Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 281655
SWODY2
SPC AC 281655

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1155 AM CDT THU MAY 28 2015

VALID 291200Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF WEST TX AND THE
TX PANHANDLE...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...ARKLATEX...OZARKS...MID-MO VALLEY...MID TO UPPER MS VALLEY
AND GREAT LAKES REGION...

...SUMMARY...
SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS PARTS OF THE
SOUTHERN HIGH PLAINS ON FRIDAY WHERE LARGE HAIL AND WIND DAMAGE WILL
BE POSSIBLE. SCATTERED STRONG THUNDERSTORMS WITH HAIL AND MARGINALLY
SEVERE WIND GUSTS ARE EXPECTED TO DEVELOP AHEAD OF A COLD FRONT FROM
THE GREAT LAKES SOUTHWESTWARD ACROSS THE MID MISSOURI VALLEY INTO
THE CENTRAL PLAINS.

...SRN AND CNTRL HIGH PLAINS...
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE SRN AND
CNTRL PLAINS ON FRIDAY AS A COLD FRONT ADVANCES SEWD INTO CNTRL KS
AND THE OK PANHANDLE. AHEAD OF THE BOUNDARY...SFC DEWPOINTS IN THE
MID TO UPPER 60S F SHOULD ENABLE MODERATE TO STRONG INSTABILITY TO
DEVELOP. THE STRONGEST INSTABILITY IS FORECAST OVER THE TX PANHANDLE
AND WEST TX WHERE LAPSE RATES WILL BE STEEPEST. THUNDERSTORMS APPEAR
LIKELY TO INITIATE ALONG THE FRONT DURING THE AFTERNOON WITH A
SEVERE THREAT DEVELOPING IN THE SRN HIGH PLAINS. SEVERAL CLUSTERS OF
STRONG TO SEVERE STORMS SHOULD SPREAD SEWD ACROSS THE SLIGHT RISK
AREA DURING THE LATE AFTERNOON AND EARLY EVENING.

FORECAST SOUNDINGS AT 00Z/SAT FOR AMARILLO AND LUBBOCK SHOW
IMPRESSIVE THERMODYNAMICS WITH MLCAPE OF 2500 TO 3500 J/KG AND 850
TO 500 MB LAPSE RATES AROUND 8.0 C/KM. THIS COMBINED WITH MODERATE
DEEP-LAYER SHEAR SHOULD BE FAVORABLE FOR SUPERCELLS WITH LARGE HAIL.
THE CURRENT THINKING IS THAT SUPERCELLS WILL BE MOST LIKELY IN THE
FIRST COUPLE HOURS OF THE EVENT BEFORE A TRANSITION TO LINEAR MODE
OCCURS. WIND DAMAGE WILL ALSO BE POSSIBLE ESPECIALLY IF A PERSISTENT
LINE SEGMENT CAN ORGANIZE. ALTHOUGH AN ISOLATED SEVERE THREAT COULD
ALSO DEVELOP ACROSS PARTS OF CNTRL AND ERN TX...OK AND KS...WEAKER
DEEP-LAYER SHEAR IS FORECAST IN THESE AREAS SUGGESTING ANY SEVERE
THREAT SHOULD REMAIN MARGINAL THERE.

...MID MO VALLEY/MID TO UPPER MS VALLEY/GREAT LAKES...
SOUTHWEST FLOW ALOFT WILL BE IN PLACE FROM THE MID MO VALLEY NEWD
ACROSS THE MID TO UPPER MS VALLEY INTO THE GREAT LAKES REGION ON
FRIDAY. AT THE SFC...A COLD FRONT IS FORECAST TO ADVANCE SEWD ACROSS
WI...SE MN AND NRN IA DURING THE AFTERNOON. AHEAD OF THE
BOUNDARY...SFC DEWPOINTS IN THE MID TO UPPER 60S F SHOULD ENABLE THE
DEVELOPMENT OF MODERATE INSTABILITY FROM THE MID MO VALLEY NEWD INTO
THE GREAT LAKES AROUND MIDDAY. MODEL FORECASTS SUGGEST THAT
SCATTERED THUNDERSTORMS WILL DEVELOP SPORADICALLY ALONG THIS
CORRIDOR DURING THE AFTERNOON. NAM FORECAST SOUNDINGS FOR DES
MOINES...CHICAGO AND DETROIT AT 21Z SHOW MLCAPE FROM 1000 TO 2000
J/KG WITH STEEP LAPSE RATES IN THE LOW-LEVELS. WIND PROFILES ARE
UNIDIRECTIONAL WITH SOME SPEED SHEAR IN THE MID-LEVELS. THIS MAY BE
ENOUGH FOR A MARGINAL WIND DAMAGE THREAT WITH THE MORE PERSISTENT
MULTICELL CLUSTERS.

..BROYLES.. 05/28/2015




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