MESO: Mesoscale Discussion 1754

ACUS11 KWNS 292157
SWOMCD
SPC MCD 292157
NDZ000-SDZ000-MTZ000-WYZ000-292330-

MESOSCALE DISCUSSION 1754
NWS STORM PREDICTION CENTER NORMAN OK
0457 PM CDT SUN AUG 29 2010

AREAS AFFECTED...S-CNTRL/SERN MT...SWRN ND

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 292157Z - 292330Z

AN ISOLATED SEVERE THREAT CONSISTING PRIMARILY OF HAIL SHOULD
DEVELOP WITHIN A LOWER-LEVEL BAROCLINIC ZONE ACROSS SRN MT INTO THE
WRN DAKOTAS. A SEVERE TSTM WATCH IS NOT ANTICIPATED ATTM...BUT
OBSERVATIONAL TRENDS WILL CONTINUE TO BE MONITORED.

21Z SUBJECTIVE SURFACE ANALYSIS PLACED A PAIR OF CYCLONES ACROSS
SWRN MT /S OF BZN/ AND OVER CNTRL SD /INVOF PIR AND MBG/. A
QUASI-STATIONARY FRONT WAS DRAPED BETWEEN THESE TWO FEATURES OVER
WRN SD AND FAR NRN WY. A RECENT INCREASE IN TSTM ACTIVITY HAS
OCCURRED ACROSS SWRN/S-CNTRL MT LIKELY IN ASSOCIATION WITH A WEAK
UPPER-LEVEL IMPULSE AND SPEED MAX EJECTING NEWD DOWNSTREAM OF THE
LARGE-SCALE WRN CONUS TROUGH. PERSISTENT LOWER-LEVEL WARM ADVECTION
ATOP WEAK UPSLOPE FLOW SHOULD PROVE SUFFICIENT FOR ISOLATED TO
SCATTERED TSTMS CONTINUING TO SHIFT E/NEWD THROUGH MUCH OF THE
EVENING. THIS SCENARIO IS SUPPORTED BY RECENT HRRR RUNS AND 18Z
GFS/NAM GUIDANCE. EFFECTIVE SHEAR WILL REMAIN STRONG /AROUND 40-50
KT/...AND WITH THE BAROCLINIC ZONE LYING ON THE NRN PERIPHERY OF
STEEPER MID-LEVEL LAPSE RATES...LARGE HAIL WOULD LIKELY BE THE
PRIMARY SEVERE THREAT. HOWEVER...THIS THREAT SHOULD REMAIN WITHIN A
RELATIVELY NARROW WSW TO ENE CORRIDOR ACROSS SRN MT INTO SWRN
ND...SOUTH OF THE PERSISTENT STRATUS DECK HOLDING OVER MUCH OF NERN
MT/NWRN ND.

..GRAMS.. 08/29/2010

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

ATTN...WFO...BIS...UNR...BYZ...GGW...RIW...

LAT...LON 45430979 46060937 46210789 46500593 46590578 47100421
47120311 46570282 45990320 45360410 45010545 44920673
44920809 45430979

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