Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 172034

Area Forecast Discussion
National Weather Service Boise ID
234 PM MDT Tue Oct 17 2017

.SHORT TERM...Tonight through Thursday...Mild dry weather will
continue through Thursday. Temperatures are expected to be 5 to 10
degrees above normal. A weak shortwave trough embedded in strong
westerly flow aloft centered along the Canadian border will cross
the Continental Divide this evening. Other than high clouds, and a
few showers mainly north of Baker and McCall tonight, the trough
will have little effect on our area. The upper level flow will back
into the southwest Wednesday and Thursday ahead of a Pacific cold
front. This pattern will advect warmer air over our area. The amount
of warming in the valleys will depend on how much the overnight
temperature inversions mix out during the afternoons. For tomorrow
and Thursday, models show less cloud cover than today, as well as
stronger mid level winds, which will favor mixing the warmer air
down to the surface.

.LONG TERM...A cold front associated with an approaching trough will
move through the forecast area Thursday night through Friday
morning. Showers are expected with and behind this frontal passage,
along with a decrease of around 20 degrees in temperatures between
Thursday afternoon and Friday afternoon. With this colder air, snow
levels will drop to around 4500 ft over the mountains, with snowfall
anticipated. A secondary push of moisture will then move over the
area during the weekend, keeping rain and snow possible across the
area with temperatures remaining 5 to 10 degrees below normal.
Drying conditions and warming temperatures look to develop over the
area beginning Monday afternoon with a building ridge.


.AVIATION...VFR. Zonal flow expected across the area with dry
conditions. Surface winds: Variable direction, generally less than
10 kts. Wind may increase to around 15 kts after 18z Wednesday,
mainly across eastern Oregon and the potentially into KMYL in Idaho.
Winds aloft at 10kft MSL: West 20 to 30 kts.





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