Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 250925

Area Forecast Discussion
National Weather Service Pocatello ID
325 AM MDT Tue Jul 25 2017

.DISCUSSION...Early morning radar imagery showing isolated rain
showers across the Central Mountains and south of I-86. Our
forecast thinking has not changed much regarding rainfall
potentials today and Wednesday, which keeps expected overall
totals below significant flooding concerns. We are still wary and
will monitor thunderstorm progressions closely as they are capable
of producing flash flooding in any one area, particularly over
burn scared areas. High precipitable water values over 1 inch
across much of our area today are noted, with these values
dropping over the Central Mountains tomorrow. For today, areas
favored for thunderstorms are south of I-86, in particular the
Bear Lake and Caribou Highland region. Thunderstorms are also
expected in portions of the Central Mountains. Cooler temperatures
remain on tap today and tomorrow with highs in the mid 80s across
the Snake Plain. Tomorrows activity looks to be much more
scattered in nature with no real indication of what area will be
favored at this time.

One notable change to this forecast is the increase in
precipitation potentials on Thursday. Forecast models are in now
in agreement that an additional shortwave trough will pass through
the region on this day, allowing for additional rain and
thunderstorms. Areas most targeted for this activity will be the
Snake Plain, the Upper Snake Highlands and Eastern Idaho. Speaking
of which, one area of concern of particular concern for
rainfall/flooding potentials over this now 3-day period is the
Island Park/Targhee National Forest and possibly into the Teton
Valley. Some ensembles are indicting upwards of 2 inches of
rainfall by Thursday, which we are not forecasting at this time,
but it is important to know this is possible. Average values are
closer to 3/4 inch with 1/4 inch today, and another 1/2 inch
tomorrow through Thursday. NP/Hedges


.AVIATION...Monsoon moisture streaming into ID today will lead to
scattered tstms over the mtns and isold to widely sctd tstms over
the Snake River Plain thru this eve. VFR conditions are expected to
prevail...altho gusty winds are possible near tstms. Hedges


.FIRE WEATHER...Monsoon moisture continues to stream into Idaho
today due to southwest flow aloft on the back side of the upper
ridge. Thunderstorms are expected to be fairly widespread today...
especially over the mountains. Deeper moisture today will result in
better chances for wetting rain...but also a reduced risk of dry
outflow winds. Lightning will still be an issue...but the greater
rainfall and higher humidity should temper the fire risk somewhat. Red Flag Warnings planned at this time. Denser cloud cover
will also cut a few degrees off the max temperatures. The pattern
looks similar for Wednesday...but on Thursday the upper flow becomes
more westerly. This will begin to cut off the monsoon moisture...
with thunderstorms decreasing in coverage into the weekend.
Temperatures warm back up over the weekend...along with a decrease
in humidity. Hedges



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