Alert archive / Pennsylvania / Snow Squall Warnings in 2020

Snow Squall Warning 1, NWS Philadelphia/Mount Holly

January 8, 2020Chester County, Pennsylvania; New Castle County, Delaware; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this snow squall warning at Jan 8, 2020, 7:44 AM EST for Chester County, Pennsylvania; New Castle County, Delaware; Cecil County, Maryland. It was in force for 46 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 8, 2020, 7:44 AM EST (12:44 UTC)
Expired
Jan 8, 2020, 8:30 AM EST
In force
46 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties New Castle County, DE, Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 89 km from the middle of the area, began a volume at 12:46 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, 0.7 hours before the alert went out and 159 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 2020-01-08Temperature 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 12:00Z on 2020-01-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 348 square meters per square second.1939587897117Sfc1 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
1404 m above ground
0-6 km bulk shear
103 kt
0-1 km storm-relative helicity
348 m²/s²
0-3 km storm-relative helicity
424 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

391 
WWUS51 KPHI 081245
SQWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Snow Squall Warning
National Weather Service Mount Holly NJ
744 AM EST Wed Jan 8 2020

DEC003-MDC015-PAC029-081330-
/O.NEW.KPHI.SQ.W.0001.200108T1244Z-200108T1330Z/
New Castle DE-Cecil MD-Chester PA-
744 AM EST Wed Jan 8 2020

The National Weather Service in Mount Holly NJ has issued a

* Snow Squall Warning for...
  New Castle County in northern Delaware...
  Cecil County in northeastern Maryland...
  Southwestern Chester County in southeastern Pennsylvania...

* Until 830 AM EST.

* At 744 AM EST, a dangerous snow squall was located near Bel Air
  North, or 11 miles northwest of Aberdeen, moving east at 65 mph.

  HAZARD...Extremely poor visibility in heavy snow.

  SOURCE...Radar indicated.

  IMPACT...Dangerous life-threatening travel.

* This includes the following highways...
   Interstate 95 in Maryland between mile markers 91 and 109.
   Interstate 95 in Delaware between mile markers 0 and 16.

Locations impacted include...
Wilmington, Newark, Middletown, Elkton, Calvert, Elsmere, Kennett
Square, New Castle, Oxford, North East, West Grove, Rising Sun,
Delaware City, Charlestown, Newport, Cecilton, Glen Roy, Blake,
Stanton and Glasgow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3972 7623 3973 7610 3989 7598 3990 7558
      3986 7560 3984 7555 3966 7553 3962 7556
      3960 7554 3960 7552 3946 7554 3945 7550
      3934 7548 3936 7551 3934 7556 3938 7578
      3938 7592 3941 7601 3952 7598 3955 7608
TIME...MOT...LOC 1244Z 281DEG 59KT 3963 7633 

$$

JEO
2 follow-up statements
048 
WWUS51 KPHI 081311
SQWPHI

Snow Squall Warning
National Weather Service Mount Holly NJ
810 AM EST Wed Jan 8 2020

DEC003-MDC015-PAC029-081330-
/O.CON.KPHI.SQ.W.0001.000000T0000Z-200108T1330Z/
New Castle DE-Cecil MD-Chester PA-
810 AM EST Wed Jan 8 2020

...A SNOW SQUALL WARNING REMAINS IN EFFECT UNTIL 830 AM EST FOR NEW
CASTLE...CECIL AND SOUTHWESTERN CHESTER COUNTIES...

At 810 AM EST, a dangerous snow squall was located over Brantwood, 
or near Elkton, moving east at 70 mph. This squall has a history of 
producing 1 to 2 inches of snow in less than one hour. Roads will 
rapidly become snow covered.

HAZARD...Extremely poor visibility in heavy snow.

SOURCE...Radar indicated.

IMPACT...Dangerous life-threatening travel.

This includes the following highways...
 Interstate 95 in Maryland between mile markers 91 and 109.
 Interstate 95 in Delaware between mile markers 0 and 16.

Locations impacted include...
Wilmington, Newark, Middletown, Elkton, Calvert, Elsmere, Kennett
Square, New Castle, Oxford, North East, West Grove, Rising Sun,
Delaware City, Charlestown, Newport, Cecilton, Glen Roy, Blake,
Stanton and Glasgow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3972 7623 3973 7610 3989 7598 3990 7558
      3986 7560 3984 7555 3966 7553 3962 7556
      3960 7554 3960 7552 3946 7554 3945 7550
      3934 7548 3936 7551 3934 7556 3938 7578
      3938 7592 3941 7601 3952 7598 3955 7608
TIME...MOT...LOC 1310Z 281DEG 59KT 3955 7579 

$$

JEO
250 
WWUS51 KPHI 081326
SQWPHI

Snow Squall Warning
National Weather Service Mount Holly NJ
825 AM EST Wed Jan 8 2020

DEC003-MDC015-PAC029-081335-
/O.EXP.KPHI.SQ.W.0001.000000T0000Z-200108T1330Z/
New Castle DE-Cecil MD-Chester PA-
825 AM EST Wed Jan 8 2020

...THE SNOW SQUALL WARNING FOR NEW CASTLE...CECIL AND SOUTHWESTERN
CHESTER COUNTIES WILL EXPIRE AT 830 AM EST...

The snow squall which prompted the warning has moved out of the 
warned area. Therefore, the snow squall warning will be allowed to 
expire. Roads will remain snow covered.

LAT...LON 3972 7623 3973 7610 3989 7598 3990 7558
      3986 7560 3984 7555 3966 7553 3962 7556
      3960 7554 3960 7552 3946 7554 3945 7550
      3934 7548 3936 7551 3934 7556 3938 7578
      3938 7592 3941 7601 3952 7598 3955 7608
TIME...MOT...LOC 1325Z 281DEG 59KT 3952 7557 

$$

JEO

The office that day

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

IssuedProductOfficeCountiesLasted
Jan 8, 7:49 AM ESTSnow Squall WarningPHICarbon, Monroe, Northampton41 min
Jan 8, 8:28 AM ESTSnow Squall WarningPHIBerks, Bucks, Chester, Delaware, Montgomery47 min
Jan 8, 8:28 AM ESTSnow Squall WarningPHIChester, Delaware, Montgomery, Philadelphia47 min
Jan 8, 8:30 AM ESTSnow Squall WarningPHIMonroe45 min
Jan 8, 11:25 AM ESTSnow Squall WarningPHIBerks35 min
Jan 8, 12:07 PM ESTSpecial Weather StatementPHIMontgomery23 min
Jan 8, 12:38 PM ESTSpecial Weather StatementPHIMontgomery, Philadelphia37 min
Jan 8, 12:49 PM ESTSnow Squall WarningPHIChester, Delaware, Montgomery, Philadelphia26 min
Jan 8, 1:48 PM ESTSnow Squall WarningPHICarbon, Monroe42 min
Jan 8, 2:05 PM ESTSpecial Weather StatementPHIMontgomery25 min
Jan 8, 2:32 PM ESTSpecial Weather StatementPHICarbon, Northampton28 min
Jan 8, 2:33 PM ESTSpecial Weather StatementPHIPhiladelphia27 min
Jan 8, 2:46 PM ESTSpecial Weather StatementPHIBerks44 min
Jan 8, 3:05 PM ESTSpecial Weather StatementPHINorthampton40 min
Jan 8, 9:19 AM ESTSpecial Weather StatementPHINew Castle26 min

Nearby

Snow Squall Warnings in Pennsylvania, 2020Snow Squall Warnings in Delaware, 2020Snow Squall Warnings in Maryland, 2020Every snow squall warning in 2020

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.