FXUS63 KOAX 040924
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
324 AM CST FRI MAR 4 2011
.DISCUSSION...
SYNOPSIS...00Z UPPR AIR ANLYS INDCD 100 KT H3 JET MOVG INTO NRN
CA. DOWNSTREAM...80-90 KT JET H3 JET EXTNDD FM CO INTO WRN KS.
BOTH THESE JETS WERE ASSOCIATED WITH SHRTWV ENERGY SEEN AT H5 WITH
40 M HEIGHT FALLS INDICD OVER CO. THE MAJORITY OF THE COLD AIR AT
H7 WAS LOCATED OVR CANADA...BUT SOME THERMAL GRADIENT WAS NOTED
OVER SW NEB/WRN KS INTO CO. THE ATMOSPHERE AT H85 WAS GENERALLY
DRY ACRS THE PLAINS WITH THE 0 C DEW POINT CONTOUR FM OKC TO TOP
TO OMA. 08Z SFC ANLYS INDCD LO PRES OVR WRN TX WITH A CDFNT THRU
ERN KS AND CNTRL IA.
FORECAST...THE SHRTWV TROFS OFF TO THE WEST WILL BE MAKING EWD
PROGRESS THRU THE FA TODAY...THEN WILL AMPLIFY OVR THE GREAT LAKES
TONIGHT. CURRENT PRECIP ON THE REGIONAL RADAR MOSAIC IS LOCATED
NEAR THE H7 THERMAL GRADIENT...AND IS IN THE LEFT EXIT REGION OF
THE H3 JET. THIS WILL GENERALLY SHIFT EWD THIS MRNG...BUT DRY MID
LVL AIR IS LIMITING MANY OF THE RETURNS FM REACHING THE GROUND.
THUS FOR THE MORNING WILL JUST HAVE A SCHC POP IN THE S FOR THIS
INITIAL BAND. THE GFS AND NAM ARE THEN IN DISAGREEMENT IN THE
AMOUNT OF FORCING TO MOV ACRS THE FA THIS AFTN ASSOCIATED WITH THE
SECOND SHRTWV TROF. BOTH MODELS HAVE FAVORABLE LARGE-SCALE SUPPORT
FOR ASCENT SEEN IN THE H5 TO H3 DIV-Q AS WELL AS DECENT PV
ADVECTION ON THE TROP SFC. BUT THE GFS ENHANCES A MID-LVL /AROUND
H6/ FRONTOGENESIS AREA THIS AFTN. THIS ALONG WITH A WEAKLY STABLE
ATMOSPHERE LEADS TO MORE PRECIP IN THE GFS MODEL. ANALYSIS OF
OTHER GUIDANCE IS OF LITTLE HELP THE THE GEM SIMILAR TO THE NAM
AND THE EC SIMILAR TO THE GFS. 03Z SREF INDCS THE GFS MAY HAVE THE
RIGHT IDEA HERE...AND THUS WILL TENTATIVELY LEAN IN THAT DIRECTION.
THUS HAVE INCREASED AFTN POPS GENERALLY ALNG AND S OF I-80 AND E
OF HIGHWAY 77. ALTHOUGH THERE IS SOME VERY SLIGHT POTENTIAL FOR A
MIX IF PRECIP FELL THIS BEFORE 15Z...FEEL ANYTHING AFTER 15Z WL BE
ALL RAIN AT LEAST THRU 21-22Z. AFTER THAT TIME MAY SEE A FEW
FLAKES MIXING IN OR BECOME THE DOMINATE PRECIP TYPE BEFORE ENDING
EARLY THIS EVNG. NO REAL ACCUM IS EXPECTED. OTHERWISE HAVE LOWERED
GOING HIGHS TODAY WITH THE STG CAA OF MODIFIED CANADIAN AIR. ALSO
LOWERED LOWS TONIGHT AS WELL...BUT ONLY TO THE UPPER ENVELOPE OF
GUIDANCE DUE TO EXPECTED CONTD MIXING AND CLDS.
SAT LOOKS DRY AND MOSTLY SUNNY. SHRTWV WV ENERGY WILL THEN START
TO SPILL INTO THE WRN US ON SAT NIGHT AND THRU THE DAY ON SUN.
AS THIS OCCURS WAA WL INCREASE ACRS THE PLAINS...AND THERE IS
SOME HINT AT PRECIP POSSIBLY STARTING AS EARLY AS SUN. THIS LOOKS
TO MAINLY INITIALLY AFFECT THE NRN PLAINS...BUT WL MAINTAIN THE LO
CHC POPS IN OUR NRN FA. THE WAA PATTERN WILL CONT INTO MON AND MAY
ALLOW FOR SOME LIGHT SNOW TO GET GOING OVER THE NRN CWA ON
MON OR A LIGHT SHOWER ELSEWHERE...BUT THE MAIN SYSTEM STILL LOOKS
TO AFFECT THE REGION ON TUES INTO WED. GIVEN THE MODEL CONSISTENCY
AND AGREEMENT...WENT AHEAD AND BOOSTED POPS INTO THE LIKELY CAT
FOR THESE PERIODS. LOOKS LIKE THE BEST SHOT AT SIG SNOWFALL WILL
BE OVER THE NRN CWA WITH A MIX ELSEWHERE WITH COLDER AIR SPILLING
IN BEHIND THE SYSTEM.
BOUSTEAD
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
AN UPPER LEVEL TROUGH WILL MOVE THROUGH THE TAF SITES THIS MORNING.
WHILE SOME PRECIPITATION MAY FALL...PRECIPITATION INTENSITIES WILL
NOT BE STRONG ENOUGH TO SIGNIFICANTLY REDUCE VISIBILITIES. LATEST
MODEL GUIDANCE SHOWS CURRENT PREDOMINANT MID/HIGH CLOUD DECK WILL BE
REPLACED BY A LOWER DECK BY THIS AFTN...LIKELY IN THE LOW-MVFR RANGE.
EXPECT THESE CLOUDS TO LINGER THROUGH THE TAF PERIOD.
PEARSON
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$