Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 111727
SWODY2
SPC AC 111726

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT FRI JUL 11 2014

VALID 121200Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN NEB TO SRN WI AND A
PORTION OF THE SRN GREAT LAKES...

...SUMMARY...
STRONG TO SEVERE THUNDERSTORMS ARE FORECAST TO DEVELOP FROM PORTIONS
OF THE CENTRAL PLAINS TO SOUTHERN WISCONSIN AND A PORTION OF THE
SOUTHERN GREAT LAKES ON SATURDAY. MORE SCATTERED STRONG TO SEVERE
STORMS MAY ALSO DEVELOP FROM THE NORTHERN ROCKIES TO THE CENTRAL
HIGH PLAINS.

...SYNOPSIS...
STRONG UPPER RIDGE CENTERED OVER THE SRN HIGH PLAINS TODAY WILL
SHIFT WWD INTO THE SWRN STATES AND GREAT BASIN ON SATURDAY.  THIS
WILL OCCUR AS A SHORTWAVE TROUGH...CURRENTLY APPROACHING NRN
ALBERTA/SASKATCHEWAN FROM THE NORTHWEST TERRITORIES...DIGS SEWD
THROUGH THE WRN TO SRN PERIPHERIES OF A CLOSED LOW CENTERED OVER NRN
MANITOBA.  ALTHOUGH THERE WILL BE WEAK HEIGHT FALLS WITH THE
CANADIAN SYSTEM DURING THE FIRST-HALF OF DAY 2...A SHORTWAVE TROUGH
/CURRENTLY LOCATED OVER UT/...IS EXPECTED TO TRACK EWD FROM SD
ACROSS THE SLIGHT RISK AREA SATURDAY AFTERNOON AIDING IN TSTM
DEVELOPMENT.

...ERN NEB/IA/FAR NRN MO TO SRN WI AND SRN GREAT LAKES REGION...
A WEAK FRONTAL ZONE STRETCHING FROM SRN NEB THROUGH IA TO SRN WI IS
EXPECTED TO BE MODULATED SOME BY ONGOING TSTMS AT THE START OF DAY 2
WITH THE SRN PERIPHERY OF THIS ACTIVITY BEING A DIFFERENTIAL HEATING
BOUNDARY INTO SATURDAY AFTERNOON.  MEANWHILE...A COLD FRONT
STRETCHING FROM NRN WI THROUGH CENTRAL MN TO SRN SD AT 12Z SATURDAY
IS EXPECTED TO ADVANCE S/SEWD AND MERGE/OVERTAKE THE WEAKER FRONTAL
ZONE.  THE COLD FRONT SHOULD EXTEND FROM SWRN ONTARIO THROUGH NRN
IND/IL/MO TO SRN KS AND THE TX PANHANDLE BY 12Z SUNDAY.  THESE
BOUNDARIES WILL BE THE FOCUS FOR TSTM DEVELOPMENT ON DAY 2.

VERY RICH MOISTURE WILL RESIDE INVOF THESE BOUNDARIES WITH PW VALUES
OF 1.75-2 INCHES.  SURFACE HEATING...EXPECTED TO BE STRONGEST SOUTH
OF THE WEAK FRONT/DIFFERENTIAL HEATING BOUNDARY...COMBINED WITH THE
MOIST AIR MASS WILL RESULT IN MODERATE-STRONG INSTABILITY /2500-3500
J PER KG/.  FORCING FOR ASCENT ATTENDANT TO THE UT SHORTWAVE TROUGH
AND WAA WITHIN THE NOSE OF A CENTRAL PLAINS LLJ EXTENDING INTO THE
SLIGHT RISK AREA WILL SUPPORT TSTM DEVELOPMENT INTO SATURDAY
AFTERNOON/EVENING.  EFFECTIVE BULK SHEAR OF 35-55 KT...GIVEN
STRENGTHENING WLY MIDLEVEL WINDS ATTENDANT TO THE UT TROUGH AND
AMPLIFYING CANADIAN TROUGH...WILL SUPPORT BOTH BOWING LINE SEGMENTS
AND SUPERCELLS.  ALL SEVERE HAZARDS ARE POSSIBLE...WITH DAMAGING
WINDS BECOMING A GREATER THREAT SATURDAY NIGHT WITH ANY UPSCALE
GROWTH INTO AN MCS.  SOME OF THESE STORMS MAY PERSIST EAST INTO
LOWER MI AND PARTS OF NORTHWEST OH LATE INTO SATURDAY NIGHT...GIVEN
THE INCREASE IN FORCING AND ASCENT AS THE CANADIAN UPPER TROUGH
UNDERGOES STRONGER AMPLIFICATION.

...NERN ND/FAR NWRN MN...
TSTMS SHOULD DEVELOP AND/OR MOVE SSEWD ALONG A COLD FRONT ATTENDANT
TO THE CANADIAN SHORTWAVE TROUGH AS THIS SYSTEM MOVES INTO NERN
ND/NWRN MN SATURDAY EVENING.  ALTHOUGH DEEP LAYER SHEAR WILL BE
SUFFICIENT FOR STORM ORGANIZATION...WEAKER INSTABILITY SHOULD LIMIT
THE COVERAGE OF THE SEVERE WEATHER THREAT.

...NORTHERN ROCKIES TO CENTRAL HIGH PLAINS...
STORMS WILL LIKELY DEVELOP OVER THE HIGHER TERRAIN AND SPREAD EAST
INTO THE CENTRAL HIGH PLAINS ALONG AND NORTH OF THE WEAK BOUNDARY
FROM KS TO NEB. VERTICAL SHEAR AND FORCING WILL BE SOMEWHAT WEAKER
OVER THESE AREAS. HOWEVER...STEEP LAPSE RATES AND MODERATE
INSTABILITY WILL SUPPORT A CHANCE FOR ISOLATED STRONG WIND GUSTS AND
HAIL THROUGH EARLY SAT EVENING.

..PETERS.. 07/11/2014



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