Alert archive / Pennsylvania / Flash Flood Watches in 2017

Flash Flood Watch 2, NWS Philadelphia/Mount Holly

July 6, 20174 states

NWS Philadelphia/Mount Holly issued this flash flood watch at Jul 6, 2017, 4:16 PM EDT for 4 states. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued
Jul 6, 2017, 4:16 PM EDT (20:16 UTC)
Expired
Jul 6, 2017, 7:16 PM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Flood severity
None

Counties New Castle County, DE, Cecil County, MD, Kent County, MD, Camden County, NJ, Gloucester County, NJ, Salem County, NJ, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 20:19 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, 8.3 hours before the alert went out and 188 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 2017-07-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 227 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 2017-07-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 33 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
227 J/kg
Mixed-layer CIN
-1 J/kg
Mixed-layer LCL
468 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
33 m²/s²
0-3 km storm-relative helicity
37 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

592 
WGUS61 KPHI 062016
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Mount Holly NJ
416 PM EDT Thu Jul 6 2017


DEZ001-MDZ008-012-NJZ016>018-PAZ070-071-102-104-070900-
/O.NEW.KPHI.FF.A.0002.170706T2016Z-170707T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Cecil-Kent MD-Salem-Gloucester-Camden-Delaware-
Philadelphia-Eastern Chester-Eastern Montgomery-
Including the cities of Wilmington, Elkton, Chestertown, 
Pennsville, Glassboro, Camden, Cherry Hill, Media, Philadelphia, 
West Chester, Kennett Square, Norristown, and Lansdale
416 PM EDT Thu Jul 6 2017

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...

The National Weather Service in Mount Holly has issued a

* Flash Flood Watch for portions of northern Delaware, northeast 
  Maryland, southern New Jersey, and southeast Pennsylvania, 
  including the following areas, in northern Delaware, New 
  Castle. In northeast Maryland, Cecil and Kent MD. In southern 
  New Jersey, Camden, Gloucester, and Salem. In southeast 
  Pennsylvania, Delaware, Eastern Chester, Eastern Montgomery, 
  and Philadelphia. 

* Through late tonight

* Small clusters of excessive rain producing showers will cause
  flooding in a few spots. The urban areas of Northern Delaware
  appear vulnerable to flooding this evening.  

* Travel will be impacted with poor drainage flooding this evening
  with storm totals by midnight near 1 inch, but isolated 5 inch 
  amounts possible. 


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.

You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued. 

&&

$$

Drag
1 follow-up statement
856 
WGUS61 KPHI 062316
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
716 PM EDT Thu Jul 6 2017

DEZ001-MDZ008-012-NJZ016>018-PAZ070-071-102-104-070030-
/O.CAN.KPHI.FF.A.0002.000000T0000Z-170707T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Cecil-Kent MD-Salem-Gloucester-Camden-Delaware-
Philadelphia-Eastern Chester-Eastern Montgomery-
Including the cities of Wilmington, Elkton, Chestertown, 
Pennsville, Glassboro, Camden, Cherry Hill, Media, Philadelphia, 
West Chester, Kennett Square, Norristown, and Lansdale
716 PM EDT Thu Jul 6 2017

...FLASH FLOOD WATCH IS CANCELLED...

The threat of heavy rain has decreased in extreme southeastern 
Pennsylvania, southwestern New Jersey, northern Delaware and 
northeastern Maryland. As a result, the Flash Flood Watch has been
cancelled.

$$

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 6, 3:35 PM EDTFlash Flood WarningPHICecil4 hr
Jul 6, 4:04 PM EDTAreal Flood AdvisoryPHICecil4 hr
Jul 6, 4:08 PM EDTSpecial Weather StatementPHIKent67 min
Jul 6, 4:17 PM EDTAreal Flood AdvisoryPHIKent3 hr
Jul 6, 5:39 PM EDTSpecial Weather StatementPHIKent66 min
Jul 6, 6:15 PM EDTAreal Flood AdvisoryPHIKent, Queen Anne's3 hr
Jul 6, 7:36 PM EDTAreal Flood WarningPHICecil, Kent10 hr
Jul 6, 2:41 PM EDTSpecial Weather StatementPHINew Castle64 min
Jul 6, 3:01 PM EDTAreal Flood AdvisoryPHINew Castle119 min

Nearby

Flash Flood Watches in Pennsylvania, 2017Flash Flood Watches in New Jersey, 2017Flash Flood Watches in Maryland, 2017Every flash flood watch in 2017

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.