Winterhaven, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

750
FXUS65 KPSR 112355
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
455 PM MST Mon Aug 11 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Above normal highs and warm overnight lows will continue to
  yield widespread Moderate to localized Major HeatRisk during the
  next couple of days.

- Major HeatRisk will be concentrated particularly over the
  central AZ lower deserts, the Lower Colorado River Valley, and
  Imperial Valley where Extreme Heat Warnings remain in effect
  through Tuesday evening.

- Isolated to widely scattered showers and thunderstorms will be
  possible across the higher terrain east of Phoenix through mid-
  week.

- Increasing moisture late week will result in better coverage of
  thunderstorm activity across much of the region including the
  lower deserts.

&&

.SHORT TERM /Today through Tuesday/...
The latest objective analysis shows an elongated upper-ridge
centered across northern CA. This is resulting a northerly
steering flow across much of the region. This northerly flow is
bringing in some drier air, which will persist through midweek,
causing PWATs to drop under 1.2". Therefore, storm activity will
mostly be limited across the higher terrain areas of eastern and
southeastern AZ during the next couple of days with the lower
deserts expected to remain dry as the drier air will continue to
result in strong convective inhibition. In terms of any potential
outflows reaching the lower deserts from the higher terrain
activity, the latest HREF indicates a low probability, 10-30%, of
occurrence with gusts exceeding 35 mph during the next couple of
days.

Otherwise, the main story during the next couple of days will be the
heat. The aforementioned high pressure will result in 500 mb height
fields to range between 592-594dm, translating to afternoon highs
ranging between 108-115 degrees across the lower deserts, with the
highest temperatures expected across southeast CA. Temperatures of
this magnitude combined with above normal lows will continue to
result in widespread Moderate to locally Major HeatRisk. The Major
HeatRisk will continue to be concentrated across the lower deserts
of south-central AZ as well as across the Lower Colorado River
Valley and Imperial Valley with Extreme Heat Warnings in effect
through Tuesday evening.

&&

.LONG TERM /Wednesday through Sunday/...
Beginning on Wednesday, ensemble guidance continues to indicate a
trough of low pressure entering the Pacific Northwest while the
subtropical high centered over the Great Basin begins to weaken and
shifts eastward toward the Four Corners area. This shift in location
of the high will establish NE mid-lvl flow over the forecast area
and potentially bring any storms that form over the Mogollon Rim
into the lower deserts. The main limiting factor will be moisture
availability with PWATs only rising to around 1.2-1.3" by Wednesday
afternoon. Right now NBM PoPs are around 30-40% across the high
terrain and up to 20% for the lower deserts Wednesday afternoon
and evening. As hghts aloft begin to decrease on Wednesday, high
temperatures will cool by a degree or two, however many lower
desert communities including Phoenix, Yuma, and El Centro are
still forecast to reach the 110 degree mark.

Heading through the latter half of this week and into this weekend,
ensemble and deterministic model guidance continue to indicate
the aforementioned trough of low pressure over the Pacific NW will
become more amplified off the coast of CA while the subtropical
high migrates into the Southern Plains. As this occurs, there will
be a better opportunity for deeper moisture to be pulled into
southern AZ. However, it is important to note that there is still
quite a bit of disagreement between the EPS and GEFS regarding the
magnitude of moisture return. The EPS is continuing to indicate
better moisture return with PWATs rising to around 1.5-1.6" on
Thursday and Friday, whereas the GEFS is only showing PWAT values
maxing out around 1.3-1.4". This discrepancy is likely due to the
strength and positing of the trough to our west. Despite these
differences, NBM PoPs have not changed much and are still hovering
around 30-40% across the lower deserts and up to 50-60% across
the high terrain of southcentral AZ both Thursday and Friday. Due
to the presence of the trough and uptick in moisture, temperatures
will decrease to near normal with highs topping out around
100-107 degrees across the lower deserts Thursday and Friday.

By this weekend, drier air associated with troughing to our west
will begin to overspread our region, resulting in much more
limited thunderstorm activity across the state. Although we will
see a drying trend, the troughing pattern over the western U.S.
will help keep 500 mb hghts suppressed and thus we will continue
to see temperatures near seasonal norms through Sunday.

&&

.AVIATION...Updated at 2355Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:

No major aviation weather concerns are expected through the TAF
period. Winds will tend to follow typical diurnal patterns
through the TAF period with afternoon gusts around 20-25 kts
persisting into the early evening hours. May see a push of
southwest winds this evening that could keep wind speeds elevated
through midnight before subsiding. Skies will remain mostly clear
the bulk of the period with any clouds at or above 15K feet. All
storm activity will stick to the high terrain with no outflows
expected.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns are expected over the next 24 hours
under generally clear skies. Winds at KIPL will remain out of the
east-southeast through this evening before a period of westerly
sundowner winds between 02-09Z, while KBLH will continue to see
more southerly to south-southwesterly winds, gusting upwards of
20-25 kts at times into this evening.

&&

.FIRE WEATHER...
Above normal temperatures will continue through the middle of this
week but increasing moisture will result in a cool down to near
normal temperatures by the end of the week. Chances of wetting
rainfall will remain below 10% through Tuesday, resulting in
potential for dry lightning and new fire starts. During the
Wednesday through Friday time period, the CWR will increase to
around 20-30% across the AZ high terrain. Minimum afternoon
humidity levels will mostly range between 15-20% each afternoon with
fair to good overnight recovery anticipated. Winds will continue
to follow normal diurnal patterns (afternoon upslope followed by
downvalley overnight) with afternoon gusts to 15-20 mph common.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Tuesday for AZZ530-532-534-
     537>544-546-548>551-553>555-559.

CA...Extreme Heat Warning until 8 PM PDT Tuesday for CAZ562-563-566-
     567-569-570.

&&

$$

SHORT TERM...Lojero
LONG TERM...Salerno
AVIATION...Smith/Benedict
FIRE WEATHER...Salerno