101
FXUS61 KLWX 310904
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
404 AM EST Fri Jan 31 2025

.SYNOPSIS...
A low pressure system will cross from west to east across the
area today, with the trailing cold front pushing through by
early Saturday morning. High pressure will build into the area
Saturday before departing to the east Sunday. As low pressure
passes to the north, a warm front will lift through the area by
Monday morning, followed by a cold front Monday night. Another
low pressure system may approach toward the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Low pressure is located over northern Missouri this morning and
will eventually track across Pennsylvania late this afternoon
and evening. Rain on the warm advection side of this system is
spreading into the area this morning. While everyone will
eventually see rain, it may be lighter and more spotty across
the northern half of the area until midday or this afternoon. At
the same time, the southern half of the area may see some breaks
in the rain this afternoon as a dry slot lifts north. A trailing
conveyor belt of moisture will then sweep across the area during
the late afternoon and evening, with rain exiting southern
Maryland during the second half of the night. Total rainfall
will generally range between 0.50-1 inch. The greatest chance
for more than an inch will be across the southern half of the
area and west of the Allegheny Front. Rain totals have trended
down a bit in the north, so some locations near the Pennsylvania
border may not reach a half inch. There remains some concern for
flooding along and west of the Allegheny Front where this rain
will be falling on a deep snow pack. A Flood Watch remains in
effect for this area.

There remains a signal for a brief surge in winds as the dry
slot works north into the area late this morning into the early
afternoon. Think model wind gust output is generally overdone
due to stable low levels, but a few 20-30 mph gusts aren`t out
of the question.

Temperature rises will be muted today, with highs in the upper
40s and 50s expected. The cold front with this system won`t push
through until late tonight, so temperatures will only drop into
the mid 30s to mid 40s by dawn. West of the Allegheny Front,
there will be another period of brief orographic enhanced
precipitation during the second half of the night as the colder
air moves in. The moisture isn`t particularly deep, but
precipitation could end as a brief period of snow or freezing
drizzle with little to no accumulation.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
In the wake of the cold front Saturday morning, northwest winds
will increase sharply, with 20-30 mph gusts possible. The front
may also be accompanied by a band of clouds, but these should
clear out by midday, and gusts should start decreasing in the
afternoon. High temperatures will remain a little above normal
in the 40s and lower 50s. As the high slides to the north
Saturday night, low temperatures will drop into the 20s.

The high will be over New England by Sunday morning, resulting
in onshore surface flow. Meanwhile southwesterly winds aloft
will cause warm advection to occur. Precipitation appears
unlikely, but clouds will thicken. Can`t totally rule out some
freezing drizzle on the eastern slopes of the Alleghenies Sunday
morning, although models like the NAM tend to be oversaturated
in cases like this. Have forecast high temperatures in the 40s,
but this will depend on the thickness of the cloud cover. The
high will progress eastward Sunday night as low pressure moves
north of the Great Lakes. Lows could occur during the evening
with nearly steady or locally rising temperatures overnight.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Quasi-zonal flow off the Pacific Ocean will bring above normal
temperatures for much of the long term. Monday will be mild and dry
with highs in the upper 50s to low 60s areawide (40s mtns). As
a moisture starved cold front moves through Monday night (a few
high elevation rain or snow showers are possible in the
Alleghenies), temperatures will fall back into the upper 40s to
50s Tuesday. Similar story Wednesday with continued dry
conditions. The aforementioned cold front stalls in the
southeast U.S. Tuesday into Wednesday before returning north as
a warm front Thursday. If this front makes it north of the
region (which most guidance does), Thursday will likely be the
warmest day of 2025 thus far (mid to upper 60s are possible,
cannot rule out a 70 in central VA at this time given anomalous
H85 temps. This is not long lived as an approaching trough
brings a cold front Thursday night into Friday which should
bring the next chance for widespread rainfall (could end as snow
in the Alleghenies).

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
Some waves of light rain are spreading across the area, although
sub-VFR conditions are lagging well to the southwest. The latest
guidance suggests a drop to IFR during the mid to late morning.
The heaviest rain will be across CHO this morning before lifting
toward the metro areas during the late morning and afternoon,
at which time a dry slot will work north. This could lead to an
increase in ceilings and a break in the rain, especially from
DCA/IAD to the south. Around the same time, some briefly higher
winds may attempt to mix down. Think raw model wind gust output
is overdone, but there could be a 1-2 hour period of 20-30 kt
gusts. For now, have a broad-brushed 20 kt in the TAF until this
becomes more certain. LLWS will also be possible at times
through this afternoon, although it is admittedly marginal and
will depend on the sharpness of low level temperature profiles.

The initial shift to westerly winds late this evening/around
midnight will lead to drying conditions and lifting ceilings.
The primary cold front will drop through around dawn Saturday,
resulting in a wind shift to the northwest and gusts around
20-25 kt. There may also be a band of MVFR ceilings in the
vicinity of the front, but these will clear out by midday
Saturday. Gusts gradually diminish during the afternoon as high
pressure builds to the north.

Sub-VFR ceilings are possible Sunday as a warm front lifts toward
the area. Also will see some gusty southerly winds up to 20
knots, especially at CHO.

VFR conditions should return Monday and Tuesday. Expect relatively
light SW winds Monday, turning NW by Tuesday. Winds will only
be around 10 to 15 knots during this time.

&&

.MARINE...
Southerly winds are expected through today. Warming air above
cold water will likely limit mixing, and that draws into
question the extent of gusts that are able to mix to the
surface. Still, at least periods of SCA level gusts are likely
with Small Craft Advisories in effect for a majority of the
waters through 6 PM. Most gusts will be around 20 kt, but a few
to 25 kt could occur as a dry slot moves in. Rain and fog will
also reduce visibility.

Winds will diminish this evening and shift to the west
overnight. The primary cold front will move through around dawn
Saturday, with a surge of northwesterly winds up to 25 kt. Small
Craft Advisories will likely be needed Saturday before winds
diminish by the evening as high pressure moves to the north.

Easterly flow on Sunday will gradually become southerly Sunday
night as a warm front lifts through. Sub-advisory conditions are
forecast at this time, but it may be close.

Southwest winds Monday will become northwest by Tuesday as a
cold front passes.

&&

.HYDROLOGY...
Flood Watches are in place along much of the Allegheny Front
through today. The current snowpack across this region consists
of 2 to 5 inches of liquid equivalent. With forecast rainfall
amounts around 1 to 2 inches, perhaps nearing 3 inches locally
across western portions of Highland and Pendleton counties, some
areas of flooding are possible given the added element of snow
melt.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory from noon today to 6 PM EST this evening
     for MDZ008.
     Flood Watch through this afternoon for MDZ001.
VA...Flood Watch through this evening for VAZ503.
WV...Flood Watch through this afternoon for WVZ501.
     Flood Watch through this evening for WVZ505.
MARINE...Small Craft Advisory from noon today to 6 PM EST this evening
     for ANZ530-531-538-539.
     Small Craft Advisory from 8 AM this morning to 6 PM EST this
     evening for ANZ532>537-540>543.

&&

$$

SYNOPSIS...ADS
NEAR TERM...ADS
SHORT TERM...ADS
LONG TERM...CPB
AVIATION...ADS/CPB
MARINE...ADS/CPB
HYDROLOGY...LWX