000
FXUS63 KOAX 052124
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
324 PM CST THU DEC 5 2013

.SHORT TERM...TONIGHT THROUGH SUNDAY

MAIN FORECAST CONCERNS THIS PERIOD ARE WITH BITTERLY COLD
TEMPERATURES AND SNOW OVER THE WEEKEND. ARCTIC HIGH PRESSURE THIS
AFTERNOON EXTENDED FROM ERN MT INTO CNTRL NEB...AND THIS PATTERN
WILL REMAIN IN PLACE OVER THE NEXT 24 HOURS. THIS WILL KEEP THE
BOUNDARY LAYER MIXING GOING OVERNIGHT AND A NORTHWEST WINDS AOA 8
KT IN MOST PLACES. THIS IN COMBINATION WITH LOWS FALLING INTO THE
5 TO 10 BELOW ZERO RANGE IN THE NORTH WILL CREATE WIND CHILL
VALUES LESS THAN -20 F. THUS WE WILL ISSUE ANOTHER WIND CHILL
ADVRY FOR PARTS OF THE AREA. OTHERWISE IN THE CNTRL AND SOUTH
WE HAVE INCREASED OVERNIGHT LOWS A TOUCH MOST AREAS AS SOUTHERN
STREAM SYSTEM MOVES ACROSS THE SOUTHERN PLAINS WE EXPECT A DECENT
AMOUNT OF HIGH LEVEL CLOUDS WILL STREAM ACROSS THIS AREA. THE COLD
TEMPERATURES WILL CONTINUE FOR FRI THROUGH SAT WITH THE ARCTIC
HIGH PRESSURE SLOWLY CROSSING THE MID AND UPPER MO RIVER VALLEY
INTO THE UPPER MS RIVER VALLEY.

WARM AIR ADVECTION WILL GET GOING ON SAT THOUGH AS ANOTHER
SHORTWAVE TROUGH DIGS THROUGH THE GREAT BASIN. WE SHOULD SEE
INCREASING CLOUDS THROUGH THE DAY...BUT ANY SNOWFALL WILL LIKELY
HOLD OFF UNTIL SAT NIGHT. THE MODELS ARE IN FAIR AGREEMENT IN THE
UPCOMING SNOW EVENT THOUGH THE 12Z NAM APPEARS A BIT HIGH ON QPF
AND TO FAST IN ENDING THE SNOWFALL SUN AFTN. BROAD BUT PERSISTENT
ISENTROPIC LIFT ON SAT NIGHT WILL LEAD TO SATURATION AND THE
STARTING OF -SN OVER NORTHEAST NEBRASKA INITIALLY...BUT THIS WILL
EXPAND TO ALONG AND EAST OF THE MO RIVER BY SUN MORNING. SNOWFALL
WILL THEN CONTINUE THROUGH THE DAY ON SUNDAY...ALTHOUGH THE
INTENSITY MAY VARY AT TIMES DEPENDING ON TIMING ON INDIVIDUAL
SHORTWAVE TROUGHS. ISENTROPIC ANALYSIS INDICATES AROUND 2 G/KG OF
SPECIFIC HUMIDITY STEADILY FEEDING INTO THE AREA DURING THE
PERIOD...AND A VERY DEEP THERMAL PROFILE WITHIN THE DENDRITIC
GROWTH ZONE /~ >200 MB IN DEPTH/ PER POINT FORECAST SOUNDING
YIELDING VERY EFFECTIVE SNOWFALL. SNOW RATIOS ARE A BIT DIFFICULT
TO DISCERN AT THIS RANGE...BUT NEARLY 16-19:1 SEEMS REASONABLE.
THIS WILL LIKELY LEAD TO A BROAD AREA OF ADVISORY TYPE SNOWFALL
FOR THE SECOND HALF OF THE WEEKEND. WE HAVE INCREASED POPS TO CAT
FOR PARTS OF THE AREA FOR SAT NIGHT AND SUN.

BOUSTEAD

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY.

AT THE BEGINNING OF THE EXTENDED...A LARGE...BROAD MID LEVEL TROF
EXTENDS FROM MANITOBA SOUTHWARD TOWARD NEVADA...NEW MEXICO...AND
OKLAHOMA.  ACCUMULATING SNOW WILL BE ONGOING WITH THE BRUNT OF THE
SNOW OVER IOWA AND THE LINGERING WESTERN EDGE INTO THE LOCAL AREA.
WILL MENTION LIKELY POPS SUNDAY EVENING THEN TAPER OFF FOR MUCH OF
THE AREA BY 06Z.

A REINFORCING SHOT OF COLD AIR WILL FOLLOW IN BEHIND THE STORM
SYSTEM WITH THE AXIS OF THE COLDEST AIR PLUNGING INTO DAKOTAS AND
MINNESOTA MONDAY.  INCREASED THE NORTHWEST WINDS MONDAY TO THE 15 TO
30 MPH RANGE.  WITH THE SNOW FROM THE WEEKEND...THIS COULD CAUSE
SOME BLOWING AND DRIFTING OF SNOW. A COUPLE OF SHORTWAVE TROFS ARE
PROGGED TO MOVE THROUGH THE BACK SIDE OF THE MID LEVEL TROF...ONE
MONDAY NIGHT AND ANOTHER TUESDAY NIGHT INTO WEDNESDAY.  THERE COULD
BE SOME FLURRIES MONDAY NIGHT AND MAY NEED TO ADD A CHANCE FOR LIGHT
SNOW TUESDAY NIGHT IF THERE IS BETTER MODEL CONSISTENCY. THERE IS
SOME MODERATION AHEAD OF EACH OF THESE TROFS...HOWEVER THEY ARE
SHORT-LIVED WITH COLD AIR ON THE BACK-SIDE.  TEMPERATURES SHOULD BE
COLDEST MONDAY WITH BELOW NORMAL HIGHS IN THE TEENS. WARMER
TEMPERATURES IN THE 20S AND A FEW 30S ARE FORECAST TUESDAY THROUGH
THURSDAY.

ZAPOTOCNY

&&

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

VFR CONDITIONS WILL PREVAIL THROUGH THE FCST PERIOD. NORTHWEST
WINDS GUSTING AROUND 20KT WILL SUBSIDE BY LATE THIS AFTN.

DEE

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST FRIDAY FOR
     NEZ011-012-015>018-030>032.

IA...NONE.

&&

$$