FXUS63 KOAX 300958
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
358 AM CST SUN JAN 30 2011
.DISCUSSION...
SYNOPSIS...00Z UPPR AIR ANLYS INDCD THE TWO MAIN SYSTEMS OF
INTEREST FOR THE CWA WERE STARTING TO MOV INTO THE WRN US. THE
FIRST WAS LOCATED OVR THE ERN PAC ASSOCIATED WITH A 90 M H5 HEIGHT
FALL AND A 85 KT H3 JET. THE NRN STREAM SYSTEM WAS LOCATED OVR BC.
DOWNSTREAM FM THE TWO SYSTEMS...GENERALLY ZONAL UPPR LVL FLOW
PERSISTED OVR THE CNTRL PLAINS. MOISTURE WAS STARTING TO DEEPEN
OVR DEEP S TX AT H85 WITH A DP OF +9 AT KBRO. 09Z SFC ANLYS INDCD
SFC RIDGE FM ERN SD THRU ERN NEB.
FORECAST...SFC RIDGE AXIS WL REMAIN NEARLY STATIONARY THRU THE DAY
TODAY. LATEST IR IMAGERY INDCS A GOOD DEAL OF BREAKS IN THE
STRATUS DECK AND LATEST MODEL GUIDANCE WLD INDC THIS MAY CONT THRU
THE DAY. OTHERWISE LITTLE IN THE WAY OF SENSIBLE WX IS EXPECTED.
TONIGHT THE UPPR LVL FLOW STARTS TO BACK TO THE WEST AND THEN
EVENTUALLY SW ON MON. THIS WL LEAD TO WAA AND INCREASING
FRONTOGENESIS. THIS CURRENTLY LOOKS TO BE MOST EFFECTIVE TO OUR N
IN ERN SD INTO MN/NRN IA. THUS HAVE REMOVED GOING POPS IN ALL BUT
OUR FAR NORTHERN TWO COUNTIES WHERE LIKELY POPS REMAIN AFTER
MIDNIGHT. SFC INVERTED TROF WL START TO DVLP OVER WRN IA TOWARD
12Z ON MON AS LO LVL WAA INCREASES IN THIS AREA. POINT FORECAST
SOUNDINGS INDC MOISTURE DEPTH WL INCREASE LATE TONIGHT WITHOUT
MID-LVL SATURATION...AND THUS SOME PATCHY FZDZ WL BE POSSIBLE
ALONG AND E OF THE RIVER BUT AMOUNTS AND IMPACT ARE EXPECTED TO BE
LIGHT. MAY ACTUALLY SEE SOME RISE IN THE TMPS OVER WRN IA
OVERNIGHT AS THE INVERTED TROF DVLPS. DURING THE DAY ON MON THE
TWO PREVIOUSLY MENTIONED WRN US SYSTEMS WL START TO ADVANCE EWD
THRU THE ROCKIES. MODELS CONT TO STRUGGLE WITH HOW THESE TWO
SYSTEMS WILL INTERACT WITH EACH OTHER THRU THE SHORT TERM PERIODS.
THE EC CONTS TO BE THE FARTHEST NORTHWEST AS IT EJECTS THE SRN
STREAM SYSTEM INTO THE PLAINS. THE GEM WAS DISCOUNTED AS A SRN
STREAM OUTLIER AND THE GFS WAS IN THE MIDDLE OF THE ROAD. GFS
ENSEMBLES INDC A LITTLE FARTHER NORTHWEST TRACK THAN THE
OPERATIONAL RUN...BUT NOT A SIGNIFICANT DIFFERENCE. THUS WL RUN
WITH A EC/GFS COMPROMISE FM MON THRU WED.
AS LARGE-SCALE Q-G FORCING INCREASES DURING THE DAY ON MON...THIS
WL HELP TO INCREASE THE FRONTAL CIRCULATION OVER THE FA. ATTM...IT
APPEARS THE FRONTOGENESIS AROUND 600 OR 650 MB WILL BE THE MOST
EFFECTIVE FOR US DURING THE DAY ON MON. THUS THE BEST LIFT WLD BE
ALNG AND N OF INTERSTATE 80...AND HAVE GONE WITH CAT POPS FOR
THIS AREA DURING THE DAY ON MON. TMPS ON MON WL BE STEADY OR
SLOWLY FALLING W OF THE INVERTED TROF /NAMELY OVR NE NEB/ WHILE
TMPS WL CONT TO INCREASE TO THE E OF THE INVERTED TROF. AS THE
1050 MB SFC HI OVR THE NRN PLAINS STARTS TO SAG SWD ON MON
AFTN...WE SHLD START TO SEE THE WINDS INCREASE AND BLOWING SNOW
BECOME AN ISSUE BY MON AFTN OVR NE NEB. POINT FORECAST SOUNDINGS
ALSO INDC AN IMPRESSIVE DEPTH TO THE DENDRITIC SNOW GROWTH ZONE
OVR NE NEB ON MON AND THIS WL LIKELY LEAD TO ACCUMULATING
SNOWFALL. THIS PATTERN OF BLOWING SNOW AND DEEP DENDRITIC ZONE
STARTS TO SHIFT A LITTLE FARTHER SOUTH ON MON NIGHT...BUT
WIDESPREAD SNOW IS EXPECTED TO CONT MOST EVERYWHERE. ALTHOUGH WE
MAY TEND TO SEE SOME DECREASE IN SNOWFALL INTENSITY AFTER MIDNIGHT
ON MON...THIS SHLD ONCE AGAIN PICK UP /ESPECIALLY OVER THE SRN
2/3RD OF THE FA/ AS THE SRN STREAM SYSTEM STARTS TO EJECT EWD THRU
KS AND MO INCREASING THE FORCING FOR LARGE-SCALE ASCENT. WITH THE
INVERTED TROF PROGGED TO BE JUST E OF THE FA AT THIS TIME...THE
CWA SHLD SEE WINDY CONDS MOST EVERYWHERE WITH STEADY TMPS FROM
AROUND 0 IN THE NW AND NEAR 10 SE. WITH THE NEW SNOW FALLING ON
TOP OF A CRUSTY SNOW PACK...THE WINDY CONDS ON TUES ARE EXPECTED
TO EASILY LEAD TO WIDESPREAD BLOWING SNOW THRU THE DAY. LIFT WL
START TO DECREASE ON TUES AFTN AND EVNG AS THE SYSTEM PULLS OFF TO
THE E AND SNOW WL END...BUT BLOWING SNOW CLD CONT ON TUESN NIGHT.
GIVEN ALL THE ABOVE FACTORS HAVE ELECTED TO ISSUE A WINTER STORM
WATCH FOR SE 2/3 OF THE FA WHERE WE HAVE THE HIGHEST SNOWFALL
ACCUMULATIONS. ALTHOUGH WE MAY NOT MEET OFFICIAL WARNING CRITERIA
IN THE ENTIRE AREA OF THE WATCH/6 IN IN 12 HR OR 8 IN IN IN 24/...WE
THOUGHT THE COMBINATION OF THE WIDESPREAD BLOWING SNOW...BITTERLY
COLD WIND CHILLS....AND FAIRLY SIG AMOUNTS OF SNOW WARRANT A
HEADLINE. WE CHOSE THE WINTER STORM WATCH OVER THE ADVRY B/C OF
THE UNCERTAINTY OF THE SYSTEM AND OUR FORECAST NEAR OR SLIGHTLY
BELOW WARNING LEVELS. ANY DEVIATION TO THE TRACK WL CERTAINLY
HAVE SIG CHANGES TO THE FORECAST...BUT OUR CONFIDENCE IS HIGH THAT
TRAVEL WL BE IMPACTED DURING THIS TIME. SOME OF THE WATCH MAY
BECOME AN ADVISORY AT A LATER TIME WHEN CONFIDENCE OF WHERE
INCREASES. AN ADVSRY WL ALSO BE NEEDED LATER FOR NE NEB FOR SNOW
AND BLOWING SNOW...BUT OUR FORECAST AMOUNTS WERE LOWER IN THIS
AREA. WE WILL HIGHLIGHT THE UNCERTAINTY IN THE WATCH PRODUCT.
OTHERWISE...FORECAST WISE WE HAVE LOWERED HIGHS/LOWS THRU
THURS...BUT NO CHANGES PAST THIS TIME.
BOUSTEAD
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
CIGS WILL FLUCTUATE BETWEEN SCT-BKN AT LOW-END MVFR TO IFR RANGES
THROUGH MUCH OF THIS MORNING...BEFORE A MORE SOLID OVC DECK BLANKETS
ALL TAF SITES TODAY/TONIGHT. CIGS WILL LIKELY START AS MVFR TODAY
BEFORE DESCENDING INTO IFR TONIGHT. WINDS WILL RANGE FROM NRLY TO
NERLY WITH SPEEDS UNDER 10KTS.
MAYES
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY EVENING
FOR NEZ045-051>053-066>068-089>093.
IA...WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY EVENING
FOR IAZ055-056-069-079-080-090-091.
&&
$$