MESO: Mesoscale Discussion 0567

ACUS11 KWNS 252219
SWOMCD
SPC MCD 252218
INZ000-ILZ000-WIZ000-IAZ000-MOZ000-252345-

MESOSCALE DISCUSSION 0567
NWS STORM PREDICTION CENTER NORMAN OK
0518 PM CDT SAT APR 25 2009

AREAS AFFECTED...NERN MO...ERN IA...NRN IL...SRN WI...EXTREME NERN
IND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 252218Z - 252345Z

THUNDERSTORM COVERAGE WILL CONTINUE TO INCREASE ACROSS NERN MO...ERN
IA...NRN IL...SRN WI...AND EXTREME NERN IND THROUGH THE EVENING. A
WATCH DOES NOT APPEAR NECESSARY AT THIS TIME...BUT CONVECTIVE TRENDS
WILL CONTINUE TO BE MONITORED.

AT 21Z...A SLOW MOVING COLD FRONT WAS OBSERVED EXTENDING NEWD FROM
THE KANSAS CITY METRO AREA TOWARD NRN IL AND EWD INTO SRN MI. A
COOL/STABLE BOUNDARY LAYER AIRMASS EXISTS NORTH OF THE FRONT...WHILE
TEMPERATURES HAVE WARMED INTO THE 70S AND 80S TO ITS SOUTH...AND
SURFACE DEWPOINTS RESIDE IN THE LOW 60S...CONTRIBUTING TOWARD MLCAPE
VALUES AROUND 1000-1500 J/KG. RRQ OF 160 KT ULJ RESIDES OVER THE
REGION...AND SEVERAL WEAK UPR LVL IMPULSES ARE EMANATING OUT OF
CNTRL/SRN PLAINS. THESE FEATURES ARE PROVIDING FAVORABLE LARGE SCALE
ASCENT FOR DESTABILIZATION...WHILE MESOSCALE ASCENT ALONG AND N OF
STATIONARY FRONT IS FORECAST TO INCREASE DURING THE NIGHT AS SWLY
LLJ STRENGTHENS TO 30-50 KT. STORMS WILL CONTINUE TO INCREASE IN
COVERAGE AS A RESULT...INCLUDING LOCATIONS N OF THE SURFACE FRONT AS
MUCAPE INCREASES TO 1000 J/KG.

FORECAST SOUNDINGS AND VWP DATA INDICATE SHEAR VALUES WILL FAVOR
MAINLY MULTICELL STORM TYPES DURING THE NEXT FEW HRS...WITH A
GRADUAL INCREASE IN LOW LVL SHEAR LIKELY AS THE LLJ STRENGTHENS
DURING THE NIGHT. STORMS FORMING IN THIS ENVIRONMENT MAY BE CAPABLE
OF PRODUCING MARGINALLY SVR HAIL AND PERHAPS AN ISOLATED DAMAGING
WIND GUST...BUT THE THREAT DOES NOT APPEAR TO WARRANT A WATCH AT
THIS TIME. HOWEVER...CONVECTIVE TRENDS WILL BE MONITORED FOR AN
INCREASE IN STORM ORGANIZATION.

..GARNER.. 04/25/2009

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

ATTN...WFO...LOT...ILX...MKX...LSX...DVN...ARX...

LAT...LON 42638737 42128711 41318751 39479042 39709179 41089205
42379179 43099040 43198878 43058821 42638737

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