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 19
FXUS65 KPIH 060515

Area Forecast Discussion
National Weather Service Pocatello ID
1015 PM MST Mon Dec 5 2016


Minor update to forecast for tonight, mainly affecting low temps
around Pocatello, Burley, Sun Valley, and Stanley where temps are
falling faster than expected. This is likely due to a slower
progression of cloud cover across the area. Temps are holding up
for now across the upper snake plain where winds are still up, but
will probably fall quickly in the next couple hours when winds let



.PREV DISCUSSION... /issued 149 PM MST Mon Dec 5 2016/

SHORT TERM...Tonight through Wednesday night. Very cold
temperatures the immediate concern in the forecast. Clearing skies
with pockets of stratus likely to limit overall plummet after
sunset. However, based on temps this morning have lowered expected
mins for tonight most areas by several degrees. Winds much less of
a concern. Have a few isolated pockets of wind chill around -20F,
but not enough to be overly concerned with. Will instead highlight
cold temps with social media. Shortwave dropping through PacNW
tomorrow has slowed, and GFS/NAM still struggling on details with
placement and timing of moisture. Have trended precip related
grids slower, still keeping highest potential in areas of
orographic influence across central mtns, gradually shifting to
southeast highlands late Tue into Tue night. QPF amounts quite low
but continued cold temps and higher snow ratios can still lead to
some accumulation. Most locations less than an inch Tue-Tue night
but a few higher elevation areas in the central mtns could see a
few inches - all amounts below general impact levels. Shortwave
axis passes Tue night with all precip shifting out of the region
for remainder of the period. Temps remain cold through the
remainder of the short term. Best potential for windchill impacts
appear to be Wednesday morning behind departing shortwave, when
overnight lows may be slightly colder and winds may be a tad
higher than tonight. DMH

LONG TERM...Thursday through next Monday.  Well, so much for the
models being almost in lock-step with each other.  The GFS is
sticking to its guns with a quicker onset of precipitation Thursday,
then hammering the area pretty hard Thursday night and Friday
although it`s cut back on precipitation over most of the Snake
Plain. However, now it has another surge coming quickly into eastern
Idaho Friday night and Saturday again hitting the mountains pretty
hard. It still dries out the Snake Plain as previously shown, but
now keep more snow showers for the mountains all the way through
into next week. Comparing that to the ECMWF, it really wants to wimp
wimp out on Friday, but really hits the area now Friday night and
Saturday. When looking at this type of pattern, it does appear that
there is plenty of moisture coming off the Pacific and aimed at
Idaho. The issue with this pattern type is TIMING with these
moisture surges, which is always problematic at 4+ days out. For
now, we keep with a good chance of precipitation Thursday night and
Friday. We did trim back amounts across a good chunk of the Plain
based on the current trend. The models are really warming things up
with this storm which is expected, however we aren`t getting a good
vibe on if it`s too quick or not. For some of the more
sheltered/colder valleys, it likely is at this point. For the Snake
Plain, probably not especially along the I-84/86 corridor due to
strong winds/downsloping. We did increase chances for Saturday but
not too drastically for now. The pattern should stay "WARMER" no
matter how things shake out after Friday. It appears snow at night
would be the norm, with at least a mix on occasion at lowest
elevations during the day. Keyes

AVIATION...Dry conditions will continue through most of tonight.
We`ve had some low clouds hang around or redevelop at the valley
TAF sites and KDIJ. There MIGHT be a shower or two in there but
there isn`t any confidence to include VCSH at those airports. It
has been breezy on occasion but the winds are slowly winding down.
With cold air in place and fresh snow, temperatures are likely to
plummet in many areas before clouds move back in. With lighter
winds, there is potential for fog and/or low clouds to form before
sunrise. That is included/carried over in the latest TAFS with
MVFR/IFR conditions if that indeed happens. We have another storm
system moving in tomorrow. Clouds overall will increase, with the
likelihood of any fog going around as that happens. However, the
chance of light snow goes up especially in the mountains. For
KSUN, we included VCSH starting around 9-11z. The storm isn`t
moving very fast so it will take the rest of the day to see any
snow for KBYI, KPIH, KIDA and KDIJ. If/when that happens on
station, MVFR/IFR weather is likely. No real wind tomorrow is on
tap so blowing snow will not be an issue. Keyes



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