MESO: Mesoscale Discussion 1915

ACUS11 KWNS 260041
SWOMCD
SPC MCD 260041
NDZ000-SDZ000-MTZ000-WYZ000-260245-

MESOSCALE DISCUSSION 1915
NWS STORM PREDICTION CENTER NORMAN OK
0741 PM CDT WED SEP 25 2013

AREAS AFFECTED...NERN WY...WRN SD AND PART OF SERN MT/WRN ND

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 260041Z - 260245Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE THIS
EVENING ACROSS NERN WY AND WRN SD...WITH ADDITIONAL ACTIVITY
DEVELOPING NNEWD THROUGH PART OF SERN MT AND WRN ND. STRONG WIND
GUSTS AND HAIL APPROACHING SEVERE VALUES WILL BE THE PRIMARY
THREATS. GIVEN THE EXPECTED LIMITED COVERAGE FOR STRONGER/SEVERE
STORMS...A WW IS NOT WARRANTED AT THIS TIME.

DISCUSSION...EARLY EVENING SURFACE ANALYSIS SHOWED AN AREA OF LOW
PRESSURE IN SERN WY...WHILE A COLD FRONT EXTENDED SSWWD FROM FAR WRN
ND THROUGH EXTREME SERN MT TO NEAR THE SURFACE LOW AND TRAILED SWWD
INTO NWRN CO. A PRE-FRONTAL WIND SHIFT EXTENDED SWD FROM SWRN ND
THROUGH PERKINS COUNTY AND SRN MEADE COUNTY SD...THEN WSWWD THROUGH
WRN PENNINGTON COUNTY SD TO NRN WESTON COUNTY WY. REGIONAL RADAR
SHOWED A FEW STORMS HAVE DEVELOPED INITIALLY NEAR THE AFOREMENTIONED
SURFACE BOUNDARIES...WITH ONE PRODUCING A SEVERE HAIL EVENT IN
DEADWOOD SD AT 00Z.

THE TRACK OF A MIDLEVEL IMPULSE FROM ERN ID INTO NWRN WY THIS
EVENING WILL RESULT IN THE WY SURFACE LOW MOVING INTO WRN SD...WITH
LITTLE MOVEMENT OF THE SYNOPTIC FRONT OVER WRN ND TO THE LOW IN WRN
SD LATER THIS EVENING. INCREASING DEEP LAYER ASCENT WITH THE
APPROACH OF THE TROUGH...EXIT REGION OF STRENGTHENING SWLY MIDLEVEL
JET...AND INCREASING LOW LEVEL WAA OVER THE WRN DAKOTAS AS A SSELY
LLJ STRENGTHENS FROM THE CENTRAL PLAINS TO DAKOTAS SUGGESTS
ADDITIONAL STORMS WILL BE POSSIBLE. WHILE LAPSE RATES ARE
STEEP...WEAK LOW LEVEL MOISTURE /SURFACE DEWPOINTS IN THE LOWER 40S
F PER 00Z SOUNDING AT RAPID CITY/ WILL LIMIT THE DEGREE OF
DESTABILIZATION AND THE COVERAGE OF STRONGER STORMS. EFFECTIVE BULK
SHEAR IS MORE THAN SUFFICIENT TO SUPPORT STORM ORGANIZATION FOR A
FEW STRONG TO SEVERE STORMS FROM NERN WY INTO WRN SD AND SWRN ND
THIS EVENING.

..PETERS/HART.. 09/26/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BIS...UNR...CYS...BYZ...GGW...

LAT...LON 47400375 47410202 44490255 43830337 43010512 43540548
45080520 46460415 47400375

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