Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 140155
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
855 PM EST Mon Nov 13 2017

.SYNOPSIS...
High pressure will return tonight through Wednesday.
A weak cold front will cross the area Wednesday night into
Thursday morning with high pressure moving back in for Friday.
A stronger cold front will cross the area Saturday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
High pressure will build over the area tonight. A northerly flow
around the building high will cause seasonably chilly
conditions...but it will remain dry. A thin deck of stratus
clouds are expected...especially west of the Blue Ridge
Mountains through late this evening. Breaks in the clouds and
low temp/dewpoint depressions may lead to patchy fog late this
evening and overnight. Fog may be locally dense...but a light
northerly flow should prevent widespread fog from developing.

A light upslope flow will cause areas of drizzle along and west
of the Allegheny Front this evening. Temps will drop below
freezing overnight across these areas. Somewhat drier air may
cause drizzle to dissipate or become less widespread
overnight...but any wet areas will have the potential to freeze
late tonight with temps dropping below freezing.

Lows tonight will range from the upper 20s and lower 30s along
the Allegheny Front...to the mid and upper 30s across most other
locations...to near 40 in downtown Washington and Baltimore.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
High pressure will hold over the area Tue into Wed. A weak cold
front will cross the area late Wed night into Thu morning
bringing sct showers as far east as the Rt 15 corridor.
Temperatures will continue to warm a bit more into the mid 50s
Tue and Wed.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Relatively active pattern expected for the latter part of this week
and into the weekend with the most impactful weather likely to be
Saturday.

Weak cold front anticipated to be passing through the area early
Thursday morning with the potential for a few rain showers, but the
majority of the day should end up dry. This will be followed by high
pressure and calm weather for Thursday night and Friday.
Temperatures should be within a few degrees of climatological
normals Thursday/Friday.

A potent low pressure system is then projected to move through the
Great Lakes region Friday night into Saturday. This will bring
strong southwest flow to the area out ahead of the front before the
attendant cold front sweeps across the region sometime during the
day, although model differences still exist on timing of frontal
passage. This will bring increased chances of rain and gusty winds,
in addition to a non-zero threat of convective activity.
Temperatures will be near to somewhat above climo normals ahead of
the front.

Following the frontal passage, there will be gusty west to northwest
flow with colder temperatures and the potential for upslope snow
showers along the Allegheny Front and nearby higher elevations
Sunday and Sunday night.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
VFR conditions are most likely through tonight. Patchy fog is
possible and this may cause reduced vsbys overnight. Confidence
too low to put into TAFS at this time since a light northerly
flow is causing dewpoints to slowly drop.

Primarily VFR expected Thursday through Friday night as high
pressure builds into the area. Potential then exists for sub-VFR
conditions and gusty winds/low level wind shear Saturday as a strong
cold frontal system crosses the region.

&&

.MARINE...
Northerly winds are expected along the waters tonight. An SCA is
in effect for most of the Bay and lower Tidal Potomac through
this evening...then for the middle portion of the Bay overnight.
Winds may come close to SCA levels over the Bay and lower Tidal
Potomac River Tuesday...but confidence is too low for an
advisory at this time.

Winds will diminish Wed and Wed night.

SCA gusts likely behind a departing cold front Thursday into
Thursday evening before high pressure brings lighter winds later
Thursday night and Friday. Winds will increase markedly with an
approaching frontal system Friday night and Saturday with SCA likely
and gale possible.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for
     ANZ531>533-537-539>541.
     Small Craft Advisory until 11 AM EST Tuesday for ANZ534-543.

&&

$$
SYNOPSIS...LFR
NEAR TERM...BJL/LFR
SHORT TERM...LFR
LONG TERM...MM
AVIATION...BJL/MM/LFR
MARINE...BJL/MM/LFR



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