000
FXUS63 KOAX 081725
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1125 AM CST SUN DEC 8 2013

.AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.

LIGHT TO MODERATE SNOW CONTINUES AT ALL SITES...BUT VIS AND
CEILINGS SHOULD GRADUALLY IMPROVE THROUGH THE AFTERNOON.
KOMA MAY HOLD ON TO SNOW UNTIL AT LEAST AROUND 00Z...BUT OTHER
SITES SHOULD TAPER TO FLURRIES BEFORE THEN. OVERNIGHT...CEILINGS
SHOULD DECREASE...WHILE WINDS WILL INCREASE OUT OF THE NORTHWEST.
HAVE ONLY BROUGHT WINDS ABOVE 12KT AT KOFK...WITH KOMA/KLNK AT
AROUND 10KT...AND WINDS SHOULD BEING TO DECREASE BY AROUND 18Z
MONDAY.

MAYES

&&

.PREV DISCUSSION... /ISSUED 854 AM CST SUN DEC 8 2013/

DISCUSSION...
HAVE UPDATED THE FORECAST...WITH THE BIGGEST CHANGE BEING THE
ADDITION OF PAWNEE AND RICHARDSON COUNTIES TO THE ADVISORY.
MODERATE SNOWFALL IS ONGOING THERE...AND THE POTENTIAL IS JUST AS
HIGH THERE FOR 2-3 INCHES OF SNOW AS MANY OTHER AREAS OF THE CWA.
ACTUALLY REDUCED POPS IN NORTHEAST NEB FOR A SHORT PERIOD THIS
LATE MORNING/EARLY AFTERNOON...WHERE THERE ARE LITTLE MORE THAN
FLURRIES NOW. ADJUSTED SNOW TOTALS DOWNWARD UP THERE...AND UPWARD
IN SOUTHEAST NEB. ALSO UPDATED TEMPERATURE AND DEWPOINT
TRENDS...AS TEMPS DID NOT FALL FAR OVERNIGHT AND HAVE BEEN STEADY
TO RISING.

MAYES

PREV DISCUSSION... /ISSUED 322 AM CST SUN DEC 8 2013/

DISCUSSION...
DURATION/COVERAGE/AMOUNTS OF SNOW THROUGH THIS EVENING ARE THE
PRIMARY FORECAST CHALLENGES.

SNOW DEVELOPED SATURDAY EVENING ACROSS MUCH OF SOUTHERN NEBRASKA
INCLUDING SOUTHEAST NEBRASKA...AND HAD SPREAD NORTH TO THE PLATTE
RIVER AND THE OMAHA METRO BY MIDNIGHT. THIS WAS SEVERAL HOURS
EARLIER THAN MODELS SHOWED 24 HOURS AGO WHEN THEY WERE PAINTING
SIGNIFICANT BOUNDARY LAYER DRY AIR THAT WOULD NOT BE OVERCOME UNTIL
AFTER MIDNIGHT FOR ALL BUT THE WESTERN CWA. ENHANCED LIFT IN RIGHT
ENTRANCE REGION OF UPPER JET OVERCAME THIS DRY AIR RATHER QUICKLY AS
RADAR RETURNS BLOSSOMED RAPIDLY SATURDAY EVENING IN SOUTH CENTRAL
THEN SOUTHEAST NEBRASKA. 00Z MODELS WERE NOT HANDLING THIS AREA OF
PRECIP WELL AT ALL...INSTEAD FOCUSING ON NORTHERN NEBRASKA BY 06Z.
HOWEVER MESOSCALE MODELS HRRR AND RAP WERE AT LEAST OFFERING BETTER
SOLUTIONS COMPARED TO CURRENT TRENDS.

UPPER TROUGH REMAINED WELL TO OUR WEST THIS MORNING...WITH BASE OF
TROUGH AXIS NEARING THE FOUR CORNERS REGION AT 08Z. A COUPLE OF
SHORTWAVES WERE NOTED IN WATER VAPOR IMAGERY...ONE ROUNDING BASE OF
TROUGH THAT WAS SHOWING ENHANCEMENT IN SOUTHERN ARIZONA...AND A
SECOND WAS SPINNING THROUGH CENTRAL COLORADO. THE FIRST SHORTWAVE
SUGGESTS A STRONG JET SEGMENT THAT WAS NOT HANDLED WELL BY
MODELS...AND EXTRAPOLATION PUTS THE LEFT EXIT REGION OF THAT JET
INTO NEBRASKA LATER THIS MORNING. THIS WILL AGAIN ENHANCE LIFT IN
OUR SOUTHERN/CENTRAL CWA. AND THE COLORADO VORT/SHORTWAVE IS PROGGED
TO WORK EAST INTO NEBRASKA THIS AFTERNOON BEFORE EXITING TO OUR EAST
BY 06Z. AHEAD OF BOTH SHORTWAVES WE WILL SEE CONTINUED ISENTROPIC
UPGLIDE THROUGH THE MORNING AND AFTERNOON BEFORE DOWNGLIDE BEGINS
FROM WEST TO EAST LATE IN THE DAY AND EVENING.

ISENTROPIC ANALYSIS ALONG THE 285K SURFACE INDICATES MIXING RATIOS
OF 2 G/KG WILL CONTINUE TO PUMP INTO OUR SOUTH AND CENTRAL CWA WHERE
LIFT IS EXPECTED TO BE STRONGEST. THIS TRANSLATES TO POTENTIALLY
ANOTHER 4 INCHES OF SNOW IN THOSE AREAS...PUTTING TOTALS IN THE 3 TO
6 INCH RANGE IN MOST OF THE SOUTHERN HALF OF THE CWA. IN THE
NORTHERN HALF AND ESPECIALLY NORTHEAST NEBRASKA...SNOW WAS SLOW TO
BEGIN BUT HAS ENHANCED MARKEDLY OVER THE PAST SEVERAL HOURS. REPORTS
OF AN INCH OR TWO HAVE COME IN FROM NEAR THE SOUTH DAKOTA
BORDER...WITH LESSER AMOUNTS TO THE SOUTH. LIFT IN THAT AREA DOES
NOT LOOK AS STRONG AS TO THE SOUTH...BUT AMOUNTS COULD STILL
APPROACH 3 INCHES BEFORE ENDING. ALREADY HAVE A WINTER WEATHER
ADVISORY GOING FOR MOST OF THE CWA. SOUTHERN AREAS SHOULD EASILY
VERIFY THIS...BUT NORTHERN AREAS COULD STRUGGLE TO REACH THE LOWER
END OF CRITERIA. HOWEVER WILL MAINTAIN ADVISORY FOR ALL CURRENT
AREAS AS SNOW IS JUST GETTING GOING IN OUR NORTH AND EXPECT SOME
ENHANCEMENT DURING THE MORNING.

SNOW SHOULD BE TAPERING IN OUR WEST BY MID AFTERNOON...THEN EASTERN
SECTIONS THIS EVENING. CLEARING SKIES AND FRESH SNOW COVER WILL
ALLOW TEMPERATURES TO DROP BELOW ZERO IN MUCH OF THE CWA. NORTHWEST
WINDS OF 10 TO 15 MPH SHOULD DEVELOP LATER TONIGHT AND MONDAY
MORNING...AND WITH SUB ZERO TEMPERATURES...WIND CHILLS WILL APPROACH
20 BELOW FOR THE START OF THE SCHOOL/WORK WEEK. WILL GO AHEAD AND
ISSUE A WIND CHILL ADVISORY FOR A GOOD PART OF OUR NORTHERN CWA
FOR LATE TONIGHT AND MONDAY MORNING.

ANOTHER SHORTWAVE WILL DIVE INTO THE GREAT LAKES MONDAY
NIGHT...CAUSING SURFACE FLOW TO BECOME SOUTHWESTERLY HERE MONDAY
AFTERNOON. BUT COLD START AND SNOW WILL KEEP HIGHS ONLY IN THE
TEENS. THEN A CLIPPER SYSTEM/SHORTWAVE IS FORECAST THROUGH NORTHEAST
NEBRASKA INTO IOWA TUESDAY NIGHT. AGAIN THIS WILL BRING WEST TO
SOUTHWEST WINDS TO OUR AREA MONDAY NIGHT AND TUESDAY...KEEPING LOWS
ABOVE ZERO AND PUSHING HIGHS INTO THE 20S. MODELS HAVE BEEN
PERSISTENT IN DROPPING A STRIPE OF LIGHT SNOW WITH THIS SYSTEM
TUESDAY NIGHT INTO WEDNESDAY MORNING...SO WILL INSERT SMALL CHANCES
FOR THIS IN OUR NORTHEAST CWA. MUCH COLDER AIR BEHIND THE CLIPPER
WILL KEEP HIGHS IN THE TEENS ON WEDNESDAY. THEN A GRADUAL WARMING
TREND LOOKS ON TRACK FOR THURSDAY INTO SATURDAY AS UPPER FLOW
TRANSITIONS FROM A NORTHWEST TO ZONAL SETUP. HAVE HIGHS CLOSE TO 30
EACH DAY.

DERGAN

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR NEZ011-
     012-015>018-030>034-042>045-050>053-065>068-078-088>093.

     WIND CHILL ADVISORY FROM 3 AM TO NOON CST MONDAY FOR NEZ011-012-
     015>018-030>034-042>045.

IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ043-
     055-056-069-079-080-090-091.

     WIND CHILL ADVISORY FROM 3 AM TO NOON CST MONDAY FOR IAZ043-055.

&&

$$

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