Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 302008 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 308 PM CDT SAT AUG 30 2014 .SHORT TERM...(TONIGHT THROUGH TUESDAY) ISSUED AT 300 PM CDT SAT AUG 30 2014 PRIMARY FOCUS FOR SHORT TERM REMAINS CONVECTIVE DEVELOPMENT ON SUNDAY AS MODELS CONTINUE TO INDICATE THE SEVERE WEATHER AND LOCALLY HEAVY RAIN THREAT PERSISTS. BROAD UPPER TROUGH WAS CROSSING THE ROCKIES TODAY PER LATEST WATER VAPOR IMAGERY WITH 12Z UA INDICATING LARGE AREA OF 50M HGT FALLS AT H5 FM OR/WA INTO MT. IN RESPONSE TO THE TROUGH/S APPROACH ...LOW LEVEL JET SHOULD INCREASE TONIGHT AND RESULTANT ISENTROPIC UPGLIDE COULD KICK OFF MAINLY ISOLD/HIGH BASED TSTMS LATE. MODEL TREND...SPCLY ECMWF...HAS BEEN TO EITHER DELAY SLIGHTLY OR MOSTLY IGNORE. BUT SOME SMALL POPS STILL SEEMED WARRANTED...BUT THEY WERE DELAYED JUST A BIT AND TRIMMED BACK A LITTLE SUNDAY MORNING. LITTLE CHANGES TO LOW TEMPERATURES TNGT. FALLING HEIGHTS AND SOME INCREASE IN MOISTURE SHOULD ERODE CAP SUNDAY AFTN...THINKING 21Z ISH...ALTHOUGH SLIGHT DIFFERENCES EXISTED ON WHERE MAIN INITIATION WOULD TAKE PLACE. EITHER NERN NEBR/NW IA PER NAM OR ECNTRL NEB/SW IA PER ECMWF. GFS WAS MORE OF A COMPROMISE. HOWEVER...JET AND FALLING HGTS COULD INCREASE COVERAGE BEHIND MAIN INITIATION AREA BY 00Z. ALTHOUGH MOST AREAS WILL HAVE HIGH LIKELY OR CATEGORICAL POPS BY EVENING...WHERE INITIAL DEVELOPMENT OCCURS COULD ACT AS FOCUS ON WHERE HEAVIEST PRECIP EVENTUALLY OCCURS. FOR THIS REASON NO FLASH FLOOD WATCH WILL BE ISSUED JUST YET...BUT HEAVY RAIN MENTION WILL BE CARRIED MUCH OF THE CENTRAL/ERN ZONES IN THE EVENING/EARLY OVERNIGHT HRS AS PRECIPITABLE WATER VALUES INCREASE TO OVER 2 INCHES ALONG FRONT PER NAM...WITH A LITTLE LESS THAN THAT FROM GFS. WITH 0-6KM SHEAR VALUES INCREASING TO 40 KTS+ MOST AREAS...SEVERE THREAT ALSO PERSISTS WITH HP SUPERCELLS A DECENT BET PER SWODY2. WITH LOW LEVEL JET REMAINING SWRLY SERN ZONES THROUGH 12Z MONDAY SOME PRECIP COULD LINGER INTO MONDAY MORNING...BUT WOULD SUSPECT EVENTUAL COLD POOL COULD FORCE BULK OF MCS E OF FA BY DAYBREAK. WITH TROUGHY NATURE TO UPPER FLOW ON LABOR DAY/MONDAY NIGHT...NEXT WAVE QUICKLY APPROACHES AND COULD ALREADY GENERATE AFTN SHOWERS/TSTMS INTO WRN ZONES AT LEAST. IF TRENDS WOULD PERSIST COULD FORESEE NEED TO INCLUDE PCPN IN LATER FORECASTS LABOR DAY AFTN BUT FOR NOW LEFT IT DRY. WITH LOSS OF HEATING AND A LOT OF THE MOISTURE CLEARED OUT BY SUN EVENING/S MCS...ACTIVITY COMING ACROSS THE FA WITH THE WAVE MON NGT SHOULD BE WEAKENING WITH COVERAGE NOT ESPECIALLY HIGH. THUS ONLY SLGT CHC/LOW END CHANCE POPS WERE MAINTAINED. TUE APPEARS DRY FOR NOW. COOLER MAX TEMPS FOR LABOR DAY/TUESDAY LOOKED GOOD WITH NO SIG CHANGES OR VARIANCE FROM GUIDANCE. .LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY) ISSUED AT 300 PM CDT SAT AUG 30 2014 WEDNESDAY/THURSDAY PERIODS WERE KEPT DRY...SUPPORTED BY 12Z GFS AND FOR CONTINUITY PURPOSES. A WARMING TREND SHOULD COMMENCE. IT WAS NOTED HOWEVER THAT ECMWF WAS QUICKER IN DRIVING A FRONT INTO FA THURSDAY AS WAVE TRACKS ACROSS SRN CANADA...ALTHOUGH NO PRECIP WAS GENERATED UNTIL THURSDAY NIGHT. WHICH A CASE COULD BE MADE WITH EARLIER DAY TIMING OF FRONT AND HIGH UPPER HGTS INITIALLY. TSTM CHANCES THEN WERE MAINTAINED FRIDAY AND ADDED TO THE NEW DAY 7 AS FRONT LINGERS IN AREA AND/OR ADDITIONAL UPPER WAVES TRACK ACROSS PLAINS. WITH THE INCREASED SHOWER/TSTM THREAT...AND ATTENDANT CLOUDS...FRIDAY AND SATURDAY SHOULD COOL AND A GENERAL MEX/ECE BLEND WAS MAINTAINED. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 113 PM CDT SAT AUG 30 2014 STRATUS LAYER FINALLY BREAKING UP AT KOMA AT START OF FORECAST PERIOD. VFR CONDITIONS EXPECTED AT ALL THREE SITES THROUGH THE REMAINDER OF THE FORECAST IN ADVANCE OF APPROACHING COLD FRONT. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...CHERMOK LONG TERM...CHERMOK AVIATION...FOBERT

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