FXUS63 KOAX 152000
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
300 PM CDT FRI APR 15 2011
.SHORT TERM...TONIGHT.
TYPE AND EXTENT OF PRECIPITATION...THEN ENDING PRECIP LATER
TONIGHT...ARE THE PRIMARY FORECAST CONCERNS.
TIGHTLY WOUND AND STACKED LOW PRESSURE SYSTEM WAS DRIFTING THROUGH
SOUTHEAST KANSAS THIS AFTERNOON. WELL DEFINED MOIST CONVEYOR BELT
WRAPPING NORTH THEN WEST ACROSS OUR CWA CONTINUED TO GENERATE
PRECIPITATION ACROSS ALL OF EASTERN NEBRASKA AND SOUTHWEST IOWA.
PRECIP HAD CHANGED TO SNOW IN NORTHEAST NEBRASKA THIS MORNING...THEN
A GRADUAL MIX THEN CHANGE TO SNOW HAD PROGRESSED ALL THE WAY TO THE
OMAHA AND LINCOLN AREAS AS OF 2 PM. SNOW ACCUMULATION REPORTS WERE
IN THE 2 TO 4 INCH RANGE IN OUR CURRENT ADVISORY AREA...GENERALLY
NORTHWEST OF A LINE FROM COLUMBUS TO WAYNE. THE HIGHEST AMOUNTS WERE
IN THE FAR NORTHWEST IN KNOX COUNTY. SEVERAL REPORTS OF QUARTER MILE
VISIBILITIES WERE NOTED FROM WAYNE TO NORFOLK AND ALBION FROM TIME
TO TIME DURING THE AFTERNOON...WITH WINDS GENERALLY IN THE 20 TO 35
MPH RANGE. ROAD REPORTS AND WEB CAMS FROM ACROSS THE SNOWY AREAS
INDICATED MAINLY SLUSHY CONDITIONS WHERE SNOW PILED UP QUICKLY...BUT
MELTING FROM TOP AND BOTTOM WAS HELPING TO LIMIT IMPACT SOMEWHAT.
LATEST WATER VAPOR IMAGERY SHOWED MID LEVEL DEFORMATION ZONE WAS
SHIFTING TO THE NORTH AND WEST THROUGH OUR NORTHWEST CWA...WITH
DRYING MID LEVEL CONDITIONS OVER THE REST OF THE AREA. THIS IS A
GOOD INDICATION THAT SNOW INTENSITY WILL SHIFT AWAY FROM OUR AREA
THE REST OF THIS AFTERNOON. RADAR TRENDS ARE SHOWING THIS AS WELL.
SO WITH DECREASING INTENSITY TRENDS AND TEMPERATURES REMAINING NEAR
OR ABOVE FREEZING...AM NOT EXPECTING MORE THAN AN INCH OR TWO OF
ADDITIONAL ACCUMULATION THROUGH THIS EVENING IN NORTHEAST NEBRASKA
WHERE ADVISORY IS IN EFFECT.
A GRADUAL CHANGE TO SNOW WILL OCCUR WITH TIME THIS EVENING AS
TEMPERATURES MORE EASILY FALL WITH SETTING SUN. HOWEVER PRECIP WILL
BE WINDING DOWN AT THAT TIME AS WELL. SO AMOUNTS ONLY UP TO AN INCH
ARE POSSIBLE IN WEST CENTRAL IOWA AND EAST CENTRAL AND SOUTHEAST
NEBRASKA. AS SYSTEM PULLS FARTHER EAST AFTER MIDNIGHT...PRECIP
SHOULD REALLY BEGIN TO DECREASE WITH ONLY OUR EASTERN HALF SEEING
SNOW OR A RAIN SNOW MIX. EXPECT PRECIP TO BE DONE ACROSS ALL OF THE
CWA BY SUNRISE SATURDAY. CLOUDS WILL BE SLOW TO CLEAR...SO WILL NOT
SEE LOWS MUCH BELOW FREEZING MOST AREAS.
STRONG WINDS WILL ALSO CONTINUE INTO THE EVENING...AND PLAN TO KEEP
WIND ADVISORY IN EFFECT FOR OUR SOUTHWEST CWA. WINDS TO THE WEST ARE
GUSTING OVER 50 MPH...BUT BREAKS IN CLOUDS ARE HELPING TO PROMOTE
MIXING THERE. EXPECT THOSE GUSTS TO RELAX A BIT WITH SUNSET...AND
GRADIENT WILL BE WEAKENING THIS EVENING AS LOW PRESSURE PUSHES EAST.
DERGAN
.LONG TERM...SATURDAY THROUGH FRIDAY.
MODELS SIMILAR IN DEVELOPING CLEARING CONDITIONS FOR THE AREA
EARLY SATURDAY MORNING WITH DIMINISHING WINDS AS SURFACE RIDGE
AXIS MOVES INTO THE AREA SATURDAY AFTERNOON. SNOWFALL IN
NORTHWESTERN PARTS OF THE CWA MAY HAVE SOME IMPACT ON TEMPERATURES
SATURDAY BUT SHOULD NOT HANG AROUND LONG WITH SOME SUN EXPECTED
BEFORE CLOUDS INCREASE AGAIN BY LATE AFTERNOON.
FAST UPPER FLOW REMAINS OVER THE REGION THROUGH MONDAY AND INTO
THE EXTENDED PERIOD WITH A WARM FRONT DEVELOPING ACROSS NORTHERN
KANSAS SATURDAY NIGHT AND REMAINING IN THE AREA INTO MONDAY. THE
COMBINATION OF THIS SURFACE BOUNDARY AND UPPER WAVES MOVING
THROUGH THE FLOW WILL ALLOW SOME CHANCE OF ADDITIONAL SHOWERS AND
THUNDERSTORMS FOR THE AREA AT LEAST THROUGH TUESDAY WHEN A
STRONGER WAVE PUSHES A COLD FRONT THROUGH THE REGION. FORECAST
LESS CERTAIN FOR WEDNESDAY THROUGH FRIDAY AS 12Z GFS AND ECMWF
SHOW SIGNIFICANT DIFFERENCES DURING THAT TIME WITH REGARD TO
STRENGTH AND TIMING OF WEATHER FEATURES. AT THIS TIME FOLLOWED HPC
GUIDANCE BUT ADJUSTMENTS LIKELY IN LATER FORECASTS.
FOBERT
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
LIFR CIGS/VSBYS IN SNOW AROUND THE KOFK AREA IS EXPECTED TO IMPROVE
TO IFR BEFORE 00Z. HOWEVER LIGHT SNOW WILL CONTINUE THROUGH 03Z TO
06Z TIME FRAME WITH CIGS REMAINING BELOW FL010 AND VSBYS 1SM TO 3SM.
FARTHER SOUTHEAST...A MIX OF LIGHT RAIN AND LIGHT SNOW WILL
GRADUALLY CHANGE TO ALL SNOW IN THE KOMA AND KLNK AREA BY 00Z.
ASSOCIATED MVFR CIGS/VSBYS WILL LOWER TO IFR THROUGH THE
AFTERNOON...WITH IFR CIGS/VSBYS CONTINUING THROUGH SNOW ENDING TIME
OF 06Z TO 09Z. VSBYS WILL IMPROVE TO VFR...BUT CIGS SHOULD HOLD
TOUGH AT ALL NEBRASKA TAF SITES THROUGH 14Z. THEN A GRADUAL
IMPROVEMENT TO MVFR THEN VFR BY 18Z SATURDAY.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR NEZ043-044-050-051-
065-066-078-088-089.
WINTER WEATHER ADVISORY UNTIL 8 PM CDT THIS EVENING FOR NEZ011-
012-016>018-030>032-042.
IA...NONE.
&&
$$