Severe Thunderstorm Warning 66, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
615 PM CDT SUN MAY 26 2013

.AVIATION...

00Z TAFS FOR KOMA...KLNK...KOFK.

UNCERTAINTY IN REGARDS TO TSRA IS THE PRIMARY AVIATION FORECAST
ISSUE.

IFR CEILINGS CONTINUED ALL DAY AT KOFK BUT MAY LIFT A BIT YET THIS
EVENING...BEFORE GOING DOWN AGAIN OVERNIGHT. VFR CONDITIONS ARE
LIKELY TO OCCUR AT KOMA AND KLNK THROUGH THE EVENING...THEN DROP
AFTER 06Z. MODELS ARE QUITE VARIABLE WITH TSRA DEVELOPMENT...AND
TENDED TO JUST HAVE A PROB30 GROUP FOR KOMA AND KLNK AFTER 09Z.
WILL AMEND TAFS IF STORMS DEVELOP BEFORE THAT. TSRA COULD AFFECT
KOFK A BIT EARLIER...BY AROUND OR BEFORE 05Z. WILL MONITOR THINGS
THROUGH THE EVENING TO SEE IF CONVECTIVE TRENDS BECOME MORE CLEAR.

CEILINGS AND VSBYS SHOULD IMPROVE LATE MORNING OR EARLY AFTERNOON
MONDAY...ESPECIALLY AT KOMA AND KLNK.

MILLER

&&

.PREV DISCUSSION... /ISSUED 249 PM CDT SUN MAY 26 2013/

DISCUSSION...

VERY ACTIVE WEEK ON TAP OVER THE CNTRL PLAINS WITH POTENTIAL SVR
ACTIVITY ALONG WITH PROLONGED/EXCESSIVE PCPN. MORNING PRECIP WATER
PLOTS WERE SHOWING AMPLE GULF MOISTURE IN PLACE WITH VALUES ROUGHLY
150% OF NORM. LATEST MESOSCALE ANALYSIS INDICATING STOUT MOISTURE
STILL STREAMING INTO THE REGION...AND MODELS ARE IN GOOD AGREEMENT
THIS INFLUX OF MOISTURE WILL CONTINUE THRU AT LEAST
MIDWEEK...GUARANTEEING ENVIRONMENTAL MOISTURE CONTENT WILL REMAIN
QUITE HIGH. AS A MATTER OF FACT...THE GFS IS SUGGESTING TOTAL PCPN
AMOUNTS REACHING 400% OF NORM OVER IA BY NEXT SUNDAY GIVEN SUSTAINED
PCPN EFFICIENCY.

MEANWHILE...MODELS ARE AGAIN IN GOOD AGREEMENT LARGE SCALE FLOW THRU
THIS WEEK WILL GRADUALLY TRANSITION FROM A LARGE CLOSED LOW
CURRENTLY SITTING OVER THE PAC NW TO A RATHER IMPRESSIVE DEEP
ELONGATED LONGWAVE TROF WITH THE AXIS EXTENDING FROM THE ALASKAN
GULF TO THE SRN TIP OF TX. HEADING INTO NEXT WEEKEND THEN...MODELS
PROG THE WRN CONUS TROF BECOMING MORE BROAD IN NATURE WITH LITTLE
MOVEMENT.

FOR TONIGHT...STOUT 310K ISENTROPIC UPGLIDE IS THE DRIVING FORCE FOR
CONVECTIVE ACTIVITY. LIFT WILL BE FURTHER ENHANCED VIA UPPER DIVG
ASSOCIATED WITH RRQ OF JET MAX. MODELS ADVERTISE ENVIRONMENTAL
INSTABILITY WILL REMAIN HIGH OVERNIGHT WITH THE AXIS FOCUSED WEST OF
THE CWA WITHIN AREA OF BEST DEEP LYR SHEAR/MUCAPES. LATEST HRRR
INITIATES CONVECTION THIS EVEN INVOF THE INSTABILITY AXIS...THEN
GRADUALLY PUSHES IT EWD OVERNIGHT. AT THIS POINT CANNOT DISCOUNT A
FEW STORMS PRODUCING HAIL AND/OR STRONG WIND GUSTS.

AS FOR SVR POTENTIAL...SPC CONVECTIVE OUTLOOK KEEPS THE CWA IN THE
SLGT RISK THRU DAY 3.  LOOKING AT MONDAY AFTN/EVENING...FAVORABLE
CONDITIONS APPEAR TO BE FOCUS INVOF THE SRN CWA ALONG A WARM FRONT
EXTENDING ALONG THE NEB/KS BORDER. COMBINATION OF DEEP LYR
SHEAR/EFFECTIVE SRH/MLCAPE/ML LCL SUGGEST AN ISOLATED TORNADO OR 2
WILL BE POSSIBLE.  TUES AFTN/EVENING THEN...SVR POTENTIAL REMAINS
FOCUSED OVER THE SRN CWA ALONG A SFC BNDRY ALONG THE NEB/KS BORDER.
ENVIRONMENTAL CONDITIONS WILL QUITE SIMILAR WITH THE POTENTIAL FOR
PRODUCING AN ISOLATED TORNADO OR 2.

IN REGARDS TO POPS THE REST OF THIS WEEK...AM COMPELLED TO MAINTAIN
PCPN CHANCES THRU THE MAJORITY OF THE FCST PERIOD GIVEN MODELS
ADVERTISING PERSISTENT FORCING VIA UPPER LEVEL DIVERGENCE...SERIES
OF VORT IMPULSES...ISENTROPIC UPGLIDE...MEANDERING SFC
BOUNDARIES...AS WELL AS GENEROUS MOISTURE TO TAP INTO.

DEE

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1107 PM CDT SUN MAY 26 2013

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-271815-
MONONA-HARRISON-SHELBY-POTTAWATTAMIE-MILLS-MONTGOMERY-FREMONT-
PAGE-KNOX-CEDAR-THURSTON-ANTELOPE-PIERCE-WAYNE-BOONE-MADISON-
STANTON-CUMING-BURT-PLATTE-COLFAX-DODGE-WASHINGTON-BUTLER-
SAUNDERS-DOUGLAS-SARPY-SEWARD-LANCASTER-CASS-OTOE-SALINE-
JEFFERSON-GAGE-JOHNSON-NEMAHA-PAWNEE-RICHARDSON-
1107 PM CDT SUN MAY 26 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MOST OF EASTERN NEBRASKA AND
PARTS OF SOUTHWEST IOWA.

.DAY ONE...TONIGHT AND MONDAY

A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR MOST OF THE AREA
UNTIL 5 AM CDT. SOME ISOLATED SEVERE STORMS WITH LARGE HAIL AND
DAMAGING WINDS WILL BE POSSIBLE...ESPECIALLY ACROSS NORTHEAST
NEBRASKA. HEAVY RAINFALL IS LIKELY WITH ANY STORMS THAT DEVELOP
TONIGHT...AND COULD CAUSE LOCALIZED FLOODING.

UNSTABLE CONDITIONS WILL REMAIN ACROSS THE AREA ON MONDAY WITH A
CONTINUED CHANCE OF THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...MONDAY NIGHT THROUGH SATURDAY

INTERMITTENT PERIODS OF THUNDERSTORMS ARE POSSIBLE MONDAY NIGHT
THROUGH WEDNESDAY...WITH SOME POTENTIAL FOR SEVERE STORMS. THESE
THUNDERSTORMS WILL FAVOR THE EVENING AND OVERNIGHT HOURS WITH
LOCALLY HEAVY RAIN LIKELY.

BETTER CHANCES FOR SEVERE THUNDERSTORMS WILL COME THURSDAY AND
FRIDAY AS STRONGER WINDS AND COOLER TEMPERATURES AT MID LEVELS
OVERSPREAD THE REGION. EXACT TIMING OF THE GREATEST POTENTIAL FOR
SEVERE WEATHER WILL BE OUTLINED WITH LATER OUTLOOKS.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTER ACTIVATION WILL PROBABLY NOT BE NEEDED OVERNIGHT...
BUT PLEASE PASS ALONG ANY SEVERE WEATHER REPORTS. STORM SPOTTER
ACTIVATION MAY BE REQUIRED LATE MONDAY AFTERNOON OR EVENING.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
820 PM CDT SUN MAY 26 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0730 PM     HAIL             7 NNE STANTON           41.07N 95.05W
05/26/2013  E1.25 INCH       MONTGOMERY         IA   PUBLIC

&&

JRB

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