Tornado Watch 486

Issued

Jun 20, 2009, 3:05 PM EDT (19:05 UTC)

Expired

Jun 20, 2009, 7:43 PM EDT

In force

5 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

60 kt

The Dover AFB radar (KDOX), 97 km from the middle of the area, began a volume at 19:06 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.

Two or more tornadoes

30%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

20%

One or more gusts of 65 knots or more

10%

Ten or more severe hail reports

30%

One or more hailstones of 2 inches or more

10%

Six or more combined severe hail and wind reports

50%

• Mesoscale Discussion 1254Jun 20, 1:55 PM EDT

561 
WWUS20 KWNS 201906
SEL6  
SPC WW 201906
DEZ000-MDZ000-VAZ000-CWZ000-210000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 486
NWS STORM PREDICTION CENTER NORMAN OK
305 PM EDT SAT JUN 20 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       DELAWARE
       EASTERN AND SOUTHERN MARYLAND
       SOUTHEAST VIRGINIA
       COASTAL WATERS

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 305 PM UNTIL
800 PM EDT.

TORNADOES...HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE
MILES EITHER SIDE OF A LINE FROM 60 MILES SOUTH OF PATUXENT RIVER
MARYLAND TO 40 MILES NORTH NORTHWEST OF DOVER DELAWARE.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU6).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...WIDELY SCATTERED THUNDERSTORMS ARE DEVELOPING FROM
EXTREME SERN PA SWD INTO EAST CENTRAL VA IN ASSOCIATION WITH STRONG
DYNAMIC FORCING FOR LARGE SCALE ASCENT ALONG A SHORT WAVE
TROUGH/VORTICITY MAX MOVING EWD ACROSS THE MID ATLANTIC REGION.  THE
AIR MASS HAS WARMED SUBSTANTIALLY OVER THE AREA TO THE IMMEDIATE
WEST OF A WARM FRONT AND IN THE WAKE OF EARLIER CONVECTION...WITH
TEMPERATURES IN THE 80S AND DEW POINTS REMAINING IN THE LOW 70S. 
WIND PROFILES SUBSTANTIALLY WITH HEIGHT AND 40-50 KT WNWLY FLOW
ABOVE 2-3 KM IS CONTRIBUTING TO STRONG DEEP LAYER SHEAR AS WELL AS
150-300 MS/S2 LOW-LEVEL HELICITY.  THE ENVIRONMENT APPEARS FAVORABLE
FOR SUPERCELL STORMS TO DEVELOP WITH THREAT FOR ISOLATED TORNADOES
AS WELL AS LARGE HAIL AND DAMAGING WIND GUSTS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 28025.


...WEISS

Tornado Watches in Maryland, 2009Tornado Watches in Virginia, 2009Tornado Watches in Delaware, 2009Every tornado watch in 2009

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.