1 heat, as filed by the National Weather Service.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
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 20, 10:20 AM EST, 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1120 AM EDT FRI AUG 20 2004 .UPDATE: WATER VAPOR LOOP SHOWS AN UPPER LEVEL RIDGE OVER THE SOUTHEAST CONUS...WITH AN UPPER LEVEL TROUGH CENTERED OVER THE HUDSON BAY. SEVERAL WAVES ARE NOTED EMBEDDED WITHIN THE MEAN FLOW BETWEEN THESE TWO SYSTEMS...WITH THE FIRST WEAK WAVE UPSTREAM CURRENTLY MOVING THROUGH THE TENNESSEE VALLEY. ACARS 400-250MB WIND SPEED OBSERVATIONS SHOW THE NORTHERN STREAM 100KT JET ACROSS THE GREAT LAKES...WHILES A SOUTHERN STREAM JET EXTENDS NORTHEAST FROM SOUTHWEST TEXAS INTO THE TENNESSEE VALLEY. SURFACE ANALYSIS PLACES A 1011MB CYCLONE NEAR SAINT LOUIS ALONG THE STALLED BOUNDARY WHICH EXTENDS ACROSS THE EASTERN GREAT LAKES. TWO ADDITIONAL COLD FRONTS TRAIL BEHIND IN THE UPPER MIDWEST AND SOUTHERN CANADA. BOTH THE 12Z SURFACE ANALYSIS AND 14Z MESOANALYSIS PLACES A SUBTLE SURFACE TROUGH EXTENDING EAST FROM THE SURFACE LOW THROUGH THE TENNESSEE VALLEY. THIS SURFACE FEATURE WHICH CORRELATES WELL WITH THE WEAK MIDLEVEL WAVE WILL CONTINUE TO MOVE NORTHEAST INTO THE NORTHERN MID ATLANTIC REGION. PLENTY OF INSTABILITY EXPECTED THIS AFTERNOON. WHEN THE 12Z IAD SOUNDING IS ADJUSTED FOR A SURFACE TEMPERATURE OF 91 AND DEWPOINT OF 71...SURFACE BASED CAPE IS EXPECTED BETWEEN 2500 AND 3500 J/KG...AND MIXED LAYER CAPE BETWEEN 1800 AND 2300 J/KG. SATELLITE SOUNDING OBSERVED LIFTED INDICES ARE CURRENTLY RUNNING -4 TO -6C WEST OF THE BLUE RIDGE. CURRENTLY LACKING SURFACE CONVERGENCE ACROSS THE FORECAST AREA...WHILE LOW LEVEL WINDS MAY BE TOO HIGH TO PROMOTE TERRAIN CIRCULATION STORMS. HOWEVER...EXPECT STORMS TO APPROACH BOTH THE NORTHWEST (FROM DEVELOPMENT ALONG THE FRONTAL BOUNDARY) AND SOUTHWEST (FROM DEVELOPMENT ASSOCIATED WITH THE WEAK TENNESSEE VALLEY MIDLEVEL WAVE) FORECAST AREA LATE THIS AFTERNOON. CANT RULE OUT AN ISOLATED STORM FURTHER EAST DUE TO THE INSTABILITY AND CONVERGENCE OFFERED BY A POSSIBLE BAY BREEZE. FORECAST HODOGRAPHS REVEAL SIMILAR SHEAR COMPARED TO YESTERDAY. INVERTED-V SOUNDING (DESPITE DEWPOINTS NEAR 70F) MAY ALLOW SOME STORMS TO PRODUCE GUSTY TO DAMAGING WINDS. WHILE WET BULB ZERO VALUES ARE NEAR 10.5 KFT...HAIL WILL BE CONFINED ANY STORMS WITH SUSTAINED CORES ABOVE 25 KFT (-20C LEVEL). HEAT INDICES WILL APPROACH 100 DEGREES DURING THE AFTERNOON...AND HAVE ISSUED A SPECIAL WEATHER STATEMENT (WBCSPSLWX) TO DISCUSS THIS ALONG WITH THE AFTERNOON STORMS. && .AVIATION: LIGHT HAZE WILL PERSIST FOR A FEW HOURS WHILE CUMULUS DEVELOP AT 5KFT. LATE THUNDERSTORMS WILL BE MOST PERSISTENT ACROSS THE FAR NORTHWEST AND SOUTHWEST ZONES...VICINITY THUNDERSTORMS WILL COVER THIS RISK ACROSS THE TERMINAL SITES AS THERE WILL BE A LACK OF A BROADER SCALE CONVERGENCE AREA. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && ROGOWSKI
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1035 AM EDT FRI AUG 20 2004 DCZ001-MDZ002>007-009>011-013-014-016>018-VAZ021-025>031-036>042- 050>057-WVZ048>055-211600- ALBEMARLE VA-ALLEGANY MD-ANNE ARUNDEL MD- ARLINGTON/FALLS CHURCH/ALEXANDRIA VA-AUGUSTA VA-BERKELEY WV- CALVERT MD-CARROLL MD-CHARLES MD-CLARKE VA-CULPEPER VA- DISTRICT OF COLUMBIA DC-FAIRFAX VA-FAUQUIER VA-FREDERICK VA- FREDERICK MD-GRANT WV-GREENE VA-HAMPSHIRE WV-HARDY WV-HARFORD MD- HIGHLAND VA-HOWARD MD-JEFFERSON WV-KING GEORGE VA-LOUDOUN VA- MADISON VA-MINERAL WV-MONTGOMERY MD-MORGAN WV-NELSON VA- NORTHERN BALTIMORE MD-ORANGE VA-PAGE VA-PENDLETON WV- PRINCE GEORGES MD-PRINCE WILLIAM/MANASSAS/MANASSAS PARK VA- RAPPAHANNOCK VA-ROCKINGHAM VA-SHENANDOAH VA-SOUTHERN BALTIMORE MD- SPOTSYLVANIA VA-ST. MARYS MD-STAFFORD VA-WARREN VA-WASHINGTON MD- 1035 AM EDT FRI AUG 20 2004 THIS HAZARDOUS WEATHER OUTLOOK IS FOR MARYLAND WEST OF THE CHESAPEAKE BAY AND EAST OF GARRETT COUNTY...EASTERN WEST VIRGINIA...NORTHERN AND CENTRAL VIRGINIA AND WASHINGTON DC. .DAY ONE...TEMPERATURES IN THE 90S WHEN COMBINED WITH AN ABUNDANT AMOUNT OF MOISTURE...WILL ALLOW HEAT INDICES TO APPROACH 100 DEGREES THIS AFTERNOON. THIS HUMIDITY WILL ALSO FUEL ISOLATED TO SCATTERED THUNDERSTORMS FROM MID AFTERNOON THROUGH THE EVENING HOURS. A FEW OF THESE STORMS MAY BECOME STRONG TO SEVERE...AND MAY PRODUCE GUSTY TO DAMAGING WINDS...HEAVY RAIN AND HAIL. .DAYS TWO THROUGH SEVEN... SCATTERED THUNDERSTORMS CAN BE EXPECTED INTO SATURDAY. OTHERWISE NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED LATE THIS AFTERNOON OR THIS EVENING. ROGOWSKI
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 755 AM EDT FRI AUG 20 2004 DCZ001-MDZ002>007-009>011-013-014-016>018-VAZ021-025>031-036>042- 050>057-WVZ048>055-202200- ALBEMARLE VA-ALLEGANY MD-ANNE ARUNDEL MD- ARLINGTON/FALLS CHURCH/ALEXANDRIA VA-AUGUSTA VA-BERKELEY WV- CALVERT MD-CARROLL MD-CHARLES MD-CLARKE VA-CULPEPER VA- DISTRICT OF COLUMBIA DC-FAIRFAX VA-FAUQUIER VA-FREDERICK VA- FREDERICK MD-GRANT WV-GREENE VA-HAMPSHIRE WV-HARDY WV-HARFORD MD- HIGHLAND VA-HOWARD MD-JEFFERSON WV-KING GEORGE VA-LOUDOUN VA- MADISON VA-MINERAL WV-MONTGOMERY MD-MORGAN WV-NELSON VA- NORTHERN BALTIMORE MD-ORANGE VA-PAGE VA-PENDLETON WV- PRINCE GEORGES MD-PRINCE WILLIAM/MANASSAS/MANASSAS PARK VA- RAPPAHANNOCK VA-ROCKINGHAM VA-SHENANDOAH VA-SOUTHERN BALTIMORE MD- SPOTSYLVANIA VA-ST. MARYS MD-STAFFORD VA-WARREN VA-WASHINGTON MD- 755 AM EDT FRI AUG 20 2004 ...HOT AND HUMID CONDITIONS THIS AFTERNOON... TEMPERATURES IN THE 90S WHEN COMBINED WITH AN ABUNDANT AMOUNT OF MOISTURE...WILL ALLOW HEAT INDICES TO APPROACH 100 DEGREES THIS AFTERNOON. THOSE WHO WILL BE OUTSIDE DURING THE AFTERNOON HOURS SHOULD TAKE FREQUENT BREAKS WITHIN AN AIR CONDITIONED BUILDING. THIS HUMIDITY WILL ALSO FUEL ISOLATED TO SCATTERED THUNDERSTORMS FROM MID AFTERNOON THROUGH THE EVENING HOURS. A FEW OF THESE STORMS MAY BECOME STRONG TO SEVERE...AND MAY PRODUCE GUSTY TO DAMAGING WINDS...HEAVY RAIN AND HAIL. STAY TUNED TO NOAA WEATHER RADIO AND OTHER LOCAL MEDIA FOR FURTHER DETAILS OR UPDATES. ROGOWSKI
The national radar mosaic for the moment the first event began.
1 heat. Local standard time, as filed.
Heat indices at College Park rose to 105 degrees on August 2oth.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2004Every state in 2004This day in weather historyWarnings in Maryland, August 2004
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 2026-09-24. Each event’s entry at NCEI: 5421792.