SWODY2
SPC AC 190546
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT THU AUG 19 2010
VALID 201200Z - 211200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL PLAINS
NEWD INTO THE CNTRL GREAT LAKES REGION...
...SYNOPSIS...
COMPLEX UPPER TROUGH CURRENTLY OVER THE INTERMOUNTAIN W WILL
CONTINUE EWD INTO THE PLAINS BY EARLY FRIDAY. NRN PORTION OF THIS
TROUGH WILL EJECT THROUGH THE UPPER GREAT LAKES DURING THE DAY
FRIDAY WHILE SRN PARTS LAG ACROSS THE CNTRL PLAINS THROUGH THE
NIGHT.
...CNTRL PLAINS TO THE GREAT LAKES...
CONFIDENCE IS BELOW AVERAGE ON HOW CONVECTION WILL EVOLVE ON FRIDAY.
SEVERAL CLUSTERS OF THUNDERSTORMS WILL BE ONGOING AT 12Z FRIDAY
FROM THE UPPER MS VALLEY AND ERN PARTS OF THE NRN PLAINS SWD TO
CNTRL NEB/KS.
QUESTIONS REMAIN ON THE QUALITY OF AIR MASS RECOVERY IN WAKE OF THE
MORNING ACTIVITY ACROSS THE UPPER MS VALLEY AS STRONGER LARGE SCALE
HEIGHT FALLS /TIED TO THE ENERGETIC NRN PORTION OF THE UPPER TROUGH/
SPREADS ENE ACROSS THE REGION. IF SUFFICIENT HEATING CAN BE
REALIZED OVER SERN MN...ERN IA AND WI...SHEAR PROFILES WILL BE
CONDUCIVE FOR SUPERCELLS WITH DAMAGING WINDS AND PERHAPS A TORNADO
LATE FRIDAY AFTERNOON/EVENING. THE UNCERTAINTY WILL PRECLUDE
ANYTHING MORE THAN 15 PERCENT SEVERE PROBABILITIES AT THIS TIME.
OVERNIGHT FRIDAY...THUNDERSTORMS WILL MOVE/DEVELOP ENE ALONG/N OF A
RETREATING WARM FRONT TOWARD NRN LOWER/UPPER MI. THE SEVERE THREAT
SHOULD WANE AFTER SUNSET AND WITH EWD EXTENT INTO A MORE STABLE
ENVIRONMENT.
MEANWHILE...COMPARATIVELY STRONGER HEATING WILL TAKE PLACE FROM
SCNTRL IA SWWD INTO ERN KS FRIDAY AFTERNOON...WELL AHEAD OF THE
PRIMARY SYNOPTIC COLD FRONT. AS WEAK ASCENT ASSOCIATED WITH THE SRN
PORTION OF THE UPPER TROUGH SKIRTS THE REGION...THUNDERSTORMS WILL
FORM ALONG PRE-FRONTAL BOUNDARIES. MLCAPES TO 2500 J/KG...STEEP LOW
AND MID-LEVEL LAPSE RATES AND AT LEAST 30-35 KTS OF WLY MID-LEVEL
FLOW WILL YIELD STRONG/SEVERE MULTICELL STORMS CAPABLE OF PRIMARILY
DAMAGING WIND GUSTS. THE SEVERE THREAT SHOULD DIMINISH AFTER DARK
AS INSTABILITY DECREASES. HOWEVER...A NON-SEVERE NOCTURNAL
THUNDERSTORM CLUSTER WILL PROBABLY EVOLVE/ CONTINUE THROUGH 12Z
ACROSS PARTS OF NERN OK AND THE MO OZARKS.
...ERN ND AND FAR NW MN...
ALTHOUGH THE PRIMARY PORTION OF THE AFOREMENTIONED UPPER TROUGH WILL
MOVE ESSENTIALLY E OF THE REGION BY EARLY FRIDAY...MODELS HAVE BEEN
SIGNALING DEVELOPMENT OF A THUNDERSTORM BAND OVER SRN MANITOBA BY
LATE FRIDAY AFTERNOON. THESE STORMS WILL LIKELY FORM ALONG SRN
PERIPHERY OF A WEAK IMPULSE MOVING ACROSS THE CANADIAN PRAIRIES AND
A SWD MOVING COLD FRONT. RESIDUAL SURFACE DEW POINTS IN THE
LOWER-MID 60S BENEATH RELATIVELY COOL MID-LEVEL TEMPERATURES WILL
BOOST MLCAPES TO AROUND 1500 J/KG. FAVORABLE BUOYANCY COUPLED WITH
ROUGHLY 30-35 KTS OF EFFECTIVE WESTERLY SHEAR...A COUPLE STORMS MAY
YIELD LARGE HAIL AND/OR DAMAGING WINDS AS THEY SETTLE INTO ERN ND
AND FAR NW MN FRIDAY EVENING.
..RACY.. 08/19/2010
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