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Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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395 FXUS65 KTFX 170055 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 655 PM MDT Fri Aug 16 2024 .SYNOPSIS... There will be isolated showers and thunderstorms across North- central, Central, and Southwestern Montana today. Sunday through at least the middle of next week there will be isolated showers and thunderstorms. Saturday it begins to warm up and it will be hot for Sunday through at least the middle of next week. && .UPDATE... Given the showers that have moved through the area and clearing skies expected overnight, there is an increased chance for fog development along the hi-line tonight. Widespread dense fog is not expected but patchy fog is possible along river valleys and coulees. Otherwise no major changes were made to the going forecast. -thor && .AVIATION... 16/18Z TAF Period Expect VFR conditions to prevail across North Central and Southwestern Montana, though there will be some brief MVFR conditions due to SHRA and TSRA, especially between 0z/1800MDT and 6z/0000MDT. Expect SHRA/TSRA to be scattered, with any airfield seeing around a 30-50% chance of impacts, with timing at individual airfields outlined in the TAFs. SHRA/TSRA should dissipate after 6z/0000MDT, leaving VFR conditions through Saturday. Ludwig Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 137 PM MDT Fri Aug 16 2024/ This afternoon through Sunday... This afternoon an upper-level ridge is over North-central, Central, and Southwestern Montana. However, an upper-level shortwave moving through the upper-level flow has brought and will bring showers and thunderstorms to the area. This afternoon through tonight in North-central and Central Montana there is a 10 - 40% chance for a tenth of an inch of rain or greater. This afternoon through tonight along the Rocky Mountain Front and adjacent plains there is a 40% chance for a quarter inch of rain or greater. This afternoon in Northern Beaverhead, Gallatin, and Madison Counties there will be isolated showers and thunderstorms. The thunderstorms will produce frequent lightning, gusty erratic winds, and brief heavy downpours(only in North-central Montana). Saturday morning in isolated locations that receive rain this afternoon/evening and where there are clear skies patchy fog will form. On Saturday the upper-level ridge remains over North-central, Central, and Southwestern Montana. On Saturday temperatures warm up to about seasonal averages. On Saturday it will be dry across North-central, Central, and Southwestern Montana. On Sunday the upper-level ridge remains over North-central, Central, and Southwestern Montana. However, an upper-level shortwave moves through the upper-level flow and will bring isolated showers and thunderstorms to the area. On Sunday temperatures will warm up to above seasonal averages. On Sunday there is 50 - 90% chance for the lower-elevations of North- central, Central, and Southwestern Montana north of I-90 having a high temperature of 90 degrees or greater. On Sunday there is a 10% chance for greater than a tenth of an inch of rain across North-central, Central, and Southwestern Montana. Monday through next Friday... On Monday the upper-level ridge remains over North-central, Central, and Southwestern Montana. This will keep hot temperatures across the area. However, an upper-level shortwave moves through the upper-level flow and will bring isolated showers and thunderstorms to North-central, Central, and Southwestern Montana. On Monday there is a 10 - 30% chance for greater than a tenth of an inch of rain across North- central, Central, and Southwestern Montana. On Tuesday the upper- level ridge remains over North-central, Central, and Southwestern Montana. This will keep hot temperatures across the area. However, an upper-level shortwave moves through the upper-level flow and will bring isolated showers and thunderstorms to North-central, Central, and Southwestern Montana. On Wednesday two clusters (48% of ensemble members) show the upper-level ridge remaining over North-central, Central, and Southwestern Montana. The other two clusters (52% of ensemble members) show an upper-level trough moving over the area. This indicates that the weather pattern has a 50% to change or remain the same as on Tuesday across North- central, Central, and Southwestern Montana. On Thursday continuing through next Friday clusters, ensembles, and deterministic models begin to diverge. One scenario is for an upper-level ridge to stay over North-central, Central, and Southwestern Montana. Another scenario is for an upper- level trough to move over the area. A third scenario is for the upper- level flow to be zonal (west to east). This will continue to be monitored for details. -IG && .PRELIMINARY POINT TEMPS/POPS... GTF 53 87 56 90 / 20 0 0 10 CTB 47 82 52 86 / 30 0 10 10 HLN 54 89 58 94 / 30 0 0 10 BZN 47 88 55 93 / 50 0 0 10 WYS 38 80 45 79 / 10 0 20 20 DLN 46 83 52 85 / 20 0 0 10 HVR 55 88 58 96 / 60 0 0 0 LWT 50 85 56 91 / 40 0 0 20 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls