Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 290230

Area Forecast Discussion
National Weather Service Boise ID
830 PM MDT SAT MAY 28 2016

.DISCUSSION...No changes from afternoon forecast.  Warmer Sunday,
cold front Sunday night, breezy and cooler Monday, then strong
warming Tuesday through Friday as an upper ridge amplifies over the
Intermountain region.  Late next week should easily be the hottest
so far this year.


.AVIATION...VFR. Mostly clear. Surface winds: west to northwest
5-15kts this evening and Sun afternoon, 10kt or less overnight.
Isolated thunderstorms over the west central Idaho mountains and
southern Twin Falls County Sunday afternoon. Winds aloft at 10K feet
MSL: W to NW 10-20kt.

Monday: Mostly clear, with surface winds becoming NW 10-20kt Monday
afternoon with gusts to 25kt in the Magic Valley.


SHORT TERM...Tonight through Monday...A closed low over southwest
Canada will move east through Monday and bring an upper level trough
Sunday afternoon and evening, and a surface cold front Sunday night.
This system will help showers and thunderstorms develop mainly
across the north - but also in the far southeast corner of the CWA -
Sunday afternoon and evening. We will remain dry tonight and then
dry out again late Sunday night through Monday. We will see a
considerable warmup Sunday in advance of the cold front, with temps
into the lower 80s in the Treasure Valley. On Monday, behind the
cold front, temps will fall 5 to 8 degrees compared to Sunday.
Overnight lows will be near normal.

LONG TERM...Monday night through Saturday...A very warm upper
level ridge with axis over the west coast on Monday night shifts
slowly inland over the Intermountain Region Wednesday and
Thursday. Warm dry west-northwest flow aloft and subsidence east
of the ridge axis will keep skies mostly clear through Wednesday,
with temperatures rising 5 to 10 degrees each day. Highs are
expected to be around 15 degrees above normal on Thursday. By
Thursday afternoon models have the ridge axis slightly east of our
area, with the upper level flow shifting into the southwest.
Although the Southwest Monsoon is still about a month away, models
do show increasing precipitable water over California. Some of
this moisture could be carried north over southeast Oregon and
southwest Idaho by Thursday afternoon. So with marginal
instability and reachable convective temperatures, we are
including a slight chance of afternoon and evening thunderstorms
for southeast Oregon and the west central Idaho mountains.

Thursday night through Saturday...Ridge axis still impacting the
area allowing for above normal temperatures and mostly dry
conditions. Friday morning the models indicate a little bit of
moisture pushing on from the southwest which may cause some light
precipitation for the mountains in southeast Oregon and southwest
Idaho. Some slight instability could lead to isolated
thunderstorms for the afternoon hours. The 12Z ECMWF shows less of
a flattening of the ridge axis Friday. This means temperatures are
likely to remain in the low to mid 90s through the end of the





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