Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
024 FXUS65 KBYZ 230749 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 149 AM MDT Thu May 23 2024 .DISCUSSION... Today through Friday night... ...Key Messages... - Heavy precipitation for lower elevations and heavy snow for mountains today lingering early this evening. - Heavy rain will cause rises on area rivers and streams. Water vapor imagery was showing a strong upper low over central Idaho. Models have locked in with the timing and position of this upper low movement today and tonight. The low tracks across northern Wyoming, which is a little farther south than previous tracks. This slides the heaviest precipitation a little farther south, with the biggest QPF totals generally over the mountains and foothills of the western and central zones. Strong dynamic forcing will produce moderate to heavy rainfall today, with the focus for that over western and central zones through 18z today, then the eastern parts of central zones (think Sheridan county into southern Big Horn county and southern Rosebud county east) and into southeast zones. Amounts along the foothills from say just south of Columbus to Fort Smith to Lodge Grass and Ashland, south could pick up 1.5 to 2 inches of rainfall today. NBM was giving Billings a 70% chance of picking up over 1 inch of rainfall today, same with Red Lodge and Sheridan. The highest probability of this (over 80%) was over southern Big Horn county. Sections of Big Horn county has flood guidance of around 1.5 inches over 6 hours, would be under the forecast amounts in these locations, but not by a great deal. WPC has placed a marginal risk of flooding from eastern Yellowstone county eastward, to cover Big Horn county, Sheridan county, and all of southeast Montana. This seems reasonable given the dynamics of the system. Will have to keep a close eye on rain rates today, as heavier amounts might cause very quick rises on small streams. The Flood Watch for the Little Big Horn River near Hardin continues from this evening to Saturday afternoon. The system was coming in gradually warmer with each passing run it seems, so the snow threat is mainly for elevations above 6000 feet. Snow levels will fall to around 5000 this morning, so there will likely be snow this morning over the foothills and higher hills of western and central zones, but 850mb temperatures stay above 1c. That and a high sun angle, should keep the snow factor in these areas brief. Dynamic cooling may play a factor in changing precipitation over to snow and keeping it as snow longer than expected. That being said, temperatures were starting out in the 40s to lower 50s early this morning, so have a ways to go to get there. Will not issue any additional winter highlights at this time, given the uncertainty of snow impacts below 5000 feet but will keep a close eye on radar and webcam trends. NBM probabilities for 2 inches of snow at Red Lodge was 30%. A quick Winter Weather Advisory may be needed should rain change to snow quickly and actually impact road conditions with more than a dusting of slush. Leaves have come out in full, so this could be a factor too, but the high sun angle should allow most of the that to melt off of the trees as falling (unless snowing heavenly for a few hours straight). Will watch closely as the morning progresses. The upper low pulls into the western Dakotas late this afternoon and early this evening, so will linger high PoPs (60-80%) over the eastern zones, while tapering back to 20-40% central and west. The chance of showers will continue to lower through the evening and overnight hours from west to east tonight as the system pulls away and zonal flow sets in. Zonal flow will continue into Friday for generally dry weather. Weak energy will start to move into western and central zones Friday afternoon and evening, and this will promote a low chance (20-30%) of showers. Temperatures will be cool today with showers around. Look for highs in the upper 40s to lower 50s. Lows tonight will fall into the 30s most locations with a freeze possible over many western locations. NBM has a 60-80% chance of western zones having lows below 32F tonight, with a 10% chance at Billings and a 60% chance at Sheridan. Warmer weather will return for Friday with high temperatures in the 60s. TWH Saturday through Thursday... An upper trough will move across the region Saturday through Sunday, bringing an increased chance for precipitation across the area. See below for a probability table for total precip through Sunday night. >0.10" >0.25" >0.50" --------------------------------------- Livingston 60% 35% 15% Big Timber 65% 45% 20% Red Lodge 70% 50% 25% Billings 60% 40% 20% Hardin 65% 45% 25% Sheridan 65% 45% 25% Forsyth 60% 40% 20% Miles City 50% 30% 15% Broadus 50% 30% 20% Baker 40% 20% 10% On Monday, upper level ridging will build in, bringing dry conditions and warmer temperatures into midweek. By Wednesday afternoon, upper level flow is expected to become southwesterly as the ridge moves out of the region, leading to a more unsettled pattern to end the week. Currently, there is a 20-30% chance for precip Wednesday, increasing to a 30-40% chance Thursday. High temps will be in the mid 60s to low 70s Saturday before dipping slightly Sunday into the 60s. Monday will be the start of the warming trend, with highs in the upper 60s to mid 70s, increasing to upper 70s to mid 80s by Wednesday. Then, as the ridge moves out, highs Thursday will drop back into the 70s. Archer && .AVIATION... Showers across the area, and rain/snow mix near KLVM and KSHR, will affect the region this morning through evening. Low ceilings and pockets of heavy rain will periodically reduce conditions to IFR/LIFR. Expect mountain obscuration. Winds will gust to 30-35 kts this afternoon and evening. Archer && .PRELIMINARY POINT TEMP/POPS... Tdy Fri Sat Sun Mon Tue Wed ------------------------------------------------------- BIL 052 036/065 042/068 047/067 046/075 049/081 053/082 +/T 32/W 15/T 65/T 10/U 00/U 12/T LVM 050 032/062 037/064 041/064 040/073 045/080 050/080 +/T 12/T 16/T 64/R 10/U 01/U 13/T HDN 052 034/067 039/070 045/068 043/076 046/082 051/083 +/T 51/U 13/T 55/T 20/U 00/U 12/T MLS 053 036/065 040/070 046/068 046/075 047/082 053/084 9/T 62/W 11/B 35/T 20/U 00/U 11/U 4BQ 059 037/064 040/069 045/066 046/072 047/081 052/084 9/T 81/U 01/B 35/T 20/U 00/U 01/U BHK 057 035/062 038/068 042/067 044/072 046/078 049/081 9/T 81/B 01/U 25/T 21/U 00/U 01/U SHR 053 031/063 037/066 041/064 040/072 044/079 049/083 +/T 81/U 03/T 66/T 20/U 00/U 01/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Warning remains in effect until midnight MDT tonight FOR ZONES 67-68. Winter Storm Warning in effect until 6 AM MDT Friday FOR ZONE 171. WY...Winter Storm Warning in effect until 6 AM MDT Friday FOR ZONE 198. && $$ weather.gov/billings