Gaithersburg, Maryland 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

101
FXUS61 KLWX 060745
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
345 AM EDT Sun Oct 6 2024

.SYNOPSIS...
High pressure to the north will slide offshore early today as a
strong cold front approaches from the Ohio River Valley. This
front will bring renewed chances for showers and thunderstorms
this evening into early Monday morning. Canadian high pressure
builds in behind the front with below normal temperatures
expected for much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Patches of fog have developed early this morning, primarily
along the valleys west of the Blue Ridge, and some low clouds
have hovered around CHO. Fog and low clouds will continue to
develop until sunrise, but are not expected to be as widespread
as yesterday morning with drier air in place. What does develop
should quickly burn off.

Mostly sunny skies and southerly flow will be in place until
this evening, allowing high temperatures to reach into the mid-
upper 70s for much of the area. A cold front approaches from
the west this evening. CAMs have remained in good agreement on
timing of showers and thunderstorms associated with the front,
generally arriving at the Allegheny Front late this evening
(between 10PM- midnight). The Storm Prediction Center does have
a Marginal Risk (level 1 of 5) of severe thunderstorms for
western MD and the eastern WV panhandle, and general thunder to
the Blue Ridge. The more favorable environment is expected to be
to our northwest over eastern Ohio/western PA, where SPC has a
Slight Risk (2 of 5).

As the SW-NE oriented line of showers and thunderstorms crosses
the mountains, convection is expected to fall apart given the
less favorable environment and the loss of daytime heating. CAMs
do vary somewhat on how far east storms make it before
diminishing, but most likely any stronger storms would be
restricted to the Alleghenies and the immediate east, though a
few making it as far as the Blue Ridge can`t be ruled out. The
primary threat of any stronger storms would be damaging winds
and hail. As the cold front advances east and storms fizzle out,
some isolated showers and thunderstorms are possible from the
Blue Ridge to the I-95 corridor, expected between midnight-2AM.

Winds turn NW behind the front, dropping low temperatures into
the 40s and low 50s in the mountains. East of the Blue Ridge
lows in the upper 50s to low 60s are expected.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The beginning of the work week kicks off a pattern of quieter
weather for the area. The cold front and associated precip will
swiftly exit early Monday morning and high pressure builds in
behind it with mostly sunny skies. With building high pressure,
the tight pressure gradient will result in breezy conditions,
northwest winds gusting 20-25 mph. As cooler air advects in,
high temperatures are only expected to reach the upper 60s to
mid 70s, and 50s in the mountains.

Tuesday will be similar, temperatures dropping a few more
degrees and winds diminishing slightly as the colder air mass
settles in. Highs in the upper 60s and low 70s will be near to
slightly below normal.

Low temperatures both nights drop into the 40s for most of the
area. Frost is possible in the mountains as temps drop into the
mid-upper 30s.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
High pressure will gradually build in from the Great Lakes Wednesday
into Thursday as a deep upper trough initially located over the
Northeast/Quebec progresses eastward toward the Canadian Maritimes.
Northwesterly winds are expected during that time ahead of the
approaching high, which will maintain a cool and dry airmass over
the region. Mostly sunny skies are expected both days, along with
high temperatures in the 60s. The high will build overhead Thursday
night, setting the stage for ideal radiational cooling conditions.
Low temperatures will be in the 30s and lower 40s for most, and
frost/freeze headlines may potentially be needed for portions of the
area.

Flow aloft will turn more zonal in nature, and the surface high will
move to our south late in the week into next weekend. This will
cause winds to turn southwesterly, which will advect a warmer
airmass into the region. In the absence of any notable upper air
features, sunny skies and dry conditions are forecast, along with a
gradual warming trend in temperatures. Highs on Friday are expected
to be near 70, with mid 70s on Saturday. Overnight lows will
generally be in the 40s Friday night, with upper 40s and lower 50s
Saturday night.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
Patches of fog and low clouds have developed early this morning
near and west of the Blue Ridge. MVFR vsbys are possible just
before sunrise for MRB and CHO, but conditions should quickly
improve to VFR after sunrise. Mostly sunny skies and south winds
5-10kt are expected during the day.

This evening, a cold front approaches from the NW, and
associated showers and thunderstorms are expected to diminish
east of the mountains. As such, the greatest chances of
precipitation with this frontal passage are west of MRB, but
isolated to scattered showers (and maybe thunderstorms) are
possible for MRB (10PM- midnight) and BWI/MTN (midnight-4AM).
Sub-VFR conditions are possible but confidence wasn`t high
enough to include in TAF explicitly. As the front exits early
Monday morning, any reductions should improve quickly.

High pressure builds in Monday into Tuesday, with mostly sunny
skies and NW winds gusting 15-20 kts. VFR conditions and
northwesterly winds are expected on both Wednesday and
Thursday.

&&

.MARINE...
A cold front crosses the waters tonight into Monday. Winds
strengthen out of the south before the frontal passage tonight,
and Small Craft Advisories are in effect for the Chesapeake Bay
and the lower tidal Potomac from 8PM tonight through 6AM Monday
morning.

Behind the front, gusty NW flow could necessitate further SCAs.
Winds likely diminish by Tuesday. Northwesterly winds are expected
over the waters on both Wednesday and Thursday, with gusts to
around 15 kt possible at times.

&&

.TIDES/COASTAL FLOODING...
Southerly flow today should allow tidal anomalies to increase once
again. No flooding is anticipated during the day today, but
Annapolis and DC SW Waterfront may come close to flooding tonight.
Winds will turn northwesterly behind a cold front later tonight into
early Monday morning. A prolonged period of offshore flow is
expected thereafter, which should lead to lower tidal anomalies and
a reduced threat for coastal flooding.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 8 PM this evening to 6 AM EDT Monday
     for ANZ530>534-537-539>541-543.

&&

$$

SYNOPSIS...BRO/EST
NEAR TERM...CAS
SHORT TERM...CAS
LONG TERM...KJP
AVIATION...KJP/CAS
MARINE...KJP/CAS
TIDES/COASTAL FLOODING...KJP