Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 242004

Area Forecast Discussion
National Weather Service Pocatello ID
204 PM MDT SUN JUL 24 2016

.DISCUSSION...Dry northwest flow transitions again to southwest
flow overnight tonight into Monday. Weak shortwave pushes through
panhandle during the day Monday but moisture remains limited and
convection expected to remain north of SE Idaho. Similar feature
slides through region on Tuesday. NAM indicating better moisture
present south of Divide thus increased precip chances Central Mtns
and regions along Divide. GFS remains stingy on moisture and thus
dry. Do not expect much if any precip with any convection that
develops Tuesday afternoon/evening. Upper high reasserting itself
across Great Basin remainder of the week with temperatures
returning to above-normal levels. Models vary on placement of
center of the low, with long term indications for moisture surging
north around the high by the weekend. Both GFS and EC bring upper
low into BC Canada with trough axis reaching coast by Saturday,
and thus some hint of convection possible by Saturday afternoon.
Have kept precip chances well below climo at this point, but do
expect to lean into chances if trend continues. DMH


.AVIATION...Dry westerly flow will remain in place across the
region through the period, allowing mainly clear skies. The lack of
a strong pressure gradient will mean surface winds will be driven by
local terrain influences, and will be mainly under 12kts through the
period. AD/DMH


.FIRE WEATHER...Dry westerly flow will dominate the upper-air flow
through Monday across the region. Winds will be dominated by local
terrain influences, and will be strongest across the Arco Desert
through Monday, with gusty NW winds overnight where Central Mountain
Valleys drain into the desert. Gusty SW afternoon winds are expected
across the region as well due to up-valley flow. Despite the
gustiness winds are forecast to remain below red flag criteria
Monday. A disturbance will track eastward across the region on
Tuesday. A handful of computer models develop isolated thunderstorms
across the Lemhi region during the afternoon and early evening hours
Tuesday, impacting zones 475 and 476. The above-mentioned computer
models have demonstrated skill in placement and timing of convection
of late, so confidence is increasing in thunderstorm potential for
these areas on Tue, along with subsequent potential Red Flag
conditions. Would like to see another model or two jump on board
thunderstorm potential before going all-in on Red Flag, but this may
certainly be warranted if these upward convective trends continue.
Above-mentioned disturbance will also bring an increase in winds
Tuesday, with gusts across the Central Mountains approaching 25 mph
during the afternoon, and diminishing little above thermal belts
overnight. Winds are expected to be slightly weaker Wednesday, but
will still be approaching Red Flag. Similar conditions are expected
on Thursday. Models continue to indicate the potential for isolated,
dry thunderstorms on Saturday and Sunday as subtropical moisture
works into the region. Coupled with an approaching trough across the
PacNW, expect an increase in winds both weekend days as well,
perhaps exceeding Red Flag criteria for many areas. The combination
of low relative humidity values, gusty winds and isolated dry
thunderstorms could make for potentially volatile fire conditions
over the weekend, and this will need to be closely monitored through
the week. Otherwise, temperatures remain 5 to 10 degrees above
climatological averages through the week, with minimum relative
humidity values remaining quite dry. AD/DMH


.PIH Watches/Warnings/Advisories...

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