Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 300504
SWODY1
SPC AC 300502

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1202 AM CDT SAT MAY 30 2015

VALID 301200Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER  A PORTION OF WRN MAINE...

...THERE IS A MRGL RISK OF SVR TSTMS FROM A PORTION OF TX THROUGH
THE TN AND OH VALLEYS INTO THE NERN STATES...

...THERE IS A MRGL RISK OF SVR TSTMS OVER A PORTION OF WRN AND CNTRL
MT...

...SUMMARY...
SCATTERED THUNDERSTORMS...SOME STRONG TO POSSIBLY SEVERE WITH GUSTY
WINDS AND HAIL...WILL DEVELOP NEAR AND AHEAD OF A COLD FRONT FROM
PARTS OF THE NORTHEAST STATES AND MIDWEST TO TEXAS ON SATURDAY.
ADDITIONALLY...A FEW STRONG TO POSSIBLY SEVERE STORMS ARE EXPECTED
ACROSS PARTS OF NEW MEXICO...AND IN CENTRAL AND EASTERN MONTANA
SATURDAY AFTERNOON AND EVENING.

...SYNOPSIS...

WEAK FLOW REGIME WILL PERSIST OVER THE U.S. SATURDAY. UPPER TROUGH
NOW OVER ONTARIO WILL MOVE THROUGH QUEBEC AND REACH NRN MAINE LATE
SATURDAY NIGHT. A CONVECTIVELY ENHANCED VORTICITY MAXIMUM THAT IS
NOW OVER THE ARKLATEX REGION WILL WEAKEN AS IT SHEARS NEWD THROUGH
THE TN AND OH VALLEYS. OTHER VORTICITY MAXIMA WILL MOVE THROUGH THE
CNTRL U.S. AND MID MS VALLEY. AT THE SFC A COLD FRONT SHOULD EXTEND
FROM THE GREAT LAKES SWD THROUGH THE MID MS VALLEY INTO SWRN TX. BY
THE END OF THE PERIOD THIS BOUNDARY IS FORECAST TO EXTEND FROM FAR
EAST MAINE SWWD THROUGH SRN TX.

...MAINE...

STRENGTHENING SWLY LLJ WILL ADVECT LOW 60S DEWPOINTS THROUGH THE
PRE-FRONTAL WARM SECTOR. STRONG DIABATIC WARMING WILL FURTHER
DESTABILIZE THE ATMOSPHERE...BUT MLCAPE SHOULD REMAIN AOB 1000 J/KG
DUE TO WEAK MID-LEVEL LAPSE RATES. THUNDERSTORMS ARE EXPECTED TO
DEVELOP ALONG AND JUST AHEAD OF SEWD ADVANCING FRONT...LIKELY
AFFECTING WESTERN MAINE BY LATE AFTERNOON OR EVENING. FLOW ALOFT
WILL STRENGTHEN IN ASSOCIATION WITH THE APPROACHING UPPER TROUGH
WITH SWLY WINDS FROM 40-50 KT BETWEEN 800-500 MB. STORMS MOTIONS
FROM 40-45 KT AND INVERTED-V BOUNDARY LAYERS WILL PROMOTE A THREAT
OF A FEW STRONG TO DAMAGING WIND GUSTS UNTIL AROUND MID-EVENING WHEN
STORMS SHOULD WEAKEN DUE TO ONSET OF NOCTURNAL COOLING.

...CNTRL THROUGH SRN TX...

MCV WILL CONTINUE ESEWD THROUGH CNTRL AND SERN TX DURING THE DAY.
STORMS SHOULD BE ONGOING FROM PARTS OF NRN THROUGH SWRN TX IN
ASSOCIATION WITH THIS FEATURE. STORMS MAY RE-INTENSIFY AS THEY
DEVELOP SEWD THROUGH THE DESTABILIZING WARM SECTOR WHERE MLCAPE
COULD APPROACH 2500-3000 J/KG. WIND PROFILES WILL REMAIN WEAK IN
GENERAL...BUT SOME ENHANCEMENT TO THE VERTICAL SHEAR MIGHT OCCUR IN
VICINITY OF THE MCV. STORMS MAY BECOME CAPABLE OF PRODUCING ISOLATED
DAMAGING WIND AND HAIL DURING THE AFTERNOON.

...TN AND OH VALLEY AREA...

STORMS ARE EXPECTED TO REDEVELOP IN ASSOCIATION WITH ENEWD MOVING
MCV AND ANY ATTENDANT OUTFLOW BOUNDARIES. SFC HEATING WILL
DESTABILIZE THE MOIST BOUNDARY LAYER...BUT WEAK MID-LEVEL LAPSE
RATES SHOULD LIMIT MLCAPE TO AROUND 1500 J/KG. THOUGH AMBIENT
VERTICAL SHEAR WILL REMAIN WEAK...SOME ENHANCEMENT TO THE WIND
PROFILES MAY REMAIN IN VICINITY OF THE VORTICITY MAXIMUM...AND A FEW
STORMS COULD ATTAIN AT LEAST WEAK UPDRAFT ROTATION WITHIN AN
ENVIRONMENT OTHERWISE FAVORABLE FOR MULTICELLS. SOME STORMS COULD
PRODUCE ISOLATED STRONG TO DAMAGING GUSTS BEFORE WEAKENING WITH
ONSET OF NOCTURNAL COOLING.

...WRN THROUGH CNTRL MT...

LOW-AMPLITUDE SHORTWAVE TROUGH WILL MOVE EASTWARD NEAR THE CREST OF
THE CENTRAL/SOUTHERN ROCKIES UPPER RIDGE. A FEW STORMS SHOULD FORM
OVER THE MOUNTAINS OF WRN MT DURING THE AFTERNOON AND SUBSEQUENTLY
DEVELOP EASTWARD INTO PORTIONS OF CENTRAL/EASTERN MT THROUGH THE
LATE AFTERNOON AND EVENING. INVERTED-V BOUNDARY LAYERS MAY ALLOW FOR
SOME STRONGER/POSSIBLY SEVERE THUNDERSTORMS CAPABLE OF DOWNBURST
WINDS.

..DIAL/COOK.. 05/30/2015




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