Chiriaco Summit, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

786
FXUS65 KPSR 040542
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1040 PM MST Sat May 3 2025

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
A potent low pressure system will enter the Desert Southwest
resulting in breezy to locally windy conditions focused over
Southeast California this evening, then areawide Sunday. Scattered
showers and isolated thunderstorms will be possible across portions
of the area on Sunday. Lingering chances for showers will continue
Monday and possibly Tuesday mainly across the Arizona higher
terrain. Below normal temperatures will persist through Tuesday
followed by a quick warmup during the latter half of next week.

&&

.DISCUSSION...
Early afternoon mid-level water vapor imagery reveals a ridge
positioned over the Intermountain West, the influence of which our
area still falls under, and a deep trough just off the West Coast. A
weak cutoff low still lingers over AZ, helping to spark some
convective showers mainly over the northern AZ high terrain this
afternoon, though this low will have little influence on thermal
profiles over the lower deserts. As such, we`ll see one more day
with temperatures slightly above seasonal normals, reaching the
lower to middle 90s across the lower deserts.

The upper level trough off the West Coast will become a closed low
over the next 24 hours or so, as it makes its way onshore over SoCal
tonight into early Sunday morning. The increasing gradient aloft
ahead of the low as it follows this trajectory will allow for strong
winds to develop at the surface over the typical wind prone areas of
SE CA this evening and through the overnight hours, particularly
Western Imperial County. Therefore, a Wind Advisory remains in
effect for that area starting 5 PM PDT this afternoon. By Sunday
afternoon, the strongest winds aloft will have shifted east of the
forecast area, though some near Advisory-level gusts between 30-40
mph will be possible, especially along ridgetops, to the
east/southeast of the Phoenix Area. These windy conditions may
result in patchy areas of blowing dust across central Pinal County
during the afternoon into the early evening hours.

Aside from breezy to locally windy conditions, the strong dynamics
of this upper low and modest northward moisture transport, mostly in
the mid-levels, will result in the development of scattered showers
and isolated thunderstorms Sunday afternoon into the evening. NAEFS
mean PWAT values increase to just upwards of 0.75", which is in
excess of the 90th percentile of climatology for the time of year.
Additionally, latest HREF mean MUCAPE reflects the increase in
moisture and steepening lapse rates as the core of the low moves
overhead, with a corridor of values upwards of 250-500 J/kg
stretching from Western Maricopa into La Paz and Eastern Riverside
Counties. This setup should support scattered coverage of convective
showers, with a few thunderstorms capable of producing gusty outflow
winds and pea sized hail. Rainfall amounts Sunday are not expected
to be very high with most areas actually seeing rain receiving less
than a tenth of an inch, but very localized areas may see up to
around 0.25-0.50" from any thunderstorms.

Much cooler air will also move into the area on Sunday as a cold
front pushes through during the morning hours. Forecast highs Sunday
are only in the upper 70s to around 80 degrees across the lower
deserts with Monday`s readings even a few degrees cooler. The upper
level low will be slow to exit the region early next week as a
secondary shortwave is expected to dive southward down the backside
of the low late Monday into Monday night. With the center of the low
remaining in place on Monday and moisture staying elevated, some
areas could see another round of isolated to scattered light showers
with the best chances likely across eastern Riverside and La Paz
Counties, and over the higher terrain north and northeast of
Phoenix. Tuesday may also bring some higher terrain showers, but the
bulk of the activity will stay outside of our area. As the upper low
continues to weaken and fill over our region going into the middle
of the workweek, temperatures will begin to climb as highs warm back
into the mid to upper 80s on Wednesday. This warming trend will
continue through the latter half of the workweek, especially
Thursday into Friday as a ridge moves back over our region. This
should easily push daytime highs well into the 90s with some areas
even flirting with 100 degrees by next Friday. Ensemble guidance
even suggests we may see highs top 100 degrees for next weekend.

&&

.AVIATION...Updated at 0540Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
The greatest weather impacts will be concentrated on Sunday
afternoon and evening in the form of several hours of gusty,
southerly cross runway winds followed by scattered late
afternoon/evening SHRA/TSRA with the potential for erratic wind
directions, periodic cigs developing in a 5-7K ft range, and lofted
BLDU impacting slantwise visibility. This evening, W/SW winds with
gusts around 20kt will continue before weakening and trending more
towards the SE overnight. Several hours of a southerly cross cross
runway wind with gusts 20-25kt appear likely Sunday mid/late morning
through early afternoon before veering to SW by mid afternoon. Wind
directions may become extremely erratic late afternoon and evening
around any scattered SHRA/TSRA.

Very low confidence will exist for much of Sunday due to a complex
weather pattern and local loss of important model guidance. There
may be a period of at least SCT decks 040-060 during parts of the
morning, but more likely lower cig development will be delayed until
mid/late the afternoon. Wind directions should veer more SW by mid
afternoon, but may retain some 160v240 with gusts 20-25kt. TCU/SHRA
should build during the late afternoon with low confidence on timing
and proximity to the terminals, however direct impacts from SHRA,
cigs below 060, and/or gusty erratic outflow winds are becoming more
likely with latest model guidance. A 30% chance of embedded TSRA
exists and was introduced in this TAF package. Confidence is
somewhat better that more concentrated scattered SHRA and lowering
cigs will sweep through the PHX metro Sunday evening.


Southeast California/Southwest Arizona including KIPL and KBLH:
Strong gusty winds will be the main weather impact at KIPL through
Sunday evening while the chance for SHRA/TSRA will be the greatest
potential impact at KBLH. Winds should maintain a westerly component
at KIPL through the period with good confidence of gusts 25-35kt
through the overnight with some modest weakening later Sunday
morning. S/SW winds will not be as pronounced at KBLH, yet still
occasionally gust 20-25kt. Confidence is moderate that SHRA/TSRA
with very erratic winds will form in the vicinity of the terminal
late Sunday afternoon. SHRA and variable wind directions may
persist well into Sunday night.

&&

.FIRE WEATHER...
A strong weather system will promote a substantial cool down from
Sunday into early next week. The approaching weather system will
result in increased winds across the Imperial Valley and Lower
Colorado River Valley this afternoon and evening. On Sunday,
elevated conditions will shift eastward to the AZ high terrain where
gusts could reach 30-40 mph. However, MinRHs will improve areawide
to around 20% by Sunday afternoon. There will be a slight chance for
showers and thunderstorms in southcentral AZ on Sunday, however the
chances for wetting rainfall remains low (<20%). Any storm that
develops will be capable of producing gusty and erratic winds.
Chances for showers will linger across the AZ high terrain through
early Tuesday. High pressure will likely to move back over the
region by the middle to latter half of next week, leading to warmer
and drier conditions.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 2 AM PDT Monday for CAZ562.

     Wind Advisory until 5 AM PDT Sunday for CAZ566-567.

&&

$$

DISCUSSION...Whittock/Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman