DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 050751
SWOD48
SPC AC 050750

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0150 AM CST MON NOV 05 2012

VALID 081200Z - 131200Z

...DISCUSSION...
THE ERN TROUGH WILL MOVE OFF THE COAST ENTIRELY BY FRI/D5...WHILE A
LARGE TROUGH AMPLIFIES OVER THE WRN STATES. A BROAD SURFACE LOW IS
FORECAST TO FORM OVER WY AND CO ON D5...WHICH WILL INDUCE SLY WINDS
ACROSS THE PLAINS AND INCREASE LOW LEVEL MOISTURE TRANSPORT NWD. BY
FRIDAY AFTERNOON...BOUNDARY LAYER DEWPOINTS IN THE UPPER 50S F WILL
BE AS FAR N AS ERN KS. HOWEVER...A CAPPING INVERSION IS EXPECTED TO
PRECLUDE WARM SECTOR STORM DEVELOPMENT.

MODELS ARE IN GENERAL AGREEMENT THROUGH SAT/D6...WHEN A BROAD
CYCLONIC JET WILL EXTEND FROM SRN AZ/NM NEWD ACROSS THE PLAINS. IT
APPEARS THERE WILL BE A DISTINCT SHORTWAVE TROUGH THAT WILL AFFECT
THE NRN PLAINS...AND THE GFS AND ECMWF BOTH SHOW A SURFACE LOW
ACROSS WRN/NRN MN BY LATE SATURDAY WITH A COLD FRONT TRAILING SWWD
INTO KS. THEN OVERNIGHT...A SECONDARY LOW IS FORECAST TO FORM INTO
WRN OK BY D7/SUN MORNING.

ALTHOUGH SHEAR WILL BE STRONG ON SAT/D6...INSTABILITY WILL BE WEAK
ALONG THE LENGTH OF THE FRONT AND ESPECIALLY NEAR THE SFC LOW. IN
ADDITION...DUE TO A COOL BOUNDARY LAYER...STORMS ARE LIKELY TO BE
RELEGATED TO THE COLD FRONT WHERE DEEP LAYER SHEAR WILL BE PARALLEL
TO THE BOUNDARY. WITH STRONG SHEAR...A FEW BOWS OR LEWP STRUCTURES
COULD FORM WITH A THREAT OF DAMAGING WINDS. THE ECMWF TROUGH
CONFIGURATION APPEARS MORE FAVORABLE FOR DAMAGING WINDS WITH A
STRONGER SHORTWAVE INTO THE NEB/KS AREA.

DEVELOPMENT MAY CONTINUE SWD ALONG THE FRONT OVERNIGHT WITH A
SLOW-MOVING SQUALL LINE ACROSS KS AND OK. BUT GIVEN ALREADY WEAK
INSTABILITY...AND NOCTURNAL TIMING...IT IS UNCLEAR WHETHER SEVERE
COVERAGE WILL MEET MINIMAL CRITERIA FOR D4-8 TIME FRAME. IT IS
POSSIBLE THAT MANY OF THE ECHOES WILL SIMPLY TRAIN...PRODUCING
MAINLY HEAVY RAIN.

WITH MARGINAL INSTABILITY AND LINEAR FORCING...SUBTLE DIFFERENCES IN
SHORTWAVE TROUGH CONFIGURATION AND TIMING CAN MAKE A LARGE
DIFFERENCE IN THE FINAL SEVERE THREAT. PREDICTABILITY ISSUES WILL
PRECLUDE ANY AREAS AT THIS TIME...BUT THE MOST LIKELY REGION TO
EXPERIENCE SEVERE THUNDERSTORMS WITH DAMAGING WIND WILL BE FROM ERN
NEB INTO KS AND OK.

SOME THREAT MAY ALSO PERSIST INTO SUN/D7 ACROSS ERN TX...AR AND LA.

..JEWELL.. 11/05/2012

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