952 FXUS65 KTFX 271031 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 430 AM MDT Thu Jun 27 2013 .DISCUSSION... 430 AM update...With Logan Pass continuing to show wind gusts near warning criteria this morning...have decided to issue a high wind watch for later this evening through mid day Friday for higher elevations of Glacier National Park. Mid level winds should continue to decrease through the morning hours today...so no high wind highlight planned for today at this time...but for this evening...mid level wind speeds should increase to 40 to 55kts and these stronger wind speeds could mix down to the ridge tops...causing some high wind gusts in this region. Brusda Earlier 330 AM update... Today through Saturday...The much advertised upper level ridge of high pressure is starting to build over Montana this morning...as drier and more stable air has pushed as far north as the Butte area. A Chinook arch is trying to develop near the top of the ridge...as a few morning sprinkles continue along the divide from the left over Pacific moisture moving northeastward through the region. With the upper level ridge continuing to build through the day...mostly dry conditions and warmer temperatures are expected to start to move into the region today. Additionally...it will not be quite as windy as it has been. The warmer air will continue to move into the region on Friday...with most areas seeing afternoon temperatures from 8 to 14 degrees above normal. There will also be a small chance for an isolated late afternoon/early evening thunderstorm near the MT/ID border over SW MT on Friday. However...most of the thunderstorm activity should be confined to mountain areas. For Saturday...afternoon temperatures will continue to warm just a touch more when compared to Friday...allowing for one of the hottest days of the year so far. However...forecast models do allow for rather an unstable airmass to develop by the afternoon hours over a good portion of the region. With a weak upper level disturbance moving through the upper level ridge...there will be a chance for thunderstorms for most areas by late afternoon. Some storms could be strong...especially West of Interstate 15...and we will continue to monitor this. Brusda Saturday night through Thursday...Confidence in the medium range forecast is beginning to increase as models finally come into agreement for next week. A strong upper level ridge will be over the western USA this weekend, with the ridge axis extending north through Montana into Saskatchewan and Alberta on Saturday night. The GFS remains consistent run-to-run showing enough shortwave energy pushing over the top of the ridge for isolated to scattered thunderstorms Saturday evening and pops have been bumped up accordingly. From Sunday through early Tuesday the upper level ridge gradually builds in strength, but will also regress toward the west coast putting Montana into a northerly flow aloft. As the upper level ridge continues to amplify over western Canada, shortwave energy from the Yukon becomes entrained into the northerly flow on the backside of the ridge. Simultaneously, a westerly jet streak over Alaska combines with a second jet streak pushing north along the front side of the ridge. This combination causes the top of the ridge axis to shear eastward with a cyclonic flow aloft developing along the backside of the ridge and enhancing the previously mentioned shortwave. By Wednesday, an east to west oriented trough develops over eastern and central Montana for cooler temperatures and isolated thunderstorm activity. As a result of greater forecast confidence I have opted to increase temperatures for Sunday through Tuesday but have tweaked them downward for Wednesday and Thursday. As previously mentioned, I have also increased pops into the chance category for Saturday evening, and have kept periods of isolated pops in the forecast for the remainder of the medium range. Feel that if future model runs continue to show agreement than pops may need to be bumped up further for Wednesday and possible the Fourth of July as well. mpj && .AVIATION... Updated 0500Z VFR conditions will prevail for the next 24 hours. Mid and upper level clouds along will persist across the forecast area overnight. Isolated showers are possible after 21z over higher terrain near KBZN and KHLN but coverage looks to be very limited. Any showers will cause mountains to be obscured at times. Mid and upper clouds will increase after 16z and winds will become breezy once again. && .PRELIMINARY POINT TEMPS/POPS... GTF 83 57 90 59 / 0 0 0 0 CTB 79 53 86 56 / 0 0 0 0 HLN 85 59 93 61 / 0 0 0 0 BZN 87 53 94 54 / 0 0 10 10 WEY 81 44 84 45 / 0 0 10 10 DLN 86 53 88 56 / 0 0 10 10 HVR 84 57 90 58 / 0 0 0 0 LWT 79 53 84 55 / 0 0 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls