Herndon, Virginia Weather Forecast Discussion

933
FXUS61 KLWX 290749
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
349 AM EDT Mon Sep 29 2025
.SYNOPSIS...
High pressure builds south from eastern Canada through much of the
week. A strong cold front will track across the area Tuesday
night bringing cooler and drier weather for the middle and
latter part of this week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Southerly upper level flow ahead of an upper level trough to our
southwest will transport high level clouds into area today into
Tue morning. Expect a high level overcast today that will become
denser/thicker through time. Moisture being drawn northward
ahead of Imelda will begin to interact with an upper level
trough to our west to bring light rain tonight, possibly
reaching as far north as Route 7 in northern VA. However, only
areas down by Charlottesville and Nelson County seem like a lock
to get some rain. Rainfall amounts of a quarter up to half inch
are possible from Charlottesville south, while areas to the
north may only see a trace up to a tenth of an inch.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Moisture from Imelda will start pulling away from the area
Tuesday morning with rain completely out by Tue afternoon,
although high level clouds will be slower to depart the area. A
sharp cold front will cross the area Tue night bringing a
noticeable cooling trend for the middle portion of the week.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Model spread is fairly low through the long term period as strong
Canadian high pressure builds along the east coast. A large upper
level ridge keeps the jet stream well to the north and the weather
dry. Temperatures will be below normal Thursday and Friday. The
ridging shifts slightly eastward over the weekend, allowing
southerly flow to bring a warming trend.
&&
.AVIATION /07Z MONDAY THROUGH FRIDAY/...
Thickening high level clouds through tonight with light rain or
sprinkles possible late tonight into Tue morning, but no flight
restrictions expected. A strong cold front will cross the area
Tue night bringing a notable increase in northerly winds.
No significant weather is expected Thursday and Friday as strong
high pressure builds overhead. However, some northeasterly wind
gusts of 15 to 20 kt remain possible Thursday.
&&
.MARINE...
Winds should strengthen Tue into early Wed as pressure gradient
tightens between Imelda and high pressure to the north. SCA
conditions are anticipated Tuesday through Tue night.
A tight pressure gradient between high pressure to the north and
Imelda well off the coast will likely cause Small Craft Advisory
conditions to continue into Thursday with northeasterly winds.
Lighter winds are expected Friday as the high moves overhead.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...ADS
AVIATION...ADS/LFR
MARINE...ADS/LFR

NWS LWX Office Area Forecast Discussion