852 FXUS65 KBYZ 190255 AFDBYZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 855 PM MDT MON MAR 18 2013 .SHORT TERM...VALID FOR TUE AND WED... ISOLATED SNOW SHOWERS/FLURRIES CONTINUE ACROSS THE AREA THIS EVENING AS WE REMAIN UNDER AN UNSTABLE NW FLOW...THOUGH COVERAGE HAS DECREASED SOMEWHAT SINCE WE LOST DAYTIME HEATING. WEAK SHORTWAVE NOW MOVING THROUGH WESTERN MT WILL COMBINE WITH A CANADIAN COLD FRONT TO ENHANCE THE SNOW SHOWER ACTIVITY LATER TONIGHT INTO TUESDAY MORNING...ESPECIALLY IN CENTRAL PARTS AND NW UPSLOPE AREAS. LOW LEVEL TEMP PROFILE WILL BE FAVORABLE FOR DENDRITIC GROWTH SO WILL NEED TO KEEP WATCH OF THIS...AS CONVERGENCE ALONG FRONTAL BOUNDARY COULD BE A FOCUS FOR SOME LIGHT SNOW ACCUMULATION. BELIEVE WINDS AT BILLINGS WILL SHIFT TO THE NE PRIOR TO THE PASSAGE OF THE SHORTWAVE AROUND MIDDAY TUESDAY...SO POTENTIAL FOR SNOW SHOWERS SHOULD PERSIST AROUND THE METRO AREA FOR A FEW HOURS BEYOND SUNRISE. HAVE TWEAKED POPS ACCORDINGLY. SNOW SHOWER ACTIVITY WILL DIMINISH BY TOMORROW AFTERNOON AS ENERGY EXITS TO THE SOUTHEAST AND RIDGING COMMENCES FROM THE WEST. HAVE ALSO TWEAKED TEMPS AND WINDS SLIGHTLY. BAKER ALREADY DOWN TO 17 PER LIGHT WINDS AND SNOW COVER IN OUR FAR EAST...SO HAVE DROPPED EXPECTED LOWS A FEW DEGREES...THOUGH TEMPS MAY JUMP SLIGHTLY ONCE NW WINDS HIT LATER TONIGHT. JKL .LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON... WEATHER ACROSS THE REGION WILL RETURN TO A MORE UNSETTLED STATE BY THE END OF THE WEEK... EXTENDED PERIOD BEGINS ON THURSDAY AS AN UPPER LEVEL RIDGE BREAKS DOWN AND GIVES WAY TO BROAD NORTHWESTERLY FLOW. IN A VERY SIMILAR PATTERN TO WHAT THE MODELS WERE PROGGING A WEEK AGO FOR THE WIDESPREAD WIND EVENT THAT OCCURRED YESTERDAY...AN UPPER LEVEL JET WILL DIG ITS WAY INTO SOUTHERN IDAHO...PUTTING MUCH OF WESTERN MONTANA INTO THE LEFT EXIT REGION BY THURSDAY MORNING. UPPER LEVEL Q VECTOR FORCING WILL ALSO ALIGN ITSELF ALONG A NORTH TO SOUTH AXIS OVER CENTRAL MONTANA AROUND THE SAME TIME. AT THE SURFACE...IN RESPONSE TO THE UPPER LEVEL JET...PRESSURES WILL ACT TO FALL ACCORDINGLY AND GENERATE SOME FAIRLY STRONG WINDS ACROSS THE CENTRAL AND EASTERN ZONES. A SURFACE COLD FRONT WILL ALSO ENHANCE LIFT AS IT MOVES IN FROM THE NORTHWEST...MAKING THINGS QUITE BREEZY...WETTER AND COOLER. AS FAR AS MODEL CONSISTENCY...THE ECMWF AND GFS ARE IN FAIRLY DECENT AGREEMENT WITH THE LONG WAVE PATTERN. THE GFS SEEMS TO BE A LITTLE BIT MORE AGGRESSIVE WITH THE AMOUNT AND SPEED OF THE ENERGY AVAILABLE...WHILE THE ECMWF IS A BIT MORE RESERVED. THIS PATTERN ONCE AGAIN FAVORS SNOWFALL FOR OUR MOUNTAINOUS REGIONS...AND THE HISTORICAL CIPS ANALOG GUIDANCE TENDS TO HIGHLIGHT THE BIGHORNS AND BEARTOOTH MOUNTAINS ACCORDINGLY. SO AS A RESULT...DECIDED NOT TO NARROW DOWN THE HIGHEST PRECIPITATION CHANCES TO JUST ONE FORECAST PERIOD JUST YET. KEPT WITH TREND OF BUMPING UP POPS ON THURSDAY...AND WILL KEEP AN EYE ON THE FORECAST OVER THE NEXT FEW MODEL CYCLES BEFORE ZONING IN ON ONE PARTICULAR PERIOD. FOR TEMPERATURES...POPULATED THE DAYTIME MAXES WITH THE BCCONSALL MODEL AND THE NIGHTTIME MINS WITH MOSGUIDEBC. AFTER A BRIEF WARMING TREND EARLIER THIS WEEK...TEMPS WILL FALL BACK TO JUST BELOW NORMAL ACROSS THE CWA. LONGWAVE TROUGHINESS WILL CONTINUE THROUGH THE WEEKEND AND INTO NEXT WEEK AS A SERIES OF SHORTWAVES CONTINUE TO MAKE THEIR WAY INTO THE REGION. SINGER && .AVIATION... WINDS HAVE DECREASED ACROSS THE AREA SINCE SUNSET...AND SHOULD STAY LIGHTER WITH GUSTS OF 20 KTS OR LESS THROUGH THE REMAINDER OF THE NIGHT AND TUESDAY. ISOLATED TO SCATTERED SNOW SHOWERS WILL IMPACT THE REGION THROUGH MIDDAY TUESDAY...WITH LOCALIZED REDUCTIONS TO MVFR FLIGHT CONDITIONS. THE HIGH TERRAIN WILL BE FREQUENTLY OBSCURED IN SNOW SHOWERS. JKL && .PRELIMINARY POINT TEMP/POPS... TUE WED THU FRI SAT SUN MON ----------------------------------------------------------- BIL 023/038 026/054 031/042 028/038 024/044 025/040 026/039 22/J 01/E 44/W 32/W 21/B 12/W 22/W LVM 022/041 026/053 034/042 025/041 020/038 020/038 021/038 21/B 12/W 54/W 32/W 22/W 22/W 22/W HDN 021/039 024/055 028/043 027/038 026/043 025/041 026/040 32/J 01/B 45/W 42/W 21/B 12/W 21/B MLS 019/034 021/050 025/038 026/037 025/042 024/040 024/041 21/B 01/B 25/W 42/J 21/B 12/W 21/B 4BQ 019/035 020/049 024/039 024/036 024/040 023/039 024/040 32/J 00/B 15/W 42/W 21/B 12/W 21/B BHK 013/028 014/040 018/031 020/034 020/036 020/035 020/035 21/N 00/N 14/J 42/J 21/B 12/J 21/E SHR 017/033 017/051 026/039 022/034 019/038 018/036 019/034 22/J 01/B 26/W 43/J 22/J 23/W 31/E && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS