Scientific Forecaster Discussion
000 FXUS65 KTFX 201045 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 444 AM MDT Sun Aug 20 2017 UPDATED AVIATION .SYNOPSIS... West to northwest flow aloft will continue over the region through Monday. Precipitation is not expected, but areas of wildfire smoke will persist. Near-normal temperatures are forecast through Monday. Tuesday and Wednesday will feature above-normal temperatures as high pressure aloft builds-in from the Pacific Northwest. Fair weather will likely persist through mid-week. && .DISCUSSION... Today through Tuesday...Several weather disturbances embedded in westerly to northwesterly flow aloft will cross our region through Monday morning. However, these disturbances should encounter limited moisture and very little, if any instability. Thus, the main affects should be passing mid- to upper-level cloud cover. Decreasing cloud cover from west to east and dry conditions are still expected for Monday's solar eclipse. A high pressure ridge aloft will then build- in from the Pacific Northwest later Monday through Tuesday, allowing fair weather to persist. Near-normal temperatures are in the cards today through Monday night. On Tuesday, highs will be roughly 5-10 degrees above-normal as the aforementioned ridge and associated warmer air build over the area. Tuesday Night through Sunday...Aforementioned high pressure ridge aloft will continue to traverse the CWA from west to east Tuesday night through Wednesday, allowing warming temperatures and primarily dry weather to persist. Somewhat cooler temperatures, along with scattered showers and thunderstorms, remain possible on Thursday and Friday due to an upper-level trough digging southward and eastward from British Columbia. In addition, a Pacific cold front accompanying this trough should sweep eastward over the CWA on Thursday. Drier conditions and slightly warmer temperatures should return next weekend, as another high pressure ridge aloft builds-in from the south and west. Near to slightly above-normal low temperatures are expected throughout the period. High temperatures are forecast to be about 10 degrees above-normal Wednesday, while highs Thursday through next weekend should be near or slightly above- normal. Friday should be the coolest day as our region resides within a post-frontal environment and beneath the aforementioned trough aloft. Jaszka && .AVIATION... Updated 1044Z. Westerly to northwesterly flow aloft and mainly VFR will persist next 24-hours. Several disturbances embedded within the flow will likely be accompanied by nothing more than periods of mid- to upper- level cloudiness. Areas of wildfire smoke and distant mountain obscuration remain possible, especially over Central and SW MT. Smoke may reduce VSBY to MVFR at times, but confidence is low. Jaszka && .FIRE WEATHER... Fire weather highlights are not anticipated through mid-week, but cannot be totally ruled-out due to continued warm, dry, and potentially breezy conditions. Fire weather concerns should increase on Thursday, when the upper-level ridge collapses over Montana and a surface cold front spreads gusty winds and scattered thunderstorms, some dry, over the area. MPJ/Jaszka && .PRELIMINARY POINT TEMPS/POPS... GTF 81 49 81 52 / 0 0 0 0 CTB 78 44 78 47 / 0 10 0 0 HLN 81 52 85 53 / 0 0 0 0 BZN 81 47 84 49 / 0 0 0 0 WEY 75 37 77 36 / 0 0 0 0 DLN 79 46 82 48 / 0 0 0 0 HVR 82 48 81 51 / 0 0 0 0 LWT 79 49 80 50 / 0 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None.