Severe Thunderstorm Warning 196, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
201 PM CDT SAT AUG 22 2015

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 200 PM CDT SAT AUG 22 2015

THE PRIMARY FORECAST CONCERNS ARE TSTM/SEVERE WEATHER POTENTIAL
AND TIMING OF PCPN THROUGH TONIGHT.

AN USUALLY STRONG WEATHER SYSTEM WILL AFFECT AT LEAST PARTS OF THE
REGION INTO TONIGHT. UPPER AIR CHARTS FROM 12Z SHOWED A 95 KNOT
JET MAX AT 300 MB DIGGING SOUTHEAST FROM WESTERN MONTANA INTO
WYOMING. 12 HOUR HEIGHT FALLS AT 500 MB WERE AROUND 70 METERS IN
EASTERN MONTANA. WATER VAPOR LOOP IN COMBINATION WITH MOST RECENT
RUC MODEL INITIALIZATIONS SHOWED A CLOSED LOW AT 500 MB OVER
WESTERN NORTH DAKOTA WITH STRONGEST HEIGHT FALLS MOVING ACROSS
THE DAKOTAS. 700 MB TEMPERATURES TO OUR WEST AT 12Z WERE QUITE
WARM...14 TO 15 DEGREES C...FROM SOUTHWEST SOUTH DAKOTA DOWN INTO
WEST TEXAS. THESE WILL DECREASE LATER. 850 MB MOISTURE WAS NOT
OVERLY HIGH...BUT ADEQUATE...WITH DEWPOINTS OF 16 DEGREES C AT
KLBF AND KOAX.

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWED A COUPLE OF TROUGHS
AHEAD OF THE MAIN FRONT. ONE OF THESE TROUGHS EXTENDED FROM
NORTHWEST IOWA DOWN INTO EASTERN NEBRASKA. WINDS HAD VEERED TO
THE SOUTH/SOUTHWEST WITH THE PASSAGE OF THIS FEATURE. MOISTURE
WAS INCREASING AHEAD OF IT...WITH DEWPOINTS IN THE UPPER 60S AND
LOWER 70S. THIS WILL BE A FEATURE TO MONITOR.

STORMS WILL AFFECT PARTS OF THE AREA THROUGH THE EVENING AND INTO
TONIGHT. HIGHEST COVERAGE EXPECTED IN THE AREA FROM NORTH AND
EAST OF OMAHA ACROSS WESTERN IOWA AND ALSO DOWN INTO PARTS OF
SOUTHEAST NEBRASKA AND NORTHWEST MISSOURI. MODELS GENERALLY SHOW
0-6 KM BULK SHEAR OF 25-50 KNOTS WITH THE STORMS...AND ML CAPE
VALUES 1000-2500 J/KG. SEVERE RISK IS MAINLY BEFORE 10 OR 11 PM...
AND DROPS OFF AFTER THAT. PARAMETERS SHOULD BE IN PLACE FOR STORMS
TO INITIALLY BE SUPERCELLS...WITH THESE THEN FORMING/MERGING INTO
A LINE. TORNADOES POSSIBLE FOR A FEW HOURS...MAINLY NEAR ANY LOW
LEVEL BOUNDARIES.

LATER TONIGHT...ELEVATED INSTABILITY LINGERS FOR A WHILE BEFORE
GETTING PUSHED OFF TO THE EAST AND SOUTH. WE THEN EXPECT MAINLY
DRY WEATHER FROM SUNDAY INTO TUESDAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 200 PM CDT SAT AUG 22 2015

GENERALLY USED A MODEL BLEND FOR THIS PERIOD. 500 MB RIDGE INITIALLY
OVER THE ROCKIES EARLY ON WILL TRY TO RETROGRADE BACK TO THE
SOUTHWEST LATER IN THE WEEK. SHORTWAVE ENERGY MOVING DOWN IN THE
NORTHWEST FLOW WILL BE DIFFICULT TO TIME...BUT EXPECT SOME CHANCE OF
SHOWERS AND STORMS OFF AND ON INTO NEXT WEEKEND.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1229 PM CDT SAT AUG 22 2015

CONVECTIVE POTENTIAL WILL EXTEND THROUGH ABOUT 02Z AS A COLD FRONT
MOVES THROUGH THE AREA WITH THREAT DECREASING FROM WEST TO EAST
DURING THAT TIME. MVFR CIGS AND VSBY WITH THE CONVECTION THEN BECOMING
VFR AFTER 02Z AND CONTINUING THROUGH THE REMAINDER OF THE PERIOD.

&&

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

SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...FOBERT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
505 PM CDT SAT AUG 22 2015

IAZ043-055-056-069-079-080-090-091-NEZ015-033-034-043>045-050>053-
065>068-078-088>093-231215-
MONONA-HARRISON-SHELBY-POTTAWATTAMIE-MILLS-MONTGOMERY-FREMONT-
PAGE-THURSTON-CUMING-BURT-COLFAX-DODGE-WASHINGTON-BUTLER-SAUNDERS-
DOUGLAS-SARPY-SEWARD-LANCASTER-CASS-OTOE-SALINE-JEFFERSON-GAGE-
JOHNSON-NEMAHA-PAWNEE-RICHARDSON-
505 PM CDT SAT AUG 22 2015

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

.DAY ONE...TONIGHT AND SUNDAY

A TORNADO WATCH HAS BEEN ISSUED IN EFFECT UNTIL MIDNIGHT LOCAL
TIME. THUNDERSTORMS ARE EXPECTED TO DEVELOP AND THEN SPREAD
SOUTHEAST ACROSS THE AREA.

STORMS INTO MID EVENING WILL HAVE A RISK OF LARGE HAIL...DAMAGING
WINDS AND POSSIBLY A TORNADO OR TWO. LATER IN THE EVENING...AS
STORMS FORM MORE OF A LINE...DAMAGING WINDS AND LARGE HAIL WILL
BECOME THE PRIMARY RISKS. BRIEF HEAVY RAINFALL ALSO WILL BE
POSSIBLE WITH THESE THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SMALL CHANCES FOR THUNDERSTORMS RETURN TO THE AREA ON WEDNESDAY
NIGHT THROUGH SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS MAY BE NEEDED THROUGH THE EVENING...ESPECIALLY SOUTHEAST
OF A LINE FROM DAVID CITY TO ONAWA.

NEZ011-012-016>018-030>032-042-231215-
KNOX-CEDAR-ANTELOPE-PIERCE-WAYNE-BOONE-MADISON-STANTON-PLATTE-
505 PM CDT SAT AUG 22 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
NEBRASKA.

.DAY ONE...TONIGHT AND SUNDAY

THUNDERSTORMS ARE POSSIBLE EARLY THIS EVENING AS A COLD FRONT
MOVES ACROSS THE AREA.

.DAYS TWO THROUGH SEVEN...SUNDAY NIGHT THROUGH SATURDAY

SMALL CHANCES FOR THUNDERSTORMS RETURN TO THE AREA ON WEDNESDAY
NIGHT THROUGH SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED TONIGHT OR SUNDAY.

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
550 PM CDT SAT AUG 22 2015

IAZ055-056-069-NEZ052-222315-
SHELBY IA-HARRISON IA-POTTAWATTAMIE IA-DOUGLAS NE-
550 PM CDT SAT AUG 22 2015

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL POTTAWATTAMIE...
SOUTHEASTERN HARRISON...SOUTHWESTERN SHELBY AND EAST CENTRAL DOUGLAS
COUNTIES UNTIL 615 PM CDT...

AT 549 PM CDT...DOPPLER RADAR WAS TRACKING A LINE OF STRONG
THUNDERSTORMS FROM NEAR PERSIA SOUTHWEST TO NEAR CARTER LAKE
AND...MOVING EAST AT 30 MPH.

DIME SIZE HAIL AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH
THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
EASTERN OMAHA...NORTHEASTERN COUNCIL BLUFFS...OAKLAND...AVOCA...
UNDERWOOD...CARSON...SHELBY...MINDEN...PERSIA...CARTER LAKE...
NEOLA...CRESCENT...HANCOCK...PORTSMOUTH...MCCLELLAND...TENNANT...
ARROWHEAD PARK...NARROWS RIVER PARK...NISHNA BEND RECREATION AREA AND
BOTNA BEND PARK.

THIS INCLUDES THE FOLLOWING HIGHWAYS...
 HIGHWAY 59 IN IOWA BETWEEN MILE MARKERS 48 AND 73.
 INTERSTATE 29 BETWEEN MILE MARKERS 55 AND 63.
 INTERSTATE 80 IN IOWA BETWEEN MILE MARKERS 8 AND 43.

THESE STORMS MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

A TORNADO WATCH REMAINS IN EFFECT UNTIL MIDNIGHT CDT FOR SOUTHWESTERN
IOWA AND EAST CENTRAL NEBRASKA.

LAT...LON 4158 9523 4123 9541 4127 9589 4134 9594
      4155 9576 4167 9558
TIME...MOT...LOC 2249Z 262DEG 27KT 4154 9562 4131 9590

BOUSTEAD