Alert archive / Pennsylvania / Flash Flood Warnings in 2019

Flash Flood Warning 35, NWS Philadelphia/Mount Holly

June 29, 2019Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 29, 2019, 3:45 PM EDT for Chester County, Pennsylvania. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jun 29, 2019, 3:45 PM EDT (19:45 UTC)
Expired: Jun 29, 2019, 6:54 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 111 km from the middle of the area, began a volume at 19:45 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, 7.8 hours before the alert went out and 185 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 927 J/kg
Mixed-layer CIN: -115 J/kg
Mixed-layer LCL: 1390 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: -10 m²/s²
0-3 km storm-relative helicity: 2 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

269 
WGUS51 KPHI 291945
FFWPHI
PAC029-292345-
/O.NEW.KPHI.FF.W.0035.190629T1945Z-190629T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
345 PM EDT Sat Jun 29 2019

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Chester County in southeastern Pennsylvania...

* Until 745 PM EDT.

* At 344 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to two inches of rain may 
  occur in less than an hour. Flash flooding is expected to begin 
  shortly in the areas of heaviest rain.

* Some locations that could experience flooding include...
  West Chester, Pottstown, Phoenixville, Coatesville, Westtown,
  Downingtown, Kennett Square, Oxford, Parkesburg, West Grove, Honey
  Brook, Elverson, Homeville, Glen Roy, Cochranville, Pughtown, Mount
  Vernon, Marshallton, Lionville-Marchwood and Valley Forge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 3976 7606 3987 7599 3995 7600 4004 7593
      4011 7594 4023 7571 4024 7560 4015 7553
      4016 7550 4014 7551 4013 7546 4009 7545
      4007 7536 3998 7544 3990 7558 3984 7559
      3980 7571 3972 7577 3972 7613

$$

CMS

1 follow-up statement

059 
WGUS71 KPHI 292254
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
654 PM EDT Sat Jun 29 2019

PAC029-292303-
/O.CAN.KPHI.FF.W.0035.000000T0000Z-190629T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
654 PM EDT Sat Jun 29 2019

...THE FLASH FLOOD WARNING FOR CHESTER COUNTY IS CANCELLED...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed any remaining road closures and 
watch for residual ponding on roadways.

LAT...LON 3976 7606 3987 7599 3995 7600 4004 7593
      4011 7594 4023 7571 4024 7560 4015 7553
      4016 7550 4014 7551 4013 7546 4009 7545
      4007 7536 3998 7544 3990 7558 3984 7559
      3980 7571 3972 7577 3972 7613

$$

Staarmann

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 29, 2:27 PM EDT	Severe Thunderstorm Warning	PHI	Berks	63 min
Jun 29, 2:46 PM EDT	Special Weather Statement	PHI	Chester	29 min
Jun 29, 3:06 PM EDT	Special Weather Statement	PHI	Chester	24 min
Jun 29, 3:09 PM EDT	Severe Thunderstorm Warning	PHI	Chester	51 min
Jun 29, 3:20 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery, Northampton	55 min
Jun 29, 3:24 PM EDT	Severe Thunderstorm Warning	PHI	Delaware	36 min
Jun 29, 3:27 PM EDT	Severe Thunderstorm Warning	PHI	Chester	53 min
Jun 29, 3:52 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	53 min
Jun 29, 3:56 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	49 min
Jun 29, 3:59 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	46 min
Jun 29, 4:00 PM EDT	Flash Flood Warning	PHI	Chester, Delaware	3 hr
Jun 29, 4:17 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh, Northampton	3 hr
Jun 29, 4:28 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Delaware, Montgomery, Philadelphia	47 min
Jun 29, 4:41 PM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	3 hr
Jun 29, 7:10 PM EDT	Special Weather Statement	PHI	Berks	35 min
Jun 29, 7:16 PM EDT	Special Weather Statement	PHI	Lebanon	29 min

Nearby

Flash Flood Warnings in Pennsylvania, 2019 Every flash flood warning in 2019

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.