Alert archive / Pennsylvania / Flash Flood Watches in 2021
Flash Flood Watch 10, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood watch at Sep 7, 2021, 2:33 PM EDT for 7 counties in New Jersey; 10 counties in Pennsylvania; New Castle County, Delaware. It took effect at Sep 8, 2021, 4:00 PM EDT. It was in force for 12 hr.
The area
The counties it named.
The facts
- Issued
- Sep 7, 2021, 2:33 PM EDT (18:33 UTC)
- In effect from
- Sep 8, 2021, 4:00 PM EDT
- Expired
- Sep 9, 2021, 3:55 AM EDT
- In force
- 12 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Flood severity
- None
Counties New Castle County, DE, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Delaware County, PA, Lehigh County, PA, Monroe 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 18:33 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
Brookhaven, NY (KOKX), launched 12:00Z, 6.6 hours before the alert went out and 200 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1434 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 31 m²/s²
- 0-3 km storm-relative helicity
- 92 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
381 WGUS61 KPHI 071833 FFAPHI URGENT - IMMEDIATE BROADCAST REQUESTED Flood Watch National Weather Service Mount Holly NJ 233 PM EDT Tue Sep 7 2021 NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-080800- /O.NEW.KPHI.FF.A.0010.210908T2000Z-210909T0600Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-Carbon- Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks- Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West Chester, Morrisville, New Brunswick, Trenton, Newton, Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and Somerville 233 PM EDT Tue Sep 7 2021 ...FLASH FLOOD WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH LATE WEDNESDAY NIGHT... The National Weather Service in Mount Holly has issued a * Flash Flood Watch for portions of New Jersey...and Pennsylvania... including the following areas...in New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, Sussex, and Warren. In Pennsylvania... Berks, Carbon, Delaware, Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, Philadelphia, Upper Bucks, Western Chester, and Western Montgomery. * From Wednesday afternoon through late Wednesday night. * Thunderstorms with heavy rain are forecast to move through the region Wednesday evening. Given the very saturated soils from recent heavy rain events, additional brief heavy rainfall of one to two inches may quickly lead to flooding of flood prone and other low-lying areas due to rapid runoff. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$ Staarmann
5 follow-up statements
316 WGUS61 KPHI 080014 FFAPHI Flood Watch National Weather Service Mount Holly NJ 814 PM EDT Tue Sep 7 2021 NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-081215- /O.CON.KPHI.FF.A.0010.210908T2000Z-210909T0600Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-Carbon- Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks- Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West Chester, Morrisville, New Brunswick, Trenton, Newton, Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and Somerville 814 PM EDT Tue Sep 7 2021 ...FLASH FLOOD WATCH REMAINS IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH LATE WEDNESDAY NIGHT... The Flash Flood Watch continues for * Portions of New Jersey...and Pennsylvania...including the following areas...in New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, Sussex, and Warren. In Pennsylvania...Berks, Carbon, Delaware, Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, Philadelphia, Upper Bucks, Western Chester, and Western Montgomery. * From Wednesday afternoon through late Wednesday night. * Thunderstorms with heavy rain are forecast to move through the region Wednesday evening. Given the very saturated soils from recent heavy rain events, additional brief heavy rainfall of one to two inches may quickly lead to flooding of flood prone and other low-lying areas due to rapid runoff. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$
929 WGUS61 KPHI 080749 FFAPHI Flood Watch National Weather Service Mount Holly NJ 349 AM EDT Wed Sep 8 2021 NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-082000- /O.CON.KPHI.FF.A.0010.210908T2000Z-210909T0600Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-Carbon- Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks- Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West Chester, Morrisville, New Brunswick, Trenton, Newton, Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and Somerville 349 AM EDT Wed Sep 8 2021 ...FLASH FLOOD WATCH REMAINS IN EFFECT FROM THIS AFTERNOON THROUGH LATE TONIGHT... The Flash Flood Watch continues for * Portions of New Jersey...and Pennsylvania...including the following areas...in New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, Sussex, and Warren. In Pennsylvania...Berks, Carbon, Delaware, Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, Philadelphia, Upper Bucks, Western Chester, and Western Montgomery. * From this afternoon through late tonight. * Thunderstorms with heavy rain are forecast to move through the region this evening. Given the very saturated soils from recent heavy rain events, additional brief heavy rainfall of one to two inches may quickly lead to flooding of flood prone and other low-lying areas due to rapid runoff. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$ Fitzsimmons
878 WGUS61 KPHI 081858 FFAPHI Flood Watch National Weather Service Mount Holly NJ 258 PM EDT Wed Sep 8 2021 NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-090600- /O.CON.KPHI.FF.A.0010.210908T2000Z-210909T0600Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-Carbon- Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks- Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West Chester, Morrisville, New Brunswick, Trenton, Newton, Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and Somerville 258 PM EDT Wed Sep 8 2021 ...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 2 AM EDT THURSDAY... The Flash Flood Watch continues for * Portions of New Jersey...and Pennsylvania...including the following areas...in New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, Sussex, and Warren. In Pennsylvania...Berks, Carbon, Delaware, Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, Philadelphia, Upper Bucks, Western Chester, and Western Montgomery. * Until 2 AM EDT Thursday. * Thunderstorms with heavy rain are forecast to move through the region this evening. Given the very saturated soils from recent heavy rain events, additional brief heavy rainfall of one to two inches may quickly lead to flooding of flood prone and other low-lying areas due to rapid runoff. $$ Davis
483 WGUS61 KPHI 082204 FFAPHI URGENT - IMMEDIATE BROADCAST REQUESTED Flood Watch National Weather Service Mount Holly NJ 604 PM EDT Wed Sep 8 2021 DEZ001-090800- /O.EXB.KPHI.FF.A.0010.000000T0000Z-210909T0800Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ New Castle- Including the cities of Wilmington 604 PM EDT Wed Sep 8 2021 ...FLASH FLOOD WATCH IN EFFECT UNTIL 4 AM EDT THURSDAY... The National Weather Service in Mount Holly has expanded the * Flash Flood Watch to include a portion of northern Delaware... including the following area...New Castle. * Until 4 AM EDT Thursday. * Thunderstorms with heavy rain are forecast to move through the region this evening into the overnight period. Heavy rainfall of one to two inches may quickly lead to flooding of flood prone and other low-lying areas due to rapid runoff. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$ NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-090800- /O.EXT.KPHI.FF.A.0010.000000T0000Z-210909T0800Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-Carbon- Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks- Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West Chester, Morrisville, New Brunswick, Trenton, Newton, Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and Somerville 604 PM EDT Wed Sep 8 2021 ...FLASH FLOOD WATCH NOW IN EFFECT UNTIL 4 AM EDT THURSDAY... The Flash Flood Watch is now in effect for * Portions of New Jersey...and Pennsylvania...including the following areas...in New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, Sussex, and Warren. In Pennsylvania...Berks, Carbon, Delaware, Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, Philadelphia, Upper Bucks, Western Chester, and Western Montgomery. * Until 4 AM EDT Thursday. * Thunderstorms with heavy rain are forecast to move through the region this evening. Given the very saturated soils from recent heavy rain events, additional brief heavy rainfall of one to two inches may quickly lead to flooding of flood prone and other low-lying areas due to rapid runoff. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$ NC
921 WGUS61 KPHI 090755 FFAPHI Flood Watch National Weather Service Mount Holly NJ 355 AM EDT Thu Sep 9 2021 DEZ001-NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106- 090900- /O.CAN.KPHI.FF.A.0010.000000T0000Z-210909T0800Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer- Carbon-Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks- Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West Chester, Morrisville, Wilmington, New Brunswick, Trenton, Newton, Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and Somerville 355 AM EDT Thu Sep 9 2021 ...FLASH FLOOD WATCH IS CANCELLED... The Flash Flood Watch for portions of northern Delaware...New Jersey...and Pennsylvania...including the following areas...in northern Delaware...New Castle. In New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, Sussex, and Warren. In Pennsylvania... Berks, Carbon, Delaware, Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, Philadelphia, Upper Bucks, Western Chester, and Western Montgomery has been cancelled. The threat for heavy rain is decreasing. However, portions of the watch area remain under a flash flood warning. $$ SFJ
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 7, 2:42 AM EDT | Small Craft Advisory | PHI | 4 days |
Nearby
Flash Flood Watches in Pennsylvania, 2021Flash Flood Watches in New Jersey, 2021Flash Flood Watches in Delaware, 2021Every flash flood watch in 2021
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.