833 FXUS65 KTFX 082346 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 440 PM MST Thu Jan 8 2015 AVIATION SECTION UPDATED .DISCUSSION... Tonight through Saturday...Snow gradually ending this afternoon as the last of the snow bands move across the area. The winter weather advisory will be allowed to expire at 3 pm. A few snow showers may linger into the evening over Meagher and Judith Basin counties but any additional amounts will be small. With skies beginning to clear from the north, temperatures will fall below zero over most areas, the exception being southwest Montana where warmer air will reside. An upper ridge builds over western Montana Friday. Northwest flow aloft will continue over the area but will be dry. Temperatures will remain cool and below seasonal averages Friday afternoon. By Saturday afternoon, the next disturbance will begin to affect the area. Snow will develop over the northern Rockies and then spread east over Hi-Line during the afternoon. Temperatures will climb into the 30s Saturday afternoon. Saturday night through Thursday...Medium range models have trended toward a wetter pattern for Saturday night and Sunday. This comes about due to a disturbance embedded in a moist northwesterly flow aloft coupled with the arrival of a backdoor cold front. Previous model runs had shunted this boundary eastward and only showed a slight chance of mountain showers. The chances of snow have been further increased such that the forecast is for snow to be likely over a good portion of the east slopes of the Rocky Mountains. Also lowered high temperatures for Sunday from those of the previous forecast. At this time there appears to be a potential for an inch or two of snow accumulation over the plains with 3 to 6 inches in the mountains. As this system moves out of the region, a split flow aloft will sweep another disturbance into the Great Basin where is strengthens into a winter storm over the Four Corners region Tuesday and Tuesday night. Flow aloft behind this storm will buckle northward and develop into a relatively strong ridge over the Pacific Northwest (and/or the Northern Rockies depending on model). This will lead to a generally dry north to northwest flow aloft over Montana with temperatures expected to warm back up toward seasonable values. mpj/jmb && .AVIATION... UPDATED 2340Z. Latest satellite imagery shows extensive low- and mid-level BKN/OVC cloud decks from a weather system that passed through earlier today are slowly dissipating across central and southwest MT. Current line marking mostly clear skies will move through KCTB/KHVR by 01Z and gradually work south this evening. Kept in mention of VCSH and TEMPO -SN with MVFR/IFR ceilings at KBZN and KLWT for another few hours, though precipitation is currently too light to even show up on radar. All terminals should be back to VFR by 03-04Z with widespread clear skies and light winds expected overnight. Waranauskas && .PRELIMINARY POINT TEMPS/POPS... GTF -10 20 17 32 / 10 0 10 10 CTB -12 16 9 24 / 10 0 10 20 HLN -1 24 19 34 / 10 10 10 10 BZN -4 24 14 35 / 10 10 10 10 WEY -2 30 16 32 / 10 10 20 30 DLN 12 34 24 39 / 10 10 10 10 HVR -19 4 -3 20 / 0 0 20 20 LWT -13 24 17 33 / 10 0 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls www.twitter.com/NWSGreatFalls www.facebook.com/NWSGreatFalls