137
FXUS65 KPSR 072010
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
110 PM MST Thu May 7 2026

.KEY MESSAGES...

- A pronounced warming trend will continue this week resulting
in a period of well above normal temperatures.

- Widespread moderate HeatRisk will develop over the weekend with
isolated major HeatRisk early next week.

- Monday should be the warmest day next week with lower desert high
temperatures peaking between 105 and 110 degrees.

&&

.SHORT TERM /Today through Saturday/...
An innocuous, moisture starved closed low and vorticity center
continues to propagate across northern Sonora early this afternoon
as pronounced East Pacific ridging slowly builds towards the SW
Conus. The former feature has restricted more rapid warming with H5
heights holding in a 574-578dm range, while the latter will boost
heights above 582dm by the weekend resulting in a marked increase in
temperatures. Ensemble numerical spread is extremely narrow yielding
excellent forecast confidence of daily highs reaching around 10F
above normal Friday, then 10F-15F above normal Saturday. Given the
very dry airmass in place, nocturnal cooling will be far more
efficient with morning lows only a few degrees above normal.
Otherwise, strong high pressure ridging will preclude any rainfall
chances, much less appreciable cloud cover.

&&

.LONG TERM /Sunday through Thursday/...
As ridging fully envelops the Southwestern U.S. this weekend, H5
heights are projected to rise even further reaching 585-588dm on
Sunday before peaking as high as 589-591dm Monday. The strength of
this ridge would fall around 97-99% of climatological records for
the period likely nearing high temperature thresholds.

As peak heights occur on Monday, temperatures are forecast to rise
to 105-110 degrees out west to 104-108 degrees around the Phoenix
metro. For this time of year, this would result in daytime max
temperatures in a major HeatRisk category, but overnight lows will
still be quite mild (minor HeatRisk). As a result, the total
HeatRisk mostly falls within the (high-end) moderate category, but
with localized major areas on Monday. Ensemble probabilities of
major HeatRisk are sufficient through western Imperial County to
justify an Extreme Heat Watch Sunday and Monday. Other
considerations were given to the Phoenix metro, however the limited
areal expanse of major HeatRisk temporally limited to Monday, along
with cooler overnight lows and fact that the region has already
experienced prolonged, anomalously warm temperatures above 100F this
season are arguments against heat headlines. However, if forecast
temperatures (particularly low temperatures) increase a few more
degrees, headlines may become necessary.

Models mostly favor a slight decrease in heights going into the
middle of next week, largely due to a weak cut-off low that is
likely to develop west of Baja before moving northward along the
coast of California. This should begin a slow cooling trend starting
next Tuesday, but the above normal temperatures are expected to
persist through the rest of next week.

&&

.AVIATION...Updated at 1748Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns are expected during the TAF
period. Winds will follow typical diurnal trends through the period,
with speeds aob 10 kts. Skies will be mostly clear with the
exception of a few passing cirrus this afternoon/evening.


Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns are expected during the TAF
period. Outside of periods of VRB to calm conditions this morning,
winds at KIPL will be between W and NNW, while at KBLH winds will be
primarily westerly, and slowly shifting SSW near the end of the
period. Skies are expected to remain clear.

&&

.FIRE WEATHER...
High pressure building into the region will lead to much warmer
temperatures and continued low RHs into the weekend. Highs will
reach well into the 90s today before topping 100 degrees by Friday
or Saturday. Expect MinRHs from 7-12% each day through at least the
weekend. Winds will remain relatively light for much of the period,
but some afternoon breeziness with gusts to around 20 mph is likely.
The combination of the very low RHs and breezy conditions likely
focused during the late afternoon hours on Friday and Saturday may
result in elevated fire weather conditions for portions of the area.
Hot and dry conditions will continue to prevail into next week with
afternoon breeziness and elevated fire weather conditions still a
possibility each day.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Extreme Heat Watch from Sunday morning through Monday evening
     for CAZ562-563-566.

&&

$$

SHORT TERM...18
LONG TERM...18/Kuhlman
AVIATION...Ryan
FIRE WEATHER...Kuhlman

NWS Phoenix (PSR) Office