Severe Thunderstorm Warning 330, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
221 AM CDT SAT JUL 5 2008

.DISCUSSION...
THUNDERSTORM CHANCES THROUGH TUESDAY REMAIN THE PRIMARY FORECAST
CONCERNS.

ISOLATED STORMS DEVELOPED THIS MORNING...SHORTLY AFTER MIDNIGHT...IN
PLUME OF INCREASINGLY HIGHER THETA-E AIR IN CENTRAL NEBRASKA. SOME
OF THOSE STORMS WILL LIKELY AFFECT WESTERN PARTS OF THE CWA THIS
MORNING. STORMS WILL END BY NOON AS WARM ADVECTION REGIME SHIFTS
NORTHEAST AHEAD OF STRONG SHORTWAVE ROLLING EAST ALONG THE CANADIAN
BORDER. RESULTANT LOWERING SURFACE PRESSURE IN THE DAKOTAS WILL
TIGHTEN PRESSURE GRADIENT ACROSS OUR AREA...CAUSING BRISK SOUTHERLY
WINDS AND INCREASINGLY WARMER 850 AIR. COMBINATION OF SUNSHINE...
MIXING AND WARMER LOW LEVEL AIR SHOULD PUSH TEMPS TOWARD 90 IN MUCH
OF THE CWA THIS AFTERNOON.

THUNDERSTORMS ARE EXPECTED TO FIRE IN THE CENTRAL DAKOTAS LATER IN
THE DAY AS MOISTURE ADVECTION SURGES NORTH AHEAD OF SURFACE LOW
PRESSURE. THOSE STORMS SHOULD PROPAGATE SOUTHEAST OVERNIGHT AS
SOUTHWEST 850 FLOW FEEDS EASTWARD MOVING LINES...WITH SOME STORMS
POSSIBLE INTO NORTHEAST NEBRASKA AFTER MIDNIGHT.

ANY STORMS THAT DO MAKE IT INTO OUR CWA SHOULD DISSIPATE SUNDAY
MORNING...BUT RESULT WILL BE STRENGTHENING BAROCLINIC ZONE ACROSS
EASTERN NEBRASKA. BOTH NAM AND GFS SHOW THIS...AND BOTH PUSH SURFACE
DEW POINTS TO OR ABOVE 70F SUNDAY AFTERNOON. ALTHOUGH LOW LEVEL
CONVERGENCE WILL BE WEAK WITH MINIMAL 0-6KM BULK SHEAR...
SURFACE-BASED CAPES WILL EXCEED 3000 J/KG. EXPECT SOME PULSE STORMS
TO GET GOING IN THIS JUICY ENVIRONMENT...ESPECIALLY IN AREAS NEAR
SURFACE CONVERGENCE WHERE TEMPERATURES JUST SOUTH SHOULD EASILY TOP
90 AND BREAK WEAK CAP.

PERHAPS BEST CHANCE FOR ORGANIZED STORMS WILL COME MONDAY WHEN GFS
AND NAM SHOW MORE SIGNIFICANT MID LEVEL COOLING WITH A SHORTWAVE
DROPPING INTO THE PLAINS. SURFACE DEW POINTS WILL STILL BE NEAR 70
WITH BULK SHEAR INCREASING WITH APPROACHING WAVE. AGAIN SBCAPES
WILL TOP 3000 J/KG WITH NO CAP. LOW LEVEL CONVERGENCE SHOULD BE
ENHANCED AS INDUCED SURFACE LOW TRAVELS NORTHEAST ALONG FRONTAL
BOUNDARY...SO SHOULD NOT HAVE A PROBLEM GETTING THINGS GOING IN
THE HEAT OF THE AFTERNOON. STORMS WILL SHIFT SOUTHEAST WITH TIME
OVERNIGHT ON BACK SIDE OF EXITING UPPER TROUGH/SURFACE LOW WITH A
LINGERING STORM POSSIBLE TUESDAY MORNING IN SOUTHEAST NEBRASKA.

THE REST OF THE FORECAST WAS LEFT BASICALLY UNCHANGED FOR NOW. GFS
SHOWS A RELATIVELY COOL PERIOD TUESDAY AND WEDNESDAY WITH HIGHS
SLIGHTLY BELOW NORMAL. WE COULD SEE ANOTHER ROUND OF STORMS
WEDNESDAY NIGHT OR THURSDAY AS WARM ADVECTION REGIME IN RETURN FLOW
OVERSPREADS THE REGION...BUT WILL NOT INTRODUCE JUST YET.

&&

.AVIATION...
FOR TAF SITES KOMA/KLNK/KOFK THROUGH 06/12Z.

THETA-E ADVECTION UNDERWAY WITH ACCAS FM AROUND BLUE HILL (KUEX) TO
WEST OF NELIGH.  PROFILERS/VWPS HAVE 30 TO 40KTS AT H85 AND
BEGINNING TO SEE SOME RETURNS JUST WEST OF THE CWA.  THETA-E
ADVECTION WILL CONTINUE OVERNIGHT AND THIS  MORNING SHIFTING
EASTWARD WITH TIME ACRS ERN NEB AND WRN IA ALONG WITH THE MOISTURE
AXIS.  EXPECT VFR CIGS AND POSSIBLY SOME LOCAL IFR/MVFR CIGS WITH
THE SHRA/TSRA. SINCE THERE IS A LARGE FOCUS AREA HAVE CB IN THE
OFK/LNK TAFS THRU 14Z AND MAY NEED TO ADD TO THE OMA TAF.  FREEZING
LEVELS ARE HIGH AND STORM MOTIONS ARE WEAK...LESS THAN 10 KTS...SO
SHOULD ONE OF THE STORMS GO OVER A SITE...VISIBILTIES COULD DROP TO
THE IFR/LIFR RANGE.  SFC WINDS INCREASE TO 15 TO 30KTS AFTER 14Z AND
THIS SHOULD HELP MIX THE CLOUDS OUT TO SCT FOR LATER IN THE
AFTERNOON.

&&

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

DISCUSSION...DERGAN
AVIATION...ZAPOTOCNY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
528 AM CDT SAT JUL 5 2008

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-060030-
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-
528 AM CDT SAT JUL 5 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
IOWA...WEST CENTRAL IOWA...EAST CENTRAL NEBRASKA...NORTHEAST
NEBRASKA AND SOUTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS IN EASTERN NEBRASKA MAY PRODUCE AN
ISOLATED LARGE HAIL EVENT THROUGH MID MORNING. THE STORMS SHOULD
DISSIPATE BY NOON.

ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE IN NORTHEAST NEBRASKA
AFTER MIDNIGHT. THERE IS A SLIGHT CHANCE FOR LARGE HAIL OR
DAMAGING WINDS WITH THESE STORMS...MAINLY NORTH OF A COLUMBUS TO
ONAWA LINE.

THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE AFTERNOON AHEAD OF A
COLD FRONT IN THE DAKOTAS. THE EXPECTED SOUTHEAST MOVEMENT WOULD
BRING THE STORMS INTO NORTHEAST NEBRASKA AFTER MIDNIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

MORNING THUNDERSTORMS ARE POSSIBLE SUNDAY IN NORTHEAST NEBRASKA
AND WEST CENTRAL IOWA...BUT SHOULD BE WEAKENING. ANOTHER ROUND OF
STORMS IS POSSIBLE SUNDAY AFTERNOON AS HIGH HUMIDITY LENDS TO HIGH
INSTABILITY DURING THE HEAT OF THE AFTERNOON. IF STORMS DO
DEVELOP...LARGE HAIL AND DAMAGING WINDS COULD OCCUR.

A BETTER CHANCE FOR SEVERE THUNDERSTORMS WILL COME MONDAY AS A LOW
PRESSURE SYSTEM ROLLS THROUGH THE AREA. LARGE HAIL AND DAMAGING
WINDS WILL BE POSSIBLE MONDAY AFTERNOON AND EVENING ACROSS ALL OF
EASTERN NEBRASKA AND SOUTHWEST IOWA. THESE STORMS WILL LIKELY
CONTINUE THROUGH THE NIGHT...BUT SHOULD BE EXITING SOUTHEAST
NEBRASKA TUESDAY MORNING.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTER ACTIVATION SHOULD NOT BE NEEDED TODAY OR TONIGHT.

DERGAN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
512 AM CDT SAT JUL 05 2008

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

0456 AM     HAIL             COLUMBUS                41.43N 97.36W
07/05/2008  E0.88 INCH       PLATTE             NE   EMERGENCY MNGR

0507 AM     HAIL             3 SW MILFORD            40.74N 97.09W
07/05/2008  E1.75 INCH       SEWARD             NE   LAW ENFORCEMENT

&&

CZAPOTOC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
736 AM CDT SAT JUL 05 2008

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

0731 AM     HAIL             8 S FRIEND              40.54N 97.28W
07/05/2008  M0.88 INCH       SALINE             NE   TRAINED SPOTTER

&&

DERGAN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
738 AM CDT SAT JUL 05 2008

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

0712 AM     HAIL             4 S HOWELLS             41.67N 97.00W
07/05/2008  M1.00 INCH       COLFAX             NE   TRAINED SPOTTER

&&

DERGAN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
801 AM CDT SAT JUL 05 2008

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

0745 AM     HAIL             4 S HOWELLS             41.67N 97.00W
07/05/2008  M1.50 INCH       COLFAX             NE   TRAINED SPOTTER

            ALSO REPORTED 4 INCHES OF RAIN

&&

DERGAN