Severe Storm Outlook Narrative (AC)
Issued by NWS

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 260601
SWODY1
SPC AC 260600

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT SUN APR 26 2015

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTHERN PLAINS TO
PARTS OF WESTERN/SOUTHERN AR AND NORTHERN LA...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLIGHT RISK
AREA FROM THE SOUTHERN PLAINS TO THE LOWER MS VALLEY...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE SOUTHEAST
STATES...

...SUMMARY...
SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP
ACROSS THE SOUTHERN PLAINS THIS AFTERNOON AND CONTINUE INTO THE
OVERNIGHT HOURS.  ISOLATED STRONG TO POTENTIALLY SEVERE STORMS MAY
ALSO DEVELOP ACROSS THE SOUTHEAST STATES.

...SYNOPSIS...
A MID- TO UPPER-LEVEL TROUGH...CURRENTLY LOCATED ACROSS THE LOWER CO
RIVER VALLEY PER WATER VAPOR IMAGERY...WILL MIGRATE EWD THIS
FORECAST PERIOD ACROSS AZ/NM...LIKELY EVOLVING INTO A CLOSED LOW
OVER THE SRN HIGH PLAINS BY 12Z MONDAY.  MEANWHILE...A STATIC
PATTERN FEATURING A MID-LEVEL ANTICYCLONE OVER THE MID MO VALLEY
WILL BE LOCATED TO THE W OF A SERIES OF DISTURBANCES MAINTAINING A
LARGE-SCALE WSW-ENE ORIENTED TROUGH OVER THE ERN STATES.  A COLD
FRONT WILL ADVANCE SWD ACROSS THE SOUTHEAST STATES AND CENTRAL GULF
COAST STATES.  THE WRN PORTION OF THIS BOUNDARY IS EXPECTED TO
REMAIN QUASI-STATIONARY FROM NRN LA TO THE RED RIVER TO NORTHWEST
TX/NERN NM WHERE A SURFACE LOW WILL BE DEVELOPING.  A NORTH-SOUTH
DRYLINE WILL LIKELY SHARPEN ACROSS PORTIONS OF W-CNTRL AND NW TX
DURING THE DAY.

...SRN PLAINS...
SURFACE MOISTURE...WITH DEW POINTS IN THE UPPER 60S TO LOWER
70S...CURRENTLY RESIDES ACROSS THE TX COASTAL PLAINS INTO
SOUTH-CENTRAL TX.  POLEWARD MOISTENING IS EXPECTED ACROSS THE WARM
SECTOR TODAY AS SLY LOW-LEVEL WINDS INCREASE IN RESPONSE TO HEIGHT
FALLS AHEAD OF THE APPROACHING SWRN STATES TROUGH.  SURFACE DEW
POINTS INTO THE LOWER 60S SHOULD REACH THE RED RIVER VALLEY REGION
BY AFTERNOON...WHILE UPPER 60S REACH THE VICINITY OF WACO TX BY LATE
AFTERNOON.

STRONG HEATING IS FORECAST OVER SWRN TX AND MIDLEVEL LAPSE RATES OF
AT LEAST 8 C/KM WILL LIKELY OVERSPREAD THE WEST EDGE OF THE MOISTURE
RETURN/DRY LINE ACROSS CNTRL TX DURING THE DAY LEADING TO THE
DEVELOPMENT OF A MODERATE TO VERY STRONG INSTABILITY /MLCAPE OF
1500-3000 J PER KG/ ACROSS THE WARM SECTOR.  HEIGHT FALLS WILL
OVERSPREAD W-CNTRL INTO CENTRAL TX AS THE NOSE OF A 70-80-KT H5
SPEED MAX OVER NRN CHIHUAHUA MOVES INTO SW TX BY LATE AFTERNOON.
ISOLD TO WIDELY SCATTERED STORMS SHOULD DEVELOP NEAR THE DRYLINE
THIS AFTERNOON...WITH THE POTENTIAL EXISTING FOR STORMS TO DEVELOP
AS EARLY AS 18-20Z IN CENTRAL TO NORTHERN TX AS SUGGESTED BY THE 00Z
NAM4/NSSL4/NMM4.  VEERING AND STRENGTHENING WINDS WITH HEIGHT WILL
FAVOR SUPERCELLS CAPABLE PRIMARILY OF ISOLATED LARGE TO VERY LARGE
HAIL AND STRONG WINDS.  HOWEVER...AN ISOLATED TORNADO RISK WILL BE
POSSIBLE AS STORMS MOVE E/NEWD INTO RICHER MOISTURE TO THE E OF THE
DRYLINE.  THE POTENTIAL ALSO EXISTS FOR A SECOND ROUND OF STORMS TO
DEVELOP AND MOVE E/NEWD ACROSS PORTIONS OF CENTRAL AND NRN TX WITH
SIMILAR SEVERE WEATHER THREATS.  EACH ROUND OF STORMS SHOULD MOVE
INTO OK WITH HAIL AND DAMAGING WINS BEING THE PRIMARY THREATS AS
ACTIVITY DEVELOPS WITHIN A INCREASING DEEP-LAYER ASCENT PER LOW- TO
MID-LEVEL WAA AND ASCENT WITHIN THE EXIT REGION OF THE SWLY JET
STREAK SPREADING ACROSS THE SRN PLAINS TO THE ARKLATEX.

FARTHER NW...MODELS SHOW AN ELY-COMPONENT AND UPSLOPE FLOW INVOF THE
SWD SAGGING FRONTAL ZONE OVER OK INTO THE TX PANHANDLE.  INCREASING
UPPER-LEVEL FORCING FOR ASCENT COUPLED WITH STRONG HEATING AND
CONVERGENCE ALONG THE ARCING DRYLINE INTO FAR SWRN OK AND THE TX
PANHANDLE WILL PROBABLY ERODE THE CAP BY MID-LATE AFTERNOON.
FORECAST SOUNDINGS SHOW MODERATE BUOYANCY DEVELOPING WITHIN AN AXIS
OF 50S SURFACE DEWPOINTS.  STRONG VEERING WINDS WITH HEIGHT WILL
FAVOR THE DEVELOPMENT OF SUPERCELLS WITH THE MORE ROBUST UPDRAFTS.
COOL MID-LEVEL TEMPS /-16 TO -18 DEG C AT H5/ COULD SUPPORT LARGE TO
VERY LARGE HAIL GROWTH DURING THE MATURE PHASE OF THE STORM LIFE
CYCLE.

...SOUTHEAST STATES...
ASIDE FROM FL...INSTABILITY IS EXPECTED TO BE RATHER WEAK ACROSS
THIS REGION TODAY.  HOWEVER...EFFECTIVE BULK SHEAR WILL BE MORE THAN
SUFFICIENT FOR ORGANIZED STORMS...WITH THE POTENTIAL FOR SUSTAINED
UPDRAFTS DEVELOPING NEAR THE SWD MOVING COLD FRONT.

..PETERS/ROGERS.. 04/26/2015




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