SPC AC 050731
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0231 AM CDT TUE MAY 05 2009
VALID 071200Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ERN PART OF THE SRN
PLAINS TO THE OH/TN VALLEYS...
...SYNOPSIS...
DETERMINISTIC MODELS ARE IN GENERAL AGREEMENT INDICATING A BROAD
CYCLONIC FLOW REGIME /50-70 KT MID LEVEL WINDS/ EXTENDING FROM THE
PACIFIC NW THROUGH THE CENTRAL PLAINS AND OH VALLEY/MID SOUTH TO
NERN STATES ON THURSDAY. A SHORTWAVE TROUGH...INITIALLY CENTERED
OVER SRN MANITOBA AT 12Z THURSDAY...SHOULD UNDERGO SOME
AMPLIFICATION AS IT TRACKS EWD ONTARIO/GREAT LAKES REGION. ALTHOUGH
MODELS DIFFER WITH THIS SYSTEM...THEY TEND TO AGREE WITH NEXT
UPSTREAM SHORTWAVE TROUGH THAT SHOULD AMPLIFY ESE TOWARD THE NRN
PLAINS BY 12Z FRIDAY.
IN THE LOW LEVELS...MODELS TEND TO AGREE THAT A SURFACE TROUGH
SHOULD EXTEND FROM THE WRN GREAT LAKES SWWD THROUGH MO TO KS AT 12Z
THURSDAY. THIS TROUGH WILL PROGRESS E/SEWD AND SHOULD EXTEND FROM
THE OH VALLEY SWWD THROUGH THE MID SOUTH/AR INTO OK...POSSIBLY N TX
BY 12Z FRIDAY.
...OH VALLEY SWWD THROUGH MID SOUTH TO SRN PLAINS...
A COUPLE OF CLUSTERS OF TSTMS SHOULD BE ONGOING EARLY THURSDAY
MORNING...1. ACROSS THE LOWER OH VALLEY AND THE 2. ACROSS THE
CENTRAL PLAINS. SWLY LOW LEVEL FLOW WILL DEVELOP FROM AR INTO THE
OH VALLEY ON DAY 3 RESULTING IN NEWD MOISTURE RETURN AND SURFACE
DEWPOINTS IN THE LOWER 60S REACHING SWRN OH BY LATE THURSDAY
AFTERNOON. SURFACE HEATING SHOULD BE STRONGEST FROM PARTS OF OK
ENEWD THROUGH AR/SRN MO TO TN/OH VALLEYS. MODERATE INSTABILITY WILL
DEVELOP AHEAD OF THE SURFACE TROUGH FROM IND/OH SWWD THROUGH
KY/TN...WHILE A VERY UNSTABLE AIR MASS IS LIKELY FROM AR INTO OK
WITH MLCAPE 2500-3500 J/KG. THE HIGHEST MLCAPE VALUES SHOULD BE
LOCATED IN CENTRAL OK/N TX WHERE MOISTURE WILL BE GREATER.
STRONG EFFECTIVE BULK SHEAR WILL ALREADY BE IN PLACE ACROSS THE SRN
PLAINS AT THE START OF DAY 3...WITH EFFECTIVE BULK SHEAR INCREASING
FROM W-E INTO THE OH/TN VALLEYS AS STRONG MID LEVELS WINDS SPREAD
EWD AND SWLY LOW LEVEL WINDS STRENGTHEN. THIS IS EXPECTED TO
SUPPORT ORGANIZED SEVERE STORMS FROM SRN MO/ERN OK/AR INTO THE OH/TN
VALLEYS FROM LATE MORNING INTO THE AFTERNOON. FARTHER W INTO
CENTRAL OK/N TX...A DRY LINE IS EXPECTED TO MIX EWD REACHING
WRN...POSSIBLY CENTRAL OK TO CENTRAL TX THURSDAY AFTERNOON. A
STRONGER CAP ACROSS THIS REGION SHOULD TEND TO INHIBIT SURFACE BASED
DEVELOPMENT UNTIL LATE AFTERNOON OR EARLY EVENING. IF STORMS CAN
DEVELOP ACROSS PARTS OF CENTRAL OK INTO N TX...THE DEGREE OF
INSTABILITY/SHEAR VALUES WOULD SUPPORT SUPERCELLS PRODUCING
TORNADOES AND LARGE HAIL.
INCREASING SLY LLJ VEERING THURSDAY NIGHT WILL SHOULD SUPPORT
ANOTHER MCS ACROSS PARTS OF OK/KS INTO THE OZARKS...WITH THE
POTENTIAL FOR ISOLATED HAIL WITH THESE ELEVATED STORMS.
..PETERS.. 05/05/2009
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z