DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 140454
SWODY2
SPC AC 140453

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1153 PM CDT THU SEP 13 2012

VALID 151200Z - 161200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
UPPER-AIR PATTERN THIS PERIOD WILL REMAIN DOMINATED BY ANTICYCLONE
OVER GREAT BASIN REGION...PROGRESSIVE NRN-STREAM SHORTWAVES...AND
PERSISTENT/WEAK TROUGHING FROM WRN MEX NEWD ACROSS NM AND SRN KS.
LATTER FEATURE IS EXPECTED TO UNDERGO NET SEWD DRIFT...WHILE
EMBEDDED VORTICITY MAXIMUM EVOLVES INTO SMALL/WEAK/CLOSED/500-MB
CYCLONE. GIVEN MESOSCALE NATURE OF VORTICITY FEATURES ASSOCIATED
WITH THIS PERTURBATION...AND AMBIENT WEAKNESS OF BOTH FLOW AND
THERMAL FEATURES ALOFT...IT IS NOT SURPRISING THAT MODELS VARY
CONSIDERABLY ON TIMING AND TRACK OF THAT LOW...PROGGED AT 16/12Z
OVER TRANS-PECOS REGION BY NAM AND NEAR CDS BY SPECTRAL. RANGE OF
SREF SOLUTIONS IS EVEN GREATER. BETTER AGREEMENT EXISTS WITH
WELL-DEFINED/NRN-STREAM PERTURBATION WITH EMBEDDED CYCLONE NOW
CROSSING NWRN ONT OVER BOUNDARY WATERS/THUNDER BAY REGION. AS THAT
FEATURE SHIFTS EWD...ATTACHED MID-UPPER TROUGH SHOULD REACH ERN
NY/WRN NEW ENGLAND AROUND 15/12Z...THEN MOVE EWD OUT OF MAINE BEFORE
END OF PERIOD. MEANWHILE...SHORTWAVE TROUGH IS FCST TO DEVELOP OVER
WRN CANADA...MOVING SEWD ACROSS PORTIONS MB/SK AND PERHAPS REACHING
ND/CANADA LINE BY END OF PERIOD.

AT SFC...COLD FRONT ASSOCIATED WITH CANADIAN PERTURBATION SHOULD
CROSS MT...MOST OF ND...AND PORTIONS SD/NWRN MN THIS PERIOD.
FRONTAL-WAVE LOW SHOULD FORM BY 16/12Z OVER SD. OLDER COLD FRONT --
NOW DRAWN FROM LOWER GREAT LAKES SWWD ACROSS INDIANA...WRN/NRN
AR...AND S-CENTRAL TX -- SHOULD MOVE EWD OFFSHORE NEW ENGLAND EARLY
IN PERIOD...WHILE BECOMING QUASISTATIONARY AND DIFFUSE FROM PORTIONS
MS/AL SWWD ACROSS S TX. MORE SPECIFIC LOCATION OF THIS BOUNDARY IS
HIGHLY UNCERTAIN THIS FAR OUT...GIVEN WEAKNESS OF LOW-LEVEL
WINDS...LIKELIHOOD OF MESOSCALE CONVECTIVE ADJUSTMENTS TO
BAROCLINICITY BETWEEN NOW AND THEN...AND AFOREMENTIONED DIFFERENCES
IN PROGS OF PROXIMAL UPPER FEATURES.

...ERN OK/WRN AR/NE TX...
WIDELY SCATTERED TO SCATTERED TSTMS MAY DEVELOP OVER THIS REGION
ANYTIME DURING PERIOD. SOME POTENTIAL EXISTS FOR SFC-BASED
CONVECTION IN AREAS THAT MAY BE DIABATICALLY HEATED DURING DAY WITH
SUBSTANTIAL WEAKENING OF MLCINH. REGIME OF BROAD/WEAK MOIST
ADVECTION AND TRANSPORT SHOULD BE IN PLACE AMIDST LOW-LEVEL SELY/SLY
FLOW...RESULTING IN 60S F SFC DEW POINTS. FCST SOUNDINGS
ACCOMPANYING MORE NERN/PROGRESSIVE SCENARIO FOR MID-UPPER
PERTURBATION OFFER SUFFICIENT DEEP-LAYER BULK SHEAR AND LOW-LEVEL
DIRECTIONAL SHEAR FOR SOME ORGANIZED MULTICELL/MRGL SUPERCELL
CONCERN OVER THIS REGION. WEAK LAPSE RATES AND LACK OF SUBSTANTIAL
LOW-LEVEL FLOW WILL BE LIMITING FACTORS. FURTHER UNCERTAINTIES
PRECLUDING UNCONDITIONAL SVR PROBABILITIES ATTM INVOLVE FEATURE
ALOFT...AND BY EXTENSION CHARACTER/POSITIONING OF ANY
SUBTLE/LOW-LEVEL TSTM FOCI.

..EDWARDS.. 09/14/2012

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