Flash Flood and Flood in Nebraska, August 27 to 28, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
648 PM CDT THU AUG 27 2015

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 255 PM CDT THU AUG 27 2015

TSTM CHANCES WITH ASSOCIATED POTENTIAL FOR SEVERE STORMS AND
HEAVY RAIN WILL PROVIDE THE MAIN FORECAST CHALLENGES INTO FRIDAY
MORNING.

MID LEVEL SHORTWAVE TROUGH TO OUR WEST...WHICH HAD 12 HOUR HEIGHT
FALLS OF UP TO AROUND 60 METERS AT 500 MB AT 122...WILL CONTINUE
TO MOVE EWD TONIGHT. 12Z KOAX SOUNDING WAS FAIRLY MOIST WITH A PW
OF 1.69 INCHES AND MU CAPE OF AROUND 3200 J/KG. MOST RECENT WATER
VAPOR IMAGERY SHOWED ENERGY STILL MOVING TOWARD THE LOCAL
AREA...SO STORM COVERAGE SHOULD INCREASE LATE AFTN/EARLY EVENING.

SURFACE ANALYSIS AT 19Z SHOWED LOW PRESSURE CENTERED NEAR KMCK.
A WARM FRONT CURVED S/SE FROM THE LOW DOWN INTO CNTRL KS...WHILE A
COLD FRONT WAS BECOMING BETTER DEFINED FROM WRN NE INTO WRN KS.
MU CAPE VALUES WERE AROUND 3000 J/KG FROM PARTS OF CNTRL NE INTO
NCNTRL KS. 0-6 KM SHEAR WAS ADEQUATE...MAINLY 30-40 KNOTS.

PW VALUES SHOULD INCREASE TO NEAR 2.00 INCHES TONIGHT FOR MUCH OF
THE AREA. THE BEST PARAMETERS FOR HEAVY RAIN SEEM TO BE COMING
TOGETHER ACROSS NERN NE/SERN SD/WRN IA/SWRN MN. WILL MENTION AREAS
OF HEAVY RAIN TONIGHT ACROSS OUR NRN ZONES.

PCPN CHANCES WILL DECREASE FROM W TO E LATER TONIGHT AND FRIDAY
AS LOW PRESSURE CENTER AND COLD FRONT WILL MOVE EAST OF THE AREA.
KEPT SOME LINGERING CHANCES FOR PCPN MUCH OF THE DAY...BUT BEST
CHANCES ARE EXPECTED PRIOR TO 18Z. WEAK HIGH PRESSURE BUILDS IN
FOR FRIDAY NIGHT...AND WITH LIGHT WINDS WE EXPECTED AT LEAST SOME
PATCHY FOG. DRY OR MAINLY DRY CONDITIONS ARE FORECAST FOR THE
WEEKEND WITH HIGHS IN THE 80S.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 255 PM CDT THU AUG 27 2015

PATTERN AT THE START OF THIS SHOULD HAVE A 500 MB RIDGE EXTENDING
FROM NM TO WI AND A FAIRLY DEEP TROUGH FROM WRN CANADA DOWN INTO
CNTRL CA. THESE FEATURES WILL NOT CHANGE MUCH THROUGH MID WEEK. THE
BEST FORCING AND MOISTURE FOR PCPN SHOULD STAY TO OUR N AND W.

TEMPERATURES THROUGH THE PERIOD SHOULD AVERAGE AT OR ABOVE NORMAL.

&&

.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 636 PM CDT THU AUG 27 2015

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT FOR PARTS OF EASTERN
AND CENTRAL NEBRASKA UNTIL MIDNIGHT. KOFK MAY BE TAF SITE MOST AT
RISK OF SEEING STRONG THUNDERSTORM ACTIVITY THROUGH ABOUT 05Z.
COLD FRONT NOW IN WESTERN NEBRASKA WILL MOVE ACROSS CENTRAL AND
EASTERN NEBRASKA...INTO WESTERN IOWA OVERNIGHT AND WIDESPREAD
CONVECTION WILL OCCUR ALONG THE FRONTAL BOUNDARY AS IT SWEEPS
ACROSS THE REGION. THE FRONT WILL BE EAST OF ALL THREE TAF SITES
AFTER 15Z WITH WINDS BECOMING NORTHWEST AFTER FRONTAL PASSAGE. SOME
MVFR CIGS EXPECTED TO LINGER ON THE BACK SIDE OF THE FRONT THROUGH
18Z.

&&

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

SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...MEYER

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
957 PM CDT THU AUG 27 2015

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-281700-
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-
957 PM CDT THU AUG 27 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 FRIDAY

THUNDERSTORM ACTIVITY WILL GRADUALLY DISSIPATE BY EARLY FRIDAY
MORNING.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH THURSDAY

HAZARDOUS WEATHER IS NOT ANTICIPATED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.