Alert archive / Pennsylvania / Areal Flood Advisories in 2008

Areal Flood Advisory 7, NWS Philadelphia/Mount Holly

July 23, 2008Bucks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jul 23, 2008, 4:23 AM EDT for Bucks County, Chester County, Montgomery County, Pennsylvania. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued
Jul 23, 2008, 4:23 AM EDT (08:23 UTC)
Expired
Jul 23, 2008, 7:30 AM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Bucks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 88 km from the middle of the area, began a volume at 08:24 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 8.4 hours before the alert went out and 218 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Washington/Dulle, VA at 00:00Z on 2008-07-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 934 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 00:00Z on 2008-07-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 81 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
934 J/kg
Mixed-layer CIN
-29 J/kg
Mixed-layer LCL
1560 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
81 m²/s²
0-3 km storm-relative helicity
224 m²/s²
Significant tornado parameter
0.4
Supercell composite
5.6

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Philadelphia/Mount Holly wrote its last area forecast discussion before this areal flood advisory went out at Jul 23, 3:50 AM EDT, 33 minutes earlier.

Area forecast discussion, Jul 23, 3:50 AM EDT, 33 minutes before
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Hazardous weather outlook, Jul 22, 2:11 PM EDT, 14 hours 12 minutes before
HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
211 PM EDT TUE JUL 22 2008

DEZ002-003-MDZ008-012-015-019-020-NJZ001-007>010-012-013-016-020>023-
027-PAZ054-055-060>062-231815-
KENT-INLAND SUSSEX-CECIL-KENT MD-QUEEN ANNES-TALBOT-CAROLINE-SUSSEX-
WARREN-MORRIS-HUNTERDON-SOMERSET-MIDDLESEX-WESTERN MONMOUTH-SALEM-
OCEAN-CUMBERLAND-ATLANTIC-CAPE MAY-SOUTHEASTERN BURLINGTON-CARBON-
MONROE-BERKS-LEHIGH-NORTHAMPTON-
211 PM EDT TUE JUL 22 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL DELAWARE...SOUTHERN
DELAWARE...NORTHEAST MARYLAND...CENTRAL NEW JERSEY...NORTHERN NEW
JERSEY...NORTHWEST NEW JERSEY...SOUTHERN NEW JERSEY...EAST CENTRAL
PENNSYLVANIA AND NORTHEAST PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED THUNDERSTORMS COULD BECOME SEVERE LATE TODAY OR TONIGHT
AND THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A
SLIGHT RISK FOR SEVERE THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

VERY HEAVY RAINFALL IS POSSIBLE WEDNESDAY AND WEDNESDAY NIGHT TIME
FRAME. RAINFALL RATES IN EXCESS OF 2 INCHES AN HOUR ARE POSSIBLE.
ALSO, THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A
SLIGHT RISK FOR SEVERE THUNDERSTORMS WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

DEZ001-NJZ015-017>019-PAZ067>071-231815-
NEW CASTLE-MERCER-GLOUCESTER-CAMDEN-NORTHWESTERN BURLINGTON-CHESTER-
MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA-
211 PM EDT TUE JUL 22 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN DELAWARE...CENTRAL
NEW JERSEY...SOUTHERN NEW JERSEY AND SOUTHEAST PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

TEMPERATURES WILL BE HOT TODAY WITH HIGHS IN THE LOWER AND MIDDLE
90S. THE HEAT INDEX IS EXPECTED TO PEAK AROUND 97 DEGREES.

GIVEN THE LENGTH OF THE PERIOD OF HEAT, IT STILL IS WISE TO BE
CAREFUL AND TO TAKE PRECAUTIONS AGAINST THE HEAT, ESPECIALLY IN
THE HIGHLY URBANIZED AREAS OF THE DELAWARE VALLEY. REMEMBER TO PAY
PARTICULAR ATTENTION TO THE ELDERLY, THE VERY YOUNG, THE INFIRM,
AND ANIMALS THAT DEPEND UPON US.

ISOLATED THUNDERSTORMS COULD BECOME SEVERE LATE TODAY OR TONIGHT
AND THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A
SLIGHT RISK FOR SEVERE THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

VERY HEAVY RAINFALL IS POSSIBLE WEDNESDAY AND WEDNESDAY NIGHT TIME
FRAME. RAINFALL RATES IN EXCESS OF 2 INCHES AN HOUR ARE POSSIBLE.
ALSO, THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A
SLIGHT RISK FOR SEVERE THUNDERSTORMS WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

DEZ004-NJZ014-024-025-231815-
DELAWARE BEACHES-EASTERN MONMOUTH-ATLANTIC COASTAL CAPE MAY-
COASTAL ATLANTIC-
211 PM EDT TUE JUL 22 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHERN DELAWARE...CENTRAL
NEW JERSEY AND SOUTHERN NEW JERSEY.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED THUNDERSTORMS COULD BECOME SEVERE LATE TODAY OR TONIGHT
AND THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A SLIGHT
RISK FOR SEVERE THUNDERSTORMS.

THERE WILL BE A MODERATE RISK FOR RIP CURRENTS TODAY AND TONIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

VERY HEAVY RAINFALL IS POSSIBLE WEDNESDAY AND WEDNESDAY NIGHT TIME
FRAME. RAINFALL RATES IN EXCESS OF 2 INCHES AN HOUR ARE POSSIBLE.
ALSO, THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A
SLIGHT RISK FOR SEVERE THUNDERSTORMS WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

ANZ430-431-450>455-NJZ026-231815-
DELAWARE BAY WATERS NORTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
DELAWARE BAY WATERS SOUTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
COASTAL WATERS FROM SANDY HOOK TO MANASQUAN INLET NJ OUT 20 NM-
COASTAL WATERS FROM MANASQUAN INLET TO LITTLE EGG INLET NJ OUT 20 NM-
COASTAL WATERS FROM LITTLE EGG INLET TO GREAT EGG INLET NJ OUT 20 NM-
COASTAL WATERS FROM GREAT EGG INLET TO CAPE MAY NJ OUT 20 NM-
COASTAL WATERS FROM CAPE MAY NJ TO CAPE HENLOPEN DE OUT 20 NM-
COASTAL WATERS FROM CAPE HENLOPEN TO FENWICK ISLAND DE OUT 20 NM-
COASTAL OCEAN-
211 PM EDT TUE JUL 22 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL
WATERS...DELAWARE BAY WATERS AND SOUTHERN NEW JERSEY.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED THUNDERSTORMS COULD BECOME SEVERE LATE TODAY OR TONIGHT
AND THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A SLIGHT
RISK FOR SEVERE THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER A SLIGHT
RISK FOR SEVERE THUNDERSTORMS WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

In the hours before

Special weather statement, Jul 22, 11:14 PM EDT, 5 hours 9 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1114 PM EDT TUE JUL 22 2008

MDZ008-012-230445-
CECIL MD-KENT MD-
1114 PM EDT TUE JUL 22 2008

...A STRONG THUNDERSTORM WILL AFFECT CECIL AND KENT COUNTIES IN
MARYLAND...

AT 1106 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 28 MILES NORTHWEST OF CENTERVILLE...MOVING
NORTHEAST AT 28 MPH. THE THUNDERSTORM WILL BE NEAR LANGFORD AROUND
1130 PM...NEWTOWN...CHESTERTOWN AROUND 1145 PM...BETTERTON AROUND
MIDNIGHT...WOODLAWN...PERRYVILLE AROUND 1215 AM...LOMBARD AND ZION
AROUND 1230 AM.

WIND GUSTS TO 40 MPH AS WELL AS TORRENTIAL DOWNPOURS ARE POSSIBLE
WITH THIS STORM.

ALSO, A GUST FRONT MAY COME OUT FROM THE STORM AND AFFECT AREAS IN
KENT AND CECIL COUNTIES MARYLAND THAT ARE NOT DIRECTLY IN THE PATCH
OF THE STORM.

EXPECT INTENSE LIGHTNING FROM THIS STORM. DO NOT SEEK SHELTER UNDER
TREES WHEN LIGHTNING THREATENS...MOVE INDOORS WHEN A THUNDERSTORM
APPROACHES.

RNS
Special weather statement, Jul 22, 11:46 PM EDT, 4 hours 37 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1146 PM EDT TUE JUL 22 2008

PAZ067-230515-
CHESTER PA-
1146 PM EDT TUE JUL 22 2008

...STRONG THUNDERSTORMS WILL AFFECT CHESTER COUNTY...

AT 1142 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS OVER SOUTHERN LANCASTER COUNTY...MOVING
NORTHEAST AT 25 MPH. THE THUNDERSTORMS WILL BE NEAR OXFORD...GLEN
ROY AROUND MIDNIGHT...AVONDALE AROUND 1215 AM...SOUTH COATESVILLE
AROUND 1230 AM...AND DOWNINGTOWN AROUND 1245 AM.

VERY HEAVY RAIN WILL FALL FROM THESE STORMS...AND WILL CAUSE WATER TO
POND ON ROADS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

WIND GUSTS TO 40 MPH ARE POSSIBLE.

EXPECT INTENSE LIGHTNING FROM THIS STORM. DO NOT SEEK SHELTER UNDER
TREES WHEN LIGHTNING THREATENS...MOVE INDOORS WHEN A THUNDERSTORM
APPROACHES.

RNS
Special weather statement, Jul 23, 12:08 AM EDT, 4 hours 15 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1208 AM EDT WED JUL 23 2008

DEZ001-MDZ008-012-NJZ016>019-PAZ068-070-071-230545-
CAMDEN NJ-CECIL MD-DELAWARE PA-GLOUCESTER NJ-KENT MD-MONTGOMERY PA-
NEW CASTLE DE-NORTHWESTERN BURLINGTON NJ-PHILADELPHIA PA-SALEM NJ-
1208 AM EDT WED JUL 23 2008

...STRONG THUNDERSTORMS WILL AFFECT BURLINGTON...CAMDEN...CECIL...
DELAWARE...GLOUCESTER...KENT...MONTGOMERY...NEW CASTLE...
PHILADELPHIA AND SALEM COUNTIES...

AT MIDNIGHT EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS OVER NORTHEAST MARYLAND...MOVING NORTHEAST
AROUND 25 MPH. THE THUNDERSTORMS WILL HEAD ACROSS NORTHERN DELAWARE
INTO SOUTHWEST NEW JERSEY AND SOUTHEAST PENNSYLVANIA THROUGH 145 AM.

VERY HEAVY RAIN WILL FALL FROM THESE STORMS...AND COULD CAUSE WATER
TO POND ON ROADS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

WIND GUSTS TO 40 MPH ARE ALSO POSSIBLE.

EXPECT FREQUENT LIGHTNING FROM THE STORMS. DO NOT SEEK SHELTER UNDER
TREES WHEN LIGHTNING THREATENS...MOVE INDOORS WHEN A THUNDERSTORM
APPROACHES.

RNS

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 23, 3:02 AM EDTSpecial Marine WarningPHI58 min
Jul 23, 3:51 AM EDTFlash Flood WatchPHIAtlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 10 more25 hr
Jul 23, 2:44 PM EDTSevere Thunderstorm WarningPHICumberland, Salem46 min
Jul 23, 2:55 PM EDTSevere Thunderstorm WarningPHIMercer35 min
Jul 23, 2:58 PM EDTSevere Thunderstorm WarningPHIHunterdon47 min
Jul 23, 3:26 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer, Somerset64 min
Jul 23, 3:30 PM EDTSevere Thunderstorm WarningPHIGloucester, Salem60 min
Jul 23, 4:03 PM EDTSevere Thunderstorm WarningPHIMiddlesex, Morris, Somerset57 min
Jul 23, 4:09 PM EDTTornado WarningPHIMiddlesex, Somerset36 min
Jul 23, 4:51 PM EDTAreal Flood WarningPHIMiddlesex, Somerset105 min
Jul 23, 5:03 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer, Somerset57 min
Jul 23, 5:13 PM EDTSevere Thunderstorm WarningPHIBurlington, Mercer, Middlesex, Monmouth, Somerset62 min
Jul 23, 7:00 PM EDTSevere Thunderstorm WarningPHIGloucester, Salem60 min
Jul 23, 7:10 PM EDTSevere Thunderstorm WarningPHIMiddlesex, Morris, Somerset35 min
Jul 23, 7:48 PM EDTSevere Thunderstorm WarningPHIBurlington, Camden, Gloucester57 min
Jul 23, 3:58 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery62 min
Jul 23, 4:27 PM EDTSevere Thunderstorm WarningPHIChester, Delaware38 min
Jul 23, 4:47 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton58 min
Jul 23, 12:30 AM EDTSevere Thunderstorm WarningPHICecil45 min
Jul 23, 1:11 AM EDTSevere Thunderstorm WarningPHICecil64 min
Jul 23, 6:11 PM EDTSevere Thunderstorm WarningPHICaroline, Queen Anne's, Talbot64 min
Jul 23, 7:14 PM EDTSevere Thunderstorm WarningPHICecil, Kent, Queen Anne's61 min

Nearby

Areal Flood Advisories in Pennsylvania, 2008Every areal flood advisory in 2008

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.