Severe Thunderstorm Warning 40, NWS Boston/Norton, MA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1020 AM EDT SAT JUL 24 1999

DISC:  STILL APPEARS THAT SVR WX THREAT EXISTS FOR THIS AFTERNOON
AND EVENING.  CLOUD COVER REMAINS THICK ACROSS EASTERN ZONES...BUT
ANTICIPATE THINNING OUT DURING THE LATE MORNING/EARLY AFTERNOON
PERIOD.  LARGE CLEAR SPOTS ALREADY EXIST IN THE WRN ZONES WITH
TEMPERATURES UP TO NEAR 80 AT 10 AM.  PLENTY OF MOISTURE AVAILABLE
WITH TD TEMPS IN THE UPPER 60S AND LOWER 70S.  MODIFIED SOUNDINGS
THIS AM INDICATE SIGNIFICANT INSTABILITY IN -6 LI RANGE AND CAPE OF
AT LEAST 1400...POSSIBLY NEAR 2000.  PRECIPITABLE WATER NEAR 2.00
INCHES AND EHI OF 0.9 WAS ALSO INTERESTING.  HOWEVER...ALL OF THIS
SAID...THERE ARE SOME FACTORS WORKING AGAINST SEVERE WX.  WIND
FIELDS REMAIN RELATIVELY WEAK SFC/ALOFT (ALTHOUGH NO WORSE THAN
YSTERDAY AND WE HAD ISOLATED EVENTS) AND WAS SURPISED AT THE HEIGHT
OF THE WBZ BETWEEN 12500-13500 (ABOUT 3000 FT HIGHER THAN 00Z ETA
MODEL FCST).

FEELING IS THAT STORMS WILL DEVELOP/HEAD INTO WRN ZONES DURING THE
TIME OF PEAK HEATING AND CONTINUE TO SPREAD EAST INTO THE EVENING
HOURS. CAPE IS ACTUALLY A BIT LOWER IN STRONG VERTICAL MOTION
FIELD...THEN INCREASES DRAMATICALLY OVER ERN MA LATE IN THE DAY AND
EVENING.  NOT SURE IF THIS WILL BE THE CASE...BUT COULD MEAN THAT
GREATER ORGANIZATION AS TSTMS MOVE E AND CONTINUE TO DESTABILIZE WITH
DIURNAL HEATING.  XPCT THESE STORMS WILL PRODUCE FREQUENT LTG AND
BRING COPIOUS AMOUNTS OF RAINFALL WITH STREET FLOODING ETC.  WITH WBZ
VALUES SO HIGH...HAIL IS NOT LIKELY THE GREATEST THREAT...ALTHOUGH
ISOLATED LARGE HAIL CAN/T BE RULED OUT BY ANY MEANS.  ALSO DOWNBURST
WINDS EXCEEDING 50 KTS ARE POSSIBLE.

OVERALL...WILL CONTINUE WITH PRVS THINKING IN ZONES WITH ONLY MINOR
MODIFICATIONS.

MARINE...GRADIENT TIGHTENS AHEAD OF THIS AFTN/S TROF...ENUF TO
SUPPORT CRAFTIES ON THE SRN WATERS BASED ON GRADIENT AND CLIMO.
ERN WATERS NOT AS FAVORED AND SO WILL GO WITH ARND 20 EXCEPT
15-20 CLOSER TO SHORE.

ALY THANKS FOR COORD THIS AM...

.BOX...SCA CHH-WATCH HILL AND ADJACENT BAYS/SOUNDS.

DCY

CTZ002>004-MAZ002>024-NHZ011-012-RIZ001>007-242021-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TAUNTON MA
1119 AM EDT SAT JUL 24 1999

...SOME THUNDERSTORMS ACROSS SOUTHERN NEW ENGLAND THIS AFTERNOON AND
EVENING MAY BECOME SEVERE...

WARM...VERY MOIST AND UNSTABLE AIR WILL COMBINE WITH AN APPROACHING
COLD FRONT TO PRODUCE STRONG THUNDERSTORMS ACROSS SOUTHERN NEW
ENGLAND THIS AFTERNOON AND TONIGHT.  THESE STORMS WILL LIKELY BE
ACCOMPANIED BY FREQUENT LIGHTNING...STRONG GUSTY WINDS AND POSSIBLY
LARGE HAIL.  TORRENTIAL RAINFALL ACCOMPANYING SOME OF THESE STORMS
WILL CREATE LOCALIZED STREET FLOODING AND RAPID RISES ON SMALL
STREAMS.

THE GREATEST RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON WILL EXTEND
FROM THE CONNECTICUT VALLEY AND CENTRAL HILLS INTO SOUTHWEST NEW
HAMPSHIRE...AN AREA WEST OF A LINE FROM NASHUA NEW HAMPSHIRE THROUGH
WORCESTER MASSACHUSETTS TO NORWICH CONNECTICUT.  THIS RISK OF SEVERE
WEATHER WILL SPREAD EAST ACROSS THE REMAINDER OF THE REGION
THROUGH THIS EVENING.

THE BEST CHANCE OF SEVERE THUNDERSTORMS WILL OCCUR DURING THE
TIME OF PEAK AFTERNOON HEATING FROM 2 PM AND CONTINUE THROUGH
9 PM.  HOWEVER...ADDITIONAL SHOWERS AND THUNDERSTORMS ARE
POSSIBLE DURING THE OVERNIGHT.

SPOTTERS AND AMATEUR RADIO OPERATORS SHOULD BE PREPARED TO RELAY
REPORTS LATER TODAY SHOULD SEVERE WEATHER DEVELOP.

DCY