Wildfire in Idaho, July 19 to 30, 2019

Area Forecast Discussion
National Weather Service Pocatello ID
105 PM MDT Fri Jul 19 2019

.SHORT TERM...Tonight through Sunday
Relatively quiet weather will dominate the weekend as dry
conditions hold across the region. With dry and windy conditions
this evening, the biggest concern will remain Fire Weather. Will
continue to carry the Red Flag Warning through late evening. More
information available below in the Fire Weather section.

The pressure gradient will loosen Saturday and Sunday afternoon as a
broad ridge of high pressure builds in from the south. This will
bring about lighter winds than previous days. While winds will
slacken, the strengthening ridge will bolster surface temperatures
from mid 80s on Saturday into the mid 90s on Sunday. These warm
daytime temperatures will be further enhanced by sunny sky
conditions.
TAX

.LONG TERM...Sunday night through next Friday
Hot and dry conditions carry into next week as the high pressure
center slowly churns through the Great Basin. The anti-cyclonic flow
will begin to spread modest monsoonal moisture back into the area
Monday afternoon through at least mid-week. This moisture return
will fuel isolated shower and thunderstorm chances Monday, Tuesday
and Wednesday, but will also increase the overall humidity in the
area. As temperatures top out well-above average Monday and Tuesday,
the increased humidity will cause some uncomfortable to almost
dangerously hot conditions. While not certain, potential for heat-
related advisories exists early in the week.

Model solutions begin to diverge a bit towards the second half of
next week as a trough tries top the stout western ridge. Currently
don't see any reason to believe that the ridge will break down or
shift far enough south to lead to a major cool down, so slightly
above-average temperatures should hold through at least the end of
next week.
TAX

&&

.AVIATION...VFR conditions will hold through the duration of the TAF
period for all area terminals. Strong, gusty winds will give way to
calming with terrain-induced flow overnight tonight. Winds will
again increase Saturday but in general they will be lighter than the
last few days.
TAX

&&

.FIRE WEATHER...Breezy conditions are ongoing this afternoon across
central and eastern Idaho, especially across the Snake Plain. The
RED FLAG WARNING for zones 410 and 425 will remain in place for the
rest of the afternoon and evening. We may actually see our lowest
humidity values arriving a couple of hours later, but we are still
expecting critical conditions to be reached with the warning area.
The weekend will remain dry and warmer. Humidity values will
continue to be dropping overall, including poor humidity recovery at
mid/upper slopes and even across portions of the Arco Desert through
Monday. We are still expecting valley temperatures Monday in the 90s
and even low 100s in a few places. This is where the forecast gets a
bit tricky. There seems to be some disagreement on when we see the
initial surge and the best day for thunderstorms early next week. It
still looks like that Monday will be when we see enough moisture,
when combined with very warm temperatures, for isolated dry storms
across the central mountains. After that, it seems that 1) this
round of monsoon moisture may not be as strong as previously
forecast), and 2) it may not be around for long. The latest
forecasts try to thin out moisture on Tuesday, and actually allowing
for temperatures similar to Monday. They also bring a front through
on Wednesday now and completely dry us out. We went with the idea of
isolated dry storms on Tuesday across the central mountains, but
nothing elsewhere. Then on Wednesday, we went with isolated storms
across the mountains and potential scattered across the central
mountains. In reality, we expect to see some changing forecast
through the weekend and even on Monday...until we get a better idea
of what we might be facing. The main theme should be that we may see
potential lightning issues following a stretch of really warm and
dry conditions. Keyes

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for IDZ410-425.

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