shore.
Short term /6 am this morning through 6 PM Monday/...
Sunday...hotter and more humid than Saturday. Expected greater
coverage and stronger thunderstorms. Maximum temperatures around 90f
north/west/southwest of the District of Columbia metropolitan...with low 90s northern Virginia and
central/southern Maryland including balt/wash metropolitan. Still little shear to
maintain storms...but once the cap is broken...expect multicell
development to be maintained.
Weak cold front approaches Sunday night with shear increasing
overnight and allowing a nocturnal thunderstorm threat. Chance/likely
probability of precipitation spread in from the west after midnight. The cold front stalls
over the area Monday with likely probability of precipitation for thunderstorms due to
strong moisture influx from Bermuda high and frontal boundary
drifting/stalled over the area. Slight risk for area is justified
with lifted index -4 to -6c. Bulk shear is still weak...with the the
upper jet not approaching until evening.
Long term /Monday night through Saturday/...
a stalled front across eastern Maryland and central Virginia will
become the focal boundary for another round of frequent showers and
strong thunderstorms everywhere Tuesday and in the eastern areas
into Tuesday evening. With the main upper level energy push
expected later Tuesday afternoon and Tuesday night...the instability
ahead of the front and the upper level wind energy will quickly
allow showers and thunderstorms to develop across the region.
Very heavy rainfall with any activity. Relatively steep lapse
rates could translate to damaging winds with the strongest
thunderstorms. Temperatures will top out near 90 before the
showers and thunderstorms become frequent. Much of the shower and
thunderstorm activity will push to the I-95 corridor...southern
Maryland and adjacent Chesapeake Bay Tuesday evening.
More stable air will be ushered into the region from the northwest
as high pressure builds southeastward. Temperatures will be 7 to
10 degrees cooler Wednesday. A pleasant night is in store
Wednesday night with temperatures near or slightly below normal
with dry air settling in from the northwest.
There is a slight chance of a few rain showers in the Potomac
Highlands and Shenandoah Valley Thursday afternoon and Thursday
night as we will see some weak upper level energy move across from
the west and a slight onshore and upslope flow develop with a
surface high sitting just offshore. Temperatures will be slightly
below normal with highs in the lower 80s and lows in the upper
We increase the chance of showers and thunderstorms Friday and
Saturday as the high offshore Ushers in more humid and warm air from
the Atlantic and southeast and a continuous stream of upper level
energy pushes in from the west and southwest. Temperatures Friday
should be slightly below normal or near normal...but by
Saturday...temperatures may work their way above normal.
Aviation /05z Sunday through Thursday/...
VFR tonight. Greater thunderstorm coverage Sunday and continues
Heavy showers and strong thunderstorms could bring diminished
conditions to any terminal Tuesday. Aside from strong wind gusts
in showers and thunderstorms...southwest to westerly winds will
average less than 10 knots with gusts to 15 knots Tuesday but
should veer around to the northwest and north- northwest Tuesday
night with frontal passage.
High pressure building into the region Wednesday.
southerly flow 10-15 knots increases to 20 knots over the Main Channel through
tonight. Small Craft Advisory up until 6am Sunday. Another Small Craft Advisory late Sunday
afternoon through Sunday evening.
A cold front approaches late Sunday night through Monday...with
likely strong thunderstorms by late Monday. Secondary cold front
Tuesday with more strong thunderstorm threats.
No hazard marine conditions expected Tuesday through Wednesday.
water levels have increased to 2/3rds foot as southerly flow
strengthens. This modest increase and a full moon is all thats
needed to reach minor threshold at Annapolis for high tide early
this upcoming morning. Have issued coastal Flood Advisory.
The morning tide is the higher of the two astronomically. We will
be in a similar situation Monday morning...W/ perhaps SW District of Columbia getting
in on the act.
District of Columbia...none.
Maryland...coastal Flood Advisory from 5 am to 8 am EDT this morning for
Marine...Small Craft Advisory until 6 am EDT early this morning for
Small Craft Advisory from 3 PM this afternoon to 2 am EDT
Monday for anz532>534-537-540-541-543.