Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 310447
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1147 PM CDT SAT AUG 30 2014

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 300 PM CDT SAT AUG 30 2014

PRIMARY FOCUS FOR SHORT TERM REMAINS CONVECTIVE DEVELOPMENT ON
SUNDAY AS MODELS CONTINUE TO INDICATE THE SEVERE WEATHER AND
LOCALLY HEAVY RAIN THREAT PERSISTS.

BROAD UPPER TROUGH WAS CROSSING THE ROCKIES TODAY PER LATEST WATER
VAPOR IMAGERY WITH 12Z UA INDICATING LARGE AREA OF 50M HGT FALLS
AT H5 FM OR/WA INTO MT. IN RESPONSE TO THE TROUGH/S APPROACH
...LOW LEVEL JET SHOULD INCREASE TONIGHT AND RESULTANT ISENTROPIC
UPGLIDE COULD KICK OFF MAINLY ISOLD/HIGH BASED TSTMS LATE. MODEL
TREND...SPCLY ECMWF...HAS BEEN TO EITHER DELAY SLIGHTLY OR MOSTLY
IGNORE. BUT SOME SMALL POPS STILL SEEMED WARRANTED...BUT THEY
WERE DELAYED JUST A BIT AND TRIMMED BACK A LITTLE SUNDAY MORNING.
LITTLE CHANGES TO LOW TEMPERATURES TNGT.

FALLING HEIGHTS AND SOME INCREASE IN MOISTURE SHOULD ERODE CAP
SUNDAY AFTN...THINKING 21Z ISH...ALTHOUGH SLIGHT DIFFERENCES
EXISTED ON WHERE MAIN INITIATION WOULD TAKE PLACE. EITHER NERN
NEBR/NW IA PER NAM OR ECNTRL NEB/SW IA PER ECMWF. GFS WAS MORE OF
A COMPROMISE. HOWEVER...JET AND FALLING HGTS COULD INCREASE
COVERAGE BEHIND MAIN INITIATION AREA BY 00Z. ALTHOUGH MOST AREAS
WILL HAVE HIGH LIKELY OR CATEGORICAL POPS BY EVENING...WHERE
INITIAL DEVELOPMENT OCCURS COULD ACT AS FOCUS ON WHERE HEAVIEST
PRECIP EVENTUALLY OCCURS. FOR THIS REASON NO FLASH FLOOD WATCH
WILL BE ISSUED JUST YET...BUT HEAVY RAIN MENTION WILL BE CARRIED
MUCH OF THE CENTRAL/ERN ZONES IN THE EVENING/EARLY OVERNIGHT HRS
AS PRECIPITABLE WATER VALUES INCREASE TO OVER 2 INCHES ALONG FRONT
PER NAM...WITH A LITTLE LESS THAN THAT FROM GFS. WITH 0-6KM SHEAR
VALUES INCREASING TO 40 KTS+ MOST AREAS...SEVERE THREAT ALSO
PERSISTS WITH HP SUPERCELLS A DECENT BET PER SWODY2.

WITH LOW LEVEL JET REMAINING SWRLY SERN ZONES THROUGH 12Z MONDAY
SOME PRECIP COULD LINGER INTO MONDAY MORNING...BUT WOULD SUSPECT
EVENTUAL COLD POOL COULD FORCE BULK OF MCS E OF FA BY DAYBREAK.

WITH TROUGHY NATURE TO UPPER FLOW ON LABOR DAY/MONDAY
NIGHT...NEXT WAVE QUICKLY APPROACHES AND COULD ALREADY GENERATE
AFTN SHOWERS/TSTMS INTO WRN ZONES AT LEAST. IF TRENDS WOULD
PERSIST COULD FORESEE NEED TO INCLUDE PCPN IN LATER FORECASTS
LABOR DAY AFTN BUT FOR NOW LEFT IT DRY. WITH LOSS OF HEATING AND
A LOT OF THE MOISTURE CLEARED OUT BY SUN EVENING/S MCS...ACTIVITY
COMING ACROSS THE FA WITH THE WAVE MON NGT SHOULD BE WEAKENING
WITH COVERAGE NOT ESPECIALLY HIGH.  THUS ONLY SLGT CHC/LOW END
CHANCE POPS WERE MAINTAINED. TUE APPEARS DRY FOR NOW. COOLER MAX
TEMPS FOR LABOR DAY/TUESDAY LOOKED GOOD WITH NO SIG CHANGES OR
VARIANCE FROM GUIDANCE.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 300 PM CDT SAT AUG 30 2014

WEDNESDAY/THURSDAY PERIODS WERE KEPT DRY...SUPPORTED BY 12Z GFS
AND FOR CONTINUITY PURPOSES. A WARMING TREND SHOULD COMMENCE. IT
WAS NOTED HOWEVER THAT ECMWF WAS QUICKER IN DRIVING A FRONT INTO
FA THURSDAY AS WAVE TRACKS ACROSS SRN CANADA...ALTHOUGH NO PRECIP
WAS GENERATED UNTIL THURSDAY NIGHT. WHICH A CASE COULD BE MADE
WITH EARLIER DAY TIMING OF FRONT AND HIGH UPPER HGTS INITIALLY.
TSTM CHANCES THEN WERE MAINTAINED FRIDAY AND ADDED TO THE NEW DAY
7 AS FRONT LINGERS IN AREA AND/OR ADDITIONAL UPPER WAVES TRACK
ACROSS PLAINS.

WITH THE INCREASED SHOWER/TSTM THREAT...AND ATTENDANT
CLOUDS...FRIDAY AND SATURDAY SHOULD COOL AND A GENERAL MEX/ECE
BLEND WAS MAINTAINED.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1125 PM CDT SAT AUG 30 2014

VFR CONDITIONS WITH SCATTERED TO BROKEN HIGH CLOUDS ARE FORECAST
THROUGH MID MORNING. LOW LEVEL WIND SHEAR IS LIKELY 09Z TO 15Z AT
ALL TAF SITES AS SOUTHWESTERLY LOW LEVEL JET KICKS UP TO 40 TO
50KT RANGE. GUSTY SOUTH WINDS 15 TO 25KT ARE EXPECTED AFTER 15Z
AHEAD OF A COLD FRONT MOVING INTO EASTERN NEBRASKA. THUNDERSTORMS
ARE FORECAST TO FIRE ALONG THAT FRONT AFTER 21Z...MOST LIKELY JUST
SOUTHEAST OF KOFK AREA. STRONG STORMS COULD MOVE THROUGH KOMA AND
KLNK TAF SITES AFTER 00Z.

&&

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

$$

SHORT TERM...CHERMOK
LONG TERM...CHERMOK
AVIATION...DERGAN


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