Alert archive / Pennsylvania / Snow Squall Warnings in 2024

Snow Squall Warning 10, NWS Philadelphia/Mount Holly

January 14, 2024Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this snow squall warning at Jan 14, 2024, 12:28 PM EST for Chester County, Pennsylvania. It was in force for 20 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jan 14, 2024, 12:28 PM EST (17:28 UTC)
Expired
Jan 14, 2024, 12:48 PM EST
In force
20 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 103 km from the middle of the area, began a volume at 17:27 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, 5.5 hours before the alert went out and 193 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 2024-01-14Temperature 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°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2024-01-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 190 square meters per square second.1939587897117136156175Sfc1 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
1565 m above ground
0-6 km bulk shear
92 kt
0-1 km storm-relative helicity
190 m²/s²
0-3 km storm-relative helicity
149 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

130 
WWUS51 KPHI 141728
SQWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Snow Squall Warning
National Weather Service Mount Holly NJ
1228 PM EST Sun Jan 14 2024

PAC029-141800-
/O.NEW.KPHI.SQ.W.0010.240114T1728Z-240114T1800Z/
Chester PA-
1228 PM EST Sun Jan 14 2024

The National Weather Service in Mount Holly NJ has issued a

* Snow Squall Warning for...
  Central Chester County in southeastern Pennsylvania...

* Until 100 PM EST.

* At 1228 PM EST, a dangerous snow squall was located along a line
  extending from near King Of Prussia to near Cochranville, moving
  southeast at 30 mph.

  HAZARD...Intense bursts of heavy snow and gusty winds leading to 
           blowing snow and rapidly falling visibility. Wind gusts 
           greater than 35 mph.

  SOURCE...Radar and webcams.

  IMPACT...Travel will become difficult and potentially dangerous 
           within minutes.

This includes Pennsylvania Turnpike between mile markers 320 and 325.
 
Locations impacted include...
West Chester, Downingtown, Kennett Square, Paoli, Marshallton, Valley
Forge, King Of Prussia, West Goshen, Malvern, South Coatesville,
Modena, Exton, Chesterbrook, Devon-Berwyn, and Thorndale.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow Down! Rapid changes in visibility and road conditions are
expected with this dangerous snow squall. Be alert for sudden
whiteout conditions.

Consider avoiding or delaying travel until the snow squall passes
your location. If you must travel, use extra caution and allow extra
time. Rapid changes in visibility and slick road conditions may lead
to accidents.

&&

LAT...LON 3992 7594 4010 7546 4009 7542 4008 7540
      4007 7541 3984 7572
TIME...MOT...LOC 1728Z 294DEG 24KT 4007 7540 3991 7584 

SNOW SQUALL...OBSERVED

$$

MJL
1 follow-up statement
811 
WWUS51 KPHI 141748
SQWPHI

Snow Squall Warning
National Weather Service Mount Holly NJ
1248 PM EST Sun Jan 14 2024

PAC029-141758-
/O.CAN.KPHI.SQ.W.0010.000000T0000Z-240114T1800Z/
Chester PA-
1248 PM EST Sun Jan 14 2024

...THE SNOW SQUALL WARNING FOR CENTRAL CHESTER COUNTY IS CANCELLED...

The snow squall that prompted the warning has exited the area.
Therefore, the snow squall warning has been cancelled. Snow showers 
may still restrict visibilities down to 1 mile at times. Heed any 
additional Snow Squall Warnings if they are issued.

LAT...LON 3992 7594 4010 7546 4009 7542 4008 7540
      4007 7541 3984 7572
TIME...MOT...LOC 1744Z 294DEG 24KT 4002 7527 3986 7571 

$$

MJL

The office that day

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

IssuedProductOfficeCountiesLasted
Jan 14, 2:48 AM ESTWind AdvisoryPHIBerks, Bucks, Carbon, Chester, Delaware, Lehigh and 4 more15 hr
Jan 14, 10:28 AM ESTSnow Squall Warning Significant damage threatPHICarbon, Monroe62 min
Jan 14, 10:43 AM ESTSnow Squall WarningPHIBerks47 min
Jan 14, 11:07 AM ESTSnow Squall WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery, Northampton38 min
Jan 14, 11:30 AM ESTSnow Squall Warning Significant damage threatPHICarbon, Monroe60 min
Jan 14, 11:42 AM ESTSnow Squall Warning Significant damage threatPHIBerks, Chester, Montgomery48 min
Jan 14, 11:44 AM ESTSnow Squall WarningPHIBucks61 min
Jan 14, 11:57 AM ESTSnow Squall WarningPHIChester48 min
Jan 14, 12:17 PM ESTSnow Squall WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia28 min
Jan 14, 12:24 PM ESTSnow Squall Warning Significant damage threatPHIMonroe28 min

Nearby

Snow Squall Warnings in Pennsylvania, 2024Every snow squall warning in 2024

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.