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251
FXUS65 KPSR 091010
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
310 AM MST Thu May 9 2024

.SYNOPSIS...
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Trending towards tranquil weather conditions is the overall
outlook for the Desert Southwest over the next several days.
Residual afternoon breeziness will linger into the weekend, ahead
of much calmer conditions heading into next week. Below normal
temperatures will trend warmer over the next few days, with
increasing chances for triple digit high temperatures across the
lower deserts heading into next week.
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&&

.DISCUSSION...
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Clear skies continue to persist, with upper level troughing
across western CONUS bringing more west to east flow across the
region early this morning. This longwave trough will continue to
linger across the region, but weaken over the next few days,
resulting in temperatures moderating going through the weekend. A
weak jet at the base of the trough will continue to result in
afternoon breeziness, especially across the higher terrain of
southcentral Arizona going through Saturday.

Strong ridging in the Pacific Northwest region will slowly bring
somewhat higher heights to the Desert Southwest through late
weekend, bringing a return of above normal temperatures into early
next week. The likelihood of the next 100 degree day will increase
with each day, with the first reasonable chance (50-70%) for 100
being out across the lower Colorado River Valley as early as
Sunday (also, would be Moderate HeatRisk conditions for this area).
Chances will continue to increase for the Phoenix area into early
next week, with a 30-50% chance of 100 degree highs as early as
Monday. The one caveat to keep an eye on, is ensemble guidance
continues to linger negative to neutral height anomalies across
the Desert Southwest through mid- week, so should the troughiness
end up being deeper than advertised, then triple digit high
potential may be delayed until late next week.

Speaking of the middle to later portions of next week, ensemble
clustering show considerable spread, as the evolution of the
aforementioned trough will determine the magnitude of the warming
trend during this period. However, there is a signal of more
robust ridging building across the region late week, so
temperatures topping the century mark would have a much higher
likelihood should that scenario come to fruition. For now, the NBM
deterministic forecast shows warming through Sunday, with highs
hovering right near 100 degrees for the lower deserts through the
early and middle portions of next week. Rain chances are
essentially zero through the forecast period, but an increase in
moisture starting Sunday and lingering into the middle of next
week are expected to result in increasing clouds in the higher
terrain during the daytime hours.
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&&

.AVIATION...Updated at 0535Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
West winds will subside over the next couple hours and shift east
by 10-11Z. Winds will remain light through the night, with the
exception of 10-12 kts at KIWA. Winds shift back west by 16-17Z
Thursday. Westerly winds Thursday will increase up to 10-15 kts,
with gusts up to 20-25 kts, in the afternoon. SKC will prevail.

Southeast California/Southwest Arizona including KIPL and KBLH:
Light W-NW winds at KBLH will prevail through tonight, while light
W winds at KIPL will eventually become variable early Thursday
morning. Northerly winds are expected at both terminals during the
day Thursday. Speeds will remain light at KIPL, while northerly
gusts at KBLH will reach up to around 20 kts Thursday. SKC will
prevail.

&&

.FIRE WEATHER...
Typical springtime breeziness with afternoon and early evening wind
gusts of 20-25 mph will persist through the weekend. These breezy
conditions combined with dry fine fuels, and low RHs will likely
create some elevated fire weather conditions. MinRHs will be in the
5-10% across the lower deserts and in the 10-15% range across the
higher terrain. Overnight recovery will be poor and in the 20-40%
range. Seasonal temperature continue through Friday before a gradual
warming trend sets in this weekend and continues into next week. Dry
conditions will also persist into next week.

&&

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

$$

DISCUSSION...Young
AVIATION...Benedict
FIRE WEATHER...Young/Berislavich