701
FXUS65 KPSR 072309
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
409 PM MST Sat Jun 7 2025

.UPDATE...Updated 00z Aviation Discussion...

&&

.DISCUSSION...

KEY MESSAGES:

- Dry conditions through the period with temperatures peaking
upwards of 10 degrees above normal early next week

- Widespread moderate HeatRisk during the first half of next week
relaxing later in the week

Early afternoon WV imagery shows the formative stages of Rex
blocking across western North America with high amplitude ridging
extending into northern British Columbia while the trapped cutoff
low spins aimlessly off the central California coast. Concurrently,
subtropical high pressure has been strengthening over S Texas/N
Mexico with retrogressive tendencies battling against the basal,
westerly flow of the upstream block. These features will essentially
stall over the next 48 hours with currently analyzed H5 heights
in a 586-590dm range remaining nearly constant over the next 48
hours. Intense June insolation will steadily warm the lower
troposphere such that surface readings fall just outside a
persistence forecast, and forecast confidence is excellent that
temperatures will peak 5F- 10F above normal the next several days.
NBM forecasts remain consistent in advertising the warmest
readings across SE California where odds of hitting 110F remain
well above 50% for many lower elevation communities, while odds
around most of the Phoenix metro hover below 50%.

During the latter half of next week, the hemispheric flow pattern
will attempt to become more progressive with western Conus blocking
deamplifying and relaxing and strong Pacific jet energy carving out
mean longwave troughing over the NE Pacific basin. Ensemble suites
remain very uncertain with respect to the depth and orientation of
negative height anomalies off the Pacific NW coast, as well as the
interaction with the nearly stationary downstream subtropical ridge.
A growing contingent of GEFS members are less pronounced with the
depth and proximity of this trough to the Great Basin, and as a
result, suggest the subtropical anti-cyclone center more intense and
closer to the CWA with H5 heights only marginally dipping below
588dm. Several CMC and EC members also seem to be trending in this
direction, though the number of members not as prolific as the GEFS
collection. While some very minor cooling still appears likely late
in the week, not surprisingly, mandated NBM forecasts have decreased
the amount of cooling several degrees with readings solidly remain
above the seasonal normal. Though outside the time frame of this
forecast package, there is mounting evidence of 595dm (or greater)
H5 heights developing somewhere in the region next weekend -
possibly overhead, but more likely towards New Mexico or the four
corners. This scenario could yield the first bout of extreme heat
for parts of the forecast area during the middle of the month.

&&

.AVIATION...Updated at 2305Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No aviation weather concerns under clear skies are expected
throughout the TAF period. The overall wind pattern will continue
to exhibit the typical diurnal tendency with speeds aob 10 kts.
Periods of light and variable winds are likely as well, especially
during the transition periods.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns under clear skies are expected
throughout the TAF period. Winds at KIPL will transition out of
the west for a period of time this evening before transitioning
back out of the southeast during the overnight hours. Winds at
KBLH will fluctuate between the southeast and southwest. Overall
wind speeds will remain aob 10 kts. Periods of light and variable
winds are likely as well.

&&

.FIRE WEATHER...
Above normal temperatures will be common through much of next week
with the warmest period early in the week. Recent moisture
availability has largely been scoured from the districts with
minimum afternoon RHs will falling near 10% (more prevalent single
digit RH`s occurring tomorrow and Monday). This will be accompanied
by poor to fair overnight recovery of 20-40%. Winds should follow
fairly typical late spring cycles with periods afternoon upslope
gustiness. Somewhat more breezy conditions may arrive to the region
towards the end of next week resulting in a slightly elevated fire
danger.

&&

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

$$

DISCUSSION...18
AVIATION...Lojero
FIRE WEATHER...Ryan/18