ACUS01 KWNS 240100
SWODY1
SPC AC 240058
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 PM CDT SAT JUN 23 2007
VALID 240100Z - 241200Z
..THERE IS A SLGT RISK OF SVR TSTMS NRN PORTIONS ND/MN...
..SYNOPSIS...
SYNOPTIC PATTERN REMAINS DOMINATED BY RIDGING FROM AZ NEWD ACROSS
SRN/ERN CANADIAN PRAIRIE PROVINCES...WITH DOWNSTREAM TROUGH ACROSS
CANADIAN MARITIMES. PERSISTENT MID/UPPER LEVEL CYCLONIC SHEAR ZONE
AND EMBEDDED VORTICITY MAXIMA OVER SRN PLAINS HAS PHASED WITH
SLOW-MOVING SHORTWAVE TROUGH LOCATED ACROSS MO/IL. WEAK SHORTWAVE
TROUGH -- EVIDENT ATTM IN MOISTURE CHANNEL IMAGERY OVER EXTREME NERN
MT AND SERN SK -- IS EXPECTED TO TURN EWD THROUGH LARGER SCALE RIDGE
POSITION OVERNIGHT...THEN ESEWD ACROSS NRN ND...SERN MB AND WRN
PORTIONS NWRN ONT NEAR END OF PERIOD.
AT SFC...LOW IS ANALYZED OVER SERN SK...WITH COLD FRONT SSWWD ACROSS
SERN MT. COLD FRONT SHOULD MOVE EWD ACROSS PORTIONS ND AND NWRN SD
OVERNIGHT...DECELERATING AND PERHAPS STALLING ON SRN END IN RESPONSE
TO SECOND SFC CYCLONE CONSOLIDATING INVOF NERN WY/NWRN SD. OLD
OUTFLOW BOUNDARY EXTENDS ESE OF SERN SK LOW AND IS ACTING AS
PSEUDO-WARM FRONT. THIS BOUNDARY -- MAINLY N OF CANADIAN BORDER NOW
EXCEPT INVOF NERN CORNER OF ND -- SHOULD CONTINUE LIFTING NWD OVER
EXTREME SRN MB.
..NRN PLAINS TO BOUNDARY WATERS AND WRN LS REGIONS...
ISOLATED SVR TSTMS ARE EVIDENT NW DLH. ACTIVITY IS MOVING SWD ALONG
DIFFUSE/QUASISTATIONARY SFC THERMAL BOUNDARY THAT IS LOCATED S OF
MAIN SYNOPTIC WARM FRONT IN CANADA...AND ADDITIONAL CONVECTION MAY
FORM OVER NERN MN WITH FURTHER POTENTIAL FOR LARGE HAIL AND STG-SVR
GUSTS.
ANOTHER SVR EPISODE OF BROADER COVERAGE IS POSSIBLE LATE THIS
EVENING AND OVERNIGHT...FROM NERN ND ESEWD ACROSS PORTIONS NRN MN.
THIS IS RELATED IN PART TO LARGE/PROMINENT/HEAVY-PRECIP SUPERCELL
NOW BEING OBSERVED OVER PORTIONS SWRN MB. ACTIVITY IS OCCURRING ON
NRN EDGE OF STRONGEST CAPPING PER MODIFIED RAOBS AND RUC
SOUNDINGS...AND SHOULD CONTINUE TO MOVE ESEWD WHILE INTERACTING WITH
OUTFLOW/WARM FRONTAL BOUNDARY. THIS STORM -- ALONG WITH ADDITIONAL
CONVECTION TO ITS N -- MAY EVOLVE UPSCALE INTO MCS WITH DAMAGING
WIND AND PERHAPS DERECHO POTENTIAL...WHILE CONTINUING ITS THREAT OF
LARGE HAIL AND TORNADOES AS LONG AS SUPERCELL STRUCTURES ARE
MAINTAINED. MAIN UNCERTAINTY ATTM IS HOW MUCH OF THIS THREAT WILL
EXTEND S OF CANADIAN BORDER.
ALTHOUGH MOST MODELS CONTINUE TO PROG BULK OF CONVECTION ACROSS SERN
MB EWD OVER ONT THROUGH REMAINDER PERIOD...PRIND AIR MASS ACROSS
OUTLOOK AREA WILL REMAIN FAVORABLE FOR SVR...THEREFORE CATEGORICAL
OUTLOOK WILL BE MAINTAINED AND WIND PROBABILITIES BOOSTED BY ONE
FACTOR IN SMALL AREA NEAR BORDER. CORRIDOR OF VERY
RICH/EVAPOTRANSPIRATIVELY ENHANCED LOW LEVEL MOISTURE -- E.G. SFC
DEW POINTS 70-80 DEG F -- IS ANALYZED NEAR BOUNDARY...ACROSS SERN
MB...NERN ND AND NWRN MN. ASSOCIATED STG TO EXTREME INSTABILITY
SUPPORTS MUCAPES 3000-5000 J/KG...IN SETTING OF ENLARGED LOW LEVEL
HODOGRAPHS ALONG AND N OF BOUNDARY.
ADDITIONAL DEVELOPMENT ALSO IS POSSIBLE SWWD ALONG COLD FRONT...BUT
BECAUSE OF STRONG CINH...THREAT IS MORE CONDITIONAL AND MRGL SVR
PROBABILITIES ARE MAINTAINED.
..SRN HIGH PLAINS AND OH VALLEY REGION...
COMBINED AREA OF LARGE SCALE ASCENT ASSOCIATED WITH AFOREMENTIONED
MID-UPPER PERTURBATIONS...IN TANDEM WITH RICH LOW LEVEL
MOISTURE...WEAK CINH AND DIURNAL HEATING...HAS CONTRIBUTED TO
SCATTERED TSTMS IN CLUSTERS ACROSS THESE AREAS THIS AFTERNOON. A
FEW STRONGER CELLS STILL MAY PRODUCE HAIL/GUSTS NEAR SVR
LEVELS...HOWEVER POTENTIAL IS EXPECTED TO DIMINISH MARKEDLY AFTER
ABOUT 04Z...FROM STABILIZING EFFECTS OF SFC COOLING AND NUMEROUS
OUTFLOWS.
.EDWARDS.. 06/24/2007
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