Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 282115
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
315 PM CST WED JAN 28 2015

.SHORT TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 315 PM CST WED JAN 28 2015

THE CHANCE OF PCPN ON THE WEEKEND AND TEMPERATURES THROUGH THE
PERIOD WILL PROVIDE THE MAIN FORECAST CHALLENGES.

A COUPLE OF SHORTWAVE TROUGHS WILL MOVE ACROSS THE REGION DURING THE
OVERNIGHT HOURS. 12 HOUR HEIGHT FALLS AT 12Z AT 500 MB WERE AS HIGH
AS 100 METERS OVER WYOMING. THIS WAVE WILL MOVE EASTWARD THROUGH
EARLY TONIGHT WITH ANOTHER WAVE DROPPING SOUTHEAST FROM THE DAKOTAS
AFTER MIDNIGHT. MOISTURE PROFILES ARE NOT SATURATED...BUT THERE
MAY BE ENOUGH MOISTURE FOR SOME SPRINKLES OR LIGHT SHOWERS IN OUR
NORTHERN AND EASTERN COUNTIES. WILL NEED TO WATCH SURFACE
TEMPERATURES SINCE PCPN WILL BE FALLING AS LIQUID AND IF IT DROPS
BELOW FREEZING IT MAY CAUSE SOME VERY LIGHT SPOTTY ICING. WINDS
WILL ALSO INCREASE LATER TONIGHT AS LOW PRESSURE AT THE SURFACE
TRACKS ACROSS IOWA AND INTO NORTHEAST ILLINOIS BY DAYBREAK.

TIGHTENING PRESSURE GRADIENT AND DOWNWARD MOMENTUM TRANSFER (GFS
SHOWS 925 MB WINDS UP TO AROUND 40 OR 45 KNOTS OVERNIGHT) WILL BE
THE MAIN REASONS FOR THE STRONG WINDS. THESE MAY NOT BE CONSTANTLY
AT ADVISORY NUMBERS ALL NIGHT...BUT FEEL AT LEAST A COUPLE OF
PERIODS OF STRONG WINDS WILL OCCUR. WILL GO AHEAD AND ISSUE A
WIND ADVISORY FOR MOST OF OUR FORECAST AREA STARTING MID EVENING
IN NORTHEAST NEBRASKA THEN SPREADING THAT SOUTHEAST WITH TIME.

THE STRONG NORTHWEST WINDS WILL BRING IN COOLER AIR FOR THURSDAY.
THESE WINDS SHOULD REMAIN FAIRLY STRONG IN THE MORNING BUT DECREASE
THROUGH THE AFTERNOON AS SURFACE RIDGE AXIS BUILDS INTO THE AREA
BY THURSDAY EVENING. WENT WITH HIGHS MOSTLY IN THE UPPER 30S AND
LOWER 40S NORTH...LOWER AND MID 40S SOUTH. SOUTHERLY WINDS ARE
FORECAST TO INCREASE FRIDAY AS THE RIDGE MOVES EAST LATE THURSDAY
NIGHT INTO FRIDAY MORNING. WILL BOOST HIGHS A BIT FOR FRIDAY...TO
THE LOWER AND MID 40S BUT EVEN WARMER READINGS APPEAR POSSIBLE
IN OUR SOUTHWEST ZONES. DECIDED NOT TO BE TOO OPTIMISTIC AT THIS
TIME.

THE OPERATIONAL RUNS OF THE 12Z GFS AND 12Z ECMWF HAVE CHANGED IN
REGARDS TO POSSIBLE PCPN AMOUNTS FOR THE WEEKEND. THE 12Z GFS
ENSEMBLE AND THE 15Z SREF STILL INDICATE SOME POTENTIAL FOR LIGHT
RAIN/SNOW. FOR OUR AREA...IN GENERAL...EXPECT THAT THE MAIN
FORCING AND MOISTURE WILL STAY TO OUR SOUTH SATURDAY INTO SATURDAY
NIGHT. THIS WILL BE ADJUSTED (IF NEEDED) AS WE GET CLOSER. THE
MODELS MAY DEVIATE MORE FROM RUN TO RUN OVER THE NEXT FEW DAYS.
THIS VARIANCE WILL BE AT LEAST PARTIALLY DUE TO THE COMPLEX FLOW
THAT WILL DEVELOP OVER THE NORTHERN PACIFIC...WHICH IS NOT A HIGH
DENSITY DATA AREA FOR UPPER AIR OBSERVATIONS IN MOST CASES.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 315 PM CST WED JAN 28 2015

ANOTHER WAVE WILL DROP DOWN ACROSS THE DAKOTAS TOWARD THE CENTRAL
PLAINS FOR SATURDAY NIGHT...BUT THIS MAY HAVE LARGER IMPACTS IN
SOUTHERN MINNESOTA AND NORTHERN IOWA.

PCPN CHANGES WILL BE DECREASING SUNDAY AND SUNDAY NIGHT...AND OUR
TEMPERATURES SHOULD AS WELL. COLD HIGH PRESSURE WILL BE OVER THE
EASTERN DAKOTAS BY NOON SUNDAY...THEN THAT SHOULD MOVE INTO IOWA
AND MISSOURI BY MONDAY MORNING.

SYSTEM AMPLIFICATION SEEMS POSSIBLE BASED ON THE NORTHWEST FLOW
PATTERN FOR SUNDAY...SO WILL NEED TO WATCH THE WAVE SHOWN IN THE
NORTHERN STREAM ON SUNDAY. THE CANADIAN MODEL EVEN BRIEFLY SHOWS
A CLOSED LOW AT 500 MB NEAR THE SOUTH DAKOTA/MINNESOTA BORDER ON
SUNDAY.

OTHERWISE WILL WILL BE MAINLY UNDER THE INFLUENCE OF COOL NORTHWEST
FLOW EARLY NEXT WEEK. HIGHS WILL BE MUCH BELOW NORMAL SUNDAY INTO
MONDAY...THEN SHOULD TREND CLOSER TO NORMAL FOR TUESDAY/WEDNESDAY.
KEPT A SMALL CHANCE OF LIGHT SNOW GOING FOR TUESDAY.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1127 AM CST WED JAN 28 2015

VFR CONDITIONS ARE EXPECTED EARLY IN THE PERIOD WITH LIGHT
SOUTHEAST WINDS INITIALLY. A COLD FRONT WILL DROP SOUTH THIS
EVENING TURNING WINDS TO THE NORTHWEST. THESE WILL INCREASE TO
AROUND 25 KTS WITH GUSTS UP TO NEAR 35 KTS POSSIBLE OVERNIGHT. IN
ADDITION...MVFR CIGS ARE EXPECTED TO DEVELOP AFTER 06Z.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CST THURSDAY FOR
     NEZ045-050>053-065>068.

     WIND ADVISORY FROM 11 PM THIS EVENING TO 7 AM CST THURSDAY FOR
     NEZ015-030>034-042>044.

     WIND ADVISORY FROM 9 PM THIS EVENING TO 6 AM CST THURSDAY FOR
     NEZ011-012-016>018.

IA...WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CST THURSDAY FOR
     IAZ055-056-069-079-080-090-091.

     WIND ADVISORY FROM 11 PM THIS EVENING TO 7 AM CST THURSDAY FOR
     IAZ043.

&&

$$

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



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