FXUS63 KOAX 310955
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
355 AM CST MON JAN 31 2011
.DISCUSSION...
SYNOPSIS...00Z UPPR AIR ANLYS INDCD THE TWO MAIN SYSTEMS OF
INTEREST WERE NOW ONSHORE AND OVER THE WRN US. THE STREAM STREAM LOW
LOCATED OVR THE SRN GREAT BASIN ASSOCIATED WITH 100 M H5 HEIGHT
FALLS. THE NRN STREAM SYSTEM WAS LOCATED OVR SRN ALBERTA AND
ASSOCIATED WITH 60 M H5 HEIGHT FALLS. DOWNSTREAM FM THE
SYSTEMS...ZONAL FLOW EXTNDD ACRS THE PLAINS. GREATEST H7 THRML
GRADIENT EXTNDD FM SRN MT INTO CNTRL MN. H85 LO WAS LOCATED OVR WY
WITH ARCTIC FNT NEWD THRU ND. 09Z SFC ANLYS INDCD LO PRES OVR NRN
CO. AN INVERTED TROF WAS DVLPG FM ERN KS INTO WRN IA.
FORECAST...DIFFICULT FORECAST THIS MRNG AS WE STILL FEEL THE
MODELS STILL DO NOT HAVE A FULL HANDLE ON HOW THE TWO WRN SYSTEMS
WILL INTERACT OVER THE NEXT 48 HOURS. LITTLE OVERALL CHANGE IN THE
MODELS FM 00Z WITH THE GFS STILL FARTHER S AND FASTER...AND THE
EC STILL FARTHER NW AND SLOWER. GIVEN THE SUPPORT FOR THE EC FM
THE NAM/GEM AND ENSEMBLES...WILL CONT LEAN A LITTLE HEAVIER ON
THIS MODEL...BUT A BLEND WAS REALLY USED. STG MID LVL THRML
GRADIENT OVER THE NORTHERN PLAINS WILL DROP SWD TODAY AND INTO THE
FA THIS AFTERNOON. AT THE SAME TIME...UPPR LEVEL JET FM THE CNTRL
ROCKIES INTO THE NRN PLAINS WILL SHIFT EWD LEAVING THE FA IN THE
RIGHT REAR ENTRANCE REGION OF THIS JET. THUS ON THE SYNOPTIC
SCALE...THE ATMOSPHERE SHLD FAVOR ASCENT BY THIS AFTERNOON. THIS
COUPLED WITH THE STRONG THERMAL GRADIENT WILL LIKELY LEAD TO AN
EFFECTIVE FRONTAL CIRCULATION BY LATE THIS AFTERNOON. THUS
ALTHOUGH WE ARE LIKELY TO SEE A LITTLE LIGHT SNOW THIS MORNING IN
THE NW...THIS SHLD INCREASE IN COVERAGE AND INTENSITY THROUGH THE
AFTN WITH A NICE LITTLE E-W BAND SETTING UP BY THIS EVENING. UNTIL
THEN...WE SHOULD SEE FZDZ FAIRLY WIDESPREAD OVER THE SRN/ERN CWA
AS DEEPER LO-LVL MOISTURE /SEEN ON THE KTWX RADAR AT 09Z/ SHIFTS
NEWD THRU THE AREA. THUS WL CONT TO MENTION THE FZDZ FOR THE MRNG
HOURS ALONG WITH SOME FOG. BEST SNOWFALL RATES ASSOCIATED WITH
THIS INITIAL JET CIRCULATION WILL LIKELY BY FROM AROUND 21-06Z
BEFORE THE UPPR LVL JET SHIFTS EWD AND THE FRONTAL CIRCULATION
BREAKS DOWN. THIS IS WHEN WE ARE LIKELY TO SEE OUR GREATEST
ACCUMULATIONS IN THE NW FA WHERE 2-4 INCHES ARE LIKELY TO FALL. AS
INVERTED TROF SHARPENS TODAY...SHLD SEE WINDS INCREASE BEHIND THE
TROF /OVR NE NEB/ LEADING TO SOME BLOWING AND DRIFTING BY LATE
THIS AFTN.
A LULL IN THE STEADY SNOW IS THEN EXPECTED FM AROUND 09-15Z ON
TUES AS THE JET ASSOCIATED WITH THE SRN STREAM SYSTEM ROUNDS THE
BASE OF THE TROF AND ACCELERATES TO THE NE. LARGE-SCALE FORCING WL
ONCE AGAIN INCREASE WITH PVA ON THE TROP SFC NOTED FM ALL MODELS.
THIS WL ONCE AGAIN LEAD TO DEFORMATION AND THEN FRONTOGENESIS
ACRS OUR FA. ATTM IT APPEARS THE WEAKEST STABILITY...BEST
FRONTOGENESIS ARND H6...AND BEST LARGE-SCALE FORCING WL LINE UP FM
AROUND BIE TO AFK TO RDK AND POINTS SOUTH. THIS FORCING SHOULD
CONT INTO TUES NIGHT AS THE 295 KE SFC INDCS A WEAK TROWAL DVLPG
FM SRN IA BACK INTO SE NEB/NE KS AT THIS TIME. THIS IS LIKELY WHEN
OUR SRN FA IS LIKELY TO SEE THE HEAVIEST SNOWFALL. THE CNTRL CWA
/ALNG THE I-80 CORRIDOR/ IS LIKELY TO SEE SOME ACCUMULATION FM
BOTH PERIODS WHICH WL ADD UP AS WELL. EC IS MUCH STRONGER WITH THE
SFC LO THAN OTHER MODELS...BUT IS NOT OUT OF THE QUESTION. THIS
ALSO LEADS TO STRONGER WINDS WITH A GOOD 50 KT AT 925 MB ON TUES
INDCD FM THE EC. POINT FORECAST SOUNDINGS THOUGH INDC THAT THE
LOW-LEVEL LAPSE RATES ARE ONLY MARGINAL FOR MIXING THIS TYPE OF
WIND TO THE SFC...AND THIS IS FAIRLY WELL AGREED UPON.
THUS...ALTHOUGH WE ARE LIKELY TO SEE WINDY CONDS ON TUES/TUES
NIGHT...WE DOUBT IF WE CAN MIX DOWN THE STRONGEST OF THE WINDS. SO
ATTM...IT APPEARS WE WILL HAVE CONSIDERABLE BLOWING AND DRIFTING
OF NEW SNOW...BUT WIDESPREAD AND SUSTAINED BLIZZARD CONDITIONS
APPEAR UNLIKELY ATTM. HELD ONTO THE SNOW IN THE THRU TUES
NIGHT...BUT HAVE WED DRY WITH NO CHANGES TO THE FORECAST PAST
THUR.
AS FAR AS HEADLINES. HAVE REDUCED SNOWFALL AMOUNTS MOST
AREAS...BUT ESPECIALLY IN THE NW WHERE WE NOW HAVE 2-4 INCHES
GOING. ALTHOUGH WE WILL SEE SOME BLOWING AND DRIFTING...WE
GENERALLY DO NOT FEEL WARNING CONDITIONS WILL BE MET FOR AREAS
SUCH AS OLU/OFK/LCG. NEVERTHELESS...SINCE CONDS ARE NOT EXPECTED
TO BE GREAT FOR TRAVELING WE WILL LEAVE THE WARNING GOING. DID
ADJUST TIMING IN THE NW TO END EARLIER THOUGH ON TUES EVNG.
WARNING STILL LOOKS ON TRACK FOR I-80 AND S THOUGH WITH NEAR
WARNING LEVEL SNOWS AND WIND. ADJUSTED THE TIMING THOUGH IN THE
FAR S TO START AT 00Z AS LITTLE SNOW WILL FALL TODAY IN BIE/FNB.
THESE AREAS THOUGH WILL SEE SOME FZDZ TODAY THAT MAY CAUSE SOME
SLICK SPOTS THOUGH.
BOUSTEAD
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
IFR LIFR CONDITIONS ARE EXPECTED AT ALL TAF SITES THROUGH THE
CYCLE...WITH CIGS BELOW 1000 FT AND IN MANY LOCATIONS BELOW 500 FT.
FOG AND FREEZING DRIZZLE ARE POSSIBLE IN THE EARLY MORNING HOURS
TODAY...REDUCING VIS TO 1/2SM-1SM...WITH THE POTENTIAL TO CONTINUE
INTERMITTENTLY INTO THE LATE MORNING AT KLNK/KOMA. SNOW WILL
OVERSPREAD THE AREA FROM NORTHWEST TO SOUTHEAST THROUGH THE
DAY...AFFECTING KOFK BY EARLY MORNING AND KOMA/KLNK BY LATE
MORNING. HEAVIEST SNOW IN THIS TAF CYCLE IS EXPECTED TO BEGIN IN
THE LATE AFTERNOON AT KOFK AND IN THE EARLY EVENING AT
KOMA/KLNK...CONTINUING UNTIL LATE EVENING AT KOFK AND EARLY
OVERNIGHT AT KOMA/KLNK. INCREASING WINDS THIS EVENING WILL ALSO
CREATE BLOWING SNOW CONDITIONS...WITH WINDS SHIFTING FROM
NORTHEASTERLY TO NORTHWESTERLY AS AN INVERTED TROUGH SLOWLY MOVES
THROUGH. WIND SHIFT/INCREASE WILL OCCUR AT KOFK AROUND MIDDAY...AT
KLNK BY LATE AFTERNOON...AND AT KOMA IN THE EVENING OR LATER.
MAYES
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WARNING FROM NOON TODAY TO 6 AM CST WEDNESDAY FOR
NEZ015-018-030>034-042>045-050>053-065>067.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST
WEDNESDAY FOR NEZ068-078-088>093.
WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT CST TUESDAY
NIGHT FOR NEZ011-012-016-017.
IA...WINTER STORM WARNING FROM NOON TODAY TO 6 AM CST WEDNESDAY FOR
IAZ043-055-056-069-079-080.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST
WEDNESDAY FOR IAZ090-091.
&&
$$