FXUS63 KOAX 172108
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
308 PM CST MON JAN 17 2011
.SHORT TERM...TONIGHT THROUGH THURSDAY
WARMER TEMPS ARE UPON THE AREA TODAY AHEAD OF A FRONT...WITH SPOTTY
SHOWERS MOVING OUT OF THE AREA. SUBJECTIVE 12Z UPPER AIR ANALYSIS
INDICATES BROAD UPPER-LEVEL TROUGH EXTENDING FROM AROUND HUDSON BAY
THROUGH IA/MO TOWARD THE LOWER MS RIVER VALLEY...WITH CONTINUED
NWRLY FLOW ACROSS THE CNTRL US. STRONG UPPER-LEVEL JET EXTENDED
FROM THE PAC NW THROUGH WRN KS...WITH 160KT IN NW WA. 850MB DRY
SLOT LINGERED OVER THE CENTRAL PLAINS...WITH WARM NOSE EVIDENT AS 7C
TEMP AT KRAP AND 6C AT KOMA. SURFACE LOW AT 20Z WAS CENTERED IN W
CNTRL IA...WITH FRONT EXTENDING SWWD THROUGH KOMA TO KSLN. ON
EITHER SIDE OF THE FRONT...TEMPS HAD RISEN INTO THE 40S IN THE SRN
HALF OF NEB AND ABOVE FREEZING ACROSS THE CWA.
FORECAST ATTENTION IS PRIMARILY FOCUSED ON WEDNESDAY SNOW SYSTEM.
MUCH COLDER AIRMASS IN SD IS POISED TO PUSH INTO THE CWA THIS
EVENING/TONIGHT IN WAKE OF THE SFC LOW MOVING ACROSS THE AREA.
MEASURABLE PRECIP SEEMS TO BE DONE...BUT DID HOLD ONTO FZDZ MENTION
ON THE NOSE OF ARCTIC AIR MOVING IN THIS EVENING...WITH A FEW ECHOES
ON RADAR IN SD/WRN NEB. ALSO KEPT BLOWING SNOW MENTION IN THE
EVENING IN THE NRN CWA WHERE IT WAS AN ISSUE YESTERDAY. INCLUDED
LITTLE WARM-UP TUESDAY AS COLD AIR ADVECTION CONTINUES IN THE
MORNING...FOLLOWED BY A SURFACE RIDGE MOVING THROUGH IN THE
AFTERNOON/EVENING. NOTED THAT MODELS JUST GRAZE THE NRN CWA WITH
VERY LIGHT/DIMINISHING PRECIP LATE TUESDAY...BUT KEPT OUT OF THE
FORECAST GIVEN DRY AIR ASSOCIATED WITH THE RIDGING MOVING THROUGH.
IN WAKE OF THE SURFACE HIGH...AND ASSOCIATED WITH A DEEPENING UPPER
TROUGH MOVING ACROSS THE CENTRAL PLAINS...MODELS BREAK OUT PRECIP
AGGRESSIVELY ON WEDNESDAY IN CENTRAL NEB...SLIDING SEWD ACROSS SERN
NEB INTO SWRN IA THROUGH WEDNESDAY EVENING. WITH BAROCLINIC ZONE
NEAR THE KS-NEB BORDER...FGEN MAY HELP ENHANCE SNOW AMOUNTS...THOUGH
EVENT APPEARS TO BE PRIMARILY DRIVEN BY SYNOPTIC FORCING AS
SHORTWAVE MOVES THROUGH. 12Z NAM WAS MOST AGGRESSIVE WITH QPF...BUT
CONSENSUS AMONG GFS/ECMWF/GEM/SREF SOLUTIONS STILL POINTS TO A
SOLID 4-7 INCHES IN THE SRN CWA. AFTER MUCH CONSIDERATION...DID
OPT TO NOT ISSUE A WATCH WITH THIS PACKAGE...BUT IT WAS A VERY
CLOSE CALL...AS POTENTIAL FOR 6-INCH-AVERAGE SNOW AMOUNTS IS
CERTAINLY THERE IN THE SERN CWA BETWEEN 18Z WED-06Z THURS. TIME OF
DAY IS ALSO A CONSIDERATION...WITH AFTERNOON/EVENING SNOWFALL
LIKELY TO INTERFERE WITH COMMUTES AND END OF THE SCHOOL DAY. WILL
BEEF UP WORDING STRONGLY IN HWO AND ALLOW MID SHIFT TO CONSIDER
HEADLINE ISSUANCE. SNOW SHOULD END ON WEDNESDAY EVENING...WITH DRY
FORECAST ON THURSDAY AS SURFACE RIDGING AGAIN BUILDS INTO THE AREA.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
MODELS CONTINUE TO SHOW LONGWAVE MEAN TROUGH OVER THE MIDDLE OF THE
COUNTRY THROUGH THE WEEKEND...BUT RUN TO RUN AND MODEL TO MODEL
CONSISTENCY ON TIMING/TRACK/INTENSITY OF SHORTWAVES MOVING THROUGH
THAT TROUGH WAS POOR. OVERALL PATTERN SUGGESTS BELOW NORMAL
TEMPERATURES ON AVERAGE WITH AN OCCASIONAL SMALL CHANCE FOR
PRECIPITATION AS SHORTWAVES PASS BY.
PERIOD BEGINS RATHER COLD AS HIGH PRESSURE REMAINS NEAR THE MISSOURI
RIVER VALLEY THURSDAY NIGHT. FORECASTS HAVE SPED THE EASTWARD
RETREAT OF THE HIGH THE LAST COUPLE OF RUNS...MEANING LOWS MAY NOT
BE AS COLD AS PREVIOUS FORECASTS AS SOUTHERLY LOW LEVEL FLOW RETURNS
BEFORE SUNRISE. HOWEVER AM STILL EXPECTING SUB ZERO READINGS NEAR
AND EAST OF THE MISSOURI RIVER.
GFS AND ECMWF SHOW FIRST SHORTWAVE DIVING THROUGH THE NORTHERN
PLAINS ON FRIDAY...SPREADING LIGHT SNOW THROUGH MINNESOTA AND IOWA.
HAVE INSERTED SMALL POPS IN OUR NORTHEAST WITH THIS WAVE. A QUICK
WARM UP AHEAD OF THIS SYSTEM SHOULD PUSH HIGHS INTO THE 20S ON
FRIDAY WITH LOWS BACK INTO THE SINGLE DIGITS FRIDAY NIGHT BEHIND
SYSTEM. HIGHS SATURDAY MAY NOT REACH 20 AS HIGH PRESSURE SETTLES
OVER THE AREA WITH LIGHT WINDS KEEPING MIXING AT A MINIMUM. MID AND
HIGH LEVEL CLOUDS AHEAD OF NEXT SHORTWAVE WILL LIKELY DAMPEN
INSOLATION AS WELL.
THE NEXT SHORTWAVE IS TAKING A TRACK SOUTHWEST OF OUR AREA SATURDAY
NIGHT AND SUNDAY. SO WILL KEEP FORECAST DRY FOR NOW...BUT COULD SEE
A NORTHEAST TRACK ADJUSTMENT WITH LATER MODEL RUNS CAUSING POPS TO
BE INSERTED FOR SUNDAY. MODELS THEN DIVERGE EVEN MORE ON MONDAY WITH
GFS MOVING SUNDAY SHORTWAVE WELL SOUTH OF OUR AREA...WHILE ECMWF
ROTATES IT NORTHEAST THROUGH THE CWA. AGAIN WILL KEEP FORECAST DRY
FOR NOW UNTIL BETTER AGREEMENT IS SHOWN IN MODEL SOLUTIONS.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
THREAT OF FREEZING PRECIP HAS ENDED AS TEMPERATURES HAVE WARMED INTO
THE MID AND UPPER 30S AND RAIN PUSHED OFF INTO IOWA AND MISSOURI.
COLD FRONT JUST STARTING TO MOVE INTO NORTHEAST NEBRASKA AT 18Z AND
EXPECT FRONT TO PUSH ACROSS THE REMAINDER OF EASTERN NEBRASKA BY
00Z. MVFR CIGS LOCATED BEHIND THE FRONT UPSTREAM ACROSS SOUTH DAKOTA
WILL SPREAD INTO THE AREA BEHIND THE FRONT AND LINGER THROUGH THE
REMAINDER OF THE FORECAST PERIOD AT ALL THREE TAF SITES. GUSTY N TO
NW WINDS WILL ALSO ACCOMPANY THE COLD AIR AS IT SWEEPS INTO THE
AREA.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
MAYES/DERGAN/FOBERT