691
FXUS65 KPSR 120534
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1034 PM MST Sun May 11 2025

.UPDATE...
06Z Aviation Discussion.

&&

.SYNOPSIS...
Temperatures will cool through the middle of the week as a dry
weather system moves into the region. Associated with this weather
disturbance, gusty winds will be common the next several days.
Temperatures should slowly rebound during the latter half of the
week eventually hovering around the seasonal normals.

&&

.DISCUSSION...
A blocking pattern which has predominated the Conus will slowly open
over the next several days as a series of progressive Pacific
disturbances and strong jet energy dislodge cutoff negative height
anomalies across the lower Mississippi River valley. H5 heights near
585dm over the SW Conus which have supported temperatures some 10F
above normal will gradually erode closer to 572dm over the next 72
hours as modest height falls enter the region. While the primary
cold core/circulation center and strongest forcing will remain north
of the forecast area, sufficient jet energy and higher momentum
within a seasonally deep mixing depth will result in periodically
gusty winds early in the week. With models depicting 25-35kt winds
developing in a H8-H7 layer corresponding to the incoming height
falls and weakening frontal boundary, confidence is very good that
enhanced gusts will impacts much of the region beginning in SE
California Monday, then migrating eastward Tuesday. An enhanced fire
danger and localized blowing dust may be the most significant
hazards with this weather system passage.

Although the Conus pattern will remain slowly progressive during the
latter half of the week, some measure of broad cyclonic, or quasi-
zonal flow will settle over the Southwest. As such, forecast
confidence is good that H5 heights should hover in a 576-579dm range
with the pattern configuration prohibiting significant height rises
or rapid warming. Instead, narrow guidance spread suggests readings
returning to a near normal mid-May level persisting into the
weekend. Ensemble spread starts growing notably towards the end of
the period as membership is split between maintaining negative
height anomalies over the SW Conus, or shifting mean troughing into
the eastern Conus and allowing broad ridging to materialize over the
forecast area. CMC members remain the most amplified with negative
anomalies centered over the forecast area with trends in GEFS
membership pointing towards higher probabilities of amplified
heights and/or flat ridging. At this time, these disparate solutions
form an ensemble mean not far from a typical, dry quasi-zonal May
pattern.

&&

.AVIATION...Updated at 0530Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No aviation concerns are anticipated through the forecast period.
Winds will remain light, aob 7 kts overnight with the exception of
KIWA where winds will be slightly more elevated around 11 kts.
Expect an easterly shift at KPHX by 09Z. Winds will increase out
of the S-SE after sunrise tomorrow morning, resulting in a
southerly cross-runway component at KPHX for approx 3-4 hours
before ultimately shifting out of the SW by the early afternoon.
Gusts between 20-25 kts will be common from the late afternoon
through the early evening at all terminals. High clouds will
continue to overspread the region tonight and into tomorrow with
bases remaining aoa 15 kft AGL.

Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty winds and the potential for blowing dust will be the primary
aviation concerns at the southeast CA terminals, especially by
tomorrow afternoon and evening. Winds will remain westerly at KIPL
and southerly to southwesterly at KBLH through the period. Expect
speeds to be elevated around 10-15 kts overnight. By early
tomorrow morning, gusts will materialize at both terminals,
reaching 25-30 kts at times. Stronger gustst into the 30-35 kt
range will be possible at both sites by tomorrow afternoon which
could lead to periods of reduced vsby due to blowing dust. High
clouds will continue to overspread the region with bases remaining
aoa 18 kft AGL.

&&

.FIRE WEATHER...
An elevated fire danger will exist Monday and Tuesday as warm
temperatures, low humidity levels, and gusty winds become juxtaposed
with receptive, dry fine fuels. Afternoon humidity levels in the
teens will be common throughout the week following poor to fair
overnight recovery of 20-50%. Wind should be strongest Monday and
Tuesday with gusts 25-35 mph during the afternoon and early evening.
Gusts will likely be most pronounced across ridge tops and in the
typical downsloping areas. Speeds should weaken during the latter
half of the week, though still will retain the usual upslope
gustiness. Temperatures will also cool during the middle of the week
as the weather system moves into the region, however should rebound
closer to the seasonal normal by the end of the week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory from 5 AM Monday to 5 AM PDT Wednesday for CAZ562.

&&

$$

DISCUSSION...18
AVIATION...Salerno
FIRE WEATHER...18