708
FXUS65 KPSR 271143
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
443 AM MST Mon May 27 2024

.UPDATE...Updated 12z Aviation Discussion.

&&

.SYNOPSIS...
Hotter temperatures are expected across the lower deserts today with
highs peaking in the high 90s to lower 100s, or around 5 degrees
above average. Hot and dry conditions will persist through the rest
of this week with very little day-to-day variability in temperatures.
Skies will remain mostly clear and winds should remain light overall
with the exception of typical afternoon breezes.

&&

.DISCUSSION...
Latest IR WV imagery reveals a low amplitude ridge centered over
the western CONUS. This ridging pattern will continue to build
today with 500 mb hghts rising to around 583-585 dam over
southeast CA and southcentral AZ. In response, warmer temperatures
are anticipated with highs reaching the upper 90s to around 103
degrees across the lower deserts. We will also begin to see
isolated pockets of moderate HeatRisk develop in southeast CA this
afternoon. Make sure to stay hydrated and take frequent breaks in
the shade if you have any outdoor plans for Memorial Day. Another
tranquil night is anticipated across the area with lows settling
into the mid 60s to lower 70s. On Tuesday, the aforementioned
ridge over the western U.S. will become more amplified as a
shortwave trough moves into the Pac NW. Hght anomalies over the
forecast area will increase further with highs solidly into the
triple digits and possibly the first 105 degree day for the
Phoenix Metro. Chances of 105+ degrees remain around 30-70% across
the lower deserts on Tuesday afternoon. Moderate HeatRisk will
also expand in coverage (20-40% in southcentral AZ and 50% in
southeast CA).

Ensemble members are still in good agreement that a shortwave trough
will pass through the Intermountain West on Wednesday. However, the
positioning of this trough looks to be too far north to provide any
noticeable cooling across the Desert Southwest. In fact, hght
anomalies will still remain above average heading through mid-
week which will keep temperatures mainly in the triple digits
across the lower deserts from Wednesday onwards. There could be a
slight uptick in breeziness each afternoon, but overall wind gusts
are expected to remain below 25 mph with the exception of western
Imperial County where gusts could reach as high as 35 mph
Wednesday and Thursday afternoons.

Heading into this weekend, 500 mb cluster analysis is indicating
positive hght anomalies building back over the region as ridging
aloft strengthens over N Mexico. This increase in mid-lvl
hghts/thickness suggest that temperatures will continue to remain
above average. Both Saturday and Sunday look to be hot with highs
mainly in the 100-105 degree range across the lower deserts. There
are indications in some of the global models that ridging will
become even more enhanced by the beginning of next week which could
result in even hotter temperatures. Latest NBM 75th percentile highs
in Phoenix are 107F Tuesday and 111F Wednesday next week. This
will certainly be something to keep an eye on in the coming days.

&&

.AVIATION...Updated at 1142Z.

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

No aviation weather concerns are anticipated through the TAF
period under mostly clear skies, aside from FEW passing high
clouds. Winds directions will follow their typical diurnal
tendencies, with speeds mostly aob 8 kt sustained and periods of
very light speeds and variability preceding direction switches.
Westerly gusts into the mid teens during the afternoon and early
evening cannot be ruled out. Confidence in reduced visibility (as
low as ~5SM) from dispersed wildfire smoke/haze this morning is
very low, though Hi-Res model guidance still suggests the
potential, and one or two sites have sporadically reported
visibilities below 10SM so far this morning.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns will exist through the next 24 hours
under FEW passing high clouds this morning. Winds will exhibit
extended periods of variability at both terminals this morning
before favoring SE at KIPL by 14-16Z at KIPL and S at KBLH around
17-19Z. Wind speeds will remain light (aob 8 kt sustained) until
late this afternoon/early this evening. Winds will establish out
of the W at KIPL early this evening and could develop gusts
between 15-20 kt, whereas directions will gain a more westerly
component at KBLH and pick up to around 10 kt late this afternoon.


&&

.FIRE WEATHER...
Hot and dry conditions will persist through this week with
temperatures topping out around 5 degrees above average. Daily highs
will reach the century mark in most lower desert locations beginning
today with widespread readings between 100-105 persisting through
the remainder of the week. MinRH values will be 10% or less across
the central and western deserts each afternoon and overnight
recoveries will continue to range from poor to fair at around 25-
40%. Winds are expected to generally remain below 15 mph, but a bump
in breeziness could result in pockets of elevated fire weather
concerns by the middle of this week (peaking on Wednesday).

&&

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

$$

DISCUSSION...Salerno
AVIATION...Whittock
FIRE WEATHER...Young/Salerno