DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 230535
SWODY1
SPC AC 230533

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1233 AM CDT THU AUG 23 2012

VALID 231200Z - 241200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
WESTERLIES OF AT LEAST MODEST STRENGTH ARE ONCE AGAIN BECOMING
CONFINED TO THE CANADIAN/U.S. BORDER AREA...BUT A BELT OF WEAK
WESTERLY FLOW IS EXPECTED TO PERSIST THROUGH THIS PERIOD ACROSS
LOWER LATITUDES OF THE U.S...BETWEEN PROMINENT HIGH CENTERS OVER THE
SUBTROPICAL CENTRAL ATLANTIC AND EASTERN PACIFIC. REMNANT BROADER
SCALE TROUGHING WITHIN THIS SOUTHERN STREAM MAY BEGIN TO GRADUALLY
DEVELOP EASTWARD ACROSS MID/SOUTH ATLANTIC COASTAL AREAS...AND
ACROSS THE FOUR CORNERS STATES...WHILE SEVERAL NOTABLE SHORT WAVE
TROUGHS PROGRESS THROUGH THE STRONGER BELT TO THE NORTH.

THE STRONGEST OF THESE LATTER FEATURES IS EXPECTED TO DIG TO THE
SOUTHEAST OF THE CANADIAN ROCKIES TODAY...AND APPEARS LIKELY TO BE
ACCOMPANIED BY SIGNIFICANT SURFACE CYCLOGENESIS LATE TODAY INTO
FRIDAY ACROSS THE CANADIAN PRAIRIES. AN ASSOCIATED SURFACE LOW
CENTER MAY FORM OVER SOUTHEASTERN MONTANA LATE THIS AFTERNOON INTO
TONIGHT...BUT MOISTURE RETURN TO THE NORTHERN HIGH PLAINS WILL BE
SLOW TO OCCUR IN THE WAKE OF A DOWNSTREAM SHORT WAVE IMPULSE
PROGRESSING ACROSS THE UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION.
MOISTURE DOES APPEAR LIKELY TO CONTINUE TO INCREASE ON SOUTHERLY
LOW-LEVEL FLOW FROM THE SOUTHERN INTO THE CENTRAL PLAINS...HOWEVER
GUIDANCE IS SUGGESTIVE THAT THE LOW-LEVEL WIND SHIFT ACCOMPANYING
THE LEAD IMPULSE MAY CUT OFF FURTHER MOISTURE ADVECTION NORTHWARD
INTO THE UPPER MISSISSIPPI VALLEY/GREAT LAKES.

...CENTRAL PLAINS...
MID-LEVEL FLOW ACROSS THE LEE SURFACE TROUGH IS EXPECTED TO REMAIN
RATHER WEAK TODAY...BUT A MODERATELY STRONG SOUTHERLY LOW-LEVEL JET
/30-40 KT AT 850 MB/ MAY CONTRIBUTE TO CONVECTIVE POTENTIAL ACROSS
WESTERN KANSAS AND PORTIONS OF ADJACENT STATES LATE THIS AFTERNOON
AND EVENING. IT APPEARS THAT SURFACE HEATING AND INCREASING
LOW-LEVEL MOISTURE BENEATH STEEP MID-LEVEL LAPSE RATES MAY
CONTRIBUTE TO MIXED LAYER CAPE ON THE ORDER OF 2000 J/KG. AND
INHIBITION IS EXPECTED TO WEAKEN SUFFICIENTLY BY LATE AFTERNOON FOR
THE INITIATION OF STORMS. ALTHOUGH NOT PARTICULARLY HOT OR DEEPLY
MIXED...BOUNDARY LAYER PROFILES STILL APPEAR FAVORABLE FOR ONE OR
TWO DOWNBURSTS AND SURFACE COLD POOL DEVELOPMENT...ACCOMPANIED BY A
FEW STRONG SURFACE GUSTS BEFORE ACTIVITY WEAKENS DURING THE EVENING
HOURS.

...UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION...
MODESTLY STRONG SOUTHERLY LOW-LEVEL FLOW /30-40 KT AT 850 MB/ AND
STEEPENING MID-LEVEL LAPSE RATES WILL CONTRIBUTE TO CONVECTIVE
POTENTIAL ALONG/AHEAD OF THE SURFACE WIND SHIFT ACCOMPANYING THE
SHORT WAVE TROUGH. MID-LEVEL FLOW...HOWEVER...IS EXPECTED TO REMAIN
FAIRLY WEAK...AND UNCERTAINTY EXISTS CONCERNING LOW-LEVEL MOISTURE
AND INSTABILITY. STILL...MOISTURE CURRENTLY PRESENT ACROSS THE
REGION APPEARS SUPPORTIVE OF AT LEAST POCKETS OF MODERATELY LARGE
CAPE BY LATE AFTERNOON...WHICH MAY BE ACCOMPANIED BY ISOLATED TO
WIDELY SCATTERED STRONG/SEVERE STORM DEVELOPMENT.

..KERR/ROGERS.. 08/23/2012

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