SWODY2
SPC AC 070539
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1239 AM CDT THU OCT 07 2010
VALID 081200Z - 091200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
THE STRONGER BRANCH OF THE PREVAILING SPLIT UPPER FLOW WILL REMAIN
AMPLIFIED AND MAINLY NORTH OF THE CANADIAN/U.S. BORDER AREA.
MEANWHILE...THE LARGE WRN U.S. CLOSED LOW WHICH WILL BECOME
PROGRESSIVE TRACKING NEWD DURING DAY 1 IS EXPECTED TO REMAIN TIED
MORE TO THE SRN BRANCH ON FRIDAY...MOVING EWD AS A NEGATIVELY-TILTED
TROUGH REACHING THE CENTRAL PLAINS BY 12Z SATURDAY.
...NRN/CENTRAL PLAINS...
A COLD FRONT ATTENDANT TO THE MID-UPPER LEVEL TROUGH WILL SHIFT EWD
ACROSS INTO THE NRN/CENTRAL PLAINS...AND SHOULD EXTEND FROM THE
CENTRAL DAKOTAS SSWWD TO THE CENTRAL/SRN HIGH PLAINS BY 09/00Z. A
SURFACE LOW DEVELOPING ALONG THE NRN EXTENT OF THE FRONT OVER THE
DAKOTAS IS EXPECTED TO STALL OVER THIS REGION FRIDAY NIGHT...WHILE
THE TRAILING FRONT SPREADS EWD INTO THE CENTRAL PLAINS. GIVEN THE
EXISTENCE OF A SURFACE RIDGE EXTENDING SWWD INTO THE WRN GULF COAST
STATES...THE NWD RETURN OF SUBSTANTIAL GULF MOISTURE THROUGH THE
PLAINS IS NOT EXPECTED ON FRIDAY. RESIDUAL MOISTURE IN THE VICINITY
OF A SURFACE BOUNDARY WILL SPREAD NNEWD INVOF A RETREATING WARM
FRONT ACROSS THE MID MO VALLEY TO THE ERN DAKOTAS/MN. GIVEN THE
ORIENTATION OF THE MID-UPPER LEVEL TROUGH WITH A RIDGE SHIFTING EWD
ACROSS THE UPPER MIDWEST AND A STRONG EML/CAP...CONVECTIVE
DEVELOPMENT IS NOT EXPECTED ACROSS THE WARM SECTOR.
MODELS CONTINUE TO SUGGEST THE STRONGEST FORCING FOR ASCENT WILL
TEND TO LAG THE COLD FRONT WITHIN THE POST-FRONTAL ENVIRONMENT. AN
EXCEPTION MAY BE ACROSS THE CENTRAL HIGH PLAINS OF ERN CO INTO WRN
KS FOR SOME SURFACE BASED DEVELOPMENT...BUT THE LACK OF GREATER LOW
LEVEL MOISTURE LIMITING DESTABILIZATION SHOULD PRECLUDE A SEVERE
WEATHER THREAT.
THE GREATEST SEVERE WEATHER THREAT IS EXPECTED TO MAINLY OCCUR
FRIDAY NIGHT OVER THE CENTRAL/WRN DAKOTAS INTO NORTH CENTRAL NEB
INVOF AND WEST OF THE SURFACE LOW/COLD FRONT. THIS ACTIVITY SHOULD
REMAIN ELEVATED AND SUPPORTED BY INCREASING LOW LEVEL MOISTURE/WARM
AIR ADVECTION PER A STRENGTHENING ENELY LLJ AND BENEATH MID-UPPER
LEVEL DIFFLUENT FLOW. MARGINAL INSTABILITY... STEEP MIDLEVEL LAPSE
RATES AND EFFECTIVE BULK SHEAR UP TO 40 KT WILL SUPPORT A THREAT FOR
MAINLY HAIL...POTENTIALLY APPROACHING AND/OR LOCALLY EXCEEDING
SEVERE VALUES. THE WEAK INSTABILITY SHOULD LIMIT THE OVERALL
COVERAGE...AND THUS HAVE ONLY INTRODUCED LOW SEVERE PROBABILITIES.
..PETERS.. 10/07/2010
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