Issued by NWS Omaha/Valley, NE
000 FXUS63 KOAX 092011 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 311 PM CDT MON MAR 9 2009 .SHORT TERM...TONIGHT THROUGH THURSDAY. 88 MOSAIC SHOWING AREA OF PCPN STREAMING ACROSS ERN KS ALONG AN INVERTED TROF EXTENDING FROM SFC LOW PRESSURE IN ERN CO TO MN. ACTIVITY ASSOCIATED WITH UPPER DISTURBANCE LIFTING OUT OF THE SRN ROCKIES AND INTO THE CNTRL PLAINS. OTHERWISE...LARGE SCALE FLOW HAD A STRONG UPPER TROF OVER THE WRN CONUS WITH SEGMENTED PIECES OF ENERGY...ONE OVER THE PAC NW AND THE OTHER DIGGING SWD THRU THE GREAT BASIN. ALSO...HEALTHY PLUME OF MOISTURE WAS PUSHING INTO THE CENTRAL STATES VIA SRN STREAM FLOW. DIFFICULT FCST ON TAP THE NEXT 48HRS TRYING TO PIN DOWN PCPN TIMING AS WELL AS TYPE WITH FAST MOVING VORT ENERGY. NAM/GFS/ECM SEEM TO BE IN REASONABLE AGREEMENT THAT A MIXED BAG OF PCPN WILL BE ON TAP TONIGHT THROUGH TUESDAY MORNING. AFOREMENTIONED LEAD IMPULSE IN KS WILL QUICKLY EJECT NORTHEAST TO THE UPPER MIDWEST FOLLOWED BY A MORE POTENT SYSTEM BRINGING IN A SECONDARY SHOT OF COLDER AIR TO THE REGION. FOR TONIGHT...APPEARS FZRA/SN POSSIBLE NRN CWA WITH AREAS OF RA AND EMBEDDED CONVECTION ALONG AND SOUTH OF I-80. BY TUESDAY MORNING ENOUGH COLD AIR WILL HAVE PENETRATED INTO THE CWA FOR POSSIBLE SNOW ACCUMULATIONS IN THE NRN CWA. WITH BEST DYNAMIC LIFT PROGGED TO REMAIN OVER THE DAKOTAS AND MN...THE NRN CWA SHOULD BE SPARED FROM ANY SIGNIFICANT ACCUMULATIONS AND ANTICIPATE GENERALLY AN INCH OR SO BY TUESDAY AFTERNOON. GUSTY NORTHWEST WINDS MAY ALSO INDUCE AREAS OF BLOWING SNOW. GIVEN POTENTIAL FOR MIXED BAG OF PCPN AND POSSIBLE SN/BLSN...THINK AN ADVISORY IS REASONABLE. OTHERWISE DRY AND CHILLY CONDITIONS TUESDAY THRU THURSDAY. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY. EXTENDED FORECAST BEGINS WITH CWFA BASICALLY IN BETWEEN NRN STREAM UPPER RIDGE AND SRN STREAM TROUGH. WILL KEEP FCST DRY IN THU FRI-SUN PD AS IT STILL APPEARS...BASED ON 12Z OPERATIONAL GFS/00Z ECMWF AND 00Z GFS ENSEMBLE MEAN THAT THE TROUGH AND QPF REMAINS MOSTLY TO OUR S. MADE LTL CHANGES TO TEMPS THOSE PDS...WITH MAX TEMPS POSSIBLY A LTL BELOW LATEST MEX GUIDANCE FRI DUE TO MORE CLOUDS PER GFS/GFS ENSEMBLE MEAN...WITH TEMPS CLIMBING A LTL ABV NORMAL SAT/SUN AS SRLY LOW LVL FLOW IS FCST TO INCREASE A BIT DURING THAT TIME ALTHOUGH FCST COULD BE IMPACTED NEGATIVELY BY CLOUDS IF TROUGH WOULD OPEN UP FARTHER N THAN FCST. DECENT AGREEMENT AMONG 12Z GFS AND 00Z ECMWF/CMC IN BRINGING A FAIRLY STRONG UPPER TROUGH/FRONT ACROSS CWA IN SUN NGT/MON PD. INCLUDED SMALL POPS ATTM DURING THAT TIME WITH THE UNDERSTANDING THAT ADJUSTMENTS UPWARD COULD BE MADE LATER IF THIS TREND CONTS. ALSO FCST TEMPS BELOW MEX WHICH WAS PROBABLY INFLUENCED TOO MUCH BY CLIMO THEN. && .AVIATION... FOR TAF SITES KOFK/KOMA/KLNK THRU 10/18Z. COMPLEX WEATHER AFFECTING TAF SITES THIS CYCLE AS LOW PRESSURE SYSTEM SLIDES ACROSS THE PLAINS. STRATUS/VIS HAVE CLEARED AT KLNK/KOMA BUT STILL LINGER AT KOFK...AND EXPECT AT LEAST IFR CIG/VIS TO CONTINUE AT KOFK FOR SEVERAL MORE HOURS...WITH ONLY A BRIEF RESPITE BEFORE FRONTAL PASSAGE BRINGS LOWERED CIGS AGAIN. PRECIP AT KOFK IS EXPECTED AFTER 06Z...WITH A MIX OF SN AND IP POSSIBLE BEFORE CHANGING TO SN. AT KOMA...MAY SEE SOME LATE AFTN/EVNG SHRA...THEN A LULL...BEFORE RAIN BEGINS AGAIN AFTER 09Z...POSSIBLY MIXING WITH FZRA OR SN. AT KLNK...ALSO MAY SEE AFTN/EVNG SHRA...THEN A LULL...BEFORE RAIN BEGINS AGAIN AFTER 09Z...POSSIBLY MIXING WITH FZRA OR IP. WINDS AT ALL SITES WILL SWITCH TO NWLY THIS EVNG AT AROUND 12-15 KT AND BECOMING GUSTY. EXPECT TSRA TO REMAIN FAR ENOUGH SE TO KEEP OUT OF ALL TAF SITES. $$ && .OAX WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY FROM 4 AM TO 5 PM CDT TUESDAY FOR NEZ011-012-015>018-030>034-042>045-050-051-065. IA...WINTER WEATHER ADVISORY FROM 4 AM TO 5 PM CDT TUESDAY FOR IAZ043. && $$ DEE/RC/MAYES
