Sunrise 6:35 AM   Sunset 8:35 PM Moonrise 12:00 AM   Moonset 7:24 AM

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FXUS65 KPIH 261942 AFDPIH

Area Forecast Discussion National Weather Service Pocatello ID 142 PM MDT Fri Apr 26 2024

SHORT TERM
Tonight and Saturday Afternoon satellite imagery shows widespread cloud cover across the region with a few showers having developed recently around Craters of the Moon and into the central mountains. Hi-res CAMs show this as the primary area of precip for the remainder of the afternoon and into the evening. Could get a few thunderstorms developing as well but the environment is only marginally favorable. Can't rule out some precip sneaking into the valleys but they'll probably stay mostly dry through midnight. This will change as we get into the overnight hours and into Saturday morning however. CAMs are basically in unanimous agreement that as the upper low to our west moves south into Utah overnight, wraparound moisture will move from east to west across the area. Saturday certainly looks wet region- wide. Temperatures are on the cooler side of normal today with clouds and precip in the area and will be again tomorrow. That being said, snow levels will be high the next few days (around 8000 ft) so any accumulation will be limited to the highest terrain but with ample QPF expected over the days ahead, some decent backcountry accumulations are expected. This is especially true in the Lost River, Lemhi and Beaverhead Ranges. The QPF forecast hasn't changed much with 1/4 - 1/2" of rain likely in the lower elevations through Saturday night with higher amounts possible into the mountains, especially in the higher elevations.

In addition to the precip, winds will get breezier tomorrow especially into the Magic Valley, South Hills and up towards Shoshone. Looks to remain near, but just below, Wind Advisory levels so that translates to winds in the 20-30 mph range with some gusts to around 40 possible at times. McKaughan

LONG TERM
Sun through next Fri night The Sat night trough finishes up on Sun/Sun night, with the main precipitation during this period in the eastern highlands from MT to UT, and most of this Sun during the day. This includes a risk of thunderstorms in that highland region. But very quickly on Mon the closed low from which that trough ejected moves onshore and moves into the ID Panhandle. This sets up a classic wind event with plenty of precipitation. At this time of year, could be enhanced by convection in thunderstorms. Very strong wind aloft also suggests at least a Wind Advisory, and potential for more. It mostly affects the central mountain ridges, the eastern Magic Valley, and the lower Snake River plain, and valleys of the southern hills region. There is a brief break Tue, and the another closed low moves into the southern Panhandle on Wed to bring more wind and some precipitation, although not as heavy this time.

There is not a third trough, so there is a longer period of cold northerly flow after this low passes beyond the northern Rockies.
However, the clear skies of the upper level ridge also arrive, and the result is still some warming despite the northerly air flow.
By Thu temperatures should be mainly 63 to 73 in the heavily populated valleys, and 50s to lower 60s for the mountains and northern highlands.

For the rest of the period, the upper level ridge axis stays to the west, providing a dry, cold air flow that will prevent a strong warm up and keep skies clear. The only area at risk would be the extreme northeast corner of the upper Snake Highlands.
Messick

AVIATION
TSRA/SHRA will make the afternoon lively with the main issue outflow boundaries messing up winds temporarily. Conditions worsen late tonight for KBYI, KPIH, KIDA, and KDIJ as a low meanders into southern UT. This brings northerly to northeasterly wind which does provide some upslope flow and reduces CIG mainly, but possibly as well VSBY, to marginal VFR conditions, with a risk of IFR in KPIH and KIDA. Meanwhile, KSUN will have to deal with TSRA this afternoon and evening; in fact the risk is higher there than anywhere else.
However, the northerly flow will allow some clearing skies, rather than the clouding up expected elsewhere. Messick

HYDROLOGY
Water levels remain elevated on the Portneuf River from Pocatello to Chesterfield Reservoir where River Flood Warnings remain in effect until further notice. Minor to moderate flooding is expected or ongoing in these areas with both locations forecast to crest this weekend before dropping slightly heading into early next week.
Further north and west along the Snake River, water managers have increased releases from upstream reservoirs leading to high flows in excess of 10,000 cfs downstream from Palisades to Milner. The Snake River near Heise and Snake River at Lorenzo gauges have also reached action stage and are forecast to be at that stage until further notice due to releases from Palisades. Willow Creek below Tex Creek above Ririe Reservoir and the Blackfoot River above Blackfoot Reservoir both also continue to be in action stage since Monday with no major impacts seen elsewhere in our CWA as of Friday afternoon.
MacKay

PIH WATCHES/WARNINGS/ADVISORIES
None.

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