FXUS63 KOAX 211931
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
231 PM CDT TUE SEP 21 2010
.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT.
GOING FCST IS IN PRETTY GOOD SHAPE AND HAVE ONLY MADE TWEAKS HERE AND
THERE. PCPN CHANCES CONTINUE TO REVOLVE AROUND A MEANDERING SFC BNDRY
COUPLED WITH UPPER LEVEL SUPPORT FROM PAC NW SHORTWAVE TROF
EVENTUALLY MOVING THRU THE NRN PLAINS. AFTN OBS SHOWING THERMAL BNDRY
EXTENDING ACROSS ERN IA/SERN NEB/WRN KS. HAVE PRETTY MUCH USED A
BLEND OF NAM/GFS/CMC/ECM BNDRY LYR MOIST CONVG AS GUIDE WHERE/WHEN TO
PLACE THUNDER POPS. EXPECT BNDRY TO SETTLE ALONG THE NEB/KS BORDER
LATER TONIGHT THEN SLOWLY BEGIN TO DRIFT BACK NORTH AS A WARM FRONT
ON WEDNESDAY REACHING THE SD/NEB BORDER BY LATE AFTN. MEANWHILE SFC
LOW PRESSURE ORIGINATING NEAR THE NEB PANHANDLE WILL LIFT TO THE
UPPER MIDWEST ON THURSDAY AND DRAG ATTENDANT COLD FRONT INTO THE
CNTRL PLAINS. THE FRONT SHOULD QUICKLY EXIT THE CWA LATE THURSDAY
NIGHT WITH RELATIVELY WEAK CAA FILTERING IN. LLVL MOIST RETURN IS
QUITE STRONG LEADING UP TO FROPA...SO SEEMS PROBABLY FOR LOCALLY
HEAVY RAINFALL.
REGARDING TONIGHT...NAM AND GFS INDICATE ENVIRONMENT WILL REMAIN
UNSTABLE OVER THE CWA...MUCAPES 1500J/KG...LI -4 TO -5. MODELS ALSO
ADVERTISING DECENT SHEAR AS IT SETS UP ALONG THE KS/NEB BORDER...SO
CANNOT DISCOUNT SVR STORM POTENTIAL LATER THIS EVENING MAINLY SOUTH
OF I-80.
.LONG TERM...FRIDAY THROUGH TUESDAY.
PCPN POTENTIAL IN THE EXTENDED PDS STILL COMPLICATED AND DIFFICULT
TO PIN DOWN DESPITE LATEST MODEL SOLUTIONS IN SLIGHTLY BETTER
AGREEMENT COMPARED TO YESTERDAYS RUN. THE GFS HAS COME AROUND TO
YESTERDAYS ECM/CMC DEPICTING SHORTWAVE TROF DROPPING OUT OF SRN
CANADA INTO THE UPPER MIDWEST FRIDAY NIGHT. BUT NOW LATEST ECM IS
TRENDING TOWARD A WEAKER AMPLITUDE WAVE...WHILE THE CMC IS QUITE
SIMILAR TO ITS PREVIOUS RUN. AT THIS POINT...FEEL IT IS REASONABLE TO
KEEP TOKEN 20S GOING FRIDAY NIGHT. OTHERWISE WILL OPT FOR DRY FCST
THE REST OF THE FCST PD. HPC IS FAVORING LARGE SCALE PATTERN
TRANSITIONING TO AN UPPER RIDGE BECOMING ESTABLISHED OVER THE CONUS
EARLY NEXT WEEK. REMOP HIGH PREDICTABILITY LENDING SUPPORT TO THIS
SCENARIO. AS FOR TEMPS...GENERALLY HAVE MID/UPPER 70S FOR THE CWA
WHICH IS ROUGHLY NEAR NORMAL FOR THIS TIME OF THE YEAR.
&&
.AVIATION...
18Z TAFS
GENERALLY VFR CONDS EXPECTED THROUGH THE EVNG HOURS AT ALL TAF SITES
WITH DRY CONDS. SFC CDFNT TO THE S OF THE TERMINALS WL START TO
RETREAT TO THE N OVERNIGHT ALNG WITH MODERATE WAA. THIS IS LIKELY TO
ALLOW FOR A STRATUS DECK TO DVLP AT ALL THREE SITES AFTER 08Z. MVFR
CIGS/VISBY WL LIKELY GO DOWN TO IFR AT OFK/LNK TOWARD 12Z BUT MAY
STAY IN MVFR AT OMA. IFR/MVFR CONDS EXPECTED TO CONT INTO MID MRNG
BEFORE CONDS IMPROVE AT OMA/LNK...BUT MAY HOLD ONTO 18Z AT OFK.
SERLY LO LVL WNDS WL ALSO INCREASE DURING THE MRNG AT ALL TAF SITES.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
DEE/JB