Alert archive / Pennsylvania / Flash Flood Watches in 2015

Flash Flood Watch 6, NWS Philadelphia/Mount Holly

September 10, 20154 states

NWS Philadelphia/Mount Holly issued this flash flood watch at Sep 10, 2015, 12:34 PM EDT for 4 states. It took effect at Sep 10, 2015, 1:00 PM EDT. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued
Sep 10, 2015, 12:34 PM EDT (16:34 UTC)
In effect from
Sep 10, 2015, 1:00 PM EDT
Expired
Sep 10, 2015, 7:02 PM EDT
In force
6 hr
Issued by
NWS Philadelphia/Mount Holly
Flood severity
None

Counties Kent County, DE, New Castle County, DE, Cecil County, MD, Kent County, MD, Queen Anne's County, MD, Burlington County, NJ, Camden County, NJ, Gloucester County, NJ, Mercer County, NJ, Salem County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Delaware County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 87 km from the middle of the area, began a volume at 16:36 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 12:00Z, 4.6 hours before the alert went out and 199 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 12:00Z on 2015-09-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 58 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2015-09-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -4 square meters per square second.1939Sfc1 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
58 J/kg
Mixed-layer CIN
-85 J/kg
Mixed-layer LCL
843 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
-4 m²/s²
0-3 km storm-relative helicity
75 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

139 
WGUS61 KPHI 101634
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1234 PM EDT THU SEP 10 2015


DEZ001-002-MDZ008-012-015-NJZ015>019-PAZ060>062-070-071-101>106-
110000-
/O.NEW.KPHI.FF.A.0006.150910T1700Z-150911T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NEW CASTLE-KENT-CECIL-KENT MD-QUEEN ANNES-MERCER-SALEM-GLOUCESTER-
CAMDEN-NORTHWESTERN BURLINGTON-BERKS-LEHIGH-NORTHAMPTON-DELAWARE-
PHILADELPHIA-WESTERN CHESTER-EASTERN CHESTER-WESTERN MONTGOMERY-
EASTERN MONTGOMERY-UPPER BUCKS-LOWER BUCKS-
INCLUDING THE CITIES OF...WILMINGTON...DOVER...ELKTON...
CHESTERTOWN...CENTREVILLE...TRENTON...PENNSVILLE...GLASSBORO...
CAMDEN...CHERRY HILL...MOORESTOWN...MOUNT HOLLY...READING...
ALLENTOWN...BETHLEHEM...EASTON...MEDIA...PHILADELPHIA...
HONEY BROOK...OXFORD...WEST CHESTER...KENNETT SQUARE...
COLLEGEVILLE...POTTSTOWN...NORRISTOWN...LANSDALE...CHALFONT...
PERKASIE...MORRISVILLE...DOYLESTOWN
1234 PM EDT THU SEP 10 2015

...FLASH FLOOD WATCH IN EFFECT UNTIL 8 PM EDT THIS EVENING...

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY HAS ISSUED A

* FLASH FLOOD WATCH FOR PORTIONS OF DELAWARE...NORTHEAST 
  MARYLAND...NEW JERSEY AND PENNSYLVANIA...INCLUDING THE 
  FOLLOWING IN DELAWARE...KENT ...AND NEW CASTLE. IN NORTHEAST 
  MARYLAND...CECIL...KENT MD AND QUEEN ANNES. IN NEW JERSEY... 
  CAMDEN...GLOUCESTER...MERCER...NORTHWESTERN BURLINGTON AND 
  SALEM. IN PENNSYLVANIA...BERKS...DELAWARE...EASTERN CHESTER... 
  EASTERN MONTGOMERY...LEHIGH...LOWER BUCKS...NORTHAMPTON... 
  PHILADELPHIA...UPPER BUCKS...WESTERN CHESTER AND WESTERN 
  MONTGOMERY. 

* UNTIL 8 PM EDT THIS EVENING

* THUNDERSTORMS ARE EXPECTED TO CONTINUE TO DEVELOP AND MOVE OVER
  THE SAME AREAS IN SOUTHEASTERN PENNSYLVANIA...NORTHERN
  DELMARVA...AND PORTIONS OF SOUTHERN AND CENTRAL NEW JERSEY. MANY
  AREAS COULD SEE BETWEEN 1 TO 3 INCHES. POOR DRAINAGE AREAS WILL
  BE ESPECIALLY SUSCEPTIBLE TO FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO A RAPID RISE OF WATER TO DANGEROUS LEVELS. FLASH FLOODING IS A
VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$
1 follow-up statement
741 
WGUS61 KPHI 102302
FFAPHI

FLOOD WATCH
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
702 PM EDT THU SEP 10 2015

DEZ001-002-MDZ008-012-015-NJZ015>019-PAZ060>062-070-071-101>106-
110015-
/O.CAN.KPHI.FF.A.0006.000000T0000Z-150911T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NEW CASTLE-KENT-CECIL-KENT MD-QUEEN ANNES-MERCER-SALEM-GLOUCESTER-
CAMDEN-NORTHWESTERN BURLINGTON-BERKS-LEHIGH-NORTHAMPTON-DELAWARE-
PHILADELPHIA-WESTERN CHESTER-EASTERN CHESTER-WESTERN MONTGOMERY-
EASTERN MONTGOMERY-UPPER BUCKS-LOWER BUCKS-
INCLUDING THE CITIES OF...WILMINGTON...DOVER...ELKTON...
CHESTERTOWN...CENTREVILLE...TRENTON...PENNSVILLE...GLASSBORO...
CAMDEN...CHERRY HILL...MOORESTOWN...MOUNT HOLLY...READING...
ALLENTOWN...BETHLEHEM...EASTON...MEDIA...PHILADELPHIA...
HONEY BROOK...OXFORD...WEST CHESTER...KENNETT SQUARE...
COLLEGEVILLE...POTTSTOWN...NORRISTOWN...LANSDALE...CHALFONT...
PERKASIE...MORRISVILLE...DOYLESTOWN
702 PM EDT THU SEP 10 2015

...FLASH FLOOD WATCH IS CANCELLED...

THE FLASH FLOOD WATCH FOR PORTIONS OF DELAWARE...NORTHEAST
MARYLAND...NEW JERSEY AND PENNSYLVANIA HAS BEEN CANCELLED. 

LIGHT TO OCCASIONALLY MODERATE SHOWERS WILL CONTINUE THIS EVENING
IN PARTS OF THE AREA. HOWEVER, THE THREAT OF ADDITIONAL HEAVY
RAINFALL AND FLASH FLOODING HAS ENDED.

$$
JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 10, 4:46 AM EDTSpecial Weather StatementPHIBurlington, Camden, Gloucester, Mercer, Middlesex, Monmouth and 1 more119 min
Sep 10, 6:35 AM EDTSpecial Marine WarningPHI55 min
Sep 10, 6:40 AM EDTSpecial Weather StatementPHIAtlantic65 min
Sep 10, 7:23 AM EDTSpecial Marine WarningPHI67 min
Sep 10, 12:02 PM EDTAreal Flood AdvisoryPHIBurlington, Camden, Gloucester4 hr
Sep 10, 3:29 PM EDTAreal Flood AdvisoryPHIHunterdon, Mercer, Somerset3 hr
Sep 10, 4:14 PM EDTAreal Flood AdvisoryPHIWarren3 hr
Sep 10, 2:15 PM EDTAreal Flood WarningPHIPhiladelphia3 hr
Sep 10, 3:22 PM EDTAreal Flood AdvisoryPHIBerks, Lehigh3 hr
Sep 10, 3:49 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Chester, Lehigh, Montgomery3 hr
Sep 10, 6:19 PM EDTFlash Flood WarningPHIChester, Montgomery116 min
Sep 10, 10:42 AM EDTSpecial Weather StatementPHISussex63 min
Sep 10, 12:14 PM EDTSpecial Weather StatementPHIKent61 min
Sep 10, 12:17 PM EDTAreal Flood AdvisoryPHIKent4 hr
Sep 10, 3:52 PM EDTSpecial Weather StatementPHIKent38 min
Sep 10, 4:40 PM EDTAreal Flood AdvisoryPHIKent2 hr
Sep 9, 11:03 PM EDTSpecial Weather StatementPHICaroline27 min
Sep 10, 3:34 PM EDTSpecial Weather StatementPHIQueen Anne's, Talbot56 min

Nearby

Flash Flood Watches in Pennsylvania, 2015Flash Flood Watches in New Jersey, 2015Flash Flood Watches in Maryland, 2015Every flash flood watch in 2015

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.