Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
227 PM EDT Sat may 25 2013
Synopsis...
high pressure will build into the middle Atlantic region through the
Memorial Day weekend. The high will move offshore Monday...and a
warm front will cross the area on Tuesday. An upper ridge then
builds through the rest of the week.
&&
Near term /through Sunday/...
17z surface analysis indicated about 1004 mb low pressure in the
Gulf of Maine...while 1030 mb high pressure was moving southward
through the Great Lakes and into the Ohio Valley.
Tight gradient between these two pressure systems have helped to
produce another windy day...gusting at or above 25 miles per hour at times. But as
high pressure continues to build in through the late
afternoon/evening...gusts should diminish particularly around
sunset.
Have seen few-scattered cumulus development this afternoon particularly along
the ridges and northern portion of the County Warning Area. But the atmosphere is
relatively dry and stable...so cumulus have been rather flat and have
not put much of a Dent in abundant sunshine today. Like wind
gusts...any clouds should diminish around sunset...leaving a
clear sky overnight.
Despite the sunshine and a downsloping flow east of the
mountains...temperatures have been slow to rise this afternoon and
middle 60s may be as high as we get for many areas. Normal is middle to
upper 70s. This will pave the way for another chilly night with
minima in the 40s east of the Blue Ridge and 30s west of there.
Will continue the frost advisory for The Highlands for minima in
the mids 30s...and with winds expected to drop off late tonight.
On Sunday...northwest flow continues but it should not be as windy
as today and the cool air mass should begin to modify.
Therefore...expect temperatures to rebound around 70 in the
afternoon with ample sunshine.
&&
Short term /Sunday night through Tuesday/...
high pressure is forecast to move off the coast on Memorial Day
Monday...resulting in a return flow to develop. May start to see
an increase in clouds especially Monday night to the north of a
warm front. This warm front will cross the County Warning Area on
Tuesday...instigating a more significant warming trend. With the
warm front and a return in moisture...there is a small chance of
convection late Monday night into Tuesday...but most areas may
wind up staying dry.
&&
Long term /Tuesday night through Saturday/...
above normal temperatures are expected middle to late week...perhaps
even into the weekend as an upper ridge builds over the eastern
states. Under the ridge...subsidence will likely put a lid on
convection...however can/T rule out isolated diurnally driven
storms over the mountains.
&&
Aviation /17z Saturday through Wednesday/...
wind will be the weather-related aviation impact through the rest
of the afternoon at the lwx terminals. With good
mixing...northwest winds of 15 knots will gust to 25 knots for the rest
of the afternoon. Gusts diminish after sunset as high pressure
builds in from the rest.
Aside from a small chance of thunderstorms Tuesday...no
significant weather is expected during the outlook period.
&&
Marine...
northwest winds continue this afternoon with low pressure in the
Gulf of Maine and high pressure building in from the west. Small
Craft Advisory continues...with occasional gusts around 25 knots
through the afternoon. Winds diminish some tonight...enough for
the Small Craft Advisory over the Upper/Middle tidal Potomac to drop. Will continue
with Small Craft Advisory over much of the Bay/lower tidal Potomac into Sunday for
20 knots gusts.
High pressure builds in through early next week. Will have to
watch southerly flow up the for gusts at or above 15 knots during the middle
week.
&&
Fire weather...
dewpoints in the 30s will remain over the area this afternoon. As
temperatures rise into the middle 60s...this may bring relative humidity values of
near 30 percent in some areas. This will occur as winds continue
to gust 20 to 25 miles per hour. However...fuel moistures are very high which
will limit an enhanced fire risk.
&&
Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...frost advisory from midnight tonight to 8 am EDT Sunday for
mdz501.
Virginia...frost advisory from midnight tonight to 8 am EDT Sunday for
vaz503-504.
WV...frost advisory from midnight tonight to 8 am EDT Sunday for
wvz501-503-505-506.
Marine...Small Craft Advisory until 6 PM EDT Sunday for anz530>534-
537>543.
Small Craft Advisory until 8 PM EDT this evening for anz535-
536.
&&
$$
Bpp
