Martinsburg, West Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

538
FXUS61 KLWX 140220
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
920 PM EST Wed Nov 13 2024

.SYNOPSIS...
Precipitation chances will return with a cold front Thursday
into Friday. The front could bring light wintry precipitation to
parts of the Alleghenies Thursday morning. Dry conditions and
moderating temperatures are expected this weekend into early
next week as high pressure returns to the area.

&&

.NEAR TERM /UNTIL 8 AM THURSDAY MORNING/...
The precipitable water value on the 00Z IAD sounding was only
0.20 inches, with even lower values at PIT and RNK. The
necessary saturation processes support the idea that precip
onset will be on the slower side, possibly after 8 or 9 AM in
our southwestern zones. While trends will need to be monitored
in the data sparse Alleghenies, latest guidance continues to
support the idea that any wintry precipitation will be limited
in area and impact.

Otherwise, will be making some small adjustments to temperatures
as values quickly crashed toward the low dew points this
evening. Mid and high level clouds will be on the increase
through the night.

Previous discussion:

As for precipitation chances, latest guidance continues to
trend a bit later due to the very dry air in place.
Precipitation looks to move into the Alleghenies and Shenandaoh
Valley Thursday morning before gradually pushing eastward. A
light wintry mix remains possible over the high/sheltered
valleys of the Alleghenies. Temperatures at onset in these
locations will sit between 29 and 34 degrees. The highest
confidence for a mix of snow, sleet, and freezing rain will be
across western Grant/Pendleton/Highland Counties. These
locations look to hold onto the coldest air the longest due to
light flow just below the ridgeline. Any impacts will be limited
to elevated surfaces with precipitation intensity remaining
light. Given the very dry surface air ahead of the system, warm
road temps, and marginal air temperatures, have held off on
Winter Weather Advisories at this time. A Special Weather
Statement for slick spots during the Thursday morning commute
may be issued, but the threat looks marginal/isolated. Continue
to monitor the situation as trends could change. Lows tonight
will range from the upper 20s in the sheltered valleys with low
to mid 30s elsewhere across the region. Northern and central MD
may end up in the upper 20s as they look to radiate a bit better
compared to other locations due to the slow progression of the
cloud shield northward with an ample dry airmass in place.

&&

.SHORT TERM /8 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
We are looking at some beneficial rainfall to help with the
drought and fire weather concerns for the second half of the
workweek. The upper-level trough will continue to eject toward
the eastern Great Lakes with the attendant cold front expected
to cross the Mid-Atlantic late Thursday into Friday. Decent
moisture advection and ascent/forcing will occur ahead of the
system Thursday morning into Thursday afternoon. Antecedent
conditions look dry with high pressure wedged in from the north
potentially delaying the onset of precipitation in many
locations along and east of I-81 toward after the Thursday
morning rush. Locations further west (especially the
high/sheltered valleys of the Alleghenies) may start with a
brief wintry mix before transitioning to rain due to light east
to southeast winds setting up a weak CAD wedge in these
locations prior to precipitation arrival. Any wintry precip
accumulation is expected to be light, only a few hundredths of
an inch, and be mainly on elevated surfaces.

Elsewhere, a chilly rain is expected with highs ranging from
the mid to upper 40s east of the Alleghenies to low 50s along
and east of the I-95 corridor. Shower coverage and intensity
will pick up Thursday morning into Thursday afternoon. The
steadiest rain (at least moderate intensity) should arrive
Thursday afternoon and Thursday night. Rain amounts around a
quarter to half an inch are expected across the area. Locally
heavier totals are possible over the central Shenandoah Valley
and Allegheny Highlands. There is some uncertainty in rainfall
mounts near the Potomac River as dry air associated with high
pressure to the northeast will be more stubborn the further
north and east one goes. Lows Thursday night will settle in the
mid 30s to low 40s.

By Friday, some lingering early/mid morning showers are possible for
those along and east of I-95. Any activity could end earlier if the
parent system trends quicker. A mixture of clouds and sun is
expected with high temperatures in the mid/upper 50s (40s to low
50s for mountain locations). Some light precipitation may
continue across the Allegheny Front and higher elevations
heading into Saturday. Lows Friday night will fall into the
upper 30s and lower 40s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
High pressure will provide dry conditions and seasonable
temperatures Saturday through Sunday. Highs will be in the lower
60s both days. Low temperatures each night will be in the upper
30s to lower 40s.

A weak, fast-moving cold front will scoot by to the north of
our region Sunday night and Monday morning. This passing front
could produce a brief rain shower or two or sprinkles in western
and central Maryland and across the northern Alleghenies. For
much of the rest of the area, it will be dry and remain
seasonable during this timeframe and the remainder of Monday.
Highs Monday will likely be in the lower to middle 60s.

A second area of high pressure will build into the region Tuesday.
Dry conditions are expected again for most places. High and low
temperatures will be seasonable with highs in the lower to
middle 60s and lows in the lower 40s.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
VFR conditions are expected to continue through tonight with high
pressure nearby. A low pressure system will approach on
Thursday. Have favored slower introduction of sub-VFR clouds
shown in probabilistic and high resolution data (think LAMP is
way too fast) given incipient very dry airmass in place. IFR
ceilings may move into CHO during the afternoon, but will likely
wait until evening across the metro hubs. Meanwhile, rain will
arrive around midday in CHO and mid to late afternoon elsewhere
(with possible sprinkles sooner)...potentially becoming moderate
at times Thursday evening. IFR conditions will last into Friday
morning as rain gradually ends. Winds will remain light out of
the east and southeast with gusts less than 15 kts.

Cloud cover should diminish slowly Friday with a return to VFR
by afternoon. Abundant sunshine is likely Saturday. VFR
conditions are in the forecast for the weekend, accompanied by
persistent north/northwesterly winds. North/northwest winds
gusting up to 25 kt are possible Saturday afternoon, diminishing
Sunday.

&&

.MARINE...
E/SE gusts around 15 kts or less are expected through tonight
as high pressure passes to the north. Sub-SCA level winds
continue into Thursday morning with light to moderate rain
traversing the waters during the afternoon and evening as
another front sweeps through the region. Winds will switch to
the southeast with gusts increasing to near 20 kts for much of
the area by late Thursday afternoon.

Northwesterly breezes should be fairly persistent on Friday into
Saturday. Small Craft Advisories will likely be needed at times
during this period. Some wind gusts could be near gale force over
the southern waters Friday night into Saturday morning. Weakening
gradients should allow for north northwest winds to fall below Small
Craft Advisory levels by Sunday.

&&

.FIRE WEATHER...
Widespread wetting rains reach the area Thursday into Thursday
night. This should decrease the fire weather threat through
Friday. Rainfall amounts of a quarter to a half an inch are
expected areawide.

&&

.TIDES/COASTAL FLOODING...
Water level anomalies are increasing quickly due to onshore flow and
an approaching full moon. Minor flooding appears likely for
several locations Thursday and Friday as a low pressure system
tracks nearby. Annapolis may come close to moderate flood. Water
levels will drop Friday night as the low departs.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 4 PM Thursday to midnight EST
     Thursday night for ANZ531-538>540.
     Small Craft Advisory from 4 PM Thursday to 7 PM EST Friday for
     ANZ532>534-537-541>543.

&&

$$

SYNOPSIS...DHOF/EST
NEAR TERM...ADS/DHOF/EST
SHORT TERM...DHOF/EST
LONG TERM...KLW
AVIATION...ADS/KLW/DHOF/EST
MARINE...ADS/KLW/DHOF/EST
FIRE WEATHER...EST
TIDES/COASTAL FLOODING...ADS