DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 040841
SWOD48
SPC AC 040840

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0340 AM CDT THU APR 04 2013

VALID 071200Z - 121200Z

...DISCUSSION...
...SUNDAY/D4 - NERN OK INTO THE LOWER MO VALLEY...
MODELS ARE IN GOOD AGREEMENT IN MOVING A LOW AMPLITUDE SHORTWAVE
TROUGH FROM THE ROCKIES EWD ACROSS THE CNTRL PLAINS DURING THE DAY
AND TO THE MS RIVER BY 12Z MON. THIS PATTERN WILL ALLOW LOW LEVEL
MOISTURE TO INCREASE ON SLY FLOW AROUND THE WRN ATLANTIC
ANTICYCLONE...WITH MID TO UPPER 50S F DEWPOINTS INTO KS AND MO BY
00Z. ISENTROPIC LIFT N OF THE WARM FRONT WILL BE ENHANCED BY THE
SHORTWAVE TROUGH...AND SCATTERED THUNDERSTORMS ARE EXPECTED TO LIFT
NEWD ACROSS ERN KS...MO...IA...AND IL DURING THE EVENING AND
OVERNIGHT. COOL TEMPERATURE PROFILES ALOFT AND ADEQUATE CLOUD
BEARING SHEAR MAY SUPPORT SOME MARGINALLY SEVERE HAIL.

...MONDAY/D5 - CNTRL AND WRN KS...NWRN OK...
MODELS INDICATE THE WRN TROUGH AMPLIFYING ON MON WITH A 90 KT
MIDLEVEL SPEED MAX DIGGING SEWD ACROSS CA AND NOSING INTO THE SRN
HIGH PLAINS BY TUE MORNING WITH STRONG HEIGHT FALLS. AT THE
SURFACE...LOW PRESSURE IS FORECAST TO DEEPEN SOMEWHERE NEAR THE
TX/OK PANHANDLE AREA...WITH A WARM FRONT EXTENDING EWD ACROSS KS AND
INTO MO. A DRYLINE SHOULD EXTEND SWD NEAR THE TX/WRN OK BORDER AS
WELL. LOWER 60S F BOUNDARY LAYER DEWPOINTS SHOULD EXIST ACROSS MUCH
OF THE WARM SECTOR...WITH MID 60S F TO THE RED RIVER. WITH COOL
TEMPERATURES ALOFT...THIS WILL RESULT IN MODERATE INSTABILITY
LEVELS.

THE MOST LIKELY AREA FOR CONCENTRATED SEVERE STORMS APPEARS TO BE
OVER SWRN KS...WHERE COOLER AIR ALOFT WILL RESULT IN THE LEAST
AMOUNT OF CAPPING POTENTIAL AND WHERE SFC CONVERGENCE WILL BE
MAXIMIZED ALONG WITH HEATING. WIND PROFILES WILL BE DECIDEDLY
SUPERCELLULAR WITH EXTREME HAIL POSSIBLE AS WELL AS A FEW TORNADOES.
DURING THE EVENING...WARM ADVECTION WITH THE NOCTURNAL LOW LEVEL JET
WILL BE MAXIMIZED AND MAY INCREASE STORM COVERAGE. THE MAIN MODEL
DIFFERENCE IS HOW THE EVENING STORMS MAY BE FORCED. THE GFS
INDICATES A COLD FRONT SURGING SWD. IF THIS OCCURS...INITIAL
SUPERCELLS COULD EVENTUALLY MERGE INTO AN MCS. THE ECMWF SOLUTION IS
MORE SUPPORTIVE OF CONTINUED SUPERCELLS AFTER DARK WITH THE BOUNDARY
REMAINING STATIONARY ACROSS NRN KS.

MORE ISOLATED STORMS ARE LIKELY SWD INTO WRN OK/TX ALONG THE
DRYLINE...BUT THIS THREAT AREA COULD BE CONFINED TO A NARROW ZONE AS
CAPPING INCREASES TO THE E. RECENT HEAVY RAINS AND DECREASED SURFACE
ALBEDO MAY PROVIDE A FEEDBACK MECHANISM FOR COOLER TEMPERATURES AS
WELL.

...TUESDAY/D6 TO THURSDAY/D8 - ERN OK/ARKLATEX INTO THE MIDDLE AND
LOWER MS VALLEY...
AFOREMENTIONED COLD FRONT DEPICTED BY GFS IS FORECAST TO SURGE SWD
AND WILL BECOME A PRIMARY FOCUS FOR CONVECTION FROM NRN IL INTO MO
AND OK...LINKING WITH THE DRYLINE OVER N CNTRL TX. BY
TUESDAY...SUBSTANTIAL BOUNDARY LAYER MOISTURE WILL BE IN PLACE WITH
UPPER 60S F DEWPOINTS AHEAD OF THE FRONT.

MEANWHILE...THE ECMWF SOLUTION KEEPS THE SYNOPTIC FRONT STATIONARY
ACROSS SRN NEB INTO NRN IL/IND DURING THE DAY ON TUE...WITH THE
DRYLINE FROM CNTRL KS INTO OK AND CNTRL TX. THIS MODEL ALSO
INDICATES SUBSTANTIAL MOISTURE AND INSTABILITY POTENTIAL FROM
KS/OK/TX INTO THE LOWER MS VALLEY.

GIVEN THESE MODEL DIFFERENCES...PREDICTABILITY IS TOO LOW FOR AN
AREA ON TUE/D6...ALTHOUGH THERE IS THE POTENTIAL FOR SIGNIFICANT
SEVERE INCLUDING TORNADOES. THE THREAT SHOULD PERSIST INTO WED/D7
ACROSS THE LOWER MS VALLEY. AREAS ARE LIKELY TO BE INTRODUCED AS
PREDICTABILITY INCREASES IN SUBSEQUENT OUTLOOKS.

..JEWELL.. 04/04/2013

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