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325
FXUS65 KPSR 231022
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
322 AM MST Sun Jun 23 2024

.SYNOPSIS...
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Daily shower and thunderstorm chances will continue through early
this week, with most activity confined to the higher terrain areas
across southcentral Arizona. Cloudy conditions will persist
through at least today, which will keep temperatures a few degrees
cooler relative to the middle of this week, where highs will climb
several degrees above normal.
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&&

.DISCUSSION...
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Mid to high level moisture and clouds continue to stream in from
the southwest this morning, resulting in some scattered shower
activity according to the latest MRMS radar returns. Specifically
to southcentral Arizona, scattered showers are moving
northeastward across Gila County, with a more solid area of
showers moving into southern Maricopa County. Hi-res guidance
suggest these showers, especially in southern Maricopa and western
Pinal Counties to continue over the next several hours. After
these showers dissipate, attention turns towards afternoon/evening
convective activity once again. The highest chances again will be
focused over higher terrain areas, as cloud cover will continue
to be a limiting factor in potential/strength today as well as the
mean mid-level flow turns more southwesterly. Further west across
southwestern AZ and even into SE CA, less cloud coverage could
spark a few showers and storms as the elevated moisture levels
(and in turn more instability) will reach that region of the
forecast area today. General expectations for showers/storms are
around 30-40% (10-20%) for the higher terrain of southcentral AZ
(southcentral & southwestern AZ as well as southeastern CA). HREF
wind potential for 35+ mph for any outflows is much lower today,
generally 10-30% centered across southcentral and southwestern AZ
this afternoon and evening.

Ridging/surface high pressure will continue to migrate westward
going into tomorrow, continuing the downward trend for convective
activity, mainly due to strengthening subsidence aloft from the
building mid-level heights. This ridging feature will persist
through the middle of the week, resulting in a warming trend, as
mid-level heights hover in the 591-594 dam range. Widespread
Moderate HeatRisk will persist during this period, while localized
Major HeatRisk develop Tuesday through Thursday. While moisture
levels will remain elevated during this period (general consensus
is 1.75"-2.00" through Tuesday), thunderstorm chances will
diminish, especially for lower desert locations beginning
tomorrow. Thus, expect daily thunderstorm chances to reside mainly
in the higher terrain areas of southcentral Arizona going through
most of this week.

Looking towards the extended period, ensemble clustering shows
excellent agreement through at least Thursday, as a troughing
feature moves into the Pacific Northwest. As this trough traverses
across the Intermountain West going into this upcoming weekend,
mid-level heights will fall by a few decameters, resulting in a
slight cooling trend. More noticeable spread is seen in the
clusters by this upcoming weekend, where there is some uncertainty
in how quickly this trough exits the region and how quickly
heights build in from the east again. This will affect if and how
quickly temperatures may warm going through this upcoming weekend,
as current NBM temperature spreads are around 5-8 degrees for the
interquartile ranges for central Phoenix Saturday and Sunday.
Ensembles continue to show elevated moisture levels during the
extended period, thus while HeatRisk may remain mainly in the
Moderate category, higher humidity levels should still be
accounted for any outdoor plans during this period.
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&&

.AVIATION...
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Updated at 0520Z.

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

Outflow originating from Yavapai County is overspreading the metro
area with N/NEly winds. Peak gusts have been in the 20-25kt range
but short lived. An exception is KPHX with weaker winds that are
favoring Ely/NEly directions. As the outflow dissipates, light and
variable winds will develop by 10Z or so. Anticipate light and
variable winds for much of the day Sunday. Storm activity is
anticipated to be limited to the higher terrain except perhaps for
portions of La Paz County and far northern Yuma County. Westerly
outflow from there may reach the Valley Sunday evening. As for sky
cover, considerable mid and high cloudiness will wax and wane
during the forecast period with ceilings getting as low as FL120
but mainly AOA FL150. Weak and short lived isolated showers can`t
be ruled out but would be of little consequence.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds at IPL are expected to be out of the SE through the TAF
period with speeds mainly under 8kts tonight into the morning
before picking up a little bit in the afternoon. At KBLH,
directions will favor south early in the forecast period before
becoming light and variable overnight. Minor southerly breeziness
(gusts to 20kts) resumes by midday Sunday. One caveat is that
storms may develop over/near the Kofa mountains which in turn
could create gustiness from the east/southeast by late
afternoon/early evening. As for sky cover, anticipate a gradual
increase of mid and high clouds (mainly AOA FL150) tonight and
linger through Sunday.
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&&

.FIRE WEATHER...
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Monsoonal moisture will continue to result in daily chances for
shower and thunderstorm activity, with the best chances for
activity across the higher terrain areas. With the elevated
moisture in place, MinRH values through early this week will
range between 35-45% across the far eastern districts to between
15-25% across the western districts before slowly drying into the
middle to latter half of next week. Winds will follow their
typical daily tendencies, with gusty outflows from any
thunderstorm activity anticipated over the next several days.
Temperatures through the weekend will average near to slightly
above normal before increasing some heading into the middle of
next week. Chances for wetting rains will generally remain around
15-25% for the higher terrain areas and 5-10% for the lower
deserts of southcentral Arizona through tomorrow.
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&&

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

$$

DISCUSSION...Young
AVIATION...AJ
FIRE WEATHER...Young/Lojero