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352
FXUS65 KPSR 171146
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
446 AM MST Fri May 17 2024

.UPDATE...
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Updated Aviation Discussion.
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&&

.SYNOPSIS...
High pressure will increase over the region into the weekend
leading to even warmer temperatures with most lower desert
locations seeing highs top out at or just over 100 degrees today
and Saturday. A dry weather disturbance is then expected to move
through the region during the first part of next week eventually
leading to temperatures closer to normal through the middle of
next week. Clear to mostly clear skies are expected each day,
while breezier conditions are likely Sunday through early next
week.

&&

.DISCUSSION...
The compact vort max that brought yesterday`s convection to
portions of south-central Arizona has now moved into northern
Mexico with upper level ridging quickly filling in from the west.
As H5 heights rise to between 582-584dm by tonight and drier air
slowly works through the region, modest warming will be realized
with daytime highs peaking today across the western deserts
between 100-103 degrees to the upper 90s to around 100 degrees in
the Phoenix area. The ridge axis will then quickly move to the
Arizona/New Mexico border Saturday morning as a weak shortwave
trough approaches southern California. Temperatures Saturday
should already start to cool off a couple degrees over the western
deserts, but warm another couple degrees across the south-central
Arizona lower deserts with highs peaking in the lower 100s in
Phoenix. Both days should present a Moderate HeatRisk for a good
portion of the lower deserts.

A very weak shortwave trough is forecast to quickly move through
the region Saturday night/Sunday morning lowering heights aloft
enough to drop daytime highs Sunday into the upper 90s. Winds
should also pick up by Sunday with an increasing gradient with
afternoon/evening gusts upwards of 25-30 mph in some places.
Further cooling and continued breezy conditions are then expected
during the first part of next week as a larger Pacific trough
drops south southeastward through the Great Basin into the Desert
Southwest Monday into Tuesday. This should drop H5 heights down
to between 572-578dm and lower 850mb temperatures 2-3C across the
region. By Monday, NBM forecast highs drop to around 95 degrees
with some lower desert areas as low as the lower 90s, or right
within the normal range for this time of year. Aside from higher
clouds on Monday, the trough will be dry with no realistic rain
chances, even over the Arizona high country. The weather pattern
going into the latter half of next week should keep broad upper
level troughing in place, but a slight retrograding of the trough
by next Friday or Saturday may result in some ridging building
back into the Desert Southwest from the southeast. If this holds
true, temperatures will likely start to creep back closer the
upper 90s by next weekend.

&&

.AVIATION...
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Updated at 1145Z.

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

Typical diurnal wind trends are expected through the next 24
hours, with speeds generally 10 kts or less. Light variability is
anticipated during diurnal transitions and the afternoon will
feature gusts to around 15-20 kts. SKC will prevail. Although
there may be a few small cumulus in the afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:

West winds this morning at KIPL will become variable and/or shift
E-SE during mid to late morning. West winds will then return by
22-23Z with sustained speeds rising into the middle teens and
gusts as high as 25-30 kts. At KBLH, SW-S winds will prevail with
elevated speeds sustained in the middle teens and gusts into the
middle 20s this afternoon. Winds subside at both terminals by
midnight. SKC will prevail.
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&&

.FIRE WEATHER...
High pressure will settle over the region today into the weekend
with warmer temperatures and drying conditions. This will lead to
daily highs around 100 degrees across the lower deserts and MinRHs
falling to around 10% through Saturday. Breezy conditions with
afternoon gusts up to around 20 mph over the eastern districts to
25 mph across the western districts can expected through Saturday
before increasing further for Sunday and Monday. The combination
of low RHs and breezy afternoon winds will likely result in
elevated fire danger through at least the weekend where there are
abundant dry fine fuels. A dry weather system is then expected to
move through early next week resulting in temperatures closer to
normals, but continued breezy conditions and MinRHs around 10%.

&&

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

$$

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