116
FXUS65 KPSR 170955
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
255 AM MST Mon Mar 17 2025

.SYNOPSIS...
Dry, warm, and breezy conditions are expected for Saint Patrick`s
day today. A dry weather system passing through tonight through
Tuesday will lead to continues widespread breeziness, with the
strongest winds in Southeast California tonight. Temperatures will
also cool down several degrees below normal Tuesday before
warming back up to more seasonal levels, to slightly above normal,
with lower desert highs in the lower to middle eighties. Strong
high pressure next week will push high temperatures into the
nineties.

&&

.DISCUSSION...
A low-amplitude longwave ridge remains in place over the Southwest
early this morning, with a stream of high clouds continuing to
filter in from the west. Despite the persistent high clouds today,
high temperatures are forecast to reach around the 80 degree mark
for the lower deserts. The high clouds will help alleviate the
sun`s intensity, but the afternoon temperatures will still lead to
Minor HeatRisk levels. Which means people extremely sensitive to
the heat should take precautions to protect themselves from the
heat.

Over the next 24-36 hours, a trough, currently upstream off the
NorCal coast, will drop southeast through the Desert Southwest. It
still looks like there will be no luck for any precipitation from
this trough for Southern AZ and Southeast CA, with all hi-res
models keeping most precipitation on the windward side of the
SoCal Mtns and mostly north of I-40 in AZ. But hey, there is
at least potential for a rainbow in a ring around the sun for St.
Patrick`s day.

The biggest impact from this trough will be widespread breezy
to windy conditions, as unseasonably strong 850-500mb winds - up
around the 98th-100th percentile for this time of year - pass
overhead as the trough moves through. Fortunately, the timing of
the passage of the trough axis, and an associated surface front,
will occur this evening through tonight, which should limit
surface wind magnitudes to a degree. If passage happened more
during the daylight hours then this would likely be a much more
impactful wind system. Nevertheless, widespread wind gusts up to
and in excess of 25-30 mph are expected beginning out west in
Southeast CA this afternoon and expanding eastward through
southern AZ tonight. The gusty winds will reach the Phoenix area
with the cold front as early as 10-11 PM tonight. Strongest winds
will occur across Southeast CA and parts of Southwest AZ this
evening and tonight where the pressure gradient will be strongest
and downsloping influences will help accelerate winds. Latest
HREF probabilities for advisory level winds (gusts >40 mph) are
very high (80-100%) for a large portion of Southeast CA. There is
still some uncertainty in how much momentum transfer to the
surface will occur during the overnight hours and likely there
will be some sheltered areas, but have elected to expand the Wind
Advisory for all of Southeast CA, and the Yuma, AZ area, beginning
at 5 PM MST/PDT today. Some of the higher peaks in S. Gila County
may also reach advisory level Tuesday afternoon, but will hold
off on a Wind Advisory at this time. Advisory level winds out west
are expected to come to an end before noon Tuesday, but gusty
conditions will continue through sundown Tuesday evening. As with
any strong wind system, blowing dust is likely, with potential for
some localized visibility reductions out west.

Temperatures will cool down again Tuesday, back below normal, as
the trough and cold front pass through. High temperatures Tuesday
will range from 65-75 degrees across the lower deserts, which is
around 6-8 degrees below normal. Following the Tuesday trough,
temperatures will gradually warm back up, with still slightly
below normal temperatures Wednesday before returning to slightly
above normal by Thursday, with lower desert highs back in the low
80s. Another couple shortwave troughs passing farther to the
north Thursday and Saturday will keep 500mb heights from a more
significant rise and thus keep afternoon high temperatures late
this week through Saturday mostly in the low to mid 80s. However,
this suppression of heights aloft will only last so long and
global models still show strong agreement in the development of a
strong, high amplitude, ridge across the West by the beginning of
next week. There is already high confidence that this ridge will
lead to 90 degree temperatures for the lower deserts beginning as
early as Monday next week. Global models further show the ridge
axis shifting more overhead during next week, which will likely
push lower desert highs into the middle-90s toward the middle of
the week and potentially near daily records. So, enjoy the more
seasonal temperatures this week before things really heat up next
week!

&&

.AVIATION...Updated at 0510Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Easterly winds will persist through Monday morning before shifting
out of the west by the early afternoon hours and remaining out of
the west through the rest of the period. Wind speeds through
Monday morning will generally be light aob 7 kts, with speeds
increasing somewhat into the afternoon hours as occasional gusts
approach into the mid to upper teens. Winds subside below 10 kts
temporarily Monday evening before increasing once again during
the overnight hours as a cold front moves through. SCT to BKN
cloud decks aoa 20 kft will be common throughout the period.

Southeast California/Southwest Arizona including KIPL and KBLH:

Light winds aob 7 kts will be common through Monday morning with
extended periods of directional variability likely. Thereafter,
wind speeds are expected to pick substantially heading into Monday
afternoon out of the west to southwest with gusts potentially
approaching/exceeding 25 kts at times. At KIPL, there can be some
occasional gusts approaching 30-35 kts during the evening hours.
SCT to BKN cloud decks aoa 20 kft will be common throughout the
period.

&&

.FIRE WEATHER...
A period of elevated fire weather conditions is anticipated this
afternoon and again midday to early afternoon tomorrow, for parts
of Southeast CA and along the Lower Colorado River Valley, as a
dry weather system swings through the region. Strong west to
northwest winds are expected beginning this afternoon, with gusts
reaching to and above 30 mph beginning as early as 4-5 PM PDT. In
the late afternoon and early evening, RH values will still be
around 15-20% before increasing above 25% areawide by 7 PM. Strong
winds will continue through tonight and then there will be a
period around midday to early afternoon tomorrow when NW wind
gusts will still be around 25-30 mph while RH values dip to
10-15%. Wind gusts up to 30-40 mph are also anticipated in parts
of Southern Gila County Tuesday afternoon, but MinRH values are
expected to remain above critical level (15%). Beyond Tuesday,
conditions will remain very dry, with daily MinRH values around
10-15%, and winds will remain fairly light, while following
typical diurnal trends each day, aside from a slight uptick
Thursday. Fairly seasonal temperatures are expected this week,
with no rain chances, and then temperatures really shoot up into
the 90s next week as strong high pressure develops.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory from 5 PM this afternoon to 5 AM MST Tuesday for
     AZZ532.

CA...Wind Advisory from 5 PM this afternoon to 5 AM PDT Tuesday for
     CAZ563-565>567.

     Wind Advisory from 5 PM this afternoon to 9 AM PDT Tuesday for
     CAZ560-561-564-568>570.

     Wind Advisory from 2 PM this afternoon to 9 AM PDT Tuesday for
     CAZ562.

&&

$$

DISCUSSION...Benedict
AVIATION...Lojero
FIRE WEATHER...Benedict