000
FXUS65 KPSR 261159
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
459 AM MST Tue Mar 26 2019

.SYNOPSIS...
The warming trend will continue through midweek as high pressure
builds across the Desert Southwest. Daytime temperatures will peak
Tuesday with highs near the 90 degree mark across the lower
deserts. Cooler and breezy conditions are expected late in the
week as a low pressure system passes by to the north.

&&

.DISCUSSION...
High clouds are streaming over the desert southwest this morning
in response to an upper level low off the Pacific coast. Today
will be the last day for influence from a weak ridge that has been
warming temps for the past few days. Today should be the warmest
day of the week reaching near 90 in Phoenix. If it does hit 90 it
will be the first time for 2019 and only a few days before the
climatic average which is March 28th.

Wednesday will see a shift with a trough approaching the west
coast lowering pressure over the region. This will result in an
increase in high clouds and bring breezy conditions. No
precipitation for our area is expected as the low will pass well
north of Arizona. Numerical models start to diverge by the weekend
hinting at possibility of one or more weather systems that might
impact the region. However, at this time, none appear likely to
bring any rainfall.

&&

.PREVIOUS DISCUSSION...
Clear skies are present across almost the entire Southwest U.S.
this afternoon as shortwave ridging is in place. Temperatures have
warmed into the low 80s across all desert areas with very light
winds. A modest increase in 850-mb temps to near 16 C tomorrow
will support what is likely to be the warmest day of the year so
far. The high temperature for Phoenix and Yuma is forecast to be
90 degrees, which would end a streak of 148 days at Phoenix since
the last 90 degree day. Otherwise, quiet weather should persist
into the later portion of the week amidst a gradual cooling trend.

Westerly flow aloft is forecast to increase to the north of the
Phoenix area later this week amidst a more active large-scale
pattern over the Great Basin and Pacific Northwest. Still some
uncertainty whether a more well-defined shortwave trough can
evolve out of this and progress southward across the Southwest
this weekend, which would have implications on temperatures and
potentially usher in some breezier winds. Given the uncertainty,
just maintained a forecast for slightly above normal temperatures
throughout the weekend and into early next week. Some signs that
another transition back to a more active pattern across the
western U.S. may occur early to middle of next week with the
development of a potentially deep upper trough across the
Southwest.

.AVIATION...Updated at 1200 UTC.

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

There are no aviation weather concerns today. Winds will remain
mostly light to occasionally light and variable favoring typical
diurnal headings. High clouds will pass over the region later
Tuesday AOA 25kft.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Thursday through Monday:
The main weather concern for this period will be breezy
afternoons, especially across Southeast California, western
Arizona and any exposed ridge tops in the Tonto NF. The strongest
wind breezes will occur on Thursday afternoon with gusts as strong
as 25 mph possible at the aforementioned locations. Breezes will
accompany each afternoon through the weekend as well. The drying
trend will continue with minimum relative humidity values dropping
below 15 each afternoon across the lower desert, while remaining
near 20 percent in the mountainous areas. Overnight recoveries
will be in the 30-50 percent range. Otherwise, temperatures peak
near 90 degrees Tuesday before a slight cooldown for the rest of
the week.

&&

.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected for the next 7 days.

&&

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

$$

DISCUSSION...Waters/Rogers
AVIATION...Deems
FIRE WEATHER...Deems

NWS PSR Office Area Forecast Discussion