Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KLWX 240757
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
357 AM EDT Wed Apr 24 2019

.SYNOPSIS...
A cold front will stall across southside Virginia or northern
North Carolina today. The front will return as a warm front
Thursday before a low pressure system tracks across the Ohio
Valley toward the northeastern United States. A second cold
front, attached to the low pressure system, will approach
Friday. High pressure will build in behind this front for the
early part of the weekend. Another storm system could approach
the region during the second half of the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
A weak cold front approaching the Interstate 95 corridor as well
as the Central Virginia Foothills early this morning. The widely
scattered showers/thunderstorms that marked this boundary
dissipated after midnight. All that is left are the clouds,
which are quite extensive across the forecast area. Believe that
the cloud cover will scatter out before noontime, especially
along and northeast of the Potomac River Valley. Breaks evident
in the clouds across eastern Pennsylvania at this time.

The cold front will settle across southside Virginia or northern
North Carolina this afternoon/evening, which should result in
partly cloudy and dry conditions. However, return flow will
commence later tonight, resulting in an increase in cloud cover
once again. There could be enough upglide, coupled with a weak
shortwave, for showers to develop west of the Blue Ridge after
midnight. Will maintain PoPs no higher than chance.

Although cold advection will be strong this morning, that`s
likely to be offset by compressional warning and a flattening of
mid-level flow in the wake of upper level low pressure exiting
New England. Thus, highs in the mid-upper 70s still likely
across a fair portion of the forecast area. Lows will be lower
than this morning, especially across northern Maryland.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
A weak shortwave passage early Thursday will support scattered
to perhaps numerous showers as upglide from the advancing warm
front overspreads the region. While clouds may be plentiful
Thursday afternoon-evening, it appears as though there may be a
break in forcing mechanisms.

Thursday night into Friday morning, heights drop as a trough
axis/surface cold front cross the area. Shear and moisture will
both be available in abundance. Minimal instability may be able
to develop as well. Will maintain slight chance/chance thunder
in forecast, primarily in advance of the trough axis.

Guidance suggests that wind fields increase in the wake of this
front...mainly for Friday night. Momentum transfer should be
favorable.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Cooler and windy (gusts up to 30 mph) Saturday in the wake of
deepening low pressure area over Downeast Maine. Weak high pressure
returns for Saturday night before a weak cold front crosses the area
Sunday afternoon. Not much in the way of moisture or instability
available with this front, so the risk of showers appears isolated
at best. Better convective potential appears possible right at the
end of the month and the first few days in May as a sfc front
becomes stationary near the area and multiple waves of low pressure
ride along the front. High degree of uncertainty here with exact
position of sfc front and thus temperatures and precip timing, but
time of the year favors back door fronts to push farther south than
models suggest.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
VFR flight conditions will prevail today-tonight. Northwest
winds will increase this morning in the wake of a dry cold
frontal passage. Based on MTRs, it appears as though that has
already begun at MRB. Anticipate 20-25 kt gusts for most of the
day.

Showers will affect the terminals Thursday, with perhaps a brief
break Thursday afternoon or early evening, before more showers
arrive Thursday night. A cold front will support additional
showers, with perhaps heavy rain and gusty winds Friday. Would
not rule out a thunderstorm on Friday either.

Flight restrictions plausible Thursday night into Friday.
NW winds will gust to around 25 kt Sat before diminishing to 10 kt
or less Sat night.

&&

.MARINE...
Southerly channeling attempted to develop early this morning,
but it was impeded by clouds and an advancing cold front. Still
have a Marine Statement in effect for the mid Bay/lower Potomac
for a stray 18-20 kt gust.

The cold front will cross the waters this morning. Expect
northwest winds to increase in the wake of this frontal
passage. A Small Craft Advisory in effect for most of the Bay
and upper tidal Potomac today. That forecast still looks valid,
although suspect most of the qualifying gusts will be nearshore.

Conditions will be quieter tonight into Thursday as the front
settles south of the Bay and then slowly marks its return.
Showers will affect the waters Thursday into Friday. A cold
front will be the triggering mechanism on Friday; a couple of
thunderstorms will be possible at that time. Would not rule out
associated gusty winds (Marine Warnings). Gradient winds will
increase in the wake of the front Friday night; high confidence
in Small Craft Advisories.

High end SCA conditions expected Saturday with an outside chance of
gale conditions (1 in 10 chance) before winds diminish Sat night to
10 kt or less.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 8 AM this morning to 6 PM EDT this
     evening for ANZ530>533-535-538>541.

&&

$$
SYNOPSIS...HTS
NEAR TERM...HTS
SHORT TERM...HTS
LONG TERM...LFR
AVIATION...HTS/LFR
MARINE...HTS/LFR


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.