FXUS63 KOAX 190815
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
315 AM CDT SAT MAR 19 2011
.DISCUSSION...
PRECIPITATION CHANCES OVER THE NEXT FEW DAYS WILL PROVIDE THE MAIN
FORECAST CHALLENGES.
WATER VAPOR SATELLITE IMAGERY EARLY THIS MORNING SHOWED AN IMPRESSIVE
MID TROPOSPHERIC TROUGH OVER THE EASTERN PACIFIC AND THE FAR WESTERN
UNITED STATES. WEAK 500 MB HEIGHT RISES OCCURRED LAST EVENING AND
THIS TREND HAS CONTINUED OVERNIGHT. SURFACE ANALYSIS AT 08Z INDICATED
HIGH PRESSURE FROM MINNESOTA AND IOWA DOWN INTO MISSOURI...WHILE WEAK
LOW PRESSURE WAS OVER THE HIGH PLAINS. DEWPOINTS LOCALLY WERE IN THE
UPPER 20S AND LOWER 30S. LATEST REGIONAL RADARS SHOWED SOME LIGHT
PRECIPITATION SPREADING ACROSS PORTIONS OF WESTERN AND CENTRAL SOUTH
DAKOTA. AS THE HIGH PRESSURE MOVES EAST...SOUTHERLY WINDS SHOULD
INCREASE AND BRING LOW LEVEL MOISTURE NORTHWARD. GENERALLY USED A
BLEND OF MODEL SOLUTIONS FOR THE FORECAST THROUGH MID WEEK. THE 00Z
GFS WAS MAINLY USED FOR DETAILS TODAY AND TONIGHT. 00Z ECMWF MODEL
SEEMED A BIT TOO WET FOR OUR AREA PRIOR TO 18Z. LATEST RUNS OF THE
HRRR MODEL KEPT OUR AREA MAINLY DRY TOO THROUGH 19Z. AFTER THAT...
RAIN CHANCES SHOULD BE ON THE INCREASE AS 850 MB MOISTURE CONTENT
RISES AND THE ATMOSPHERE BECOMES MORE UNSTABLE. 00Z GFS MODEL HAD
850 MB LIFTED INDICES DROPPING TO LESS THAN ZERO ACROSS ABOUT THE
SOUTHERN HALF OF THE FORECAST AREA BY EARLY EVENING. RAISED HIGHS A
BIT FOR TODAY...INTO THE MID AND UPPER 50S.
LOW LEVEL MOISTURE CONTINUES TO INCREASE THIS EVENING AND REMAINS
ADEQUATE FOR SHOWERS AND ISOLATED THUNDERSTORMS OVERNIGHT. BUMPED
PRECIPITATION CHANCES UPWARD INTO LIKELY CATEGORY FOR TONIGHT...
WITH LOWS STAYING IN THE 40S. A FAIRLY COMPLEX LOW PRESSURE SYSTEM
IS EXPECTED TO TRACK ACROSS THE PLAINS SUNDAY...WITH A CONTINUED
CHANCE FOR SHOWERS AND ISOLATED THUNDERSTORMS. BEST CHANCES WILL
BE IN THE MORNING. BY LATE SUNDAY...A COLD FRONT SHOULD STRETCH FROM
WESTERN WISCONSIN ACROSS IOWA AND INTO SOUTHEAST NEBRASKA...WITH
WEAK HIGH PRESSURE OVER SOUTH DAKOTA. THAT FRONT SHOULD BE THE
FOCUS FOR SHOWERS AND THUNDERSTORMS SUNDAY NIGHT...MAINLY ACROSS
SOUTHEAST NEBRASKA. THE BOUNDARY SHOULD LIFT NORTHWARD AS A WARM
FRONT MONDAY AND EARLY TUESDAY. BEST PRECIPITATION CHANCES WILL
BE NORTH OF THE FRONT.
COLDER AIR WILL MOVE INTO THE AREA AS WINDS SHIFT TO THE NORTHWEST
BEHIND THE DEPARTING LOW PRESSURE SYSTEM WEDNESDAY. ADDED A SMALL
CHANCE FOR LIGHT RAIN AND LIGHT SNOW ACROSS THE NORTHERN ONE THIRD
OF THE FORECAST AREA FOR WEDNESDAY. NO OTHER SIGNIFICANT CHANGES
WERE MADE BEYOND THAT.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
THE MAIN CONCERNS FOR THE AVIATION FORECAST WILL BE THE WIND AND
LOW LEVEL WIND SHEAR...THEN POTENTIAL FOR PRECIPITATION AND
MVFR/IFR CEILINGS.
SURFACE HIGH PRESSURE OVER THE REGION WILL RETREAT TO THE EAST AND
THIS WILL ALLOW SURFACE WINDS TO INCREASE FROM THE SOUTH AS LOW
PRESSURE DEVELOPS OVER THE ROCKIES. SOUTH TO SOUTHEAST WINDS WILL
STEADILY INCREASE TODAY TO 15 TO 22 KNOTS SUSTAINED WITH HIGHER
GUSTS 25 TO 30 KNOTS. SURFACE WINDS SHOULD SETTLE DOWN TO UNDER
15 KNOTS AFTER 00Z. THE SHORT TERM MODELS DO SHOW THE POTENTIAL
FOR LLWS TODAY WITH AREAS OF 925 MB WINDS OF 30 TO 40 KNOTS.
TONIGHT 925 MB WINDS INCREASE TO 35-50 KNOTS.
AS WARM AIR AND INCREASING MOISTURE RETURNS TO THE REGION...THERE IS
A CHANCE FOR SPRINKLES OR SHOWERS. THE FIRST SHORTWAVE TROUGH IS
SUBTLE AND HAS LIFT MOVING THROUGH THE AREA BETWEEN 15-19Z
ALTHOUGH THERE MAY BE ENOUGH DRIER AIR IN THE LOWER LEVELS TO
HINDER THE PRECIPITATION FROM REACHING THE GROUND. WITH A SURGE IN
LOW LEVEL MOISTURE DURING THE EVENING...WILL INCLUDE LOWER MVFR
CEILINGS AND VISIBILITIES AFTER 00Z AND THE POTENTIAL FOR
-SHRA/-TSRA/DRIZZLE. THERE COULD BE SOME IFR CEILINGS/VISIBILITIES
AS WELL.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
DISCUSSION...MILLER
AVIATION...ZAPOTOCNY