Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
255 PM EDT Wednesday Jul 29 2015
Synopsis...a cold front will cross the area Thursday night. High pressure
will build for the weekend and hold through early next week.
Near term /through Thursday/...very warm and humid today with
dewpoints in the middle 70s. Scattered-numerous showers and isolated T-storms
ongoing primarily over NE Maryland. Similar to last night convection is
expected to wind down during the night with patchy dense fog
developing again. Lots of clouds will keep things very warm and
sultry with lows barely dropping below 80f in the district.
Cold front currently moving through the Midwest will enter the forecast
area around 18z Thursday and should clear the forecast area by 03z Friday.
Front will be losing much of its punch but it appears there could
be a quick band of -shra/thunderstorms and rain right along or just behind the
Short term /Thursday night through Saturday/...12z model suite has the
cold front placed just southeast of the County Warning Area by 12z Friday. Any
lingering precipitation with the front should remain to the south as the
frontal boundary stalls and eventually dissipates over the
weekend. Surface high pressure builds in from the west in the wake.
The region will remain at the southern fringe of broad closed low
over Canada...with the shortwave energy rounding the low remaining
well to the north. As such...expecting dry weather Friday and Friday night.
12z GFS suggesting light precipitation over northeastern areas of the County Warning Area
Sat afternoon with a shortwave just to the north. Will keep things dry
for now though during this time with lack of surface forcing currently
Quick shot of cold air advection in the wake of the front on Friday drop 850mb
temperatures to around 15 degrees celsius...resulting in highs generally in
the 80s. The cooler airmass will be short lived as the high builds
in...with 850mb temperatures rebounding back to near 20 degrees celsius by
Sat afternoon. Lows Friday near normal...with highs nearing 90 on
Saturday. Dew points in the 60s Sat should keep heat indices well below
Long term /Saturday night through Wednesday/...quiet weather pattern
for sun into Monday with high press dominating conditions behind a
cold front. The front lingers off the Delaware-Maryland-Virginia coast as it
weakens... therefore cannot rule out some showers to the southeast and east
of our County Warning Area. Shortwave trough could bring some afternoon showers on Monday
and Tuesday... but confidence with it is low at this time... so have kept low
probability of precipitation. Another front approaches on Wednesday increasing the chance of
showers and thunderstorms for this day. Temperatures will near normal sun and
gradually increasing into he low 90s for Wednesday.
Aviation /19z Wednesday through Monday/...chance of a shower or
T-storm until 00z tonight. Patchy dense fog developing late
tonight at the usual trouble spots. Cold front will cross the area Thursday
VFR conditions Friday and Saturday. Winds generally 10 kts or
less...shifting from the northwest Friday to a westerly flow Sat.
Marine...srly winds expected to increase tonight over the Bay and
continue through the day Thursday. Small Craft Advisory was expanded to cover the entire
length of the Bay.
Brief period of Small Craft Advisory gusts early Friday morning on the Chesapeake
Bay...with all waters becoming sub-Small Craft Advisory by Friday after. Sub-Small Craft Advisory conditions
then lasting into the weekend.
District of Columbia...none.
Marine...Small Craft Advisory from 6 PM this evening to 7 PM EDT
Thursday for anz530>534-537-539>541-543.