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000
FXUS65 KPSR 140817
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
115 AM MST Sun Apr 14 2024

.SYNOPSIS...
A weather disturbance moving through northern Arizona and southern
Utah will result in locally windy conditions and temperatures
retreating closer to the seasonal normal the next couple days.
However, strong high pressure building into the region later this
week will allow temperatures to warm rapidly with some lower desert
communities possibly approaching close to the 100 degree mark late
in the week.

&&

.DISCUSSION...
A well defined negative PV anomaly continues to propagate southeast
along the central California coast, however satellite imagery
depicts the first signs that subtropical jet energy was influencing
the circulation towards an eastward turn. As a result, the central
cold core and more pronounced height falls will translate inland
towards southern UT over the next 36 hours. Nevertheless, increased
pressure packing along a decaying cold front crossing the coast
range will support enhanced winds descending into lower elevations
of Imperial County again this afternoon and evening. While not the
optimal scenario for strong mountain rotors, deep mechanical
transport of higher momentum air will support a brief period of
advisory level winds. By Monday, the greatest combination of jet
energy, midlevel height falls, and tightened pressure gradient will
have shifted into New Mexico though a few stronger ridge top gusts
across Gila County may be common.

Operational and ensemble members continue to consolidate on a
singular solution later this week featuring mean troughing shifting
into the Upper Midwest/Great Lakes and dampened ridging building
over the SW Conus. Trends among NAEFS membership show less support
for higher amplitude riding, but rather H5 heights becoming
sequestered around 582dm due to low amplitude perturbations being
pulled eastward in an active subtropical jet. As a result, NBM
probabilities of lower elevation communities reaching 100F this week
have dropped considerably below 25%. Regardless, forecast confidence
is excellent that temperatures will hover 5F-10F above normal during
the latter half of the week with numerical guidance spreads
narrowing significantly. This pattern of quasi-zonal, dry westerly
flow should persist into the weekend yielding an extended period of
widespread minor HeatRisk, but nothing terribly unusual for mid/late
April.

&&

.AVIATION...Updated at 0520Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Easterly winds will establish over the next few hours at KPHX. A
similar evolution in the wind directions can be expected tomorrow to
that of what we saw over the last few days; winds veer SE-SSE over
the late morning hours, followed by a southerly cross runway
component with sustained speeds aob 10 kts and occasional gusts into
the mid teens midday, and SW winds establishing in the mid-late
afternoon. Gusts are anticipated to peak in the upper teens to low
20s. Tomorrow evening, a dry cold front will pass over the Phoenix
area, which could lead to westerly gusts persisting later into the
evening, and confidence is moderate that winds will remain west
through tomorrow night. Mostly clear skies will prevail through the
period.


Southeast California/Southwest Arizona including KIPL and KBLH:
The primary aviation weather concern through the TAF period will be
gusty winds out of the W at IPL and SW at BLH, under mostly clear
skies. Elevated winds are expected to persist through the TAF period
at IPL (except for perhaps a few hours before sunrise tomorrow), and
winds will calm between 07-09Z at BLH before picking back up shortly
after sunrise tomorrow morning. Although LLWS criteria are unlikely
to be met, times where the surface decouples sufficiently overnight
could lead to 10-20 kts of shear between the surface and 2 kft AGL.
Gusts are expected to peak between 30-35 kt and occasionally up to
40 kts late afternoon into the early evening at IPL, whereas gusts
will peak between 25-30 kt at BLH. During the strongest gusts,
reduced visibilities from blowing dust will be possible,
particularly at IPL.

&&

.FIRE WEATHER...
With dry weather prevailing, near normal temperatures early this
week will rapidly warm back into an above normal category during the
latter half of the week. Very breezy afternoon conditions will be
common through Monday, especially across western districts today and
eastern district ridge tops Monday. As minimum afternoon humidity
levels fall into a 10-25% range, a locally elevated fire danger will
exist. With warmer temperatures later in the week, minimum humidity
levels will dry further into a 10-20% range with single digits
common across lower desert locations. Overnight recovery will turn
poor to fair in a 20-40% range. However, lighter wind speeds will
preclude a greater fire danger and provide an excellent opportunity
for prescribed burning during the middle of the week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 6 AM PDT Monday for CAZ562.

     Wind Advisory from 3 PM this afternoon to 11 PM PDT this
     evening for CAZ563-566-567.

&&

$$

DISCUSSION...18
AVIATION...Whittock
FIRE WEATHER...18