547
FXUS65 KPSR 272039
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
139 PM MST Mon May 27 2024

.SYNOPSIS...
Quiet conditions are in store as high pressure encompasses much of
the western United States during the majority of the next seven
days. A weak trough will begin to traverse the region Wednesday
but will result in almost no noticeable changes in conditions
outside of perhaps a minimal increase winds. Widespread triple-
digit heat is expected across the Desert Southwest, with very
little change in day-to-day temperatures through at least the
upcoming weekend.


&&

.DISCUSSION...
Current analysis reveals high-pressure building over the Desert
Southwest and much of the western CONUS to start the week. This
ridging pattern is projected to build further over the next few
days, with heights aloft rising to 583-585 dam over our forecast
area. This amplification will result in a continued warming trend as
temperatures for today are forecasted to be a few degrees higher
compared to what was observed yesterday, with afternoon highs
ranging between the high 90s to around 103F across the lower
deserts. Further, albeit slight, day-to-day warming will continue
for Tuesday, as forecasted highs for lower elevation locations
will range between 100-105F.

Global model guidance indicates a weak, quick-moving shortwave
trough traversing the western CONUS by Wednesday. The best energy
with this disturbance will pass well off to our north, with the
greatest height falls/coldest air focused over the Pacific Northwest
and Northern Rockies. This system would provide very little in
the way of change/impacts across the region, except for perhaps a
degree or two decrease in temperatures as heights aloft drop
slightly. Regardless, surface to 500mb thickness values will
remain above climatological normals, suggesting that temperatures
will also remain above normal, with afternoon highs between
100-105F, even with the passage of the weak trough. 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
far western Imperial County where gusts could reach as high as 35
mph Wednesday and Thursday afternoons.

Model cluster analysis agrees that amplified ridging will reemerge
by the latter half of the upcoming weekend, pushing heights aloft up
once more, helping to keep temperatures hot across the region. NBM
temperature forecasts keep highs between 100-105F for both Saturday
and Sunday, with potentially further warming for the start of next
week. Clusters are not in complete agreement with how strong the
ridge may become, but the potential exists for the ridge to become
further amplified, which may result in the first 110F
temperatures this year for some areas. The 75th percentile of the
NBM has temperatures in Phoenix reaching that mark by next
Wednesday, but it is too early to say with confidence if
temperatures will reach that point by next week.

&&

.AVIATION...Updated at 1740Z.

South-Central Arizona including KPHX, KIWA, KSDL, KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns are expected through the TAF period.
Winds will overall favor light(<10 kts), diurnal tendencies with
periods of light and variable directions. A few typical afternoon
breezes gusting into the teens will be possible, while some gusts
upwards of 20 kts will be possible at KIPL this evening. Otherwise,
FEW-SCT passing high clouds this morning will give way to SKC
conditions by this evening.

&&

.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/RW
AVIATION...Smith
FIRE WEATHER...Young/Salerno