874
FXUS65 KPSR 191139
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
439 AM MST Sun May 19 2024

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
A weather disturbance will slide primarily north of the region
early this week, but it will allow temperatures to retreat closer
to the seasonal normal. This system will also bring an increase in
winds, especially during the afternoon and evening hours with
Monday having the strongest winds and greatest impacts. Very
tranquil weather with near normal temperatures will prevail during
the second half of the week.

&&

.DISCUSSION...
A Pacific upper level trough is gradually shifting southward
across Pacific Northwest into the Great Basin with a much weaker
southern branch shortwave trough now tracking through the Desert
Southwest. The disturbance moving across our region will help to
lower temperatures today several degrees from yesterday`s highs
in the lower 100s, while winds will become breezier over much of
the area. The main forecast concern over the next couple days will
be the increased winds combining with low humidities to create
elevated to near critical fire weather conditions. Wind gusts this
afternoon and early evening are expected to easily reach into the
mid 20s areawide to 30-35 mph across portions of southeast
California. As the trough to our north continues to shift farther
south, the gradient over our region will increase into Monday
while another shortwave trough currently well west of southern
California tracks through our region. Both of these features will
enhance winds further with wind gusts Monday afternoon and early
evening likely reaching 25-35 mph across south-central Arizona to
30-45 mph across the western deserts of southeast California
through the the Lower CO River Valley. Near critical fire weather
conditions are expected over much of the area Monday afternoon.

Temperatures will continue to trend downward on Monday with
afternoon highs mostly in the lower 90s, or a couple degrees
below normal. The broad troughing over the Western U.S.,including
our region, should then persist through the rest of the week as
several progressive shortwaves are forecast to track across the
Northwestern U.S before sliding just to the north of our region.
This should keep upper level heights fairly stable over our region
at between 574-578dm, or right around climatological normal for
this time of year. This will keep seasonably dry conditions in
place through the coming week with temperatures right around
normal. Guidance is still suggesting we will eventually see a
warming trend, but as of now that should hold off until around
Memorial Day.

&&

.AVIATION...Updated at 1139Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Persistence of typical diurnal wind tendencies is expected through
the TAF period at all terminals. East winds this morning should
veer W-SW by 19-20Z, with a brief period of southerly winds during
the shift. Afternoon wind speeds will increase to as high as 10-15
kts with gusts as high as 20-25 kts. Winds will subside this
evening and shift back east between 7-11Z. SKC will prevail
through tonight, followed by SCT-BKN clouds developing aoa 15K ft
Monday morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
Light and variable winds at KBLH this morning will increase from
the south-southwest by midday with afternoon speeds increasing
into the middle teens with gusts up to 20-25 kts. At KIPL, west
winds will prevail through the TAF period. Winds will be lightest
this morning and increase up to 15-20 kts this afternoon and
evening with gusts up to 25-30 kts. SKC will prevail through this
evening followed by FEW-SCT high clouds developing Monday morning.

&&

.FIRE WEATHER...
A disturbance moving mostly north of the districts early this
week will force temperatures to cool closer to the seasonal normal
while also producing a period of strong, gusty winds. Throughout
the week, minimum afternoon humidity levels will fall into the
single digits at lower elevations and the teens across higher
terrain areas. This will follow poor to fair overnight recovery of
20-40%. Widespread wind gusts as high as 30-35 mph may be common
Monday afternoon yielding an extended period of near critical
thresholds when combined with low RH and dry fine fuels. Land
managers should be cautious for rapid, uncontrolled spread of any
ongoing fires or new starts Monday. Otherwise, afternoon gusts of
20-25 mph should be more representative the remainder of the week
resulting in a slightly elevated fire danger.

&&

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

$$

DISCUSSION...Kuhlman
AVIATION...Benedict
FIRE WEATHER...Kuhlman