Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
978 FXUS65 KPIH 272010 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 210 PM MDT Thu Mar 27 2025 .KEY MESSAGES... - Showers and isolated thunderstorms will accompany passage of a cold front through this evening - Minor flooding impacts remain possible through tonight while temperatures fall, due to low/mid-elevation snowmelt and runoff - Conditions turn cooler and unsettled through the weekend into early next week && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 1252 PM MDT Thu Mar 27 2025 Satellite imagery shows closed low remaining parked off PacNW coast, while vigorous shortwave and attendant surface cold front progressing through Eastern Oregon toward East Idaho this afternoon. Cloud cover has filled in across East Idaho, with weak radar returns beginning to develop across some of the region, largely a reflection of the cloud cover and perhaps some virga but no recorded precipitation reaching the ground as of yet. CAMs still develop line of isolated thunderstorms along frontal boundary as it moves through East Idaho, with showers filling in. CAPE is minimal, but there is enough dynamics coincident with the frontal boundary to support development. Shear and mid level winds support gusts 40-45 mph. The bulk of the threat should end mid evening behind the front and the loss of daytime heating. NBM did not support keeping thunder in the forecast this evening, but added slight chance thunder mention through 9pm. Temperatures begin to fall from recent record levels overnight tonight into Friday, with lingering showers mainly higher elevations. Elevated snow levels fall toward but not completely to all valley floors. Second shortwave rides through the region during the day Friday. Best chance for showers associated with this feature will be across the central and northern mountains, less so across the eastern and southern highlands, but generally expected to be dry within the Snake Plain. Breezy winds are anticipated, along with temperatures some 15 degrees cooler than today, and closer to seasonal normals. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Issued at 1252 PM MDT Thu Mar 27 2025 By Saturday, we`ll be into our active, cooler pattern across all of Eastern Idaho. Highs will be in the 40s and 50s by Saturday afternoon with light, showery precipitation reaching valley floors by Saturday as a shortwave trough moves through Eastern Idaho. Most of this will fall as rain in the valleys and a few isolated storms, though there is a 30 to 40 percent chance of very light snowfall in the upper Snake River Plain early Sunday morning. Snowfall totals throughout Saturday are expected to remain light with less than an inch in the upper Snake River Plain and about 1-4 inches of snow in the mid to upper elevations of our mountain zones. A very weak, transitory ridge passes through on Sunday giving us a brief break in the activity for a portion of the day that will allow our afternoon highs to warm just a couple of degrees. As the next low moves into the PNW, the next wave of moisture arrives on Monday. This brings a bit better moisture transport into Eastern Idaho compared to the showery activity of this weekend. Highs will fall into the 40s for Tuesday and Wednesday and expect breezy conditions each afternoon with wind gusts in the 25 to 35 mph range, at least. Models still remain quite divergent with solutions for another system moving ashore in the middle of next week. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1127 AM MDT Thu Mar 27 2025 VFR conditions are expected through the beginning of the afternoon at all sites with the potential for a shower or thunderstorm increasing after 22Z as a cold front moves through the area from west to east. MVFR CIGs and/or VIS are likely as the cold front brings showers/storms through each terminal with the HREF 24-hour thunder probability showing a blanket 10 to 30 percent chance at all sites this evening/tonight. The exact arrival times will vary a bit, but 02-06Z is the most likely timing for the front to pass through BYI, PIH, and IDA with the activity becoming more linear through PIH, IDA, and DIJ. Winds will be gusty and erratic near storms. There is about a 20 to 30 percent chance that rain mixes with/to snow at DIJ this evening which could further impact VIS as precipitation moves through the area. Precipitation chances on Friday look to be more showery. && .HYDROLOGY... Issued at 1252 PM MDT Thu Mar 27 2025 Cold frontal passage this afternoon/evening will allow for colder more seasonal temperatures to return to East Idaho. However, there could be delayed runoff due to the warm temperatures from today. Therefore continued the Hydrologic Outlook for one more cycle. Silver Creek near Picabo continues to fluctuate near the lower end of Action Stage, and the Portneuf River is now expected to remain below any threat levels for this warmth cycle. Melt is expected to slow significantly this weekend as temperatures return to seasonal normals, especially with respect to overnight lows. Precipitation could add to runoff concerns, but impacts will likely be localized. && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...DMH LONG TERM...AMM AVIATION...AMM HYDROLOGY...DMH