Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 221728
SWODY2
SPC AC 221727

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1227 PM CDT FRI AUG 22 2014

VALID 231200Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN SD...SERN ND AND WRN
MN...

...SUMMARY...
SCATTERED THUNDERSTORMS CAN BE EXPECTED ACROSS PARTS OF THE NORTHERN
PLAINS AND THE UPPER MISSISSIPPI VALLEY ON SATURDAY. THE STRONGEST
STORMS MAY PRODUCE SOME HAIL...GUSTY WINDS...AND A TORNADO THREAT.

...SYNOPSIS...
A SHORTWAVE TROUGH MOVING INTO THE NRN INTERMOUNTAIN WEST...GREAT
BASIN AND NRN ROCKIES TODAY WILL SHIFT EWD THEN NEWD DURING DAY 2
WITH SOME DEEPENING OF THIS SYSTEM AS IT TAKES ON A NEGATIVE TILT
TRACKING TOWARD THE NRN PLAINS.  A SPEED MAX ROUNDING THE BASE OF
THE WRN TROUGH TODAY MAY PHASE WITH A SHORTWAVE TROUGH...CURRENTLY
MOVING INTO THE FOUR CORNERS REGION...AS THESE FEATURES TRACK NNEWD
ACROSS THE DAKOTAS SATURDAY AFTERNOON AND THROUGH THE NRN RED RIVER
VALLEY TO SOUTH CENTRAL CANADA SATURDAY NIGHT.

CONCURRENT WITH THIS EVOLUTION...AN AREA OF LOW PRESSURE WILL TRACK
FROM NWRN KS/SWRN NEB AT 23/12Z THROUGH THE NRN PLAINS TO IN
VICINITY OF THE NERN ND/MANITOBA BORDER.  A WARM FRONT APPROACHING
THE MID MO RIVER VALLEY EARLY SATURDAY MORNING WILL CONTINUE TO
ADVANCE POLEWARD AND SHOULD EXTEND FROM CENTRAL-ERN SD INTO
SWRN-SOUTH CENTRAL MN SATURDAY AFTERNOON.  STRONG LOW-LEVEL WAA
EXPECTED THROUGH DAY 2 ALONG AND NORTH OF THE WARM FRONT AND UPWARD
VERTICAL MOTION ATTENDANT TO MID-LEVEL IMPULSES TRACKING NWD THROUGH
THE NRN PLAINS WILL SUPPORT AN EXTENDED PERIOD OF SHOWERS/TSTMS N
AND NW OF THE WARM SECTOR.

...PORTIONS OF THE NRN PLAINS...
GIVEN SOME UNCERTAINTY IN THE MOTION OF THE SURFACE LOW THROUGH SD
SATURDAY AFTERNOON AND ITS AFFECT ON THE PLACEMENT OF THE WARM
SECTOR THROUGH PEAK HEATING...THERE IS POTENTIAL THAT MORE OF ERN SD
WILL NEED TO BE IN THE SLIGHT RISK.  DESPITE SOME DIFFERENCES IN THE
LOCATION OF THE SURFACE LOW BY 24/00Z /00Z ECMWF BEING THE FARTHEST
SOUTH ACROSS SOUTH CENTRAL SD/...MODELS TEND TO AGREE WITH NEW
CONVECTIVE DEVELOPMENT IN ERN SD NEAR THE SRN PERIPHERY OF THE
ONGOING AFOREMENTIONED AREA OF WAA SHOWERS/TSTMS.  AND...NEW
DEVELOPMENT MAY OCCUR SWD INTO NORTH CENTRAL-NERN NEB LATE SATURDAY
AFTERNOON...ESPECIALLY AS A COLD FRONT ADVANCES EWD TOWARD THIS
REGION.  THESE FACTORS COMBINED WITH THE JUXTAPOSITION OF MODERATE
INSTABILITY WITHIN THE WARM SECTOR AND EFFECTIVE BULK SHEAR OF 35-40
KT SUGGEST THE SWD EXPANSION OF THE SLIGHT RISK IS WARRANTED TO
INCLUDE...AT LEAST...MORE OF EAST CENTRAL SD.  GIVEN FAVORABLE DEEP
LAYER SHEAR AND LOW-LEVEL SHEAR FOR ORGANIZED STORMS...INCLUDING
SUPERCELLS...ALL SEVERE HAZARDS WILL BE POSSIBLE.  THE TRACK OF THE
SHORTWAVE TROUGH AND SURFACE LOW INTO ERN ND SATURDAY NIGHT SUGGESTS
STRONG-SEVERE STORMS WILL MOVE NNE TOWARD THE NRN RED RIVER VALLEY
AND WEST-CENTRAL/NWRN MN.

..PETERS.. 08/22/2014




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