657 FXUS65 KMSO 262039 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 239 PM MDT Mon Jun 26 2017 ...STRONG STORMS LIKELY THIS EVENING, PRODUCING STRONG WINDS, HAIL, HEAVY DOWNPOURS... .DISCUSSION...A very hot and dry day today will transition to a convectively active evening for north central Idaho and western Montana. Severe storms are already firing off across northeast Oregon, and these storms will cross into central Idaho later this afternoon, continuing through the evening as they work their way eastward into Montana. ***The greatest thunderstorm threat for central Idaho regarding thunderstorms will be strong outflow winds in excess of 40+ mph and hail (in addition to lightning/brief heavy downpours). The strongest storms will likely occur between the hours of 4pm-8pm PDT.*** For western Montana, a band of weak showers is currently crossing NW Montana at this hour (2:30 pm MDT), and should produce nothing more than a light passing shower. Warm and dry conditions will persist across most of western MT until the thunderstorms form later this evening, likely after 6 pm MDT. ***The greatest thunderstorm threat for western Montana will be strong outflow winds in excess of 40+ mph, abundant lightning, and brief heavy downpours. Small hail may also be possible (but will be a greater threat for ID locations). The strongest storms are likely to occur between 7pm-10pm MDT.*** Rain showers are possible during the AM hours Tuesday for the Northern Rockies, as the system that caused thunderstorms overnight slowly progresses east. The afternoon will be breezy in the wake of the exiting system, with cooler air and temperatures 10 or so degrees cooler than Monday, with highs near seasonal averages. Wednesday will also be breezy, as the region remains under northwest flow aloft. Seasonal temperatures continue throughout the week, with Thursday and Friday bringing a slight chance for additional afternoon showers along the Continental Divide. Valleys not along the Continental Divide look to remain dry into the weekend. Models hint at a shortwave trough moving through Saturday, which would bring the potential for enhanced rain chances, but confidence is low at this point, given differing model solutions and a lack of consistency with previous runs. Regardless, this time period will be watched closely given the upcoming holiday weekend. && .AVIATION...Strong thunderstorms will occur tonight for all terminals, impacting KGIC around 26/2300Z, KMSO by 27/0300Z and both KGPI and KBTM around 27/0500Z and thereafter. Gusty erratic outflow winds will be the dominant aviation threat, along with abundant lightning, small hail, and brief heavy downpours which could quickly reduce visibility. Showers and embedded thunder should continue overnight through Tuesday morning, with conditions remaining showery but improving overall after 27/2200Z. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$ |