Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
400 am EDT sun Aug 31 2014
Bermuda high pressure will persist through Tuesday with an active
pattern for the eastern Seaboard. A weak cold front will cross the
area Tuesday night...followed by high pressure.
Near term /through today/...
a broken line of showers west/ embedded heavy rain links up from the
Florida Gulf Coast to Lake Erie...just to our west. The synoptic
features creating this larger arrangement of activity is a complex
combination of weak kinks in the upper level flow. The parent
feature is an open wave kicker that is drifting across the northern
Great Lakes region...pulling the moisture axis up and over a
compact but strong upper ridge over the Carolina coast. The ridge
will be eventually supplying our area - and much of the deep
south...W/ prolonged period of abnormally warm/humid temperatures to
start off the month of sept.
Patchy low clouds will stream across the region as dewpoints level
off around their highest points in the l70s...W/ temperatures at or just
above these values. This is creating a humid environment even in
the overnight hours...W/ the increased cloud cover insulating this
high-humidity layer. This is the type of feel to the air we will
have for much of the upcoming week...espec the first half. Temperatures
will slowly/steadily climb back into the 80s heading into the middle
morning hours today. Like yesterday...the high amounts of cloud cover
will likely temper the potential highs - espec across the western/northern
halves of the County Warning Area. Along and southeast of I-95...the maximum expected highs
closer to 90 degree will probably be met west/ longer periods of
sunshine this afternoon.
Much of the incoming shower activity from the west will dissipate
as it approaches the higher terrain of the central Appalachians by dawn.
Into the Post-dawn hours...only a few showers will skirt the northwestern
sections of the County Warning Area. Toward the early afternoon hours...weak Lee
troughing could help develop pockets of shower/thunderstorm activity along
and east of the Blue Ridge/Appalachians but very localized. More coverage
and intensity is expected heading into the afternoon hours.
Reorganization of the best convective parameters will likely occur
toward the late afternoon/evening over the District of Columbia/balt I-95 corridor and NE...
either west/ diff heating boundaries and/or a localized Lee trough
axis sliding through the northern sections of the County Warning Area. Surface dewpoints will
be plenty high to steepen low level lapse rates in combination west/
temperatures in the M-u80s. MLCAPE will hover around 1000j/kg...W/
locally higher and some bulk shear in the 20-30kt range near this
region. Locally gusty/damaging winds possible west/ the strongest
activity and possibly rotation embedded west/in a linear complex.
Precipitable waters hovering in the 2-2.5" range this afternoon/evening will also give
localized areas the heightened potential for brief torrential
rains but possibly enough for flooding under training cells.
Short term /tonight through Tuesday/...
after the evening convection has dissipated off and moved east...
another regional batch of light/moderate range is tagged by near term
guidance as moving along the Mason-Dixon line as well - keeping
precipitation chances alive into early Monday. As the back end of this
feature passes by to the north...precipitation chances will remain in the
low chance range through Monday afternoon/evening across the eastern half of the County Warning Area
but mainly of a light/scattered nature...outside of a few thunderstorms. The
relative lack of activity and clearing skies from west-to-east
will allow temperatures to climb back into the u80s and some l90s for the
area on Monday afternoon...W/ dewpoints standing pattern in the u60s/l70s -
another muggy day for the area.
Weak ridging crosses the central middle-Atlantic Monday night into
Tuesday...making for a reprieve in thunderstorms for 12-18 hours. With
the Bermuda high in place...expect Tuesday to have the highest
temperature day since July. Maximum temperatures low to middle 90s across lower
The next cold front approaches late Tuesday and crosses that night.
With plenty of energy from the hot day...expect at least isolated
severe weather...particular for western zones that are prognosticated to get
the evening activity.
Long term /Tuesday night through Saturday/...
high pressure builds in behind with Continental air (not canadian)
so temperature remain above normal. Expect maximum temperatures around 90f
Wednesday through Friday. Return flow and active weather returns
late Friday into the weekend.
Aviation /07z Sunday through Thursday/...
high humidity levels are here for the next few days and are
already helping to produce localized MVFR ceilings...espec near the Maryland
ches Bay. Other pockets of high-end MVFR visibilities and ceilings are
dotting the map across inland areas as well...mainly affecting the
region through middle morning. Scattered showers/thunderstorms will become more possible
and widespread later this afternoon/evening but localized. Southerly winds will
persist into Monday...along west/ a few hit/miss showers as well through
Brief high pressure/VFR Tuesday on a hot day (max temperatures in the middle
90s). Scattered strong thunderstorms Tuesday night as a weak cold
front crosses the region. High pressure/VFR outside of potential
morning fog middle to late week.
southerly flow across the marine area through the weekend. Marine observation in the
low-middle teen gusts. It/ll be a simlr situation Sunday...though dont
think the mixing will be quite as good. In addition...potl thunderstorms and rain would
provide stronger wind gusts.
Sub Small Craft Advisory southwesterly flow Monday night through Tuesday. Weak cold front
brings westerly flow late Tuesday night through Wednesday. High pressure
overhead Wednesday night and Thursday.
departures at Annapolis are around 1 feet...and winds should
remain southerly...so anticipate addtl increases through the weekend. The
next high tide Sun morning will need to be watched for possible minor
flooding. Nonetheless...this will be an issue through the weekend with
new moon and southerlies.
BWI Airport has not hit 90f this month. Upper 80s are forecast
today. This would be the first August since 1984 that Baltimore did
not hit 90f. The only other such year in the Baltimore temperature
record is 1904.
District of Columbia...none.