DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 081729
SWODY2
SPC AC 081727

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1227 PM CDT SAT JUN 08 2013

VALID 091200Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID
MS/LOWER OH VALLEYS TO NRN AR/WRN TN...

...SYNOPSIS...
AT 12Z SUNDAY...A MID AND UPPER LEVEL TROUGH AXIS WILL EXTEND N-S
ACROSS THE ERN PORTION OF THE GREAT PLAINS WITH THIS FEATURE
REMAINING PROGRESSIVE AS STRONG 250/500 MB WLY JETS SHIFT EWD ALONG
THE NWRN TO NORTH CENTRAL U.S./CANADIAN BORDER. MODELS AGREE THE
UPPER LOW ATTENDANT TO THIS SYSTEM WILL WEAKEN...AND COULD BECOME
CLOSED OFF AT TIMES AS IT MOVES FROM NWRN IA TO THE LOWER OH VALLEY.
THE SURFACE LOW WILL SUBSEQUENTLY WEAKEN AS IT TRACKS FROM NWRN IA
TO CENTRAL IL BY 12Z MONDAY. A TRAILING COLD FRONT WILL ADVANCE
ESEWD FROM THE CENTRAL PLAINS THROUGH THE LOWER MO/MID MS
VALLEYS...WITH THE SRN EXTENT BECOMING QUASI-STATIONARY E-W OVER
CENTRAL/NRN OK. A N-S PRE-FRONTAL TROUGH/WIND SHIFT MAY BE THE
PRIMARY FOCUS FOR SUNDAY AFTERNOON/EVENING CONVECTION FROM THE MID
SOUTH TO THE MID MS/LOWER OH VALLEYS...WHILE A WARM FRONT LIFTS NEWD
THROUGH THE OH VALLEY. TSTMS ARE FORECAST ACROSS A LARGE PART OF
THE ERN U.S... GENERALLY SOUTH OF THE UPPER GREAT LAKES TO NEW
ENGLAND...WITH CONVECTION LIKELY BEGINNING EARLY IN THE
PERIOD...GIVEN THE PRESENCE OF GENERALLY WEAK SURFACE BASED
INHIBITION.

...NRN AR/WRN TN TO MID MS/LOWER OH VALLEYS...
ALTHOUGH STRONGER MIDLEVEL WINDS ARE EXPECTED TO REMAIN ALONG THE
WRN PERIPHERY OF THE PROGRESSIVE MIDWEST TROUGH...A BROAD CORRIDOR
OF 35-50 KT S/SWLY 500 MB FLOW IS EXPECTED ACROSS THE MID MS TO
OH/TN VALLEYS ON SUNDAY. DESPITE SURFACE HEATING AND MOISTURE
RETURN ACROSS THE WARM SECTOR...STEEPER MIDLEVEL LAPSE RATES
REMAINING WEST OF THE UPPER TROUGH WILL LIMIT STRONGER INSTABILITY
FROM DEVELOPING EAST OF THE COLD FRONT. MLCAPE VALUES SHOULD BE AOB
1500 J/KG SUNDAY AFTERNOON. CONVECTION SHOULD DEVELOP EARLY IN THE
PERIOD...AS SURFACE HEATING DIMINISHES INHIBITION WITHIN A WEAKLY
CAPPED WARM SECTOR. ADDITIONAL STORMS SHOULD ALSO RE-INTENSIFY ALONG
THE ERN EXTENT OF ONGOING STORMS FROM PARTS OF THE OZARKS TO THE
MID-UPPER MS VALLEY. STRONGER STORMS MAY BE LOCATED ALONG THE N-S
PRE-FRONTAL TROUGH FROM IL TO NERN AR/WRN TN AND THE COLD FRONT INTO
MO WHERE LOW LEVEL CONVERGENCE WILL BE GREATER. GENERALLY WEAK
LOWER TROPOSPHERIC WINDS WILL BE A LIMITING FACTOR FOR A TORNADO
THREAT...WHILE EFFECTIVE BULK SHEAR OF 25-35 KT SUGGESTS MULTICELLS
AND A FEW SUPERCELLS CAN BE EXPECTED IN THE AFTERNOON TO EARLY
EVENING. DAMAGING WINDS AND HAIL WILL BE THE PRIMARY THREATS.

...CENTRAL/NERN TX TO SRN AR/NRN MS...
DESPITE WEAKER FORCING WITH SWD EXTENT...STRONGER INSTABILITY AND
EFFECTIVE BULK SHEAR UP TO 25-30 KT SUGGEST MULTICELL STORMS WILL BE
POSSIBLE ALONG A PRE-FRONTAL WIND SHIFT EXTENDING FROM ERN-SRN AR
INTO CENTRAL TX SUNDAY AFTERNOON. A FEW STRONGER-SEVERE STORMS
COULD BE CAPABLE OF PRODUCING LOCALLY DAMAGING WINDS AND/OR
HAIL...AND THUS RESULTS IN A SWWD EXTENSION OF 5 PERCENT SEVERE
PROBABILITIES.

...SOUTHEAST STATES....
WHILE THE MAIN UPPER TROUGH MOVES ACROSS THE UPPER MIDWEST...MODELS
CONTINUE TO DEPICT SMALLER-SCALE DISTURBANCES ALOFT PROGRESSING NEWD
ACROSS THE SERN U.S. ON THE SRN-ERN FRINGE OF BROAD CYCLONIC FLOW.
WITH A MOIST/DESTABILIZING AFTERNOON AIR MASS...EXPECT ASCENT
ASSOCIATED WITH THESE UPPER FEATURES TO SUPPORT DEVELOPMENT OF
SEVERAL BANDS OF NEWD-MOVING TSTMS. WHILE NOT PARTICULARLY
STRONG...SLIGHTLY ENHANCED SWLYS ALOFT MAY SUPPORT SOME ORGANIZATION
WITH A FEW CLUSTERS OF CONVECTION...POTENTIALLY PRODUCING A THREAT
FOR LOCALLY GUSTY/DAMAGING WINDS AND POSSIBLY MARGINAL HAIL.

..PETERS.. 06/08/2013

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