FXUS63 KOAX 131010
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
409 AM CST SUN FEB 13 2011
.DISCUSSION...
MAIN FORECAST PROBLEM IN THE SHORT TERM ARE TEMPERATURES AND WINDS.
AT 08Z...THE AREA IS JUST NORTH OF A SURFACE RIDGE WITH
SOUTHWESTERLY FLOW ACROSS MUCH OF NEBRASKA AND IOWA. ANOTHER MILD
DAY WITH WARMER TEMPERATURES FOR THE SOUTHERN TWO THIRDS OF THE CWA
AS AT 850 MB MODELS ARE SHOWING TEMPERATURES AROUND 12 TO 14 DEGREES
C. BY LATE AFTERNOON...A COLD FRONT WILL MOVE THROUGH THE AREA
WHICH WILL ALLOW FOR A COOLER MONDAY.
WINDS ARE EXPECTED TO INCREASE LATER THIS AFTERNOON AND TONIGHT AS
THE COLD FRONT MOVES THROUGH. WINDS IN THE NORTHWEST PART OF THE CWA
MAY APPROACH WIND ADVISORY CRITERIA. BUFKIT SOUNDINGS FROM THE NAM
AND GFS SHOW 50 TO 60 KT AROUND 900 MB AT NELIGH. HOWEVER STRONGEST
WINDS ALOFT START OCCURRING AFTER 00Z AND THERE IS A STRONG
INVERSION FROM THE SURFACE TO ABOUT 975 MB. THERE IS SOME QUESTION
AS HOW MUCH OF THAT 900 MB WIND CAN MIX DOWN TO THE SURFACE.
BECAUSE OF THIS UNCERTAINTY...HAVE OPTED NOT TO ISSUE A WIND
ADVISORY FOR THE NORTHWESTERN PORTION OF THE CWA.
BY TUESDAY...SURFACE FLOW STARTS RETURNING MORE SOUTHERLY AND
TEMPERATURES WILL BEGIN TO WARM UP AGAIN. DEWPOINTS WILL ALSO
INCREASE BEGINNING TUESDAY NIGHT. THE GREATEST INCREASE IN LOW LEVEL
MOISTURE IS FORECAST TO BE OVER SOUTHEAST NEBRASKA AND SOUTHWEST
IOWA WHERE FOG AND SOME DRIZZLE IS POSSIBLE...ESPECIALLY DURING THE
EVENING PERIODS. IT IS UNCLEAR AT THIS TIME...WHETHER THIS WILL
IMPACT HIGH TEMPERATURES ON WEDNESDAY AND THURSDAY. TEMPERATURES
CONTINUE WARM THROUGH FRIDAY. BY FRIDAY NIGHT ...A COLD FRONT MOVES
THROUGH THE AREA WITH A MUCH COLDER AIR MASS ACROSS THE AREA ON
SATURDAY.
SMITH
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
WINDS AND LOW LEVEL WIND SHEAR WILL BE THE PRIMARY CONCERNS FOR THE
AVIATION FORECAST.
ANOTHER MILD DAY IS EXPECTED TODAY WITH SOUTHWEST WINDS AT 10 TO
20KTS. H900 MILLIBAR WINDS WILL BE FROM SOUTHWEST-WEST 30 TO 45KTS
TODAY...HOWEVER LATE THIS AFTERNOON A COLD FRONT WILL BE MOVING IN
WITH MUCH STRONGER H900 MILLIBAR WINDS OF 50-60KTS. WITH A STEEP
INVERSION IN PLACE...THIS WILL RESULT IN LOW LEVEL WIND SHEAR.
MIXING WILL BE THE KEY TO THE LATE AFTERNOON AND OVERNIGHT FORECAST.
THE SHORT RANGE MODELS DO NOT MIX THESE STRONG WINDS DOWN TO THE
SURFACE AND THIS WILL HAVE TO BE WATCHED. POSITIVES ARE THE WINDS
BEING FAIRLY UNI-DIRECTIONAL WITH SOME COLD ADVECTION...THE
WEAKENING INVERSION...AND STEEPER LAPSE RATES. NEGATIVES ARE THE
INVERSION...SNOW COVER AND TIME OF DAY. THE SREF SHOWS THE HIGHER
PROBABILITY FOR THE 25KT/34KT SURFACE WINDS FROM NORTHEAST NEBRASKA
NORTHWARD INTO THE DAKOTAS...MINNESOTA AND IOWA FROM 21Z TO 09Z. FOR
NOW WILL INCREASE THE WINDS AT KOFK...BUT WILL KEEP THEM BELOW
ADVISORY CRITERIA. HIGH CLOUDS WILL BE ON THE INCREASE TODAY AND
WILL CONTINUE WITH VFR CONDITIONS.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$