River Flood Watch 28, NWS Baltimore/Washington

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
343 PM EDT Wed Sep 1 2021

.SYNOPSIS...
The remnants of Ida will interact with a mid-latitude trough as it
tracks across our area today. Ida will depart off to the north and
east tomorrow, allowing high pressure to build in at the surface
for Friday into the first half of the weekend.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
An active day continues as the remnants of Ida progress across
the area. Numerous storms are ongoing across the area, some of
which have a history of producing tornadoes. The main initial
band of storms is situated along the bay northward to
Baltimore/Harford Counties at the moment, and will continue to
progress off toward the north and east. A tornado threat
persists in association with these storms, and the threat for
organized straight line winds is increasing as well as this
convective band continues to grow upscale. This band of storms
should clear the forecast area by around 5 or 6 PM. Additional
showers and thunderstorms are developing behind this initial
band. Model soundings indicate that hodographs will become less
favorable for tornadoes with this activity, but some threat for
severe thunderstorms can't be ruled out. Flash flooding is
ongoing across northern portions of the forecast area (see
hydrology section for more details). Showers and storms will
clear the area from west to east during the evening to early
overnight hours.

Gusty north to northwesterly winds will filter into the area
behind the precipitation this evening. As a result, a Wind
Advisory has been issued this evening for portions of northern
MD and the Central VA Blue Ridge. Wind gusts will likely
approach 50 mph for a few hours this evening in the advisory
area. Elsewhere, gusts of 30-40 mph appear likely for a short
time. Widespread wind gusts of 20-30 mph are expected to
continue through the night.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
The remnants of Ida will track off toward the north and east
tomorrow. The pressure gradient between the remnants of Ida and
an area of high pressure over the Great Lakes will maintain
gusty north to northwesterly winds over the area, with gusts of
20-30 mph common. Skies will be mostly sunny, and temperatures
will be much cooler, with high temperatures in the mid-upper
70s. Humidity levels will also be much lower, with dewpoints in
the 50s. Friday will feature much of the same as high pressure
continues to build in from the Great Lakes. Skies will stay
mostly sunny, but winds will slacken a bit. High temperatures
will once again be in the mid-upper 70s and dewpoints will hold
in the 50s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A region of Canadian high pressure will still be overhead Saturday
keeping highs in the upper 70s to near 80 for most. A cold front
will move towards the region on Sunday from the Great Lakes/Ohio
Valley. This will bring the risk for showers. Given the limited
instability, the thunderstorm potential remains low. Once the front
passes, a drier and cooler air mass will work in for the first half
of next week. Highs will generally be in the upper 70s to low 80s,
with 60s in the mountains. Lows early next week could dip into the
40s across the colder valleys of the Allegheny Front.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
Showers and thunderstorms will continue to impact the terminals
over the next few hours, leading to temporary restrictions. The
precipitation will move out of the area this evening. Gusty
north to northwesterly winds will move in behind the system this
evening, with gusts of 30-35 knots possible for a few hours.
VFR conditions are expected tomorrow with north to northwesterly
winds gusting to around 20 knots. VFR conditions and lighter
winds are expected on Friday.

VFR conditions are expected Saturday and Sunday with the flow
becoming southeast ahead of the cold front.

&&

.MARINE...
Numerous showers and thunderstorms will traverse the waters this
afternoon and evening. These storms will be capable of producing
high winds and waterspouts. In addition, a Gale Warning remains
in effect through tonight. Winds are currently southerly, but
will turn north to northwesterly this evening and increase. SCA
appear likely through tomorrow. Thereafter, sub-SCA conditions
are expected.

Winds will remain below SCA criteria for the weekend.

&&

.HYDROLOGY...
The remnants of Ida will interact with a stalled frontal
boundary over our region today. This will result in periods of
very heavy rainfall, particularly near the MD/PA border and into
eastern WV. Rainfall amounts have trended downward a little,
but significant rainfall is still possible. Multiple rounds of
heavy rain would result in scattered to numerous instances of
flooding/flash flooding, some considerable. Additionally, in the
days following, expect river flooding to become an issue. Many
locations are forecast to enter minor or moderate flood stage,
and river flood watches have been issued accordingly for
locations that are expected to reach flood stage in the next 48
hours. We will receive the latest forecast guidance from the
MARFC this afternoon and will update river watches and
potentially warnings as needed.

&&

.TIDES/COASTAL FLOODING...
Remnants of Ida appear to be moving faster. This may ultimately
limit the time of higher anomalies in the northern part of the bay
as winds quickly become northerly this evening. However, at least a
few instances of minor tidal flooding will remain possible across
the area this evening. Have maintained a Coastal Flood Watch
for Annapolis since guidance continues to indicate it will be
close. DC/Georgetown may need watches as well depending on the
latest forecasts of freshwater coming down the Potomac.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Flash Flood Watch through Thursday morning for DCZ001.
MD...Flash Flood Watch until 2 AM EDT Thursday for MDZ001-003-501-
     502.
     Flash Flood Watch through Thursday morning for MDZ004>006-008-
     011-013-014-016>018-503>508.
     Coastal Flood Watch from 10 PM EDT this evening through
     Thursday morning for MDZ014.
     Coastal Flood Advisory until 5 PM EDT this afternoon for
     MDZ014.
VA...Flash Flood Watch until 2 AM EDT Thursday for VAZ025>031-503-
     504.
     Flash Flood Watch through Thursday morning for VAZ036>040-
     050>057-501-502-505>508.
WV...Flash Flood Watch until 2 AM EDT Thursday for WVZ050>053-055-
     501>506.
MARINE...Flash Flood Watch through Thursday morning for ANZ535.
     Gale Warning until 6 AM EDT Thursday for ANZ530>543.

&&

SYNOPSIS...KJP
NEAR TERM...KJP
SHORT TERM...KJP
LONG TERM...CPB
AVIATION...KJP/CPB
MARINE...KJP/CPB
HYDROLOGY...LWX
TIDES/COASTAL FLOODING...LWX

Hazardous Weather Outlook
National Weather Service Baltimore MD/Washington DC
343 PM EDT Wed Sep 1 2021

ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508-
VAZ052>057-021945-
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-Prince William/Manassas/Manassas Park-Fairfax-
Arlington/Falls Church/Alexandria-Stafford-Spotsylvania-
King George-
343 PM EDT Wed Sep 1 2021

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 Tornado Watch is in effect through 7 PM this evening. Tornadoes
will be possible.

A Flash Flood Watch is in effect through tonight. Heavy tropical
rainfall could result in flash flooding. Flooding on mainstem
rivers may then persist through the end of the week.

A Coastal Flood Watch for potential moderate tidal flooding is in
effect for Anne Arundel County from Wednesday evening through
Thursday morning.

A River Flood Watch is in effect for the Potomac River from the
District and upstream for Friday.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

A Gale Warning is in effect for portions of the waters through
midday Thursday.

.SPOTTER INFORMATION STATEMENT...

Spotters are activated.

MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508-
WVZ050>053-055-021945-
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-Hampshire-Morgan-Berkeley-Jefferson-
Hardy-
343 PM EDT Wed Sep 1 2021

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 Tornado Watch is in effect through 7 PM this evening east of the
Blue Ridge, except from Madison County Virginia and south to
Nelson County. Tornadoes will be possible.

A Flash Flood Watch continues for the entire outlook area through
tonight. Heavy tropical rainfall could result in flash flooding.

A River Flood Watch is in effect for several river basins in
parts of western and northern Maryland and the eastern panhandle
of West Virginia starting Thursday morning.

A Wind Advisory is in effect for portions of northern Maryland,
eastern West Virginia and the northern Blue Ridge in Virginia for
this evening into the overnight.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters are activated.

MDZ001-501-502-VAZ503-504-WVZ501>506-021945-
Garrett-Extreme Western Allegany-Central and Eastern Allegany-
Western Highland-Eastern Highland-Western Grant-Eastern Grant-
Western Mineral-Eastern Mineral-Western Pendleton-
Eastern Pendleton-
343 PM EDT Wed Sep 1 2021

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

A Flash Flood Watch continues through tonight. Heavy tropical
rainfall could result in flash flooding.

A River Flood Watch is in effect for a few river basins in parts
of western Maryland and eastern West Virginia starting Thursday
morning.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters are activated.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
249 PM EDT WED SEP 01 2021

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

0216 PM     TORNADO          ANNAPOLIS               38.97N  76.50W
09/01/2021                   ANNE ARUNDEL       MD   EMERGENCY MNGR

            COUNTY EMERGENCY MANAGEMENT REPORTS TREES AND WIRES
            DOWN, AND DAMAGE TO BUILDINGS THROUGHOUT THE RIVA,
            WOODLAND BEACH, AND ANNAPOLIS AREA.

&&

EVENT NUMBER LWX2105795

CPB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
308 PM EDT WED SEP 01 2021

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

0259 PM     FLASH FLOOD      3 NNW UTICA             39.56N  77.41W
09/01/2021                   FREDERICK          MD   911 CALL CENTER

            WATER RESCUE NEAR INTERSECTION OF HESSONG BRIDGE ROAD
            NEAR AND BLACKS MILL ROAD.

&&

EVENT NUMBER LWX2105796

CPB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
310 PM EDT WED SEP 01 2021

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

0310 PM     FLOOD            THURMONT                39.62N  77.41W
09/01/2021                   FREDERICK          MD   911 CALL CENTER

            AT LEAST 20 ROADS CLOSED IN THE NORTHERN PORTION OF
            FREDERICK COUNTY.

&&

EVENT NUMBER LWX2105797

CPB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
313 PM EDT WED SEP 01 2021

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

0311 PM     FLASH FLOOD      3 NNE WOODSBORO         39.57N  77.29W
09/01/2021                   FREDERICK          MD   911 CALL CENTER

            WATER RESCUE NEAR INTERSECTION OF HINEY ROAD AND LEGORE
            ROAD.

&&

EVENT NUMBER LWX2105798

CPB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
343 PM EDT WED SEP 01 2021

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

0218 PM     FLOOD            1 SE HARPERS FERRY      39.32N  77.73W
09/01/2021                   JEFFERSON          WV   911 CALL CENTER

            ROCKSLIDE CLOSED CHESNUT HILL ROAD NEAR ROUTE 340.

&&

EVENT NUMBER LWX2105799

CPB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
351 PM EDT WED SEP 01 2021

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

0324 PM     FLASH FLOOD      FREDERICK               39.43N  77.42W
09/01/2021                   FREDERICK          MD   911 CALL CENTER

            AT LEAST SIX SWIFT WATER RESCUES IN FREDERICK COUNTY.

&&

EVENT NUMBER LWX2105800

CPB