Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 310601
SWODY1
SPC AC 310600

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT TUE MAY 31 2016

VALID 311200Z - 011200Z

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE SRN PLAINS THROUGH THE
MS VALLEY AND GULF COAST REGION...

...SUMMARY...
ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON
INTO EARLY EVENING FROM THE UPPER MISSISSIPPI VALLEY SOUTHWESTWARD
INTO THE SOUTHERN GREAT PLAINS. A FEW STRONG THUNDERSTORMS ARE
POSSIBLE FROM THE LOWER MISSISSIPPI VALLEY INTO THE GULF COAST
REGION. DAMAGING WIND GUSTS AND HAIL ARE THE PRIMARY THREATS.

...SYNOPSIS...

THE SYNOPTIC PATTERN WILL REMAIN DOMINATED BY A COMPLEX SPLIT-FLOW
REGIME TODAY. IN THE NRN STREAM...A SHORTWAVE TROUGH CURRENTLY OVER
THE NRN PLAINS WILL MOVE SLOWLY EWD...REACHING THE UPPER MS VALLEY
THIS EVENING. WEAKER SRN-STREAM UPPER TROUGH OVER SRN AZ WILL DRIFT
VERY SLOWLY EWD INTO NWRN MEXICO. SFC LOW ASSOCIATED WITH THE
NRN-STREAM TROUGH WILL OCCLUDE OVER ND WITH TRAILING COLD FRONT
CONTINUING THROUGH THE UPPER MS VALLEY AND CNTRL PLAINS. THE SWRN
EXTENSION OF THIS BOUNDARY WILL MOVE INTO THE TX PANHANDLE DURING
THE DAY.

...SRN PLAINS...

MOIST WARM SECTOR WITH LOW 70S F DEWPOINTS WILL PERSIST OVER SRN AND
CNTRL TX...AND DEWPOINTS NEAR 70 WILL ADVECT THROUGH THE ERN HALF OF
TX WITH LOW 60S FARTHER WEST INTO WRN TX. SEVERAL MCVS...NUMEROUS
OUTFLOW BOUNDARIES AND CONVECTIVE DEBRIS EXIST ACROSS WRN TX...AND
ONGOING STORMS OVER NRN MEXICO THROUGH FAR WRN TX APPEAR TO BE
ASSOCIATED WITH A WEAK SRN-STREAM IMPULSE. POTENTIAL WILL EXIST FOR
THE ATMOSPHERE TO ONCE AGAIN BECOME MODERATELY TO STRONGLY UNSTABLE
OVER WRN AND SWRN TX WHERE STEEP MID-LEVEL LAPSE RATES WILL EXIST AS
WELL AS FARTHER EAST THROUGH CNTRL AND SRN TX WHERE RICH LOW LEVEL
MOISTURE RESIDES. MODERATE INSTABILITY IS ALSO LIKELY NWD INTO OK.
SEVERAL MECHANISMS FOR THUNDERSTORM INITIATION WILL EXIST INCLUDING
ALONG THE SWD-ADVANCING COLD FRONT/OUTFLOW BOUNDARY IN OK AND THE TX
PANHANDLE...THE HIGHER TERRAIN OF WRN TX AND ERN NM...AND ALONG ANY
RESIDUAL OUTFLOW BOUNDARIES OVER WRN TX. EFFECTIVE BULK SHEAR OVER
MUCH OF THIS REGION WILL REMAIN WEAK...BUT WITH SOMEWHAT STRONGER
VERTICAL SHEAR OVER SWRN AND SRN TX WHERE A BELT OF SLIGHTLY
STRONGER WINDS RESIDES. THUNDERSTORMS WILL LIKELY REDEVELOP IN THESE
REGIONS DURING THE AFTERNOON...AND SOME OF THE STORMS MAY POSE A
RISK FOR A FEW DAMAGING WIND GUSTS AND LARGE HAIL.

GIVEN COMPLEXITIES ASSOCIATED WITH ONGOING
CONVECTION...UNCERTAINTIES WHERE GREATEST CONCENTRATION OF STORMS
WILL OCCUR COINCIDENT WITH BEST DESTABILIZATION POTENTIAL...ALONG
WITH THE MODEST SHEAR ENVIRONMENT...WILL MAINTAIN MARGINAL RISK THIS
UPDATE. HOWEVER...A SLIGHT RISK MAY BE NEEDED FOR PORTIONS OF THIS
REGION IN LATER OUTLOOKS ONCE MESOSCALE DETAILS BECOME MORE CLEAR.

...UPPER MS VALLEY REGION...

ONGOING STORMS WILL LIKELY CONTINUE TO WEAKEN THROUGH EARLY TODAY.
THUNDERSTORMS ARE EXPECTED TO REDEVELOP ALONG RESIDUAL OUTFLOW
BOUNDARY THIS AFTERNOON AS THE BOUNDARY LAYER DESTABILIZES. A FEW
STORMS MIGHT PRODUCE A FEW STRONG WIND GUSTS. HOWEVER...WEAK
VERTICAL SHEAR AND MODEST INSTABILITY SUGGEST OVERALL SEVERE THREAT
SHOULD REMAIN LIMITED.

...LOWER MS VALLEY THROUGH GULF COAST REGION...

STORMS ARE EXPECTED TO REDEVELOP ALONG RESIDUAL BOUNDARIES FROM THE
LOWER MS VALLEY INTO GULF COAST REGION AS THE ATMOSPHERE BECOMES
MODERATELY UNSTABLE. MULTICELL STORMS CAPABLE OF A FEW WET
MICROBURSTS WILL BE THE MAIN THREAT.

..DIAL/DEAN.. 05/31/2016

$$



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