Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 292008 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 308 PM CDT FRI AUG 29 2014 .SHORT TERM...(TONIGHT THROUGH MONDAY) ISSUED AT 300 PM CDT FRI AUG 29 2014 OTHER THAN LINGERING CONVECTION THIS EVENING MAIN FOCUS IN SHORT TERM WILL BE THUNDERSTORM CHANCES/STRENGTH ON SUNDAY AS ACTIVE PATTERN TO PERSIST THROUGH PERIOD. AFTERNOON SATELLITE IMAGERY SHOWED UPPER TROUGH MOVING INTO EXTREME EASTERN NEBRASKA WITH PIVOT POINT NEARING MISSOURI RIVER AS OF 19Z. TROUGH SHOULD BE KICKED EWD FAIRLY QUICKLY THIS EVENING BY UPSTREAM WAVE FAST APPROACHING NW NEBR. BUT BESIDES CURRENT CONVECTION ONGOING TO ERN NEBR WAVE...MAY HAVE TO ACCOUNT FOR SOME UPSTREAM CONVECTION...WHICH HAD NOT YET DEVELOPED AS OF 19Z...WORKING TOWARD NWRN ZONES FOR A FEW HRS THIS EVENING AND SOME LAST MINUTE CHANGES PROBABLE. WITH MOISTURE PLENTY AND WAVE TAPPING SOME MOISTURE OFF OF GULF SYSTEM...SLOW MOVEMENT COULD AID IN A FEW LOCATIONS RECEIVING HEAVY RAIN. HOWEVER...GIVEN MODERATELY LIGHT DEEPER SHEAR VALUES PRESENT AND CLOUDS/EARLIER CONVECTIVE OVERTURNING KEEPING ML CAPE VALUES MODEST...SEVERE THREAT PROBABLY REMAINING ISOLD AT BEST. THAT SAID...PER SPC MD 1633 WITH LOW LEVEL CAPE AND VORTICITY PRESENT WITH UPPER TROUGH A BRIEF TOR NOT IMPOSSIBLE ...SPCLY IF CLEAR SLOT INTO SERN NEBR AT 19Z WOULD ALLOW IT TO FURTHER DESTABILIZE BEFORE BEING OVERRUN BY CLOUDS/LIGHT SHOWERS TO THE WEST. PLAN ON GENERALLY ENDING MOST POPS BY 06Z. LITTLE/NO CHANGES TO LOWS TONIGHT AND WITH RESIDUAL MOISTURE AND LIGHT WINDS LEFT IN LATE NIGHT FOG. SHORT WAVE RIDGING AHEAD OF NEXT TROUGH SHOULD BRING A DRY AND WARMER DAY ON SATURDAY AND AGAIN LITTLE/NO CHANGES TO TEMPS. LEFT IN SMALL LATE NIGHT POPS NWRN ZONES SAT NIGHT AS LOW LEVEL JET/WARM ADVECTION INCREASES AHEAD OF NEXT TROUGH. ALTHOUGH ELEVATED CONVECTION COULD PERSIST INTO SUN AFTN AIDED BY LOW LEVEL JET...PER NAM/GFS...12Z ECMWF GENERALLY KEPT AREA DRY UNTIL 00Z MONDAY WHEN STRONG UPPER JET PUNCHES INTO REGION ON SOUTH SIDE OF THIS NEXT UPPER TROUGH. DUE TO UNCERTAINTY IN AMOUNT OF ELEVATED CONVECTION PRECEDING MAIN LATE AFTN/EVENING DEVELOPMENT LEFT IN MORNING POPS NW 2/3RDS AND DID NOT BREAK UP THE AFTN PERIOD TO ACCOUNT FOR POSSIBLE HIGHER CHANCES LATE IN THE AFTN. DID BOOST MAX TEMPS A FEW DEGREES SOUTH ON SUNDAY AS THAT AREA DID SEEM THE LESS SUSCEPTIBLE TO IMPACT OF MORNING WARM ADVECTION CLOUDS PSBL PRECIP. STRONG/SEVERE STORM CHANCES APPEAR HIGHER THAN PAST SEVERAL DAYS AS 0-6KM SHEAR IS STRONGER AND MAX TEMPS NEARING 90 SHOULD INCREASE MLCAPE VALUES. ALTHOUGH HEAVY RAIN WILL LIKELY OCCUR WITH THE ACTIVITY AS WELL...VERY HARD TO PIN DOWN WHERE AXIS OF HEAVIEST WILL OCCUR AS A CASE COULD BE MADE FOR IT SETTING UP JUST ABOUT ANYWHERE IN OR EVEN POSSIBLY JUST OUTSIDE THE FA. ALTHOUGH LABOR DAY WILL BE KEPT DRY FOR NOW...OUTSIDE A LINGERING MORNING MENTION FAR SE...FAST MOVING FLOW WILL ALLOW APPROACH OF NEXT WAVE BY AFTN IN NW NEBR. ALSO FRONT SHOVED SOUTH WITH SUNDAY/S WAVE COULD STALL OUT MONDAY AFTN BEFORE ATTEMPTING TO LIFT NORTH MONDAY NIGHT. BOTH OF THESE ITEMS COULD ALLOW SOME ADDITIONAL INCLUSION IN POPS IN LATTER FORECASTS FOR LABOR DAY. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 300 PM CDT FRI AUG 29 2014 BECAUSE OF AFOREMENTIONED SETUP DESCRIBED ABOVE...SMALL POPS WERE INCLUDED ALL ZONES MON NIGHT AND ACROSS THE SE ON TUE. OTHERWISE BUILDING UPPER HEIGHTS WITH JET SHIFTING FARTHER N PER 12Z ECMWF/GFS LENT ITSELF TO A DRY FORECAST WED ALONG WITH WARMING TEMPERATURES. ALTHOUGH PRIOR FORECAST/00Z MODELS SUGGESTED A CONTINUATION OF THE DRY FORECAST THU...WHICH WAS MAINTAINED...LATEST GFS/ECMWF ALLOWED A FRONT TO WORK INTO THE NRN ZONES AT LEAST ON THURSDAY AS AN UPPER WAVE DROPPED SE THROUGH CANADA. THE NEW DAY 7 WILL INCLUDE PRECIP CHANCES WITH THIS SCENARIO AND IF TRENDS WOULD PERSIST...POPS MAY EVENTUALLY BE INSERTED TO THU PERIOD AS WELL...SPCLY N. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1250 PM CDT FRI AUG 29 2014 SCATTERED CONVECTION IS LIKELY ACROSS EASTERN NEBRASKA THROUGH 00Z AS VIGOROUS UPPER WAVE OVER THE CENTRAL PLAINS MOVES EAST. MVFR CONDITIONS EXPECTED DURING THIS TIME FOLLOWED BY A PERIOD OF VFR THROUGH ABOUT 08Z. MVFR TO IFR CONDITIONS IN FOG AND CIGS EXPECTED AFTER 08Z THRU ABOUT 14Z WITH LIGHT WINDS AND ABUNDANT LOW LEVEL MOISTURE IN PLACE. VFR CONDITIONS THEN DEVELOPING 14Z-18Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...CHERMOK LONG TERM...CHERMOK AVIATION...FOBERT

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