Winterhaven, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

769
FXUS65 KPSR 210823
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
123 AM MST Wed May 21 2025

.KEY MESSAGES...

1) Temperatures will continue to warm into Thursday with lower
desert highs topping 100 degrees today and likely peaking at
around 105 degrees on Thursday. Highs in the upper 90s to the
lower 100s are forecast for the Memorial Day weekend.

2) The hot temperatures will result in an overall Moderate
HeatRisk (Level 2) for today through Friday, posing an increased
risk to vulnerable populations.

3) Afternoon breeziness is expected Thursday and Friday, with the
strongest winds on Friday as gusts as high as 20-30 mph. Dry
conditions will continue to prevail through at least next week.

&&

.DISCUSSION...

Weather Pattern Overview:
Quasi-zonal dry westerly flow remains in place across the Western
U.S. with a flattening Pacific ridge still centered to our
southwest. H5 heights are gradually rising across the Desert
Southwest due to the influence of the Pacific ridge, despite the
overall zonal flow. Since yesterday H5 heights have risen from
around 582dm to around 584dm currently with guidance showing a
peak of between 586-588dm on Thursday. Heights of this magnitude
are not unusual for this time of year and typically yield daytime
highs anywhere from 5-10 degrees above normal. As heights rise
into Thursday, temperatures will get a further boost with NBM
forecast highs showing readings between 100-104 degrees today and
102-106 degrees on Thursday. These hot temperatures will result in
Moderate HeatRisk developing across much of the area.

Starting Thursday night into early Friday, a weak but quite large
upper level trough is forecast to move into California before
eventually sliding across our region on Saturday. This dry
disturbance will help to begin to lower heights aloft starting
Friday while also lowering daytime highs more into a 100-103
range. The incoming system will also help to increase winds with
gusts Friday afternoon likely in a 20-25 mph over most of the
area, but with the strongest winds of 30-35 mph possible Friday
evening across Imperial Co., CA. As the trough passes through the
region Saturday, it is likely to briefly drop high temperatures
back into the mid to upper 90s.

Model guidance is starting to come to a better consensus for what
to expect for Sunday and Monday with the potential weak cut-off
low solution mostly disappearing. Now ensembles mainly suggest a
weak ridge slowly passing through our region with some uncertainty
by next Tuesday and Wednesday with another possible dry system
approaching from the west. NBM temperatures have inched upward a
degree or so for both Sunday and Monday due to the clearer
guidance on the weak ridge, resulting in highs from the upper 90s
to the lower 100s. Beyond Monday, the uncertainty in the position
of the ridge and the incoming trough means lower forecast
confidence in temperatures going into the middle part of next
week.

Forecast Confidence & Deviations:
Confidence in the forecast guidance through the rest of the week
is quite good with decreasing confidence going into next week. The
only deviations from the NBM for this current package to increase
winds 10-20% across Imperial Co. Friday evening.

&&

.AVIATION...Updated at 0532Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No aviation concerns will exist through the TAF period. Winds will
generally follow diurnal trends, E`rly for the overnight period
and back W`rly by late tomorrow morning. Wind speeds generally AOB
10 kts, and more light/VRB winds at the northern terminals. Clear
skies will continue to persist.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns will exist through the TAF period. W`rly
winds will weaken at KIPL and shift to the SE by tomorrow
morning. VRB winds at KBLH for the overnight period also shift to
the SE by tomorrow morning. Wind speeds mostly be AOB 10kts at
both terminals, with speeds to picking at KBLH tomorrow afternoon
around 10-11kts. Clear skies will continue to persist.

&&

.FIRE WEATHER...
High pressure will continue to prevail through the rest of the
week with warming through Thursday. Above normal temperatures are
expected, with afternoon highs reaching the lower 100s across the
lower deserts starting today and lasting through Friday. Very dry
conditions are expected each day, with widespread MinRHs down to
5-12% and overnight recoveries to 15-30%. Light winds will
continue today before winds increase Thursday with gusts to
around 20 mph and even higher gusts of 20-30 mph possible on
Friday. This could bring another period of elevated fire weather
conditions on Friday. The dry conditions will continue over the
upcoming holiday weekend, but with diminishing winds and
temperatures running a few degrees above normal.

&&

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

$$

DISCUSSION...Kuhlman
AVIATION...Ryan
FIRE WEATHER...Kuhlman