603 
FXUS65 KPSR 280537
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1037 PM MST Sat Sep 27 2025

.UPDATE...06Z Aviation Discussion.

&&

.KEY MESSAGES...

- Shower and thunderstorm activity will continue to affect 
  portions of southwest Arizona and southeast California with more
  isolated activity across south-central Arizona through this 
  evening. 

- A drier and much quieter weather pattern will settle across the
  region beginning on Sunday.

- Below normal temperatures will prevail through the weekend 
  before gradually warming up to near normal by the middle of next
  week.

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...
The upper-level low pressure system that has been causing impactful 
weather during the last couple of days remains situated near 
southeast CA as of early this afternoon. Along the eastern flank of 
the low, shower and thunderstorm activity have erupted across 
portions of southeast CA and southwest AZ, with activity expected to 
continue across these through this evening before eventually 
dissipating completely. With MLCAPE values ranging between 500-1000 
J/KG along with PWATs between 1.2-1.5", the environment will remain 
favorable for some stronger storms capable of producing heavy 
rainfall amounts in excess of 1-2" in a short amount of time. Thus, 
the flash flood potential will remain elevated with a Flood Watch in 
effect through early this evening. Farther east, across south-
central AZ, the shower and thunderstorm activity will remain more 
isolated in coverage and thus not nearly as impactful as yesterday's 
activity where widespread flash flooding was observed. Nevertheless, 
any storms that do move across will be capable of producing brief 
heavy downpours but the quick residence time should limit rainfall 
amounts. 

Heading into Sunday, the upper-level low will finally weaken and 
move eastward through central AZ and thus most of the region will 
remain on the subsident side. Therefore, thunderstorm activity will 
be much more limited in coverage with chances mainly across the 
AZ high terrain and any terrain escarpments through the afternoon 
before rain chances end completely by the evening hours. 

&&

.LONG TERM /MONDAY THROUGH FRIDAY/... 
By Sunday night into Monday, our region will transition more into 
zonal flow to weak ridging as a deep Pacific low moves southward to 
off the Pacific Northwest coast. Temperatures will remain 5-8 
degrees below normal areawide this weekend with the help of the 
cutoff low over SoCal. Once we start to see weak ridging back into 
our region early next week, daily highs will gradually warm, 
attaining near normal values for the time of year (middle 90s for 
the lower deserts) during the middle of the upcoming work week. 

&&

.AVIATION...Updated at 0532Z. 

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation concerns through the TAF period. Activity has
since moved out of the region and the terminals have had some time
to relax. Going forward winds will be light and VRB until ~08-10Z,
where an easterly component will then prevail through the morning
hours. Wind speeds will be aob 10kts. FEW-SCT low to mid level 
clouds will persist through most of the TAF period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns through the TAF period. Winds at KIPL
will be light and VRB, where as at KBLH winds will mostly be light
and VRB with a period of westerly winds tomorrow afternoon. Wind
speeds will be aoa 10kts. Mostly clear skies for the TAF period.

&&

.FIRE WEATHER...
As a low pressure system meanders over Southern California, chances
for wetting rainfall and isolated to scattered thunderstorms 
remain today, mainly focused over the high terrain of the eastern 
districts (20-50% CWR) and fairly widespread across the western 
districts (30-60% CWR). Rain chances will end across the area by 
Sunday evening, with only lingering chances over the AZ high 
terrain Sunday during the day. MinRHs will continue in the 30-45% 
range and temperatures in a 5-8 degrees below normal range 
areawide today and Sunday, with humidity gradually decreasing and 
temperatures gradually warming early next week.

&&

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

$$

SHORT TERM...Lojero
LONG TERM...Whittock 
AVIATION...Ryan 
FIRE WEATHER...Whittock