Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
910 PM EDT sun may 19 2013
Synopsis...
a warm front will slowly lift north of the area tonight into
Monday morning. A weak middle-level trough will move through Monday.
High pressure builds over the western Atlantic Tuesday and
Wednesday...with southerly return flow providing warm temperatures
to the region. A cold front will approach from the Great Lakes
late this week.
&&
Near term /through Monday/...
high pressure located over the northern Atlantic has led to
southerly flow across the middle Atlantic. A stationary front is
currently draped across Virginia state and will move northward as a warm
front by Monday afternoon. The warm front nosed northward late this
afternoon and mixing occurred to break up some of the low ceilings.
As surface heating ceased clouds increased again this evening. Surface
analysis does not show a distinct stationary front but believe it is
situated north of the Bay and across central Virginia. Overnight...
little movement of warm front and therefore little change to
current airmass and scattered showers will continue across central
Virginia. Heavier showers to the south have waned this evening and
do expect that to continue overnight. Saturated low levels
elsewhere will lead to drizzle and patchy fog overnight and Monday
morning.
An upper level low will move across the region Monday and help mix
the low ceilings. Showers and thunderstorms are possible across the
County Warning Area in the afternoon and evening. Southerly flow will continue to
usher in high precipitable water air and forecast soundings show cape values around
500 j/kg with a slow storm motion. Heavy rain will be possible in
thunderstorm activity.
&&
Short term /Monday night through Wednesday/...
low clouds and fog will continue to be a factor into the morning hours.
However...the may sun angle will gradually erode the satd layer...permitting
the fnt to jump north of area by the afternoon. South of this front...a
warm and a modestly humid airmass will be in place. Maximum temperatures in
the 80s each day although clouds may inhibit temperatures from reaching
80f in some locations on Monday.
NAM/GFS/ECMWF forecast a middle-level shortwave trough to mv through the middle-
Atlantic region on Monday. Lift/moisture ahead of the trough in conjunction
with daytime heating will support diurnal convection over the County Warning Area.
Probability of precipitation highest toward central Virginia/southern Maryland but still in chance range.
Middle-level ridge builds overhead Tuesday and Wednesday after the shortwave
trough exits the area. Coverage of showers and storms will be low
Tuesday and Wednesday due to an absence of organized lift and a strengthening
subsidence inversion. Mav/met diverge here. Kept forecast dry for most
of the I-95 corridor and chesepeake Bay as weak steering flow will
limit how far east convection propagates once initiated over the
mts.
&&
Long term /Wednesday night through Sunday/...
shortwave trough and associated cold front will approach from the
Great Lakes/Midwest regions Wednesday night and Thursday before passing through
the area on Friday. Chances for showers and storms will accordingly
increase late in the week and will be highest with frontal passage. Above
normal temperatures ahead of the cold front will trend much cooler in
wake of frontal passage Friday into the weekend.
&&
Aviation /01z Monday through Friday/...
IFR conditions expected this evening and into Monday morning. Southerly
flow will continue through this period and low ceilings and visibilities
expected.
IFR conditions likely to start the day Monday before morning stratus/
fog mix out from west to east. Predominately VFR conditions expected Monday
afternoon although brief restrictions in rain showers/thunderstorms and rain are possible.
Diurnal fog/low clouds possible at night and early in the morning each
day in the midweek. Chances for rain showers/thunderstorms and rain will be low during this
time.
&&
Marine...
Small Craft Advisory advisory canceled for this evening.
Southerly flow will continue over the waters but should stay under
Small Craft Advisory criteria. Showers and drizzle expected with low ceilings
overnight. An upper level disturbance will cross the region Monday
and showers and thunderstorms will be possible. Slow storm motion
and high moisture will lead to heavy rain in activity.
Light southerly flow Ely in the week will strengthen later in the week.
Small Craft Advisory conditions possible by Thursday...when a cold front approaches from
the northwest.
&&
Tides/coastal flooding...
no tidal flood issues expected in the near future /tngt or even
tomorrow/.
Water levels should tick upward Ely next week with southerly flow
persisting and a waxing gibbous moon. This far out...still some
uncertainty if positive anomalies increase enough to reach minor
threshold.
&&
Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...none.
&&
$$
Update...Sheffield
