Flash Flood Warning 101, NWS Baltimore/Washington

924 
WGUS71 KLWX 160152
FFSLWX

Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
952 PM EDT Tue Jul 15 2025

VAC177-160202-
/O.CAN.KLWX.FF.W.0101.000000T0000Z-250716T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Spotsylvania VA-
952 PM EDT Tue Jul 15 2025

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTH CENTRAL SPOTSYLVANIA 
COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

A Flood Watch remains in effect until 1200 AM EDT for portions of 
central, northwest, and western Virginia.

&&

LAT...LON 3813 7777 3813 7776 3806 7766 3804 7765
      3801 7767 3801 7771 3802 7772 3802 7773
      3803 7773 3803 7775 3804 7775 3805 7775
      3805 7777 3806 7778 3808 7779 3808 7781
      3813 7778

$$

CJL

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
332 PM EDT Tue Jul 15 2025

.SYNOPSIS...
A frontal boundary will remain nearly stationary over the region
today before dissipating by Wednesday morning. Another cold
front moves through the region late Friday before stalling
nearby through the weekend, possibly into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Relative to yesterday, the local radar mosaic shows a much less
active setup across the region. This is in response to a
building mid/upper ridge which is settling over the central
Appalachians into the Mid-Atlantic states. A rather subdued
looking cumulus field is evident on the GOES-19 visible
satellite channel. There are some localized enhancements across
the Blue Ridge Mountains as well as along a west-east boundary
stretching from St. Mary's County into central Virginia. Both of
these areas have a modest signal for enhanced rainfall amounts.

Flood Watches remain in effect across Augusta, Nelson,
Albemarle, and St. Mary's counties until midnight. This also
includes the central Virginia Blue Ridge. This particular zone
is where convection is generally ongoing, but is rather
disorganized and more transient in nature. The limited upward
growth is evidenced in the dearth of lightning activity.
However, flash flooding remains possible in these areas through
the afternoon and evening hours, particularly as storms
intensify. As noted by the precipitable water values averaging
just above 2 inches, a tropical air mass remains in place across
areas south of I-66. Given such an air mass, rainfall rates
inside the watch area could approach 1.50 to 2.50 inches per
hour.

For locations north of I-66, expect a mainly dry forecast
through the remainder of the day. High temperatures across the
region should top out in the mid/upper 80s to near 90 degrees.
With dew points ranging from the upper 60s to mid 70s, heat
indices will largely be in the mid/upper 90s. Heading into the
tonight, any convective chances to the south wane by after
midnight. A mild and humid air mass persists with forecast lows
in the upper 60s to mid 70s (60s for the mountains). Light winds
combined with saturation of the low levels will support patchy
fog, some locally dense. Areas that see heavy rainfall today and
the more vulnerable low-lying river valleys have the best shot
at dense fog.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As the upper ridge departs to the east, heights again lower on
Wednesday in response to a combination of shortwaves and
convective-induced perturbations. The energetics aloft will
again move into the very moist and unstable environment across
the Mid-Atlantic states. A preponderance of 12Z high-resolution
models favor semi-robust convection across the region on
Wednesday afternoon and evening. Not surprisingly, the placement
of convective maxima vary from model to model, but the signal is
certainly present. Area-wide precipitable water values return to
the 2 to 2.25 inch range which is up around the 95th percentile
and above for mid-July. This combination of identifiable forcing
mechanisms with anomalous tropical moisture will enhance the
risk of flash flooding on Wednesday. The Weather Prediction
Center has upgraded much of the area into a Slight Risk for
excessive rainfall. Flood Watches will likely be needed at some
point given Wednesday's setup.

Severe weather is not completely out of the question either as
the Storm Prediction Center has raised the risk area to a
Marginal across much of the region. Taller thunderstorms will
be capable of carrying water-loaded downdrafts to the surface
which would bring a threat of damaging wind gusts. Any
convective threats should wane after dark given the loss of
diabatic heating.

On the temperature side, expect another typical summertime day
with highs rising into the upper 80s to low 90s. Adding the
persistent humidity in the air will carry heat indices to around
97 to 102 degrees. The only relief would come in the scattered
to numerous thunderstorms across the region. Warm and humid
conditions again persist into the night with low temperatures in
the low/mid 70s. Like previous nights, patchy fog may develop
across the region.

Moving into Thursday, the local area appears to be in between
systems which should yield a reduced threat of convection.
However, temperatures do spike further with high temperatures
pushing into the 90 to 95 degree range. Adding the persistent
high dew points carries heat indices to around 100 to 105
degrees. This would near Heat Advisory thresholds so this bears
some watching. Little to no relief is expected into the night
with Thursday night's low temperatures well into the 70s (mid
60s to low 70s for mountain locales).

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The longwave pattern across the CONUS should remain fairly
consistent through the long term period, with zonal flow across the
northern tier of states and subtropical ridging in place over the
south. Multiple disturbances will pass to our north within zonal
flow during the long term period. This will keep conditions active,
with daily chances for showers and thunderstorms across the
area. Temperatures will remain near average, with highs in the upper
80s to around 90, and lows in the upper 60s and lower 70s.

While an instance or two of damaging winds or flash flooding can't
be ruled out any day, Friday appears to be the day with the greatest
chance for damaging winds or flash flooding. A cold front will
approach from the north and west that day as deep moisture pools
ahead of the front and mid-level flow increases to around 25-30
knots.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
With the focus for convection shifting to the south, only KCHO
has convective groups in the TAF for today. At this point, any
activity has been lacking so will monitor trends during the next
shift. Otherwise, winds remain on the lighter side with some
restrictions possible heading into the overnight hours. Patchy
fog could yield some MVFR conditions, particularly across the
more western terminals.

Wednesday is looking fairly active across the area with the
potential for sub-VFR conditions at all TAF sites. There was
enough of a signal to go with a prevailing -TSRA group at KDCA,
KIAD, and KBWI between 20-00Z. A PROB30 group remains for the
few hours before given the potential for earlier convective
development. Otherwise, southerly winds increase through the day
with possible gusts up to 15 knots. Like previous nights, patchy
fog may develop. Convective chances decrease on Thursday, but
cannot rule out brief restrictions as air mass thunderstorms pop
up.

Prevailing VFR conditions are expected on both Friday and Saturday.
A thunderstorm could lead to brief restrictions either afternoon or
evening. Winds will generally be out of the northwest on Friday, and
out of the south on Saturday.

&&

.MARINE...
Sub-advisory caliber winds remain for the next 24 hours given
weak gradients. However, a ramp up is eventually expected during
the second half of Wednesday into Thursday. The uptick in
southerly winds may lead to some localized channeling effects,
particularly across the southern-most waters. Small Craft
Advisories may be needed from Wednesday evening into portions of
Thursday as gusts rise to 20 to perhaps 25 knots.

A threat for convection on Wednesday will lead to some hazardous
marine conditions, particularly during the afternoon/evening
hours. Special Marine Warnings may be needed for any of the
stronger storms. Convective chances decrease into Thursday, but
some isolated to scattered storms may fire up during peak
heating.

Sub-SCA level winds are expected on both Friday and Saturday. Winds
will generally be out of the northwest on Friday, and out of the
south on Saturday.

&&

.TIDES/COASTAL FLOODING...
After a brief lull in the warm advection flow regime, expect a
return to the prolonged period of southeasterly winds. This will
lead to elevated tidal anomalies through midweek, particularly
across Annapolis. This location will see Action stage at
times, particularly during the higher of the two astronomical
high tide cycles. However, outside of freshwater influences from
heavy rainfall, the threat for tidal flooding appears low.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Flood Watch until midnight EDT tonight for MDZ017.
VA...Flood Watch until midnight EDT tonight for VAZ025-036-037-508.
WV...None.
MARINE...None.

&&

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

Hazardous Weather Outlook
National Weather Service Baltimore MD/Washington DC
105 PM EDT Tue Jul 15 2025

ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508-
VAZ053>057-527-161715-
Chesapeake Bay north of Pooles Island MD-
Chesapeake Bay from Pooles Island to Sandy Point MD-
Chesapeake Bay from Sandy Point to North Beach MD-
Chesapeake Bay from North Beach to Drum Point MD-
Chesapeake Bay from Drum Point MD to Smith Point VA-
Tidal Potomac from Key Bridge to Indian Head MD-
Tidal Potomac from Indian Head to Cobb Island MD-
Tidal Potomac from Cobb Island MD to Smith Point VA-
Patapsco River including Baltimore Harbor-
Chester River to Queenstown MD-Eastern Bay-
Choptank River to Cambridge MD and the Little Choptank River-
Patuxent River to Broomes Island MD-
Tangier Sound and the inland waters surrounding Bloodsworth
Island-District of Columbia-Cecil-Southern Baltimore-
Prince Georges-Anne Arundel-Charles-St. Marys-Calvert-
Central and Southeast Montgomery-Central and Southeast Howard-
Southeast Harford-Fairfax-Arlington/Falls Church/Alexandria-
Stafford-Spotsylvania-King George-
Central and Southeast Prince William/Manassas/Manassas Park-
105 PM EDT Tue Jul 15 2025

This Hazardous Weather Outlook is for the Maryland portion of the
Chesapeake Bay, Tidal Potomac River, and I-95 corridor through
central Maryland, northern Virginia, and District of Columbia.

.DAY ONE...This Afternoon and Tonight

A Flood Watch has been issued for the threat of flash flooding
across St. Mary's County. This is in effect until midnight.

Elsewhere, isolated instances of flash flooding are possible this
afternoon.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508-
526-WVZ050>053-055-161715-
Washington-Frederick MD-Carroll-Northern Baltimore-
Northwest Montgomery-Northwest Howard-Northwest Harford-Augusta-
Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke-Nelson-
Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper-
Northern Fauquier-Southern Fauquier-Western Loudoun-
Eastern Loudoun-Northern Virginia Blue Ridge-
Central Virginia Blue Ridge-Northwest Prince William-Hampshire-
Morgan-Berkeley-Jefferson-Hardy-
105 PM EDT Tue Jul 15 2025

This Hazardous Weather Outlook is for portions of eastern West
Virginia, northern and central Virginia, and central and western
Maryland.

.DAY ONE...This Afternoon and Tonight

A Flood Watch has been issued for the threat of flash flooding
across Nelson, Albemarle, and Augusta counties, as well as the
Central Virginia Blue Ridge. This is in effect from 2 PM until
midnight.

Elsewhere, scattered instances of flash flooding are possible
this afternoon.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

MDZ501-502-509-510-VAZ503-504-WVZ501>506-161715-
Extreme Western Allegany-Central and Eastern Allegany-
Western Garrett-Eastern Garrett-Western Highland-Eastern Highland-
Western Grant-Eastern Grant-Western Mineral-Eastern Mineral-
Western Pendleton-Eastern Pendleton-
105 PM EDT Tue Jul 15 2025

This Hazardous Weather Outlook is for the Allegheny Front
counties in western Maryland, eastern West Virginia, and Highland
County Virginia.

.DAY ONE...This Afternoon and Tonight

Scattered instances of flash flooding are possible this
afternoon.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Preliminary Local Storm Report
National Weather Service Baltimore MD/Washington DC
747 PM EDT Tue Jul 15 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0730 PM     Flash Flood      2 SSW Arrington         37.65N  78.92W
07/15/2025                   Nelson             VA   911 Call Center

            Road washed out in the 2000 block of South Powells
            Island Rd.

&&

Event Number LWX2506193

CJL