Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 092117

Area Forecast Discussion
National Weather Service Missoula MT
317 PM MDT Wed Jul 9 2014


A weak upper-level trough and area of monsoonal moisture has
pushed through Oregon today, and is approaching Central ID and SW
Montana early this afternoon. So far, convection has been weak
with only a few radar returns and virtually no lightning
reported. If anything can get going later this afternoon over SW
Montana and especially Lemhi County ID, gusty winds would be the
main threat.

Mostly benign weather with continued hot temperatures is expected
through the rest of the work week and into the weekend. The
exception to the quiet weather will be a daily slight chance of
showers and maybe a thunderstorm over mountains of SW Montana
southward through Lemhi County MT. A lack of upper- level
disturbances and drier air will keep chances limited.

Thursday night into Friday, a very weak backdoor front looks to
move through Glacier NP and vicinity. This will bring some east
winds at times and a cooler start to the day Friday. Otherwise,
no impacts are expected.

An upper-level ridge will build over the area through the
weekend. By Sunday, the ridge axis looks to be parked over
Western MT, likely bringing the warmest temperatures of the
foreseeable future. Current guidance shows Western MT valley
temperatures reaching the mid to upper 90s, with 90s and low 100s
in Central ID valleys.

Next Monday through Wednesday...There appears to be a large scale
trend towards a slight upper-level ridge break-down with easterly
winds developing at across the area. There are differences in how
the GFS and ECMWF weather models are handling smaller wave
features, so opted to go middle of the road with climatology for
precipitation. Forecast confidence is average for precipitation,
but below average for temperatures. With the easterly winds
developing on Monday and not much change to temperatures aloft, a
few places across central Idaho into western Montana may actually
see warmer temperatures than forecast with the additional
downsloping and milder temperatures at night. Also, if the cooler
air east of the Continental Divide is able to make it into
western Montana Tuesday then cooler temperatures than forecast
would occur. Either way, the bottom line is a change towards
cooler and wetter conditions is possible next week.


.AVIATION...Showers and a few embedded thunderstorms are still possible
for terminals KSMN and KBTM this afternoon and evening. KSMN and
surrounding Lemhi County could see a few thunderstorms capable of
outflow winds as high as 45 kt between 07/2100z and 08/0200z.
KBTM could see a few passing showers between 07/2200z and
08/0300z with erratic winds. This wave will move on through late
this evening, so expecting clearing skies overnight.




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