FXUS63 KOAX 162131
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
331 PM CST SUN JAN 16 2011
.SHORT TERM...TONIGHT THROUGH WEDNESDAY.
SEVERAL FORECAST CHALLENGES THROUGH THE SHORT TERM AND WILL FOCUS
ON LIGHT PRECIPITATION TONIGHT AND MONDAY AND TEMPERATURES/PRECIP
TYPE.
SFC HIGH PRES AT 20Z WAS CENTERED OVER WI/IL WITH SOUTH FLOW ACRS
THE CWA AND TEMPERATURES IN THE TEENS AND 20S. MUCH WARMER AIR WAS
NOTED OUT IN WESTERN NEBRASKA WITH TEMPERATURES IN THE 40S AND
50S. SKIES WERE MOSTLY CLOUDY...HOWEVER THERE WERE SOME BREAKS IN
THE SW CWA. SFC LOW PRES WAS OVER MT. A LOOK AT THE WATER VAPOR
IMAGERY WITH UPR LEVEL FEATURES OVERLAID REVEALS A STRONG
120-140KT JET FM MT TO OFF THE PACIFIC NORTHWEST COAST AND THERE
WAS SOME LIGHTNING ASSOCIATED WITH THIS FEATURE AND 60M HT FALLS
WERE NOTED ON THE 12Z UA MAPS WITH THE SHORTWAVE TROF AND THE
REGION WAS UNDER NW FLOW ALOFT.
TONIGHT AS THE SHORTWAVE TROF MOVES INTO THE PLAINS...SFC LOW PRES
ALSO MOVES EASTWARD...WITH WARMING TEMPERATURES SPREADING
EASTWARD. UVV INCREASES ALONG WITH WAA OVERNIGHT AND SATURATION
OCCURS ON THE 285/295K SFCS THIS EVENING IN THE WRN CWA AND
SPREADING EASTWARD OVERNIGHT AND MONDAY MORNING. MID LEVEL
FRONTOGENSIS IS STRONG DURING THE PD FROM 06Z-12Z...HOWEVER
QUICKLY DIMISHES. THE UPR LEVEL JET AND THE LEFT EXIT REGION OF
THE JET WILL ALSO PROVIDE SOME UPR LEVEL SUPPORT. CONCERNS
OVERNIGHT WILL BE FREEZING DRIZZLE AND FREEZING RAIN AS FORECAST
SOUNDINGS SHOW A WARM LAYER OF +5/6 AT H85 ON THE NAM AND PLUS 1
TO 2 ON THE GFS AT 06Z...THEN REVERSE WITH THE NAM 1 TO 2 BY 12Z
AND THE GFS PLUS 6 AT H85. THERE APPEARS TO BE HIGH RH AND VERY
COLD AIR -10 TO -20 ALOFT...AND RUC IS IN- BETWEEN...THUS FORECAST
SOUNDINGS A MIX OF SLEET/FREEZING RAIN/FREEZING DRIZZLE IS
EXPECTED BEFORE SFC TEMPERATURES WARM ABOVE FREEZING. RISK PD
ESPECIALLY 03Z TO 15Z. AN ADVISORY MAY BE NEEDED DUE TO THE
FREEZING RAIN/FREEZING DRIZZLE AND THE TIME OF DAY WITH IS BEING
DURING THE MORNING RUSH. AT THIS TIME HAVE QPF AMOUNTS OF 0.1 OR
LESS...HOWEVER EVEN THESE SMALL AMOUNTS CAN CAUSE PROBLEMS ON
UNTREATED SURFACE. HAVE TEMPERATURES WARMING OVERNIGHT WITH
INCREASING SOUTH WINDS. EXPECT EVENING LOWS FOR THE PERIOD AND
WARMING INTO THE 30S MONDAY. DRIZZLE OR FREEZING DRIZZLE WILL BE
POSSIBLE IN THE AFTERNOON...HOWEVER COLDER AIR WILL PUSH IN
OVERNIGHT AND COULD SEE SOME FLURRIES OR LIGHT SNOW ON THE
BACKSIDE WITH LITTLE OR NO ACCUMULATION.
ANOTHER VERY WEAK SHORTWAVE TROF WILL BRING CLOUDS BACK IN FOR
MONDAY NIGHT AND WINDS ARE NOT EXPECTED TO DIE DOWN UNTIL WED
AM...THUS TUESDAY MORNING LOWS SHOULD HOLD IN THE SINGLE DIGITS
AND TEENS SOUTH. HIGHS TUESDAY SHOULD REMAIN COLD WITH SINGLE
DIGITS NORTH AND TEENS SOUTH. THE SFC HIGH SETTLES IN TUESDAY
NIGHT AND HAVE LOWS IN THE SINGLE DIGITS ABOVE AND BELOW
ZERO...HOWEVER CLOUDS WILL ALREADY BEGIN MOVING INTO THE WEST WED
MORNING WITH THE NEXT STORM SYSTEM.
THE SFC LOW PRES SYSTEM FOR WED ORGANIZES OVER SOUTHEAST COLORADO
AND THE TX PANHANDLE. THERE IS A GOOD AMOUNT OF LIFT INTO NEB AND
SOME QUESTION AS TO THERE THE BEST FORCING WILL ORGANIZE. AT THIS
TIME LOOKS LIKE AT SHOT AT SOME ACCUMULATING SNOW AND WILL
MAINTAIN CHC TO LIKELY POPS WED.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY.
AGAIN TODAY MOST MEDIUM RANGE MODELS AND THEIR ENSEMBLE MEMBERS
AGREE ON MAINTAINING A BROAD TROUGH ACROSS THE MIDDLE OF THE
COUNTRY...BUT MODELS DIFFER ON TIMING/PLACEMENT OF SHORTWAVES
ROLLING THROUGH THE MEAN FLOW AND THE AFFECT ON SENSIBLE WEATHER
HERE. HOWEVER MOST MODELS/ENSEMBLES AGREE ON ONE SHORTWAVE/SYSTEM
EXITING OUR AREA WEDNESDAY NIGHT...THEN ANOTHER ONE MOVING THROUGH
FRIDAY OR SATURDAY...AND YET ANOTHER APPROACHING THE AREA AT THE END
OF THE PERIOD. BETWEEN EACH SYSTEM A BLAST OF COLD AIR THEN A QUICK
TURN AROUND TO WARM ADVECTION PRESENTS A TOUGH TEMPERATURE FORECAST.
12Z RUNS OF THE GFS AND ECMWF WERE FAIRLY CONSISTENT TODAY...AND HAD
SUPPORT OF A MAJORITY OF GFS ENSEMBLE MEMBERS. THUS A BLEND OF THOSE
MODELS WAS FOLLOWED. SYSTEM EXITING ON WEDNESDAY NIGHT APPEARS A BIT
SLOWER AND FARTHER NORTH THAN PREVIOUS RUNS...SO HAVE KEPT A CHANCE
FOR SNOW GOING THEN. CLEARING SKIES AND COLD ADVECTION THURSDAY WILL
KEEP TEMPERATURES COOL...WITH THURSDAY NIGHT A TRICKY FORECAST.
SURFACE RIDGE OVER THE MISSOURI RIVER VALLEY AT 00Z FRIDAY WILL
QUICKLY SLIDE EAST BRINGING SOUTHERLY FLOW BACK TO OUR AREA. EXPECT
COLD TEMPERATURES THURSDAY NIGHT...BUT SOUTHERLY FLOW SUGGESTS
WARMER THAN PREVIOUS FORECAST. THUS WILL RAISE MINS A FEW CATEGORIES
THEN.
FRIDAY LOOKS WARMER...OR MAYBE NOT AS COLD...THAN PREVIOUS FORECAST
AS WELL WITH SOUTH OR SOUTHWEST FLOW AHEAD OF APPROACHING
SYSTEM...BUT HIGHS STILL ONLY IN THE 20S. COLD FRONT SWEEPS THROUGH
FRIDAY NIGHT...AND WILL LIKELY TOUCH OFF SOME LIGHT SNOW. WILL
INTRODUCE SMALL POPS THEN...WHICH WILL LINGER INTO SATURDAY. HIGH
PRESSURE SETTLING INTO THE REGION SATURDAY SHOULD HOLD TEMPS IN THE
TEENS...BUT MIXING BEHIND FRONT MAY BUMP HIGHS INTO THE LOWER 20S.
LOWS SATURDAY NIGHT SHOULD FALL TO OR BELOW ZERO WITH LIGHT WINDS
UNDER HIGH PRESSURE REGIME. THEN ANOTHER QUICK SWITCH TO SOUTHERLY
FLOW SUNDAY SUGGESTS HIGHS BACK IN THE 20S.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
MVFR CONDITIONS EXPECTED TO DETERIORATE AFTER ABOUT 03Z AS MID LEVEL
WAVE MOVES INTO THE REGION WITH INCREASED VERTICAL MOTION SQUEEZING
OUT SOME LIGHT FREEZING RAIN OR SLEET IN WARM ADVECTION ZONE AHEAD
OF NORTHERN PLAINS CLIPPER. IFR CIGS SHOULD DEVELOP DURING THIS TIME
AND EXTEND THROUGH THE REMAINDER OF THE FORECAST PERIOD.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY/DERGAN/DURHAM/FOBERT