Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 150900

Area Forecast Discussion
National Weather Service Pocatello ID
300 AM MDT Tue May 15 2018

.SHORT TERM...Tonight through Thursday night.

Our low pressure system that has been producing unsettled weather is
over northern Nevada this morning. The low will continue to weaken
and move northward to near the Oregon/Idaho border. We`ll see
another day of isolated to scattered afternoon thunderstorms. Best
threat for storms will be across the central Idaho mountains because
of the combination of terrain with proximity of the low pressure
center. By Wednesday, this low will have all but washed out and a
new low will be moving through central California. This new low will
arrive into Nevada by Thursday. The new low will bring with it a
renewed source of moisture which will enhance our chances for
showers and thunderstorms over the next few days. Best threat will
remain across the central Idaho with the mountainous terrain will
further add to the chances. Rainfall amounts will vary wildly. Areas
that see thunderstorm activity could easily see up to a quarter of
an inch of rain. Small hail and gusty winds will remain possible
with these storms as well.


.LONG TERM...Friday through next Monday.

Splitting of energy in the Eastern Pacific continues to be a bit of
a problem for the extended forecast. GFS is most consistent model
run to run, while the ECM is showing a bit of a diurnal variation
lately and this was no exception with the latest 00Z run. Much of
the difference appears to be in the southern track, for example the
previous model run tracked through east central Nevada Tuesday
morning and the latest run tracked the same feature south of Las
Vegas. Fore this forecast, used a good dose of persistence from the
previous forecast and the latest GFS. Model consistency of the low
pressure trough crossing Montana on Friday was pretty good, should
be an active day for showers and thunderstorms. Sunday appears to
have less forcing, but airmass is still moist and unstable in
generally southwesterly flow pattern. Sunday and Monday will likely
be unsettled as well with the next disturbance tracking across
southern California. Temperatures remain a little above normal
through the period. RS


.AVIATION...Low pressure disturbance over Nevada moves
northward to Idaho today, tracking towards the west side of the
state. Early afternoon convection favors Thunderstorms vicinity of
KSUN. Bit of a dry slot in the Snake Plain. Afternoon/evening
convection favors KBYI/KSUN and KDIJ. Southwesterly flow on Wednesday
should favor convection at all 4 TAF sites. RS



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