Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 042029

Area Forecast Discussion
National Weather Service Missoula MT
229 PM MDT MON MAY 4 2015

.DISCUSSION...The atmosphere will become unstable enough to cause
isolated to scattered thunderstorms across Lemhi county up into
the Butte/Blackfoot region this afternoon and evening. These
thunderstorms will be capable of causing gusty and erratic winds
with very light rainfall. This convection will diminish after

The models are indicating a very weak disturbance moving up into
Clearwater county Idaho later this evening. Then track through
northwest Montana. This disturbance could cause a few showers to
be generated. The cloud cover associated with this feature should
keep minimum temperatures warmer compared to last night.

A weak cold front will swing through the Northern Rockies on
Tuesday. This front will have minimal moisture to work with so
showers should be fairly limited. The best location for shower and
thunderstorm development appears to be across Lemhi county up
into the Butte/Blackfoot region once again. The convection should
be more numerous compared to today. The region should expected
breezy conditions post frontal. The upper level winds do not
appear to be that strong, so these winds will be primarily
pressure gradient driven.

A trough will encompass the majority of the western U.S. Wednesday
through Friday, resulting in an unsettled, cooler pattern for the
Northern Rockies. Seeing as how deep this trough becomes with time
amongst forecast models, the bulk of potential rainfall may remain
focused over Butte, the southern Bitterroot valley, the southern
portion of the Clearwater Mountains, and south into the Salmon
river valley. These locations will see the most prolonged
precipitation, though rainfall totals from Wednesday through
Friday should only amount to between 0.25 inches and 0.50 inches.
Elsewhere across the region, amounts should equal less than 0.25

For those interested in the weekend: as of now, it appears that
Saturday and Sunday could be on the drier side, but will
ultimately depend on how quickly the low pressure trough exits to
the east. Stay tuned!


Today will be the last day of relatively benign, fair conditions
for the terminals. Winds will generally be light with slight
breeziness for the afternoons. Expect an increase in high cloud
cover by this afternoon/evening ahead of the next weather system
beginning early Tuesday. A weak cold front will swing through the
region on Tuesday with breezy conditions post frontal. The best
instability and moisture will be across Lemhi county and southwest
Montana, so KBTM and KSMN could be impacted by thunderstorms.



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