DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 031844
SWODY2
SPC AC 031843

DAY 2 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0143 PM CDT WED JUL 03 2013

VALID 041200Z - 051200Z

...NO SVR TSTM AREAS FORECAST...

CORRECTED FOR THUNDER GRAPHIC

...CNTRL GULF COAST/TN VALLEY/OH VALLEY...

LARGE SCALE PATTERN IS EXPECTED TO CHANGE LITTLE INTO THE DAY2
PERIOD WITH DOMINANT UPPER RIDGE HOLDING ACROSS THE SWRN U.S. AND
TROUGHING ANCHORED NEAR THE MS VALLEY. OVER THE LAST FEW DAYS A
BELT OF STRONGER MID LEVEL FLOW HAS EXTENDED FROM THE CNTRL GULF
STATES...ARCING ANTICYCLONICALLY ACROSS THE TN/OH VALLEY INTO NEW
ENGLAND. CONVECTION THAT HAS EVOLVED WITHIN THIS CORRIDOR OF
STRONGER SHEAR HAS TAKEN ON MULTI-CELL CHARACTERISTICS AND AT TIMES
EVEN PRODUCED GUSTY DOWNDRAFTS. WHILE THE LARGE SCALE PATTERN IS
NOT EXPECTED TO CHANGE DRAMATICALLY...ONE SIGNIFICANT DIFFERENCE
WILL EMERGE THURSDAY. LLJ IS EXPECTED TO INCREASE MARKEDLY ACROSS
AL INTO ERN TN/KY WHERE 850MB FLOW COULD EXCEED 45KT. LATEST MODEL
GUIDANCE CONTINUES TO SUGGEST WIDESPREAD CONVECTION...SOME OF IF
DEEP ENOUGH TO PRODUCE LIGHTNING...WILL EVOLVE WITHIN THIS CORRIDOR
OF STRONGER FLOW. WHILE INSTABILITY SHOULD PROVE WEAK...WITH LAPSE
RATES LIKELY NEAR PSEUDO-ADIABATIC...LOW-MID LEVEL SHEAR MAY ALLOW
FOR WEAK SUPERCELL STRUCTURES TO EVOLVE WITHIN BROADER CONVECTIVE
SHIELD. IF SUFFICIENT INSTABILITY CAN DEVELOP ISOLATED WEAK
TORNADOES COULD BE NOTED. FOR NOW HAVE OPTED TO EXPAND 5 PERCENT
SEVERE PROBS TO BETTER REFLECT EXPECTED CORRIDOR OF CONVECTION.

FARTHER NORTH...WEAK BOUNDARY LAYER HEATING ACROSS THE OH VALLEY
INTO UPSTATE NY COULD ENHANCE A FEW ROBUST UPDRAFTS/DOWNDRAFTS.
LOCALLY STRONG WINDS COULD ACCOMPANY SOME OF THIS ACTIVITY.

...MT...

UPPER RIDGE WILL FLATTEN A BIT ACROSS THE NRN ROCKIES INTO THE DAY2
PERIOD AS HEIGHTS FALL AHEAD OF PROGRESSIVE SHORT-WAVE TROUGH.
STRONG HEATING ACROSS THE PLAINS OF CNTRL MT SHOULD COINCIDE WITH
WEAK LOW LEVEL CONFLUENCE ZONE DURING THE AFTERNOON HOURS WHICH
COULD AID A FEW STRONG THUNDERSTORMS. FORECAST SOUNDING AT LWT BY
18Z SUGGESTS CONVECTIVE TEMPERATURES WILL BE REACHED BY MID
AFTERNOON. WITH SBCAPE IN EXCESS OF 2000 J/KG AND 30KT WLY 500MB
FLOW...GUSTY WINDS AND PERHAPS SOME MARGINALLY SEVERE HAIL COULD
ACCOMPANY WEAKLY FORCED TSTMS.

..DARROW.. 07/03/2013

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