603 FXUS65 KPIH 150920 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 220 AM MST Fri Nov 15 2019 .SHORT TERM...Through Saturday night. A Pacific trough and attendant cold front remains on track to swing through SE Idaho tonight into Saturday morning. Ahead of the trough, breezy and mild conditions will be the rule by this afternoon, with highs reaching 60 or the low 60s across the southern Snake Plain and eastern Magic Valley. Winds will peak this evening just ahead and behind the cold frontal passage, with SW-W wind in the 15-25 mph, with occasionally higher gusts across the southern Snake Plain and eastern Magic Valley. The traditionally winder locations like I-84 from Burley south to Sweetzer Summit as well as unsheltered mid/upper slope locations will experience gusts around 45 mph. Winds will subside Saturday evening. In terms of precipitation, the arrival time has slowed a couple of hours, with snow showers not expected to arrive across the central Idaho mountains until shortly before midnight, with snow showers overspreading the Continental Divide/Island Park region shortly after midnight. Showers will end across the central Idaho mountains Saturday morning while at the same time expanding across the higher terrain areas between the Snake Plain and Wyoming border. Briefly moderate snow showers will be possible Saturday morning from Island Park south to Pine Creek Pass and favored slopes between Palisades and the Bear Lake range. Showers are then forecast to end Saturday afternoon. At most, 1-2 inches of snow are forecast mainly above 7000 feet across the Wyoming border region and mainly above 8000 feet across the central Idaho mountains. This is above most mountain passes with the exception of Targhee, Pine Creek and Banner, and some brief slushy conditions will be possible here Saturday morning. Outside of these areas, little/no impacts are expected from this cold frontal passage. High temperatures Saturday will drop around 10 degrees from today's highs. AD .LONG TERM...Sunday through next Friday. The operational and ensemble models were in fairly good agreement this morning with a ridge remaining the dominant player over the NWRN states early in the forecast cycle supporting mainly dry conditions. A Pacific trough digs into the NW coast as early as Tuesday morning while attending precipitation translates into the CNTRL mountains Tuesday afternoon and to a lesser extent the remainder of SE Idaho Tuesday night as the NRN portion of the trough shears east along the Canadian border and the SRN extent spins off a closed low over the NRN Great Basin somewhere (lots of model uncertainty was noted on the position of that low). SE Idaho remains under the influence of this split Wednesday and Thursday as the aforementioned low continues to deepen and settle south into SRN California. Thus a chance to slight chance mention of precipitation remains in the forecast Tuesday through Thursday. By Friday, drier conditions were expected to filter into the region from the north as the low slipped east through the 4-corners region and the ridge rebounded off the NW coast. There is still a great deal of uncertainty with the evolution of the pattern next week as the models continue to flash varying solutions from one model run to the next. Daytime highs generally remain above normal through mid-week and then begin to slide to near normal readings by Friday. No guarantees here either. Huston && .AVIATION...A weak low pressure trough will migrate through the region tonight. Increasing mid- and upper-clouds will advance across the area ahead of the trough today with lower VFR CIGS anticipated overnight. Light upslope showers are anticipated in the CNTRL and NE mountains by midnight and continuing through Saturday morning. It does not look like SUN will be impacted but we may see VCSH and a brief period of MVFR CIGS at DIJ Saturday morning. Huston && .AIR STAGNATION...Poor ventilation conditions are likely across the Snake River Plain and valleys of Southeast Idaho through this morning with lingering light winds and inversion conditions. This will lead to pockets of degraded air quality through this morning. As mentioned in the previous discussion, the incoming trough and cold front will promote breezy conditions this afternoon along with eroding inversions for all but the deepest valleys, with good mixing expected Saturday as well behind the cold front. This will improve air quality. Therefore, an air stagnation advisory will not be necessary at this time. AD/NP && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$