419
FXUS65 KPSR 021100
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
400 AM MST Fri Jan 2 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- Dry weather will return to the region through the weekend with
temperatures hovering a few degrees above normal.

- A period of unsettled weather may return during the middle of next
week with chances of light rain returning.

&&

.SHORT TERM /Today through Saturday/...
Shortwave energy over central Utah early this morning was cresting a
prevailing SW Conus ridge, and will quickly propagate into the
plains over the next 24 hours. This will leave the forecast area
under growing large scale subsidence with high pressure re-building
into the region. While this transition represents a general drying
trend, thick boundary layer moisture remains trapped over much of
the CWA this morning in the form of low clouds and patchy fog.
Forecast soundings and satellite trends suggest more prevalent low
clouds vs dense fog, though cannot discount periods of fog in the
most favorable spots this morning (and to a lesser extent Saturday
morning). Otherwise, scattered clouds will persist through the
afternoon with excellent confidence of temperatures reaching 3F to 6F
above normal. Low level moisture will partially scour Saturday as H5
heights increase modestly allowing temperature to warm a couple
degrees above persistence.

&&

.LONG TERM /Sunday through Thursday/...
The hemispheric longwave pattern will only be slow to advance
through the middle of next week owing to stubborn downstream North
Atlantic blocking. Ensemble membership remains in excellent
agreement indicating low amplitude ridging prevail across the SW and
central Conus while East Pacific troughing only slowly edges towards
the West Coast. A series of lead shortwaves will almost certainly
eject from the longwave trough position early in the week, however
only de-amplify and lift into the Great Basin bringing a cold front
onshore into cntrl/srn California, but no further. A more defined
cold core should drop towards a developing weakness in the midlevel
height field into the Southwest during the middle of the week. While
a handful of ensemble members still depict an earlier arrival
(particularly in the CMC suite), the trend among the preponderance
of membership suggests a slower PV passage sometime in the Wednesday
time frame.

While low level moisture will not completely be eliminated early in
the week, warmer air aloft and rain shadow effects from prevailing
W/SW flow will limit any inland deep saturation and rain chances. As
usual, NBM POP bias in SE California becomes evident bleeding higher
chances off mountains to the west, and have trimmed values back
appropriately. It would not be uncommon for thicker cirrus decks to
impact daily highs at some point early in the week, however
numerical guidance remains consistent in advertising readings a few
degrees above the daily normals into the middle of the week.
Uncertainty in the precise track and intensity of the PV anomaly
moving into the region midweek limits a larger POP mention in the
official forecast with the majority of model output leaning towards
another weakening wave and limited ascent/precipitation potential.

&&

.AVIATION...Updated at 1100Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Forecast confidence is only low to moderate this morning due to a
combination of low clouds and fog around the region. Cigs 6K-8K AGL
should be the most common feature this morning, however patches of
cigs near 3K ft have been reported, as well as pockets of shallow
fog outside the metro. Probabilities of direct weather impacts and
flight restrictions to any specific aerodrome are too low to include
at this time. Otherwise, scattered decks 040-060 are possible
through mid/late afternoon before dissipating with sunset. Light
east winds should attempt a westerly switch this afternoon, however
may remain variable for extended periods.


Southeast California/Southwest Arizona including KIPL and KBLH:
Patchy fog with reduced visibilities may become an issue this
morning, however coverage and magnitude of any potential direct
impact remains uncertain. Have maintained a VCFG mention with this
TAF package with lower probabilities of worsening flight categories
through 17Z (IFR or lower). Forecast confidence is better beyond
this morning with clearing skies and light N/NW winds through
Saturday morning.

&&

.FIRE WEATHER...
Moisture levels will remain seasonally elevated through much of next
week with minimum afternoon readings only falling into a 40-60%
range.  This will follow excellent overnight recovery greater than
75%. Very light winds with several periods of nearly calm readings
may increase somewhat during the middle of next week. A dry weather
pattern through the first part of next week may become more
unsettled during the middle of the week with increased chances for
wetting rain.

&&

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

&&

$$

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

NWS Phoenix (PSR) Office