Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 262000
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
300 PM CDT FRI SEP 26 2014

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 300 PM CDT FRI SEP 26 2014

TEMPERATURES AND TIMING CHANCES FOR SPOTTY PCPN WILL PROVIDE THE
MAIN FORECAST CHALLENGES IN THIS PERIOD.

CURRENT LARGE SCALE PATTERN FEATURES A TROUGH AT 500 MB EXTENDING
FROM WESTERN CANADA TO OFF THE CALIFORNIA COAST. A RIDGE STRETCHED
FROM MEXICO INTO THE GREAT LAKES REGION. A COUPLE OF VERY WEAK CUT
OFF LOWS WERE EMBEDDED IN THE RIDGE. THE LOW DOWN OVER WEST TEXAS
SHOULD HAVE LITTLE IMPACT ON OUR AREA...BUT THE ONE THAT WAS NEAR
THE BORDER OF IOWA AND MISSOURI EARLY THIS AFTERNOON IS OF SOME
CONCERN. VERY SPOTTY PCPN DID DEVELOP LAST NIGHT/EARLY THIS
MORNING OVER PARTS OF SOUTHWEST IOWA AND SOUTHEAST NEBRASKA...
SOMEWHAT IN ASSOCIATION WITH THAT LOW. A GENERAL BLEND OF THE
SHORT TERM MODELS SHOWED THAT THIS FEATURE WILL PROBABLY DRIFT
WESTWARD (RETROGRADE) INTO OUR AREA TONIGHT AND LINGER ACROSS
WESTERN IOWA INTO SUNDAY.

DID NOT INCLUDE ANY POPS FOR THIS EVENING...BUT NEXT SHIFT WILL
HAVE TO MONITOR THAT. THERE WERE A FEW ISOLATED ECHOES JUST TO OUR
EAST AS OF 3 PM. ADDED SOME LOW POPS FOR SHOWERS/THUNDERSTORMS
MAINLY OVER ABOUT THE SOUTHEAST HALF OF THE FORECAST AREA FOR
LATER TONIGHT AND INTO SATURDAY MORNING. POINT FORECAST SOUNDINGS
SHOW WEAK INSTABILITY BUT SOME POSITIVE CAPE MAINLY IN SOUTHWEST
IOWA. SPC DAY 1 OTLK ALSO HAS THAT AREA WITH POTENTIAL FOR
THUNDER. AGAIN...IF THESE OCCUR...THEY SHOULD BE VERY SPOTTY AND
PROBABLY DISSIPATE BY MID MORNING SATURDAY. FOR NOW KEPT THE REST
OF SATURDAY AND SATURDAY NIGHT DRY.

AS LOW LEVEL WARM AIR ADVECTION INCREASES ON SUNDAY...WE COULD
ALSO SEE SLIGHTLY MORE COVERAGE OF SHOWERS AND THUNDERSTORMS.
THE 12Z NAM MAY HAVE BEEN A BIT OVERDONE WITH COVERAGE AND PCPN
AMOUNTS...BUT CHANCES SEEMED HIGH ENOUGH TO ADD SOME LOW POPS
SUNDAY. OTHERWISE...WILL WILL HAVE TO WAIT UNTIL THE SYSTEM OVER
THE ROCKIES MOVES IN FOR BETTER CHANCES FOR MORE WIDESPREAD PCPN
NEXT WEEK. HIGHS SATURDAY/SUNDAY/MONDAY WILL BE MAINLY IN THE
UPPER 70S AND LOWER 80S WITH LOWS MAINLY MID 50S TO LOWER 60S.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 300 PM CDT FRI SEP 26 2014

AT THE BEGINNING OF THIS PERIOD...A CLOSED LOW OVER THE ROCKIES
SHOULD HAVE STARTED TO OPEN UP TO MORE OF A NEGATIVELY TILTED
WAVE. LARGE SCALE LIFT/FORCING FOR ASCENT INCREASES ACROSS THE
WESTERN PARTS OF THE AREA MONDAY NIGHT BUT GETS BETTER FOR ALL
OF THE FORECAST AREA ON TUESDAY. BUMPED UP POPS JUST A BIT FOR
THIS...WITH LATEST ECMWF AND GFS IN DECENT AGREEMENT ON TIMING.
FRONT WILL WEAKEN A BIT AND STALL MID WEEK.

MODEL DIFFERENCES START TO GROW BY DAY 6 AND DAY 7...WITH THE GFS
BEING A BIT WARMER THAN THE ECMWF. STAYED FAIRLY CLOSE TO AN EVEN
BLEND FOR NOW. WILL HAVE TO LINGER AT LEAST SOME LOW POPS INTO
THURSDAY NIGHT...UNTIL THE FRONTAL BOUNDARY FINALLY PUSHES OFF TO
THE SOUTHEAST. WENT DRY ON FRIDAY FOR NOW.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1220 PM CDT FRI SEP 26 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.

&&

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

$$

SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...KERN



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