FXUS63 KOAX 222055
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
255 PM CST TUE FEB 22 2011
.SHORT TERM...TONIGHT THROUGH FRIDAY.
THE MAIN FORECAST CONCERNS ARE PCPN CHANCES...ESPECIALLY THURSDAY
AND FRIDAY. GENERALLY USED A BLEND OF 12Z MODEL SOLUTIONS THROUGH
THURSDAY WITH HEAVIEST WEIGHT GIVEN TO ECMWF WITH GFS SECOND. THE
NAM WAS NOT GIVEN MUCH WEIGHT FOR THURSDAY BUT SURPRISINGLY IT DID
NOT SEEM TOO BAD FOR FRIDAY.
500 MB PATTERN OVER NORTH AMERICA EARLY THIS AFTERNOON FEATURED
FAIRLY STRONG NORTHWEST FLOW JUST OFF THE COAST OF BRITISH
COLUMBIA...WITH 300 MB WINDS IN EXCESS OF 120 KTS. THE FLOW WAS
SPLIT FARTHER DOWNSTREAM WITH A CLOSED LOW OFF THE COAST OF BAJA
CALIFORNIA NEAR 30N 125W AND A TROUGH EXTENDING FROM SASKATCHEWAN
INTO THE NORTHERN PARTS OF NEVADA AND UTAH. 12 HOUR HEIGHT FALLS
WERE AS HIGH AS 120 METERS AT SPOKANE THIS MORNING. THE SHORTWAVE
TROUGH PASSING TO OUR NORTH WILL ALLOW A LOW PRESSURE SYSTEM TO
MOVE ACROSS THE NORTHERN AND CENTRAL PLAINS TONIGHT AND WEDNESDAY.
FAIRLY MILD AIR SHOULD BE PULLED NORTH INTO OUR AREA...WITH HIGHS
EXPECTED TO REACH THE 40S NORTH AND LOWER 50S SOUTH WEDNESDAY.
SOME MOISTURE WILL BE PULLED NORTHWARD...BUT IT APPEARS THAT ANY
PCPN SHOULD STAY JUST A LITTLE EAST OF OUR FORECAST AREA. COLD FRONT
WILL MOVE THROUGH ALL OF THE AREA BY WEDNESDAY EVENING...AND HIGH
PRESSURE IS FORECAST TO BUILD DOWN FROM CANADA INTO THE NORTHERN
AND CENTRAL PLAINS.
AS CLOSED LOW OFF THE COAST OF BAJA EJECTS EASTWARD AND MERGES
WITH THE FLOW...ENERGY WILL INDUCE A DECENT LOW PRESSURE SYSTEM FOR
THE SOUTHERN PLAINS. JUST HOW FAR NORTH THE PRECIPITATION WILL MAKE
IT IS A CONCERN. 12Z GFS SHOWED A BAND OF SNOW DEVELOPING OVER
SOUTHEAST NEBRASKA THURSDAY WITH ELEVATED FRONTOGENESIS AND DECENT
OMEGA VALUES. IT DOES APPEAR THAT THERE WILL BE SOME DRY AIR TO
OVERCOME BELOW ABOUT 750 MB. THE ECMWF ALSO BRINGS SNOW INTO PARTS
OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA FOR THURSDAY INTO EARLY
THURSDAY EVENING. ONE TO THREE INCHES OF SNOW SEEMS POSSIBLE...
ESPECIALLY SOUTH OF INTERSTATE 80. LIGHTER AMOUNTS COULD OCCUR
FARTHER NORTH. ANOTHER SYSTEM WILL PROBABLY BRING AT LEAST SOME
LIGHT SNOW TO THE NORTHERN AND CENTRAL SECTIONS OF THE FORECAST
AREA BY LATE THURSDAY NIGHT OR FRIDAY...WITH AROUND AN INCH OF SNOW
MAINLY FOR NORTHEAST NEBRASKA.
TEMPERATURES THURSDAY SHOULD TOP OUT AT 25 TO 30 NORTH AND MOSTLY
AROUND 30 TO 35 SOUTH. COLDER AIR IS EXPECTED TO PUSH IN FROM THE
NORTHWEST FRIDAY.
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY.
DETERMINISTIC/ENSEMBLE MODELS IN DECENT AGREEMENT LARGE SCALE ZONAL
FLOW GENERALLY PREVAILING THRU THE FCST PD. INITIAL FEATURE OF
INTEREST IS CANADIAN VORT LOBE MOVING THRU THE DAKOTAS AND UPPER
MIDWEST FRIDAY NIGHT/SATURDAY. BRUNT OF DYNAMIC FORCING ASSOCIATED
WITH THIS SYSTEM PROGGED TO BE FOCUSED OVER THE ERN DAKOTAS/MN.
HOWEVER...STILL A SMALL CHANCE FOR SN OVER THE CWA MORE RELATED
TO RATHER STRONG 290K-295K UPGLIDE/OVERRUNNING SITUATION DURING THIS
TIME. AXIS OF FAVORABLE MID LAYER QG FRONTOGENESIS ORIENTED NW-SE
JUST WEST OF THE CWA AND THEREFORE HAVE BUMPED POPS UP JUST A BIT
SOUTH FRIDAY NIGHT AND INTRODUCED SLGT POPS ON SATURDAY. OTHERWISE
HAVE OPTED TO KEEP DRY FCST GOING SATURDAY NIGHT THRU TUESDAY. TOO
MUCH UNCERTAINTY REGARDING HOW MUCH OF AN INFLUENCE POTENT LATE PD
SRN BRANCH SYSTEM WILL BE OVER THE CNTRL PLAINS. THE LATEST ECM
ADVERTISING CLOSED UPPER LOW STRENGTHENING WHEN IT EXITS THE GREAT
BASIN LATE SUNDAY NIGHT THEN QUICKLY ZIPS EWD ACROSS THE SRN GULF
STATES. MEANWHILE THE GFS/CMC OFFERING A MUCH FASTER SOLUTION
DEPICTING AN OPEN WAVE RACING PAST THE SRN PLAINS SUNDAY EVENING AND
MAKING IT TO THE SERN COASTAL STATES MONDAY EVENING. ONE THING
THOUGH THE GFS/ECM/CMC ALL AGREE ON IS NO SIGNIFICANT GULF MOISTURE
RETURN REACHING THE CNTRL PLAINS UNTIL TUESDAY...THUS LENDING MORE
SUPPORT FOR FAVORING DRY FCST DAYS 5-7.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
SFC HIGH PRESSURE WILL CONTINUE TO SHIFT TO THE EAST THIS AFTERNOON
WITH RETURN SOUTH FLOW INCREASING ACRS THE TAF SITES. THE LOW LEVEL
JET WILL INCREASE ACRS NORTHEAST NEBRASKA THIS AFTERNOON AND TONIGHT
AND SHOULD PROVIDE A FEW HOURS WHERE THE 10 TO 15KT WINDS AT KOFK
WILL BE SLIGHTLY STRONGER THAN KOMA AND KLNK AND GUST TO 20KTS.
WEDNESDAY MORNING...A SECOND AREA OF STRONGER LOW LEVEL WINDS WILL
DEVELOP OVER KANSAS AND SPREAD INTO SOUTHEAST NEBRASKA. THESE
SHOULD MOSTLY REMAIN TO THE SOUTH OF KLNK AND KOMA. VFR CONDITIONS
WILL CONTINUE WITH SOME PATCHY MID AND HIGH CLOUDS. MUCH HIGHER
DEWPOINTS WILL BE DRAWN NORTHWARD WEDNESDAY MORNING. SOME RISK OF
MVFR CONDITIONS WEDNESDAY MORNING...AHEAD OF THE COLD FRONT...BUT
WITH LOW CONFIDENCE THAT THESE LOW CLOUDS WILL DEVELOP FAR ENOUGH TO
WEST...THUS DID NOT MENTION AT THIS TIME.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM....DEE
AVIATION...ZAPOTOCNY