Strong Wind in Arizona, May 11, 2018

Area Forecast Discussion
National Weather Service Phoenix AZ
221 PM MST Fri May 11 2018

.SYNOPSIS...
An upper-level disturbance approaching the region from the north
will begin a cooling trend today that will continue into Saturday.
Windy and dry conditions will also cause very high fire danger
across all of Arizona and far southeast California today and for
the higher terrain east of Phoenix on Saturday. Near to slightly
below normal temperatures will continue through Monday until weak
high pressure allows warmer than normal temperatures to return for
the middle of next week.

&&

.DISCUSSION...
An upper-low over the Great Basin remains well-defined over the
western Great Basin, with accompanying upper-level cloud cover
spreading across southeast California into central Arizona.
The primary impact on our area continues to be the strengthening
wind speeds, and accompanying threats related to fire weather and
blowing dust. Afternoon observations show wind speeds have been
slow to increase thus far, but now seeing fairly widespread gusts
to around 30 kt across the lower deserts. GOES-16 imagery
indicates some increase in blowing dust, especially across
southwest Maricopa County and northwest/north-central Pinal
County. A Blowing Dust Advisory remains in effect here until 6 PM
MST. Humidities have also fallen to near/below 10 percent across
many locations, and are combining with the strong winds and dry
fuels to produce critical fire weather conditions. Expect gusty
winds to continue into the evening, perhaps even peaking closer to
sunset across south-central Arizona.

Breezy conditions will continue into Saturday, although wind
speeds will be weaker than observed today. Will also see
temperatures continue to cool down back near seasonal normals (low
90s for highs). Little change in the large-scale pattern into next
week means temperatures will remain near or slightly above normal
for at least a few days. The cutoff low over the Great Basin is
forecast to weaken nearly in place and meander erratically through
next week, maintaining broad and weak southwesterly flow aloft
across the Southwest. Models continue to hint at a second weak
upper-level disturbance moving eastward from the Pacific into the
Great Basin, which may bring a slight uptick in wind speeds.
However, moisture will remain quite meager and expecting minimal
chances for precipitation in the foreseeable future. Luckily, the
excessive heat appears to remain at bay for the time being.

&&

.AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL:
Todays main aviation concerns will be gusty winds and blowing dust.
South-southwest winds will be gusting up to 25 to 35 kts and this in
term will lead to areas of patchy blowing dust and reduced slantwise
visibilities. Winds will be slow to weaken after sunset with gusty
conditions persisting late into the evening. Skies will remain
mostly clear with FEW to SCT high clouds aoa 25 kft.

Southeast California/Southwest Arizona including KIPL and KBLH:
Todays main aviation concerns will be gusty winds and blowing dust.
South-southwest winds will be gusting up to 35 to 40 kts with areas
of blowing dust and reduced visibilities, particularly at KIPL.
Winds will be slow to weaken after sunset with gusty conditions
persisting late into the evening. Skies will remain mostly clear
with FEW-SCT high clouds aoa 25 kft.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Monday through Friday:

Temperatures will be slightly above normal early next week amidst
a slight warming trend, with high temperatures approaching the
triple digits by Wednesday. Dry conditions will continue to
support humidity values in the single digits for many locations
each afternoon with poor to fair overnight recoveries. Typical May
afternoon breezes are forecast each day with the usual upslope
gustiness, with perhaps a slight increase in wind speeds into
Friday.

&&

.SPOTTER INFORMATION STATEMENT...
Spotter activation will not be needed.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Red Flag Warning until 8 PM MST this evening for AZZ131>133.

     Red Flag Warning from noon to 8 PM MST Saturday for AZZ133.

     Wind Advisory until 8 PM MST this evening for AZZ552>555-557>561-
     563.

     Blowing Dust Advisory until 6 PM MST this evening for AZZ539-553-
     554-559.

CA...Red Flag Warning until 8 PM PDT this evening for CAZ231-232.

     Wind Advisory until 9 PM PDT this evening for CAZ560-564>567-569-
     570.

     Wind Advisory until 5 AM PDT Saturday for CAZ562.

&&

DISCUSSION...Rogers/Hopper
AVIATION...Hernandez
FIRE WEATHER...Hernandez