641
FXUS65 KPSR 092005
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
105 PM MST Sat Nov 9 2024

.SYNOPSIS...
Quiet weather with dry conditions will continue through next week.
Temperatures will warm towards near normal levels early in the week
with additional warming into an above normal range by the latter
half of the week. A changing weather pattern next weekend may result
in more unsettled conditions across the region.

&&

.DISCUSSION...
Dampened ridging was building into the SW Conus early this afternoon
as an occluded cyclone was slowly ejecting through the central
plains while strong jet energy and a pinched trough approached the
west coast. Objective analysis indicates H5 heights have already
rebounded near 576dm across the forecast area with additional modest
height rises likely over the next 24-36 hours. As a result,
confidence is very good that temperatures will return into a near
normal range the next couple days. Progressive/zonal flow will
continue through next week as ensembles have consolidated on a
solution of a full latitudinal trough progressing through western
CONUS, albeit with the primary vorticity center and forced ascent
passing north of the CWA Tuesday. Given the displaced nature to this
system, only a brief, modest cooling should be expected with
readings still hovering not far from climatology.

Otherwise, more pronounced broad ridging and continuation of dry
conditions will be the main weather story the latter half of the
week as H5 heights near or exceed 585dm. While ensemble guidance
spread is still rather wide given uncertainty in the ultimate
magnitude of the high pressure bubble, all indications suggest
further warming and temperatures reaching 4F-8F above normal.
However, this warm spell should be rather short lived as a more
energetic/amplified trough digs towards the SW Conus over the
weekend. The NAEFS ensemble suite during this time frame generally
falls into 3 camps: 1) a narrow, positively tilted trough only
skirting the region with minimal overall impacts, 2) a primarily
overland trajectory to a deepening negative PV anomaly filling into
a trough base over Arizona creating very good ascent mechanisms, but
accessing limited moisture flux, and 3) a westward shifted, quite
intense PV anomaly able to incorporate and entrain Pacific moisture
resulting in a wet, unsettled period just beyond this forecast
period. At this time, a preponderance of solutions would support
outcome #2, however enough evidence exists and only subtle
differences separate this from outcome #3. Not surprisingly, model
spread is quite large towards the end of the forecast period,
however almost all modeling supports at least a period of slightly
below normal temperatures beginning next weekend.

&&

.AVIATION...Updated at 1700Z.

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

No aviation weather concerns under some passing high cirrus decks
can be expected through the next 24 hours. The overall wind pattern
will continue to feature diurnal tendencies with light speeds aob 5
kts along with extended periods of light variability to calm
conditions.

&&

.FIRE WEATHER...
Temperatures will gradually warm closer to near normal levels
through early next week with even warmer conditions late in the
week. Winds will follow a typical diurnal upslope/nocturnal drainage
component with only some modest morning ridge top gustiness during
the middle of the week. MinRHs will fall mostly in a 10-15% range
through next week with readings closer to 20-25% over higher terrain
of eastern districts. Overnight recovery will be better in the
eastern districts, mostly between 40-60% with poor to fair overnight
recovery (around 20-40%) in lower elevations and  western districts.
Overall, dry weather will persist through late next week with
conditions remaining favorable for any prescribed burning operations.

&&

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

&&

$$

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