000 FXUS65 KBYZ 100340 AFDBYZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BILLINGS MT 840 PM MST THU FEB 9 2012 .SHORT TERM...VALID FOR FRI AND SAT... UPDATE TO ZFP AND WRKAFP. COLD FRONT HAS BEEN ADVANCING STEADILY WESTWARD THROUGH THE FORECAST AREA THIS EVENING AS SHOWN BY PRESSURE RISES AND FALLING TEMPERATURES. RADAR HAS BEGUN TO FILL IN OVER THE CENTRAL ZONES ALONG THE ADVANCING COLD FRONT. LIGHT SNOW HAS BEEN OCCURRING OVER KBHK THROUGH THE EVENING UNDER A STRATUS DECK BEHIND THE FRONT. THE SLIGHT CHANCE OF SNOW THROUGH 06Z LOOKED GOOD OVER EASTERN AREAS. HAVE SPREAD THE SLIGHT CHANCE WEST AND NW TO ENCOMPASS AREAS WHERE THE RADAR HAS BEEN FILLING IN. MODELS ALL HAD THE FRONT CONTINUING TO PUSH W OVERNIGHT. THE FRONT WILL TAP INTO PACIFIC MOISTURE SPILLING INTO THE AREA OVER A RIDGE OVER THE PACIFIC NW. AS A RESULT...CHANCES OF SNOW WILL INCREASE OVERNIGHT AND THE GOING FORECAST HAD THIS COVERED WELL. LOWERED TEMPERATURES A FEW DEGREES OVERNIGHT DUE TO THE STRONG SURGE OF COLD AIR MOVING W INTO THE AREA AT 850 MB. ISENTROPIC LIFT WILL INCREASE OVER THE FRONTAL BOUNDARY ON FRI. THIS LIFT WILL COMBINE WITH LIFT FROM A SHORTWAVE ROTATING SW FROM CANADA TO BRING SNOW TO CENTRAL AND WESTERN PORTIONS OF THE AREA. NO CHANGES NEEDED TO REMAINDER OF FORECAST. ARTHUR .LONG TERM...VALID FOR SUN...MON...TUE...WED...THU... MADE MINIMAL CHANGES TO THE EXTENDED FORECAST PERIOD...WITH MODELS IN PRETTY GOOD AGREEMENT THROUGH MONDAY. MODEL AGREEMENT IS NOT AS GOOD FOR LATTER PORTION OF THE EXTENDED PERIOD...BUT SEEM TO BE COMING INTO BETTER AGREEMENT. IT LOOKS LIKE WE SHOULD HAVE A PERIOD OF CLEARING SUNDAY AND MONDAY BEHIND EARLY WEEKEND SYSTEM. PRECIP MAY LINGER A BIT SUNDAY...BUT NOTHING INDICATIVE OF THIS OTHER THAN THE LENGTH OF TIME THE PREVIOUS SYSTEM KEPT OVERRUNNING ACROSS THE REGION. HAVE INTRODUCED SOME FLURRIES ACROSS THE WEST TO ACCOUNT FOR SIMILARITY TO MOST RECENT SYSTEM. ALSO COOLED TEMPS OFF A COUPLE OF DEGREES FOR SUNDAY...AS COLD AIR SEEMS TO LINGER MOST OF THE DAY. MODELS DIFFER SIGNIFICANTLY ON TIMING OF SEVERAL WAVES MOVING THROUGH THE REGION TUESDAY THROUGH THE END OF THE PERIOD. HAVE RAISED POPS SLIGHTLY AS THINK THE SITUATION DESERVES BETTER THAN CLIMO TYPE POPS. THE MODELS INDICATE SOMEWHAT ACTIVE PERIOD...AND JUST SEEM TO BE HAVING ISSUE WITH TIMING. AS FOR TEMPS...HAVE KEPT TEMPS AROUND CLIMO AT THIS TIME...EVEN THOUGH GUIDANCE IS INDICATING WARMER TEMPS FOR MONDAY AND TUESDAY. MIX DOWNS SEEM TO FAVOR COOLER TEMPS WITHOUT DEEP MIXING...AND WINDS ON THE LIGHTER SIDE WILL NOT HELP MIXING. THAT BEING SAID...TIMING OF STRONGER WAVES THROUGH THE REGION DURING THE LATTER HALF OF THE EXTENDED MAY HAVE IMPACTS ON THIS AS TIMING SHAKES OUT IN LATER RUNS...WITH MORE POTENTIAL FOR PREFRONTAL WARMING IN ADVANCE OF SYSTEM. EXPECT PRECIP CHANCES WILL ALSO FOLLOW SUIT...AS TIMING ISSUES ARE HAMMERED OUT. AAG && .AVIATION... A COLD FRONT WILL MOVE IN FROM THE NORTHEAST TONIGHT AND WILL REACH KLVM BY MORNING. THIS WILL BRING LOWERING CEILINGS AND REDUCED VISIBILITIES AS SNOW WILL DEVELOP ALONG AND WEST OF A LINE FROM KSHR-KBIL TO KRPX. CONDITIONS WILL DETERIORATE TO MVFR CONDITIONS OVERNIGHT WITH IFR CONDITIONS EXPECTED ON FRIDAY. AREAS EAST OF KBIL CAN EXPECT AREAS OF MVFR DUE TO LIGHT SNOW AND LOW CEILINGS. SNOW WILL FALL OVER THE HIGHER ELEVATIONS BRINGING MOUNTAIN OBSCURATIONS LATE TONIGHT THROUGH FRIDAY. RICHMOND && .PRELIMINARY POINT TEMP/POPS... FRI SAT SUN MON TUE WED THU ----------------------------------------------------------- BIL 017/023 009/024 014/035 020/042 023/039 023/038 023/038 39/S 86/S 51/M 11/B 22/J 22/J 22/J LVM 022/032 016/029 019/036 022/040 018/038 020/036 017/036 29/S 97/S 51/M 12/J 22/J 22/J 22/J HDN 013/023 009/028 011/035 020/042 021/040 021/039 020/039 38/S 74/S 31/M 11/B 12/J 22/J 22/J MLS 008/019 902/026 009/033 019/041 022/039 021/038 021/038 22/S 01/U 01/B 11/B 12/J 22/J 11/B 4BQ 009/021 001/029 011/032 019/042 022/040 021/038 021/038 47/S 31/B 11/B 11/B 12/J 22/J 11/B BHK 000/016 905/025 005/030 017/039 019/038 019/035 016/035 20/B 00/U 00/U 11/U 12/J 21/B 11/B SHR 016/025 012/029 013/035 021/042 018/038 019/036 016/036 28/S 74/S 32/J 12/J 22/J 22/J 22/J && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WINTER WEATHER ADVISORY IN EFFECT FROM 6 AM FRIDAY TO 6 AM MST SATURDAY FOR ZONES 34-41-64>66. WY...NONE. && $$ WEATHER.GOV/BILLINGS