Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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197 FXUS65 KTFX 181736 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1136 AM MDT Tue Jun 18 2024 ...Aviation Section Updated... .SYNOPSIS... Widespread precipitation pushes off to the east this morning, with another round of precipitation with a few thunderstorms arriving this afternoon. Daily precipitation chances remain through the forecast period, with better chances arriving Friday. Temperatures gradually warm up, becoming well above average by the weekend. && .UPDATE... The only significant update this morning was to cancel the Winter Weather Advisory for the Southern Rocky Mountain Front a bit early. Otherwise, remaining Winter Weather Advisories will continue through the remainder of the morning. Precipitation trends from being stratiform to more convective in nature this afternoon, with showers and a few thunderstorms becoming numerous across the region by mid afternoon. With snow levels gradually rising through the day today, the expectation is that impacts from snow should largely diminish after noon. -AM && .AVIATION... 18/18Z TAF Period The primary concern this TAF period will be for lingering low clouds, as well as numerous showers and scattered thunderstorms developing this afternoon and early evening. Confidence in timing/location of any thunderstorms was too low to warrant a thunderstorm mention in TAFs at this time, but will be monitored through the afternoon for amendments. The greatest uncertainty this forecast period will be for fog development around daybreak tomorrow. Clearing skies and recent precipitation will be favorable for fog, but the length of clear skies prior to daybreak will ultimately determine who does and who does not get fog. Mountains are likely to be obscured through the evening. -AM Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 511 AM MDT Tue Jun 18 2024/ Today...Widespread rain and mountain snow showers will slowly push off to the east along with the main upper level wave this morning. Snow levels at 4,500ft to 5,000ft can accumulate a few more inches of snow early this morning(mainly on grassy surfaces). As the sun comes up, snow levels will rise back to 6,000-7,000ft. This combined with widespread snow moving out of the area, I`ve kept the Winter Weather Advisories to expire this morning (6am for Central/Southwest MT mountains and 12pm for the Northern Continental Divide). Wind chills will be cold this morning. Lower elevations is forecasted for wind chills to drop into the 20s-30s while mountain locations can drop into the teens. Another upper level disturbance from Canada will push south into the region this afternoon, producing more scattered to widespread showers. A few thunderstorms is also expected with showers this afternoon. These showers can bring up to another 0.1-0.25" of moisture. Showers will taper down during the evening, ending around midnight. Wednesday and Thursday...Northwest flow aloft will transition to southwest flow aloft over the next few days. The southwest flow will help bring in warmer air and help moderate temperatures closer to normal averages. There will be upper air disturbances passing through that will produce isolated showers/thunderstorms (primarily across Central/North Central MT). Precipitation amounts look to be light. The NBM 75th percentile in precipitation amounts shows the CWA receiving up to a 0.1" of moisture for both days. Friday...A small shortwave trough passing through will bring better chances for scattered/widespread precipitation, primarily for central and eastern portion of the CWA. There`s a 40-60% from Central Chouteau, Judith Basin, and Hill Counties and to the east of receiving 0.25" of precipitation. Saturday and beyond...By the weekend, temperatures will be well above normal across the region. We will be monitoring locations across the CWA reaching 90 degrees for the first time this year on Sunday. The climatological average for the first 90 degree day of the year happens on June 23rd for Great Falls and Bozeman, June 26th for Helena, and June 12th for Havre. NBM probabilities are showing a 50-60% for high temperatures reaching 90 degrees around the Helena and Bozeman area, and 30% for the Great Falls area. The beginning of next week brings more low chances for precipitation daily. -Wilson && .PRELIMINARY POINT TEMPS/POPS... GTF 59 37 67 41 / 80 50 30 0 CTB 54 31 64 38 / 80 40 30 0 HLN 61 40 72 46 / 70 40 20 0 BZN 55 33 68 39 / 50 50 10 0 WYS 50 25 62 32 / 60 20 10 0 DLN 55 31 66 37 / 40 40 0 0 HVR 60 41 68 45 / 60 50 30 0 LWT 55 34 65 41 / 90 30 40 10 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon MDT today for East Glacier Park Region-Little Belt and Highwood Mountains-Snowy and Judith Mountains. && $$ http://www.weather.gov/greatfalls