665
FXUS65 KPSR 171705
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1005 AM MST Fri May 17 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
High pressure will strengthen over the region the next couple days
resulting in many more lower desert communities exceeding 100
degrees. A dry weather disturbance will move north of the region
early next week with temperatures retreating closer to the seasonal
normal. Occasionally breezier conditions are likely during the
afternoon and evenings early next week under mostly clear skies.

&&

.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...Updated at 1705Z.

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

No major weather issues will exist through Saturday afternoon with
only a FEW distant cloud decks over mountains. Wind behavior across
the Phoenix metro will be similar to the past 24 hours, albeit with
afternoon/evening winds somewhat less gusty (only sporadically
around 15-20kt). At the SE California terminals, confidence is good
that a light S/SE component will transition to W/SW by this evening
with gusts ~25kt common after the wind shift.

&&

.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...18
FIRE WEATHER...Kuhlman