DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 231252
SWODY1
SPC AC 231250

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0750 AM CDT THU AUG 23 2012

VALID 231300Z - 241200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
WEAK ZONAL FLOW WILL PREVAIL OVER THE MOST OF THE CONUS THIS
PERIOD...THE EXCEPTION BEING THE PACIFIC NW...WHERE STRONGER WLY
WINDS WILL PREVAIL ON SRN FRINGE OF PROGRESSIVE BC LOW. FARTHER
DOWNSTREAM IN THE SAME JET...A WEAKER...NEGATIVE-TILT DISTURBANCE
WILL CONTINUE E FROM SK/SRN MB INTO WRN ONT/THE UPR GRT LKS...WHILE
ANOTHER NOW CROSSING QUE GLANCES NRN NEW ENGLAND. ELSEWHERE...UPR
LOW/TROUGH NOW OVER THE LWR CO VLY SHOULD FURTHER WEAKEN AS IT
SHEARS ENE ACROSS THE FOUR CORNERS INTO THE SRN RCKYS. AT THE SAME
TIME...A SERIES OF WEAK DISTURBANCES WILL TRACK NE WITHIN REMNANT
LARGER-SCALE TROUGH ALONG THE S ATLANTIC CST.

AT THE SFC...APPROACH OF BC UPR LOW WILL STRENGTHEN LEE TROUGH AND
INDUCE CYCLOGENESIS OVER THE NRN HI PLNS. MOISTURE RETURN TO THE
REGION WILL...HOWEVER...REMAIN SCANT IN THE WAKE OF DOWNSTREAM
DISTURBANCE NOW ENTERING MB. STRENGTHENING LEE TROUGH WILL INCREASE
SLY LLJ/MOISTURE TRANSPORT INTO THE CNTRL PLAINS...BUT MOISTURE
RETURN WILL REMAIN MORE LIMITED NEWD INTO THE UPR MS VLY/UPR GRT
LKS.

...CNTRL PLNS THIS AFTN THROUGH TNGT...
MID-LVL WLY FLOW ABOVE LEE TROUGH WILL REMAIN WEAK TODAY. BUT 30-40
KT SLY LLJ MAY ENHANCE CONVECTIVE POTENTIAL ACROSS WRN KS AND PARTS
OF ADJACENT STATES LATE THIS AFTN INTO TNGT. SFC HEATING AND
INCREASING LOW-LVL MOISTURE BENEATH EML MAY YIELD MLCAPE AROUND 2000
J/KG. INHIBITION SHOULD SUFFICIENTLY WEAKEN FOR STORM INITIATION BY
LATE AFTN. WHILE NOT PARTICULARLY HOT OR DEEPLY MIXED...LOW-LVL
THERMODYNAMIC SETUP STILL APPEARS FAVORABLE FOR A FEW DOWNBURSTS
WITH LOCALLY DMGG WIND.

FOCUSED CONVERGENCE ALONG WEAK LEE TROUGH AND WIND SHIFT EXTENDING
NE TOWARD THE UPR MS VLY SUGGESTS POTENTIAL THAT STORM COLD POOLS
WILL MERGE...YIELDING AS A SIZABLE...SSE-MOVING MCS OR TWO OVER
WRN/CNTRL KS AND S CNTRL NEB BY EVE. MCS DEVELOPMENT ALSO WILL BE
FOSTERED BY ASCENT ON LEADING EDGE OF SYSTEM APPROACHING FROM THE
FOUR CORNERS. WHILE ISOLD DMGG WIND GUSTS MAY CONTINUE TO
OCCUR...WEAK MID LVL FLOW ARGUES AGAINST AN UPGRADE TO SLIGHT RISK
ATTM.

...UPR MS VLY/UPR GRT LKS THIS AFTN/EVE...
30-40 KT SSWLY 850 MB FLOW AND STEEPENING MID-LVL LAPSE RATES WILL
CONTRIBUTE TO CONVECTIVE POTENTIAL ALONG/AHEAD OF SFC WIND SHIFT
ACCOMPANYING MB UPR TROUGH. MID-LVL WINDS WILL...HOWEVER...REMAIN
FAIRLY WEAK...AND LOW-LVL MOISTURE LIMITED. NEVERTHELESS...POCKETS
OF MODERATE INSTABILITY SHOULD DEVELOP /MLCAPE TO 1500 J PER KG/ IN
AREAS OF STRONGEST HEATING AWAY FROM ELEVATED MORNING STORMS.
COUPLED WITH AT LEAST WEAK FORCING FOR ASCENT IN SRN PART OF UPR
IMPULSE...SETUP MAY YIELD ISOLD TO PERHAPS WDLY SCTD STORMS WITH
LOCALLY DMGG WIND AND/OR MARGINALLY SVR LATER THIS AFTN INTO THIS
EVE.

..CORFIDI/HURLBUT.. 08/23/2012

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