046 
FXUS65 KPIH 210418
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
918 PM MST Thu Feb 20 2020

.UPDATE...

Think the high clouds drifting through the region will keep temps
a few degrees warmer than past couple of nights. With that said,
cold is cold. Only a couple adjustments to min temps based on
evening observations, mainly around Driggs and Island Park.

Valle

&&

.PREV DISCUSSION... /issued 149 PM MST Thu Feb 20 2020/ 

SHORT TERM...Tonight through Saturday night. High pressure
remains in control over East Idaho through tonight. Generally dry
conditions in the lower levels is expected to preclude development
of stratus/fog overnight, much like last night/this morning.
Expect a continuation of the cold temperatures, though higher
clouds streaming across the region tonight through Friday may
limit temps from bottoming out, but not much more than a degree or
two. Weak shortwave drives across the region on Friday, pushing
ridge axis east and allowing for deep closed low pushing into the
central and southern California coast. As this feature shifts
east into the four corners region through Saturday, next stronger
feature begins to push into the PacNW coastal states. This should
be the beginning of a brief warming trend ahead of the arrival of
the next system Sunday. DMH

LONG TERM...Sun through next Thu night. Approaching trough for Sun 
night starts clouding up the skies during the day Sun. A light to 
moderate snow event is expected from this storm. Its path is on the 
northwesterly flow track, and so, once again like so many storms 
this winter, will track with heavier snow over locations from Idaho 
Falls northward for the Snake River plain, and then moderate snows 
into the Caribou highland zones down to Bear Lake. After this storm, 
there is quite a difference in how the pattern evolves. The amount 
of dry northerly flow is in question, with the GFS fairly dry and 
colder, while the ECMWF brings another impulse through. Even by Tue 
there is a 12 degree difference in the forecast highs for the Snake 
River plain, which continues on Wed. Overnight lows also have a 
great disparity. Am tending towards the drier GFS scenario with 
colder lows and highs. The storm also comes with windy to possibly 
very windy conditions for Mon/Mon night, so blowing snow will likely 
be a factor, although a good crust on the top of the existing 
snowpack will lower the threat from blowing snow. Messick

AVIATION...Upper level ridging continues through Fri afternoon at 
least. The only place that has a fog threat is the north end of the 
valley, so have put some VCFG in the KIDA TAF, as there are patches 
of high humidity in the boundary layer expected late tonight. Wind 
remains light with some moderate valley wind during the mid to late 
afternoon. A few cirrus expected during the overnight hours, 
lingering into the daytime Fri, but no CIGs expected. Messick

&&

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

$$