Martinsburg, West Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

171
FXUS61 KLWX 231455
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
955 AM EST Mon Dec 23 2024

.SYNOPSIS...
Strong Canadian high pressure builds in today with dry and very
cold conditions. A weak front will cross the area on Tuesday
bringing a chance of wintry precipitation. Another low pressure
system may approach late in the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Strong Canadian High pressure passing north of the area will
maintain dry and cold conditions. There will be plenty of
sunshine, though highs only reach the 30s (with upper 20s along
the MD/PA border and in the mountains). Cloud cover begins to
increase this afternoon into tonight as a weak cold front
approaches. Temperatures tonight will drop into the low to mid
20s across the area.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
A clipper system will pass by to the north, and that drags a weak
cold front south into our area from PA early Tuesday morning. The
high-res guidance has been much bolder with freezing precip
across our area, with the global guidance likely not resolving
the potential correctly. It is important to note that QPF
amounts are low, with only light precip expected. Still, the
model soundings indicate it is mostly, if not all, likely to be
freezing rain. Given the preceding days have been very cold, and
ambient temps will be in the 20s come Tuesday morning, any
freezing precip is expected to stick once it hits the ground. As
a result, Winter Weather Advisories have been issued for
portions of the Alleghenies, and generally along/north of
I-66/US-50 in northern VA/the eastern WV panhandle into
Maryland. There is uncertainty regarding the southern extent of
the current advisories.

Precipitation in the Alleghenies begins around 3-5 AM Tuesday
morning, and between 4-6 AM in the Potomac Highlands and along
the I-81 corridor from Winchester north. Precip begins
along/west of US-15 around 5-7 AM, and along the I-95 corridor
by sunrise (around 7 AM). Again, this is likely to be a light
freezing rain, with bridges, overpasses, and untreated roadways
and sidewalks becoming slick. Holiday travelers and commuters
should use extra caution and allow more time if driving through
the impacted areas Tuesday morning.

P-type is likely to be freezing rain at the onset. Some snow could
mix in along/north of I-70 and in the Alleghenies. By late morning,
some rain will mix east of the mountains as temps rise. Most of the
guidance has precipitation ending by early Tuesday afternoon, and
ending in the Alleghenies by early Tuesday evening.

Highs Tuesday reach the 40s, though remain around freezing along
and west of the Allegheny Front. Dry conditions Tuesday night
as lows drop to the upper 20s to low 30s.

Weak high pressure briefly passes through the region Wednesday
bringing dry and seasonable conditions. Expect abundant cloud
cover as a CAD wedge sets up in light northeast to east winds.
Highs in the low to mid 40s. A weakening mid-level trough
approaches the area from the TN Valley Wednesday night into
Thursday, though this system appears likely to wash out before
reaching the Mid-Atlantic. There is a small chance for some
wintry precip in the Alleghenies Wednesday night, but the recent
trend has been for less QPF with a slower progressing system.
Would not be surprised to see completely dry conditions through
Wednesday night as models come into better agreement.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A strong wedge of high pressure to our north will keep temperatures
near to slightly below average Thursday into Friday. Each day will
feature temperatures in the low 40s (30s in the mountains) and dry
conditions. Thursday will likely be cloudy for much of the area with
the CAD wedge in place. As high pressure lifts slowly northward on
Friday, this could start to break up a bit, bringing slightly warmer
temperatures and some peaks of sun. Thinking that most areas west of
I-95 should stay pretty socked in, but will have to continue to
watch model trends as we get closer. Models often struggle to nail
the timing of CAD events, and are often too quick to erode them. So,
sticking with that line of thinking in the latest forecast.

As we head into the weekend, the upper-level pattern becomes much
more unsettled as a very wavy pattern sets up across the CONUS.
Several upper shortwaves over the western CONUS will begin to make
their way east, with the first impacting us as early as Saturday.
The aforementioned strong area of high pressure looks to still be
locked in to our north Saturday, which could provide a continued
source of cold air. Highs are currently forecast in the mid to upper
40s that day as this high retreats. However, could see some cold air
being locked in during the morning hours on Saturday. If any
precipitation were to begin during that timeframe, it could be
wintry in nature, especially west of the Blue Ridge. For now, PoPs
are too low for that, but there is a lot of uncertainty in that
part of the forecast given how many different upper-level
features are at play.

Meanwhile, during this same timeframe, the primary upper trough axis
is located over the southern Plains which will develop an area of low
pressure as it moves into the Mississippi River Valley into Saturday
evening. This system will deepen rather quickly into Sunday and
likely move into the Great Lakes region. We should see a warmup in
response to this system as winds turn southerly ahead of it. Rain is
expected for much of the area with this system, but the question
will be: how much? This level of detail will come in future
iterations of the forecast, but for now it is just something to
watch moving forward.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
VFR conditions are expected through late this evening. A weak cold
front moves into the area Tuesday morning and brings a mix of
rain and freezing rain to MRB, IAD, DCA, BWI, and MTN. This
looks to be most likely between 09Z to 15Z Tuesday, then any
lingering precip into early Tuesday afternoon becomes a cold
rain. Dry conditions return Tuesday evening. Remaining VFR
through Wednesday night.

Sub-VFR conditions are possible on both Thursday and Friday as a CAD
wedge sets up with strong high pressure to our north. Thinking most
should remain MVFR during this time.

&&

.MARINE...
Marine conditions are expected to be generally favorable through the
middle of this week. High pressure slides off the coast, then an
area of low pressure brings a chance of wintry precipitation Tuesday
morning. A period of southerly channeling is possible this evening
into tonight, with a few wind gusts in the 15-20 knot range. Did not
issue an SCA at this time due to low confidence, and sporadic nature
of any higher gusts. A Marine Weather Statement would best cover
these elevated winds.

A light N/NE wind is expected on Thursday into Friday as a CAD
wedge sets up with strong high pressure to the north. No marine
hazards are expected during this time.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Winter Weather Advisory from 5 AM to 1 PM EST Tuesday for
     DCZ001.
MD...Winter Weather Advisory from 5 AM to 1 PM EST Tuesday for
     MDZ004>006-008-011-013-014-503>508.
     Winter Weather Advisory from 4 AM to 7 PM EST Tuesday for
     MDZ001-501.
     Winter Weather Advisory from 5 AM to 10 AM EST Tuesday for
     MDZ003.
VA...Winter Weather Advisory from 5 AM to 1 PM EST Tuesday for
     VAZ053-054-501-505-506-526-527.
     Winter Weather Advisory from 5 AM to 10 AM EST Tuesday for
     VAZ028-030-031.
WV...Winter Weather Advisory from 4 AM to 7 PM EST Tuesday for
     WVZ501-503-505.
     Winter Weather Advisory from 5 AM to 10 AM EST Tuesday for
     WVZ051>053.
MARINE...Winter Weather Advisory from 5 AM to 1 PM EST Tuesday for
     ANZ530.

&&

$$

SYNOPSIS...KRR
NEAR TERM...DHOF/KRR
SHORT TERM...KRR
LONG TERM...CJL
AVIATION...DHOF/CJL/KRR
MARINE...DHOF/CJL/KRR