Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
955 am EDT Tuesday Oct 21 2014
a cold front will move through the middle Atlantic region this
afternoon. Low pressure will persist along the coast through
Thursday. High pressure will return for the end of the workweek
and into the weekend.
Near term /through tonight/...
as of 13z...1010mb surface low over Lake Ontario with an attendant cold
front stretching over western PA and eastern Ohio. Scattered light rain is
moving eastward through central WV...and may impact the eastern WV
Panhandle by early afternoon.
The upper trough will drop southeastward from the Great Lakes into western PA
and WV through this afternoon...while a surface cold front moves
through the forecast area. As it does...shower activity is
expected gradually increase in coverage and move across the area.
Based on current radar and hrrr/WRF models...any precipitation
should be confined to the areas along and west of the Blue Ridge
through middle afternoon...then spreading eastward to the metropolitan areas late
afternoon or early evening. Airmass will be relatively dry...with
surface dew points in the upper 40s to low 50s. Surface temperatures
should reach well into the 60s...and may touch 70 along and east
of I-95. Air aloft will be very cool due to the upper low...which
will help increase overall instability in spite of marginal
surface dew points. Modified 12z kiad sounding yields SBCAPE
between 400-500 j/kg...enough for a few potential isolated
Probability of precipitation generally decrease slowly tonight west to east (east of the
Allegheny Front with upslope rain continuing) as the upper low center
shifts to the Delaware-Maryland-Virginia. Min temperatures mainly upper 40s inland under the
cold core low (upr 30s in the alleghenies and low 50s near shore).
Short term /Wednesday/...
Wednesday...low pressure merely drifts east from the Delaware-Maryland-Virginia
coast. Probability of precipitation persist in the alleghenies for upslope and east of
I-95 from wrap around precipitation. Gusty northwesterly flow from the now cutoff
low. Expect gusts 35 to 40 miles per hour...particularly in the late
Long term /Wednesday night through Monday/...
blustery weather looks to be in store Wednesday night and Thursday...especially in
the eastern part of the forecast area. Low pressure GOES vertically stacked
off the New Jersey CST west/ high pressure building over OH/KY. This will create a
strong pressure gradient and brzy/windy conds. Isolated rain shower will be possible as
well..agn in the eastern part of the area. Low temperatures in the 40s.
Skies should be clearing during Thursday as the low slowly drifts towards
Long Island but suspect it will still be brzy given the pressure gradient.
Greater sunshine should also help to destabilize the lower levels of the
atmosphere and bring wind to the surface. High temperatures in the u50s to lm60s.
Aftr Thursday weather should get better and better. High pressure replaces the
departed low along the eastern Seaboard Friday through the weekend...and into
the beginning of the new weak. Each day should be a little warmer than
the one b4...starting west/ the lm60s Friday to the lm70s Monday. Lows in
the lm40s everywhere xcpt the cooler Highlands.
Aviation /14z Tuesday through Saturday/...
VFR prevails into this afternoon ahead of an approaching upper level
low. Likely rain and isolated thunderstorms this afternoon and
evening with periods of MVFR visibilities across the terminals.
Amendments possible to refine timing of any precipitation and
development of thunderstorms. Scattered showers persist tonight as the low
crosses the area. Strong northwesterly flow Wednesday with gusts around 30
knots by the late afternoon.
Cloudy Wednesday night but ceilings expeceted to be VFR. Brzy northwest winds expeceted Wednesday night
and Thursday. VFR/no probs Friday and Sat.
flow becoming westerly late this morning as low pressure approaches
from the northwest. Rain and isolated thunder this evening over
the Bay. Northwesterly flow increases through Wednesday with gusts at least
30 knots by the late afternoon. Gales possible Wednesday night as the
low lingers off the Delaware-Maryland-Virginia.
Small Craft Advisory will likely be issued for Wednesday night and Thursday. We'll have to keep our
eyes out for the possiblity of gusts reaching gale levels.
The weekend is looking quite good for marine activities - sunny
skies...plsnt temperatures...light winds. Water temperatures still in lm60s.
anomalies have dropped to just over one half foot at sensitive
locations. Coastal flooding is not expected.
District of Columbia...none.
Marine...Small Craft Advisory from 6 am to 6 PM EDT Wednesday for