Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 241538
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
938 AM MDT Mon Jul 24 2017

.UPDATE...First round of moisture from low off the northern
California coast is spreading showers into western Idaho this
morning with isolated lightning strikes. Reports from the west
side indicate showers ranging from 0.10 to 0.25 in rainfall as the
quickly passed by. The leading edge of the showers is nearing the
Garden Valley to Featherville line and should be moving into the
Custer and Blaine Counties sometime between 10am and noon.
Expecting additional development through the day as more moisture
combined with heating and instability to fire off isolated to
scattered showers and thunderstorms region-wide. Heavy rains are
possible with stronger storms so those near recent burn scars
should pay particular attention as storms pass. First look at
models continue the on again/off again nature of showers and
thunderstorms through Thursday. Updates to the forecast have
already been posted.  VP




&&

.PREV DISCUSSION... /issued 310 AM MDT Mon Jul 24 2017/

SHORT TERM...Today through Wednesday...Evidence that moisture has
begun to work its way into our area is noted on satellite imagery
in the form of scattered cloud cover over southern and western
Idaho. An area of low pressure is currently located near the
intersection of Nevada/Idaho/Oregon with some showers expected to
initiate as a result this morning across the Central Mountains and
throughout the Eastern Magic Valley. This activity is not expected
to be severe. Our focus then turns to an upper closed low, which
will remain situated over northern California and allow for
widespread moisture to be lifted northward across the region. No
forecast model is necessarily agreeing with each other at this
point, still. Expect a change in our weather pattern early this
week, with increased cloud cover and widespread chances for
showers and thunderstorms. For today, the concern is scattered
thunderstorms leading to a fire starts. Expect scattered
thunderstorms across the Central Mountains, Southern Highlands and
Upper Snake Highlands from this afternoon through early this
evening. It may be possible to get a thunderstorm in the Snake
Plain as well. These storms will be capable of gusty winds and
frequent lightning strikes. Activity will diminish overnight but
not dissipate altogether, therefore a chance for thunderstorms
continue tonight through tomorrow morning.

Smoke may be noted from the Martin Canyon and Hansel Wildfires
across the Arco Desert and Caribou Highlands, respectively.
Transport winds will generally be toward the east or east-
northeast from these fires. The forecast for Tuesday and Wednesday
is calling for widespread 1/2 inch or more rainfall totals for
all mountainous locations with approx 1/4 inch expected in the
Snake River Plain during this 48 hour period. Flooding is still a
concern for burn scar areas tomorrow and Wednesday and will be
monitored as there is potential for 1 inch rainfall (or more)
totals during these days. The confidence in the forecast for the
rainfall totals is still quite low. NP/Hedges

LONG TERM...Thursday through Monday...Forecast models are
deciding if there will be passing shortwave Thursday or not on
Thursday. If so, there will be continuing showers and
thunderstorms as predicted by the European solution. Fridays
forecast seems to generally be in agreement between each long term
solution, where high pressure builds back into our region and
precip generally clear our area. Warming temperatures back into
the 90s are expected. For the weekend, an isolated chance for
showers and thunderstorms are forecast in the Central Mountains
resulting from moisture wrapping around the high. NP/Hedges

AVIATION...Monsoon moisture flowing into ID today will result in
increased tstm threat this aftn/eve. Although VFR conditions are
expected to prevail...gusty outflow winds can be expected with
tstms. Hedges

FIRE WEATHER...Monsoon moisture is expected to flow into Idaho
today on southerly flow aloft. This will fuel thunderstorms this
afternoon and evening over much of the region...with the greatest
coverage in the central Idaho mountains...eastern Magic Valley...
south central highlands...and upper Snake Highlands. Thunderstorms
are expected to produce frequent lightning and erratic outflow
winds as high as 45 mph. Have added FWZ422 and 476 to the Red Flag
Warning due to LAL of 6 and critical fuel conditions. The rest of
the region should only see isolated to widely scattered
thunderstorms...but gusty outflow winds and lightning are still
concerns. In addition... afternoon humidity readings are expected
to fall to the lower teens in most areas. The monsoon moisture
flow continues into Wednesday... with thunderstorms becoming more
widespread. Red Flag Warnings may again be necessary on
Tuesday...although temperatures will be a little cooler and
humidity higher. Thunderstorm activity decreases Thursday through
the end of the week as more westerly flow pushes the monsoon
moisture out of the area. Hedges

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for IDZ422-425-427-
476.

&&

$$



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