Area Forecast Discussion
Issued by NWS Pocatello, ID

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
FXUS65 KPIH 121935

Area Forecast Discussion
National Weather Service Pocatello ID
135 PM MDT Sat Aug 12 2017

.DISCUSSION...Watching limited convection across the region this
afternoon. All in all, atmosphere is relatively stable with a
shortwave ridge overhead. We are seeing a few terrain-driven
storms develop which may persist into the evening. Otherwise,
we`re awaiting the next cold front which will move into the
central Idaho mountains late Sunday afternoon. Ahead of the front
we may see a few showers or thunderstorms develop as moisture
streams into the region late tonight into Sunday morning. However,
the main batch of showers and thunderstorms will accompany the
front. GFS/NAM differ significantly Sunday night into Monday in
handling convection across the region as the front slides into the
area. GFS has been more consistent in showing widespread rain
with embedded thunder slide southeast through the central Idaho
mountains into the Snake Plain and Magic Valley Sunday Night.
Then, expecting redevelopment on Monday over east Idaho as the
front continues to march across the area. GFS is showing some
lingering moisture possible on Tuesday across the eastern high
country, otherwise looks fairly dry for the remainder of the week.
Temp forecast for Monday is especially tough because of the
impact of rain/clouds on the region. Potentially, may not see
highs get above 70 in the Magic Valley and Snake Plain.



.AVIATION...Another chance for thunderstorms this evenings,
particularly at DIJ and SUN. A better chance for thunderstorms look
to occur at SUN Sunday afternoon, which will require a increased
wind forecast. For now, a slight increase is noted. VFR skies will
persist. NP/Valle


.AIR STAGNATION...Air quality will remain degraded across Custer and
Blaine counties due to wildfire smoke today. Winds are expected to
increase in these areas Sunday which should help move the smoke to
the east and/or southeast. Increasing precipitation in these areas
should also help alleviate the poor air quality. NP/Valle


.FIRE WEATHER...There are several fire concerns over the next 48
hours to speak of. The first begins this evening due to potential
thunderstorm activity across the Central Mountains and Upper Snake
Highlands. Activity is expected to be isolated in nature and we will
not issue a Red Flag Warning as a result. Through the overnight
hours, additional thunderstorms are possible across zone 476.

For Sunday, increasing RH values are anticipated with more northerly
air coming through the area. Westerly flow will be noted at the
surface especially in the Snake Plain. Wind gusts will easily exceed
25 mph across 422, 476 and 475 Sunday afternoon and evening.
Scattered thunderstorm coverage is anticipated early in the
afternoon hours across 422, 476 and 475 which will persist through
the evening. Gusty outflow winds are likely. ERC`s in this area are
high. As a result, a Red Flag Warning has been issued as a result.
Wind speeds are forecast to reach 30+mph across zones 410 and 425
but not exceed the majority of the zone, therefore, this in
combination of only near critical RH values, we will not issue a Red
Flag at this time. The progression of the thunderstorms through the
remainder of SE Idaho is uncertain attm, and forecast models are
having differing views on this. We are following more in line with
GFS`s solution as opposed to the NAM, who develops the line of
storms in the overnight hours Sunday into Monday morning. Of course,
this will bear watching.

Mondays forecast with initially be dependent on how Sundays line
of thunderstorms progresses but then should clear out late.
Warming and drier conditions are forecast for Tuesday onward with
minimal chances for thunderstorms. NP/Valle


Red Flag Warning from noon Sunday to midnight MDT Sunday night
for IDZ422-475-476.


$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.