Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 170759
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
359 AM EDT Wed Oct 17 2018

.SYNOPSIS...A cold front will cross the area late today.
High pressure will build over the area tonight through Thursday
night and then move offshore Friday. Another cold front will
pass through Saturday and high pressure will build overhead for
early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...

Light rain over St. Marys County will exit by daybreak with
clouds thining out and skies becoming clear by midday. A mild
afternoon is expected with highs in the low to mid 60s, a few
degs higher than yesterday. A dry cold front will then cross
the area late in the afternoon and bring coolest air of the
fall season so far. Lows tonight will be in the 40s east of the
Blue Ridge with sub-freezing temperatures expected over the
higher elevations as h85 temps drop to -6C. It will become windy
late this afternoon and evening with gusts up to 30 mph with
frontal passage with a gradual decrease in winds overnight.
Freeze Warning was issued for the higher elevs.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...

High pressure will gradually build from the west Thu with
pressure gradient relaxing and winds diminishing somewhat. Still
breezy with gusts to 25 mph and with temperatures only rising
into the low to mid 50s. Chilly Thu night with diminishing
winds. Lows in the mid to upper 30s and below freezing west of
the Blue Ridge. Additional frost advisories and freeze warnings
will be required.

Warmer Fri as high pressure shifts offshore and winds turn
southerly. Showers are expected Fri night ahead of another
cold front.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...

Cool autumnal weather will be featured for the weekend and into
early next week with temperatures skewing below normal.

A low pressure system will be moving well north of the region
through Canada on Saturday, with its attendant cold front crossing
through the area during the day. Rain shower chances will linger
into Saturday morning before drying west to northwest flow then
takes over by the afternoon and evening. While this will dry most
locations out, it will help keep upslope rain showers going along
the Allegheny Front. Breezy conditions are expected for the second
half of the day with highs in the 60s. A potent upper level trough
will then move through Saturday evening and Saturday night as a
secondary cold front pushes across the area. This will keep upslope
precipitation going through the night, changing some of that over to
snow showers across the higher elevations. Elsewhere, dry and
blustery conditions expected Saturday night with lows in the 40s.

Northwest flow will then dominate for Sunday behind the departing
system before high pressure returns for Sunday night and Monday. Dry
and cool conditions are expected, with temperatures about 10-12
degrees below normals, highs in the 50s and lows in the 20s and 30s.
Warm air advection will begin later Monday and Monday night as a
clipper system dives north of the area Tuesday. This will promote
moderating temperatures with highs on Tuesday in the 50s/60s.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...

Gusty W winds developing later today becoming NW late with fropa with
gusts up to 25 kt. Winds diminish somewhat Thu with gusts up to
20 kt.

There is potential for sub-VFR conditions Saturday morning as a
system moves through with chances for rain showers. VFR will return
Saturday afternoon through Sunday with developing gusty west to
northwest winds.

&&

.MARINE...

SCA conditions developing later this morning, then winds
increase up to 30 kt this evening and continue through the
night. SCA conditions will persist through Thu. Winds drop below
SCA Thu night and increase again Fri night.

SCA conditions are probable Saturday, Saturday night, and Sunday as
west to northwest winds increase behind a departing system and
strong cold front.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...Freeze Warning from midnight tonight to 11 AM EDT Thursday for
     VAZ503-504.
WV...Freeze Warning from midnight tonight to 11 AM EDT Thursday for
     WVZ501-505-506.
MARINE...Small Craft Advisory from 11 AM this morning to 6 PM EDT
     Thursday for ANZ530>534-537>543.
     Small Craft Advisory from 11 AM this morning to 6 AM EDT
     Thursday for ANZ535-536.
     Small Craft Advisory from 10 AM to 6 PM EDT Thursday for
     ANZ535-536.

&&

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


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