545
FXUS65 KPSR 281051
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
351 AM MST Sun Apr 28 2024

.SYNOPSIS...
Temperatures will return to seasonal levels today as hghts aloft
increase over the forecast area. An overall dry and benign weather
pattern will set up across the Desert Southwest this week with highs
rising back above normal by Monday and Tuesday. A weak trough will
pass through the Intermountain West mid-week resulting in breezy
conditions and a slight decrease in temperatures. Otherwise, warm
and dry conditions with no precipitation is anticipated through next
weekend.

&&

.DISCUSSION...
The upper level trough which brought gusty winds and much cooler
temperatures to our region over the past few days is now departing
eastward into the Southern Plains. 500 mb hghts will rise to around
572-575 dam today, allowing temperatures to return to seasonal norms
with highs reaching the upper 80s to near 90 across the lower deserts
of AZ and southeast CA. It will not be as breezy this afternoon with
winds remaining largely below 15 mph. Tranquil conditions will
continue through this evening and into tonight as lows fall into
the mid 50s to low 60s in most locations.

Heading into the beginning of the workweek, we will see a transition
to quasi-zonal flow aloft and a continued increase in mid-level
hghts/thicknesses over the forecast area. High temperatures are
expected to rise back above normal on Monday and Tuesday into the
lower to middle 90s for the lower desert communities. Very little
cloud cover is expected over the next several days as dry westerly
flow aloft prevails. It will also feel noticeably drier with
relative humidity falling below 15% each afternoon. By Wednesday,
a shortwave trough will begin to swing through the Intermountain
West, resulting in an increased 700-500 mb hght gradient and an
uptick in winds over southcentral AZ. Widespread breezy conditions
will return to the area Wednesday afternoon with gusts up to
20-25 mph possible. As the afomentioned trough dives across the
4-Corners region on Thursday, a backdoor front will enter the
Colorado River Valley, bringing gusty northerly winds. This front
will result in no sensible change to the temperatures however with
highs still expected to remain in the lower 90s across much of
the region.

Beyond Thursday, there is still a fair amount of disagreement
between global ensembles regarding the overall upper level pattern.
Some clusters show weak ridging building over the Desert Southwest,
whereas others indicated negative hght anomalies and continued
troughing over the western CONUS. This uncertainty is also apparent
within the spread between the NBM 25th-75th percentile temperatures
from Friday through Sunday with highs ranging anywhere from the
lower 90s to above 100 degrees in the Phoenix Metro. Despite these
discrepancies, there is an overall consensus from the ensembles
that we will see a dry pattern with no precipitation chances for
our region through at least next weekend.

&&

.AVIATION...Updated at 0510Z.

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

No significant weather issues will exist through Sunday night under
clear skies. Forecast confidence is excellent that winds around the
Phoenix area will switch to easterly around or after midnight, then
revert back to westerly slightly earlier than usual Sunday late
morning/early afternoon. Across SE California, a west component will
be the preferred direction with periods of nearly calm conditions
common. Gustiness will be very limited temporally and in magnitude
across the region.

&&

.FIRE WEATHER...
A warming trend will commence today with temperatures rising back to
near normal. Winds will be much lighter this afternoon and follow
typical upslope/downvalley patterns. A notable warming trend will
transpire through the middle of this week with lower desert highs
rising back into the low to mid 90s by Monday. Along with the warmer
temperatures, it will be consequently drier each afternoon with
minimum relative humidity values bottoming out around 8-15% over
the next several days. Moisture recovery will range from poor to
fair each night. Winds are expected to stay below 15 mph through
Tuesday, however there is potential for some increased breeziness
toward the middle to latter half of this week as a dry weather
system passes north of the area.

&&

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

$$

DISCUSSION...Salerno
AVIATION...18
FIRE WEATHER...Salerno