Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 220655
SWODY2
SPC AC 220655

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CST MON DEC 22 2014

VALID 231200Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE LOWER MS
VALLEY INTO THE GULF COASTAL STATES...

...THERE IS A MRGL RISK OF SVR TSTMS FROM EXTREME SERN TX THROUGH
THE SERN U.S. AND NRN FL...

...SUMMARY...
A FEW STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE FROM SOUTHERN
PARTS OF THE LOWER MISSISSIPPI VALLEY THROUGH THE GULF COAST STATES
TUESDAY AND TUESDAY NIGHT. THREATS WILL EXIST FOR ISOLATED DAMAGING
WIND GUSTS...LARGE HAIL AND POSSIBLY ISOLATED TORNADOES.

...SYNOPSIS...

HIGH-AMPLITUDE UPPER TROUGH WILL ADVANCE SLOWLY THROUGH THE PLAINS
WITH AN EMBEDDED SRN-STREAM SHORTWAVE TROUGH REACHING THE LOWER MS
VALLEY REGION TUESDAY EVENING. PRECEDING THE SRN-STREAM SHORTWAVE
TROUGH A LEAD IMPULSE WILL EJECT NNEWD INTO THE OH VALLEY AND WRN
PORTIONS OF THE GREAT LAKES. THIS WILL RESULT IN ADVANCE OF COLD
FRONT INTO THE LOWER MS AND WRN TN VALLEYS. THE FRONT MAY STALL OVER
THE LOWER MS VALLEY AS WEAK CYCLOGENESIS OCCURS ALONG TRAILING
PORTIONS OF THIS BOUNDARY...BEFORE ACCELERATING EWD AS THE LOW
DEVELOPS TOWARD THE TN VALLEY OVERNIGHT. A WARM FRONT WILL LIFT NWD
INTO SRN PORTIONS OF THE GULF COAST STATES.

...LOWER MS VALLEY THROUGH THE GULF COASTAL REGION AND NRN FL...

POTENTIAL FOR EARLY CONVECTION REMAINS A COMPLICATING FACTOR THIS
FORECAST AND MAY MITIGATE BOUNDARY-LAYER DESTABILIZATION WITH NWD
EXTENT FROM THE GULF COAST. GREATEST CAPE /1000-1500 J/KG/ EARLY
TUESDAY MAY EXIST FROM SERN TX THROUGH SRN LA EWD ALONG THE GULF
COAST WHERE REMNANT EML WILL RESIDE ABOVE MID 60S F DEWPOINTS. SRN
BRANCH OF SLY LLJ WILL INCREASE OVER THE GULF COAST REGION WITHIN
ZONE OF MODEST HEIGHT FALLS DOWNSTREAM FROM THE SRN-STREAM SHORTWAVE
TROUGH. THETA-E ADVECTION AND ISENTROPIC ASCENT ASSOCIATED WITH THIS
PROCESS WILL LIKELY RESULT IN AN OVERALL INCREASE IN THUNDERSTORMS
EARLY IN PERIOD OVER THE SERN STATES ALONG AND NORTH OF THE COASTAL
WARM FRONT. STORMS DEVELOPING NEAR COAST WILL BE ROOTED AT OR NEAR
THE SFC...WHILE ACTIVITY FARTHER NORTH MAY INITIALLY BE SLIGHTLY
ELEVATED. EFFECTIVE SHEAR FROM 40-50 KT WILL SUPPORT POTENTIAL FOR
ORGANIZED STORMS INCLUDING A FEW SUPERCELLS AND BOWING SEGMENTS.
CONVECTIVE EVOLUTION WILL BE COMPLEX WITH MULTIPLE MODES INCLUDING
CLUSTERS...LINES AND AS WELL AS SOME DISCRETE CELLS POSSIBLE. GIVEN
EXPECTED COMPLEXITY OF THE STORM EVOLUTION AND POTENTIAL FOR EARLY
THUNDERSTORM DEVELOPMENT OVER PORTIONS OF THIS REGION...TOO MUCH
UNCERTAINTY EXISTS TO INTRODUCE MORE THAN 15% SEVERE PROBABILITIES
AT THIS TIME.

..DIAL.. 12/22/2014



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