Local Forecast Discussion
000 FXUS65 KPIH 181938 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 138 PM MDT Mon Jun 18 2018 .DISCUSSION...A low pressure system over southwestern Idaho will track into southwestern Montana by Tuesday morning. Satellite and radar imagery pretty well highlight the circular fashion of showers and thunderstorms around this disturbance. A Flood Watch remains in effect for the Custer County area and the Upper Snake Highlands, including Spencer, Island Park, and Driggs until midnight tonight. The trend is towards less forecast rainfall the next 24-36 hours. A few areas may see an additional half inch of rain. Portions of the Central Mountains and Upper Snake Highlands have received over two inches of rain with localized amounts around three inches over the. past 72 hours. Wednesday afternoon scattered showers will linger over the northern mountain areas while a transitory high pressure ridge moves quickly through. Models are still having trouble with this weak flow pattern. The latest GFS run brings a disturbance through central Idaho and and Monida Pass to Island Park Thursday night and Friday. This is followed quickly by another disturbance on Saturday. The odd part is some of this activity was in the models a couple days back, then disappeared and reappeared. The consensus looks to be that the storm track will be across the northern half of Idaho, close enough for showers in our area. For now, made few changes to the extended to try an time these events. RS && .AVIATION...With the low still in place, several rounds of showers and thunderstorms will persist, although we COULD see a potential break overnight in many places. That is IF the high resolution models are correct. Even if there is a break, it appears with the amount of moisture around low clouds are possible. The general pattern is still in play: VFR weather is the norm. We could see MVFR/IFR ceilings or visibility with either heavier showers/storms AND low clouds/patchy fog where any breaks in rainfall occur. The latter scenario will be confined to tonight and Tuesday morning. Keyes && .FIRE WEATHER...The persistent low will finally begin a slow exit tomorrow and Wednesday. Until then, multiple rounds of showers and thunderstorms will continue with locally heavy rainfall possible. Even with the ridge building in for Wednesday, look for showers and isolated thunderstorms across Zones 422, 475 and 476. Similar conditions for Zone 411 and the eastern half of Zones 410 and 413. These storms will have wetting rains but nothing like what has been experienced since late last week. By Thursday and Friday, another storm drops across the Panhandle and into Wyoming. This will be bring yet another round of rain and isolated thunderstorms generally the same locations. By the weekend, the potential forecast based on the models is 180 from each other. One has dry and warmer with a ridge developing. The other brings another closed low and more precipitation our way. We went with showers and isolated thunderstorms possible for all mountain fire zones, but gradually decreasing overall. If we indeed get the drier pattern to stick around, we would end up with a lower humidity/breezy Friday across most of central and eastern Idaho with gusts 25-35mph currently in the forecast. Keyes && .PIH WATCHES/WARNINGS/ADVISORIES... Flood Watch until midnight MDT tonight for IDZ018-019-032. && $$
NWS PIH Office Area Forecast Discussion