FXUS63 KOAX 082119
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
319 PM CST WED DEC 8 2010
.SHORT TERM...TONIGHT THROUGH SATURDAY. MAIN FORECAST CONCERN IS
THE IMPENDING WINTER WEATHER SYSTEM THAT WILL AFFECT THE AREA
FRIDAY NIGHT THROUGH SATURDAY NIGHT WITH A VARIETY OF WINTRY
WEATHER EXPECTED.
IN THE MEANTIME...A WEAK FRONT THAT HAD MOVED INTO NORTHEAST
NEBRASKA EARLY THIS MORNING HAS MOVED VERY LITTLE...AND WILL
ESSENTIALLY DISSIPATE THROUGH THE EVENING. TO THE NORTH OF THE
FRONT ACROSS NORTHEAST NEBRASKA...A DECK OF VERY LOW STRATUS HAD
DEVELOPED...AND THIS MAY BE HARD TO BREAK AS WE HEAD TOWARD DARK.
MEANWHILE...AN EXPANSIVE CIRRUS SHIELD WAS ALREADY STARTING TO
INVADE FROM THE WEST...IN RESPONSE TO AN UPPER LEVEL WAVE THAT
WILL MOVE THROUGH THE NORTHERN PLAINS AND INTO THE UPPER
MISSISSIPPI RIVER VALLEY TONIGHT. OUR CWFA SHOULD REMAIN DRY
OVERNIGHT...WITH SNOW WELL TO THE NORTH ACROSS THE DAKOTAS AND
MINNESOTA. THIS WEATHER SYSTEM WILL DRAG A WARM FRONT ACROSS THE
AREA TOMORROW...RESULTING IN SOUTHERLY WINDS AT DAYBREAK...BUT
BECOMING WEST NORTHWEST THROUGH THE AFTERNOON...BUT WITH
TEMPERATURES WARMING INTO THE MID 40S TO LOWER 50S. WEAK WESTERLY
FLOW THURSDAY NIGHT WITH TEMPS SLIGHTLY ABOVE NORMAL IN THE 20S.
AS THE NEXT WAVE CROSSES THE ROCKIES ON FRIDAY...CYCLOGENESIS
ALONG THE LEE OF THE ROCKIES BEGINS...WITH A WARM FRONT DEVELOPING
EASTWARD ALONG OR JUST NORTH OF I80. BOTH THE GFS/ECMWF TRY TO
DEVELOP SOME SPOTTY PRECIP FRIDAY AFTERNOON ALONG THE FRONTAL
BOUNDARY....BUT OTHER MODEL SUITES ARE DRY FRIDAY AFTERNOON...AND
FEEL THIS IS THE TREND TO FOLLOW FOR THE MOMENT. HOWEVER...THAT
QUICKLY CHANGES FRIDAY NIGHT. STRONG ISENTROPIC LIFT AHEAD OF THE
SURFACE LOW SHOULD ALLOW A FEW SHOWERS TO DEVELOP FRIDAY EVENING
ACROSS EAST CENTRAL NEBRASKA AND WESTERN IOWA. FURTHER NORTH NEAR
THE THE SOUTH DAKOTA BORDER...WITH SIGNIFICANTLY LESS OR EVEN NIL
ISENTROPIC LIFT...NOT MUCH MAY OCCUR FRIDAY EVENING. AS THE UPPER
TROUGH MOVES EASTWARD THOUGH ALONG THE NE/SD BORDER...AND COLDER
ARCTIC AIR GETS PULLED RAPIDLY SOUTHWARD AS THE SURFACE LOW MOVES
TO NORTHWEST MISSOURI...PRECIP TYPE ISSUES BECOME A PROBLEM. THERE
LIKELY WILL BE A RAPID CHANGEOVER TO SNOW IN OUR NORTHERN
CWFA...BUT THERE WILL ALSO LIKELY BE A TRANSITION ZONE OF MESSY
WINTRY PRECIPITATION IN BETWEEN WITH FREEZING RAIN OR SLEET
POSSIBLE...BUT REMAINING ALL RAIN NEAR THE TRI STATE NE/KS/MO
BORDER REGIONS.
BY DAYBREAK SATURDAY...WINDS ON THE BACKSIDE OF THE LOW SHOULD HAVE
SUBSTANTIALLY INCREASED INTO THE 25 TO 35 MPH RANGE. THERE COULD
BE A VERY BRIEF PERIOD OF RAIN ACROSS EXTREME SOUTHEAST NEBRASKA
AND SOUTHWEST IOWA SATURDAY MORNING BEFORE QUICKLY CHANGING TO
SNOW. THIS IS ALSO WHERE THE FORECAST GETS A LITTLE TRICKY. THE
NAM/GFS FOCUS THE BULK OF THE PRECIP ACROSS IOWA IN A NORTHWEST TO
SOUTHEAST BAND...AND IN FACT GIVE LITTLE IF ANY SNOW AT ALL TO
SOUTHEAST NEBRASKA. MEANWHILE...THE SREF/ECMWF/GEM REMAIN TIGHTLY
CLUSTERED IN SHOWING MORE OF A SNOW THREAT IN A SOUTHWEST TO
NORTHEAST BAND WHICH SEEMS MORE REASONABLE. NOW...HAVING SAID
THAT...STILL PLAN TO CARRY 50/60 PERCENT POPS SATURDAY...AND ALSO
HAVE ADDED IN A MENTION OF BLOWING SNOW AS WELL. SNOWFALL AMOUNTS
STILL DONT LOOK OVERLY IMPRESSIVE...HOWEVER WHEN COMBINED WITH A
NORTHWEST WIND AT 25 TO 35 MPH...THIS COULD RESULT IN SOME TRAVEL
DIFFICULTIES WITH VISIBILITY ISSUES.
STILL NOT SIGNIFICANT ENOUGH YET FOR ANY TYPE OF WINTER STORM WATCH
BUT WOULD NOT BE SURPRISED TO SEE THIS TRANSITION INTO AN ADVISORY
TYPE OF EVENT AS WE GET CLOSER...MAINLY DUE TO BLOWING SNOW AND/OR
TRAVEL/VISIBILITY ISSUES. WILL CONTINUE TO HIGHLIGHT THE IMPACT
THOUGH...ESPECIALLY WITH A COUPLE OF MILD DAYS THROUGH THE REMAINDER
OF THE WEEK BEFORE THE TRANSITION BACK TO WINTER OCCURS.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. OVERALL QUIET
PERIOD EXPECTED AS THE WEEKEND SYSTEM CONTINUES TO MOVE
EAST...LEAVING BEHIND NORTHWESTERLY FLOW EARLY IN THE
WEEK...TRANSITIONING TO A WEAK OR FLATTENING RIDGE THROUGH MID
WEEK. THERE COULD BE A FEW FLURRIES ACROSS THE NORTHERN PLAINS
MONDAY NIGHT THROUGH TUESDAY...AND HOW FAR SOUTH THESE EXTEND DOWN
THE RIDGE REMAIN THE QUESTION WITH GFS EXTENDING THEM AS FAR
SOUTH THE MID MISSISSIPPI RIVER VALLEY. FOR NOW...FOLLOWED MORE
OF THE ECMWF PATTERN AND KEPT THE LOCAL CWFA DRY ATTM...WITH A
GRADUAL WARMING TREND BACK TO NEAR NORMAL BY MID WEEK. SUNDAY
NIGHT/MONDAY COULD BE VERY CHILLY THOUGH AS ARCTIC HIGH PRESSURE
REMAINS OVERHEAD...WITH A VERY LIGHT SNOW COVER POSSIBLY FROM THE
WEEKEND SYSTEM.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
SURFACE INVERTED TROF THAT WILL MOVE SLOWLY THROUGH THE REGION WILL
IMPACT TAF SITES BY KEEPING WINDS FAIRLY LIGHT AND HUMIDITY
RELATIVELY HIGH. STRATUS DECK THAT IS OVER NORTHEAST NEBRASKA AND
INTO NORTHERN IOWA WILL LINGER THROUGH TONIGHT AND MAY EXPAND
SLOWLY. IN ADDITION...LIGHT FOG FORMATION IS AGAIN EXPECTED BEFORE
SUNRISE.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$