000 FXUS63 KLBF 110530 AAC AFDLBF AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NORTH PLATTE NE 1130 PM CST TUE DEC 10 2013 .SYNOPSIS... ISSUED AT 305 PM CST TUE DEC 10 2013 H5 ANALYSIS THIS MORNING HAS BROAD NORTHWESTERLY FLOW ACROSS THE WESTERN HALF OF THE CONUS WITH DEEP LOW PRESSURE OVER SRN HUDSON BAY. AT THE SURFACE...A COLD FRONT EXTENDED FROM NERN WYOMING INTO NERN SD. FURTHER SOUTH ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...WESTERLY FLOW HAS DEVELOPED THIS AFTERNOON WITH TEMPERATURES REACHING THE 20S AND LOWER 30S. && .UPDATE... ISSUED AT 614 PM CST TUE DEC 10 2013 THE ECM...RAP...GEM REG AND HRRR MODELS SHOW WIND CHILL ADVISORY CONDITIONS BY MORNING ACROSS THE NORTHEAST FROM AINWSORTH AND ONEILL NORTH. A NEW FORECAST IS OUT FOR THESE CONDITIONS. OTHERWISE THE REST OF THE FORECAST IS ON TRACK WITH THE LEADING EDGE OF THE ARCTIC AIR ENTERING SHERIDAN COUNTY AND SETTING OFF SNOW SHOWERS. LOW LEVEL LAPSE RATES ARE VERY STEEP WITH ECHO TOPS LESS THAN 10KFT. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 305 PM CST TUE DEC 10 2013 AN ARCTIC COLD FRONT WILL MOVE SOUTHEAST ACROSS THE AREA TONIGHT...WITH A FEW SNOW SHOWERS POSSIBLE ACROSS NORTHERN NEBRASKA BEHIND THE FRONT. FLURRIES ARE POSSIBLE FARTHER SOUTH AS WELL...WITH A PERIOD OF WEAK LIFT THROUGH A SATURATED DENDRITIC LAYER BEHIND THE FRONT. OTHERWISE...WINDS DIMINISH AS HIGH PRESSURE SETTLES INTO NORTHERN NEBRASKA LATE TONIGHT. THIS WILL ALLOW FOR LOWS TO DROP TO NEAR ZERO OR JUST BELOW AS SKIES CLEAR LATE. FARTHER SOUTH WINDS REMAIN UP THROUGH THE NIGHT...AND THIS WILL HELP KEEP LOWS SOMEWHAT WARMER. HIGH PRESSURE WILL QUICKLY MOVE SOUTHEAST OF THE AREA WEDNESDAY...WITH WARMING SOUTHWEST WINDS DEVELOPING BY WEDNESDAY AFTERNOON. HAVE PUSHED HIGHS UP INTO THE LOWER 30S ACROSS SOUTHWEST NEBRASKA...BUT ONLY NEAR 20 DEGREES ACROSS EASTERN PORTIONS OF NORTH CENTRAL NEBRASKA WHERE THE ARCTIC AIR WILL BE DEEPER. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 305 PM CST TUE DEC 10 2013 IN THE MID RANGE...TEMPERATURES ARE THE MAIN FORECAST CHALLENGE. FOR WEDNESDAY NIGHT...LOOK FOR WINDS TO DECREASE BY LATE EVENING AS A WARM FRONT TRACKS EAST OF THE AREA. CLEAR SKIES AND LIGHT WINDS WILL ALLOW TEMPS TO DIP INTO THE SINGLE DIGITS ACROSS THE FORECAST AREA. INHERITED FORECAST HAD ALOT OF TEENS FOR LOWS WEDS NIGHT AND SCALED THESE BACK TOWARD THE NEW GUIDANCE...WHICH TRENDED MUCH LOWER AS WELL. ON THURSDAY...WARMER PACIFIC AIR WILL PUSH INTO THE CENTRAL PLAINS WITH H85 TEMPS REACHING THE MIDDLE SINGLE DIGITS CELSIUS ABOVE ZERO THURSDAY AFTERNOON. NORMALLY WITH GOOD MIXING...HIGHS WOULD REACH THE UPPER 40S TO LOWER 50S. HOWEVER...WINDS ARE EXPECTED TO BE FAIRLY LIGHT THURSDAY...A BY PRODUCT OF SNOW COVER AND ITS IMPACT ON MIXING. BUFKIT SOUNDINGS FOR BOTH LBF AND VTN ARE NOT INDICATIVE OF MIXING EITHER. GUIDANCE HIGHS THURSDAY FOR VALENTINE WERE IN THE MID 40S WITH THIS MORNINGS FCST. THIS SEEMS WAY TOO HIGH WITH 6+ INCHES OF SNOW EXPECTED TO BE ON THE GROUND ACROSS NORTH CENTRAL NEBRASKA. HAVE OPTED FOR HIGH IN THE LOWER 40S SOUTHWEST TO LOWER 30S IN THE NORTHEAST AND PORTIONS OF THE NORTH CENTRAL FORECAST AREA. LOWS THURSDAY NIGHT WILL BE SLIGHTLY HIGHER THAN WEDNESDAY NIGHTS MIN TEMPS DUE TO INCREASED HIGH LEVEL CLOUDINESS...AND THE DEVELOPMENT OF LIGHT WINDS IN ADVANCE OF THE NEXT ARCTIC COLD FRONT WHICH WILL ARRIVE SOMETIME FRIDAY MORNING OR AFTERNOON. I DID GO AHEAD AND TREND DOWN HIGHS FRIDAY ACROSS THE NORTHERN CWA BASED ON A SLIGHTLY FASTER FRONTAL TIMING IE. GFS SOLUTION...WHICH HAS BEEN MORE CONSISTENT. HIGHS FRIDAY WILL RANGE FROM THE MID 20S IN THE NORTHEAST...TO AROUND 40 IN THE SOUTHWEST. FRIDAY NIGHT THROUGH TUESDAY...BROAD NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE CENTRAL AND NORTHERN PLAINS FOR THE EXTENDED PERIOD. WITH THE NORTHWESTERLY FLOW IN PLACE ARCTIC COLD AIR WILL BACK INTO THE FORECAST AREA SATURDAY...RETREATING EASTWARD LATE SUNDAY OR MONDAY. ATTM...THE GFS AND ECMWF SOLUTIONS ARE AT ODDS WITH HOW FAST THE FRONT PUSHES EAST OUT OF THE AREA WITH THE GFS BEING SLOWER. ON MONDAY INTO TUESDAY...THE GFS ADVERTISES A NICE WARMUP WHILE THE ECMWF USHERS IN ANOTHER SHOT OF ARCTIC AIR. FOR NOW...WILL COMPROMISE BETWEEN SOLUTIONS AND LEAVE THE FORECAST DRY AS THE NORTHWESTERLY FLOW FAVORS IT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1129 PM CST TUE DEC 10 2013 MVFR CIGS BETWEEN KVTN AND KTIF WILL DROP SOUTH THROUGH KLBF OVERNIGHT. THE MODELS THEN SUGGEST THIS MOISTURE WILL BECOME TRAPPED AND PRODUCE IFR/LIFR CIGS TOWARD MORNING BUT THIS IS UNCERTAIN GIVEN THE VERTICAL MIXING THAT COULD DEVELOP AFTER SUNRISE. THE FCST FOLLOWS THE MODEL SOLN AT KLBF BUT KEEPS KVTN IN VFR DURING THE MORNING. IF THE MVFR/IFR CIGS DEVELOP AT KLBF AFTER NEAR OR AFTER SUNRISE THEN THEY WOULD LIKELY GET LIFTED EAST THROUGH KANW/KONL/KBBW DURING THE LATE MORNING AND AFTN AS A DEVELOPING WARM FRONT. && .LBF WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL 11 AM CST WEDNESDAY FOR NEZ006>010. && $$ UPDATE...CDC SYNOPSIS...CLB SHORT TERM...TAYLOR LONG TERM...CLB AVIATION...CDC