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Area forecast discussion 
National Weather Service Pocatello Idaho
149 PM MDT Tuesday Jul 22 2014

Discussion...east Idaho remains under influence of southwest flow
today and tonight. Shortwave pushing northeast from California
working with deep low off British Columbia Canada coast to maintain moist flow
into western portions of state including central mountains.
Already seeing broad cumulus field across central mountains along
with cirrus shield extending southwest toward California feature.
Radar picking up weak returns over pahsimeroi and Lemhi regions
early this afternoon. NAM and GFS continue to produce scattered
convective development within this zone though recent hrrr runs
less favorable for convection across the region. Models maintain
relatively thin band of activity overnight just along western edge
of forecast area boundaries so will keep lower probability of precipitation through the
central mountains overnight and into Wednesday morning. Elsewhere much
drier flow in place with precipitable water values dropping significantly
overnight through the snake plain and southern/eastern Highlands.
Strengthening surface low ejects north into southern Idaho
overnight with good southerly flow across the region helping to
enhance drying. Flow turns southwest during the day Wednesday as
northern low center reaches pacnw coast and dry punch extends
across most of eastern Idaho. Have kept weak probability of precipitation across central
mountains but confidence is low for precipitation chances with dry
upstream flow on WV Sat imagery. Breezy conditions expected but
marginal at this time for even lake wind concerns. Upper low
ejects east along Canadian border through Thursday...pushing dry
cold front through the region early in the day. Cooler but windier
day on Thursday with some concerns for fire /see discussion
below/. Guidance showing wide spread in wind values so will leave
current grids just below advisory conditions at this time.

Friday through Sunday Ridge rebounds through the intermountain
west. Warmer temperatures and dry conditions will continue. Models still
hinting at some hint of a return to monsoonal type flow by Monday.
GFS and European model (ecmwf) differ slightly in amount of convection and spread
Monday into Tuesday. Believe isolated probability of precipitation over higher elevations
will suffice for now until clearer picture develops. Dmh


Aviation...VFR conditions expected through the period at all taf
sites. Thunderstorms are expected once again in the central
mountains but will likely be north of ksun so kept in a mention of
thunderstorms in the vicinity. Otherwise...windy conditions are expected to set up Wednesday
afternoon and especially Thursday afternoon.


Fire weather...lingering thunderstorms can be expected today in the
central mountains as an upper low begins to move inland in
Washington state. The rest of the area will be under drier air
moving in from the south. A drying trend is expected to begin for
the entire area Wednesday as that upper low moves along the Canadian
border...and last through at least Saturday. As the low moves past
the area...a dry cold front will pass through southeast Idaho late Wednesday
night into Thursday morning which will decrease relative humidity values and increase
winds significantly in the afternoon. Currently have a Fire Weather
Watch out for all critical zones for Thursday afternoon for the
potential of a red flag day occurring as a result of low relative humidity and high


Pih watches/warnings/advisories...
Fire Weather Watch from Thursday afternoon through Thursday
evening idz410-425.

Fire Weather Watch from Thursday afternoon through Thursday
evening idz422-427.



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