843 FXUS65 KTFX 020510 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1109 PM MDT Wed Aug 1 2018 UPDATED AVIATION .UPDATE... Evening update has been published, with only minor tweaks made to POPs to account for recent radar trends and Hi-Res model guidance. Scattered thunderstorms have been steadily moving east across portions of Southwest and Central Montana this afternoon and evening, generally along and south of a Lincoln, to Stanford, to Lewistown line. Wind gusts to around 50 mph and occasional cloud-to-ground lightning strikes have been the primary observed hazards with these storms. While some locations have observed precipitation beneath these storms, it will remain to be seen if any new fire starts have occurred from this recent wave of storms. Thunderstorm and shower activity is expected to decrease in areal coverage to primarily the mountains of Southwest Montana after midnight tonight as the best forcing/lift slides east of the region. With regards to the Red Flag Warning that was in effect for Fire Weather Zone 112 (Glacier and Western Pondera Counties) until 9pm this evening; the warning will be allowed to expire at 9pm this evening (Wednesday, August 1st). Winds across the warned area have decreased below critical values and relative humidity values are slowly recovering. While relative humidity values are slowly recovering and will continue to recover throughout the nighttime hours, recovery across Fire Weather Zone 112 will be poor to very poor, with maximum relative humidity values only reaching 40 to 60 percent overnight. Otherwise, the Red Flag Warnings for all Fire Weather Zones across North Central and Central Montana on Thursday and Friday remain unchanged. - Moldan && .SYNOPSIS... Hot temperatures today under a high pressure ridge may cause a few thunderstorms to develop this afternoon and evening over and near the mountains of southwest and central Montana. Some of the stronger storms may produce gusty winds, brief heavy rain, and small hail. A disturbance with a Pacific cold front will likely cause gusty west winds to spread over the plains on Thursday, with a few thunderstorms possible over southwest Montana. Gusty winds and warm temperatures will likely persist into Friday. && .AVIATION... Updated 0509Z. Mainly VFR and westerly flow aloft persist next 24-hours as multiple disturbances in the low- to mid-level atmosphere traverse the area. Isolated to scattered showers and thunderstorms are expected, especially between 18Z/Thurs and 06Z/Fri. Areas along and especially south of a KHLN to KLWT line have the best chance of being impacted by this activity. Brief MVFR and erratic surface wind gusts up to 30 to 50 knots are possible in/near these showers and storms. Breezy southwesterly to westerly regional winds are expected after 15Z/Thurs to about 02Z/Fri, especially on the plains of north- central Montana and along the Rocky Mountain Front, as a cool front sweeps eastward through the area. - Moldan/Jaszka && .FIRE WEATHER... A few thunderstorms, some of which may be on the dry side, will be possible this evening over parts of north-central, central, and southwest Montana. Winds will decrease overnight as humidity recovers, but critical fire weather conditions will expand further out across the plains on Thursday as winds increase and very low humidity levels develop. A dry Pacific cold front will then move through the area Thursday night, which will spread gusty west winds over much of the plains of north central Montana on Friday. NWS Missoula also has a Red Flag Warning in effect from noon through 9 pm for fire weather zones 110 and 111, including portions of Jefferson, Madison, and Beaverhead Counties, for a scattered mix of wet and dry thunderstorms that could produce strong gusty winds and dry lightning. && .PREV DISCUSSION... /ISSUED 525 PM MDT Wed Aug 1 2018/ Rest of This Afternoon through Thursday Night...Upper ridging continues over the region with embedded disturbances moving across the area. A few isolated and mostly dry thunderstorms are expected to develop primarily this evening over the mountain areas of southwest, central, and perhaps even north-central Montana, and some of those storms could produce wind gusts in excess of 40 mph. A shortwave low pressure trough will then approach Montana on Thursday to increase winds aloft, which may help spread gusty winds over more of the plains and increase fire weather concerns yet again. However, this shift to a more westerly flow aloft will focus additional afternoon/evening thunderstorms more so over southwest Montana on Thursday. Temperatures on Thursday will likely cool a few degrees over those on Wednesday, but most lower elevations will still reach 90 degrees. Friday through Sunday...Model guidance is now in general agreement that multiple shortwave disturbances will traverse our region generally from west to east this Friday through the weekend. Enhanced flow aloft accompanying this pattern and diurnal mixing of the boundary layer will promote breezy southwesterly to westerly surface winds on Friday, which may contribute to critical fire weather conditions. Isolated showers and thunderstorms remain possible through this weekend, especially over and near higher terrain. Near-normal highs on Friday will be followed by slightly below-normal readings for the weekend, while lows remain near-normal through the period. Monday through next Wednesday...High pressure aloft builds from the west, allowing low and high temperatures to trend near or slightly above-normal. Simultaneously, this stabilizing ridge will promote drier weather for our region. && .PRELIMINARY POINT TEMPS/POPS... GTF 59 96 55 87 / 20 10 10 10 CTB 55 92 51 82 / 10 10 10 10 HLN 60 96 57 86 / 20 10 10 10 BZN 56 92 52 86 / 20 20 20 10 WEY 48 80 49 78 / 50 30 20 20 DLN 53 90 50 84 / 60 20 10 10 HVR 61 98 58 90 / 10 0 0 0 LWT 60 90 55 84 / 20 10 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 10 AM Thursday to midnight MDT Friday night Central and Eastern Lewis and Clark National Forest Areas...Chouteau and Fergus Counties...Eastern Glacier/Toole/Central/Eastern Pondera/Liberty...Helena and Townsend Ranger Districts of the Helena National Forest...Hill and Blaine Counties...Lewis and Clark National Forest Rocky Mountain District-Rocky Mountain Front...Lincoln Ranger District of the Helena National Forest. Red Flag Warning from noon to 10 PM MDT Thursday Eastern Beaverhead National Forest. Red Flag Warning from noon to 10 PM MDT Thursday Deerlodge/Western Beaverhead National Forest. && $$ http://www.weather.gov/greatfalls