FXUS63 KOAX 080754
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
254 AM CDT FRI JUL 8 2011
.DISCUSSION...
AFTER A DRY DAY TODAY...APPARENTLY...INCREASING PRECIPITATION
CHANCES RETURN BEGINNING LATE TONIGHT AND SPREADING FROM NW TO SE
ACROSS AT LEAST THE NRN HALF OF THE FORECAST AREA. MAIN CHANGE TO
FORECAST WAS TO INCREASE POPS A LITTLE ACROSS MAINLY THE NORTHERN
ZONES TONIGHT...SATURDAY AND SUNDAY NIGHTS. OF GENERAL
OBSERVATION...GFS IS SUSPECT AT TIMES WITH POSSIBLE CONVECTIVE
FEEDBACK SHOWING UP PERIODICALLY...ESPECIALLY AFTER SUNDAY.
UPPER TROUGH THAT WILL BE AIDING IN BRINGING THESE INCREASED
PRECIP CHANCES TO THE AREA WAS PUNCHING FROM NERN WA TOWARD SE
BC/SRN ALBERTA ACCORDING TO OVERNIGHT SATELLITE IMAGERY. THIS
SYSTEM WILL EVENTUALLY SEND A COLD FRONT INTO ERN NEBRASKA/WRN IA
VICINITY AS IT TRACKS ACROSS SRN CANADA AND THEN TO NORTHEAST OF
THE GREAT LAKES REGION. WITH AN INCREASING LOW LEVEL JET AHEAD OF
THE FRONT TONIGHT...ACTIVITY THAT DEVELOP WRN HIGH PLAINS MAY HOLD
TOGETHER AS IT MOVES TOWARD NERN NEBRASKA...THUS THE INCREASED
POPS THAT AREA TONIGHT. FRONT GETS CLOSER TO NERN NEBRASKA LATE
SATURDAY NIGHT AND GRADUALLY PUSHES ACROSS THE AREA SUNDAY
NIGHT/MONDAY. SOME DISAGREEMENT ON HOW MUCH A LOW LEVEL JET WILL
ASSIST CONVECTION SPREADING/DEVELOPING SE SAT NIGHT WITH 12Z ECMWF
MORE SUPPORTIVE ACROSS NERN/ECNTRL ZONES WITH OPERATIONAL GFS/NAM
AND LATEST SREF SOMEWHAT SUPPORTIVE SW TO NERN ZONES IN EVENING
BUT WITH A WEAKENING LOW LVL WIND FCST BY MORNING. BASED ON
SREF/12Z ECMWF BOOSTED POPS SAT NIGHT ALONG/N OF HIGHWAY 30. WITH
STRONGER HEATING EXPECTED SUNDAY INCREASING AVAILABLE LINGERING
CAPE SUNDAY NIGHT...PLUS BOUNDARY AIDING IN LOW LEVEL CONVERGENCE
FARTHER SOUTH INTO FORECAST AREA...APPEARS HIGHEST POPS WILL
PERSIST IN SUNDAY NIGHT/MONDAY PERIOD PER PREVIOUS FORECAST.
ALTHOUGH DID BOOST NRN ZONES SLIGHTLY BASED ON CONSENSUS SUPPORT
FROM PREVIOUSLY MENTIONED MODELS. WITH PRECIPITABLE WATER VALUES
EXPECTED TO INCREASE TO AROUND 2 INCHES BASED ON GFS/NAM...AND THE
FACT THAT SHOWERS/TSTMS WILL BE MOVING AWAY FROM STRONGER UPPER
WINDS AND PARALLELING E-W FRONT...HEAVY RAIN COVERING A LARGER
AREA WILL BE POSSIBLE. THIS WOULD ESPECIALLY BE SO BY SUNDAY
NIGHT AS BOUNDARY SETTLES IN...BUT THEN PERSISTING INTO MIDWEEK IF
BOUNDARY PERSISTS PER 00Z GFS...AS SUBTROPICAL FLOW AND POSSIBLE
WAVES ROTATE AROUND UPPER RIDGE. HEAVY RAIN POTENTIAL IN DAY 3 AND
BEYOND PERIODS WILL HAVE TO BE ASSESSED IN LATER FORECASTS.
MADE LITTLE CHANGES TO TEMPERATURES THROUGH MUCH OF THIS FORECAST.
MAYBE INCREASED MAX TEMPS A BIT TODAY/SATURDAY BASED ON A SEVERAL
MORES...MORE SUNSHINE MORE OF THE DAY AND MORE OF SRLY COMPONENT
TO LOW LEVEL WINDS. WITH POSSIBLE WIDESPREAD CONVECTION NRN ZONES
SAT NGT/SUNDAY NIGHT LOWERED MIN TEMPS TO NEAR 70 THOSE AREAS.
WITH WARM H85 TEMPERATURES FORECAST TO BE PRESENT...THOSE AREAS
THAT REMAIN OR BECOME ABSENT OF CONVECTIVE DEBRIS WILL STRONGLY
RECOVER AND A WIDE RANGE IN MAX TEMPERATURES SOMEWHERE IN OUR VICINITY
IF NOT ACROSS OUR FORECAST AREA COULD OCCUR. THUS DUE TO THIS
UNCERTAINTY MADE LITTLE CHANGES TO MAX TEMPERATURES SUNDAY AND
BEYOND...ESPECIALLY NRN ZONES.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
VFR CONDITIONS ARE FORECAST AT ALL THREE TAF SITES THROUGH FORECAST
PERIOD EXCEPT FOR A BRIEF EARLY MORNING POSSIBILITY OF IFR
VISIBILITY DUE TO FOG. BEST CHANCE FOR IFR FOG WOULD BE IN THE 10Z
TO 13Z TIME PERIOD. SURFACE HIGH PRESSURE OVER THE REGION COMBINED
WITH LIGHT AND VARIABLE WIND WILL CONTRIBUTE TO THE FAVORABLE
CONDITIONS FOR EARLY MORNING FOG DEVELOPMENT. KOMA SITTING NEXT TO
FLOODING MISSOURI RIVER PROBABLY HAS BETTER CHANCE THAN KLNK AND
KOFK. AFTER 14Z EXPECT WHAT FOG DOES DEVELOP TO BURN OFF FOLLOWED
BY VFR CONDITIONS.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
CHERMOK/MEYER