DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 010733
SWOD48
SPC AC 010732

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0232 AM CDT TUE OCT 01 2013

VALID 041200Z - 091200Z

...DISCUSSION...
...FRIDAY D4: NEB...IA...MN...WI...
MODELS HAVE COME INTO BETTER ALIGNMENT AND CONFIDENCE IS HIGH FOR A
SEVERE WEATHER EPISODE ON FRI/D4 ANYWHERE FROM FAR ERN NEB INTO
IA...SRN MN...AND SWRN WI.

THE WRN TROUGH IS FORECAST TO MOVE INTO THE PLAINS ON
FRIDAY/D4...WITH A RAPIDLY DEEPENING SURFACE LOW NEAR THE NEB/IA
BORDER FRIDAY LATE AFTERNOON...CONTINUING NEWD INTO MN OVERNIGHT.

BOUNDARY LAYER DEWPOINTS ON THE ORDER OF 65-68 F WILL ALREADY BE IN
PLACE ACROSS THE WARM SECTOR...E OF THE DEVELOPING COLD FRONT
TRAILING S FROM THE SURFACE LOW...AND S OF A WARM/STATIONARY FRONT
WHICH WILL BE ACROSS SRN MN INTO CNTRL WI.

DUE TO COOLING ALOFT WITH THIS STRONG SYSTEM...MIDLEVEL LAPSE RATES
WILL BE STEEP FOR THIS TIME OF YEAR...PERHAPS NEAR 8.0 C/KM...ATOP A
MOIST BOUNDARY LAYER RESULTING IN CLASSIC LOADED GUN PROFILES.
HODOGRAPHS WILL BE VERY LARGE NEAR THE SURFACE LOW TRACK...AND WILL
FAVOR SUPERCELLS PRODUCING TORNADOES...SOME POSSIBLY STRONG...AND
VERY LARGE HAIL. A FASTER MOVING FRONT OR EARLIER INITIATION COULD
LEAD TO MORE OF A LINEAR MODE WITH DAMAGING WINDS...BUT DETAILS SUCH
AS THESE HAVE LOW PREDICTABILITY THIS FAR OUT.

...FRIDAY D4: ERN KS...OK...WRN MO...
THE COLD FRONT IS FORECAST TO RAPIDLY SURGE SEWD ACROSS THE REGION
WITH THE MORE FAVORABLE FORCING FARTHER N. STILL...SCATTERED TO
NUMEROUS STORMS IN THE FORM OF A SQUALL LINE IS EXPECTED ALONG THE
COLD FRONT. INTERROGATION OF FORECAST SOUNDINGS SUGGEST CAPPING WILL
BE A FACTOR AWAY FROM THE FRONT. AS A RESULT...ANY CHANCE OF
SUPERCELLS WILL LIKELY BE IN A VERY SHORT TIME WINDOW UNTIL THE
FRONT UNDERCUTS THEM...ACROSS WRN AREAS WHERE HEATING IS STRONGEST.
LOCALLY DAMAGING WINDS AND PERHAPS MARGINALLY SEVERE HAIL WILL OCCUR
WITH THE SQUALL LINE.

...SATURDAY D5: MI INTO THE LOWER OH/MID MS VALLEY...
THE COLD FRONT IS EXPECTED TO BECOME OCCLUDED INTO SAT/D5 AS THE LOW
ROTATES NWD ACROSS THE UPPER MS VALLEY. STRONG FLOW NEARLY PARALLEL
TO THE FRONT AND MARGINAL INSTABILITY WILL RESULT IN SCATTERED
STRONG STORMS...SOME OF WHICH COULD BE SEVERE WITH DAMAGING WINDS OR
HAIL...BUT THE THREAT IS NOT EXPECTED TO BE HIGH END.

..JEWELL.. 10/01/2013

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