Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 150543 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1143 PM CST SUN DEC 14 2014 .SHORT TERM...(TONIGHT THROUGH WEDNESDAY) ISSUED AT 320 PM CST SUN DEC 14 2014 SHORT TERM FORECAST CONCERNS CONTINUE TO BE PRECIPITATION/TYPE...CHANGEOVER TO SNOW/AMOUNTS AND WIND WITH VIGOROUS STORM SYSTEM TONIGHT THROUGH MONDAY EVENING AND HEADLINES. IT WAS A VERY MILD SATURDAY WITH RECORD WARM MINIMUMS SET AT OFK/OMA/LNK. WE WE STARTED OUT MILD AGAIN WITH LOWS AROUND 50...DRIZZLY AND FOGGY TOO. THE 12Z OAX SOUNDING HAD INCREASED TO .71 PWAT...WITH MOST OF THE MOISTURE IN THE LOWEST 5K FEET. THE H3 100KT JET WAS DIVING SOUTHEAST ACROSS ARIZONA. MEANWHILE...THE H5 TROF EXTENDED FROM IDAHO SOUTHEAST TO NEW MEXICO WITH THE MID LEVEL RIDGE SHIFTING EASTWARD TO THE GREAT LAKES AND TENNESSEE VALLEY. THE LARGEST HEIGHT FALLS OF 130M WERE NOTED AT KABQ. THE SYSTEM WAS NEGATIVELY TILTED WITH H5 LOW PRESSURE OVER NORTHERN NEW MEXICO AND A SECOND AREA OF LOW PRESSURE BACK TOWARD SOUTHERN IDAHO. WATER VAPOR SATELLITE IMAGERY SHOWED MOISTURE STREAMING NORTHWARD. A LARGE SWATH OF +10 DEG H85 DEWPOINTS STRETCHED FROM TEXAS ACROSS KANSAS WITH +8 DEG DEWPOINTS AT KOMA. PER VISIBLE SATELLITE AND RADAR AT 16Z...WE WERE STARTING TO SEE A LITTLE BUMPIER CLOUDS NEAR HEBRON IN SOUTH CENTRAL AS ELEVATED INSTABILITY WAS INCREASING IN THAT AREA. THERE WERE A FEW RANDOM STRIKES NEAR HAYS KS...HOWEVER THE CONVECTION WAS MORE ORGANIZED IN A BAND FROM EASTERN COLORADO...TO GOODLAND AND DODGE CITY THROUGH OKLAHOMA. BY 21Z...THE ORGANIZED CONVECTION WAS IN BANDS. A WEST TO EAST BAND NEAR NORTH PLATTE...AND ANOTHER BAND FROM NORTH OF GOODLAND ACROSS NORTHERN KANSAS INTO EAST CENTRAL KANSAS. THROUGH 00Z...THE 998MB SURFACE LOW OVER SOUTHEAST COLORADO TRACKS TO SOUTHWEST KANSAS...HEADS TOWARD NORTHEAST KS BY 12Z MONDAY AND TO SOUTHEAST IOWA BY 00Z MONDAY EVENING. THE H5/H7/H85 TRACKS ARE SIMILAR. THE H85 PATTERN IS A LITTLE MORE COMPLEX...AS BOTH THE GFS/NAM HAVE A DOUBLE H85 CIRCULATION...ONE OVER NORTHEAST KS AND A SECONDARY CIRCULATION FARTHER NORTH TOWARD SUX CITY. DEEP MOISTURE WILL STREAM NORTHWARD...SHIFTING INTO IOWA TONIGHT...WITH THE MOISTURE WRAPPING AROUND THE SYSTEM. TWO AREAS OF PRECIPITATION SHOULD EXPAND...THE FIRST IS ASSOCIATED WITH THE INCREASING UPPER LEVEL DIVERGENCE/OMEGA/DPVA AND STEEPENING LAPSE RATES ON THE NORTHEAST SIDE OF THE LOW AND THE SECOND IS WHERE THERE IS ASSOCIATED WITH THE AFOREMENTIONED...BUT ALSO ENHANCED CONVERGENCE ALONG THE FRONT IN NORTHEAST NEBRASKA. THE LIFT INCREASES ACROSS THE AREA TODAY...IS MAXIMIZED AT 06Z TONIGHT THEN LIFTS NORTH AND SHIFTS EAST. THE NAM/GFS BOTH HAVE CONVECTIVE PRECIP AND ELEVATED INSTABILITY THESE AREAS...SO WILL CONTINUE TO MENTION THUNDER AS THESE FEATURES TRAVERSE THE FORECAST AREA. CRITICAL THICKNESS VALUES/TEMPERATURES REMAIN FAVORABLE FOR LIQUID PRECIPITATION THROUGH 09Z...WITH RAIN CHANGING TO FREEZING RAIN/ SNOW 10-15Z FOR KNOX/CEDAR/ANTELOPE COUNTIES...THE CHANGEOVER MAKES IT TO A WAYNE/DAVID CITY LINE 18-21Z AND LINCOLN/FREMONT BY 00Z...OMAHA EARLY IN THE EVENING AND NEB CITY TO HARLAN BY 03Z AND THE REST OF SOUTHWEST IOWA/SOUTHEAST NEB THROUGH 06Z. MOST LOCATIONS SHOULD SEE A THIRD OF AN INCH OF RAIN WITH POCKETS OF HIGHER .5 TO 1 INCH WATER EQUIVALENTS. THE MOST COMPLEX PART OF THE FORECAST ARE THE TEMPERATURES AND MIXED PRECIP/CHANGEOVER. THE NAM/GFS AT 17Z HAD A GOOD HANDLE ON THE GRADIENT IN TEMPERATURES...WITH UPPER 30S AT AINSWORTH...50 AT ONL...AND 55 AT YANKTON...HOWEVER FOR 18Z...THE COLDER AIR WAS GETTING INTO ONL QUICKER THAN THE MODELS HAD. THE GFS WAS BETTER WITH THE DEWPOINT GRADIENT BETWEEN AINSWORTH AND ONL. FOR NOW HAVE THE HIGHER SNOWFALL AMOUNTS IN THE NORTHWEST PART OF THE FORECAST AREA. WHERE THE WINTER WEATHER ADVISORY IS...MOST SPOTS HAVE SOME ICING POSSIBLE...THEN 1-3 INCHES OF SNOW AND VERY STRONG WINDS WITH BLOWING SNOW. DID ADD KNOX COUNTY TO A WINTER STORM WARNING AS DO HAVE A RANGE OF SNOW WITH 6 OR MORE INCHES POSSIBLE IN THE NORTHWEST PART OF THE COUNTY. AS DISCUSSED...THE RAIN TO SNOW CHANGEOVER WILL AFFECT THE EVENTUAL SNOW AMOUNTS...IF THE SNOW CHANGES OVER QUICKER...THESE AMOUNTS MAY NEED TO BE RAISED. STRONG WINDS...MOS GUIDANCE HAS THE FORECAST AREA HITTING WIND ADVISORY CRITERIA...AS 40 TO 45KT WINDS ALOFT MIX DOWN. DO HAVE NORTHWEST WINDS INCREASING BEHIND THE FRONT 22-30KTS SUSTAINED AFTER 18Z THROUGH MONDAY EVENING. DUE TO THE STRONG WINDS AND LINGERING BLOWING SNOW...EXTENDED THE ADVISORY INTO THE EARLY EVENING. THE STORM SYSTEM PULLS AWAY FOR TUESDAY WITH COLD HIGH PRESSURE OVER THE AREA AND HIGHS IN THE 20S/30S TUESDAY AND WEDNESDAY .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 320 PM CST SUN DEC 14 2014 WEDNESDAY NIGHT THROUGH FRIDAY NIGHT...SOME SHORTWAVE TROF ENERGY IS PUSHING INTO THE PLAINS THAT WILL BRING THE CHANCE FOR LIGHT SNOW TO PARTS OF THE FORECAST AREA BEFORE THE WAVE MOVES EAST INTO THE OHIO/TENNESSEE VALLEY. THERE ARE STILL SOME STRENGTH...TIMING AND LATITUDE DIFFERENCES...BUT COULD GENERATE SOME LIGHT DUSTING TO 1 INCH AMOUNTS. && .AVIATION...
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(06Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1138 PM CST SUN DEC 14 2014 COLD FRONT HAD SLIPPED SOUTH OF KOFK AS OF 06Z. IFR CIGS WITH OCCASIONAL RAIN WILL OCCUR THERE THROUGH THE NIGHT BEFORE COLDEST AIR FILTERS IN AND BRINGS A PERIOD OF FREEZING RAIN OR SLEET FROM 12Z THROUGH 15Z...THEN SNOW AFTER 15Z. OCCASIONAL LIFR OR VLIFR CONDITIONS ARE LIKELY INTO THE MID AFTERNOON IN SNOW...WITH NORTH WINDS GUSTING OVER 35KT. FARTHER SOUTHEAST...KOMA AND KLNK WILL SEE MVFR CIGS/VSBYS IN RAIN THROUGH THE NIGHT. COLD FRONT WILL REACH THOSE SITES BETWEEN 12Z AND 15Z...CHANGING WINDS TO THE NORTH AND LOWERING CIGS TO BELOW FL010. A GRADUAL CHANGE TO SNOW IS EXPECTED AT KLNK BY 22Z AND KOMA BY 00Z. SNOW SHOULD BE WINDING DOWN AFTER 00Z...BUT NORTH WINDS INCREASING INTO THE 25 TO 35 KT RANGE CAN BE EXPECTED. IFR/MVFR CIGS WILL LINGER AFTER SNOW ENDS.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY FROM 6 AM TO 9 PM CST MONDAY FOR NEZ012- 017-018-031-032-042. WINTER WEATHER ADVISORY FROM 4 AM TO 9 PM CST MONDAY FOR NEZ016- 030. WINTER STORM WARNING FROM 4 AM TO 9 PM CST MONDAY FOR NEZ011. IA...NONE. && $$ SHORT TERM...ZAPOTOCNY LONG TERM...ZAPOTOCNY AVIATION...DERGAN

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