Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 190411
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1111 PM CDT FRI JUL 18 2014

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 315 PM CDT FRI JUL 18 2014

PRIMARY FORECAST CONCERNS WILL BE TEMPERATURES THROUGH THE PERIOD
AND TSTM CHANCES FROM SATURDAY NIGHT INTO MONDAY.

LARGE SCALE PATTERN AT 500 MB FEATURES FAIRLY FAST ZONAL FLOW FROM
THE NORTHERN PACIFIC INTO THE NORTHWEST UNITED STATES. THE FLOW
IN OUR AREA IS WEAKER...FROM THE NORTHWEST. A 591 DECAMETER HIGH
CENTERED OVER ARIZONA IS ALSO A PRIMARY FEATURE. THINGS WILL
TRANSITION INTO SUNDAY...WITH THE CENTER OF THE HIGH STRENGTHENING
AND MOVING EAST INTO SOUTHEAST NEW MEXICO. AN EXTENSION OF THIS
HIGH WILL BUILD TOWARD OUR AREA BY SUNDAY...WHILE A TROUGH DEVELOPS
FROM WESTERN CANADA SOUTHWARD ALONG 120-130 DEGREES WEST LONGITUDE.
HEIGHTS SHOULD CONTINUE TO RISE THROUGH MONDAY AS THE WESTERN
TROUGH STRENGTHENS AND THE CENTER OF THE NEW MEXICO RIDGE
INTENSIFIES AND EXPANDS INTO MONDAY. WE WILL GRADUALLY SEE AN
INCREASE IN LOW LEVEL MOISTURE AND A DECREASE IN STABILITY. 850 MB
DEWPOINTS WERE MOSTLY IN THE SINGLE DIGITS LOCALLY (BUT UP TO
AROUND 10 C IN CENTRAL NEBRASKA). THESE SHOULD INCREASE TO THE MID
TEENS C ACROSS OUR WESTERN ZONES BY SATURDAY EVENING AND THEN
EXPAND EASTWARD SATURDAY NIGHT. 700 MB TEMPERATURES WILL ALSO BE
WARMING THROUGH THE PERIOD...WHICH WILL TRY TO CAP OFF BOUNDARY
LAYER BASED CONVECTION BY SUNDAY. FORECAST SOUNDINGS SHOW LAPSE
RATES INITIALLY RATHER LOW BUT INCREASING TO AROUND 7 DEGREES C IN
THE 700-500 MB LAYER BY 21Z SATURDAY IN NORTHEAST NEBRASKA. THESE
VALUES CONTINUE TO INCREASE SATURDAY NIGHT TO AROUND 7 DEGREES C
FOR MOST OF THE LOCAL AREA (AND TO AROUND 7.5 DEGREES C TOWARD
CENTRAL NEBRASKA).

TONIGHT...THE CLOUDS IN THE 3000-8000 FOOT LAYER SHOULD GRADUALLY
DECREASE. IT SEEMS THAT LOW CLOUDS COULD REFORM OVERNIGHT THOUGH
TO OUR WEST AS 925 MB MOISTURE AXIS SHOULD EXTEND FROM WESTERN
KANSAS INTO CENTRAL AND SOUTHWEST NEBRASKA BY SUNRISE. LOWS THIS
MORNING WERE MOSTLY MID 50S TO AROUND 60. DUE TO SLIGHTLY
STRONGER SOUTHERLY FLOW AND SOME LOW LEVEL WARM AIR ADVECTION...WE
LOOK FOR LOWS TONIGHT MAINLY IN THE LOWER 60S OR AROUND 60.

SATURDAY...LOOK FOR BREEZY CONDITIONS THROUGH THE DAY AS STRONGER
WINDS ALOFT MIX DOWN. 850 MB TEMPERATURE FORECASTS AND MOS GUIDANCE
SUGGEST HIGHS MAINLY IN THE 80S (WARMEST WEST AND COOLEST EAST)...
WHICH WAS VERY SIMILAR TO EARLIER FORECASTS.

SATURDAY NIGHT...INFLUX OF DEEPER MOISTURE (PRECIPITABLE WATER
VALUES INCREASING TO 1.50 OR HIGHER)...A WEAK SHORTWAVE TROUGH AND A
MODEST LOW LEVEL JET SHOULD BE ENOUGH TO GO WITH A SMALL CHANCE OF
THUNDERSTORMS SPREADING EAST. MAX LOW LEVEL JET AXIS AROUND 1 KM AGL
DOES STAY MOSTLY TO OUR WEST THOUGH...OTHERWISE MAY HAVE GONE WITH
SLIGHTLY HIGHER POPS.

SOME STORMS COULD LINGER INTO MID MORNING SUNDAY...OTHERWISE THE
ATMOSPHERE WILL PROBABLY BECOME CAPPED OFF BY AFTERNOON AS 700 MB
TEMPERATURES WARM INTO THE 12-16 C RANGE. LOOK FOR HIGHS SUNDAY
MOSTLY 90 TO 95 BUT MAY BE A BIT COOLER IN SOUTHWEST IOWA. HEAT
INDEX VALUES SHOULD TOP OUT FROM 98 TO 103 IN EASTERN NEBRASKA
AND MOSTLY 90S IN SOUTHWEST IOWA.

DECIDED TO KEEP POPS AT 14 OR LESS FOR SUNDAY NIGHT INTO MONDAY...
WITH VERY WARM 700 MB TEMPERATURES IN PLACE. THIS MAY NEED TO BE
ADJUSTED AS WE MOVE FORWARD...BECAUSE FORECAST SOUNDINGS SHOW
SOME ELEVATED INSTABILITY ABOVE 600 MB IN DURING THAT PERIOD.
HIGHS SHOULD BE 1 TO 3 DEGREES WARMER MONDAY WITH MAX HEAT INDEX
VALUES REACHING 100 TO 105.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 315 PM CDT FRI JUL 18 2014

GENERALLY FAVORED A BLEND OF THE 12Z GFS AND 12Z ECMWF IN THE
EXTENDED PERIOD...WITH INCREASINGLY HIGHER WEIGHT GIVEN TO THE ECMWF
TOWARD THURSDAY AND FRIDAY. THE OPERATIONAL GFS SEEMED TO BULLISH
WITH A SHORTWAVE ACROSS IDAHO AND WESTERN MONTANA BY 12Z THURSDAY.

TEMPERATURES WILL START OUT WARM (HIGHS IN THE LOWER TO MID 90S) BUT
COOL SOME THROUGH THE WEEK AS 850 MB TEMPERATURES AND 1000-500 MB
THICKNESS VALUES DECREASE.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1110 PM CDT FRI JUL 18 2014

VFR CONDITIONS ARE EXPECTED AT TAF SITES THROUGH 20/06Z AS
HIGH PRESSURE CONTINUES FROM LOWER MISSOURI VALLEY INTO GREAT
LAKES REGION. PATCHES OF STRATO CUMULUS WILL MOVE ACROSS MOSTLY
SOUTHEAST NEBRASKA TONIGHT BUT ANY CEILINGS SHOULD BE AT OR ABOVE
FLO040. THE THREAT OF MVFR CIGS DEVELOPING OR MOVING ACROSS TAF
SITES SATURDAY MORNING SEEMED PRETTY LOW AND THUS NO MENTION WAS
MADE IN 06Z FORECAST.

&&

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

$$

SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...CHERMOK



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