Heat in District of Columbia, August 12, 2021

Name: Heat in District of Columbia, August 12, 2021
Start: 2021-08-12T11:00
End: 2021-08-12T18:00
Location: District of Columbia

August 12, 2021 · NWS LWX · 1 event in 1 county or zone

A ridge of high pressure and southwesterly flow allowed heat and humidity to build across the region.

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS LWX wrote it up.

A ridge of high pressure and southwesterly flow allowed heat and humidity to build across the region.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Baltimore/Washington wrote its last area forecast discussion before the first event at Aug 12, 9:47 AM EST, 1 hour 13 minutes earlier.

Area forecast discussion, Aug 12, 9:47 AM EST, 1 hour 13 minutes before

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Hazardous weather outlook, Aug 12, 4:27 AM EST, 6 hours 33 minutes before

Hazardous Weather Outlook
National Weather Service Baltimore MD/Washington DC
527 AM EDT Thu Aug 12 2021

ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508-
VAZ052>057-130930-
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-
527 AM EDT Thu Aug 12 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...Today and Tonight

Isolated severe thunderstorms capable of producing damaging winds,
large hail, and isolated instances of flash flooding are possible
this afternoon and evening.

A Heat Advisory is in effect from noon until 8 PM this evening.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Heat index values of 100 to 109 degrees are likely during the
afternoon and early evening hours Friday.

Isolated severe storms along with isolated instances of flash
flooding are possible during the afternoon and evening hours
Friday through Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be necessary for Thursday afternoon to
evening.

MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508-
WVZ050>053-055-130930-
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-
527 AM EDT Thu Aug 12 2021

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

.DAY ONE...Today and Tonight

Isolated severe thunderstorms capable of producing damaging winds,
large hail, and isolated instances of flash flooding are possible
this afternoon and evening.

A Heat Advisory is in effect from noon until 8 PM this evening
for all of the outlooked area except for Augusta and Nelson
Counties in Virgina.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Heat index values of 100 to 107 likely during the afternoon and
early evening hours on Friday.

Isolated severe storms along with isolated instances of flash
flooding are possible during the afternoon and evening hours
Friday through Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be necessary for Thursday afternoon to
evening.

MDZ001-501-502-VAZ503-504-WVZ501>506-130930-
Garrett-Extreme Western Allegany-Central and Eastern Allegany-
Western Highland-Eastern Highland-Western Grant-Eastern Grant-
Western Mineral-Eastern Mineral-Western Pendleton-
Eastern Pendleton-
527 AM EDT Thu Aug 12 2021

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

.DAY ONE...Today and Tonight

Isolated severe thunderstorms capable of producing damaging winds,
large hail, and isolated instances of flash flooding are possible
this afternoon and evening.

A Heat Advisory is in effect from noon until 8 PM this evening for
eastern Mineral and Grant in WV and Allegany County in MD.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Isolated severe storms along with isolated instances of flash
flooding are possible during the afternoon and evening hours
Friday through Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be necessary for Thursday afternoon to
evening.

In the hours before

Local storm report, Aug 12, 9:08 AM EST, 1 hour 52 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1008 AM EDT THU AUG 12 2021

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

0422 PM     TSTM WND DMG     1 SW SHADWELL           38.00N  78.41W
08/11/2021                   ALBEMARLE          VA   FIRE DEPT/RESCUE

            TREE BLEW DOWN ON A HOUSE CAUSING STRUCTURAL DAMAGE IN
            THE 2000 BLOCK OF HILLVIEW COURT.

&&

EVENT NUMBER LWX2105267

CPB

Local storm report, Aug 12, 9:17 AM EST, 1 hour 43 minutes before

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Event by event

1 heat. Local standard time, as filed.

Heat, District of Columbia

When: August 12, 11:00 AM EST to 6:00 PM EST
Where: District of Columbia forecast zone
Reported by: AWOS

Heat indices rose to between 105 and 110 degrees.

What these are

Heat: Heat below excessive heat criteria that still caused deaths, injuries or significant impacts.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in District of Columbia in 2021 Every state in 2021 This day in weather history Warnings in District of Columbia, August 2021

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 983756.