Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 010236

Area Forecast Discussion
National Weather Service Boise ID
836 PM MDT TUE MAY 31 2016

.DISCUSSION...8-10 degs warmer Wednesday as upper ridge builds in the
Great Basin.  Surface cold front, currently off the NW coast, and
upper trough will slide across our nrn zones Thursday bringing
several degs cooling there but little if any cooling in srn zones.
Warming again the rest of the week, possibly to record highs Sunday.
High-based thunderstorms possible late Sunday on the Oregon side. No


.AVIATION...VFR. Mostly high clouds with some mid-level ceilings
moving into eastern Oregon later Wednesday afternoon. Surface winds
mostly light and variable. Winds aloft up to 10K feet MSL, southwest
to west 15-25kts.


SHORT TERM...Tonight through Thursday...Heat builds on Wednesday
warming temperatures 8-10 degrees from today`s highs. Moisture and a
weak disturbance embedded in the flow will deliver a slight chance
afternoon showers and thunderstorms in the mountains of east-central
Oregon, north and west of Baker City, and the west-central Idaho
mountains north of McCall. A trailing short wave trough on Thursday
flattens the flow aloft and pushes a weak front into the region. The
result will be greater cloud cover and slightly cooler temperatures
(about 5 degrees) north of the front, which stalls across southern
Harney and Malheur counties and lower Snake River Plain. Areas south
of the front, including the Western Magic Valley, will see little
change in conditions on Thursday.

LONG TERM...Thursday night through Tuesday...A strong upper level
ridge over the Intermountain Region will keep temperatures 10 to 20
degrees above normal. The ridge will reach its peak amplitude on
Saturday, but Sunday is expected to be the warmest day, as the
surface thermal trough centers on our area, and record highs are
possible. The ridge will lose much of its amplitude Monday and
Tuesday as a weak upper level trough from off the central California
coast moves over Nevada. The trough will bring increasing moisture,
but time-height cross sections show that it will stay above 400 mb
through the weekend, too high for convective development. Mid-level
moisture does not appear over our area until Sunday evening at the
earliest. Both the GFS and ECMWF show modest CAPE over the higher
terrain starting late Sunday, but buffer soundings indicate any
thunderstorms will be high-based. So chances of measurable
precipitation will be low.





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