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000
FXUS65 KPSR 180518
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1018 PM MST Wed Apr 17 2024

.UPDATE...Updated 06z Aviation Discussion...

&&

.SYNOPSIS...
Dry conditions and above normal temperatures are expected through
early next week. High temperatures will run about 10 to 15 degrees
above normal across the lower deserts, with the potential for some
locations to reach 100 degrees, particularly on Sunday and Monday. A
weak disturbance will pass over the Desert Southwest late this week,
bringing widespread breezy conditions on Friday.

&&

.DISCUSSION...
Mid-level water vapor imagery shows a broad, flat ridge pushing into
the Desert Southwest, with the weak shortwave trough that was
positioned over our area for the last 24 hours moving off to the
east. Positive 500 mb height anomalies will persist through early
next week, leading to well above normal temperatures across the
lower deserts. Highs in the low-to-mid 90s will be common for many
lower desert locations through at least Tuesday, with Sunday and
Monday shaping up to be the warmest days. In the short term, we can
expect some upper level moisture to move overhead tonight into
tomorrow ahead of another weak shortwave trough that will begin to
traverse the region by late Friday. Mid- and high-level cloud cover
will act to slightly suppress the highs tomorrow (when the
greatest mean 500 mb heights, upwards of 582 dm, are forecast in
ensemble guidance), though temperatures are still anticipated to
reach the mid 90s.

The aforementioned shortwave trough that will begin to push overhead
late this week will bring widespread breezy conditions on Friday.
Afternoon gusts are expected to peak between 20-25 mph. A few
stronger gusts in excess of 30 mph will be possible out across
Imperial County going into Friday evening. Despite the dropping
heights with the trough passing through the region, temperatures
will see minimal change for the end of the week. The passage of the
weak trough will be replaced once again with ridging and
temperatures rising into the mid-to-upper 90s and potentially near
the century mark in a few warmer lower desert locales Sunday and
Monday. NBM probabilities for reaching or exceeding 100 degrees rise
to around 20-40% Sunday and Monday for some of these warmer areas
across south-central Arizona and southeast California.

Next week, an approaching trough off the West Coast will begin to
influence our area, though considerable uncertainty exists in the
timing of this trough moving onshore and its overall evolution. GEFS
and ECMWF members show pressure gradients along the southeast
periphery of the trough tightening overhead on Tuesday, which
would bring widespread daytime breeziness during the middle of
next week. Heights aloft would also begin to fall with the
approach of this system, leading to a gradual cooling trend into
the latter half of next week. At present, NBM inner quartile
ranges for high temperatures are greater than 5 degrees on Tuesday
and beyond, but the cooling trend is apparent.

&&

.AVIATION...Updated at 0505Z.

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

No major aviation weather concerns are expected through the TAF
period. Winds will continue to follow the typical diurnal
tendencies with speeds generally aob 8 kts. However, a period of
light southerly crosswinds is likely late Thursday morning and
early afternoon during the diurnal transition. High clouds will
increase over the area through tonight and persist through most
of Thursday with SCT-BKN coverage.

Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation weather concerns are expected through the TAF
period. Winds will be following diurnal tendencies with speeds
generally aob 12 kts. There will also likely be extended periods
of light and variable winds during the morning hours before speeds
pick up by the afternoon hours. High clouds will increase over
the area through tonight and persist through most of Thursday with
SCT-BKN coverage.

&&

.FIRE WEATHER...
Dry weather conditions will persist through the next week.
Increasing high pressure over the region will yield above normal
temperatures through the next week. Daily highs will rise into
the low to mid 90s each day across the lower deserts starting
today and continuing through the remainder of this week. Min RHs
each day will be in the 5-15% range, while overnight Max RHs will
be in the 20-40% range for most areas. Light, diurnal winds will
be favored with afternoon breezes gusting upwards of 20-30 mph on
Friday.

&&

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

$$

DISCUSSION...Whittock
AVIATION...Lojero
FIRE WEATHER...Smith