Alert archive / Pennsylvania / Areal Flood Warnings in 2021

Areal Flood Warning 1, NWS Philadelphia/Mount Holly

February 28, 2021Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Feb 28, 2021, 7:38 PM EST 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
Feb 28, 2021, 7:38 PM EST (00:38 UTC)
Expired
Feb 28, 2021, 11:01 PM EST
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), 108 km from the middle of the area, began a volume at 00:38 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, 0.6 hours before the alert went out and 186 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 2021-03-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 00:00Z on 2021-03-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 309 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
547 m above ground
0-6 km bulk shear
66 kt
0-1 km storm-relative helicity
309 m²/s²
0-3 km storm-relative helicity
419 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

994 
WGUS41 KPHI 010038
FLWPHI

BULLETIN - EAS ACTIVATION REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
738 PM EST Sun Feb 28 2021

PAC029-010445-
/O.NEW.KPHI.FA.W.0001.210301T0038Z-210301T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
738 PM EST Sun Feb 28 2021

The National Weather Service in Mount Holly has issued a

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

* Until 1145 PM EST.

* At 738 PM EST, Doppler radar indicated heavy rain. Flooding is 
  ongoing or expected to begin shortly in the warned area. Between 1 
  and 1.5 inches of rain have fallen.

Some locations that may experience flooding include...
  Marshallton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Warning means that flooding is imminent or occurring. All 
interested parties should take necessary precautions immediately.

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

&&

LAT...LON 3997 7570 4000 7568 3993 7562 3992 7566

$$

Davis
1 follow-up statement
262 
WGUS81 KPHI 010401 RRA
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
1101 PM EST Sun Feb 28 2021

PAC029-010411-
/O.CAN.KPHI.FA.W.0001.000000T0000Z-210301T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
1101 PM EST Sun Feb 28 2021

...FLOOD WARNING IS CANCELLED FOR CENTRAL CHESTER COUNTY...

Flood waters have receded. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3997 7570 4000 7568 3993 7562 3992 7566

$$

Deal

The office that day

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

IssuedProductOfficeCountiesLasted
Feb 28, 7:43 PM ESTRiver Flood WarningPHIChester3 hr

Nearby

Areal Flood Warnings in Pennsylvania, 2021Every areal flood warning 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.