Sunday, August 10, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 100553
SWODY1
SPC AC 100550

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT SUN AUG 10 2008

VALID 101200Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MIDDLE ATLANTIC TO
SRN NEW ENGLAND...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN HIGH PLAINS...

...ERN U.S...

IMPRESSIVE MID LEVEL CYCLONE IS EXPECTED TO DIG SEWD ACROSS THE
LOWER GREAT LAKES REGION INTO PA BY THE END OF THE PERIOD. THIS
FEATURE IS WELL IDENTIFIED ON EARLY MORNING SATELLITE IMAGERY
SUPPORTING THE LATEST MODEL GUIDANCE. THERMAL PROFILES WILL COOL
CONSIDERABLY ACROSS THE MIDDLE ATLANTIC WHERE STRONGEST DEEP LAYER
SHEAR IS ALSO EXPECTED TO OCCUR ALONG SRN PERIPHERY OF DEEP LOW.
FORECAST SOUNDINGS ALONG THE MIDDLE ATLANTIC COAST SUGGEST ANY
STORMS THAT DEVELOP FROM THE NC/VA BORDER...NWD INTO SERN PA/SRN NJ
COULD CERTAINLY ROTATE GIVEN SFC-6KM SHEAR VALUES ON THE ORDER OF
35KT. LATEST THINKING IS BOUNDARY LAYER WILL WARM RAPIDLY BY MID
DAY WHICH WILL RESULT IN EARLY CONVECTIVE DEVELOPMENT...ESPECIALLY
ACROSS UPSTATE NY...SWD INTO CNTRL PA...ALONG/AHEAD OF ADVANCING
WIND SHIFT. THIS ACTIVITY SHOULD EXPAND IN AREAL COVERAGE EAST OF
THE MOUNTAINS FROM THE CAROLINAS...NWD INTO NEW ENGLAND BY MID
AFTERNOON...ESPECIALLY GIVEN THE DEEPENING CYCLONIC FLOW AND
INCREASING LARGE SCALE ASCENT. COOL THERMAL PROFILES FAVOR HAIL
WITH STRONGER UPDRAFTS...WHILE LOCALLY DAMAGING WINDS MAY ACCOMPANY
SUPERCELL STRUCTURES ACROSS THE MIDDLE ATLANTIC. CONVECTION MAY
LINGER WELL INTO THE OVERNIGHT HOURS AHEAD OF ADVANCING FRONTAL
BOUNDARY ACROSS NEW ENGLAND.

...NRN HIGH PLAINS...

UPPER RIDGE WILL BE SLOW TO BREAK DOWN ACROSS THE HIGH
PLAINS...THOUGH IT APPEARS A WEAK SHORTWAVE TROUGH MAY TOP THE RIDGE
ACROSS ERN MT INTO THE WRN DAKOTAS. THIS FEATURE WOULD CERTAINLY
ENHANCE CONVECTIVE POTENTIAL DURING THE LATE AFTERNOON/EVENING HOURS
AS INHIBITION IS REMOVED DUE TO STRONG HEATING. FORECAST SOUNDINGS
ACROSS THE SLIGHT RISK REGION INDICATE SUBSTANTIAL VEERING WITHIN
THE COLUMN...WITH CONVERGENT SELY LOW LEVEL FLOW EXPECTED TO AID
UPDRAFT STRENGTH/LONGEVITY. ALTHOUGH MID LEVEL FLOW IS SOMEWHAT
WEAK...STORM ROTATION MAY BE NOTED AND A FEW WEAK SUPERCELLS COULD
CERTAINLY DEVELOP BY EARLY EVENING. LARGE HAIL AND LOCALLY STRONG
WIND GUSTS MAY ACCOMPANY SUPERCELL STRUCTURES. OTHERWISE...MULTIPLE
THUNDERSTORM CLUSTERS MAY EVOLVE DURING THE EARLY EVENING HOURS
AIDED BY WEAK LARGE SCALE SUPPORT AHEAD OF SHORTWAVE TROUGH.

...SERN OK/ARKLATEX...

MODELS ARE IN FAIRLY GOOD AGREEMENT THAT ONGOING MCS ACROSS SERN
KS/NERN OK/AR WILL BE LONG LIVED AND LIKELY ONGOING AT THE BEGINNING
OF THE PERIOD...ESPECIALLY GIVEN THE NOTABLE LLJ THAT SHOULD EXTEND
FROM N TX INTO NWRN AR AT 12Z. CONVECTIVE OUTFLOW AND A GRADUAL SWD
SHIFT TO LARGER SCALE FRONTAL BOUNDARY WILL RESULT IN FOCUSED LOW
LEVEL CONVERGENCE NEAR THE RED RIVER OF OK/TX BY LATE AFTERNOON.
SFC TEMPERATURES WILL ONCE AGAIN SOAR TO NEAR 100F SOUTH OF THE
FRONT RESULTING IN RELATIVELY HIGH BASED STRUCTURES. GIVEN THE HIGH
PRECIPITABLE WATER CONTENT ACROSS THIS REGION THERE APPEARS TO BE
SOME THREAT FOR ISOLATED DAMAGING DOWNBURSTS. AT THIS TIME WILL
MAINTAIN LOW PROBABILITIES FOR WIND...HOWEVER AN UPGRADE MAY BE
WARRANTED IN LATER OUTLOOKS IF IT BECOMES MORE CLEAR THAT AN
ORGANIZED ZONE OF CONVECTION COULD DEVELOP.

..DARROW/HURLBUT.. 08/10/2008

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