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[Printable]
907
ACUS01 KWNS 222001
SWODY1
SPC AC 221959

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT MON SEP 22 2014

VALID 222000Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR THE CO HIGH PLAINS...

...SUMMARY...
ISOLATED TO SCATTERED THUNDERSTORMS...SOME OF WHICH MAY BE STRONG TO
SEVERE...ARE FORECAST LATE THIS AFTERNOON INTO THE EVENING OVER THE
COLORADO HIGH PLAINS.  A FEW MORE INTENSE THUNDERSTORMS MAY APPROACH
OR BRIEFLY REACH SEVERE LEVELS TODAY OVER PARTS OF THE GEORGIA AND
SOUTH CAROLINA COASTAL PLAIN.

UPGRADED PORTIONS OF THE CO HIGH PLAINS TO A SLIGHT RISK FOR THIS
AFTERNOON AND EARLY EVENING.  THE ONLY OTHER MINOR CHANGE MADE IS TO
THE GENERAL THUNDERSTORM LINE OVER THE SERN STATES TO REFLECT THE
SWD PROGRESSION OF CONVECTION ALONG THE FRONT.

...CO HIGH PLAINS...
VISIBLE SATELLITE AND SURFACE OBSERVATION TRENDS DURING THE
1800-1940Z PERIOD SHOW A CU FIELD DEVELOPING OVER ERN CO AMONGST
SCATTERED CONVECTIVE DEBRIS CLOUDS OWING THEIR ORIGINS TO A
DEPARTING MCV OVER WRN NEB AND ASSOCIATED CONVECTION.  A MOIST AXIS
FROM NERN NM TO NEAR AKO IS DESTABILIZING AS THE RESULT OF SURFACE
HEATING.  A BELT OF STRONG MID-LEVEL WLY FLOW /30-40 KT/ SAMPLED BY
THE ERN CO VAD/VWP NETWORK IS MOVING THROUGH THE BASE OF A SHORTWAVE
TROUGH OVER WY AND WILL BE SUPPORTIVE OF ORGANIZED
STORMS...INCLUDING THE POSSIBILITY FOR SUPERCELLS.  AN ISOLATED
LARGE HAIL THREAT APPEARS GREATER THAN EARLIER FORECAST...PROVIDED
STORMS DEVELOPING OVER THE HIGH TERRAIN AND MOVE EWD INTO THE
PLAINS.  RELATIVELY MOIST LOW-LEVELS COINCIDING WITH A
CLOCKWISE-CURVING HODOGRAPH MAY LOCALLY AUGMENT THE THREAT FOR A
SUPERCELL TORNADO AS WELL.

..SMITH.. 09/22/2014

.PREV DISCUSSION... /ISSUED 1122 AM CDT MON SEP 22 2014/

...SYNOPSIS...

MORNING WATER VAPOR IMAGERY AND 12Z UPPER-AIR DATA INDICATE A
SHORT-WAVE TROUGH OVER THE TN VALLEY WHICH WILL PROGRESS SEWD AND
EVENTUALLY EVOLVE INTO A CLOSED MID-LEVEL CIRCULATION OVER THE
CAROLINAS TOWARD 23/12Z. UPSTREAM FROM THESE DEVELOPMENTS...A
SHORT-WAVE TROUGH OVER THE CNTRL ROCKIES WILL TRANSLATE ENEWD INTO
THE NRN/CNTRL PLAINS...EFFECTIVELY UNDERCUTTING THE MEAN LONG-WAVE
RIDGE IN PLACE WEST OF THE MS VALLEY.

AT THE SURFACE...A COLD FRONT WILL CONTINUE SLOWLY SWD THROUGH THE
SERN U.S...WITH THE POTENTIAL FOR WEAK FRONTAL WAVE DEVELOPMENT AS
LARGE-SCALE FORCING FOR ASCENT IS ENHANCED BY THE SHORT-WAVE TROUGH
MENTIONED ABOVE. ELSEWHERE...A LEE TROUGH WILL STRENGTHEN WHILE
SHIFTING EWD THROUGH THE NRN AND CNTRL HIGH PLAINS.

...SERN STATES THIS AFTERNOON...

A NE-SW-ORIENTED BAND OF SHOWERS AND TSTMS IS ONGOING AS OF MID
MORNING ALONG OR IN THE IMMEDIATE WAKE OF THE COLD FRONT FROM CNTRL
SC TO SERN AL. ABUNDANT SUNSHINE TO THE SOUTH OF THIS ACTIVITY ALONG
WITH BOUNDARY-LAYER DEWPOINTS IN THE 60S WILL SUPPORT AIR MASS
DESTABILIZATION WITH AFTERNOON MLCAPE APPROACHING 1000-1500 J/KG.
THIS INSTABILITY IN CONJUNCTION WITH INCREASING HEIGHT FALLS/DCVA
ASSOCIATED WITH THE MIGRATORY SHORT-WAVE TROUGH SHOULD PROMOTE AN
UPTICK IN CONVECTIVE COVERAGE AND INTENSITY BY AFTERNOON AMIDST A
KINEMATIC ENVIRONMENT FEATURING GRADUALLY STRENGTHENING VERTICAL
SHEAR. AS SUCH...SOME POTENTIAL WILL EXIST FOR MULTICELLS OR LINE
SEGMENTS CAPABLE OF LOCALLY DAMAGING WIND GUSTS AND/OR MARGINALLY
SEVERE HAIL.

...CNTRL HIGH PLAINS THIS AFTERNOON/EVENING...

THE MASS RESPONSE TO THE APPROACHING SHORT-WAVE TROUGH WILL MAINTAIN
A 30-35 KT SLY LLJ ACROSS THE REGION TODAY...WHICH IN TURN WILL
ENHANCE THE POLEWARD FLUX OF LOW-LEVEL MOISTURE E OF THE LEE TROUGH.
CONSIDERABLE EARLY-DAY CLOUDINESS WILL SLOW THE DESTABILIZATION
PROCESS...BUT WHERE CLOUD BREAKS CAN OCCUR...THE INCREASING MOISTURE
MAY YIELD AFTERNOON MLCAPE APPROACHING 500-1000 J/KG. INCREASED
FORCING FOR ASCENT ATTENDANT TO THE MID-LEVEL IMPULSE SHOULD BOLSTER
TERRAIN-INDUCED CIRCULATIONS AND CONVERGENCE IN THE LEE OF THE FRONT
RANGE TO FOSTER WIDELY SCATTERED TSTMS LATER TODAY.

MARGINAL SUPERCELL STRUCTURES ARE POSSIBLE OWING TO A VERTICALLY
VEERING WIND PROFILE WITH DEEP-LAYER SHEAR STRENGTHENING TO 35-45
KT. ISOLATED OCCURRENCES OF LARGE HAIL AND STRONG WIND GUSTS WILL BE
THE PRIMARY HAZARDS...THOUGH A BRIEF TORNADO IS ALSO POSSIBLE.





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