Area Forecast Discussion
Issued by NWS Sterling, VA

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260
FXUS61 KLWX 211904
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
304 PM EDT Sun Apr 21 2019

.SYNOPSIS...
Low pressure will cross the area through tonight, lifting
northeastward toward southern New England Monday. High pressure
will build south of the region through Tuesday, before migrating
off the southeast coast through mid-week. A weak cold front will
sink southward from Pennsylvania on Wednesday, stalling to our
south through Thursday, then lifting northward as a warm front
on Friday as low pressure tracks across the Great Lakes towards
New England.

&&

.NEAR TERM /THROUGH TONIGHT/...
A cumulus field has increased across the area this afternoon
thanks to diurnal heating and an upper low moving overhead. A
few showers have been able to develop as well over western
Maryland the eastern panhandle of West Virginia. Hires guidance
continues to depict isolated to scattered showers developing this
afternoon and persisting into this evening for areas mainly
along and east of the Blue Ridge as the upper low passes over
the area. As colder air filters in aloft with the upper low
passing overhead, this has dropped the freezing level down to
around 6kft per the 12z IAD balloon. While not overly confident
in occurrence, can`t rule out a little graupel mixing in with
any overachieving showers. The majority of these showers will be
mainly light in nature and are expected to diminish this
evening with the loss of daytime heating and the upper low
shifting eastward. Lows overnight will bottom out in the middle
40s to lower 50s under mostly cloudy skies.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The upper trough and surface low will reside off the Delmarva
Peninsula Monday morning, tracking northeastward through the
day. This will yield clearing skies and warming temperatures as
high pressure builds south of the region. Highs on Monday will
reach into the lower to middle 70s. Temperatures will continue
to moderate through Tuesday as mid to upper level ridging crests
over the Mid Atlantic, and return flow increases as the
aforementioned high slides off the southeast coast. Lows Monday
night will be in the upper 40s to middle 50s, while highs on
Tuesday will extend well into the 70s, likely cracking 80
degrees along and south of the DC metro.

Clouds will be on the increase Tuesday evening ahead of an
approaching cold front to our north as low pressure passes
through the Great Lakes. Shower chances will also increase late
Tuesday night, but with the best dynamics to our north and no
significant moisture source, will carry chance POPs into
Wednesday morning.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A weak cold front will settle to our south on Wednesday, before
eventually stalling out. Slightly cooler, drier air will filter in
behind the front. Conditions should stay mainly dry, but a brief
shower can`t be ruled out. The highest chance for a shower should be
across central Virginia, where they`ll be located closer to the
surface front. Although appreciably cooler than Tuesday,
temperatures will be near normal for late April, with highs in the
upper 60s to low 70s.

By Thursday, a largely cutoff southern stream trough will progress
across the Deep South, while a smaller-scale northern stream
disturbance embedded in northwesterly flow tracks across the Upper
Midwest/Great Lakes. Much of the day Thursday looks dry, but chances
for showers will increase moving into the evening/overnight hours
as the forcing for ascent out ahead of the two aforementioned
features starts to overspread the area. Opportunities for showers,
and maybe even a brief thunderstorm will linger into Friday as the
northern steam disturbance moves overhead. A cold front will push
through Friday Night, ushering cooler, drier air into the area. High
pressure will build overhead for Saturday, resulting in dry
conditions.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
VFR conditions will dominate over the terminals through Tuesday.
An upper low will cross overhead through tonight, bringing the
potential for passing showers, mainly across our eastern
terminals (MTN/BWI/DCA). Chance of occurrence is too low to
include in the TAF, with a brief episode of MVFR VIS being the
primary consequence. High pressure will build south of the
terminals Monday through Tuesday, with light winds and dry
conditions prevailing. A weak cold front will sink southward
into the area late Tuesday night and into Wednesday morning,
increasing clouds and bringing the chance for showers.

Predominantly VFR conditions are expected on Wednesday and
Thursday. Intermittent sub-VFR conditions may be possible
Thursday Night into Friday as showers and potentially a few
thunderstorms move across the area.

&&

.MARINE...
Sub SCA winds will prevail over the waters through Tuesday. A
weak cold front will cross the waters late Tuesday night into
Wednesday, with SCA conditions possible.

Sub-SCA level winds are anticipated Wednesday through Friday.
Showers and possibly a brief thunderstorm will be possible over the
waters on Friday.

&&

.TIDES/COASTAL FLOODING...
Anomalies continue to fall as winds trend light. As a result,
coastal flooding in not expected as winds turn west
northwesterly through Monday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$
SYNOPSIS...BKF
NEAR TERM...BKF
SHORT TERM...BKF
LONG TERM...KJP
AVIATION...KJP
MARINE...KJP
TIDES/COASTAL FLOODING...BKF



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