A cold front approached the area on the 31st. Hot and humid conditions ahead of the front led to an unstable atmosphere.
Every event with a place to put it. 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 cold front approached the area on the 31st. Hot and humid conditions ahead of the front led to an unstable atmosphere. A few thunderstorms developed due to the heating of the day and the approaching cold front. Some thunderstorms became severe with strong winds due to stronger shear from an upper-level trough overhead.
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 31, 1:47 PM EST, 33 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 247 PM EDT Sun Jul 31 2016 .SYNOPSIS... An area of weak low pressure will track eastward across the area tonight and Monday. A weak cold front will move southeastward late Monday as the low moves offshore. High pressure will build in from the north during the middle of the week. && .NEAR TERM /THROUGH TONIGHT/... Thunderstorms developed late this morning in the Appalachians, in an airmass that is more unstable than the coastal plain. Effective shear is about comparable throughout the region...30-35 kt. However, a belt of slightly higher westerlies (35-40 kt) resides across southern West Virginia. Would anticipate that shear zone to traverse central Virginia late this afternoon. Otherwise, expect the evolution to be mountain storms slowly tracking east through the afternoon and into the evening. That is what the database reflects, with slightly higher numbers in Virginia due to their proximity to higher shear. Have taken note of the surface wind direction, which is more southwesterly vs westerly. Thus, warm moist air is still being advected north, which would support storms development. However, the precipitable water plume is off southeast Virginia, and CAPE values are about half of yesterday. Therefore, coverage and intensity should be less. Believe that there will be a diurnal weakening after dark. However, that will partly be driven by the wind shift/convergent axis, which doesn't push to the Eastern Shore until after midnight. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Tomorrow's synoptic setup will be similar to today's, just displaced a bit to the east. The trof axis is still to the west of the forecast area, with the weak surface low atop us. Therefore, the focus for scattered PoPs will be east of the Blue Ridge. Since moisture depth will be less, am keeping PoPs in the 30-40 percent range. Same thing goes for Tuesday. Drier air will advect east as the trof axis should have swung through, permitting northwest flow to shunt the warm, unstable air mass further to the east. Am hopeful that will translate to a seasonable, dry day. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Mainly dry on Wednesday as heights begin to rise. Surface warm front lifts near our region on Thursday... upper disturbance moves through on Friday and cold front approaches on Saturday... and lingers into Sunday. All these allowing for more showers and thunderstorms over our CWA. High temperatures will be in the upper 80s to the low 90s. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... A line of thunderstorms beginning to develop in the mountains. Believe this axis will gradually travel east this afternoon and evening. Brief, local IFR restrictions will result. TAFs have a more generic VCTS afternoon into early evening. Will need to employ amendments as precise timing becomes clear. Storms should exit the region by midnight. Residual low level moisture may permit fog development. Am uncertain to the areal coverage, which will partly be determined by sky cover. At this point, have placed fog in typical mountain valleys, which clips MRB/CHO to borderline MVFR/IFR vsbys. There will be an opportunity for thunderstorms to redevelop Monday, especially in the afternoon. The focus would have shifted to the east, emphasizing the metros. Confidence in areal coverage too limited for a TAF mention at this time. VFR should prevail by Tuesday. Mainly VFR conditions expected for Wednesday through Friday... with some showers and thunderstorms possible... bringing periods of sub-VFR conditions. && .MARINE... Winds on the waters 10 kt or less. Any higher winds tonight or tomorrow would be in vicinity of thunderstorms. Marine Warnings possible later today into tonight. Winds should become northwesterly Monday night or Tuesday. Jury still out whether the gradient or mixing would be sufficient for higher sustained winds or gusts. At this point, will side on not. Sub-SCA conditions expected through the end of the week. Showers and thunderstorms possible over the waters during this period could bring gusty winds. && .TIDES/COASTAL FLOODING... Water level departures are returning closer to normal...and presently are near a half-foot. Will still need to keep an eye on Annapolis, which will come real close to touching the minor threshold overnight. Otherwise, tides should peak in the caution stage at worst. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...ADS/HTS NEAR TERM...HTS SHORT TERM...HTS LONG TERM...IMR AVIATION...HTS/IMR MARINE...HTS/IMR TIDES/COASTAL FLOODING...HTS/JE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1206 PM EDT SUN JUL 31 2016 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-011000- 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-SOUTHERN BALTIMORE-PRINCE GEORGES- ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-SOUTHEAST HARFORD- PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX- ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA- KING GEORGE- 1206 PM EDT SUN JUL 31 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF COLUMBIA. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-011000- WASHINGTON-FREDERICK MD-CARROLL-NORTHERN BALTIMORE- EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY- NORTHWEST MONTGOMERY-CENTRAL AND SOUTHEAST MONTGOMERY- NORTHWEST HOWARD-CENTRAL AND SOUTHEAST HOWARD-NORTHWEST HARFORD- AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE- NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-ORANGE-CULPEPER- NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND- EASTERN HIGHLAND-WESTERN LOUDOUN-EASTERN LOUDOUN- NORTHERN VIRGINIA BLUE RIDGE-CENTRAL VIRGINIA BLUE RIDGE- HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-HARDY-WESTERN GRANT- EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-WESTERN PENDLETON- EASTERN PENDLETON- 1206 PM EDT SUN JUL 31 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA... NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND WITH THE EXCEPTION OF GARRETT COUNTY. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY 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
1130 AM EDT SUN JUL 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0818 PM FLASH FLOOD 2 SE CLARKSBURG 39.22N 77.26W
07/30/2016 MONTGOMERY MD EMERGENCY MNGR
10 IN OF FLOWING WATER NEAR 22300 N FREDERICK RD
&&
EVENT NUMBER LWX1604631
IMRPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
144 PM EDT SUN JUL 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0748 PM FLOOD BOYDS 39.18N 77.31W
07/30/2016 MONTGOMERY MD OTHER FEDERAL
THE STREAM GAUGE ON TEN MILE CREEK IN BOYDS EXCEEDED
THE 7 FOOT FLOOD STAGE BETWEEN 748 PM AND 902 PM. THE
PEAK WAS 8.55 FEET AT 815 PM.
&&
EVENT NUMBER LWX1604632
JEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
146 PM EDT SUN JUL 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0826 PM FLASH FLOOD CATONSVILLE 39.26N 76.74W
07/30/2016 BALTIMORE MD OTHER FEDERAL
THE STREAM GAUGE ON THE PATAPSCO RIVER AT CATONSVILLE
EXCEEDED THE 20 FOOT FLOOD STAGE FROM 826 PM TO JUST
AFTER MIDNIGHT. THE PEAK WAS 27.14 FEET AT 915 PM.
&&
EVENT NUMBER LWX1604633
JEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
151 PM EDT SUN JUL 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0912 PM FLASH FLOOD 2 E WOODLAWN 39.31N 76.72W
07/30/2016 BALTIMORE MD OTHER FEDERAL
THE STREAM GAUGE ON DEAD RUN IN FRANKLINTOWN EXCEEDED
THE 10 FOOT FLOOD STAGE BRIEFLY BETWEEN 912 PM AND 953
PM.
&&
EVENT NUMBER LWX1604634
JEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
156 PM EDT SUN JUL 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0848 PM FLASH FLOOD ARBUTUS 39.24N 76.69W
07/30/2016 BALTIMORE MD OTHER FEDERAL
THE STREAM GAUGE ON EAST BRANCH HERBERT RUN EXCEEDED
THE FLOOD STAGE BRIEFLY BETWEEN 848 PM AND 916 PM.
&&
EVENT NUMBER LWX1604635
JEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
158 PM EDT SUN JUL 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0855 PM FLASH FLOOD ELKRIDGE 39.20N 76.75W
07/30/2016 HOWARD MD OTHER FEDERAL
THE STREAM GAUGE ON THE PATAPSCO RIVER AT ELKRIDGE
RAPIDLY EXCEEDED THE FLOOD STAGE OF 15 FEET AT 855 PM.
IT REMAINED ABOVE FLOOD STAGE UNTIL AROUND 135 AM.
&&
EVENT NUMBER LWX1604636
JEThe Sterling radar (KLWX), 101 km away, was scanning. The volume nearest the first event began at 19:20 UTC.
3 thunderstorm wind. Local standard time, as filed.
Trees were down at Lake Anna State Park near cabin 1 and cabin 7.
A tree was down across Gable Farm Road near East Colonial Highway.
A tree was down in the 17000 block of Bridge View Court.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2016Every state in 2016This day in weather historyWarnings in Virginia, July 2016
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: 646482, 646480, 646481.