Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pocatello Idaho
230 am MDT Wednesday Sep 2 2015
Discussion...a deep upper low over the central British Columbia coast this morning
is expected to drop south to the Washington/or coast by Friday morning. Upper
level flow will become more southwesterly and increase today
resulting in windy conditions this afternoon...especially at the higher
elevations in the central mountains the SW flow may drag some
subtropical moisture out of the Great Basin into southeast Idaho this evening...
setting off isolated thunderstorms in the eastern Highlands. The rest of the
forecast area will remain dry through tonight. As the upper low moves
south...showers/tstms will creep into the central mountains on Thursday...
spreading to the upper snake Highlands by Friday. Still may see isolated
activity in the southeast corner as subtrop moisture continues to get
pulled in by the SW flow.
The picture changes by Saturday...as the upper low moves into the
Great Basin. Showers/isolated thunderstorms will become more widespread...and
temperatures much cooler. The upper low moves into Idaho Sat night. Models
showing a dry slot moving into southern Idaho...pushing most of the
precipitation into the northern parts of the forecast area. The upper low
fills and mover NE out of the area late Sunday...with all areas
drying out Sun night.
Both GFS and European model (ecmwf) bring an upper trough through Idaho on Monday...but with
differing configurations. Both models agree that this system will
be dry. Temperatures climb back to more seasonal readings Tuesday and Wednesday.
Aviation...expect winds to increase this afternoon at Ida and pih
to sustained 15 to 25 knots and gusts 25 to 35 knots after 18 to
20z. Expect lighter winds at byi in the 10 to 15 knot range
sustained wtih 10 to 15 also at sun with gusts around 20 knots.
Will be VFR across the board with some moisture pushing into
southeast corner tonight with some vcsh at pih and Ida.
Fire weather...very dry and mild conditions continue over eastern
Idaho today. Strong winds aloft will mix down mainly in the
northern and eastern parts of the district and a red flag warning
remains in effect for zones 475...476 and 410 beginning at noon and
continuing through 9 PM. Gusts of 25 to 35 miles per hour are possible this
afternoon. Humidity will bottom out in the 15 percent range across
those zones as well. Winds not expected to be quite as strong
further south and west so the warning limited to those three zones.
Upper level system continues to push east Thursday with isolated
thunderstorms possible. Showers and much colder temperatures are
likely Friday through Sunday with wetting rains likely in zones 475
red flag warning from noon today to 9 PM MDT this evening for