Gaithersburg, Maryland 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

956
FXUS61 KLWX 141440
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1040 AM EDT Mon Jul 14 2025

.SYNOPSIS...
A cold front approaches from the northwest today before stalling and
dissipating overhead through midweek. Another cold front approaches
and moves through the region at the end of the week and into the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
*10:30 AM UPDATE*
The forecast largely remains on track although a westward expansion
of the Flood Watch was made to cover Hardy, Hampshire, Mineral,
and Allegany counties. There remains a strong enough signal in
the high-resolution guidance for these counties to be included.
Otherwise, a stratus deck east of the Blue Ridge has slowly
begun to erode, particularly along/east of I-95. GOES-19 visible
satellite imagery shows cloud streets orienting with the low-
level flow. While most of these have not begun to convect,
scattered shower activity continues to percolate over portions
of the Chesapeake Bay. Off to locations west of the Blue Ridge,
skies are more cloud free with some cumulus already bubbling up
over the higher terrain of western Rockingham and eastern Hardy
counties. Given the upstream forcing and further heating of the
surface, expect additional vertical development over the next
couple of hours.

As sampled by the 12Z IAD sounding, a tropical air mass remains
in place with a precipitable water value of 2.14 inches. This
runs fairly close to the running daily maxima for mid-July. The
profile is nearly saturated through the column with a low-level
RH of 89% and mid-level RH of 83%. As such, be the look out for
very heavy rainfall with some pockets of 2 to 3 inches per hour
being possible. Storm total amounts up to 3 to 6 inches are
possible where convection is slower moving and where repeat
convection takes place.

*PREVIOUS DISCUSSION*
Thunderstorm chances increase today as a cold front approaches from
the northwest, creating synoptic level forcing. A warm and humid
airmass yields plenty of instability with 2000-3000 J/kg of SBCAPE.
Storms will be more progressive in nature compared to previous days
and will be slightly more organized with around 15-20 knots of
shear. Primary hazards expected with convection today will be
damaging winds gusts with saturated model soundings indicating
a threat for wet downbursts.

In addition to the severe weather threat, a saturated airmass
indicated by model guidance showing PWATS exceeding 2" will lead to
a risk of Flash Flooding across much of the area. A Flood Watch
has been issued for counties along and east of the I-81
corridor. Within convection, heavy rainfall is expected with
precipitation totals of 1-3" possible. Locally higher amounts
are possible within strong storms. Rainfall rates up to 2" per
hour are possible which may lead to scattered instances of
flash flooding.

High temperatures will be in the 80s for most with isolated areas
reaching the low 90s. Warm dew point temperatures will lead to heat
indices rising into the upper 90s for the area. Overnight low
temperatures will be in the 60s to 70s.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A frontal boundary stalled over the region will continue daily
shower and thunderstorm chances Tuesday and Wednesday. A lack of
forcing will limit thunderstorm coverage each day with precipitation
chances highest in the southern portions of the forecast area on
Tuesday. On Wednesday, shower and thunderstorm chances are greatest
in the afternoon during peak daytime heating. Coverage will be more
widespread on Wednesday as the stalled front lifts northward.

High temperatures will be in the 80s for most Tuesday and Wednesday.
Highest ridgetops will stay in the 70s while isolated locations
in the valleys and southern portions of the forecast area reach
the 90s. Overnight low temperatures will be in the 60s for most
west of the Blue Ridge and in the low 70s along and east of the
Blue Ridge.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
While we can`t guarantee a dry day or period of time in the extended
forecast, there does appear to be a lull in the shower and
thunderstorm activity across the eastern two-thirds of the region on
Thursday. Most shower and thunderstorm activity should occur in the
western third Thursday afternoon and evening due to a trough of low
pressure nearby. Some of this activity could spread farther east
Thursday evening, but confidence is low. High temperatures should be
in the lower to middle 90s.

By Friday, the possibility of lull in convection could go away as a
cool front pushes southeast across the region Friday midday through
Friday evening. The front could spawn shower and thunderstorm
activity across all parts of the region. High temperatures again
should reach the lower 90s.

A couple of showers and a thunderstorm could linger or pop up on
Saturday with the heating of the day, but a weak area of high
pressure could win out and push into the region from the northwest.
This high would bring a break in convection once again with a drying
northwest to north wind. Humidity may not drop too far but there may
be just enough dry air moving in the lower levels to restrict
convection much of the day Saturday. High temperatures should reach
the middle to upper 80s.

Dry conditions could linger through the day Sunday with high
pressure still holding on. A slight upslope component to the wind in
the mountains in the west could spawn a few showers. Overall,
conditions should still be tranquil in most areas. Highs in the
middle to upper 80s again.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Showers and thunderstorms will likely impact the terminals today as
a cold front approaches from the west. Within showers and
thunderstorms, gusty winds, frequent lightning, and flight
restrictions are expected. Winds remain out of the
south/southeast today, blowing 5 to 10 knots in the afternoon
and becoming light and variable overnight.

A cold front stalls nearby Tuesday and Wednesday with showers and
thunderstorms possible each day. Flight restrictions are
expected during showers and thunderstorms. Winds remain out of
the south/southeast each day, becoming light and variable each
night.

Most of any shower and thunderstorm activity may be held to MRB and
CHO on Thursday. VFR conditions for the terminals, despite a brief
MVFR development with convection. Winds southwest 5 to 10 knots. VFR
conditions should start the day Friday, but MVFR to IFR conditions
may develop Friday midday through Friday evening at any of the
terminals. Once convection clears, VFR conditions should redevelop.
Winds southwest to west 5 to 10 knots.

&&

.MARINE...
Light winds are expected over the waters through Tuesday. Winds
remain below SCA criteria each day, blowing 5 to 10 knots Monday and
Tuesday afternoon. Daily shower and thunderstorm activity may lead
to SMWs being needed. Winds increase to near SCA criteria Wednesday
evening due to southerly channeling. A Small Craft Advisory may be
needed.

The only marine hazards that could occur Thursday through Friday
night would be Special Marine Warnings for thunderstorms that could
develop and move out over the Potomac River and Chesapeake Bay
waters Friday midday through Friday evening. Winds generally
southwest to west 10 knots with exception to higher gusts in
thunderstorms.

&&

.HYDROLOGY...
A Flood Watch for the threat of flash flooding is in effect from
2 PM until midnight across all locations east of the Allegheny
Front. A tropical air mass remains in place across the area.
With precipitable water values into the 2 to 2.25 inch range,
this easily rises into the 95th percentile for mid-July. Very
high rainfall rates are possible, generally up to 2 to 3 inches
per hour within some of the more potent and slow moving cores.
Areas hit more recently by flooding rains will certainly be more
vulnerable to additional heavy thunderstorms today. While most
will not see this, storm totals approaching 4 to 6 inches are
not out of the question in areas of training/slow moving
convection.

&&

.TIDES/COASTAL FLOODING...
A prolonged period of southeasterly winds will lead to elevated
tidal anomalies through midweek. This carries most of the tidal
locations into Action stage, particularly during the higher of
the two astronomical high tide cycles. Sensitive locations, such
as Annapolis, are forecast to stay just below Minor stage
during the high tide cycles this morning.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Flood Watch from 2 PM EDT this afternoon through this evening
     for DCZ001.
MD...Flood Watch from 2 PM EDT this afternoon through this evening
     for MDZ003>006-008-011-013-014-016>018-501>508.
VA...Flood Watch from 2 PM EDT this afternoon through this evening
     for VAZ025>031-036>040-050-051-053>057-501-502-505>508-
     526-527.
WV...Flood Watch from 2 PM EDT this afternoon through this evening
     for WVZ050>053-055-503-504.
MARINE...Flood Watch from 2 PM EDT this afternoon through this evening
     for ANZ530.

&&

$$

SYNOPSIS...AVS
NEAR TERM...AVS/BRO
SHORT TERM...AVS
LONG TERM...KLW
AVIATION...AVS/KLW
MARINE...AVS/KLW
HYDROLOGY...BRO
TIDES/COASTAL FLOODING...LWX