Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
ACUS01 KWNS 060556
SWODY1
SPC AC 060555

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT WED MAY 06 2015

VALID 061200Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING FROM
WESTERN-NORTH TX THROUGH THE WESTERN HALF OF OK...THE FAR EASTERN TX
PANHANDLE...CENTRAL KS AND SOUTH-CENTRAL NEB...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK AREA
ACROSS THE SOUTHERN AND CENTRAL PLAINS...

...SUMMARY...
ISOLATED TO SCATTERED SEVERE STORMS WILL BE POSSIBLE LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF THE CENTRAL AND SOUTHERN
PLAINS.

...SYNOPSIS...
WITHIN CYCLONIC WESTERLIES OVER THE WESTERN HALF OF THE CONTIGUOUS
UNITED STATES TODAY...A LEAD SHORTWAVE TROUGH WILL TRACK
NORTHEASTWARD ACROSS THE CENTRAL PLAINS WHILE UNDERGOING
DE-AMPLIFICATION ESPECIALLY DURING THE LATTER HALF OF THE FORECAST
PERIOD INTO THE DAKOTAS/UPPER MIDWEST.  MEANWHILE...A LARGER SCALE
TROUGH IS EXPECTED TO DIG SWD FROM THE PACIFIC NORTHWEST WITH A
CLOSED LOW FORMING WEDNESDAY NIGHT...CENTERED OVER NRN/CENTRAL CA.
THIS EVOLUTION OCCURRING UPSTREAM FROM A MEAN RIDGE POSITIONED FROM
THE WESTERN GULF TO THE GREAT LAKES IS EXPECTED TO SUSTAIN A S/SWLY
MID/UPPER-LEVEL FLOW REGIME FROM THE SRN HIGH PLAINS TO THE UPPER
MIDWEST.  FARTHER EAST...A MID/UPPER LEVEL TROUGH WILL MOVE NNEWD
FROM FL WITH A CLOSED LOW FORMING OFF THE GA/SC COAST BY WEDNESDAY
NIGHT.

AT THE SURFACE...A DRY LINE IS EXPECTED TO MIX EWD TODAY THROUGH
WESTERN NORTH TX...WRN OK AND INTO CENTRAL KS THIS AFTERNOON.
FARTHER NORTH...A COLD FRONT WILL MOVE EASTWARD ACROSS THE NORTHERN
PLAINS TONIGHT.

...CENTRAL/SOUTHERN PLAINS...
WARM-CONVEYOR SCATTERED SHOWERS/TSTMS WILL BE ONGOING AT 12Z TODAY
FROM PARTS OF NORTHEAST TX AND EASTERN OK NWD INTO THE MID MO
VALLEY.  RESIDUAL CLOUD COVER IS EXPECTED ACROSS MUCH OF THE
WARM/MOIST SECTOR INTO THIS AFTERNOON.  MEANWHILE...SLY LOW-LEVEL
WINDS WILL MAINTAIN POLEWARD MOISTURE RETURN/THETA-E ADVECTION EAST
OF THE DRY LINE...WITH PW VALUES EXCEEDING 1.25 INCHES.  THIS
COMBINED WITH SURFACE HEATING WEST OF THE EARLY DAY CLOUDINESS WILL
CONTRIBUTE TO A DESTABILIZING AIR MASS WITH MLCAPE OF 1500-2500 J/KG
FROM SOUTH-CENTRAL KS SWD THROUGH WRN OK AND WRN/CENTRAL TX...WHILE
VALUES OF 1000-1500 J/KG NWD THROUGH CENTRAL KS AND SRN/ERN NEB.
EFFECTIVE BULK SHEAR OF 35-40 KT IS EXPECTED ALONG THE FULL EXTENT
OF THE DRY LINE WITH THIS SHEAR VECTOR ORIENTED PERPENDICULAR TO
THIS BOUNDARY WHICH SUPPORTS SUPERCELLS WITH STORMS THAT DEVELOP
LATE THIS AFTERNOON INTO THE EVENING.

MODELS CONTINUE TO INDICATE MUCH OF THE LEAD SHORTWAVE
TROUGH-RELATED LARGE-SCALE FORCING FOR ASCENT WILL OVERSPREAD THE
CENTRAL PLAINS/MIDDLE MO VALLEY...WHILE NEUTRAL HEIGHT TENDENCIES OR
WEAK RISES...WITH SOME MIDLEVEL WARMING WILL OCCUR ACROSS THE
SOUTHERN PLAINS PORTION OF THE DRYLINE.  GIVEN THIS FACTOR AND
GUIDANCE FROM THE HIGH-RES MODELS AND CAMS SUGGEST STORM COVERAGE
NEAR AND EAST OF THE DRY LINE WILL TEND TO BE ISOLATED...WHICH
CONTINUES TO SUPPORT A SLIGHT RISK FOR SEVERE STORMS...AND NO
INCLUSION OF AN ENHANCED RISK AREA AS THIS TIME.  SEVERE HAIL AND
DAMAGING WINDS MAY BE THE MOST COMMON RISKS...WITH A PLUME OF
STEEPER MIDLEVEL LAPSE RATES SPREADING ACROSS TX/OK/KS PORTIONS OF
THE SLIGHT RISK AREA THIS EVENING SUGGESTING VERY LARGE HAIL WILL BE
POSSIBLE.  VERTICALLY VEERING WIND PROFILES WILL SUPPORT A TORNADO
THREAT.  FORECAST SOUNDINGS INDICATED SOME BACKING OF LOW-LEVEL
WINDS ACROSS WRN-NORTH TX THROUGH WRN OK INTO SOUTH CENTRAL KS THIS
EVENING AS THE DRY LINE RETREATS WITH A TORNADO IN THOSE AREAS AS
WELL WITH ANY STORMS THAT DEVELOP.

..PETERS/MOSIER.. 05/06/2015



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.