FXUS63 KOAX 050833
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
233 AM CST SAT FEB 5 2011
.DISCUSSION...
SEVERAL FORECAST CONCERNS OVER THE NEXT FEW DAYS...RANGING FROM
FOG TO PRECIPITATION POTENTIAL AND TYPE...AND EVENTUAL TRANSITION
TO ANOTHER ARCTIC AIRMASS BY THE BEGINNING OF THE WEEK.
IN THE VERY SHORT TERM...PATCHY DENSE FOG HAD DEVELOPED FROM KFET
TO KTQE NORTHWARD TO KSUX. HARD TO GET A HANDLE OF THIS AS PREVIOUS
MODELS HAVE GENERALLY OVERPLAYED THE AMOUNT OF LOW LEVEL MOISTURE...
AND THUS IT APPEARS TO BE A VERY LOCAL RIVER PHENOMENON...THUS
WILL MENTION IN THE GRIDS EARLY THIS MORNING.
MEANWHILE...CLIPPER SYSTEM COMING OUT OF THE NORTHERN ROCKIES WILL
BEGIN TO IMPACT NORTHEAST NEBRASKA BY LATE MORNING AS A BAND OF
RAIN NOTED ACROSS NORTHWEST NEBRASKA AND SOUTHWEST SOUTH DAKOTA
BEGINS TO MOVE INTO THE REGION. MODELS ARE ALL SIMILAR IN THE
EASTWARD PROGRESSION...AND FEEL COMFORTABLE ENOUGH TO REMOVE
CHANCE OF PRECIP SOUTHEAST OF A KOLU TO KSUX LINE FOR THE MORNING.
PRECIPITATION TYPE WILL BE A PROBLEM...WITH WARM BUBBLE ALOFT AND
EARLY MORNING SUB FREEZING TEMPS RESULTING IN A SMALL WINDOW OF
FREEZING RAIN POTENTIAL...BEFORE COLDER AIR BEGINS TO FILER IN
ALOFT AS THE SURFACE LOW MOVES TO NORTHERN IOWA. THIS WILL ALLOW
FOR A RAIN AND SNOW MIXTURE BY AFTERNOON...ALTHOUGH WESTERN IOWA
COULD STILL SEE SOME POTENTIAL FOR SOME FREEZING RAIN OR SLEET
EARLY IN THE AFTERNOON.
SURFACE LOW THEN SHIFTS TO SOUTHEASTERN IOWA BY DAYBREAK SUNDAY AS
COLDER AIR CONTINUES TO FILTER INTO THE REGION. THERE LIKELY WILL
BE SOME LIGHT SNOW OR FLURRIES EXTENDING IN AN AXIS FROM SOUTH
DAKOTA THROUGH IOWA...AND HOW FAR SOUTH THE BAND GETS WILL BE THE
PRIMARY CONCERN. NOT EXPECTING A LARGE AMOUNT OF SNOW...ALTHOUGH A
SMALL PORTION OF NORTHEAST NEBRASKA AND NORTHWEST IOWA COULD SEE
AN INCH OR LESS.
A SECONDARY/WEAKER CLIPPER COMBINED WITH 700MB TEMPERATURES IN THE
DENDRITIC ZONE ALONG WITH A MOIST CYCLONIC SURFACE FLOW COULD KEEP
SOME LIGHT SNOW OR FLURRIES IN THE REGION SUNDAY THROUGH SUNDAY
EVENING. AGAIN...ADDITIONAL SNOWFALL AMOUNTS REMAIN LIGHT
GENERALLY UNDER ONE HALF INCH...AND SHOULD END ALTOGETHER BY
DAYBREAK MONDAY AS HIGH PRESSURE BEGINS TO TAKE CONTROL AGAIN.
BY MONDAY...THE ARCTIC AIR HAS ARRIVED AND WILL REMAIN THROUGH THE
REST OF THE WEEK. THERE IS YET ANOTHER CLIPPER COMING OUT OF THE
NORTHERN ROCKIES MONDAY AFTERNOON THROUGH TUESDAY...WITH VARYING
MODEL SOLUTIONS OF HOW FAR NORTH AND EAST THIS WILL GET. BEST
FITTING SOLUTION APPEARS TO BE THE ECMWF...WHICH SUGGESTS THAT
UPSLOPE FLOW AND VERY DRY AIR MASS COMING IN ON COLD NORTHERLY
SURFACE FLOW COULD BE LIMITING FACTOR. NORTHEAST NEBRASKA COULD
SEE SOME FLURRIES FROM THIS BY LATE MONDAY AFTERNOON...WITH MAIN
SNOW POTENTIAL ACROSS SOUTHEAST NEBRASKA MONDAY NIGHT...ALTHOUGH
GIVEN MODEL SPREADS...CONFIDENCE IS SOMEWHAT LOW OF EXACT
PLACEMENT. SMALL CHANCE OF SNOW COULD LINGER THROUGH EARLY
WEDNESDAY ALONG THE NEBRASKA AND KANSAS BORDER...BUT MAIN FOCUS IS
WELL SOUTH OF THE FORECAST AREA BY THEN.
TRIED TO TWEAK TEMPERATURES A BIT THROUGH THE WEEK TO ACCOUNT FOR
ARCTIC SURGES...WITH SUB ZERO READINGS EACH NIGHT THROUGH THURSDAY.
THERE IS HOPE THOUGH AS ZONAL FLOW RETURNS AND A WESTERLY
DOWNSLOPING FLOW SHOULD HELP TO BOOST OUR TEMPERATURES TO NEAR OR
PERHAPS JUST SLIGHTLY BELOW NORMAL BY NEXT WEEKEND.
70
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
MAIN AVIATION CONCERN IS POSSIBLE SNOW WITH CLIPPER TYPE LOW
DROPPING INTO THE LOWER 48. EXPECT VFR CONDITIONS WILL PREVAIL AT
ALL TERMINALS UNTIL ABOUT 19Z AND KOFK...22Z AT KOMA/KLNK. AFTER
THAT...MVFR CIGS WILL ACCOMPANY COLD FRONT QUICKLY PUSHING SWD
THROUGH ERN NEB. AS OF NOW IT APPEARS THAT CHANCE FOR PRECIP WILL BE
A BIT BETTER AT KOFK AND KOMA GIVEN TRACK OF SYSTEM.
HOWEVER...PRECIP CANNOT BE DISCOUNTED ALTOGETHER AT KLNK. UNTIL BULK
OF DEEP COLD AIR ADVECTION MOVES IN...EXCEPT INITIAL PRECIP TYPE AT
KOFK/KOMA WILL CONSIST OF RA/SN MIX WITH CHANGE OVER TO ALL SN
DELAYED TILL AROUND 06/00Z. MEANWHILE CHANGE TO ALL SN AT KLNK WILL
NOT COME UNTIL LATE IN THE FORECAST PERIOD TOWARD 06/06Z.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$