139 

FXUS65 KBOI 290018

AFDBOI



Area Forecast Discussion

National Weather Service Boise ID

618 PM MDT Sun Jun 28 2026



.UPDATE...Updated aviation discussion.



&&



.KEY MESSAGES...

- Showers and isolated thunderstorms are expected this 

  afternoon and evening across southwest Idaho.



- Precipitation will persist across the West Central mountains 

  through Monday, with another round of showers returning 

  Tuesday afternoon.



- Warmer and drier conditions Tuesday through Thursday.



&&



.SHORT TERM /Through Tuesday Night/...

Issued 214 PM MDT SUN JUN 28 2026

Scattered showers and isolated thunderstorms will continue this

afternoon and evening, with the main focus across southwest Idaho

as moisture moves in from the north on the back side of the upper

level low. The greatest chance for thunderstorm activity will be

over the higher terrain south of the Snake River Plain during

peak afternoon and evening heating before tapering off tonight.

There is a 30% chance for these light rain showers to reach the

Treasure and Magic Valleys tonight through Monday morning, though

rainfall looks to be minimal. Showers will continue across the 

West Central mountains through Monday, finally coming to an end

Monday night as the parent low moves east into the northern plains.

The central mountains will see additional precipitation totals

between 0.25 and 0.75 inches through Monday. Areas above 7500 feet

could see an additional 1 to 3 inches of snowfall tonight. 



A broad upper level trough remains over the area on Tuesday. 

This persistent large-scale pattern will allow a weak shortwave 

passage to cross the region, triggering another round of showers

across the west central mountains. Temperatures will remain well

below normal, tracking roughly 10 to 15 degrees below seasonal

averages through the short term period under the influence of

the trough.



&&



.LONG TERM /Wednesday through Sunday/...

Issued 214 PM MDT SUN JUN 28 2026

Troughing over the region will support isolated showers and 

thunderstorms across the higher terrain of SW Idaho, and cooler 

than normal conditions through the end of the week. Most guidance

shows this trough deepening just to our west throughout the week.

With flow taking on more of a southwesterly component, 

temperatures will steadily warm. As of now it appears that this

warming trend will be more gradual in eastern Oregon. Come 

Friday, the trough finally looks to progress east of our area. 

This will temporarily hinder the warming trend on Friday, before

a building ridge behind the trough brings temperatures back up 

to near normal. The timely exit of this trough will make way for

a pleasant Fourth of July, with near normal temperatures and 

dry conditions. The pattern evolution becomes more uncertain to 

end the period, although the Grand Ensemble favors continued 

ridging and therefore continued warm and dry conditions.



&&



.AVIATION /00Z Monday through Tuesday/...

Issued 603 PM MDT SUN JUN 28 2026



VFR. Area of light precip spanning across far E Oregon and 

southwest/west-central Idaho this evening, along with isolated 

t-storms near ID-NV border. MVFR/IFR in mtn showers, with light

snow above 7kft MSL. Mtns obscured. Showers continuing Monday,

with reduced lightning threat. Surface winds: SW-NW 5-15 kt. 

Gusts to 15-25 kt through sunset, returning Mon afternoon. Winds

aloft at 10kft MSL: NW 15-25 kt.



KBOI...VFR. Periods of light rain before Mon/09Z. A 20% chance 

of rain showers returning Monday afternoon. Foothills obscured

with SCT-BKN clouds between 5000-7000 ft AGL. Surface winds: NW

10-15 kt with gusts to 20-25 kt through sunset, then variable 

or SE around 5 kt overnight. 



&&



.BOI WATCHES/WARNINGS/ADVISORIES...

ID...None.



OR...None.



&&



$$



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AVIATION.....SH

SHORT TERM...JDS

LONG TERM....NF