Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS03 KWNS 230715
SWODY3
SPC AC 230715

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0215 AM CDT SAT MAY 23 2015

VALID 251200Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF TX...

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE LOWER MS VALLEY TO THE
UPPER GREAT LAKES...

...SUMMARY...
SCATTERED-NUMEROUS THUNDERSTORMS WILL DEVELOP FROM TEXAS INTO THE
MID SOUTH REGION ON MEMORIAL DAY.  SCATTERED THUNDERSTORMS WILL ALSO
BE NOTED ACROSS MUCH OF THE INTERIOR WEST INTO THE UPPER GREAT LAKES
AND OHIO VALLEY.  GREATEST RISK FOR SEVERE WILL BE ACROSS TEXAS WITH
ISOLATED SEVERE EXTENDING NORTH INTO THE UPPER GREAT LAKES.

...TEXAS...

NRN STREAM MID-LEVEL SPEED MAX IS FORECAST TO DIG SEWD ALONG THE
PACIFIC COAST INTO NRN MEXICO DURING THE DAY2 PERIOD BEFORE EJECTING
INTO THE BIG BEND REGION OF TEXAS EARLY MEMORIAL DAY.  WHILE DEEP
LAYER SHEAR IS NOT FORECAST TO BE PARTICULARLY STRONG...SUFFICIENT
SFC-6KM SHEAR WILL BE PRESENT FOR ORGANIZED CONVECTION AND PERHAPS
SUPERCELL STRUCTURES IF LARGER CONVECTIVE CLUSTERS/LINE SEGMENTS DO
NOT DISRUPT DISCRETE DEVELOPMENT.  TROPICAL PLUME OF HIGH
PW...1.75-2 INCHES...WILL PERSIST ALONG A CORRIDOR FROM THE WRN GULF
BASIN INTO THE MID MS VALLEY REGION.  AS LARGE SCALE FORCING SPREADS
INTO TX CONVECTION SHOULD EASILY DEVELOP...LIKELY EARLY IN THE
PERIOD THEN SPREAD TOWARD THE ARKLATEX.  GIVEN THE LACK OF
MEANINGFUL INHIBITION NUMEROUS STORMS...CLUSTERS AND MERGERS ARE
EXPECTED.  FORECAST SOUNDINGS SUGGEST MULTI-FACETED STORM MODES AND
SUFFICIENT BUOYANCY FOR AT LEAST A THREAT OF LARGE HAIL AND
WIND...PERHAPS EVEN A FEW TORNADOES IF SUPERCELLS EVOLVE.  GIVEN THE
HIGH PW VALUES THESE STORMS WILL LIKELY PRODUCE VERY HEAVY RAINFALL.


...UPPER MS VALLEY/CNTRL PLAINS...

DAY2 SHORT-WAVE TROUGH IS EXPECTED TO EJECT NNEWD INTO THE MID-UPPER
MS VALLEY EARLY IN THE PERIOD IN RESPONSE TO SPEED MAX APPROACHING
THE BIG BEND.  CONVECTION SHOULD DEVELOP AHEAD OF THIS FEATURE EARLY
WITH LARGE SCALE ASCENT LIKELY SPREADING INTO NW ONTARIO BY EARLY
AFTERNOON.  WEAK SHORT-WAVE RIDGING IS EXPECTED ALONG THE TRAILING
FRONTAL ZONE INTO THE CNTRL PLAINS DURING PEAK HEATING.  GIVEN THE
WEAK LARGE SCALE SUPPORT WILL ONLY INTRODUCE 5 PERCENT SEVERE PROBS
ACROSS THIS REGION FOR ISOLATED SUPERCELLS THAT EVOLVE DURING THE
LATE AFTERNOON AND LINGER INTO THE EVENING HOURS.

..DARROW.. 05/23/2015



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