SPC AC 031725
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1225 PM CDT MON SEP 03 2012
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER GREAT LAKES TO
THE CENTRAL PLAINS...
...UPPER GREAT LAKES TO CENTRAL PLAINS...
SIGNIFICANT HEIGHT FALLS WILL SPREAD ACROSS SRN MB INTO THE NRN
PLAINS/UPPER MS VALLEY DURING THE LATTER HALF OF THE PERIOD AS A
STRONG MID LEVEL SPEED MAX...H5 FLOW IN EXCESS OF 50KT...DIGS INTO
ERN ND/NRN MN BY 05/00Z. SUBSEQUENT DIFFLUENT HIGH LEVEL FLOW WILL
SPREAD DOWNSTREAM INTO THE UPPER GREAT LAKES REGION WHICH SHOULD
ENCOURAGE ASCENT ALONG ADVANCING SFC BOUNDARY. LATEST NAM/GFS MODEL
GUIDANCE SUGGEST STRONG BOUNDARY LAYER HEATING WILL CONTRIBUTE TO
DESTABILIZATION BY LATE AFTERNOON SUCH THAT FRONTAL CONVECTION IS
LIKELY BY PEAK HEATING. ONE NOTABLE DIFFERENCE BETWEEN THE TWO
MODELS IS THE NAM IS MORE CONVERGENT AT LOW LEVELS ACROSS WI DUE TO
A PRE-FRONTAL WIND SHIFT AND A SLIGHTLY MORE PROGRESSIVE UPPER
TROUGH. IT/S NOT ENTIRELY CLEAR IF THIS FASTER SOLUTION IS ACCURATE
BUT WILL INCREASE SEVERE PROBS ACROSS THE UPPER GREAT LAKES TO
ACCOUNT FOR THE FASTER NAM SOLUTION. OTHERWISE...SCATTERED
CONVECTION SHOULD DEVELOP SWWD ALONG THE WIND SHIFT ACROSS SRN
MN/NWRN IA INTO THE CNTRL PLAINS BY EARLY EVENING. MORE THAN
ADEQUATE DEEP LAYER SHEAR WILL EXIST FOR ORGANIZED MULTI-CELL TSTMS
AND PERHAPS EVEN A FEW SLOW MOVING SUPERCELLS...ESPECIALLY ACROSS
THE MID MO VALLEY. LARGE HAIL AND LOCALLY DAMAGING WINDS ARE
POSSIBLE WITH FRONTAL CONVECTION INTO THE LATE EVENING HOURS.
....CENTRAL GULF STATES...
NLY FLOW WILL DEEPEN/STRENGTHEN ACROSS THE CNTRL GULF STATES ON THE
BACK SIDE OF TROUGH FROM THE REMNANTS OF ISAAC. WHILE THE MAJORITY
OF CONVECTION SHOULD BE NOTED AHEAD OF THE TROUGH AXIS FROM THE ERN
GULF STATES INTO THE APPALACHIANS...ANY ISOLATED STORMS THAT DEVELOP
ACROSS ERN MS/WRN AL WILL DO SO WITHIN A STEEPER LAPSE RATE
ENVIRONMENT THAT WILL PROVE MORE FAVORABLE FOR UPDRAFT ORGANIZATION.
FOR THIS REASON HAVE ADDED 5 PERCENT SEVERE PROBS TO ACCOUNT FOR
ISOLATED DAMAGING WIND GUSTS.
..DARROW.. 09/03/2012
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
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