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000
FXUS63 KOAX 181734
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1134 AM CST WED DEC 18 2013


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

VFR CONDITIONS ARE EXPECTED THROUGH AT LEAST 06-09Z. A COOL FRONT
WILL TURN WINDS FROM SOUTHWEST THIS AFTERNOON TO NORTHWEST
OVERNIGHT. IN ADDITION...INCREASING LOW LEVEL RELATIVE HUMIDITY
WILL BRING A STRATUS DECK OVER THE TAF SITES FROM NORTH TO SOUTH.
SOME FOG MAY BE POSSIBLE...ESPECIALLY AT KLNK AND KOMA TOWARD 12Z
BEFORE NORTHEASTERLY SFC WINDS BEGIN TO INCREASE. THIS WIND
INCREASE WILL BE THE SECONDARY SURGE OF COLD AIR TO SWEEP THROUGH
THE REGION WHILE LOW LEVEL MOISTURE CONTINUES TO INCREASE. THERE
IS A SMALL RISK OF FREEZING DRIZZLE FROM 12-18Z AND
BEYOND...HOWEVER WILL BE LEAVING THIS MENTION OUT OF TAFS AT THIS
POINT DUE TO SOME FORECASTER UNCERTAINTY.

KERN

&&

.PREV DISCUSSION... /ISSUED 306 AM CST WED DEC 18 2013/

DISCUSSION...
ONE MORE DAY OF MILD WEATHER...BEFORE COLD AIR INTRUDES AGAIN.
SUBJECTIVE 00Z UPPER AIR ANALYSIS INDICATES AN UPPER-LEVEL TROUGH
OVER THE EASTERN GREAT LAKES...WITH WEAK RIDGING OVER THE GREAT
BASIN.  IN BETWEEN...500MB HEIGHTS WERE RISING AS MUCH AS 160M/12HR
OVER THE CENTRAL US...AND HEIGHTS WERE FALLING AS MUCH AS 100M/12HR
IN THE PACIFIC NORTHWEST.  NORTHWESTERLY UPPER-LEVEL JET STREAK WAS
NOTED IN MN BEHIND THE GREAT LAKES TROUGH.  AT 850MB...TIGHT
TEMPERATURE GRADIENT WAS NOTED ACROSS THE CENTRAL US...WITH WARM
TEMPERATURES EXTENDING FROM THE HIGH PLAINS INTO MT WEST OF A
RIDGE AXIS...AND SUB-0C TEMPERATURES FROM THE DAKOTAS AND EASTERN
NEB TO THE GREAT LAKES. LITTLE 850MB MOISTURE WAS NOTED...WITH
TEMPERATURE/DEWPOINT SPREADS OF 5C OR LESS ONLY IN THE EXTREME
NORTHWESTERN CONUS AND OVER THE GREAT LAKES TO MID-ATLANTIC.
SURFACE HIGH AT 08Z HAD SLID SOUTHEAST TOWARD THE LOWER MS RIVER
VALLEY...WITH SURFACE TROUGHING FROM WESTERN SD THROUGH THE HIGH
PLAINS TO SOUTHEAST CO/NORTHEAST NM...AND WITH A TIGHT PRESSURE
GRADIENT BETWEEN ALLOWING WINDS TO REMAIN AT 10 TO 15 MPH
OVERNIGHT.

MAIN FORECAST CONCERN IS POTENTIAL FOR DRIZZLE OR PRECIPITATION ON
THURSDAY/THURSDAY NIGHT...AND ANOTHER CHANCE OF PRECIPITATION ON
SATURDAY/SATURDAY NIGHT.  ONE MORE MILD DAY IS EXPECTED ACROSS THE
CWA...WITH BETTER MIXING AND MID-LEVEL WARM AIR ADVECTION TODAY
ALLOWING TEMPERATURES TO LIKELY REACH THE 50S IN MANY
LOCATIONS...ESPECIALLY ALONG AND WEST OF THE MO RIVER. GIVEN DRY
LOWER LEVELS EXTENDING ACROSS MUCH OF THE CENTRAL US...HAVE
SLOWED ONSET OF CLOUDS AS WELL AS EITHER DRIZZLE OR PRECIP ON
WEDNESDAY NIGHT/THURSDAY. SURFACE LOW WILL CLOSE OFF OVER
SOUTHEAST CO ON THURSDAY...THEN SLIDE TO THE EAST AS AN UPPER-
LEVEL SHORTWAVE EJECTS ACROSS THE PLAINS. IN WAKE OF THAT
LOW...COLD AIR WILL INTRUDE INTO THE CENTRAL PLAINS...WITH
TEMPERATURES STEADY TO FALLING IN THE NORTHWEST CWA...AND WITH
EARLY MAX TEMPS ELSEWHERE. MODEL SOUNDINGS AND CROSS-SECTIONS
INDICATE A DEEPENING MOIST LAYER NEAR THE SURFACE...WITH A STOUT
DRY MID-LEVEL AIRMASS...AND WITH LIFT JUST ABOVE THE MOIST LAYER
AT AROUND 850-700MB. SITUATION LOOKS FAVORABLE FOR LIGHT FREEZING
DRIZZLE ONCE LOWER LEVELS SATURATE DEEPLY ENOUGH...AND HAVE
MENTIONED FREEZING DRIZZLE FROM LATER THURSDAY AFTERNOON THROUGH
AROUND MIDNIGHT THURSDAY NIGHT. BROAD AREA OF LIGHT SNOW IN NORTH
CENTRAL NEB TO SOUTHEAST SD MAY JUST CLIP THE NORTHERNMOST
CWA...BUT ONLY ENOUGH TO PRODUCE A DUSTING OF SNOW ACCUMULATION.
ALSO...ALONG THE FRONT NEAR OR JUST SOUTH OF THE CWA...MEASURABLE
PRECIPITATION MAY DEVELOP...AND HAVE INCLUDED A MEASURABLE MENTION
THERE ON THURSDAY EVENING...WITH SOME KIND OF SLEET OR LIGHT
FREEZING RAIN THE MOST LIKELY PRECIPITATION TYPE. ALL IN
ALL...AMOUNTS OF ANY POTENTIAL PRECIP LOOK LIGHT...BUT ANY
FREEZING DRIZZLE CAN MAKE ROADS SLICK...AND WILL CONTINUE TO
HIGHLIGHT IN HWO.

SYSTEM WILL MOVE TO THE EAST BY FRIDAY MORNING...WITH DRY AND COOLER
WEATHER ON FRIDAY/FRIDAY NIGHT.  MEANWHILE...UPPER-LEVEL LOW IS
PROGGED TO DEVELOP IN THE BAJA AREA...WITH SOUTHWESTERLY FLOW ACROSS
THE CENTRAL US.  NORTHERN STREAM UPPER-LEVEL SHORTWAVE IS PROGGED TO
SLIDE ACROSS THE DAKOTAS/MN ON SATURDAY...AND STRONG UPPER-LEVEL
LOW...OPENING TO A DEEP TROUGH...WILL MOVE ACROSS THE SOUTHERN
PLAINS TO MID MS RIVER VALLEY ON SATURDAY/SUNDAY.  SURFACE BOUNDARY
WILL HAVE STALLED OVER KS/MO ON SATURDAY...AND PRECIPITATION IS
EXPECTED TO DEVELOP ALONG AND BEHIND THIS FRONT AS THE TROUGH MOVES
ACROSS.  BELIEVE NORTHERN STREAM INFLUENCE WILL STAY WELL NORTH OF
THE CWA...BUT SOUTHERN STREAM TROUGH MAY PUSH SOME PRECIP INTO THE
SOUTHEASTERN CWA ON SATURDAY/SATURDAY NIGHT.  PRECIPITATION TYPE
COULD AGAIN BE MIXED ON SATURDAY...DEPENDING ON THE LOCATION OF THE
850MB FRONT RELATIVE TO THE COLD SURFACE AIR...BUT IT SHOULD BE ALL
SNOW BY SATURDAY NIGHT AS REINFORCING PUSH OF COLD AIR OVERTAKES THE
CWA IN WAKE OF THE TROUGH.  WITH DRY AIR FEEDING IN FROM THE
NORTH...DO EXPECT A SHARP CUTOFF TO THE PRECIPITATION ON THE NORTH
SIDE...AND HAVE LIMITED NORTHWARD EXTENT OF POPS FOR THE EVENT.

BEHIND THE WEEKEND SYSTEM...TEMPERATURES AGAIN MODERATE TO NEAR
NORMAL AS WARM AIR ADVECTION COMMENCES.  LACKING A SNOWPACK ACROSS
THE AREA /WITH THE POTENTIAL EXCEPTION OF THE SOUTHERN CWA/...EXPECT
TEMPS TO BE MORE LIKELY TO LEAN TOWARD THE WARMER SIDE OF GUIDANCE.
AT THIS POINT...IT LOOKS LIKE MOST OF THE CWA WILL BE LIKELY TO
SEE A BROWN CHRISTMAS RATHER THAN A WHITE ONE.

MAYES

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$