Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 161751
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1251 PM CDT THU APR 16 2015

.UPDATE...
ISSUED AT 630 AM CDT THU APR 16 2015

SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO MOVE EAST/NORTHEAST
FROM CENTRAL NEBRASKA AS OF AROUND 635 AM. MOST OF THE RECENT
SHORT RANGE HIGH RESOLUTION MODELS KEEP SOME SPOTTY ACTIVITY GOING
INTO EARLY AFTERNOON...MAINLY IN EASTERN NEBRASKA BUT ALSO IN
PARTS OF SOUTHWEST IOWA NORTH OF OMAHA. CLOUDS WERE VARIABLE AS OF
635 AM WITH SOME AREAS OF FOG WHERE SKIES HAD CLEARED EARLIER.

BEST FOCUS FOR STORMS SEEMS TO SHIFT BACK TOWARD THE HIGH PLAINS
BY MID TO LATE AFTERNOON.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 315 AM CDT THU APR 16 2015

PCPN CHANCES AND TEMPERATURES ARE THE PRIMARY FORECAST CONCERNS
IN THE TODAY PERIOD...THEN INCREASING COVERAGE OF SHOWERS AND
THUNDERSTORMS TONIGHT THROUGH SATURDAY AND TEMPERATURES.

CLUSTER OF STORMS THAT FORMED OVER NORTHWEST KANSAS LAST EVENING
CONTINUED TO LIFT NORTHEAST EARLY THIS MORNING. SOME OF THE SHORT
RANGE MODELS BRING THAT PCPN INTO OUR AREA THIS MORNING BEFORE IT
DISSIPATES. THE ATMOSPHERE HAS BEEN RELATIVELY STABLE SO FAR
EARLY THIS MORNING WITH INSTABILITY AXIS FARTHER WEST. FORECAST
SOUNDINGS BRING SOME INSTABILITY INTO OUR AREA BY MID MORNING AND
THEN THIS SHOULD INCREASE SLIGHTLY THE REST OF THE DAY. SCATTERED
STORMS WILL BE POSSIBLE THIS MORNING...MAINLY IN EASTERN
NEBRASKA...THEN FOR ALL OF THE FORECAST AREA THIS AFTERNOON. BEST
CHANCES ARE EXPECTED TO REMAIN GENERALLY WEST OF LINE FROM AROUND
WAYNE TO FALLS CITY.

CLOUD COVER IS EXPECTED TO REMAIN IN PLACE MUCH OF THE MORNING BUT
MAY BREAK UP A BIT IN THE AFTERNOON...ALLOWING FOR SOME HEATING.
STAYED TOWARD THE LOWER END OF MODEL GUIDANCE FOR TODAY...WITH HIGHS
MOSTLY IN THE UPPER 60S AND LOWER 70S.

TONIGHT...THE MID TROPOSPHERIC LOW OVER THE FOUR-CORNERS REGION WILL
DRIFT NORTHEAST TO COLORADO. THE H5 LOW MEANDERS OVER COLORADO
FRIDAY AND FRIDAY NIGHT...MOVING INTO THE WESTERN KANSAS SATURDAY.
THE 0.83 PWAT ON THE 00Z SOUNDING WAS 170% OF NORMAL.  CONTINUED
SOUTHEAST LOW LEVEL FLOW WILL HOLD PWAT VALUES FROM 1.00-1.25
THROUGH 18Z SATURDAY...THEN 0.75 THROUGH SUNDAY MORNING WITH
DRYING FROM THE WEST. THE FORCING FOR PRECIPITATION WITH THE
SURFACE LOW OVER EASTERN COLORADO WILL TEND TO BE OVER WESTERN AND
CENTRAL PARTS OF KANSAS AND NEBRASKA INTO COLORADO AND WYOMING.
THIS FORCING TENDS TO WEAKEN AT IS MOVES TOWARD THE MISSOURI RIVER
AND WESTERN IOWA. THE NAM/GFS/EC MODELS DID NOT DO WELL ON THE
POSITION OF THE CLUSTER OF STORMS TO THE WEST AT 06Z HOWEVER THE
HIRES RAP/HRRR AND 4KM WRF NMM MODELS DID BETTER...SO HARD TO BE
CONFIDENT WITH PRECIP PLACEMENT. FOR NOW...HAVE THE HIGHEST POPS
FOR THUNDERSTORMS WITH LIKELY POPS...OVER WESTERN PARTS OF THE
FORECAST AREA OF RESPONSIBILITY AND WILL HAVE A GRADIENT IN POPS
FROM WEST TO EAST...WITH ISOLATED/CHC POPS IN WESTERN IOWA.

FRIDAY THROUGH SATURDAY SCATTERED THUNDERSTORMS WILL BE MORE COMMON
ACROSS THE FORECAST AREA.  TYPICAL RAINFALL AMOUNTS WILL VARY FROM A
TRACE TO .5" IN EACH 6 HOUR PERIOD.  FOR THAT 48HRS A REASONABLE
RANGE FOR RAIN TOTALS WOULD BE HALF AN INCH TO 2 INCHES OF
RAINFALL...WITH THE TYPICAL LOWER AND HIGHER OUTLIERS POSSIBLE.

HIGHS FRIDAY AND SATURDAY SHOULD STILL BE MILD IN THE 60S AND 70S
WITH EAST OR SOUTHEASTERLY SURFACE WINDS 5 TO 20 MPH EACH DAY.
IF HEATING IS REALIZED...INSTABILITY INCREASES FRIDAY TO
1000-1500J/KG...SO CANNOT RULE OUT SOME HAIL WITH THE STRONGEST
STORMS. THE SPC HAS THE MARGINAL RISK IN SOUTHERN NEBRASKA.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 315 AM CDT THU APR 16 2015

THE CLOSED LOW OVER WESTERN KANSAS OPENS UP INTO AN OPEN WAVE
THAT EXTENDS FROM H5 LOW PRESSURE OVER CANADA THROUGH SUNDAY.
SURFACE LOW PRESSURE OVER THE WESTERN PLAINS SHIFTS INTO MISSOURI
AND IOWA. THE SURFACE FRONT PUSHES EAST...WITH THE COLD FRONT
MOVING THROUGH MUCH OF THE FORECAST AREA BY 18Z SUNDAY. H85 WINDS
FROM THE NORTHWEST INCREASE TO 40KTS...SO IT WILL BE WINDY BEHIND
THE FRONT. THE GFS KEEPS TEMPERATURES WARM ENOUGH FOR THE
PRECIPITATION TO REMAIN LIQUID THROUGH SUNDAY. THE ECMWF IS A
LITTLE COLDER AND SLOWER TO END THE PRECIPITATION...SO THESE
DETAILS CAN BE FIRMED UP AS WE GET CLOSER TO THE ENDING OF THE
EVENT. BRISK NORTHWEST WINDS CONTINUE MONDAY. COOLER HIGHS FOR THE
EXTENDED IN THE 50S AND 60S. MAY BE A SMALL CHANCE FOR SHOWERS
TUESDAY NIGHT THRU WEDNESDAY AS THE BROAD H5 TROF CENTERED OVER
THE GREAT LAKES INTO CANADA PERSISTS.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1239 PM CDT THU APR 16 2015

RADAR MOSAIC THIS AFTN SHOWING SCT SHRA LIFTING NEWD ACROSS ERN
NEB WITH GENERALLY MVFR CONDITIONS ACCOMPANYING THE PCPN ACTIVITY.
TRENDS THE LAST SEVERAL HOURS HINT THE TAF SITES WILL SEE BRIEF PD
OF -SHRA/MVFR CONDITIONS THE NEXT COUPLE HOURS...THUS HAVE INCLUDED
TEMPO GROUPS TO COVER THIS. OTHERWISE...EXPECT VFR CONDITIONS TO
PREVAIL UNTIL EARLY FRI MORNING WHEN SCT TSRA ACTIVITY BEGINS
EXPANDING FROM WEST TO EAST AND INCREASES IN AREAL COVERAGE OVER
ERN NEB. THUS HAVE INTRODUCED TEMPO GROUPS AT ALL TERMINALS IN
ANTICIPATION OF THIS.

&&

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

$$

UPDATE...MILLER
SHORT TERM...MILLER/ZAPOTOCNY
LONG TERM...ZAPOTOCNY
AVIATION...DEE


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