Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 131619

Area Forecast Discussion
National Weather Service Pocatello ID
1019 AM MDT Sun Aug 13 2017


Been watching the HRRR runs along with the 12z NAM and GFS for
convective potential across the central mountains this afternoon,
and it does not look encouraging. Trends seem to indicate the band
of rain moving out of Oregon will remain fairly stable. Can`t rule
out a few isolated strikes up there, but certainly much less
coverage than anticipated. Therefore, we are canceling the red
flag warning.



.PREV DISCUSSION... /issued 314 AM MDT Sun Aug 13 2017/

SHORT TERM...Today through Monday. Widely scattered showers/tstms
across the southern highlands early this morning will diminish
later this morning. A strong upper trof will move into the Pac
NW today...and an an associated cold front will move into the
central mtns this aftn. Scattered showers and tstms will develop
across the central mtns this aftn and become more widespread this
eve as the front slowly advances southeastward. Models not showing
much not expecting too much tstm activity.
Showers/tstms increase across the rest of the fcst area on Mon as
the cold front advances...and a secondary upper trof moves thru.
Precip tapers off Mon night as the upper trof moves east. Temps
will be several degrees cooler on Mon.

LONG TERM...Tuesday through Sunday. Showers linger along the WY
border and the divide on Tue...but northwest flow aloft eventually
dries everything off by late Tue. The rest of the fcst period
looks dry with gradually warming temps.


AVIATION...Isold showers/tstms remain possible this morning.
Showers/tstms become more numerous over the central mtns this aftn
with the approach of a cold front...and in the Snake River Plain
toward Mon morn. Cigs expected to remain VFR...but near the low
end tonight at KSUN and KDIJ. Hedges

FIRE WEATHER...A seasonally strong trough approaching the area from
the Pacific Northwest will drive a strong cold front through the
area tonight and Monday morning, bringing with it fire weather
concerns. First, a Red Flag Warning continues for Fire Weather Zones
422 475 and 476 through this evening due to the potential for
scattered thunderstorms across these areas ahead of the cold front
this afternoon and early evening. Another area of concern will be
across fire weather zones 425 and 410 as southwest to westerly wind
gusts will increase ahead of the cold front, with gusts to around 30
mph developing around 3 PM across the Arco Desert, continuing to
around 9 PM. Minimum relative humidity values today were lower than
even the driest forecast model, so have leaned even drier than most
guidance. This takes minimum relative humidity values down near
critical values around 15 percent. This will create near critical
fire weather conditions. Due to the marginally low relative humidity
values, will hold off on Red Flag issuance at this time. Isolated to
widely scattered thunderstorms possible across the Caribou Highlands
northward along the Wyoming border this afternoon and evening as
well. Anticipate a band of potentially wetting rains to develop
behind the cold front across the Salmon-Challis/Central Mountains
towards midnight, sliding across the Snake Plain overnight. Some
thunderstorm potential with this boundary as well, however think
coverage will remain isolated. Gusty winds possible behind the cold
front, particularly across Fire Weather Zones 427 and 425 this
evening through early morning Monday.

Significantly cooler conditions expected Monday across the area with
relatively moist humidity values. However, expect a quick drying
trend Tuesday, with critically low relative humidity values and
marginally strong winds across the Snake Plain Wed-next weekend as
dry westerly flow takes hold of the region. AD/Hedges



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