Forecast-Discussion

000
FXUS65 KPSR 222225
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
325 PM MST Mon May 22 2017

.SYNOPSIS...
High pressure building in from the west will continue a gradual
warming trend across the region through the middle of the week, with
high temperatures rising well above 100 degrees at many lower desert
locations. Somewhat cooler temperatures are likely to return by the
latter portion of next week as low pressure once again moves into
the western US.

&&

.DISCUSSION...
A trailing and elongated shortwave off the large upper low near
the Great Lakes is moving through northern Arizona and bringing
our eastern CWA some scattered cumulus clouds. The pacific upper
ridge still remains situated off the west coast and will continue
to push eastward, with heights peaking over our region tomorrow
and Wednesday. Highs tomorrow will range from 105 to 110 from
western Arizona westward and from 100 to 106 across south-central
Arizona. On Wednesday, temperatures will be near or just a degree
or two warmer than Tuesday. While these temperatures are above
seasonal normals, atmospheric parameters of heights and temps are
not outside of seasonal NAEFS/ESRL percentile ranges. HeatRisk
levels with these temperatures do rise into the moderate to
borderline high categories and given the recent stretch of cooler
weather over the previous week, this warming could catch folks
off-guard.

Temperatures Thursday through next weekend will return to more
seasonal readings as long-wave troughing returns over the western
CONUS. Lowering heights and slight cool advection will create
gradient driven wind increases, especially across the Peninsular
Ranges between San Diego-El Centro Wednesday and then regionally
on Thursday. Gusty surface winds, west to southwesterly in nature,
will sweep into the area and could generate some patchy blowing
dust at times Wednesday for the Imperial area and then across
southeast CA for Thursday. High temperatures tumble to readings
100 degrees or cooler Thursday and could stay below triple digit
readings through the weekend as longwave troughing holds over the
region, keeping elevated thicknesses and warmth removed from the
area.

&&

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

No aviation concerns through the TAF period. Winds will remain
light and follow normal diurnal headings. Skies will remain mostly
clear with FEW to SCT cumulus aoa 10 kft passing over Phoenix
terminals.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
Thursday through Monday:
Westerly wind speeds will be strongest on Thursday, when gusts up
to 35 mph (locally stronger) are forecast to occur. This will
likely create elevated fire weather conditions, especially across
southeast California and the lower Colorado River Valley where the
combination of relative humidities below 15 percent and gusty
winds will coincide. Winds will weaken into Friday, but still
remain slightly breezy. Over the weekend, wind speeds will be
light area-wide as high pressure builds over the Great Basin.

A minor cooldown will occur through Saturday, with highs in the
low to mid 90s forecast each day across the lower deserts. A
warming trend will then commence on Sunday, with high
temperatures in the lower 100s making a return by Monday.

&&

.SPOTTER INFORMATION STATEMENT...
Spotter reports should not be needed.

&&

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

$$

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

NWS PSR Office Area Forecast Discussion