Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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077 FXUS65 KTFX 090000 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 600 PM MDT Wed May 8 2024 .Aviation Section Updated... .SYNOPSIS... Snow and rain will end from northeast to southwest by Thursday morning. Across North-central and Central Montana patchy dense fog is possible this evening through Thursday morning in areas where skies clear. North-central, Central, and Southwestern Montana will dry out and warm up Thursday afternoon through the weekend. By the middle of next week the weather pattern could change. && .DISCUSSION... This afternoon through Thursday... Rain/snow will continue through the evening along the Highway 200 Corridor and south. Precipitation will end from northeast to southwest by Thursday morning. There will also be isolated rain showers across North-central Montana through this evening. Snow will continue along the Southern Rocky Mountain front through this evening. Patchy dense fog has formed in Northern and Central Fergus County and will continue through Thursday morning. At times visibility will be reduced to a quarter mile or less. Patchy dense fog could form in other locations of Central and North-central Montana if skies clear overnight due to all the moisture from this system. A Winter Weather Advisory has been issued for the Madison River Valley and Gallatin Valley until midnight due to snowfall reducing visibility down to a half mile at times. The Blizzard Warning for the Little Belts and Highwood Mountains has been downgraded to a Winter Storm Warning due to the strong winds and wind gusts having ended. The snow has ended for the Highwood Mountains. The Winter Storm Warning along the Northern Rocky Mountain front has been cancelled due to the snow having ended. The Winter Storm Warning along the Southern Rocky Mountain Front has been downgraded to a Winter Weather Advisory. For more details see the TFX WATCHES/WARNINGS/ADVISORIES section below. On Thursday an upper- level trough begins to move out of the area. This will begin to warm up and dry out North-central, Central, and Southwestern Montana. Friday through Sunday... On Friday an upper-level ridge begins to move over North-central, Central, and Southwestern Montana. This will warm temperatures up to about seasonal averages across the area. This upper-level ridge will stay in place above North-central, Central, and Southwestern Montana through the weekend which will keep temperatures dry and allow temperatures to warm up to above seasonal averages across the area through the weekend. Isolated locations of North-central and Central Montana and the Helena Valley have a 50 - 65% chance for having temperatures of 80 degrees or warmer. Monday through next Wednesday... On Monday cluster analysis indicates that there will be upper-level zonal flow over North- central, Central, and Southwestern Montana. This will keep the area`s weather about the same on Monday as Sunday. On Tuesday three clusters (86% of ensemble members) have a week upper-level trough over North-central, Central, and Southwestern Montana. One of the clusters (14% of ensemble members) has an upper-level ridge over North-central, Central, and Southwestern Montana. This indicates that the weather pattern could change on Tuesday. Next Wednesday the ensembles begin to diverge and so the weather over North-central, Central, and Southwestern Montana is uncertain at this time. -IG && .AVIATION... 600 PM MDT Wed May 8 2024 (09/00Z TAF Period) North-central Montana (KCTB, KHVR): VFR conditions will prevail through the TAF period with some vicinity rain showers near KHVR possible through 09/09Z. Otherwise, the precipitation will continue progressing southward away from the hi-line. Gusty winds are expected to continue through around 09/03Z before tapering off below 15kts. Central Montana (KGTF, KHLN, KLWT): MVFR conditions are expected to prevail at KGTF and KHLN through at least Thursday morning with the possibility of IFR or lower in passing rain showers. Mountains and passes will be obscured through much of the TAF period. Meanwhile at KLWT, fog and low clouds are expected to prevail through at least Thursday morning with IFR or lower expected during this time. There is a possibility of fog developing around KGTF, however, at this time confidence was not high enough to include it in the TAFs. Southwest Montana (KBZN, KEKS, KWYS): Rain and snow showers are expected to impact KBZN and KEKS through most of the TAF period with IFR or lower possible through the period. KWYS will generally stay dry and fluctuate between VFR and MVFR through the TAF period. Mountains and passes will be obscured through at least Thursday afternoon. -thor Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .HYDROLOGY... The flood warning will continue for Clear Creek, as the creek has risen into major stage earlier today. Additional runoff from the Bears Paw Mountains will continue to produce minor flood impacts from other small streams and creeks, such as Big Sandy Creek and Beaver Creek. Areas of minor flooding have been reported around Beaver Creek, along with locations around Hays and Lodge Pole. Thus the areal flood advisory will continue for portions of North Central MT until Thursday afternoon. For areas further south and west, most of the higher elevations have had just snowfall recently, thus runoff from the recent snowfall will begin in a few days as warmer air moves back in. Since most river levels are currently low, impacts should be minor from any new flooding that develops. Brusda && .PRELIMINARY POINT TEMPS/POPS... GTF 34 56 34 64 / 80 40 0 0 CTB 31 59 33 70 / 10 0 0 0 HLN 40 58 37 70 / 60 30 0 0 BZN 34 55 31 64 / 70 50 10 0 WYS 30 53 26 61 / 40 30 0 0 DLN 37 56 34 66 / 50 20 0 0 HVR 41 66 38 70 / 40 20 0 0 LWT 32 48 31 58 / 90 50 10 0 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until midnight MDT tonight for Southern Rocky Mountain Front. Winter Storm Warning until midnight MDT tonight for Big Belt, Bridger and Castle Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Snowy and Judith Mountains. Winter Weather Advisory until midnight MDT tonight for Gallatin Valley-Madison River Valley. Winter Storm Warning until midnight MDT tonight for Little Belt and Highwood Mountains. && $$ http://www.weather.gov/greatfalls