Alert archive / Maryland / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 160, NWS Philadelphia/Mount Holly

July 31, 2009Cecil County, Kent County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 31, 2009, 3:10 PM EDT for Cecil County, Kent County, Maryland. It was in force for 65 min. 1 report 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
Jul 31, 2009, 3:10 PM EDT (19:10 UTC)
Expired
Jul 31, 2009, 4:15 PM EDT
In force
65 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Cecil County, MD, Kent County, MD

The radar

The Dover AFB radar (KDOX), 74 km from the middle of the area, began a volume at 19:10 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

TimeReportWhereRemark
Jul 31, 4:00 PM EDTTSTM WND DMGChestertown, MDTREES AND WIRES REPORTED DOWN IN CHESTERTOWN AND ROCK HALL.

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.

IssuedProductOfficeLasted
Jul 31, 1:18 PM EDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 7.2 hours before the alert went out and 127 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 2009-07-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 276 joules per kilogram.LCLLFCEL10008507005003002001001 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 2009-07-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -25 square meters per square second.19395878Sfc1 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
276 J/kg
Mixed-layer CIN
-61 J/kg
Mixed-layer LCL
888 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
-25 m²/s²
0-3 km storm-relative helicity
18 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS51 KPHI 311910
SVRPHI
MDC015-029-312015-
/O.NEW.KPHI.SV.W.0160.090731T1910Z-090731T2015Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
310 PM EDT FRI JUL 31 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN CECIL COUNTY IN NORTHEAST MARYLAND...
  KENT COUNTY IN NORTHEAST MARYLAND...

* UNTIL 415 PM EDT

* AT 307 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH.  THIS STORM WAS LOCATED 13 MILES SOUTHWEST OF NEWTOWN...
  OR 15 MILES SOUTHEAST OF BALTIMORE...AND MOVING EAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  NEWTOWN AROUND 335 PM EDT...
  CHESTERTOWN AROUND 340 PM EDT...
  7 MILES SOUTH OF BETTERTON AROUND 345 PM EDT...
  MORGNEC AND KENNEDYVILLE AROUND 350 PM EDT...
  MASSEY AND 8 MILES SOUTH OF CECILTON AROUND 410 PM EDT...
  SASSAFRAS AROUND 415 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM SHOWS SIGNS OF ROTATION ON RADAR AND COULD PRODUCE A 
SMALL TORNADO.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT FRIDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

&&

LAT...LON 3934 7617 3934 7615 3938 7611 3938 7600
      3940 7605 3946 7600 3953 7579 3926 7578
      3925 7582 3927 7586 3925 7591 3925 7598
      3921 7604 3918 7627
TIME...MOT...LOC 1909Z 258DEG 24KT 3921 7635

$$

AMC
1 follow-up statement
000 
WWUS51 KPHI 311935
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
335 PM EDT FRI JUL 31 2009

MDC015-029-312015-
/O.CON.KPHI.SV.W.0160.000000T0000Z-090731T2015Z/
CECIL MD-KENT MD-
335 PM EDT FRI JUL 31 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM EDT
FOR NORTHEASTERN KENT AND SOUTHEASTERN CECIL COUNTIES...

AT 331 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR BETTERTON...OR 23
MILES SOUTHWEST OF MIDDLETOWN...MOVING EAST AT 30 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  KENNEDYVILLE BY 340 PM EDT...
  GALENA BY 355 PM EDT...
  CECILTON BY 400 PM EDT...
  SASSAFRAS AND 7 MILES SOUTH OF CAYOTS BY 405 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM CONTINUES TO SHOW SIGNS OF ROTATION ON RADAR AND COULD 
PRODUCE A FUNNEL CLOUD OR A SMALL TORNADO.

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...CONTINUOUS CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS.
REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE
STRUCK BY LIGHTNING.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT FRIDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

&&

LAT...LON 3927 7606 3933 7616 3938 7611 3938 7600
      3940 7605 3946 7600 3953 7579 3933 7578
TIME...MOT...LOC 1934Z 249DEG 27KT 3931 7608

$$

AMC

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 3:04 PM EDTFlash Flood WarningPHICecil3 hr
Jul 31, 3:40 PM EDTSevere Thunderstorm WarningPHICecil65 min
Jul 31, 3:54 PM EDTSevere Thunderstorm WarningPHICaroline, Kent, Queen Anne's53 min
Jul 31, 4:08 PM EDTFlash Flood WarningPHICecil3 hr

Nearby

Severe Thunderstorm Warnings in Maryland, 2009Every severe thunderstorm warning in 2009

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.