Weather Service Report

FXUS65 KPIH 191942

Area Forecast Discussion
National Weather Service Pocatello ID
142 PM MDT Mon Mar 19 2018

.SHORT TERM...Tonight through Wednesday. Although weak high
pressure builds over the state, look for a couple of weakening
storms to keep clouds and light showers going through Tuesday
evening. Most of the showers will be in the highlands. A few are
possible over the Snake Plain, especially today based on the
latest radar loop. We are expecting any significant rain or snow,
or impacts. That said, if you do get a decent shower on top of might be enough for snow or graupel to cover the ground.
Although it's definitely NOT a slam dunk, we did see a bit of
stratus or fog where it cleared up a bit last night. That is
certainly possible again in the morning. We didn't include fog at
the moment based on the notion it will be quite sparse in
coverage. On Wednesday, the flow turns southwest ahead of the next
storm set to arrive for the end of the week. There will be a small
increase in moisture, enough that when the next "wave" comes
in...there is a better chance of rain and snow. It's still not
significant, but it's there. Snow levels will quickly rise through
the period and be at 6500-7500ft feet Wednesday afternoon. Of
course, this means warmer temperatures headed our way. By
Wednesday afternoon (which will likely be our warmest day), highs
will push 60 in some places across the Plain and into the southern
highland valleys. Elsewhere, look for a warm day in the mountains
where places like Stanley and Island Park will be well into the
40s.  Keyes

.LONG TERM...Wednesday night through next Monday. Concerns are 
growing over the moisture currently pooled off the California coast 
associated with a cutoff low. GFS and ECMWF are merging that low 
with another that will develop in the Gulf of Alaska Wednesday 
night. The end result will be a warm and moist southwesterly flow 
over Idaho that could potentially heavy rainfall to the valleys. 
Snow levels rise to around 7000 to 8000 ft by Thursday night while 
24-hour QPF in the valleys will be nearly 0.5 inches, and the 
mountains getting nearly twice that amount. Snow levels will work 
their way to the valley floors on Friday as a cold front pushes 
through the area. There is an outside chance of thunder on Thursday 
and Friday afternoon, where models produce some negative LIs along 
our southern border. Weather will remain unsettled through the 
weekend as we continue to see disturbances coming out of the deep 
upper trough off the coast. The trough should de-amplify somewhat 
while it pushes inland Friday night with the troughing pushing 
through completely by Sunday night. Thus have kept some PoPs in the 
forecast through the weekend with generally drying conditions 
beginning early next week. Hinsberger


.AVIATION...Sites should remain VFR except for DIJ, which continues 
to see lingering snowshowers. An upper low circulating off the 
Oregon coast is helping to provide some moisture for the showers 
today, which are being enhanced by terrain. No notable changes are 
expected for the next 24 hours, though the upper low is expected to 
begin to fill and move eastward through tomorrow afternoon, which 
may impact KSUN late in their forecast period. Hinsberger


.HYDROLOGY...Warm temperatures and potentially heavy rainfall are in 
store fore much of the area in the latter half of the week. 
Atmospheric river conditions will develop as a deep upper trough 
develops offshore. This moisture should arrive in the Central 
Mountains Thursday morning with snow levels rising above 7000 ft. 
This will likely accelerate snowmelt runoff as the warm and wet 
weather advances across the rest of Idaho. Snow levels should come 
back down on Friday, but there will be plenty of runoff making its 
way into the river basins. Flooding is a concern, but it's too soon 
to name specific locations. Hinsberger




Return to Home page

Western Regional Climate Center,