SWODY1
SPC AC 072000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT TUE JUL 07 2009
VALID 072000Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS FOR PORTIONS OF THE NRN
PLAINS/UPPER MIDWEST...
...THERE IS A SLGT RISK OF SVR TSTMS FOR PORTIONS OF THE
NORTHEAST...
...NRN/CNTRL PLAINS...
UNCERTAINTY REMAINS OVER THE AREAL COVERAGE...INTENSITY AND MODE OF
TSTM ACTIVITY THROUGH TONIGHT GIVEN THE PRESENCE OF WEAK
MID/UPPER-LEVEL RIDGING. THUS...HAVE REMOVED HIGHER SIGNIFICANT HAIL
PROBABILITIES. WILL STILL MAINTAIN HIGHER HAIL/WIND PROBABILITIES
ACROSS SERN SD WHERE ONGOING CLUSTER OVER E-CNTRL SD MAY
EVOLVE/DEVELOP SEWD...WITH ADDITIONAL DEVELOPMENT POSSIBLE INVOF
MESOLOW NEAR SERN SD.
...NORTHEAST...
PROBABILITIES ADJUSTED TO REFLECT THE ONGOING MARGINALLY SEVERE
HAIL/LOCALLY DAMAGING WIND EVENT THAT CONSISTS PRIMARILY OF TWO
AREAS OF CONCENTRATED TSTM ACTIVITY. THE INITIAL CLUSTER OVER SRN
NEW ENGLAND SHOULD MOVE OFFSHORE BY 21-22Z...WHILE ADDITIONAL
SCATTERED TSTMS ARE CURRENTLY APPROACHING THE HUDSON VALLEY. SOME
RECOVERY HAS OCCURRED BETWEEN THESE TWO AREAS AND SHOULD BE THE MAIN
FOCUS FOR ADDITIONAL SEVERE TSTMS THIS AFTERNOON.
ELSEWHERE...MINOR CHANGES MADE TO TSTM/5% SEVERE PROBABILITIES BASED
ON OBSERVATIONAL TRENDS. PLEASE REFER TO LATEST WATCHES AND MCDS FOR
MORE SPECIFIC SHORT-TERM FORECASTS.
..GRAMS/DIAL.. 07/07/2009
.PREV DISCUSSION... /ISSUED 1120 AM CDT TUE JUL 07 2009/
...NORTHEAST STATES...
A FLAT UPPER TROUGH IS PRESENT THIS MORNING OVER THE NORTHEAST
UNITED STATES...WHILE AN UPPER RIDGE HOLDS FIRM ACROSS THE SOUTHERN
ROCKIES AND PLAINS. WATER VAPOR IMAGERY SUGGESTS A RATHER POTENT
MID LEVEL SPEED MAX IS ROTATING ACROSS NY/PA AND INTO SOUTHERN NEW
ENGLAND THIS AFTERNOON. POCKETS OF DAYTIME HEATING AND STEEP LAPSE
RATES WILL YIELD MODERATE INSTABILITY LATER TODAY WITH MUCAPE VALUES
OF 1000-2000 J/KG. COOL TEMPERATURES ALOFT AND SUFFICIENT VERTICAL
SHEAR WILL PROMOTE ORGANIZED THUNDERSTORMS CAPABLE OF LARGE HAIL AND
GUSTY WINDS. MULTIPLE BANDS OF STRONG/SEVERE STORMS ARE POSSIBLE AS
ACTIVITY REDEVELOPS BEHIND INITIAL ACTIVITY MOVING ACROSS NEW
ENGLAND.
...NORTHERN PLAINS AND UPPER MIDWEST...
CLUSTER OF THUNDERSTORMS HAS PERSISTED OVERNIGHT ACROSS MT/ND...AND
IS NOW BEGINNING TO AFFECT PARTS OF SD. THESE STORMS ARE EXPECTED
TO INTENSIFY LATER THIS AFTERNOON AND SPREAD SOUTHEASTWARD INTO
PARTS OF SD/IA/NEB/MN. WEAK UPPER RIDGING ACROSS THE AREA LIMITS
CONFIDENCE IN AREAL COVERAGE OF SEVERE STORMS TODAY.
HOWEVER...MODERATE TO STRONG INSTABILITY AND PERSISTENCE OF
CONVECTIVE CLUSTER SUGGESTS ENHANCED SEVERE PROBABILITIES REMAIN
WARRANTED ACROSS PARTS OF THE AREA. PLEASE REFER TO SWOMCD NUMBER
1472 FOR FURTHER DETAILS.
...KS/OK...
A SMALL CLUSTER OF THUNDERSTORMS HAS DEVELOPED THIS MORNING NEAR
ICT. THESE STORMS APPEAR TO BE ASSOCIATED WITH A WEAK MID LEVEL
VORT MAX THAT AIDED CONVECTIVE DEVELOPMENT YESTERDAY AFTERNOON OVER
CENTRAL CO. THIS FEATURE WILL CONTINUE TO DRIFT EAST-SOUTHEASTWARD
TODAY AND MAY HELP TO INITIATE FURTHER CONVECTION. 12Z NAM AND
WRF-NMM RUNS SUGGEST AN INCREASED RISK OF THUNDERSTORMS ACROSS PARTS
OF CENTRAL OK...SO HAVE ADJUSTED THIS OUTLOOK ACCORDINGLY.
...SOUTHERN HIGH PLAINS...
AT LEAST ISOLATED THUNDERSTORMS ARE POSSIBLE ONCE AGAIN TODAY ALONG
AN AXIS FROM EASTERN CO/WESTERN NEB INTO WEST TX. UPPER RIDGING
SHOULD LIMIT EXTENT OF STORMS. HOWEVER...ANY STORM THAT DOES
DEVELOP WILL POSE A RISK OF HAIL AND GUSTY WINDS.
...MT...
STRONG SOUTHWEST FLOW ALOFT WILL MAINTAIN FAVORABLE VERTICAL SHEAR
ACROSS MUCH OF MT TODAY. REMNANT DEWPOINTS IN THE 40S OVER THE
MOUNTAINS OF SOUTHWEST MT ALONG WITH STRONG HEATING MAY LEAD TO
ISOLATED AFTERNOON THUNDERSTORMS. HAIL WILL BE POSSIBLE IN THE
STRONGER CELLS...ALTHOUGH ORGANIZED SEVERE WEATHER IS NOT CURRENTLY
ANTICIPATED.
...SOUTHEAST STATES...
SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON ALONG REMNANT
BOUNDARY EXTENDING ACROSS THE GULF COAST STATES INTO THE SOUTHEAST.
A FEW WET MICROBURSTS ARE POSSIBLE IN THE STRONGEST CELLS.
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