SWODY1
SPC AC 160558
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1158 PM CST SUN JAN 15 2012
VALID 161200Z - 171200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A BROAD LONGWAVE TROUGH IS EXPECTED TO EVOLVE ACROSS MUCH OF THE
CONUS THIS FORECAST PERIOD AS AN UPPER TROUGH...NOW MOVING SEWD
THROUGH THE PACIFIC NW PER WATER VAPOR IMAGERY...SHIFTS EWD ACROSS
THE CENTRAL ROCKIES INTO THE CENTRAL PLAINS BY 12Z TUESDAY.
MEANWHILE...A LOW AMPLITUDE SHORTWAVE TROUGH...CURRENTLY MOVING
ONSHORE FAR SRN CA/NRN BAJA REGION...IS EXPECTED TO WEAKEN DURING
THE FIRST HALF OF THE DAY AS IT MOVES INTO A CONFLUENT FLOW REGIME
OVER THE SWRN STATES/SRN HIGH PLAINS. FURTHER WEAKENING IS EXPECTED
MONDAY NIGHT AS THE REMAINS OF THIS TROUGH UNDERGO ADDITIONAL
SHEARING TRACKING THROUGH AR/SRN MO TO THE LOWER OH VALLEY.
AT 12Z MONDAY...A COLD FRONT WILL EXTEND SWWD FROM THE UPPER MS
VALLEY THROUGH IA TO A SURFACE LOW LOCATED IN EAST CENTRAL KS...WITH
THE FRONT THEN EXTENDING WWD INTO SERN CO. THE LOW WILL TRACK NEWD
THROUGH THE MID MS VALLEY TO LOWER MI ALONG THE EWD ADVANCING COLD
FRONT. THE TRAILING PORTION OF THE FRONT SHOULD REMAIN NEARLY
STATIONARY THROUGH THE AFTERNOON...AND THEN MOVE SWD TO THE RED
RIVER VALLEY BY 12Z TUESDAY.
...FAR SERN KS/ERN OK THROUGH AR/SRN MO TO LOWER OH VALLEY...
SSWLY LOW LEVEL WINDS WILL ADVECT MOISTURE NWD THIS FORECAST PERIOD
BENEATH AN ELEVATED MIXED LAYER...WHICH WILL EFFECTIVELY CAP THE
PRE-FRONTAL AIR MASS THROUGH THE FIRST HALF OF THE FORECAST
PERIOD...PRECLUDING DEEP MOIST CONVECTION UNTIL MONDAY NIGHT.
FURTHER MOISTENING/LOW LEVEL WAA COMBINED WITH WEAK HEIGHT FALLS
WITH THE APPROACH OF THE NWRN TROUGH SUGGEST THE POTENTIAL EXISTS
FOR SUFFICIENT WEAKENING OF THE CAP TO SUPPORT PARCELS ROOTED AT THE
SURFACE...OR AT LEAST NEAR SURFACE BASED. THIS POTENTIAL WILL BE
GREATEST OVER AR BETWEEN 17/00-06Z...WITH ADDITIONAL CONVECTION
POSSIBLE ALONG THE FRONT AS IT ADVANCES SSEWD INTO SERN KS/SRN MO
MONDAY EVENING.
MODEL DIFFERENCES IN THE DEGREE OF FORCING FOR ASCENT/HEIGHT FALLS
ACROSS THE WARM SECTOR...LACK OF GREATER MOISTURE RETURN...AND
SOMEWHAT LIMITED LOW LEVEL CONVERGENCE AS 850 MB FLOW VEERS TO SWLY
/PARALLEL TO THE FRONT/ PRECLUDES THE INCLUSION OF HIGHER SEVERE
PROBABILITIES WITH THIS OUTLOOK. GIVEN STRONG WIND FIELDS...DEEP
LAYER AND LOW LEVEL SHEAR WILL BE SUFFICIENT FOR ROTATING
UPDRAFTS...AND THUS PROVIDES THE REASON TO MAINTAIN LOW SEVERE
WEATHER PROBABILITIES.
...PARTS OF E TX/LA/SRN MS...
FORCING ALOFT WILL BE MUCH WEAKER WITH TSTMS POSSIBLE AFTER MIDNIGHT
INTO EARLY TUESDAY SUPPORTED MAINLY BY LOW LEVEL WAA. WEAKER DEEP
LAYER SHEAR SHOULD GREATLY LIMIT THE SEVERE WEATHER THREAT ACROSS
THESE AREAS THROUGH 12Z TUESDAY.
..PETERS/DEAN.. 01/16/2012
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