Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/01/23
Area Forecast Discussion
National Weather Service Pocatello ID
107 PM MDT Sat Sep 30 2023
.SHORT TERM...Tonight through Sunday Night.
A low pressure system centered over western Nevada will move to
northeastern Nevada tonight. An organized band of showers will
develop across Utah this evening and move north into our area late
this evening and overnight resulting in high chances for rain across
much of the area. On Sunday, the low will stay and weaken across
eastern Nevada. The band of widespread showers will move northward
during the morning with showers becoming scattered in coverage
during the afternoon. Best chances for showers through the day are
across the Magic Valley into the Central Mountains because of their
proximity to the low. Chance for showers will diminish greatly
Sunday Night as we lose instability from daytime heating. Most
likely rainfall amounts are around 0.25 inches with around 0.50
inches in the Central Mountains and Southern Highlands. Although
there is a 25% chance of 0.50 inches across the Snake Plain and
Magic Valley and 0.75 inches across the South Hills and Central
Mountains. The Upper Snake Highlands could miss out on the better
precipitation amounts because the band of widespread rain is
expected to remain mainly west of there. Still, the Upper Snake
Highlands will most likely around 0.10 inches. Snow levels are high,
generally around 9000 feet, but some snow could be found on Galena
Summit. Looks like we may be unstable enough Sunday afternoon for a
20 to 30 percent chance of thunderstorms. However, instability is
most likely not enough for anything too exciting in terms of hail or
outflow winds.
13
.LONG TERM...Monday through Next Saturday.
The center of the low will continue lifting to the northeast on
Monday and the trough will slowly shift eastward on Tuesday as high
pressure sets up along the west coast. During this timeframe
precipitation will become more heavily concentrated over the eastern
mountains, where around a quarter of an inch to half an inch of QPF
will accumulate over 48 hours. The National Blend 75th and 90th
Percentiles suggest the half inch to one inch range. Only a couple
extra inches of snow will accumulate on the highest peaks of the
central mountains during this time. High pressure will build in
behind this slow moving system, however models continue to show some
differences regarding the placement and strength of the ridge come
late week. Under northerly flow aloft, dry conditions are expected
Wednesday through the end of the extended period. Under high
pressure, daily highs will warm by several degrees each day and will
finally run within a few degrees of normal by next weekend. However,
overnight temperatures under clear skies will likely drop low enough
to support frost formation across the Snake Plain Wednesday and
Thursday mornings. Cropp
&&
.AVIATION...Breezy conditions at Snake Plain TAF locations with
gusts to 20 kts likely for the remainder of the afternoon. Upvalley
wind at SUN could prove troublesome for incoming aircraft until
around 03z. Scattered showers will develop this evening becoming
widespread from IDA westward overnight. Ceilings through 18z may
remain VFR at PIH and IDA but could go MVFR during the afternoon as
cooler air works in. Threat for lower ceilings exists at BYI and
most likely at SUN where a slight chance for IFR conditions exists
late tonight into Sunday as rain could persist there through much of
Sunday.
13
&&
.FIRE WEATHER...
The closed low will over California will shift into Nevada and then
lift northward into Idaho early tomorrow. Winds will be breezy
today, especially north and south of the Snake Plain along our
borders with Montana and Utah, with southerly sustained winds 20 to
30 mph and gusts 35 to 45 mph. While all Fire Weather Zones aside
from Zone 410 could experience rain showers today, the main push of
precipitation will arrive after midnight tonight and continue
through Sunday evening. During this 24-hour timeframe, half an inch
to one inch of QPF is expected across the southern highlands and
central mountains, with isolated areas receiving over an inch. Zones
410, 425, 411, and 413 will likely receive more on the order of a
half inch or less, with closer to three quarters across the highest
elevations of the eastern mountains. Snow levels will remain around
8,500 feet and higher, so the only snow expected is along the
highest peaks of the central mountains. Precipitation will taper off
late evening Sunday and become concentrated over north-central Idaho
and further east toward the Wyoming border on Monday and Tuesday as
the low slowly departs to the northeast. Behind this system, high
pressure will build over the west coast, resulting in predominately
dry conditions for the second half of next week as well as a gradual
warming trend. Temperatures will finally be within a few degrees of
climatological norms by next weekend. Cropp
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$