Issued by NWS North Platte, NE
000 FXUS63 KLBF 230817 AAA AFDLBF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 317 AM CDT THU OCT 23 2008 .DISCUSSION... UPPER LOW HAS WOBBLED BUT MOVED VERY LITTLE THE PAST 6-8 HOURS OVER N.CENTRAL KS/SC NEB. DRY SLOT WITH WRAPPING INTO THIS LOW AND BACK INTO WESTERN NEBRASKA. SFC LOW DURING THIS SAME TIME FRAME HAS RETROGRADED FROM NEAR FNB AT 00Z TO NEAR CNK OT 08Z. LARGE AMOUNT OF DRY AIR ACROSS WESTERN NEB ADVECTED IN ON NW WINDS PER UNR RAOB HELPED TO KEEP PCPN AT BAY ACROSS AREAS WEST OF HIGHWAY 83 WITH VIRGA/LIGHT RAINFALL THE MAIN THREAT...THOUGH WAS PROBABLY SNOWING REALLY GOOD UP AT 8KFT. DRY SLOT WAS FEEDING INSTABIITY INTO BACK NW SIDE OF LOW IN REGION OF TROWAL AND THIS COMINATION HAS LED TO SLANTWISE CONVECTION FINALLY STRONG ENOUGH TO SATURATE FROM TOP DOWN AND COOL PBL WET BULB ENOUGH FOR SNOW PRODUCTION. LARGE FLAKES AT KLBF GOOD INDICATION THAT DENDRITIC LAYER WAS BEING FULLY UTILIZED. WARM/WET GROUND WAS HAMPERING ACCUMULATIONS HOWEVER FROM FEW PHONE CALLS AROUND 2+ INCHES HAVE FALLEN FROM PORTIONS OF CUSTER TO INTO LINCOLN COUNTY AND BANDED PCPN CONTINUES TO BE PRESENT PER LATEST 88D LOOP. NAM/GFS SHOWING THIS WELL IN X-SECTIONS WITH NEG EPV LAYER AND EVEN BENT BACK THETA-E LINES OVER REGION WHERE SNOWFALL IS OCCURRING ALONG WITH ISOLATED LIGHTNING STRIKES. EXPECT ISOLATED AREAS COULD BE GETTING 1"+ PER HOUR IN SOME OF THESE PERSISTANT BANDS. BOTH SHORT TERM MODELS SHOW THIS WELL IN THE 300-305K THETA LAYERS AS WELL...WITH STRONG UPGLIDE DECREASING AFTER 12Z AS CYCLONE GETS FULLY WRAPPED UP AND BEGINS TO FILL AND SLOWLY WOBBLE SOUTHEAST. EXPECT ONLY SMALL ACCUMULATIONS THROUGH MID MORNING ONWARD BUT COULD SEE SOME BETTER SNOWFALL RATES UNTIL CSI IS OVERCOME. WIND STILL SOMEWHAT OF A PROBLEM WITH OGA STILL GUSTING NEAR 50MPH. AS SUCH WILL LEAVE WARNING IN PLACE FROM WESTERN ZONES UP TO AND ALONG HIGHWAY 2. NORTH OF HERE CONDITIONS IMPROVING SO PLAN TO DROP HEADLINES AS DO NOT EXPECT MUCH ADDITIONAL ACCUMS AND WINDS SHOULD BE DROPPING. THINGS SHOULD QUICKLY TAPER OFF THROUGH AFTERNOON AND EVENING AND SHOULD BE DRY THROUGH REMAINDER OF FCST. BIGGEST CHANGE WILL BE TO COOL OFF SUN/MON WITH STRONG HIGH LAT SYSTEM DROPPING INTO GREAT LAKES AND CARVING OUT DEEP E.CONUS TROF...WHICH WILL PUSH BACK DOOR FRONT THROUGH SAT NIGHT. .AVIATION... THE UPPER LEVEL LOW PRESSURE CENTER...RESPONSIBLE FOR THE PRECIPITATION OVER THE PAST 24 HOURS...WILL MOVE LITTLE OVER THE NEXT 12 TO 24 HOURS. THE RESULT WILL BE PERSISTENT MVFR CEILINGS OVER THE NEXT 24 HORUS. THROUGH 00Z THIS EVENING...MVFR CEILINGS ARE EXPECTED WITH CEILINGS RANGING FROM 2000 TO 4000 FEET. GIVEN THE ABUNDANCE OF LOW LEVEL MOISTURE...CEILINGS WILL DROP SOMEWHAT OVERNIGHT AND MAY REACH BLO 1000 FEET AT THE KLBF TERMINAL BY 12Z FRIDAY. GIVEN SOME UNCERTAINTIES BETWEEN FORECAST MODELS...WILL AVOID MENTION OF IFR CEILINGS ATTM. VISIBILITIES WILL IMPROVE BY 15Z THIS MORNING AS SNOWFALL INTENSITIES DECREASE. FROM 12Z TO 15Z...VISIBILITIES MAY BE REDUCED TO UNDER AROUND A MILE WITH SNOW AND BLOWING SNOW. && .LBF WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR NEZ025>028-036>038-057>059-069>071. && $$ 13/CLB
