288
FXUS65 KPSR 042018
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
118 PM MST Wed Nov 4 2026

.KEY MESSAGES...

- Major waterways such as the Salt and Gila Rivers will continue
  to experience high volumes flows through at least the end of the
  week due to dam releases.

- With the exception of a slight chances of mountain showers to
  finish out the workweek, dry weather will be common through at
  least the next seven days.

- Temperatures a few degrees below normal will warm very close to
  seasonal readings by this weekend.

&&

.SHORT TERM /Today through Friday/...
Afternoon objective analysis reveals a rather dynamic pattern over
the CONUS with closed lows spinning near the Utah-Colorado border
and upper Midwest. These disturbances are now in close enough
proximity to where they have severed an omega block type setup that
brought short-lived ridging to the Desert Southwest yesterday.
However, the western most system will only flatten out heights
aloft across Arizona and southern California, which will promote
tranquil conditions through Thursday. The pattern will take on a
bit more cyclonic curvature by Friday as a decaying shortwave
dives south from the Pacific Northwest. Guidance points towards a
slight dip in the height fields as a result of the associated
ascent aloft, but, as mentioned in the previous discussion,
confidence remains low on exactly where this potential trough will
setup. Regardless of positioning, intensity will likely be
lacking, which would result in only some minimal to minor impacts
areawide. The most expected from this system as of now is breezy
conditions for portions of the region Friday into Saturday and
perhaps some terrain driven shower activity Friday afternoon.

Day-to-day temperatures the next few afternoons will run relatively
steady thanks to the above-mentioned zonal flow. Lower desert
highs will range generally in the mid to upper 70s with perhaps a
few spots reaching into the lower 80s, around 3-5 degrees below
normal for the start of November. Even with the above-mentioned
disturbance, highs on Friday will actually trend upwards due to
efficient lower troposhperic heating, hovering within a degree or
two of seasonal levels by that point.


&&

.LONG TERM /Saturday through Tuesday/...
During the weekend, some semblance of a Rex block (or omega block)
will develop in the southern stream with weak troughing over
northern Mexico and broad ridging across the Great Basin/central
Rockies. While the precise orientation and positioning of salient
features remain uncertain based on notable ensemble differences, the
overall pattern will promote surface pressure rises over the
intermountain West and dry N/NE boundary layer flow. Based on the
pattern, periods of breezy northeast winds are likely at times over
the weekend and early next week, though nothing particularly strong
or unusual for this time of year. At some point early next week, the
bulk of ensemble members eject the northern Mexico wave through the
forecast area bringing enhanced mid/upper level moisture. It remains
to be seen whether this process can overcome the dry boundary layer
airmass, with the highest odds suggesting dry weather persisting.
With H5 heights remaining nearly steady state in a 580-584dm range,
temperatures should follow a near persistence trends with readings
not terribly far from climatology.

&&

.AVIATION...Updated at 1740Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns are expected through the forecast
period under mostly clear skies. Winds will remain light
(generally 7 kts or less) and follow typical diurnal patterns at
the Phoenix Metro terminals. Wind directions at KBLH and KIPL
will generally remain N-NW through tonight. Extended periods of
calm and vrb conditions can also be expected at all terminals,
especially during any diurnal wind shifts.

&&

.FIRE WEATHER...
While a stray shower may affect mountains of eastern districts
Friday, the area will remain dry with little to no chance of wetting
rainfall through early next week. Minimum afternoon humidity levels
will largely fall into a 20-30% range in western districts and 30-
50% in eastern districts. This will follow fair to good overnight
recovery in western districts and good to excellent levels in eastern
districts. Winds speeds will remain seasonably light for the majority
of the period, albeit obtaining 20-30 mph northerly gusts through
the lower Colorado River valley late in the week. Increased easterly
winds will also be likely in eastern districts early next week.

&&

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

$$

SHORT TERM...RW
LONG TERM...18
AVIATION...Salerno
FIRE WEATHER...18