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044
ACUS02 KWNS 180547
SWODY2
SPC AC 180546

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT THU SEP 18 2014

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
THUNDERSTORM DEVELOPMENT IS EXPECTED TO OCCUR FROM THE INTERMOUNTAIN
WEST EASTWARD INTO THE GREAT PLAINS AND NORTHEASTWARD TO THE WESTERN
GREAT LAKES REGION. SOME MARGINALLY SEVERE THUNDERSTORMS WITH HAIL
AND STRONG WINDS MAY OCCUR ACROSS PARTS OF THE UPPER MISSISSIPPI
VALLEY. OTHER STORMS MAY DEVELOP IN PARTS OF THE GULF COAST STATES.

...UPPER MS VALLEY...
AN UPPER-LEVEL RIDGE IN THE NRN PLAINS WILL MOVE EWD INTO THE UPPER
MS VALLEY AND FLATTEN ON FRIDAY AS A SHORTWAVE TROUGH MOVES INTO THE
NRN PLAINS. AT THE SFC...A COLD FRONT IS FORECAST TO ADVANCE SEWD
ACROSS THE NRN PLAINS FRIDAY. AHEAD OF THE FRONT...A CORRIDOR OF
LOW-LEVEL MOISTURE SHOULD BE LOCATED ACROSS IA...SRN MN AND ERN SD
FRIDAY ALONG WHICH MODERATE INSTABILITY SHOULD DEVELOP BY AFTERNOON.
WARM AIR ALOFT AND A CAPPING INVERSION SHOULD PREVENT CONVECTIVE
INITIATION UNTIL EARLY TO MID EVENING WHEN ISOLATED THUNDERSTORM
DEVELOPMENT WILL BE POSSIBLE AHEAD OF THE FRONT.

NAM FORECAST SOUNDINGS AT 03Z/SATURDAY FOR SRN MN SUGGEST THE CAP
MAY WEAKEN ENOUGH BY THAT TIME FOR CONVECTIVE INITIATION BUT A SFC
INVERSION MAY STILL BE PRESENT. AS A RESULT...ANY CELL THAT CAN
DEVELOP SHOULD BE ELEVATED IN NATURE.  THE FORECAST SOUNDINGS ALSO
SHOW MODERATE INSTABILITY...40 KT OF EFFECTIVE SHEAR AND 850 TO 500
MB LAPSE RATES AROUND 7.5 C/KM. IF A FEW UPDRAFTS CAN PERSIST AS
LARGE-SCALE ASCENT INCREASES DUE TO THE APPROACHING SHORTWAVE
TROUGH...THEN AN ISOLATED HAIL THREAT WOULD BE POSSIBLE FRIDAY
EVENING.

..BROYLES.. 09/18/2014





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