SWODY2
SPC AC 141730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT WED MAR 14 2012
VALID 151200Z - 161200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A HIGHLY UNPREDICTABLE MESOSCALE PATTERN FOR MID-MARCH RENDERS
BELOW-AVERAGE CONFIDENCE IN CONVECTIVE DETAILS FOR A D2 FORECAST. ON
THE SYNOPTIC SCALE...A MID-LEVEL RIDGE WILL SHIFT EWD FROM THE LOWER
GREAT LAKES ACROSS NEW ENGLAND. PRIMARY BELT OF STRONGER WLYS WILL
BE CONFINED TO THE PACIFIC NW ACROSS THE CANADIAN PRAIRIES. A FEW
MINOR IMPULSES IN THE SRN STREAM SHOULD MOVE ACROSS NWRN MEXICO TO
THE TN VALLEY. AT THE SURFACE...A WEAK COLD FRONT SHOULD BECOME
QUASI-STATIONARY ACROSS PARTS OF THE CNTRL GREAT LAKES TO THE CORN
BELT. A DRYLINE WILL REMAIN ESTABLISHED FROM THE CNTRL TO THE SRN
HIGH PLAINS.
...MID-SOUTH/TN VALLEY...
ALTHOUGH GUIDANCE VARIES WITH THE AMPLITUDE OF A WEAK MID-LEVEL
IMPULSE EJECTING EWD FROM NM...THERE IS CONSISTENCY THAT AN
ATTENDANT SPEED MAX WOULD OVERSPREAD THE MID-SOUTH AND PERHAPS INTO
THE TN VALLEY ON THU. THE GFS REMAINS THE MOST AMPLIFIED OF THE
DETERMINISTIC MODELS WITH A SMALL BELT OF 30-40 KT FLOW AT 500 MB ON
THU AFTERNOON. SHOULD THIS INDEED OCCUR...A MODERATELY UNSTABLE AIR
MASS AND ASCENT ASSOCIATED WITH THE IMPULSE COULD YIELD ONE OR MORE
ORGANIZED TSTM CLUSTERS CAPABLE OF DAMAGING WINDS AND SEVERE HAIL.
WILL INTRODUCE 5 PERCENT SEVERE PROBABILITIES TO THIS REGION...AND
SHOULD CONFIDENCE IN THE ABOVE SCENARIO INCREASE...AN UPGRADE TO
SLIGHT RISK WOULD SEEM PROBABLE IN LATER OUTLOOKS.
...GREAT LAKES/MIDWEST/OH VALLEY...
A WEAK QUASI-STATIONARY FRONT SHOULD EXTEND ACROSS LOWER MI TOWARDS
THE WI/IL BORDER ON THU AFTERNOON. GUIDANCE SUGGESTS THAT SURFACE
DEW POINTS WILL REACH THE UPPER 50S TO LOWER 60S WITHIN THE WARM
SECTOR...AND IN CONJUNCTION WITH STEEP LAPSE RATES COULD SUPPORT
MODERATE TO STRONG INSTABILITY WITH MLCAPE OF 1500-3000 J/KG. THE
LACK OF AN APPARENT IMPULSE/SPEED-MAX WOULD SUGGEST FORCING FOR
ASCENT /BEYOND THE SURFACE BOUNDARY/ AND KINEMATIC PROFILES WILL
REMAIN WEAK. WITH EFFECTIVE SHEAR PERHAPS ONLY REACHING 10-20
KT...STORM-SCALE ORGANIZATION AND COVERAGE MAY REMAIN LIMITED. AS
SUCH...A CATEGORICAL SLIGHT RISK DOES NOT APPEAR WARRANTED ATTM.
...MID MO VALLEY TO THE SRN HIGH PLAINS...
A MODERATE TO STRONGLY UNSTABLE AIR MASS SHOULD BE PREVALENT WITHIN
THE WARM SECTOR AS SURFACE DEW POINTS FROM THE UPPER 50S TO LOWER
60S ANCHORED ALONG THE DRYLINE. STRONG HEATING SHOULD RESULT IN
MINIMAL CONVECTIVE INHIBITION BY LATE AFTERNOON. HOWEVER...MUCH OF
THE PLAINS SHOULD LIE IN BETWEEN TWO WEAK SRN STREAM IMPULSES DURING
THIS TIME FRAME /ONE MOVING TOWARDS THE MID-SOUTH AND THE OTHER BACK
IN NWRN MEXICO/. AN ISOLATED TSTM OR TWO COULD FORM TOWARDS THE BIG
BEND AREA IN ASSOCIATION WITH THE LATTER IMPULSE.
ELSEWHERE...CONVERGENCE ALONG THE DRYLINE SHOULD BE MEAGER AS WEAK
AND VEERED LOW-LEVEL FLOW PREVAILS THROUGH THE WARM SECTOR. TSTM
DEVELOPMENT SEEMS RATHER UNLIKELY AND GIVEN PROBABLE MARGINAL
SHEAR...A CATEGORICAL SLIGHT RISK DOES NOT APPEAR NECESSARY.
..GRAMS.. 03/14/2012
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