935 
FXUS65 KPIH 070905
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
305 AM MDT Wed Oct 7 2020

.DISCUSSION...
Above normal high temperatures to continue across the area today and 
through Saturday as high pressure remains in control of the weather 
across eastern Idaho. Afternoon highs the next few days will top out 
in the upper 70s to lower 80s. High pressure will keep the region 
dry as well through Friday. SW flow aloft for the next few days will 
likely bring smoke/haze back to the area. This shouldn't have too 
much of an impact on our sensible weather but it will be noticeable 
nevertheless. Overnight lows will still be cool overnight especially 
across the upper Snake Plain and the Arco Desert. Some patchy frost 
will be possible with light winds overnight but dewpoint depressions 
are a bit high for widespread frost formation so no plans for an 
advisory at this time. 

Things change drastically as we move into the weekend as a major 
pattern change is on the horizon as upper-level trough and area of 
low pressure dig into the Pacific NW. This will bring widespread 
precip, including high elevation snow, gusty winds and much colder 
air to eastern Idaho as we move into Sunday and the early next week. 
Models have trended a touch colder on Sunday with snow levels now 
around 5500 feet in the Central Mountains and in the 6000-7000 ft 
range elsewhere. It will certainly be a drastic difference compared 
to what we've seen thus far in a rather warm October. High temps in 
the 40s and 50s can be expected Sunday and again on Monday. After 
Monday, it appears that temps will begin to moderate, albeit slowly, 
as we move into the middle part of next week with limited precip as 
weak high pressure attempts to build back in. McKaughan 


&&

.AVIATION...
We are still looking at VFR conditions, with the caveat that 
smoke will be increasing from the south and west today. At the 
moment, we aren't thinking that visibility will drop to MVFR 
unless more local fires flare up or light off. Keyes


&&

.FIRE WEATHER...
High pressure will peak today with the ridge beginning to break 
down tomorrow. Very dry air will remain in place even with this 
initial breakdown of the ridge, including some very low overnight 
humidity recovery across the highlands. Haines of 5 and 6 are 
forecast both days as well. The weakening low moving through the 
region tomorrow will kick up the wind a bit, and it's possible we 
could be really close across portions of the central mountains and
Arco Desert to Red Flag conditions. For now, we aren't going to 
issue any type of headline...but it's certainly something to keep 
an eye on. The ridge weakens more on Friday, but Haines of 5 and 6
remain over most of central and eastern Idaho. Humidity will be 
on the rise during the day, but still many places will be around 
10-20 percent. Rain and mountain snow will increase finally later 
Saturday into Sunday. Wetting rains are likely for our mountain 
fire zones, especially 411, 413, 422 and 475 where some areas 
could receive 0.50-1.00 inches of rainfall/melted snow in about 48
hours. Other mountainous areas will see wetting rains, but 
amounts will be much lower. Amounts across the Snake Plain and 
Magic Valley MIGHT push between 0.10-0.20 inches, depending on 
location. Snow may fall as low as 6000ft Sunday morning, but any 
appreciable snow accumulations will likely be at/above 7000ft. We 
do expect these amounts to fluctuate until we get a lot closer to 
things kicking off, so definitely pay close attention over the 
next few days. It will be quite breezy over the weekend, but with 
much higher humidity...we won't be dealing with Red Flag 
conditions. High pressure tries to rebound early next week, but we
may still be dealing with occasional showers across the mountains
for the most part. Temperatures slowly warm up, but humidities 
will remain rather high despite any drying trend taking shape. 
Keyes

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$