Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS03 KWNS 010717
SWODY3
SPC AC 010716

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0216 AM CDT MON SEP 01 2014

VALID 031200Z - 041200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS THE UPPER
MISSISSIPPI VALLEY AND NORTHERN PLAINS.

...UPPER MS VALLEY/NRN PLAINS...

WEAK MID-LEVEL HEIGHT RISES ARE EXPECTED ACROSS THE UPPER MS VALLEY
WEDNESDAY...WELL AHEAD OF SHORT-WAVE TROUGH THAT SHOULD PROGRESS
INTO ERN MT BY THE END OF THE PERIOD.  BENEATH WEAK SHORT-WAVE
RIDGING...BOUNDARY LAYER MOISTURE IS EXPECTED TO ADVANCE NWD ACROSS
THE MO VALLEY INTO ERN SD/SRN MN WHERE LOWER 70S SFC DEW POINTS
SHOULD BE IN PLACE BY LATE AFTERNOON.  IN THE ABSENCE OF SIGNIFICANT
LARGE SCALE FORCING...DIABATIC HEATING AND WEAK LOW LEVEL WARM
ADVECTION WILL PROVE INSTRUMENTAL IN CONVECTION THAT EVOLVES ACROSS
THIS REGION.  LATEST NAM/GFS DEVELOP SCT PRECIPITATION WITHIN THE
WARM ADVECTION ZONE ACROSS THE UPPER MS VALLEY.  IT/S NOT CLEAR
WHERE THIS ACTIVITY WILL BE ROOTED AND UPDRAFTS COULD BE ELEVATED
RATHER THAN INGESTING HIGHER QUALITY BOUNDARY LAYER PARCELS.  EVEN
SO...THERE IS SOME CONCERN ROBUST UPDRAFTS WILL EVOLVE AS FORECAST
SOUNDINGS EXHIBIT VEERING WIND PROFILES WITH HEIGHT AND SUFFICIENT
BULK SHEAR FOR SUPERCELLS.  HAVE INTRODUCED 5 PERCENT SEVERE PROBS
TO ACCOUNT FOR THIS UNCERTAINTY.  IF IT BECOMES MORE CLEAR WARM
ADVECTION CONVECTION WILL ROOT INTO HIGH MOISTURE AIRMASS THEN
SEVERE PROBS WILL BE RAISED ACCORDINGLY.

FARTHER WEST...DIFLUENT HIGH-LEVEL FLOW WILL SPREAD ACROSS THE NRN
HIGH PLAINS OF MT INTO THE WRN DAKOTAS BY 04/00Z.  UVV SHOULD
INCREASE ACROSS THIS REGION AFTER DARK AND THE PROSPECT FOR SCT
CONVECTION SHOULD INCREASE ALONG COLD FRONT DURING THE LATTER HALF
OF THE PERIOD.  ONE NEGATIVE FOR ORGANIZED SEVERE ACROSS THIS REGION
IS THE LIMITED LOW-LEVEL MOISTURE.  DESPITE THE ELY BOUNDARY LAYER
FLOW IT APPEARS MOISTURE/INSTABILITY SUFFICIENT FOR STRONG UPDRAFTS
MAY STRUGGLE TO ADVECT INTO ND PRIOR TO FRONTAL PASSAGE.

..DARROW.. 09/01/2014




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