Glamis, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

577
FXUS65 KPSR 180535
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1035 PM MST Sat May 17 2025

.UPDATE...Updated 06Z Aviation Discussion.

&&

.KEY MESSAGES...

1) Gusty winds of 30-50 mph expected (>80%) today with Wind
advisories for Imperial County extending to the Arizona border.
Gusts of 25-35 mph likely (60-80%) Monday, focused on the Lower
Colorado River Valley and higher terrain.

2) Substantial warming trend expected (>80%) next week, with
highs of 102-107F and widespread Moderate HeatRisk (Level 2)
likely (60-80%) Wednesday-Friday, posing risks to vulnerable
populations.

3) Low humidity (10-15%) and gusty winds increase fire weather
risks today and Monday, with a 60-80% chance of elevated fire
danger in southeast California and western Arizona; avoid spark-
generating activities.

&&

.DISCUSSION...

Weather Pattern Overview: The Southwestern U.S. remains under
broad troughing, with a strong shortwave tracking southeastward
from northern California into Nevada this morning, reaching
northern Arizona this afternoon and evening. Strong height falls
will drive gusty winds of 30-50 mph across the region, with gusts
of 40-50 mph expected (>80%) in western Imperial County this
evening. Wind Advisories are in effect: covering portions of
southeast California to the Arizona border. A dry cold front will
traverse the area this evening, cooling temperatures slightly for
Sunday. Relative humidity of 10-15% is expected (>80%) this
afternoon, increasing fire spread potential, with a 60-80% chance
of elevated fire danger in Imperial County and western Arizona.

Sunday will be the most comfortable day of the week, with clear
skies expected (>80%), highs of 85-90F (~5F below normal), and
breezy conditions (20-25 mph gusts likely, 60-80%). A stronger
shortwave will dive through the Great Basin Sunday night, passing
northeast Arizona Monday daytime. This disturbance, shifted north
and east, will bring north-northwest gusts of 25-35 mph expected
(>80%) to the Lower Colorado River Valley and Arizona higher
terrain (e.g., Flagstaff, Prescott), with a 30-50% chance of 20-30
mph gusts in Phoenix. Relative humidity of 10-15% is likely
(60-80%), with a 50-70% chance of elevated fire danger.
Temperatures return to normal (90-95F in Phoenix, 93-97F in
Yuma) as a strong Pacific ridge approaches the California coast.

The Pacific ridge will spread over the region Tuesday, boosting H5
heights to 582-584 dm. Heights peak at 588-590 dm (90th
percentile) Thursday and Friday, driving highs of 100-104F
expected (>80%) Wednesday and 102-107F expected (>80%) Thursday-
Friday across Phoenix, Yuma, and El Centro. These temperatures,
10-15F above normal, have a 30-50% chance of approaching daily
records (e.g., Phoenix ~110F). Lows of 75-80F are likely
(60-80%), with relative humidity of 5-10% expected (>80%),
exacerbating heat stress. Moderate HeatRisk (Level 2) is expected
(>80%) Wednesday-Friday for lower deserts, posing risks to the
elderly, children, and outdoor workers, with a 30-50% chance of
Major HeatRisk (Level 3) in Yuma and Imperial County if highs
exceed 105F. GEFS and ECMWF ensembles show 80-90% agreement on
highs 100F, with a 20-40% chance of 1-3F higher temperatures if
the ridge amplifies.

Model uncertainty increases for Memorial Day weekend (May 24-26).
GEFS and ECMWF ensembles (60-70% of members) favor ridge
flattening, with highs of 98-102F likely (60-80%) in Phoenix and
100-104F in Yuma/El Centro. A 30-50% chance exists for 103-105F
if the ridge persists, while a 20-40% chance of cooler highs
(95-98F) depends on trough development (30-40% of GEFS members).
Minor to Moderate HeatRisk (Level 1-2) is likely (60-80%), with
dry conditions expected (>80%) and no significant precipitation
chance (<10%). Ensemble spread is 5F, with ECMWF slightly
warmer.

Forecast Confidence & Deviations: Confidence is high (>80%) for
weekend temperatures and winds, with improving confidence (70-80%)
early next week as models align on the shortwaves northern track.
Mid-week heat forecasts are robust (80-90%), with possible 1-3F
upward adjustments (20-40% chance), especially for Memorial Day
weekend depending on ridge evolution. Monitor HRRR for Saturday
evening wind/dust verification and ASOS/AWOS data for gusts, which
have a 20-40% chance of exceeding 50 mph in Imperial County.

&&

.AVIATION...Updated at 0533Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Gusty west winds will be the main aviation weather issue through
the TAF period. Gusts are starting to calm in the metro but could
still experience brief gusts through tonight. Winds pick back up
tomorrow afternoon with gusts between 20-22kts. W`rly winds are
maintained throughout the TAF period as low confidence continues
if an E`rly shift tomorrow morning will occur. Clear skies
throughout the TAF period.


Southeast California/Southwest Arizona including KIPL and KBLH:
Lingering gusty winds with reduced visibilities due to blowing
dust will be the main aviation weather issues. Gusts are expected
to subside by 08Z but maintain elevated sustained speeds
(especially at KIPL) at around 15kts. Winds are expected to
mainly be from the W-NW at KIPL and KBLH shifts between SW to NW
throughout the TAF period. Clear skies throughout the TAF period.

&&

.FIRE WEATHER...
Gusty winds and low humidity will drive elevated fire danger,
particularly in Imperial County, southeast California to the
Arizona border. This afternoon, model soundings indicate 925 hPa
winds of 2535 kt, yielding surface gusts of 4050 mph expected
(>80%) in western Imperial County and 3040 mph expected (>80%)
across southeast California. Surface RH of 1012% is expected
(>80%) by 15Z21Z, per HRRR and sounding data, with fuel moisture
at 810%. This combination results in a 6080% chance of elevated
fire danger, with fire spread rates exceeding 1 mile/hour in dry
grass. Poor overnight RH recovery of 2050% is expected (>80%).

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 2 AM PDT Sunday for CAZ563>567.

     Wind Advisory until 7 AM PDT Sunday for CAZ562.

&&

$$

DISCUSSION...95/Kuhlman
AVIATION...Ryan
FIRE WEATHER...95