257
FXUS65 KPSR 081137
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
437 AM MST Wed May 8 2024

.UPDATE...Updated 12z Aviation Discussion.

&&

.SYNOPSIS...
The weather pattern will continue to support near normal
temperatures through Friday with daily breezy conditions. The
clear to mostly clear skies will persist into the weekend with a
warming trend pushing temperatures to above normal and highs
potentially topping out around 100 degrees as early as Sunday
across portions of the lower deserts.

&&

.DISCUSSION...
An expansive upper level trough will continue to impact the
majority of the Western U.S. over the next several days. A low
pressure center over the Northern Plains is now retrograding
westward into Montana, while a shortwave trough is also digging
southward across Utah. This shortwave will continue to weaken as
it tries to move into Arizona today, but it will at least
influence winds today while keeping temperatures near seasonal
normals. Northerly gusty winds of 25-35 mph are expected to affect
the Lower CO River Valley this morning with gusty winds of 20-25
mph expanding eastward across southern and central Arizona during
the afternoon hours.

The upper level trough will continue to influence the Desert
Southwest through at least Friday with forecast temperatures
hovering within the normal range today and Thursday. Starting
Friday, some weakening of the trough will allow for some rising
heights aloft and the beginning of a warming trend through the
weekend. By Saturday, NBM forecast highs show readings topping out
in the mid 90s over much of the lower deserts.

A Pacific ridge is then favored to move over much of the Western
States by Sunday, but ensemble guidance still shows lingering
influences of the trough over Arizona. The ridge should be enough
to boost lower desert temperatures across southeast CA on Sunday
up to around 100 degrees, while the Phoenix area stays in the mid
to upper 90s. There is also evidence of a slight moisture increase
Sunday into early next week across Arizona, but in reality any
low potential for shower/thunderstorm activity would only exist
across the Arizona high country. Guidance eventually shows the
ridge briefly taking over across all of the region early next
week, but it will be in a weakening phase as H5 heights are at
most 578dm. However, this may be enough for some of the south-
central Arizona deserts to see highs nearing 100 degrees. Beyond
early next week, model spread increases considerably with some
members showing a weak low center moving over or near the region,
while others show potential for a stronger ridge. Forecast
confidence in temperatures during the latter half of next week is
quite low due to these discrepancies, but seasonably dry
conditions are expected to continue.

&&

.AVIATION...Updated at 1140Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No significant weather issues will exist through Wednesday night
under clear skies. Typical diurnal wind tendencies will continue,
with easterly winds becoming westerly late this morning/early
afternoon. Gusty winds 20-25kt should affect terminals during
afternoon into the early evening before relaxing mid evening and
easterly winds developing once again during the overnight hours
tonight.

Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty winds associated with a frontal passage early this morning
will be the primary weather issue under clear skies. Wind
directions will favor W/SW ahead of the front, with northerly
winds quickly strengthening with the frontal passage. Gusts
30-35kt may sweep through KBLH around sunrise with a chance of at
least lofted dust immediately behind the front through mid/late
morning. There is around a 20% chance of surface visibilities
dropping into MVFR category with the strongest gusts though
confidence and potential duration is too low to include in this
TAF package. Gusts should be far more limited or absent at KIPL.
Wind speeds will generally weaken through the daylight hours with
a loss of gustiness by sunset.

&&

.FIRE WEATHER...
Breezy and continued dry conditions are expected over the next
couple of days with wind gusts around 20-25 mph for most locations
this afternoon and early evening and up to 20 mph on Thursday. The
combination of dry fine fuels, low RHs, and breezy conditions will
likely create elevated fire weather conditions during the
afternoon hours today. Stronger winds of 30-40 mph at times will
also be possible this morning across portions of southeast CA and
far western AZ. MinRHs will be in the 5-10% range across the lower
deserts to 10-15% across the higher terrain. Overnight recoveries
will be in the 20-40% range. Expect temperatures near seasonal
normals through Thursday before warming to above normal over the
weekend as seasonably dry conditions persist.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Kuhlman
AVIATION...Young/18
FIRE WEATHER...Kuhlman