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Storm Information: Severe Weather Discussions

Severe Weather Discussions by PHLweather

Severe weather discussions are geographical discussions that highlight certain severe weather events. For more information on how these products are produced, e-mail us at phlweather@lycos.com.

VALID SWDs

042802-0935 severe thunderstorm outbreak.

SWD Color Codes

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042802-0935
Severe thunderstorm outbreak

Valid for: Berks, Bucks, Carbon, Chester, Delaware, Lancaster, Lehigh, Monroe, Montgomery, Northampton, Philadelphia, Pike and Schuylkill PA. Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, Hunterdon, Mercer, Middlesex, Monmouth, Morris, Ocean, Salem, Someset and Warren NJ. Kent, New Castle and Sussex DE. Caroline, Cecil and Kent MD. Delaware Bay. Offshore waters from Sandy Hook, NJ to Fenwick Island, DE out 20nm.
Including the cities of: Allentown, Bethlehem, Chester, Doylestown, Lancaster, Millersville, Mount Pocono, Norristown, Philadelphia, Pottsville, Reading and West Chester. Atlantic City, Camden, Cape May, Cherry Hill, Clinton, Flemington, Lambertville, Morristown, Ocean City, Phillipsburg, Princeton, Salem, Sussex, Trenton and Wrightstown NJ. Dover, Newark, Rehohboth Beach and Wilmington, DE. Chestertown and Elkton MD.

Issued: 9:35am - April 28, 2002
Expires: 2:35pm - April 28, 2002

...OUTBREAK OF SEVERE THUNDERSTORMS EXPECTED LATER THIS AFTERNOON AND EVENING...

A POWERFUL LOW PRESSURE SYSTEM IS CURRENTLY LOCATED ACROSS THE UPPER OHIO VALLEY. A COLD FRONT EXTENDS DOWN FROM THIS LOW THROUGH THE OHIO AND TENNESSEE RIVER VALLEY WITH A WARM FRONT EXTENDING OUT EASTWARD ACROSS SOUTHERN PENNSYLVANIA. THIS WARM FRONT WILL LIFT NORTH THROUGH THE REGION AND STALL OUT ACROSS THE PENNSYLVANIA-NEW YORK BORDER. AS THE COLD FRONT APPROACHES FROM THE WEST AND INTERACTS WITH THE INCREASINGLY UNSTABLE AIR...SEVERE THUNDERSTORMS ARE A LIKELIHOOD BY LATE AFTERNOON.

RAIN AND COOL WEATHER NORTH OF THE WARM FRONT WILL BE SHROUDED OUT AS IT LIFTS NORTH LATER THIS MORNING...AND SOME SUNSHINE IS POSSIBLE BY EARLY AND MID AFTERNOON. THIS COMBINED WITH GUSTY SOUTH TO SOUTHWEST WINDS WILL ONLY ACT TO CREATE A MORE UNSTABLE ENVIRONMENT OUT AHEAD OF THE COLD FRONT. NUMEROUS SHOWERS AND THUNDERSTORMS WILL BEGIN TO DEVELOP BY MIDDAY IN WESTERN PENNSYLVANIA. MANY STORMS WILL BECOME SEVERE WITH FAVORABLE CONDITIONS IN CENTRAL AND EASTERN PENNSYLVANIA.

THE RISK OF SEVERE THUNDERSTORMS WILL BE GREATEST AFTER 4PM ACROSS EASTERN PENNSYLVANIA AND NORTHWEST NEW JERSEY AND AFTER 6PM IN CENTRAL AND SOUTHERN NEW JERSEY AND THE DELMARVA. THE NUMEROUS THUNDERSTORMS WILL WARRANT THIS AN OUTBREAK WITH A GOOD RISK OF DAMAGING WINDS...LARGE HAIL...FREQUENT CLOUD-TO-GROUND LIGHTNING. IN ADDITION...WITH SEVERAL AXIS OF CHANGING WINDS AT DIFFERENT LEVELS OF THE ATMOSPHERE...STRONGER SUPERCELL THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE TORNADOES. THE BEST RISK FOR SUPERCELL STORMS AND TORNADOES WILL BE TO THE NORTHWEST OF PHILADELPHIA.

THIS IS A POTENTIALLY DANGEROUS SITUATION. THOSE IN THE ADVISED AREA SHOULD REVIEW TORNADO AND SEVERE THUNDERSTORM SAFETY RULES AND BE PREPARED FOR IMMEDIATE ACTION SHOULD THREATENING WEATHER APPROACH YOUR AREA OR A WARNING BE ISSUED. SEVERE WATCH BOXES WILL PROBABLY BE ISSUED LATER THIS AFTERNOON AND EVENING.

THIS DISCUSSION WILL BE UPDATED BY 235 PM EST WITH THE LATEST INFORMATION.

Technical
SWATH OF RAIN TO PUSH EWD OUT OF RGN BY MIDDAY. CLOUD BREAKS BY 1PM WITH RAPIDLY WARMING TEMPS ON SSW WINDS. TEMPS IN THE 70S...DEWPTS IN THE 50S AND 60S WILL CREATE SB AND MUCAPE OF 1000 TO 2000 J/KG. LI AS LOW AS -7 PSBL WITH HELICITIES IN THE 500+ RANGE GIVING THREAT FOR DAMAGING TORNADOES. PW TABLES UP NEAR 4CM GIVE POTENTIAL FOR MANY PLACES TO SEE 2 IN OR MORE OF RAIN IN CONV ACTIVITY COMBINED WITH RAIN TOTALS FROM EARLIER THIS AM.

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