FXUS63 KOAX 050231 AAA
AFDOAX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
831 PM CST FRI FEB 4 2011
.UPDATE...
ADJUSTED A FEW LOWS TONIGHT AND MINOR CHANGES TO FOG/SKY GRIDS
BASED ON CURRENT TRENDS. ALSO MADE SMALL CHANGE TO SAT MORNING AS
WELL.
&&
.DISCUSSION...
LIGHT WINDS...SNOW COVER AND CLEAR SKIES HAS ALLOWED A FEW
SITES...MAINLY RIVER VALLEY ONES...TO DROP INTO UPPER TEENS AS OF
02Z. ALTHOUGH MILDER AIR WAS ATTEMPTING TO SPREAD SOUTHEASTWARD
COURTESY OF A MID CLOUD DECK...ADJUSTED LOWS SOME AREAS IN SERN
ZONES DOWNWARD. ALSO PUSHED BACK FOG MENTION UNTIL AFTER 06Z AS
TEMP/DEW POINT SPREADS MOST AREAS WERE STILL MODERATE. AFTER FIRST
MID CLOUD DECK PUSHES THROUGH SERN NEBRASKA EARLY TONIGHT...OTHER
DEEPER MOISTURE APPEARS IT WILL NOT ARRIVE UNTIL EITHER LATE SAT
MORNING OR UNTIL AFTERNOON SERN ZONES. THUS ALSO DROPPED MENTION
OF FREEZING RAIN THAT AREA FOR SATURDAY MORNING. NO OTHER CHANGES.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 310 PM CST FRI FEB 4 2011/
SHORT TERM...TONIGHT THRU MONDAY
LATEST WATER VAPOR IMAGERY SHOWS UPPER RIDGE ANCHORED OVER THE WEST
COAST WHILE A CLOSED LOW CONTINUES TO CIRCULATE OVER TEXAS. IN
BETWEEN THE TWO SYSTEMS...FAST NORTHWESTERLY FLOW CONTINUES TO
MOVE ACROSS SOUTHERN CANADA AND INTO THE NORTHWESTERN STATES. WEAK
SHORTWAVE ENERGY WITHIN THIS FAST NWRLY FLOW WL BEGIN TO AFFECT
THE CWA AS EARLY AS SATURDAY MORNING AS THE FIRST IN A SERIES OF PIECES
OF SHORTWAVE ENERGY EJECT OUT AHEAD OF MAIN TROF. CURRENTLY AT THE
SFC...TROF AXIS EXTENDS FROM EASTERN SOUTH DAKOTA INTO SOUTHWEST
KANSAS. SOUTHWESTERLY FLOW AHEAD OF THE TROF HAS ALLOWED DAYTIME
TEMPS TO CLIMB INTO THE 30S FOR THE MOST PART WITH LOWER TO MID
40S ACROSS CENTRAL NEBRASKA WITH LESS SNOW COVER. MID CLOUDS
CONTINUE TO MOVE IN BEHIND THE TROF AND A SECONDARY BANK OF LOWER
CIGS IN ASSOCIATION WITH THE SRN PLAINS SYSTEM CONTINUES TO PUSH
NORTH INTO EASTERN KANSAS. FORECAST MODELS CONTINUE TO INDICATE
THAT SOUTHERN CLOUD DECK SHOULD NOT AFFECT ANY OF THE FORECAST
AREA WHILE MID CLOUDS WILL CONTINUE TO SPREAD OVER THE REGION FROM
THE WEST. LIGHT WINDS ASSOCIATED WITH THE SFC TROF AND INCREASING
LLVL MOISTURE COULD CREATE PATCHY FOG OVERNIGHT.
AS LARGE SCALE LIFT INCREASES ACROSS NORTHEAST NEBRASKA AHEAD OF
THE FIRST OF MANY PIECES OF SHORTWAVE ENERGY...WL THROW IN SOME
PATCHY FREEZING DRIZZLE FOR THE EARLY MORNING HOURS. WE EXPECT
LIGHT PCPN THROUGHOUT MUCH OF SATURDAY AS LARGE SCALE FORCING
CONTINUES AHEAD OF ANOTHER WEAK PIECE OF SHORTWAVE ENERGY. PCPN
TYPE GETS A BIT MORE COMPLEX FROM 12-18Z SAT AS SOUNDINGS INDICATE
A WARM NOSE AROUND 2K FEET. WITH SFC TEMPS BELOW FREEZING DURING
THIS TIME PERIOD...WL GO WITH LIGHT FZRA BUT AM NOT ANTICIPATING
MUCH IN THE WAY OF ACCUMULATION BASED ON FAIRLY WEAK FORCING. SFC
TEMPS SHOULD GO ABOVE FREEZING FOR A SHORT TIME BETWEEN 18Z-00Z
WHICH WOULD TURN PCPN OVER TO -RA FOR A TIME BEFORE TRANSITIONING
OVER TO ALL SNOW BY EVENING. ACCUMULATIONS ARE EXPECTED TO REMAIN
VERY LIGHT WITH POTENTIALLY AN INCH OVER FAR NORTHEAST NEBRASKA BY
SUNDAY MORNING.
YET ANOTHER WEAK PIECE OF ENERGY MOVES THRU NWRLY FLOW TO CONTINUE
LIFT OVER THE CWA SUNDAY MORNING FOR CONTINUED SMALL CHANCES OF
SNOW INTO SUNDAY AFTERNOON. WL LEAVE MONDAY DRY AS WE STAY IN
BETWEEN SYSTEMS. ARCTIC AIR RUSHES IN QUICKLY BEHIND THIS
DROPPING TEMPS SIGNIFICANTLY AS 1040 MB HIGH BEGINS TO PUSH INTO
THE REGION.
LONG TERM...
MONDAY NIGHT THROUGH FRIDAY.
VERY COLD PERIOD MONDAY NIGHT THROUGH THURSDAY WITH TEMPERATURES 10
TO 20 DEGREES BELOW NORMAL...HOWEVER MODERATING BY NEXT FRIDAY. AT
THIS TIME...THE STORM SYSTEM TUESDAY NIGHT INTO WEDNESDAY NIGHT
LOOKS TO TAKE A TRACK MAINLY SOUTH OF THE FORECAST AREA.
THE FORECAST CHALLENGES IN THE EXTENDED FOCUS ON THE TEMPERATURE
DETAILS...HOW COLD WILL IT BE...HOW DEEP THE MID TROPOSPHERIC TROUGH
WILL BE OVER THE CENTRAL PLAINS...AND HOW QUICKLY IT WILL MOVE OUT.
IT STILL LOOKS COLD FROM MONDAY NIGHT THRU THURSDAY HOWEVER THERE
ARE DIFFERENCES IN HOW THE 00Z/12Z EUROPEAN CENTRE FOR MEDIUM RANGE
FORECAST (ECMWF)...12Z GLOBAL FORECAST SYSTEM MODEL (GFS)AND
ENSEMBLES HANDLE WHERE THE COLD AIR. NORTHWEST FLOW ALOFT CONTINUES
THROUGH THE PD WITH THE COLD AIR REMAINING IN PLACE...AND
MODERATION FRIDAY. THERE IS A BAND OF SNOW FROM THE ROCKIES INTO
NEBRASKA EARLY/MID WEEK. AT THIS TIME HAVE THE HIGHER PROBABILITY
OF PRECIPITATION (POP) TOWARD FAIRBURY AND BEATRICE AND THIS AREA
MAY TRY TO HOLD SOUTH OF THE FCST AREA. THURSDAY...THE THERMAL AXIS
SHIFTS EASTWARD WITH WESTERLY OR SOUTHWEST WINDS MODIFYING THE
ARCTIC AIRMASS AND TEMPERATURES WARMING UP 10 DEGREES...BUT STILL 10
DEGREES BELOW NORMAL.
AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
THERE IS SOME CHANCE OF IFR CEILINGS DEVELOPING TONIGHT...MAINLY AT
KOMA...BUT FELT THE CHANCE WAS LOW ENOUGH TO LEAVE OUT FOR NOW. MVFR
CONDITIONS ARE POSSIBLE DUE TO PATCHY FOG. WESTERLY WIND COMPONENT
IS EXPECTED TO LIMIT FOG AT THIS TIME. MVFR CEILINGS COULD DEVELOP
AFTER 12Z SATURDAY...BUT ARE MORE LIKELY AFTER 18Z. ALSO FELT THAT
PRECIPITATION CHANCES WERE LOW ENOUGH TO LEAVE OUT PRIOR TO 18Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
KERN/ZAPOTOCNY/MILLER