Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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339 FXUS65 KTFX 090653 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1250 AM MDT Thu May 9 2024 .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. && .UPDATE... With this update, some adjustments were made to the precip to better reflect the latest trends in observations and model data. Patchy fog was also added across portions of the hi-line and central Montana for tonight and tomorrow night. Widespread, major visibility reductions are not expected, however, some patches of dense fog are possible overnight along the US-2 and US-87 corridors. -thor && .AVIATION... 1250 AM MDT Thu May 9 2024 (09/06Z TAF Period) Overall, a high pressure ridge building into North Central, Central, and Southwest Montana from the northwest will shift the decreasing flow aloft more northeasterly, and surface high pressure will keep winds fairly light through at least 10/06Z. However, low-level wind shear will persist in the KWYS area through around 12Z. Details: North-central Montana (KCTB, KHVR): VFR conditions will continue through the period as mid-level cloudiness decreases. Isolated showers will move out of the KHVR area by 09Z, and the partial clearing will allow patchy fog to form between 08Z and 16Z, possibly reducing visibility to MVFR at times. Central (KGTF, KHLN, KLWT) and Southwest (KBZN, KEKS, KWYS) Montana: Mountain-obscuring MVFR/IFR conditions with areas of fog and scattered rain and mainly mountain snow showers will continue across the area through at least 00Z. Clouds are expected to start lifting and breaking up after then. However, LIFR ceilings with periods of dense fog will linger at KLWT through around 18Z. -Coulston Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 600 PM MDT Wed May 8 2024/ 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 && .PRELIMINARY POINT TEMPS/POPS... GTF 34 56 33 64 / 70 40 0 0 CTB 31 59 31 70 / 20 0 0 0 HLN 39 56 36 70 / 70 30 0 0 BZN 33 51 31 64 / 80 50 10 0 WYS 28 51 25 61 / 40 30 0 0 DLN 35 55 33 66 / 70 20 0 0 HVR 40 64 38 70 / 50 20 0 0 LWT 32 48 31 58 / 100 50 10 0 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until midnight MDT tonight for Gallatin Valley-Madison River Valley-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-Little Belt and Highwood Mountains-Snowy and Judith Mountains. && $$ http://www.weather.gov/greatfalls