Severe Thunderstorm Warning 129, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
628 PM CDT THU JUL 16 2015

.UPDATE...
ISSUED AT 623 PM CDT THU JUL 16 2015

ISOLATED STORMS HAVE DEVELOPED IN NORTHEAST NEBRASKA LATE THIS
AFTERNOON...WITHIN AN ENVIRONMENT CHARACTERIZED BY 30-35 KNOTS OF
EFFECT BULK SHEAR AND AROUND 4000 J/KG. FREEZING LEVEL REMAINS
QUITE HIGH...BUT THE STORMS HAVE SHOWN WEAK ROTATION AND COULD BE
CAPABLE OF SOME PENNY TO NICKEL SIZE HAIL. MAINTAINED ISOLATED
WORDING IN NORTHEAST NEBRASKA AND NORTHWEST IOWA FOR A COUPLE OF
HOURS THIS EVENING.

&&

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 254 PM CDT THU JUL 16 2015

FIRST OFF...HAVE DECIDED TO ISSUE A HEAT ADVISORY OVER PORTIONS
OF THE SRN CWA WHERE HEAT INDICES OF 105 TO 110 ARE EXPECTED FRIDAY
AND SATURDAY AFTN.

WESTERLIES WILL BE SITUATED ACROSS THE NRN TIER STATE THE NEXT
SEVERAL DAYS WITH THE MAIN FEATURE OF INTEREST BEING A POTENT VORT
MAX PROGGED TO TREK EWD ALONG THE U.S./CAN OVER THE WEEKEND.
INCREASING DPVA SPREADING OVER THE NRN PLAINS EVENTUALLY INDUCES
SFC CYCLOGENESIS WITH ATTENDANT COLD FRONT EXTENDING FROM THE
UPPER MIDWEST TO WRN KS BY 12Z SAT. NAM AND GFS ADVERTISE STOUT
MOISTURE POOLING IS PROGGED AT THAT TIME ALONG THE BNDRY RESULTING
FROM LLVL THETA-E ADVECTION WITH PWS VALUES AROUND 2" INCHES.
HOWEVER...WITH MODELS DIFFERING WHERE MAX OMEGA/HIGHEST
ENVIRONMENTAL MOISTURE CONTENT WILL BE FOUND...PINNING DOWN POP
PLACEMENT SOMEWHAT PROBLEMATIC. AS OF NOW THE GFS AND CMC ARE
SIMILAR LAYING QPF ACROSS THE CWA FRIDAY NIGHT WITH THE NAM
FOCUSING PCPN ACTIVITY MAINLY OVER ERN SD. ON THE OTHER HAND THE
ECM AND SREF IS FOCUSING BEST LIFT/MOISTURE MAINLY OVER THE UPPER
MIDWEST. AND AT THIS POINT LATEST HPC PCPN GRAPHICS ARE SUGGESTING
THEY ARE FAVORING THE ECM/SREF SOLUTIONS.

REGARDING SVR POTENTIAL...COMBINATION OF DAYTIME HEATING/MOISTURE
RICH ENVIRONMENT WILL RESULT IN EXTREMELY UNSTABLE CONDITIONS BY
FRIDAY AFTN WITH 0-3KM CAPE RANGING FROM 4000-5000J/KG. IN ADDITION
TO THAT EFFECTIVE SHEAR IS PROGGED TO INCREASE TO 50-60KT...THUS
MAKING CONDITIONS RATHER FAVORABLE FOR SUPERCELL DEVELOPMENT.
HOWEVER...DID NOTICE BOTH THE NAM/GFS INDICATE 0-6KM DEEP LYR SHEAR
WILL BE SOMEWHAT MARGINAL HEADING INTO FRIDAY EVENING.

SAT/SAT NIGHT/SUN...MODELS IN AGREEMENT MAINTAINING MID LYR
AGEOSTROPHIC LIFT/BNDRY LYR THETA-E CONVG ALONG THE SLOW MOVING
SWD BOUND SFC FRONT. ENVIRONMENT WILL STILL BE MOISTURE RICH AHEAD
OF THE BNDRY WITH PWS VALUES STILL IN THE 2" RANGE.

OTHERWISE...A NOTICEABLE COOL DOWN IS ON TAP SUNDAY OVER THE REGION
WITH NAM12/ECM/GMOS25 IN VERY GOOD AGREEMENT ADVERTISING AFTN HIGHS
IN THE LOW/MID 80S.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 254 PM CDT THU JUL 16 2015

GFS/ECM SIMILAR SHOWING NEAR ZONAL FLOW EARLY ON WITH BEFORE A VERY
SUBTLE/LOW AMPLITUDE UPPER RIDE BECOMES SITUATED OVER THE CONUS.
MEX/ECMMOS METEOGRAMS INDICATE MAX TEMPS WILL PRETTY MUCH HOVER
AROUND NORMAL THROUGHOUT THE EXT PD. REGARDING PCPN...SUNDAY/SUNDAY
NIGHT POPS ARE AN EXTENSION ASSOCIATED WITH EXITING SFC FRONT.
OTHERWISE GOING FCST HAS TOKEN POPS MONDAY NIGHT THROUGH WEDNESDAY
NIGHT. NOT VERY IMPRESSED PCPN POTENTIAL...BUT WILL OPT TO LEAVE IN
PLACE TO AVOID FLIP-FLOPPING.

&&

.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 623 PM CDT THU JUL 16 2015

GENERALLY VFR CONDITIONS THROUGH THE PERIOD...ALTHOUGH TEMPORARY
MVFR FOG MAY DEVELOP TONIGHT 11-14Z AT KOFK/KOMA. ISOLATED
THUNDERSTORMS HAD ALSO DEVELOPED IN NORTHEAST NEBRASKA NEAR KOFK.
WHILE IT APPEARS THESE WILL PROBABLY NOT IMPACT THAT LOCATION
DIRECTLY...THEY WILL BE IN THE KOFK VICINITY FOR ABOUT AN HOUR.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...HEAT ADVISORY FROM 2 PM TO 8 PM CDT FRIDAY FOR NEZ052-053-067-
     068-089>093.

     HEAT ADVISORY FROM 2 PM TO 8 PM CDT SATURDAY FOR NEZ052-053-067-
     068-089>093.

IA...HEAT ADVISORY FROM 2 PM TO 8 PM CDT FRIDAY FOR IAZ069-079-080-
     090-091.

     HEAT ADVISORY FROM 2 PM TO 8 PM CDT SATURDAY FOR IAZ069-079-080-
     090-091.

&&

UPDATE...DEWALD
SHORT TERM...DEE
LONG TERM...DEE
AVIATION...DEWALD