Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 251551 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1051 AM CDT MON AUG 25 2014 .UPDATE...
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ISSUED AT 1031 AM CDT MON AUG 25 2014 MID MORNING REGIONAL RADAR MOSAIC INDICATES THAT A WEAKENING MCS CONTS TO TRACK ENE THROUGH CNTRL NEB AND WILL SOON MOV INTO EASTERN NEB. LATEST SHORT RANGE MODELS GUIDANCE INDICATES THAT THIS SYSTEM WILL CONT TO WEAKEN AS IT SHIFTS INTO THE AREA AS THE NOCTURNAL LOW-LEVEL JET WEAKENS AND BACKS WITH TIME. HAVE INCREASED THE POPS IN THE WRN CWA FOR THIS ACTIVITY AS IT MOVES IN...BUT WE SHOULD SEE A DECREASE IN COVERAGE AS WE GO THROUGH THE MORNING. SUBSIDENCE IN THE WEAK OF THE MCS...AS WELL AS LARGE-SCALE HEIGHT RISES THROUGH THE DAY TODAY MAKE CONVECTIVE REDEVELOPMENT UNCERTAIN FOR THE AFTERNOON TIME PERIOD. UPPER AIR ANALYSIS AND MID MORNING WATER VAPOR IMAGERY DO INDC A WEAK SHRTWV TROUGH OVER UT/WRN CO BUT THIS LIKELY WON`T MAKE IT TO OUR AREA UNTIL TONIGHT. IN ADDITION THE CLOUD DEBRIS FROM THE MORNING ACTIVITY WILL LIKELY LIMIT AFTN INSTABILITY. WITH THIS THINKING IN MIND WE HAVE REMOVED AFTERNOON POPS FROM THE FA AFTER CURRENT MCS DISSIPATES. WE HAVE ALSO TRIMMED HIGHS IN THE NRN CWA WHERE CLOUDS ARE EXPECTED TO PERSIST THE LONGEST. NO OTHER CHANGES PLANNED ATTM WITH CONVECTIVE CHANCES INCREASING DURING THE OVERNIGHT HOURS.
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&& .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 246 AM CDT MON AUG 25 2014 ...WET WEEK SETTING UP WITH POTENTIALLY LOCALLY HEAVY RAIN BUT OVERALL LOW SEVERE THREAT... THUNDERSTORM ACTIVITY CURRENTLY ACROSS THE MID MISSOURI RIVER VALLEY WILL BE EAST OF THE AREA BY 12Z. WILL HAVE TO WAIT FOR THE NEXT IMPULSE MOVING OUT OF NORTHEAST COLORADO TO ARRIVE LATER TODAY TO GENERATE ANY PRECIPITATION...SO MOST OF THE MORNING WILL LIKELY BE DRY WITH PRECIP CHANCES INCREASING THIS AFTERNOON... ESPECIALLY ACROSS NORTHEAST NEBRASKA. MEANWHILE...A FRONTAL BOUNDARY WILL REMAIN STALLED FROM NORTHEAST KANSAS THROUGH CENTRAL IOWA TODAY WITH NORTHEASTERLY WINDS PREVAILING. HIGH TEMPS WILL AGAIN RANGE FROM THE MID 70S NEAR THE NE/SD BORDER TO THE MID 90S NEAR THE KS/NE BORDER. NUMEROUS SHOWERS AND THUNDERSTORMS SHOULD DEVELOP TONIGHT AS ANOTHER IMPULSE FROM THE MEAN SOUTHWESTERN TROUGH EJECTS OFF THE FRONT RANGE. PW VALUES INCREASE TO 1.50 TO 1.75 INCHES... WHICH IS IN THE 90-97% CLIMATOLOGICAL PERCENTILE BASED ON NAEFS MODEL. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH AREAS ALONG/NORTH OF I80 EASILY PICKING UP ONE HALF TO ONE INCH OF RAINFALL TAPERING TO LOWER AMOUNTS FURTHER SOUTH AS YOU GET CLOSER TO THE STALLED SURFACE FRONT. WEAK IMPULSE SHOULD STILL BE MOVING THROUGH THE REGION TUESDAY MORNING WITH SHOWERS STILL LIKELY. PERSISTENT EASTERLY FLOW COMBINED WITH SUBSIDENCE BEHIND THE FIRST WAVE SHOULD ALLOW FOR LESS AREAL COVERAGE IN THE AFTERNOON AND SOME AREAS NORTH OF I80 COULD EVEN BE DRY ALTOGETHER. THIS WILL BE IN ADVANCE OF THE NEXT IMPULSE THAT MOVES OUT OF THE MEAN TROUGH TUESDAY NIGHT. MODELS SUGGEST THIS IMPULSE COULD BE STRONGER THAN THE FIRST ONE EXPECTED TONIGHT. PW VALUES REMAIN RATHER MOIST AT 1.75 TO 2 INCHES...AGAIN WELL WITHIN THE 90-97% NAEFS CLIMATOLOGICAL PERCENTILE. THIS WILL RESULT IN ANOTHER NIGHT OF LOCALLY HEAVY RAINFALL WITH 1 TO 2 INCHES OF POTENTIAL QPF OVER A LARGE PORTION OF THE FORECAST AREA. THE REGION IS ALSO WITHIN A SLIGHT RISK OF EXCESSIVE RAINFALL. HOWEVER...BELIEVE WE CAN HANDLE THE RAIN SINCE IT WILL BE SPREAD OUT OVER A COUPLE OF DAYS...THUS NO PLANS FOR ANY FLOOD HEADLINES AT THIS TIME. THE WET PATTERN CONTINUES INTO WEDNESDAY WITH NO MAJOR PATTERN CHANGE. SCATTERED TO NUMEROUS SHOWERS WILL LIKELY CONTINUE. OVERALL SEVERE THREAT APPEARS LOW WITH MAIN FOCUS ON HEAVY RAIN POTENTIAL. .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 246 AM CDT MON AUG 25 2014 PERSISTENT WET PATTERN WILL REMAIN WEDNESDAY NIGHT AND THURSDAY WITH HIGH PW VALUES REMAINING ACROSS THE REGION. SHOWERS/STORMS WILL REMAIN LIKELY DURING THIS PERIOD...WITH ANOTHER NIGHT OF POTENTIAL HIGH QPF WITH ANOTHER ONE HALF TO ONE AND ONE HALF INCHES OF RAIN EXPECTED THROUGH DAYBREAK THURSDAY. AGAIN THE AREA IS IN A DAY 3 SLIGHT RISK FOR EXCESSIVE HEAVY RAINFALL. BY THIS TIME...WILL HAVE TO MONITOR FOR POTENTIAL RIVER RISES AND ANY ASSOCIATED FLOODING THAT COULD RESULT. THE WET PATTERN CONTINUES INTO FRIDAY AND SATURDAY AS THE UPPER TROUGH SLOWLY MOVES ACROSS THE PLAINS. THE GFS MODEL HAS BEEN TOO FAST MOVING THIS TROUGH EAST THE LAST SEVERAL DAYS. SLOWER ECMWF SEEMS TO BE MORE LIKELY. && .AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 638 AM CDT MON AUG 25 2014 LIFT INCREASING ACROSS CENTRAL NEBRASKA THIS MORNING AND SHOULD SEE A CLUSTER OF SHRA/TSRA LIFT NORTHEAST INTO NORTHEAST NEBRASKA. AS THETA-E ADVECTION CONTINUES...SOME OF THE HI RESOLUTION FORECASTS DO HOLD THIS PRECIPITATION TOGETHER THROUGH THE AFTERNOON. FOR NOW HAVE VCSH/-SHRA AT KOFK AND COULD SEE VCSH AT LNK...BUT LEFT OUT OF KOMA FOR NOW. NEXT AREA OF LIFT INCREASES OVERNIGHT AND INCLUDE TEMPO TSRA AT KOFK/KOMA OVERNIGHT AND A PROB 30 AT KLNK. FOR NOW VFR CONDITIONS WILL PREVAIL WITH MVFR/IFR/LIFR POSSIBLE IN AREAS OF PRECIPITATION. WINDS WILL BE VARIABLE NEAR STORMS...HOWEVER THE PREVAILING WIND DIRECTION WILL BECOME FROM THE NORTHEAST AT 5 TO 10KTS. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ UPDATE... SHORT TERM...DEWALD LONG TERM...DEWALD AVIATION...ZAPOTOCNY

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