Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 011956
SWODY1
SPC AC 011954

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0254 PM CDT WED OCT 01 2014

VALID 012000Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...CNTRL PLAINS AND OZARKS...

...SUMMARY...
WIDELY SCATTERED SEVERE THUNDERSTORMS CAPABLE OF LARGE HAIL AND
LOCALLY DAMAGING WIND ARE POSSIBLE FROM SOUTH-CENTRAL KANSAS AND
NORTH-CENTRAL OKLAHOMA INTO CENTRAL AND SOUTHERN MISSOURI THIS
AFTERNOON AND EVENING. THE GREATEST RISK FOR A TORNADO OR TWO WILL
EXIST FROM NORTHEAST OKLAHOMA AND SOUTHEAST KANSAS INTO CENTRAL
MISSOURI FROM LATE THIS AFTERNOON INTO EARLY THIS EVENING. A
SEPARATE ROUND OF STRONG TO SEVERE STORMS MAY FORM OVER EASTERN
COLORADO LATE IN THE DAY AND SPREAD EAST INTO PARTS OF WESTERN AND
CENTRAL KANSAS TONIGHT THROUGH EARLY THURSDAY.

THE ONLY CHANGE TO THE OUTLOOK FOR THIS ISSUANCE IS TO EXTEND THE 5
PERCENT TORNADO PROBABILITY ENEWD ACROSS PARTS OF WRN AND CNTRL MO.
THUNDERSTORMS THAT ARE CURRENTLY DEVELOPING ACROSS FAR NE OK AND SE
KS WILL MOVE ALONG THIS CORRIDOR WHERE A STRENGTHENING LOW-LEVEL JET
WILL MAKE CONDITIONS FAVORABLE FOR A COUPLE TORNADOES THROUGH EARLY
THIS EVENING. A CHANGE WAS ALSO CONSIDERED TO REMOVE PARTS OF NRN OK
FROM THE SLIGHT RISK. HOWEVER...THE NAM AND HRRR CONTINUE TO DEVELOP
CONVECTION TO THE NORTH AND WEST OF OKC DUE TO ASCENT ASSOCIATED
WITH THE STRENGTHENING LOW-LEVEL JET AND APPROACHING UPPER-LEVEL
TROUGH AFTER 06Z.

..BROYLES/LINE.. 10/01/2014

.PREV DISCUSSION... /ISSUED 1129 AM CDT WED OCT 01 2014/

...SYNOPSIS...

A LONG-WAVE TROUGH WILL BE MAINTAINED FROM THE INTERIOR WEST THROUGH
GREAT PLAINS WITH SOME AMPLIFICATION OF THIS FEATURE OCCURRING
DURING THE DAY ONE PERIOD. WITHIN THIS BROADER-SCALE REGIME...A
SHORT-WAVE TROUGH OVER THE MID MO VALLEY WILL WEAKEN WHILE EJECTING
NEWD THROUGH THE UPPER GREAT LAKES IN ADVANCE OF A SHORT-WAVE TROUGH
AND ATTENDANT MID AND UPPER-LEVEL WIND MAXIMA WHICH WILL PROGRESS
FROM THE GREAT BASIN TO CNTRL/SRN ROCKIES BY LATE TONIGHT/EARLY
THURSDAY.

AT THE SURFACE...A LOW OVER FAR NWRN OK AS OF MID MORNING MAY DRIFT
SLOWLY E/NE TODAY WHILE AN ASSOCIATED DRYLINE SHARPENS FROM THE
VICINITY OF THIS FEATURE SWWD INTO W-CNTRL TX. MEANWHILE...A WEAK
COLD FRONT/TROUGH WILL CONTINUE EWD THROUGH THE ERN DAKOTAS AND
UPPER MS VALLEY WITH THE TRAILING PORTION OF THIS FRONT OVER WRN KS
BECOMING MORE DIFFUSE WITH THE ONSET OF LEE CYCLOGENESIS OVER SERN
CO LATER TODAY. TONIGHT...A SECONDARY COLD FRONT WILL STRENGTHEN
MARKEDLY WHILE PROGRESSING EWD THROUGH THE NRN PLAINS AND SEWD/SWD
THROUGH THE CNTRL INTO SRN HIGH PLAINS...GRADUALLY OVERTAKING THE
DOWNSTREAM FRONT/DRYLINE.

...CNTRL/SRN PLAINS INTO THE OZARKS THIS AFTERNOON THROUGH
TONIGHT...

12Z REGIONAL SOUNDINGS AND SATELLITE-DERIVED PW IMAGERY INDICATE
THAT ROBUST MOISTURE HAS BECOME ESTABLISHED FROM SRN PORTIONS OF THE
OZARK PLATEAU TO WRN GULF COAST WITH LOWEST 100-MB MEAN-MIXING
RATIOS OF 13-14 G/KG COMMON ACROSS NRN PARTS OF THESE AREAS. AND
WHILE OBSERVED MID-LEVEL LAPSE RATES ARE NOT PARTICULARLY
STEEP...THIS MOISTURE COUPLED WITH DAYTIME HEATING WILL YIELD A
MODERATELY UNSTABLE AFTERNOON AIR MASS WITH MLCAPE APPROACHING
2000-2500 J/KG.

GRADUALLY STRENGTHENING SLY LOW-LEVEL FLOW WILL ENHANCE THE INFLUX
OF THIS INSTABILITY INTO EARLY-DAY STORMS PRESENT OVER NRN INTO
CNTRL MO...LIKELY ALLOWING SOME TO INTENSIFY WHILE BECOMING
SURFACE-BASED ACROSS CNTRL INTO SRN MO LATER TODAY INTO THIS
EVENING. SUFFICIENT VERTICAL SHEAR WILL EXIST FOR ORGANIZED STORM
MODES /INCLUDING SUPERCELLS AND BOWS/ WITH THE PRIMARY HAZARDS BEING
DAMAGING WINDS AND LARGE HAIL.

TO THE SW OF THIS TSTM REGIME FROM S-CNTRL/SERN KS INTO CNTRL
OK...AFTERNOON STORM DEVELOPMENT BECOMES MORE UNCERTAIN OWING TO THE
TENDENCY FOR SLIGHT MID-LEVEL HEIGHT RISES THROUGH THE PEAK OF THE
DIURNAL HEATING CYCLE. AS SUCH...LOW-LEVEL CONVERGENCE INVOF THE
N-CNTRL OK/S-CNTRL KS LOW...ANY RESIDUAL OUTFLOW BOUNDARIES...AND
THE DRYLINE WILL BE THE PRIMARY FOCI FOR ISOLATED TO WIDELY
SCATTERED LATE AFTERNOON/EARLY EVENING STORM DEVELOPMENT. GIVEN
STORM INITIATION...THE PRESENCE OF 40-50 KT EFFECTIVE BULK SHEAR
WILL PROMOTE SUPERCELL DEVELOPMENT WITH THE PRIMARY HAZARD BEING
LARGE HAIL. A TORNADO OR TWO WILL BECOME INCREASINGLY POSSIBLE WITH
ANY SUSTAINED SUPERCELLS OVER SERN KS THIS EVENING OWING TO THE
ENHANCEMENT OF NEAR-GROUND SHEAR BY THE INTENSIFYING LLJ.

TONIGHT INTO EARLY THURSDAY...AN ADDITIONAL CLUSTER OF TSTMS IS
EXPECTED TO EVOLVE ALONG OR IN THE IMMEDIATE WAKE OF THE
STRENGTHENING COLD FRONT ADVANCING ESEWD THROUGH THE CNTRL HIGH
PLAINS. SUFFICIENTLY STRONG VERTICAL SHEAR...INCREASED LARGE-SCALE
FORCING FOR ASCENT...AND MUCAPE OF 1000-2000 J/KG WILL BE SUPPORTIVE
OF A FEW SEVERE STORMS CAPABLE OF DAMAGING WINDS AND SEVERE HAIL.




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