Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 200800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Tue Jun 20 2017

.SYNOPSIS...Weak high pressure will build over the area today
and hold through Thursday. The next cold front will move across
the area at the end of the week or early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...Weak cdfnt is currently moving
through the area early this morning and is just west of the
I-95 corridor. The front will stall along the Atlantic coastline
and remain just south of Point Lookout through mid week before
it dissipates. There will be sufficient sfc and mid-level drying
and subtle height rises througout the day to prevent convection
from developing. There could be some patchy fog tonight but a
thin broken layer of mid-level clouds may inhibit fog formation.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...A shortwave-
trough moving around base of upper level trough over the Great
Lks will swing through the area during peak heating on Wed. This
may be enough to spark a few showers mainly across nrn and wrn
zones along the Pennsylvania border and along the spine of the
Appalachians. Have mainly slight to low chance PoPs over those
areas. Any shra activity will dissipate quickly with sunset.

Mid-level ridge then builds on Thu promoting a warming trend
with temps likely to climb into the low 90s. Moisture from the
Gulf and from Potential Tropical Cyclone 3 will advect
northward into the mid-Atlantic region Thu night into Fri. There
are notable differences between global models on timing of
moisture and thus showers reaching the area. Have slight to low
chance PoPs across the southwest part of the fcst area. Moisture
then gets entrained into a frontal system with risk of showers
increasing for the end of the week.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...

The end of the week into the weekend is still shaping up to be an
unsettled period as a frontal zone stalls out across the Mid-
Atlantic. Temperatures through this period may depend some on
clouds, precipitation, and frontal position, but overall should be
near to slightly above normal.

While the actual cold front will be north of the region
Friday, a prefrontal trough will be located east of the
Appalachians. At least some scattered showers and storms will be
possible. Instability isn`t progged to be very strong, but shear
profiles may increase with potential mid level jet streak.

Some uncertainty exists for Saturday into Sunday in terms of the
frontal position and what impact moisture (or even remnant low
pressure) of the current disturbance in the Gulf of Mexico will
have. Nevertheless, the environment will be characterized by high
precipitable water and weak instability, so some periods of heavier
rainfall are within the realm of possibility.

A second cold front will drop south in response to a deepening upper
trough over the Great Lakes, crossing the area sometime early next
week. Behind it, below normal temperatures and low humidity will
arrive.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...VFR conditions
through Thu night.

A slow moving cold front will result in the potential for showers
and thunderstorms Friday into Saturday.

&&

.MARINE...Winds generally below SCA through Thu night.

A cold front will approach from the northwest Friday and slip into
the area on Saturday. At a minimum this will result in a better
chance of thunderstorms. Southwest flow may approach SCA levels on
Friday. Wind forecast becomes more uncertain into Saturday depending
on strength of potential low pressure tracking along the front.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT early this morning for
     ANZ532>534-537-540-541-543.

&&

$$
SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...ADS
AVIATION...ADS/LFR
MARINE...BAJ/ADS/LFR



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