990
FXUS65 KPSR 191102
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
402 AM MST Sun Jan 19 2025

.UPDATE...Updated 12z Aviation Discussion.

&&

.SYNOPSIS...
Dry but breezy to windy conditions will develop across the region
early in the work week. Temperatures will continue to run below
normal levels, with the coldest temperatures likely Tuesday night.
Warming conditions back to above normal level are anticipated for
late this upcoming week.

&&

.DISCUSSION...
Mostly clear skies persist across the region, with only some high
clouds brushing the northern fringes of south-central Arizona as
the well-advertised cold, Arctic airmass continues to deepen
across central CONUS. Here locally, dry northerly to northwesterly
flow will be the predominant flow pattern through early this week
as deep longwave troughing persists across most of CONUS.

This flow pattern will ensure dry conditions, with drier air
filtering in from the north behind a shortwave moving through the
Great Basin and Desert Southwest on Monday. This feature will aid
in cooler than normal conditions to continue, with overnight
temperatures cooling by several degrees by Tuesday night, where
widespread areas of the lower deserts could observe lows dipping
below freezing. Additionally, strong winds from the north will
develop, especially along the Lower Colorado River Valley on
Monday, as a strong north to south oriented jet develops in
combination with the troughing feature and building high pressure
over northern California. Wind Advisories are now in effect for
the Lower Colorado River Valley in addition to the forecast zones
along the I-10 corridor westward in Riverside and Imperial
Counties, where winds are expected to gust 40-50 mph Monday into
Monday night. The main concerns with these strong wind gusts will
be the crosswinds that could impact high profile vehicles,
especially along I-10 from Blythe to Indio, as well as blowing
dust reducing visibilities in dust- prone channels.

A much quieter weather pattern is anticipated to settle into
western CONUS as positive height anomalies creep in from the west
as the longwave Arctic trough slowly migrates northeastward
going into the latter portions of the week. Another reinforcing
trough diving southward into the Front Range is unlikely to slow
a warming trend that is set to commence with these building mid-
level heights by Wednesday. Thus, dry conditions will continue
through the end of the week, with this noteworthy dry stretch
getting near record territory for central Phoenix (currently 149
consecutive days of no measurable precipitation, with the longest
dry streak of 160 days).

Ensembles remain in excellent agreement of ridging overhead
through at least Thursday, with more divergence in regards to the
pattern evolution heading into the weekend. All ensemble means
depict yet another Arctic trough digging southward from Alaska
late this week, with some version of continued deepening into
western to central CONUS heading into this upcoming weekend. The
current discrepancies lie in how quickly this trough will amplify
and how strong this trough will become, at least as early as
Saturday. This development has the potential to result in more
active weather conditions for the region, but given the large
spread in possibilities, hard to determine any reasonable
scenarios at this point beyond some level of a cooling trend for
this period.

&&

.AVIATION...Updated at 1102Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns will exist through the TAF period
under mostly clear skies. Winds will continue to follow typical
diurnal trends, with speeds mostly AOB 6 kts. Periods of
variability to nearly calm conditions will be common. Expect some
passing mid and high level cloud decks (AOA 20 kft AGL) to skim
the north of the airspace this morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected over the next 24 hours under
clear skies. Both terminals are expected to maintain VRB
conditions through the TAF period with N`rly winds returning by
Monday morning.

&&

.FIRE WEATHER...
Temperatures should hover close to the seasonal normal through the
middle of next week with expansive dry air in place resulting in
essentially no chance of wetting rainfall. Minimum afternoon
humidity levels will settle in a 15-25% range today, then closer
to a 5-15% range next week with a renewed surge of drier air.
Weekend fair to good overnight recovery of 30-60% will deteriorate
towards poor recovery of only 15-30% next week. While some gusty
north winds resulting in a period of elevated fire danger will
exist mainly on Monday and Monday night for the western districts
and some higher terrain areas of the eastern districts, light
winds will become more common over the remainder of the region.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory from 11 AM to 11 PM MST Monday for AZZ530.

CA...Wind Advisory from 10 AM to 10 PM PST Monday for CAZ564-568>570.

&&

$$

DISCUSSION...Young
AVIATION...Whittock/Ryan
FIRE WEATHER...Young