A very slow moving frontal system came through the region on the 27th. Moisture ahead of the front was plentiful.
Every event with a place to put it; 5 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 episode as NWS LWX wrote it up.
A very slow moving frontal system came through the region on the 27th. Moisture ahead of the front was plentiful. Two to five inches of rain produced wide spread flash flooding in Montgomery and Prince Georges Counties.In Montgomery County the areas hardest hit were Chevy Chase, Bethesda, Silver Spring and Colesville. Several people were trapped in cars prompting numerous water rescues. In Silver Spring, on Sligo Creek Parkway near New Hampshire Avenue, several vehicles were halfway submerged by water. Cars were also stranded in Rock Creek Park and in low lying areas near the Potomac River. Four feet of water flooded the automatic train control room in Silver Spring. The Carol Avenue Bridge was damaged by flooding and the road was closed. Several structures were also struck by lightning.In Prince Georges County the communities hardest hit were Delphi, Beltsville and Laurel. Drivers were rescued from flooded vehicles at New Hampshire Avenue and Piney Branch Road. Five families were evacuated from an apartment in Laurel because water flooded the building. Flights to all three of the Washington region's major airports were delayed or cancelled.
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 Jul 27, 10:00 AM EST, 7 hours 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1100 AM EDT TUE JUL 27 2004 .SHORT TERM...TODAY AND TNGT... ALL PRODUCTS RELEASED. I WL CONFESS...MY ABILITY TO WRITE DAY AFTR DAY ABT LOW CLDS/DAMPNESS HAS REACHED ITS LIMIT. IVE GOT NOTHING MORE TO SAY. AS I THOUGHT LAST JUL WAS WET I LOOKED AT DCA FOR THIS JUL VS JUL 03. THRU 7/26 PCPN TOTALS ARE ABT THE SAME 4.8. ITS RAINED MEASURABLY ON 9 DAYS SO FAR THIS JUL...ECLIPSED BY THE 13 IT RAINED ON LAST. NEITHER HERE NOR THERE...JUST A FACTOID. AM LVG THE FFA IN EFFECT THRU 6 PM...ALTHO ATTM NOT TERRIBLY EXCITED ABT IT. IFLOWS GAGES IN ERN WV HAVE RECORDED NOTHING IN THE LAST 6 HRS. THE BAND OF HVIER PCPN IS BARELY MAKING ANY EWD PROGRESS. WOODY && .LONG TERM...WED AND BEYOND... BASIC MDL AGREEMENT ON TAKING H5 CLSD LOW OVR GRTLKS NEWD WED-THU WHILE OPENING IT UP AND WEAKENING IT. RSLTNT PTTN ACRS NOAM CERTAINLY DOES NOT RESEMBLE SUMMER. ATLC RDG PARKED RATHER FAR TO THE N...NOT IN ITS TYPICAL SUBTROPICAL POSN. ANOTHR DEEP H5 L/WV TROF...W/ A CLSD LOW OF ITS OWN OVER MANITOBA...SLICING DWN THE PLAINS. CDFNT RUNS INTO ATLC RDG...STALLS OUT...AND WEAKENS ALNG ERN SEABRD WED-THU...SUPPORTED BY GOOD SFC-H5 CONFLUENCE AND SUPPORT OF RRQ OF UPR JET. THIS FLOW WL SUPPLY BOTH ATLC AND GLFMEX MSTR. SO...HAD TO TAKE A SLIGHTLY MORE PESSIMISTIC APPROACH TO FCST. ETA/GFS SIMILAR IN QPF FIELDS...THO THEIR RESPECTIVE MOS PRODUCTS DEPICT SOME VARIATION BY 4TH-5TH PDS. FCST GRIDS WED NGT-THU WL SPLIT THE DIFF...ONLY BECUASE BLV THAT THERE IS THE RISK OF PCP...BUT RECENT HISTORY WUD SUGGEST MORE CAUTION THAN MAV...SPCLY CONSIDERING ITS WET BIAS. ALSO...TRIED TO DELINIATE VARIATION BTWN SRN MD /WET/ AND PTMC HIGHLANDS...WHICH LIKLEY WL BE MAJORITY INFLUENCED BY SFC HIPRES BLDG FM GRTLKS. MADE A FEW TEMP CHGS NXT CPL OF DAYS TO LINE UP W/ PCPN CHGS... DECREASING MAXT WED AND THU...AND INCR MIN-T EACH NGT...SPLCY IN THE E WHERE DEWPTS WL REMAIN ON THE HIGH SIDE /UPR 60S TO NEAR 70/. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...FFA TODAY DCZ001 MD...FFA TODAY MDZ002>007...MDZ009>011. VA...FFA TODAY VAZ021...VAZ025>031...VAZ036>042...VAZ050>056. WV...FFA TODAY WVZ048>055. MARINE...NONE. && LONG TERM...HTS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1127 AM EDT TUE JUL 27 2004 DCZ001-MDZ002>007-009>011-013-014-016>018-VAZ021-025>031-036>042- 050>057-WVZ048>055-280800- 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- 1127 AM EDT TUE JUL 27 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... SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY AS A COLD FRONT SLOWLY ADVANCES FROM THE WEST. WITH ABUNDANT MOISTURE IN THE ATMOSPHERE...HEAVY RAINFALL WILL BE POSSIBLE THROUGH THIS EVENING. SOME OF THE HEAVIER SHOWERS AND THUNDERSTORMS COULD PRODUCE RAINFALL OF UP TO 3 INCHES IN A SHORT PERIOD OF TIME. THIS WOULD BE SUFFICIENT TO CAUSE FLOODING OF STREAMS...CREEKS AND URBAN AREAS. .DAYS TWO THROUGH SEVEN... HEAVY RAINFALL WILL BE POSSIBLE EAST OF INTERSTATE 95 ON WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED
The national radar mosaic for the moment the first event began.
5 flash flood. Local standard time, as filed.
Several roads closed along Highway 7 and 136.
Several roads closed around the county.
Creeks and streets flooded.
Streets flooded with water covering roadways.
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, July 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: 5418011, 5418012, 5418013, 5418014, 5418015.