726 FXUS65 KTFX 281736 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1036 AM MST Sat Dec 28 2019 Updated Aviation Discussion .UPDATE... Previous forecast remains generally on track with just a minor update this morning. Mid-level cloud-cover remains fairly widespread across all but far NW portions of the forecast area this morning and with only very slow movement of the mid level trough axis eastward today, clouds may linger a bit longer into this afternoon for areas along and east of I-15. Radar shows some very weak returns under these clouds as well and a few flurries or very light snow showers possible, mainly across southeast and eastern portions of the forecast area. Hoenisch && .SYNOPSIS... Passing disturbances will bring periods of clouds to the state. Some snow showers are possible, primarily to mountain areas of central and western Montana over the next few days. Overall, temperatures will be near seasonal normals over the region through the weekend, then begin a warming trend next week. && .AVIATION... Updated 1036 AM MST Sat Dec 28 2019 (28/18Z TAF issuance) Mid level clouds covering most of north central and SW MT will erode from NW to SE today with VFR conditions prevailing at most terminals. Some flurries or light snow showers could affect areas from KEKS to KLWT and southeast through mid afternoon with periods of MVFR and mountain obscuration and these conditions could continue later into the early evening at KWYS. Generally quiet conditions overnight tonight are followed by an increase in clouds from the west and a chance for light snow showers again over western and southwest areas by Monday morning. Hoenisch && .PREV DISCUSSION... /ISSUED 512 AM MST Sat Dec 28 2019/ Today through Sunday... Overcast skies are noted across much of central and SW MT this morning, courtesy of a sharp upper trough crossing the Rockies. However, any stray snow showers should largely remain in the mountains today. The main concern this weekend is late tonight night into Sun in association with another disturbance digging south across the area within an overall highly-amplified upper- level pattern. This disturbance could result in a band of light snow over the western and southwestern portions of the CWA. Model guidance has shifted a bit further west with the expected areas of higher QPF, keeping the bulk of impactful snow west of the Divide in MSO's CWA. The current forecast has an inch or less of snow for pass level and below for almost all of the CWA, with the exception of 1 to 3 inches for Chief Joseph Pass in NW Beaverhead. At this time, advisories don't appear necessary. Overall, temperatures will be near or just a touch warmer than seasonal normals through the weekend. -Kredensor/Cassell 20 Monday through next Saturday... Highly amplified upper-level pattern continues but with increasing influence of upper ridging to begin the week. This will result in a warming trend despite northerly mid-level flow, as sfc flow will be southwesterly and increasing through Tuesday. Winds on Tue will be gusty across the north-central Plains, with peak gusts at lower elevations over 30kts seeming likely. By Tue night into Wed, the upper flow flattens with a disturbance crossing the region that will produce precipitation, especially over the Rocky Mountain Front and across Southwest MT. Given relatively warm sfc temperatures and much colder air aloft, precipitation over north-central MT will likely be more banded and convective in nature, with rain and snow and perhaps even some graupel with the stronger showers. Snow accumulations in the mountains Wed into Wed night could reach 3 to 6 inches in some areas along the Divide and for parts of SW MT, with winter highlights possibly needed. Additionally, windy conditions later Wed could turn into a widespread high wind event over Central and North Central MT later Thu into Fri, with temperatures continuing to warm to well-above normal levels by the end of the week. At the same time, there are indications of a potentially significant system accompanied by ample Pacific moisture impacting the region Thurs afternoon thru Fri evening, which could bring significant snowfall to much of the Continental Divide. Due to downsloping and warmer lower elevation temperatures, it seems probable that impactful snowfall will not extend much beyond the Divide and Rocky Mountain Front area. Given the long lead-time, significant uncertainty exists on the details of potential snowfall, so this will need to be monitored closely in the coming days. -Kredensor/Cassell && .PRELIMINARY POINT TEMPS/POPS... GTF 32 15 31 17 / 10 0 10 10 CTB 30 12 30 16 / 0 0 10 10 HLN 29 12 29 13 / 0 10 30 10 BZN 26 6 26 9 / 20 10 30 10 WYS 18 -6 16 -5 / 10 10 40 10 DLN 22 3 25 8 / 10 20 40 20 HVR 29 9 25 10 / 0 0 10 0 LWT 28 12 30 14 / 20 0 10 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls