Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 292015
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
315 PM CDT FRI MAY 29 2015

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 315 PM CDT FRI MAY 29 2015

TSTM CHANCES/COVERAGE THIS EVENING THEN TIMING OF SHOWERS ENDING
LATE TONIGHT OR EARLY SATURDAY MORNING WILL BE THE MAIN FORECAST
CONCERNS IN THE SHORT TERM.

UPPER AIR CHARTS FROM 12Z SHOWED THE FOLLOWING. AT 500 MB...A TROUGH
AXIS EXTENDED FROM THE EASTERN DAKOTAS BACK INTO COLORADO. 12 HOUR
HEIGHT FALLS OF 10-30 METERS WERE NOTED. TROUGH AT 700 MB WAS IN
THE SAME GENERAL AREA. AT 850 MB...MOIST AXIS WITH DEWPOINTS OF
10 C OR GREATER EXTENDED NORTH FROM THE GULF UP INTO MISSOURI AND
ILLINOIS...THEN BACK TO THE NORTHWEST INTO MINNESOTA AND EASTERN
SOUTH DAKOTA. COOL AIR WAS NOTED FARTHER NORTH...WITH A -9 C
850 MB TEMPERATURE AT CYQD IN WESTERN MANITOBA. SURFACE ANALYSIS
EARLY THIS AFTERNOON SHOWED A COLD FRONT EXTENDING FROM NORTHWEST
WISCONSIN BACK INTO WESTERN NEBRASKA. MUCAPE VALUES WERE UP TO
AROUND 1000 J/KG ACROSS MOST OF EASTERN NEBRASKA AND SOUTHWEST
IOWA...BUT THESE VALUES DROP OFF QUICKLY BEHIND THE FRONT NEAR THE
SOUTH DAKOTA BORDER NORTHWEST OF KOFK. SFC TO 6 KM SHEAR VALUES
WERE LESS THAN 30 KNOTS.

SOME INSTABILITY WILL LINGER OVER THE AREA THIS EVENING...WITH
SCATTERED SHOWERS AND STORMS. POTENTIAL FOR SEVERE STORMS LOOKS
FAIRLY LOW. FORECAST SOUNDINGS SHOW THAT THE AIRMASS WILL
STABILIZE AS THE NIGHT GOES ON...BUT SOME SPOTTY LIGHT SHOWERS
COULD LINGER WELL BEHIND THE FRONT FROM MID LEVEL CLOUD DECK.
TROUGH AXIS SHOULD BE EAST OF OUR AREA BY AROUND 12Z SATURDAY.

WE WILL HAVE A COOL...BUT MAINLY DRY...FORECAST THROUGH THE REST OF
THE WEEKEND. 500 MB RIDGE INITIALLY OVER THE ROCKIES WILL BUILD
EASTWARD INTO THE PLAINS THROUGH MONDAY. AT THE SURFACE...COOL HIGH
PRESSURE IS FORECAST TO BUILD ACROSS THE REGION SATURDAY INTO
SATURDAY NIGHT. WINDS WILL TURN TO THE SOUTH/SOUTHEAST SUNDAY AND
FOR NOW IT APPEARS ANY PCPN WILL STAY TO OUR WEST OR NORTH.  WE
COULD SEE SOME ISOLATED TSTMS FROM SUNDAY NIGHT INTO MONDAY MORNING
WITH LOW LEVEL WARM AIR ADVECTION PATTERN IN PLACE. SHORTWAVE TROUGH
SHOULD TRACK MAINLY TO OUR NORTH...SO COVERAGE IS EXPECTED TO
BE HIGHER THERE.

LOOK FOR HIGHS SATURDAY BETWEEN 65 AND 70...68 TO 72 SUNDAY AND THEN
IN THE 70S MONDAY. SATURDAY NIGHT WILL BE THE COOLEST NIGHT...WITH
MOST LOWS IN THE LOWER OR MID 40S.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 315 PM CDT FRI MAY 29 2015

MID LEVEL RIDGE AXIS WILL FLATTEN/BUILD SOUTHEAST EARLY IN THIS
PERIOD AS A TROUGH DIGS OVER THE WESTERN UNITED STATES. RIPPLES
MOVING NORTHEAST OUT OF THIS TROUGH WILL BRING CHANCES FOR SHOWERS
AND TSTMS...ESPECIALLY FROM WEDNESDAY INTO FRIDAY. TIMING BEST
CHANCES WILL BE PROBLEMATIC. MODEL AGREEMENT STARTS TO DROP OFF
BY FRIDAY...AND SO DOES CONFIDENCE ON ANY DETAILS BY THAT TIME.
HIGHS SHOULD BE MOSTLY UPPER 70S TO MID 80S WITH LOWS IN THE UPPER
50S TO MID 60S.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1236 PM CDT FRI MAY 29 2015

VFR TO MVFR WILL BE THE PREVAILING AT ALL THREE TAF SITES FOR MUCH
OF THIS FORECAST. PERIOD. WIND SHIFT FRONT IS NOW MOVING ACROSS
NORTHEAST NEBRASKA AND WILL BE MOVING INTO WESTERN IOWA THIS
AFTERNOON. TRANSITIONAL COLD AIR BEHIND THE FRONT IS STILL MAINLY
ALONG THE NEBRASKA/SOUTH DAKOTA BORDER BUT NOW ENTERING THE
REGION. MVFR CIGS AND LIGHT RAIN ARE ASSOCIATED WITH THE COLDER
AIR. DUE TO THE STABLE NATURE OF THIS AIR MASS HAVE BACKED OFF ON
THUNDER CHANCES. STILL HAVE TEMPO OF -TSRA IN KOMA AND KLNK
BETWEEN 22Z AND 01Z BUT CONFIDENCE NOT HIGH. BEHIND FRONTAL
PASSAGE NORTHWEST WINDS WILL CONTINUE TO INCREASE REACHING THE
15G25KT RANGE AFTER 01Z.

&&

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

$$

SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...MEYER



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