DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 180552
SWODY1
SPC AC 180550

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT SUN AUG 18 2013

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN
PLAINS...

...NRN PLAINS...
A SHORTWAVE TROUGH WILL MOVE QUICKLY EWD FROM THE NRN ROCKIES INTO
THE NRN PLAINS TODAY. AT THE SFC...A COLD FRONT WILL ADVANCE SEWD
ACROSS THE NRN PLAINS AND SHOULD BE POSITIONED FROM NRN MN SWWD INTO
ERN ND AND NWRN SD BY LATE AFTERNOON. SFC HEATING AND ENHANCED
LOW-LEVEL CONVERGENCE ALONG THE COLD FRONT...SHOULD ALLOW STORMS TO
INITIATE DURING THE LATE AFTERNOON. THE MODELS SUGGEST THAT SEVERAL
STORM CLUSTERS WILL ORGANIZE AND PERSIST INTO THE EARLY TO MID
EVENING AS THE FRONT MOVES SEWD ACROSS THE REGION.

NAM FORECAST SOUNDINGS ALONG THE FRONT FOR JAMESTOWN AND BISMARCK ND
AT 00Z/MON SHOW SFC DEWPOINTS NEAR 60 F WITH MUCAPE VALUES AROUND
2000 J/KG. IN ADDITION...DEEP LAYER SHEAR IS FORECAST TO BE IN THE
35 TO 45 KT RANGE WITH LARGE TEMP-DEWPOINT SPREADS SUGGESTING
HIGH-BASED SUPERCELLS WILL BE POSSIBLE. IF CELLS CAN OBTAIN
ROTATION...THEN A THREAT FOR LARGE HAIL SHOULD DEVELOP IN THE LATE
AFTERNOON AND EARLY EVENING. VERY STEEP LOW-LEVEL LAPSE RATES SHOULD
HELP ACCELERATE DOWNDRAFTS SPEEDS RESULTING IN A WIND DAMAGE THREAT
AS WELL.

...CNTRL HIGH PLAINS...
THE SRN END OF A SHORTWAVE TROUGH IS FORECAST TO MOVE EWD ACROSS THE
CNTRL HIGH PLAINS TODAY. AT THE SFC...A LEE TROUGH WILL SHARPEN FROM
SWRN SD SWD INTO NERN CO ALONG WHICH THUNDERSTORMS ARE FORECAST TO
DEVELOP LATE THIS AFTERNOON. MODERATE INSTABILITY...SOME DIRECTIONAL
SHEAR IN THE LOW TO MID-LEVELS AND LARGE TEMP-DEWPOINT SPREADS
SHOULD BE ENOUGH FOR MARGINALLY SEVERE WIND GUSTS WITH THE STRONGER
HIGH-BASED STORMS. HAIL COULD ALSO OCCUR DUE TO THE INSTABILITY AND
STEEP MID-LEVEL LAPSE RATES.

...CNTRL GULF COAST...
AN UPPER-LEVEL IMPULSE WILL MOVE NWD TOWARD THE CNTRL GULF COAST
TODAY. AHEAD OF THE SYSTEM...SFC DEWPOINTS IN THE LOWER TO MID 70S F
ACROSS THE CNTRL GULF COAST SHOULD CONTRIBUTE TO MODERATE
DESTABILIZATION THIS AFTERNOON. AS THE SYSTEM APPROACHES AND
LARGE-SCALE ASCENT INCREASES...THUNDERSTORM COVERAGE SHOULD EXPAND
NWD INTO THE CNTRL GULF COAST STATES THIS AFTERNOON. THE HIGH SFC
DEWPOINTS AND SUFFICIENT LOW-LEVEL SHEAR COULD BE ENOUGH FOR A
MARGINAL TORNADO THREAT. A FEW STRONG WIND GUSTS WILL ALSO BE
POSSIBLE.

..BROYLES.. 08/18/2013

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.