MESO: Mesoscale Discussion 1694

ACUS11 KWNS 222217
SWOMCD
SPC MCD 222217
NDZ000-SDZ000-MTZ000-WYZ000-222345-

MESOSCALE DISCUSSION 1694
NWS STORM PREDICTION CENTER NORMAN OK
0517 PM CDT FRI JUL 22 2011

AREAS AFFECTED...ERN MT...SW ND...WRN SD

CONCERNING...TORNADO WATCH 671...

VALID 222217Z - 222345Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 671 CONTINUES.

THE SEVERE THREAT ACROSS THE CNTRL PART OF WW 671 WILL LIKELY SPREAD
ESEWD LATE THIS AFTERNOON. AN MCS WILL LIKELY ORGANIZE THIS EVENING
WITH THE ACTIVITY MOVING SEWD INTO WRN ND AND NW SD. IN
ADDITION...ISOLATED THUNDERSTORMS ARE INITIATING WELL TO THE EAST OF
THE LINE IN SW ND WHERE A WW WILL LIKELY BE NEEDED. LARGE
HAIL...WIND DAMAGE AND POSSIBLY A FEW TORNADOES WILL LIKELY EXIST
WITH THE MORE INTENSE CELLS.

A BROKEN LINE OF STRONG THUNDERSTORMS IS ONGOING ON THE WRN EDGE OF
MODERATE INSTABILITY WHERE MLCAPE VALUES ARE ESTIMATED IN THE 2000
TO 3000 J/KG RANGE. THE STORMS ARE BEING SUPPORTED BY LARGE-SCALE
ASCENT ASSOCIATED WITH A SHORTWAVE TROUGH OVER CNTRL MT EVIDENT ON
WATER VAPOR IMAGERY. A WELL-DEFINED 50 TO 60 KT MID-LEVEL JET ACROSS
SRN MT ASSOCIATED WITH THE SHORTWAVE IS CREATING STRONG DEEP LAYER
SHEAR PROFILES WHICH COMBINED WITH STEEP MID-LEVEL LAPSE RATES WILL
BE FAVORABLE FOR SUPERCELLS AND LARGE HAIL. DISCRETE CELLS ARE ALSO
INITIATING IN SW ND WELL AHEAD OF THE LINE WHERE SFC WINDS ARE
BACKED. AS LOW-LEVEL FLOW INCREASES EARLY THIS EVENING...THE THREAT
FOR TORNADOES AND LARGE HAIL SHOULD INCREASE WITH SUPERCELLS THAT
INITIATE AHEAD OF THE LINE WHERE SFC DEWPOINTS IN WRN AND SRN ND ARE
IN THE MID TO UPPER 60S F. AN ISOLATED TORNADO THREAT WILL ALSO
EXIST WITH THE MORE DOMINANT CELLS EMBEDDED IN THE LINE. IF A COLD
POOL CAN ORGANIZE...THEN A WIND DAMAGE THREAT WILL ALSO EXIST AS THE
LINE MOVES INTO WRN ND AND NW SD LATER THIS EVENING.

..BROYLES.. 07/22/2011

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

ATTN...WFO...ABR...BIS...UNR...BYZ...GGW...TFX...

LAT...LON 47100093 48090306 48490576 48530693 48220773 46860879
45730942 45100895 44980748 44930637 44870459 44640281
44930179 45590130 46500082 47100093

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