Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS02 KWNS 251723
SWODY2
SPC AC 251722

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1222 PM CDT FRI JUL 25 2014

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID MS
VALELY...SRN GREAT LAKES AND NRN OH VALLEY...

...SUMMARY...
SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS APPEAR
LIKELY ACROSS PARTS OF THE UPPER MIDWEST...OHIO VALLEY AND SOUTHERN
GREAT LAKES FROM SATURDAY AFTERNOON INTO SATURDAY EVENING.
MARGINALLY SEVERE WIND GUSTS AND HAIL WILL ALSO BE POSSIBLE ACROSS
MUCH OF KANSAS INTO SOUTHERN NEBRASKA AND IN PENNSYLVANIA...SOUTHERN
NEW YORK AND NEW JERSEY SATURDAY AFTERNOON.

...MID MS VALLEY/NRN OH VALLEY/SRN GREAT LAKES...
WEST TO NORTHWEST MID-LEVEL FLOW WILL BE IN PLACE SATURDAY FROM THE
UPPER MS VALLEY EWD INTO THE GREAT LAKES AND OH VALLEY. AT THE
SFC...A COLD FRONT IS FORECAST TO MOVE SEWD INTO THE WRN GREAT LAKES
REGION AND MID TO UPPER MS VALLEY BY AFTERNOON. A LARGE WARM SECTOR
SHOULD EXIST FROM THE MID-MO VALLEY EWD INTO THE SRN GREAT LAKES
WHERE SFC DEWPOINTS SHOULD BE IN THE UPPER 60S TO MID 70S F. AS A
RESULT...MODEL FORECASTS DEVELOP MODERATE TO STRONG INSTABILITY
ACROSS THE SLIGHT RISK AREA DURING THE DAY WITH STORMS INITIATING
AHEAD OF THE FRONT IN THE MID-MO VALLEY AROUND MIDDAY. CONVECTIVE
COVERAGE IS FORECAST TO EXPAND EWD ACROSS SRN IA...NRN MO...IL AND
IND DURING THE AFTERNOON AS A MCS DEVELOPS ALONG THE INSTABILITY
AXIS. A PERSISTENT AND ORGANIZED LINE-SEGMENT MAY DEVELOP AND MOVE
EWD ACROSS THE NRN OH VALLEY DURING THE LATE AFTERNOON AND EARLY
EVENING.

NAM FORECAST SOUNDINGS ALONG THE INSTABILITY AXIS FOR DAVENPORT IA
AND INDIANAPOLIS IND AT 21Z/SAT SHOW IMPRESSIVE THERMODYNAMICS WITH
MLCAPE ABOVE 2500 J/KG AND VERY STEEP LAPSE RATES. IN ADDITION...THE
WIND PROFILE HAS DIRECTIONAL SHEAR BELOW 850 MB WITH SUBSTANTIAL
SPEED SHEAR IN THE MID-LEVELS RESULTING IN 40 TO 50 KT OF 0-6 KM
SHEAR. THIS ENVIRONMENT SHOULD BE FAVORABLE FOR A SEVERE PRODUCING
MCS WITH WIDESPREAD WIND DAMAGE POSSIBLE. IF THE LOWER TO MID 70S F
DEWPOINTS MATERIALIZE ACROSS MUCH OF THE SLIGHT RISK AREA BY
SATURDAY AFTERNOON...THEN AN UPGRADE TO MODERATE RISK ACROSS PARTS
OF THE MID MS VALLEY AND NRN OH VALLEY MAY BE NECESSARY. MODEL
SOLUTIONS STILL DIFFER MARKEDLY ON THE MAGNITUDE OF THE SEVERE
THREAT SATURDAY AFTERNOON AND UNCERTAINTY IS STILL SIGNIFICANT
CONCERNING THE DAY 2 FORECAST.

...KS/SRN NEB...
WEST TO NORTHWEST FLOW WILL BE IN PLACE ACROSS THE CNTRL AND NRN
PLAINS SATURDAY AS A COLD FRONT MOVES SWD THROUGH THE CNTRL PLAINS.
AHEAD OF THE FRONT...SFC DEWPOINTS SHOULD BE IN THE MID TO UPPER 60S
F RESULTING IN THE DEVELOPMENT OF MODERATE INSTABILITY BY AFTERNOON.
THUNDERSTORM INITIATION APPEARS PROBABLE ALONG THE FRONT BY
MID-AFTERNOON FROM SRN NEB SWD ACROSS MUCH OF KS. FORECAST SOUNDINGS
IN CNTRL AND WRN KS SHOW MLCAPE ABOVE 2000 J/KG WITH ABOUT 30 KT OF
0-6 KM SHEAR. THIS COMBINED WITH VERY STEEP LAPSE RATES AND HIGH
TEMP-DEWPOINT SPREADS MAY BE ENOUGH FOR MARGINALLY SEVERE WIND GUSTS
ASSOCIATED WITH HIGH BASED STORMS.

...SRN NY/PA/NJ...
A SUBTLE SHORTWAVE TROUGH IS FORECAST TO MOVE ACROSS THE CNTRL AND
NRN APPALACHIAN MTNS DURING THE DAY ON SATURDAY. AT THE SFC...WINDS
WILL BE SOUTH SOUTHWESTERLY ACROSS MUCH OF THE ERN SEABOARD WHERE A
CORRIDOR OF LOW-LEVEL MOISTURE WILL BE IN PLACE. SFC DEWPOINTS IN
THE MID TO UPPER 60S F SHOULD RESULT IN THE DEVELOPMENT OF MODERATE
INSTABILITY FROM VA EXTENDING NWD INTO CNTRL AND ERN PA. ALTHOUGH
SUBSIDENCE MAY EXIST JUST BEHIND THE SHORTWAVE TROUGH SATURDAY
AFTERNOON...ISOLATED THUNDERSTORMS MAY BE ABLE TO INITIATE ACROSS
PARTS OF THE MID-ATLANTIC AND CNTRL APPALACHIAN MTNS AS SFC TEMPS
PEAK IN THE AFTERNOON. THE MODERATE INSTABILITY COMBINED WITH STEEP
LOW-LEVEL LAPSE RATES MAY BE ENOUGH FOR MARGINALLY SEVERE WIND
GUSTS.

..BROYLES.. 07/25/2014



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