DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201959
SWODY1
SPC AC 201957

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT TUE AUG 20 2013

VALID 202000Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

--- UPDATES ---
LITTLE ADJUSTMENT IS NEEDED TO ANY CATEGORICAL OR PROBABILISTIC
LINES AT THIS UPDATE CYCLE. ON MESOSCALE...SEVERAL AREAS OF
EARLY-STAGE CONVECTION HAVE BECOME EVIDENT IN ASSOCIATION WITH
NRN-PLAINS AREA OF MRGL SVR PROBABILITIES -- INCLUDING YOUNG TSTMS
OVER NRN BLACK HILLS. PRECONVECTIVE/PREFRONTAL AIR MASS SHOULD
CONTINUE TO DESTABILIZE FOR ANOTHER COUPLE HOURS OR SO IN SUPPORT OF
WIDELY SCATTERED TSTMS AND ISOLATED SVR THREAT FROM BLACK HILLS
REGION NEWD ACROSS NRN MN. REF SPC MESOSCALE DISCUSSION 1740 FOR
ADDITIONAL/NEAR-TERM DETAILS.

..EDWARDS.. 08/20/2013

.PREV DISCUSSION... /ISSUED 1058 AM CDT TUE AUG 20 2013/

...SYNOPSIS...
THE WLYS WILL REMAIN CONFINED TO CNTRL AND SRN CANADA THIS
PERIOD...WITH ONLY MINIMAL INFLUENCE EXTENDING SWD INTO THE FAR NRN
CONUS. A SERIES OF LOW-AMPLITUDE DISTURBANCES CROSSING THE CANADIAN
PRAIRIES WILL HELP A WEAK COLD FRONT ADVANCE E/SE ACROSS MT/ND/NRN
MN...WHILE A TROUGH AHEAD OF THE FRONT EDGES MORE SLOWLY SE ACROSS
WRN NEB AND CNTRL SD. OTHERWISE...AN UPR LOW IS EXPECTED TO REMAIN
QSTNRY OFF THE SRN/CNTRL CA CST...AS ANOTHER MOVES SLOWLY E FROM
CNTRL/SRN IL INTO IND. RELATIVELY WEAK MID-LVL LAPSE RATES AND
MODEST MID-TROPOSPHERIC FLOW SHOULD LIMIT SVR POTENTIAL THROUGH
EARLY WEDNESDAY.

...ERN WY/NW NEB TO UPR MS VLY THIS AFTN INTO TNGT...
STRONG SFC HEATING WILL OCCUR ALONG/AHEAD OF TROUGH AND COLD FRONT
CROSSING THE N CNTRL STATES TODAY. COUPLED WITH FAIRLY RICH LOW-LVL
MOISTURE/PW AOA 1.25 INCHES...EXPECT MLCAPE TO RANGE FROM 1000 TO
LOCALLY 2000 J/KG FROM FAR ERN WY/NW NEB NEWD INTO MUCH OF SD...SE
ND...AND MN BY MID-LATE AFTN.

SATELLITE AND MODEL FCSTS INDICATE THAT UPR-LVL FORCING FOR ASCENT
WILL BE NEUTRAL TO NEGATIVE OVER ERN WY/NEB AND MOST OF SD.
NEVERTHELESS...LOW-LVL UPLIFT ALONG SFC TROUGH AND DEGREE OF
BUOYANCY SUGGEST POTENTIAL FOR SCTD PULSE STORMS/STORM CLUSTERS
CAPABLE OF ISOLD DMGG WIND GUSTS AND/OR MARGINALLY SVR HAIL IN THE
WEAKLY-SHEARED ENVIRONMENT.

FARTHER N...SOMEWHAT GREATER /30+ KT/ WNWLY DEEP SHEAR WILL DEVELOP
THIS AFTN INTO TNGT ALONG COLD FRONT OVER ND AND NRN/WRN MN. COUPLED
WITH AT LEAST GLANCING INFLUENCE FROM THE DISTURBANCES CROSSING SRN
CANADA...A CONDITIONAL RISK WILL EXIST FOR A FEW SUSTAINED/MORE
STRONGLY ORGANIZED STORMS IN THAT REGION. NEVERTHELESS...GIVEN
MODEST LAPSE RATES AND LIMITED HEIGHT FALLS...LIKELIHOOD FOR A
SUBSTANTIAL SVR WEATHER EVENT APPEARS LOW.

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