Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 220459
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1159 PM CDT TUE OCT 21 2014

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 353 PM CDT TUE OCT 21 2014

THE WEATHER PATTERN WILL BE UNDERGOING CHANGES DURING THE SHORT TERM
PERIODS AS AN UPPER RIDGE AXIS MIGRATES EAST AHEAD OF AN UPPER
TROUGH MOVING THRU THE ROCKIES AND ONTO THE PLAINS STATES
TONIGHT/WEDNESDAY.

FOR TONIGHT...SOUTHERLY LLVL FLOW WILL REMAIN STEADY...WITH LLVL
MOISTURE ON THE INCREASE AHEAD OF THE WESTERN TROUGH.  THE LLVL JET
STRENGTHENS TO AROUND 40KTS AND ORIENTS ALONG/EAST OF THE
MISSOURI RIVER AND INTO THE UPPER MIDWEST REGION. ALONG NOSE OF
THE JET AND IN AN AREA OF ISENTROPIC LIFT WE COULD SEE SOME LIGHT
RAIN SHOWER/SPRINKLE DEVELOPMENT ACROSS FAR EASTERN
NEBRASKA/WESTERN IOWA TOWARD DAYBREAK ON WEDNESDAY. FARTHER
WEST...A BAND OF LOW CLOUDS OR INCREASING CLOUD COVER IS EXPECTED
AHEAD OF THE APPROACHING MID LEVEL TROUGH AND SURFACE BOUNDARY.
FOG DEVELOPMENT IS NOT CLEAR CUT AND IS FOCUSED MORE SO ACROSS
CENTRAL NEBRASKA TONIGHT. WILL INCLUDE SOME PATCHY MENTION ACROSS
NORTH CENTRAL NEBRASKA FOR NOW AND MONITOR TRENDS...BUT GENERALLY
EXPECT STEADY SOUTHERLY WINDS TO PRECLUDE LOW VSBYS.

AS THE UPPER TROUGH CROSSES THE PLAINS ON WEDNESDAY...CONVECTION
WILL DEVELOP IN PRESENCE OF GOOD MID LEVEL FRONTOGENESIS WITH BAND
OF PCPN ORIENTED N/S. INSTABILITY IS STILL LOOKING PRETTY
MEAGER...GENERALLY AROUND 300 J/KG AT BEST SO ALTHOUGH ISOLATED
LIGHTNING IS POSSIBLE...NOT LOOKING FOR MUCH MORE THAN THAT.
PRECIPITABLE WATER VALUES AVERAGE AROUND ONE INCH AND DECENT
RAINFALL AMOUNTS ARE POSSIBLE BY THE TIME THE SYSTEM MOVES OUT AND
THIS IS THE BEST CHANCE FOR RAINFALL FOR SEVERAL DAYS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 353 PM CDT TUE OCT 21 2014

PRIMARY FORECAST CONCERN THROUGH THE LONG TERM REVOLVES AROUND
PRECIPITATION CHANCES AT BOTH ENDS OF THE PERIOD.

MODELS ARE IN PRETTY GOOD AGREEMENT AT THE START OF THE LONG TERM
PERIOD WITH THE OVERALL PATTERN...SHOWING THE REGION UNDER THE
INFLUENCE OF AN UPPER LEVEL TROUGH AXIS EXTENDING SOUTH FROM LOW
PRESSURE OVER CENTRAL CANADA...WITH RIDGING IN PLACE ON EITHER SIDE
OF THE TROUGH...WHILE A LARGER AREA OF LOW PRESSURE SPINS JUST OFF
THE EAST COAST. AT THE SURFACE...A WEAK FRONTAL BOUNDARY
ACCOMPANYING THIS SYSTEM IS ALSO MAKING ITS WAY EAST...BRINGING A
MORE WESTERLY COMPONENT TO THE WINDS...BUT ITS A WEAK FRONT SO NOT
LOOKING AT A NOTABLE INCREASE IN SPEEDS. FORCING ASSOCIATED WITH
THIS UPPER LEVEL TROUGH AXIS IS EXPECTED TO RESULT IN A LINE OF
MAINLY SHOWERS /A FEW RUMBLES OF THUNDER IS POSSIBLE/ SLIDING EAST
ACROSS THE CWA...AND LOOKS TO PRIMARILY AFFECT THE FIRST HALF OF THE
WEDNESDAY EVENING/OVERNIGHT PERIOD. THE HIGHER POPS REMAIN IN THE 00-
06Z TIME FRAME...WITH THINGS STARTING TO TREND DOWN THROUGH THE REST
OF THE OVERNIGHT HOURS. SOME UNCERTAINTY WITH JUST HOW QUICKLY
THINGS WILL MOVE EAST OF THE CWA...AND KEPT SOME DECENT POPS GOING
ACROSS FAR SERN PORTIONS WELL INTO THE EARLY THURSDAY MORNING
HOURS...BUT MOST MODELS AGREE WITH THINGS DRYING OUT NEAR
SUNRISE...AND DECIDED TO PULL POPS POST 12Z THURSDAY.

KEPT THE DRY FORECAST GOING INTO THE DAYTIME HOURS ON THURSDAY...BY
EVENING THE TROUGH AXIS IS EXPECTED TO HAVE SHIFTED INTO THE WI/IL
AREA...CONTINUING TO PUSH EAST BEFORE BECOMING MORE PHASED INTO THE
UPPER LEVEL LOW PRESSURE SYSTEM IN PLACE OVER THE NERN CONUS AS WE
GET INTO THE END OF THE WEEK. ACROSS THE CENTRAL CONUS...BY THE END
OF THE DAY THURSDAY MODELS ARE IN GOOD AGREEMENT SHOWING MORE
AMPLIFIED NORTHWESTERLY FLOW STARTING TO WORK ITS WAY IN FROM THE
WEST...AS RIDGING IS TRYING TO BUILD NORTH OUT OF THE DESERT
SW/MEXICO AHEAD OF ANOTHER STORM SYSTEM WELL OF THE WEST COAST. THIS
RIDGING CONTINUES TO BUILD NORTH AS WE GET INTO FRIDAY AND SHIFTS
FURTHER EAST...WITH THE AXIS BEING CENTERED THROUGH THE CENTRAL
CONUS THROUGH THE DAYTIME ON SATURDAY...KEEPING THE FORECAST A DRY
ONE.

LOOKING AHEAD TO SUNDAY AND THE FIRST PART OF THE UPCOMING WORK
WEEK...MODELS IN GOOD AGREEMENT SHOWING THE NEXT SHORTWAVE TROUGH
FINALLY MAKING ITS WAY ONTO THE WEST COAST...INTO THE ROCKIES AND
EVENTUALLY THE PLAINS. NOT EXPECTING PRECIP ON SUNDAY...THE UPPER
LEVEL FLOW WILL BE STARTING TO TURN MORE SWRLY AHEAD OF THIS NEXT
SYSTEM...BUT THE BETTER LIFT IS EXPECTED TO REMAIN OFF TO THE WEST.
BETTER CHANCES FOR PRECIP LOOK TO WORK THEIR WAY IN ON MONDAY...BUT
AS IS COMMON THIS FAR OUT...THERE ARE SOME TIMING/LOCATION
DIFFERENCES /THOUGH AT THIS TIME THEY ARE FAIRLY MINOR/ BETWEEN
MODELS WITH THE INITIAL ONSET AND EVOLUTION. AT THIS TIME...KEPT
POPS MAINLY CONFINED TO THE 12-00Z MONDAY PERIOD...WITH JUST SOME
LINGERING POPS ACROSS THE SERN CORNER OF THE CWA FOR THE MON
EVENING/OVERNIGHT PERIOD. BOTH THE ECMWF/GFS HAVE TUESDAY DRY AT
THIS POINT WITH THE TROUGH AXIS SLIDING OFF TO THE EAST.

AS FAR AS TEMPERATURES GO THROUGH THE LONG TERM PERIOD...STILL
LOOKING AT A NICE PERIOD OF HIGHS ABOVE AVERAGE FOR THIS TIME OF
YEAR /ROUGHLY THE LOWER TO MID 60S/...BEFORE COOLER AIR MOVES IN
TOWARD THE END OF THE PERIOD. WITH THE UPPER LEVEL RIDGE EXPECTED TO
BUILD INTO THE AREA LATE THIS WEEK/WEEKEND...LOOKING AT A WARMING
TREND...WITH THURS HIGHS IN THE LOWER/MID 70S AND MID/UPPER 70S FOR
FRI/SAT/SUN...BEFORE THAT NEXT SYSTEM MOVING THROUGH BRINGS HIGHS
BACK NEAR AVERAGE IN THE MID 50 TO MID 60 DEGREE RANGE FOR MON/TUES.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1145 PM CDT TUE OCT 21 2014

CLOUDS CONTINUE TO FILL IN OVER THE AREA EARLY THIS MORNING WITH A
BROKEN DECK AROUND 4-6K FEET AGL LIKELY ACROSS THE TAF SITES. THIS
SHOULD HOLD THROUGH MUCH OF THE DAY. SHOWERS WILL MOVE INTO KOFK
LATE WED AFTERNOON AND PROGRESS EASTWARD ALONG A COLD FRONT INTO
KOMA AND KLNK BY 00Z/THU. SOME ISOLATED THUNDER IS POSSIBLE...BUT
WILL LEAVE OUT OF THE TAF FOR NOW.

&&

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

$$

SHORT TERM...FAY
LONG TERM...ADP
AVIATION...KERN



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