Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 031729
SWODY2
SPC AC 031728

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CST TUE MAR 03 2015

VALID 041200Z - 051200Z

...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF THE LOWER
MISSISSIPPI VALLEY...

...SUMMARY...
A COUPLE OF SEVERE STORMS MIGHT DEVELOP OVER THE LOWER MISSISSIPPI
VALLEY REGION BEGINNING LATE AFTERNOON WEDNESDAY.

...SYNOPSIS...
PHASING OF A BROAD MULTI-STREAM MID-LEVEL FLOW REGIME IS ANTICIPATED
BY WEDNESDAY NIGHT WITH A POSITIVE-TILT TROUGH BECOMING CENTERED
FROM THE UPPER MIDWEST TO THE SOUTHERN HIGH PLAINS. A COLD FRONT
EXTENDING FROM THE TENNESSEE VALLEY TO NORTH TEXAS AT 04/12Z WILL
PUSH SOUTH AND EAST WITH WESTERN PORTION OF THE BOUNDARY QUITE
PROGRESSIVE AS AN ANTICYCLONE BUILDS SOUTH OVER THE GREAT PLAINS.

...LOWER MISSISSIPPI VALLEY...
LITTLE ADDITIONAL INCREASE IN LOW-LEVEL MOISTURE IS PROGGED IN THE
PRE-FRONTAL WARM SECTOR WITH NEARLY CONSTANT PW VALUES ACROSS THE
GULF AND ADJACENT STATES PER GPS/GOES IMAGERY. MEAN MIXING RATIOS
SHOULD LARGELY RANGE FROM 12-14 G/KG WITH SURFACE DEW POINTS
PREDOMINATELY IN THE MIDDLE 60S. RELATIVELY WARM MID/HIGH-LEVEL
TEMPERATURES WILL YIELD POOR LAPSE RATES /ESPECIALLY WITH EASTWARD
EXTENT/ AND RESULT IN ONLY WEAK INSTABILITY.

THE GEOMETRY OF THE MID-LEVEL TROUGH WITH RESPECT TO THE SHALLOW
FRONTAL ZONE SUGGESTS THAT FORCING FOR ASCENT WILL LARGELY BE
CONFINED TO THE COOL SIDE OF THE BOUNDARY WITH NEAR-NEUTRAL HEIGHT
CHANGE OVER THE WARM SECTOR. WHILE STRONG MID-LEVEL SOUTHWESTERLIES
WOULD BE SUPPORTIVE OF ORGANIZED STORMS IMMEDIATELY ALONG THE
FRONT...THERE SHOULD BE A TENDENCY FOR DEVELOPING CONVECTION TO BE
UNDERCUT...A SCENARIO DEPICTED BY CONVECTION-ALLOWING REFLECTIVITY
SIMULATIONS. WILL MAINTAIN THE INHERITED MARGINAL SEVERE RISK
PROBABILITIES FOR PERHAPS LOCALLY STRONG WIND GUSTS...BUT THE
OVERALL THREAT APPEARS RATHER LOW AND MAY BE DOWNGRADED IN LATER
OUTLOOKS.

..GRAMS.. 03/03/2015



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