204
FXUS61 KLWX 140207
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
907 PM EST Sat Dec 13 2025
.SYNOPSIS...
An Arctic front bring a blast of snow and bitter cold
temperatures to the area late tonight into Sunday. Accumulating
snow will push into the mountains this afternoon before
spreading east later this evening and into the overnight hours.
Gusty winds behind the front will lead to plunging temperatures
with wind chills values expected in the teens and single digits
late Sunday afternoon. Arctic high pressure settles over the
region Monday before shifting offshore Tuesday. This will yield
a pattern change with warming temperatures heading into the
middle and end of next week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
No major changes to the previous forecast. Added western
Loudoun to the Winter Weather Advisory earlier this evening.
This is a banding type set up with favorable conditions for CSI
banding. Given that, some areas will overperform and some will
underperform, just the nature of banding. Snow has been the
p-type observed at onset across most of MD thus far. Further
south, rain may mix in at onset. Currently evaluating guidance
to see if any potential extensions are necessary in the
advisory further south into Prince William or Fredericksburg.
Just not enough confidence at this time. Also, areas in NE MD
near the PA State Line may approach warning criteria. Just
something to keep an eye on. Previous discussion follows...
Winter Storm Warnings remain in effect for western Garrett and
western Grant counties, where 4-8 inches of snow is expected.
Localized higher totals are possible over western favored slopes
given ratios hovering between 17:1 and 21:1 late tonight into
Sunday morning. Winter Weather Advisories remain in effect for
eastern Garrett, western Allegany, and western Pendleton
Counties, where 2-4 inches of snow is expected.
Snow will gradually spread east during the late evening and
overnight period as the open wave of energy ejects eastward into the
region. Most models continue to show 100+ kt jet steak developing
downstream, with forcing for ascent increasing within the
equatorward entrance of the jet streak. Most solutions show the jet
entrance region lining up right along I-95. Ascent within the jet
entrance region may cause precipitation to jump eastward and develop
in-situ along the I-95 corridor, largely skipping locations between
the Allegheny Front and Blue Ridge.
The precipitation may begin as a brief period of rain or mixed rain
and snow, especially along and southeast of the I-95 corridor. This
mix should be short-lived, however, as much colder air rushes in
behind an Arctic front that will move through over the course of the
night. In terms of timing, some light precipitation could begin as
early as the mid-late evening hours 7-11pm, but the bulk of the
precipitation along the I-95 corridor is expected to occur between
roughly 11 PM and 6 AM.
The band that will develop will be a relatively narrow with moderate
to heavy snow at times. Snowfall rates within the band could near or
potentially briefly exceed one inch per hour at times late
tonight(for a 3-6 hr time window). With a narrow feature
producing heavy precipitation, snow totals will be heavily
dependent on the ultimate placement of this band. This, combined
with the potential for a bit of mixing with rain at onset makes
for a challenging snowfall forecast. Latest guidance shows a
northward progression of the band with the highest confidence
for 3"+ totals generally from Baltimore points north and east
into southern NJ.
Expecting 1-3 inches for most with some higher totals closer to 4-6
inches in far northeast MD (northern Baltimore, Harford, and Cecil
counties). There is also a potential for some over northern
Frederick and Carroll counties with 3 to 5 inches from the
Catoctins east toward Parr`s Ridge. Winter Weather Advisories
will continue for these areas from later this evening through
early Sunday morning.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Fast moving low pressure and it`s associated Arctic cold frontal
boundary will exit the area Sunday with a strong dome of Canadian
high pressure building in. This will allow for bitterly cold
conditions Sunday afternoon through Monday night. Temperatures look
to rebound as the Arctic high shifts offshore Tuesday into Wednesday
next week.
Snow will end from northwest to southeast a few hours either side of
daybreak, with the back edge of the snow clearing southern Maryland
by around mid- morning. Residual upslope snow showers will likely
linger over the mountains through Sunday night given predominant
west to northwest flow. Meanwhile, 1036-1042 mb Arctic/Canadian high
pressure over the upper Midwest will build eastward. The tightened
gradient between the departing Arctic cold front and building Arctic
surface high will lead to brisk and blustery conditions Sunday
afternoon/evening. Wind gusts of 30-40 mph are possible with locally
higher gusts over the ridges/waters. This will yield to a
combination of plummeting temperatures (850 mb temps -15 to -20
degrees C) and wind chills throughout Sunday into Monday as winds
remain elevated. Overall looking at a non-diurnal temperatures
spread Sunday with high temperatures likely occurring close to
midnight and falling into the mid to upper 20s (single digits and
teens mountains) throughout the day. Lows Sunday night will range
from near 0 over the mountains to the mid and upper teens east of
the Blue Ridge/I-95 metros. These values are 5 to 15 degrees above
record territory for this time of year. Wind chill values will drop
into the single digits and low teens east of the mountains Sunday
afternoon with near 0 to subzero values over the mountains. Wind
chills could drop as low as -20 to -30 degrees for a period of time
over the highest elevations above 3000 feet late Sunday night into
Monday morning. Cold Weather Advisories are in effect for the
mountains and portions of the Shenandoah Valley Sunday afternoon
into Monday morning for values as low as -10 degrees. These
advisories may need to be expanded further east with wind
chills likely to approach 0 especially over northern MD and
central Shenandoah Valley.
Cold high pressure settles overhead Monday into Monday night
allowing the winds to gradually settle down. Gusts of 15 to 25 mph
can be expected through the afternoon with highs for most struggling
to make freezing. Mountain locations will remain in the mid to upper
teens throughout the day. The added wind will keep wind chills in
the single digits over the mountains with low to mid 20s elsewhere
across the region. Lows Monday night will fall into the mid to upper
teens and low 20s under clear skies.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
After a cold start Tuesday, temperatures will rebound to the
upper 30s as Arctic high pressure shifts offshore and winds turn
southerly. Fair weather and much warmer Wed and Thu under
increasing southerly flow.
Powerful low pressure north of the western Great Lks Thu will push a
strong cold front through the area Thu night. There will be a chance
of rain and mountain snow showers with this system. Very strong low-
level fields are progged with this front with 850 mb winds in excess
of 70 kt and 925 mb winds over 55 kt pose some concern for damaging
winds. High pressure builds for the end of the week bringing quieter
weather.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Lower ceilings and snow are expected to develop across much of
the forecast area, starting as early as this evening. BWI, MTN,
DCA, and IAD are most likely to experience the greatest impacts
from snow, with a couple inches of accumulation possible during
the second half of the night. The precipitation could also
briefly mix with rain at onset. Chances for snowfall are a bit
lesser at MRB, but would be on the earlier side of things,
starting as early as 01-03z tonight. But accumulations look to
be very minimal if they occur at all at MRB. Snow appears as
though it will likely avoid CHO altogether, though can`t rule
out a few flurries overnight into early Sunday between 08- 11z.
The main impact at the corridor terminals looks to occur with a
thump of snow between 05-11z. This is when the steadiest snow
and greatest reductions to visibility look to occur. Expect
vsbys between 1/2-2SM at BWI/IAD/DCA with accumulations of 1-3
inches expected. 2-4 inch amounts are of greater confidence at
BWI/MTN points north and east toward PHI.
Some temporary sub-VFR reductions are expected to linger early
Sunday morning as low pressure departs the region. Any snow
will wrap up within the I-95 corridor early Sunday morning with
VFR conditions returning Sunday afternoon. Wind will be the
bigger issue for aviators with gusts hovering between 25 to 35
kts. This is especially true at terminals near the waters and
ridges as there will be a stout pressure gradient between the
departing front and incoming cold high pressure system. Breezy
conditions continue through Monday afternoon with winds (gusts
15 to 25 kts) trending downward Tuesday. VFR conditions are
expected both days.
VFR conditions Tuesday and Wednesday as high pressure moves overhead
and eventually offshore. Winds light and variable Tuesday as the
high is overhead, but will turn out of the southwest Tuesday night
into Wednesday, albeit remaining light. No precipitation is expected.
&&
.MARINE...
Winds will turn out of the northwest and pick up fairly rapidly
in magnitude during late tonight as an Arctic front moves over
the waters.Gale Warnings have been hoisted with the overnight
forecast package to cover this threat. However, the peak winds
may not occur until mid-late morning. Still, conditions will
deteriorate quickly around daybreak. Freezing spray may also be
possible at times during the day Sunday and into Sunday night,
especially over the wider waters of the Chesapeake Bay, where
waves may be up to 6 feet at times and winds remain Gale-force.
Gale conditions gradually taper off overnight from northwest to
southeast, but will linger over the lower Tidal Potomac and
middle Bay until early Monday morning. Winds drop below sub-SCA
levels Monday evening into Tuesday.
SCA conditions expected to continue Monday with gusts up to 25 kt,
diminishing gradually through the day and night, and dropping below
SCA threshold by daybreak Tuesday. Possible SCA conditions Tue night
in southerly flow, but more likely Thu night.
&&
.TIDES/COASTAL FLOODING...
Following the passage of a strong arctic cold front Sunday,
gusty northwest winds will push water south and towards the
southern portions of the Chesapeake Bay fairly rapidly. Blowout
tides seem likely for many areas along the western shoreline of
the Chesapeake Bay by the Sunday evening low tide cycle and
continuing into Monday as well.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Winter Weather Advisory from midnight tonight to 10 AM EST
Sunday for DCZ001.
MD...Winter Weather Advisory from midnight tonight to 10 AM EST
Sunday for MDZ008-011-013-014-016-018-503>506-508.
Gale Warning from 6 AM to 6 PM EST Sunday for MDZ008.
Small Craft Advisory from 6 PM Sunday to 6 AM EST Monday for
MDZ008.
Winter Weather Advisory until 7 AM EST Sunday for MDZ004>006-
507.
Winter Weather Advisory until 1 PM EST Sunday for MDZ501-510.
Cold Weather Advisory from 1 PM Sunday to 1 AM EST Monday for
MDZ501.
Winter Storm Warning until 4 PM EST Sunday for MDZ509.
Cold Weather Advisory from 7 AM Sunday to 10 AM EST Monday for
MDZ509-510.
VA...Winter Weather Advisory from midnight tonight to 10 AM EST
Sunday for VAZ053-054-505-506.
Cold Weather Advisory from 1 PM Sunday to 1 AM EST Monday for
VAZ504-507-508.
Cold Weather Advisory from 7 AM Sunday to 10 AM EST Monday for
VAZ503.
Cold Weather Advisory from 4 PM Sunday to 1 AM EST Monday for
VAZ025-026.
WV...Winter Weather Advisory until 1 PM EST Sunday for WVZ503-505.
Cold Weather Advisory from 1 PM Sunday to 1 AM EST Monday for
WVZ503-506.
Winter Storm Warning until 4 PM EST Sunday for WVZ501.
Cold Weather Advisory from 7 AM Sunday to 10 AM EST Monday for
WVZ501-505.
MARINE...Winter Weather Advisory from midnight tonight to 10 AM EST
Sunday for ANZ530.
Gale Warning from 6 AM to 6 PM EST Sunday for ANZ530-531-535-
536-538-539.
Small Craft Advisory from 6 PM Sunday to 6 AM EST Monday for
ANZ530-531-535-536-538-539.
Gale Warning from 6 AM Sunday to 6 AM EST Monday for
ANZ532>534-537-540>543.
&&
$$
SYNOPSIS...EST
NEAR TERM...CPB/EST
SHORT TERM...EST
LONG TERM...LFR
AVIATION...LFR/CJL/CPB/EST
MARINE...LFR/CJL/CPB/EST
TIDES/COASTAL FLOODING...LWX
NWS LWX Office Area Forecast Discussion