Area Forecast Discussion
Issued by NWS Boise, ID
FXUS65 KBOI 310233
Area Forecast Discussion
National Weather Service Boise ID
833 PM MDT SAT JUL 30 2016
.DISCUSSION...Showers and thunderstorms were moving ENE at 25 mph
across extreme southern portions of the CWA - generally south of a
line from Rome, Oregon to Twin Falls, Idaho. These will weaken
through midnight before dissipating. Owing to very dry low-level
air, these showers and storms still have the potential to produce
wind gusts to 40 mph. The red flag warning will remain in effect.
A weak dry cold front will move through overnight and Sunday
morning, bringing slightly cooler air to the region. High
temperatures tomorrow will be near normal. The forecast is on
track and no changes are anticipated at this time.
.AVIATION...VFR. Isolated thunderstorms until 06Z south of a KREO-
KTWF line. Skies becoming mostly clear with a few mid-level clouds
along the Nevada border. Smoke layers with MVFR visibilities will
continue in the Lowman area and surrounding valleys. Expect smoke
to filter into the Snake River Plain by Sunday morning with local
MVFR visibilities through 18Z. Surface winds becoming 10 knots or
less after sunset, gusty winds to near 30 knots near thunderstorms.
Winds aloft westerly 15-25 knots up through 10K feet MSL.
Outlook for Sunday...Mainly VFR. Smoke will continue in the Boise
mountains, filtering into the Snake River Plain again Sunday night
and Monday morning. Otherwise mostly clear skies with breezy
west to northwest surface winds.
SHORT TERM...Tonight through Monday...Scattered thunderstorms are
expected from late this afternoon through the early evening hours
in southern Idaho mainly south of the Snake River. The boundary
layer remains quite dry and not much rain is expected to reach the
ground with this convective activity. Expect gusty surface winds
in the vicinity of thunderstorms. A dry cold front will move from
west to east through the area late tonight. Expect breezy
northwest winds and a 7 or 8 degree drop in temperatures behind
the front on Sunday. This will still be seasonably hot as we are
at the climatological warmest time of the year. Temperatures will
once again climb to about 5 degrees above normal on Monday under
LONG TERM...Monday night through Thursday...Breezy conditions
through Wednesday as an upper-level closed low transitions across
the Pacific Northwest. Two dry cold fronts associated with the
pattern are expected to move through the region sequentially. The
first will come Monday night and the second Tuesday for decreasing
temperatures each day, reaching about 7 to 10 degrees below the
seasonal normal Wednesday /10 to 15 degrees below Monday`s high/.
Upper level flow will be out of the southwest at first, but will
turn to the northwest by Tuesday night as the trough axis passes
through the region. A developing trough along the Pacific coast
will put the region back under a southwest flow Thursday, allowing
temperatures to rise to about normal.
Thursday night through Saturday...Models are in fairly good
agreement in showing an upper low in British Columbia Friday as well
as some monsoonal moisture pushing up north, however they differ on
how these two features will progress. GFS wants to bring some
monsoonal moisture into Southern Twin Falls County Friday night and
keep the upper low further north while the ECMWF brings the low
further south and keeps the monsoonal moisture out of the area.
Confidence is low at this time because of this disagreement so left
forecast dry for now. Temperatures hover right around normal for
this time period.
ID...Red Flag Warning until midnight MDT tonight IDZ423-426.
PREV SHORT TERM...JB
PREV LONG TERM....AB/JC