URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 486 
STORM PREDICTION CENTER NORMAN OK 
1022 AM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

WESTERN MASSACHUSETTS                      
WESTERN MAINE                              
NEW HAMPSHIRE                      
EASTERN NEW YORK                           
VERMONT                            

EFFECTIVE THIS SUNDAY MORNING AND AFTERNOON FROM 1030 AM UNTIL 400 PM
EDT. 

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 85 STATUTE MILES EAST
AND WEST OF A LINE FROM 55 MILES SOUTH SOUTHWEST OF ALBANY NEW YORK TO
25 MILES NORTH NORTHEAST OF BERLIN NEW HAMPSHIRE. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

DISCUSSION...PRE-FRONTAL THUNDERSTORMS ARE EXPECTED TO INTENSIFY AND
ACCELERATE EWD THROUGH THIS AFTERNOON IN ADVANCE OF THE AMPLIFYING MID
LEVEL TROUGH OVER THE ERN GREAT LAKES. STRENGTHENING WIND FIELDS...IN
COMBINATION WITH DAYTIME HEATING AND THE DEVELOPMENT OF MODERATE
INSTABILITY...WILL SUPPORT A THREAT OF WIDESPREAD DAMAGING WINDS AS THE
CONVECTION BECOMES MORE ORGANIZED BY EARLY AFTERNOON. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2
INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70 KNOTS.  A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 27045. 

...THOMPSON



URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 487 
STORM PREDICTION CENTER NORMAN OK 
1128 AM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

EASTERN OHIO                               
WESTERN PENNSYLVANIA                       
EXTREME NORTHWEST WEST VIRGINIA                      

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM NOON EDT UNTIL 600 PM
EDT. 

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 75 STATUTE MILES NORTH
AND SOUTH OF A LINE FROM 15 MILES WEST NORTHWEST OF ZANESVILLE OHIO TO
20 MILES SOUTH SOUTHEAST OF DUBOIS PENNSYLVANIA. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

OTHER WATCH INFORMATION...  CONTINUE...WW 485...WW 486... 

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE/
INTENSITY ALONG PRE-FRONTAL TROUGH THROUGH THE AFTERNOON HOURS.
COMBINATION OF MODERATE INSTABILITY AND INCREASING DEEP LAYER WLY FLOW
WILL SUPPORT A THREAT OF WIND DAMAGE AND ISOLATED LARGE HAIL WITH THE
STRONGER STORMS. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2
INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.  A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 29040. 

...THOMPSON



URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 488 
STORM PREDICTION CENTER NORMAN OK 
1137 AM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

CENTRAL AND EASTERN PENNSYLVANIA 
WESTERN NEW JERSEY                         
A SMALL PART OF SOUTHERN NEW YORK                           

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM NOON EDT UNTIL 600 PM
EDT. 

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 80 STATUTE MILES NORTH
AND SOUTH OF A LINE FROM 35 MILES WEST OF PHILIPSBURG PENNSYLVANIA TO 35
MILES EAST NORTHEAST OF ALLENTOWN PENNSYLVANIA. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

OTHER WATCH INFORMATION...  
CONTINUE...WW 0485...WW 0486...WW 
0487... 

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE/
INTENSITY THIS AFTERNOON ALONG PRE-FRONTAL TROUGH AND WITHIN THE WARM
SECTOR ACROSS PA.  SURFACE HEATING WILL RAISE SBCAPE VALUES TO NEAR 3000
J/KG...WHILE LOW-MID LEVEL WLY FLOW WILL STRENGTHEN TO 
40-50 KT IN ADVANCE OF THE AMPLIFYING ERN GREAT LAKES MID LEVEL TROUGH.
THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WINDS AND
LARGE HAIL. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2
INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.  A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 28040. 

...THOMPSON



URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 489 
STORM PREDICTION CENTER NORMAN OK 
200 PM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

EXTREME NORTHWEST CONNECTICUT        MOST OF MASSACHUSETTS                      
A SMALL PART OF SOUTHWEST MAINE         SOUTHERN NEW HAMPSHIRE                      
EAST AND SOUTHEAST NEW YORK               SOUTHERN VERMONT                            
ADJACENT COASTAL WATERS                     

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 215 PM UNTIL 900 PM
EDT. 

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 115 STATUTE MILES EAST
AND WEST OF A LINE FROM 20 MILES WEST SOUTHWEST OF WESTFIELD
MASSACHUSETTS TO 20 MILES EAST NORTHEAST OF LEBANON NEW HAMPSHIRE. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

OTHER WATCH INFORMATION...THIS SEVERE THUNDERSTORM WATCH REPLACES SEVERE
THUNDERSTORM WATCH NUMBER 486.  WATCH NUMBER 486 WILL NOT BE IN EFFECT
AFTER 215 PM EDT.  CONTINUE...WW 487...WW 488... 

DISCUSSION...MULTIPLE BANDS OF THUNDERSTORMS ALONG AND E OF THE COLD
FRONT IN NY WILL HAVE THE POTENTIAL TO PRODUCE DAMAGING WINDS AND
ISOLATED LARGE HAIL THROUGH THIS EVENING.  THE DAMAGING WIND THREAT
SHOULD INCREASE SOME IN THE NEXT FEW HOURS AS MID LEVEL FLOW INCREASES
TO 50-60 KT AND STORMS ENCOUNTER THE AXIS OF MODERATE INSTABILITY FROM
SE NY TO SRN ME. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2
INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.  A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 28040. 

...THOMPSON



URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 490 
STORM PREDICTION CENTER NORMAN OK 
220 PM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

SOUTHERN HALF OF MAINE
ADJACENT COASTAL WATERS

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 230 PM UNTIL 900 PM
EDT. 

HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 60 STATUTE MILES EAST
AND WEST OF A LINE FROM 40 MILES SOUTH OF AUGUSTA MAINE TO 55 MILES
NORTH NORTHEAST OF BANGOR MAINE. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

OTHER WATCH INFORMATION...  CONTINUE...WW 486...WW 487...WW 
488...WW 489... 

DISCUSSION...A NARROW SWATH OF MODERATE SURFACE-BASED INSTABILITY EXISTS
IMMEDIATELY INLAND FROM THE MAINE COAST...AND PRE-FRONTAL CONVECTION IS
APPROACHING THIS AREA FROM THE W.  IT APPEARS THE COMBINATION OF LOW-MID
LEVEL SPEED SHEAR...WHICH SHOULD INCREASE THROUGH THE AFTERNOON...AND
MODERATE INSTABILITY COULD SUPPORT A FEW THUNDERSTORMS WITH DAMAGING
WINDS AND ISOLATED LARGE HAIL. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 1
INCH EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 450.  MEAN STORM MOTION VECTOR 26035. 

...THOMPSON



URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 491 
STORM PREDICTION CENTER NORMAN OK 
243 PM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

CONNECTICUT                        
SOUTHEAST MASSACHUSETTS
NORTHERN NEW JERSEY                         
SOUTHEAST NEW YORK AND LONG ISLAND                           
RHODE ISLAND                       
ADJACENT COASTAL WATERS                     

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 300 PM UNTIL 900 PM
EDT. 

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 60 STATUTE MILES NORTH
AND SOUTH OF A LINE FROM 45 MILES NORTHWEST OF NEWARK NEW JERSEY TO 50
MILES SOUTHEAST OF NEW BEDFORD MASSACHUSETTS. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

OTHER WATCH INFORMATION...  CONTINUE...WW 486...WW 487...WW 
488...WW 489...WW 490... 

DISCUSSION...SEVERE THREAT EXPECTED TO INCREASE THIS AFTERNOON ACROSS
SRN NEW ENGLAND/SE NY/NRN NJ AS PRE-FRONTAL STORMS APPROACH FROM THE
W/NW.  MODERATE INSTABILITY /SBCAPE VALUES OF 2000-3000 J/KG/ AND
INCREASING MID LEVEL FLOW WILL SUPPORT A THREAT OF DAMAGING GUSTS AND
ISOLATED LARGE HAIL WITH THE STRONGER STORMS. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2
INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.  A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 28040. 

...THOMPSON



URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 492 
STORM PREDICTION CENTER NORMAN OK 
414 PM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

DISTRICT OF COLUMBIA 
DELAWARE                           
MARYLAND                           
NEW JERSEY                         
EXTREME SOUTHEAST OHIO
SOUTHERN AND SOUTHEASTERN PENNSYLVANIA                       
NORTHERN VIRGINIA                           
CENTRAL AND NORTHERN WEST VIRGINIA

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 430 PM UNTIL 900 PM
EDT. 

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 55 STATUTE MILES NORTH
AND SOUTH OF A LINE FROM 25 MILES NORTHWEST OF CHARLESTON WEST VIRGINIA
TO 25 MILES EAST SOUTHEAST OF TRENTON NEW JERSEY. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

OTHER WATCH INFORMATION...THIS SEVERE THUNDERSTORM WATCH REPLACES SEVERE
THUNDERSTORM WATCH NUMBER 487...SEVERE THUNDERSTORM WATCH NUMBER 488.
WATCH NUMBER 487...488 WILL NOT BE IN EFFECT AFTER 430 PM EDT.
CONTINUE...WW 489...WW 490...WW 491... 

DISCUSSION...PRE-FRONTAL SQUALL LINE CONTINUES TO MOVE SEWD...WITH
ADDITIONAL STORMS DEVELOPING AHEAD OF THE LINE IN NRN VA/MD. MODERATE
INSTABILITY REMAINS TO THE SE OF THE SQUALL LINE...WHILE VERTICAL SHEAR
SHOULD INCREASE WITH TIME TOWARD THE SE.  DAMAGING WINDS AND LARGE HAIL
WILL BE POSSIBLE WITH THE STRONGER STORMS. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2
INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.  A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 28040. 

...THOMPSON



URGENT - IMMEDIATE BROADCAST REQUESTED 
SEVERE THUNDERSTORM WATCH NUMBER 494 
STORM PREDICTION CENTER NORMAN OK 
617 PM EDT SUN JUL 1 2001 

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
PORTIONS OF 

   DISTRICT OF COLUMBIA
   SOUTHERN DELAWARE
   SOUTHEAST MARYLAND
   EASTERN VIRGINIA
   AND ADJACENT COASTAL WATERS
   
EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 630 PM UNTIL
MIDNIGHT EDT. 

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND
DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. 

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 45 STATUTE MILES EITHER
SIDE OF A LINE FROM 55 MILES WEST NORTHWEST OF RICHMOND VIRGINIA TO 60
MILES EAST SOUTHEAST OF DOVER DELAWARE. 

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE
FOR 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.  

SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. 

OTHER WATCH INFORMATION...  CONTINUE...WW 489...WW 490...WW 
491...WW 492...WW 493... 

DISCUSSION...LINE OF STRONG/SEVERE STORMS OVER NORTHEAST VA AND EASTERN
MD WILL DEVELOP SOUTHEASTWARD ACROSS THE DELMARVA REGION THIS EVENING.
DEGREE OF INSTABILITY AND SUFFICIENT SHEAR WILL PROMOTE LARGE HAIL AND
DAMAGING WINDS IN STRONGER CELLS. 

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2
INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.  A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 28035. 

...HART