SPC May 26, 2016 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0800 AM CDT THU MAY 26 2016

VALID 261300Z - 271200Z

...THERE IS AN ENH RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
PARTS OF CENTRAL/NRN KS AND SRN NEB...

...THERE IS AN ENH RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
PARTS OF W CENTRAL AND SW TX...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL/SRN PLAINS
THROUGH TONIGHT...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK AND
EXTENDING INTO THE MS VALLEY...

...SUMMARY...
SEVERE THUNDERSTORMS CAPABLE OF TORNADOES AND VERY LARGE HAIL ARE
EXPECTED THURSDAY ACROSS MUCH OF THE SOUTHERN NEBRASKA AND KANSAS
VICINITY.  VERY LARGE HAIL WILL ALSO BE POSSIBLE ACROSS PARTS OF
WEST TEXAS.  ISOLATED LARGE HAIL AND DAMAGING WINDS WILL OTHERWISE
BE POSSIBLE OVER A BROAD AREA OF THE CENTRAL AND SOUTHERN PLAINS.

...CENTRAL/SRN PLAINS THROUGH TONIGHT...
A MIDLEVEL SHORTWAVE TROUGH OVER AZ THIS MORNING WILL PROGRESS EWD
OVER NM TODAY AND REACH THE SRN HIGH PLAINS TONIGHT.  A RELATED LEE
CYCLONE WILL DEEPEN TODAY NEAR THE SW CORNER OF KS...AS A
OUTFLOW-REINFORCED SURFACE FRONT DEVELOPS NWD AS A WARM FRONT FROM
CENTRAL KS TOWARD THE NEB BORDER BY EARLY AFTERNOON.  A VERY MOIST
AIR MASS WITH BOUNDARY LAYER DEWPOINTS IN THE LOW 70S IS PRESENT S
OF THE BOUNDARY AND E OF A DRYLINE THAT ARCS SWWD FROM THE ERN TX
PANHANDLE TO THE W TX/SE NM BORDER.  THIS RICH MOISTURE LIES BENEATH
A PLUME OF NEARLY DRY ADIABATIC MIDLEVEL LAPSE RATES...THE
COMBINATION OF WHICH WILL RESULT IN MLCAPE AOA 4000 J/KG AS SURFACE
HEATING COMMENCES IN THE WARM SECTOR.

THE INITIAL THERMODYNAMIC ENVIRONMENT AND LARGE-SCALE PATTERN APPEAR
QUITE FAVORABLE FOR SEVERE THUNDERSTORMS TODAY ACROSS THE
PLAINS...BUT THERE ARE SOME COMPLICATING FACTORS THAT ARE ALREADY
BECOMING APPARENT THIS MORNING.  CLUSTERS OF THUNDERSTORMS HAVE
FORMED AND CONTINUE TO EXPAND ACROSS CENTRAL TX...WITH MORE ISOLATED
CONVECTION EXTENDING INTO NW TX.  SOME OF THE OVERNIGHT
CONVECTION...ESPECIALLY NEAR SJT...HAS RESULTED IN DOWNWARD
TRANSPORT OF DRY AIR FROM ABOVE THE RELATIVELY SHALLOW MOIST LAYER. 
THE THERMODYNAMIC PROFILE WILL REMAIN FAVORABLE FOR DOWNDRAFT
PRODUCTION WITH MULTICELL CLUSTERS IN AN ENVIRONMENT WITH RELATIVELY
WEAK FLOW/VERTICAL SHEAR IN THE MIDLEVELS...ESPECIALLY FROM N TX
ACROSS OK.

DURING THE AFTERNOON...IT APPEARS THE WARM FRONT IN KS WILL PROVIDE
THE PRIMARY FOCUS FOR THE MORE SIGNIFICANT SEVERE STORM THREAT.  THE
WARM FRONT SHOULD REMAIN LARGELY REMOVED FROM THE STABILIZING
AFFECTS OF THE EARLY TX/OK CONVECTION...THOUGH THERE IS SOME
UNCERTAINTY REGARDING THE TIMING AND MODE OF STORM DEVELOPMENT EVEN
IN KS.  DEEP-LAYER AND LOW-LEVEL SHEAR WILL BE MOST FAVORABLE FOR
SUPERCELLS/TORNADOES NEAR THE WARM BY EARLY AFTERNOON...AND CURRENT
EXPECTATIONS ARE FOR A FEW STORMS TO FORM ALONG THE BOUNDARY BY THIS
TIME.  ADDITIONAL STORM DEVELOPMENT IS EXPECTED ALONG THE DRYLINE
CLOSER TO THE KS/OK BORDER BY MID AFTERNOON...AND THESE STORMS WILL
SPREAD NEWD.  AGAIN...THE TORNADO RISK SHOULD BE GREATER WITH STORMS
INTERACTING WITH THE BOUNDARY...AND DECREASE WITH SWD EXTENT GIVEN
WEAKER VERTICAL SHEAR.

BY LATE AFTERNOON/EVENING...THE SCENARIO WILL CONTINUE TO GET MORE
COMPLEX WITH INCREASINGLY NUMEROUS STORMS AND LIKELY
OUTFLOW/STABILIZING INFLUENCES.  AS SUCH...THE LARGE HAIL AND
TORNADO RISK SHOULD PEAK DURING THE AFTERNOON ALONG THE WARM FRONT
IN KS OR EXTREME SRN NEB...PRIOR TO MORE WIDESPREAD CONVECTIVE
OVERTURNING.  FARTHER S...VERTICAL SHEAR WILL INCREASE BY THIS
EVENING INVOF THE DRYLINE FROM WRN OK TO W TX.  THE LIKELIHOOD OF
RELATIVELY EARLY CONVECTIVE CONTAMINATION...AND WIND PROFILES WITH
PRONOUNCED MIDLEVEL BACKING BOTH CAST DOUBT ON THE MAGNITUDE OF THE
SEVERE RISK FROM NW AND N CENTRAL TX INTO OK.  THE MORE INTENSE
STORMS SHOULD FORM LATER THIS AFTERNOON INTO EARLY TONIGHT ACROSS
PARTS OF W CENTRAL/SW TX...TO THE W-SW OF THE EARLY CENTRAL TX
CONVECTION.  LARGE HAIL...DAMAGING WINDS...AND A FEW TORNADOES WILL
BE POSSIBLE. 

...ERN CO THIS AFTERNOON/EVENING...
AN UPSLOPE FLOW REGIME N OF THE LEE CYCLONE/SURFACE FRONT WILL DRAW
LOW-LEVEL MOISTURE WWD INTO SE AND E CENTRAL CO TODAY BENEATH
LINGERING STEEP MIDLEVEL LAPSE RATES.  SURFACE HEATING AND LIFT
ALONG THE FRONT /IN ADVANCE OF THE APPROACHING MIDLEVEL TROUGH OVER
NM/ WILL SUPPORT THUNDERSTORM DEVELOPMENT AND THE POTENTIAL FOR
SUPERCELLS THIS AFTERNOON.

..THOMPSON/COHEN.. 05/26/2016

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