Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 260911

Area Forecast Discussion
National Weather Service Pocatello ID
311 AM MDT Wed Jul 26 2017

.DISCUSSION...Area of low pressure is currently located over
northern California. SE Idaho is situated in moist (precipitable
water values hover around 200 percent of normal) SW flow in
advance of this feature. Expanding area of upward motion combined
with ample moisture will create an environment favorable for the
continued development of precipitation. The question is...where
and when will precipitation be heaviest? Confidence is low in this
as forecast guidance is all over the map. However, higher terrain
areas should be favored as terrain is a source of lift so have
focused higher precipitation chances over these areas. One
limiting factor for convective development today will be cloud
cover, and clouds should be fairly extensive across the area this
morning. Dry slot noted over northern NV should spread across
southern portions of the forecast area today, allowing for some
afternoon sunshine and destabilization of the atmosphere. Little
wind noted all the way up to 15,000 feet elevation today, thus
showers and storms will not have much forward speed. Combined with
ample available moisture, showers and isolated storms will have
the potential to produce locally heavy rainfall. On Thursday, the
upper low currently over CA gradually weakens and evolves into
more of an open wave while passing over Central Idaho. This wave
will move across our region during peak heating. Thus, shower and
thunderstorm activity should be more organized and the Snake Plain
will see a greater chance at seeing measurable precipitation.
Some storms may be strong, capable of producing gusty winds. Storm
motion will be faster, however still plenty of moisture around
for brief, heavy downpours.

Ridge of high pressure is then expected to become re-established
across the Great Basin through early next week. As a result,
temperatures will be back on the rebound by late this week through
the weekend and into early next week. Isolated showers and
thunderstorms remain possible each day, with best chances
coincident with peak daytime heating -- or in the late afternoon
through early evening hours and focused over higher terrain areas.


.AVIATION...Monsoon moisture flow will result in continued shower
and tstm activity thru tonight. VFR conditions are expected to
prevail...but gusty winds are possible near tstms. Hedges


.FIRE WEATHER...Monsoon moisture continues to stream into Idaho
again today due to southerly flow aloft ahead of an upper low over
northern California. Scattered showers and occasional thunderstorms
will be the rule today and tonight. Heavy cloud cover is keeping
temperatures down...which limits the thunderstorm activity somewhat.
The deep moisture also leads to increased rainfall amounts and
higher humidity. Although lightning and gusty outflow winds will be
an issue...the overall fire weather threat should be reduced enough
to not require a Red Flag Warning. The upper low dissipates
tonight...curtailing the monsoon flow. Residual moisture will still
allow for scattered showers and thunderstorms on Thursday...but
activity will be significantly less Friday through the weekend.



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