Alert archive / Maryland / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 8, NWS Philadelphia/Mount Holly

February 25, 20174 counties in Maryland; Chester County, Delaware County, Pennsylvania; Kent County, New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Feb 25, 2017, 4:04 PM EST for 4 counties in Maryland; Chester County, Delaware County, Pennsylvania; Kent County, New Castle County, Delaware. It was in force for 41 min. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Feb 25, 2017, 4:04 PM EST (21:04 UTC)
Expired: Feb 25, 2017, 4:45 PM EST
In force: 41 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Kent County, DE, New Castle County, DE, Caroline County, MD, Cecil County, MD, Kent County, MD, Queen Anne's County, MD, Chester County, PA, Delaware County, PA

The radar

The Dover AFB radar (KDOX), 76 km from the middle of the area, began a volume at 21:05 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.

What was reported inside it

Time	Report	Where	Remark
Feb 25, 4:10 PM EST	TSTM WND DMG	Charlestown, MD	TREE BLOWN DOWN
Feb 25, 4:25 PM EST	TSTM WND DMG	Still Pond, MD	TREES DOWN
Feb 25, 4:48 PM EST	TSTM WND GST 60	Concord Twp, PA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Feb 25, 1:30 PM EST	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.1 hours before the alert went out and 125 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: 235 J/kg
Mixed-layer CIN: -194 J/kg
Mixed-layer LCL: 676 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 164 m²/s²
0-3 km storm-relative helicity: 143 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

846 
WUUS51 KPHI 252104
SVRPHI
DEC001-003-MDC011-015-029-035-PAC029-045-252145-
/O.NEW.KPHI.SV.W.0008.170225T2104Z-170225T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
404 PM EST SAT FEB 25 2017

The National Weather Service in Mount Holly NJ  has issued a

* Severe Thunderstorm Warning for...
  New Castle County in northern Delaware...
  Northwestern Kent County in central Delaware...
  Central Queen Anne's County in northeastern Maryland...
  North central Caroline County in eastern Maryland...
  Kent County in northeastern Maryland...
  Cecil County in northeastern Maryland...
  Southeastern Chester County in southeastern Pennsylvania...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 445 PM EST

* At 403 PM EST, severe thunderstorms were located along a line
  extending from Calvert to near Stevensville, moving east at 40 mph.

  HAZARD...60 mph wind gusts and quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees. 

* Locations impacted include...
  Wilmington, Newark, Middletown, Elkton, Havre De Grace, Calvert,
  Pennsville, Westtown, Elsmere, Kennett Square, New Castle,
  Chestertown, Oxford, Centreville, North East, West Grove, Rising
  Sun, Delaware City, Rock Hall and Charlestown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People 
outside should move immediately to shelter inside a strong building. 
Stay away from windows.

In addition to large hail and damaging winds...frequent cloud to
ground lightning is occurring with this storm. Move indoors
immediately. Remember...if you can hear thunder...you are close
enough to be struck by lightning.

&&

LAT...LON 3904 7631 3901 7628 3905 7623 3917 7628
      3923 7624 3929 7617 3932 7618 3942 7600
      3952 7598 3956 7609 3969 7621 3998 7547
      3965 7553 3963 7556 3960 7555 3909 7576
      3902 7624 3898 7633
TIME...MOT...LOC 2103Z 253DEG 35KT 3971 7601 3902 7635 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

Robertson

The office that day

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

Issued	Product	Office	Counties	Lasted
Feb 25, 3:05 PM EST	Special Weather Statement	PHI	Cecil, Kent, Queen Anne's, Talbot	55 min
Feb 25, 3:18 PM EST	Severe Thunderstorm Warning	PHI	Caroline, Queen Anne's, Talbot	57 min
Feb 25, 3:26 PM EST	Severe Thunderstorm Warning	PHI	Cecil	64 min
Feb 25, 4:11 PM EST	Severe Thunderstorm Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	49 min
Feb 25, 4:50 PM EST	Severe Thunderstorm Warning	PHI	Caroline, Talbot	55 min
Feb 25, 5:07 PM EST	Special Weather Statement	PHI	Kent	38 min
Feb 25, 2:22 PM EST	Special Weather Statement	PHI	Lebanon	53 min
Feb 25, 2:47 PM EST	Severe Thunderstorm Warning	PHI	Berks	43 min
Feb 25, 2:55 PM EST	Special Weather Statement	PHI	Carbon	50 min
Feb 25, 3:02 PM EST	Special Weather Statement	PHI	Berks	58 min
Feb 25, 3:19 PM EST	Severe Thunderstorm Warning	PHI	Berks, Carbon, Lehigh, Northampton	41 min
Feb 25, 3:57 PM EST	Special Weather Statement	PHI	Lehigh, Montgomery	48 min
Feb 25, 4:05 PM EST	Severe Thunderstorm Warning	PHI	Carbon, Lehigh, Monroe	40 min
Feb 25, 4:17 PM EST	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Monroe and 3 more	43 min
Feb 25, 4:34 PM EST	Special Weather Statement	PHI	Monroe	41 min
Feb 25, 4:40 PM EST	Severe Thunderstorm Warning	PHI	Delaware, Montgomery, Philadelphia	50 min
Feb 25, 4:54 PM EST	Severe Thunderstorm Warning	PHI	Bucks, Monroe	51 min
Feb 25, 5:01 PM EST	Special Weather Statement	PHI	Bucks	44 min
Feb 25, 5:17 PM EST	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	43 min
Feb 25, 6:10 PM EST	Special Weather Statement	PHI	Delaware	35 min
Feb 25, 5:42 PM EST	Special Weather Statement	PHI	New Castle	33 min
Feb 25, 5:45 PM EST	Special Weather Statement	PHI	Sussex	30 min
Feb 25, 5:46 PM EST	Special Weather Statement	PHI	Sussex	29 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2017 Severe Thunderstorm Warnings in Pennsylvania, 2017 Severe Thunderstorm Warnings in Delaware, 2017 Every severe thunderstorm warning in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.