Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/14/21

Area Forecast Discussion

National Weather Service Phoenix AZ

 428 PM MST Tue Apr 13 2021

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Dry conditions will remain across the region this week, but the
influence of a weather disturbance north of the area will result in
a slow decline in temperatures through Thursday. Breezy to locally
windy conditions are forecast for today through Thursday with
locally daytime breezy conditions through the rest of the week.
Increasing high pressure should then turn temperatures gradually
warmer heading into the weekend, potentially topping 90 degrees
again as early as Saturday.

&&

.DISCUSSION...
A closed upper level low is currently spinning near NW Nevada
this afternoon. Heights have begun to gradually fall across the
Desert Southwest and ACARS aircraft soundings have shown a slight
atmospheric cooling from 24 hours ago. As of 2 PM MST this
afternoon, Sky Harbor has only been up to 89F. If this were to
hold it would be the first time this month with a high less than
90F in Phoenix, ending the 12 day streak. Gradual cooling is
expected to continue over the next few days as the closed low
slowly meanders through the Great Basin, remaining just north of
the region. The coolest day of the week is still expected on
Thursday, with forecast lower desert highs in the low 80s, which
will be below normal readings for the first time in over half a
month if observed.

The main forecast concern over the next couple days will be an
increase in winds leading to heightened fire weather danger. Dry
conditions will remain entrenched across the Desert Southwest as
the low slides by, but a tightening gradient will lead to
increased west southwesterly winds by this evening. Wind gusts of
20-30 mph are likely areawide with gusts to 35 mph more likely
across southeast California. The stronger winds across Imperial
County may also lead to some modest patchy blowing dust, but dense
blowing dust does not look probable. A wind advisory will take
effect at 3 PM PDT this afternoon for far southwest Imperial
county, where wind gusts may approach 55 mph this evening and
overnight. The gradient is likely to remain nearly as strong into
Wednesday, so winds Wednesday may end up being a repeat of
today`s. Continued breezy conditions are likely on Thursday, but
more focused over the eastern CWA. Periods of high clouds are
also expected through the end of the week with Thursday likely
seeing the greatest sky coverage and perhaps some virga.

An omega blocking pattern later this week should allow the then
weakening low to the north to linger through much of the coming
weekend. However, with the low weakening substantially, the air
mass over the region will slowly warm starting Friday leading to
high temperatures near 90 degrees this weekend. Early next week
still shows high model spread with around 2/3rds of the ensemble
members showing a modest ridge building across the Western U.S.,
while the rest show a potential trough digging through the Western
U.S. No matter how it plays out, above normal temperatures look
nearly certain for early next week as ridging is expected to be in
place over the Desert Southwest. Thereafter however is much less
clear as another cool down could be in store if the potential trough
ends up meandering into the region at some point during the
latter half of next week.

&&

.AVIATION...Updated at 2325Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Westerly winds will predominate through this evening with speeds
frequently reaching 10-15 kts and gusts of 20-25 kts. Speeds/gusts
will subside after sunset. A late easterly switch is anticipated
to occur around 10Z at speeds below 7 kts. For Wednesday, another
extended period of southerly crosswinds are possible between
16-20Z before westerly afternoon winds resume. The afternoon
westerlies will again have elevated speeds around 10-12 kts and
gusts potentially reaching 20 kts.

Southeast California/Southwest Arizona including KIPL and KBLH:

Strong westerly/southwesterly winds will prevail at both TAF sites
at speeds of 15-20 kts and gusts nearing 30 kts. Speeds will
slowly subside after sunset and through the overnight hours down to
8-12 kts. At KBLH, a more discernible drop in the overnight wind
speeds is likely, at which point, southerly headings will prevail.
However, another round of strong southwesterly winds are anticipated
by tomorrow afternoon with speeds approaching 20 kts and gusts
nearing 30 kts. Localized areas of blowing dust and/or slant range
visibility issues from lofted dust cannot be ruled out this
evening or tomorrow afternoon.

&&

.FIRE WEATHER...
Friday through Tuesday:
Near normal temperatures are expected Friday, but temperatures
will gradually warm back up to the low 90s area wide by Sunday or
Monday. Afternoon breeziness will be common with the typical
upslope favored areas experiencing the strongest gusts. Stronger
winds will be likely Saturday and Sunday yielding a period of
elevated fire danger. Dry conditions will prevail through the
period with afternoon minimum humidity values falling to 6-10%
while overnight recovery will be poor only bouncing back to a
20-30% range.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 5 AM PDT Wednesday for CAZ562.

&&

$$

DISCUSSION...Benedict/Kuhlman
AVIATION...AD/Hirsch
FIRE WEATHER...Benedict/Kuhlman