558 
FXUS65 KPSR 311036
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
336 AM MST SUN JUL 31 2016


.SYNOPSIS...
A humid airmass will remain in place over the Desert Southwest
through at least the middle of this week. This will maintain an
active phase of the Monsoon over the Desert Southwest. As always,
there will be large day to day fluctuations in storm coverage and
associated hazards. A downtrend in moisture and storm chances is
anticipated to begin during the latter part of the week. 

&&

.DISCUSSION...
Today...
Thunderstorms over northern Gila County have largely dissipated early
this morning but not before producing runoff in Tonto Creek. USGS
gauge upstream of Punkin Center showed a rise of about 1.5 feet but
has since started to come down. Elsewhere, isolated convective
showers have affected northeastern portions of metro Phoenix. Most
active area of convection is over northern Sonora. Steering flow
should keep debris clouds largely out of our forecast area. Speaking
of flow patterns, it continues to be complex over the region. There
is broad anticyclonic flow from off the southern CA coast through New
Mexico. But, it isn't monolithic as there are multiple anticyclonic
centers within it. There are also some cyclonic features of note with
a short wave over Utah and northern Arizona plus there appear to be some
smaller embedded cyclonic features including one near Rocky Point MX
and another near the Mogollon Rim. Meanwhile, further east, there is
a large upper low/inverted trough centered over south Texas.

Northern Arizona could be active today due to the mid level short
wave and upper level diffluence. Over our forecast area, RAP/GFS/NAM
depict significant CIN remaining (though not overwhelming). Those
models also generally indicate southern AZ will be active again (not
stabilized from Saturday's activity). Hi-res models by and large
keep storms out of our area for later today except for our higher
terrain zone east of Phoenix. This is supported by SPC-SSEO (though
it does indicate potential for significant outflow). However, the
NCAR hi-res ensemble is more enthusiastic for Maricopa/La Paz/Pinal
this evening. Given the moisture availability, Given moisture
availability, surface heating, and outflows, there is at least a
slight chance for our lower elevations later today and tonight.
Temperatures will be a bit warmer today - more noticeably over
portions of SW AZ and SE CA where there had be a lot of debris clouds
on Saturday. 

Monday through Wednesday...
Models generally indicate less unfavorable CIN for Monday (compared
to Sunday) and thus PoPs are slightly higher. For Tuesday and
Wednesday, a low pressure system moving through the Pacific Northwest
leads to high pressure becoming centered over the central Rockies.
Models depict an inverted extending further north into AZ (possibly
combining with a mid level wave out of west TX) and becoming
something of an upper low by Wednesday. PoPs go up a little bit more
because of this but not dramatically as there may be more cloudiness
around which can inhibit instability. Temps will be a bit warmer on
Monday before trending down Tue and Wed (mainly south-central AZ). 

Thursday through Saturday...
The Westerlies make their presence felt during the latter part of the
week. GFS continues to show more of a drying trend than the ECMWF and
is faster at ejecting the low/inverted trough. NAEFS PoPs support
this as well. A key difference appears to be that the ECMWF has more
of an amplified flow pattern with a deeper but sharper trough along
the west coast. This leads to a more of a southerly component to the
flow over our area and thus less drying from the west. Leaned toward
GFS/NAEFS solution as it better reflects climatology. 

&&

.AVIATION... 
South-Central Arizona Including KPHX, KIWA, and KSDL:

Low-level flow will likely become east or southeasterly overnight as
converging outflow boundaries descend on the Phoenix area. However,
latest guidance suggests winds will not be very strong as the
boundaries move through. Some isolated showers and thunderstorms are
also possible overnight, though significant impacts at the terminals
are unlikely. More of the same expected for Sunday, with the best
chance for showers and thunderstorms across the higher terrain north
and east of Phoenix with the possibility of an outflow boundary
reaching the valley during the evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather impacts anticipated. Winds will generally retain
a southerly component through Sunday at both KIPL and KBLH,
occasionally reaching as high as 15 kt.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Tuesday through Saturday... Moisture values will remain quite
elevated through the entire week yielding good to excellent chances
for at least some wetting rains. Thunderstorm coverage will be more
extensive during the first half of the week with occasional gusty
winds and heavy rainfall. More regular thicker cloud cover will also
keep temperatures near to below normal during the week; and
scattered rainfall will force humidity levels above normal. Minimum
humidities in the 25-50 percent range early in the week will drop to
around 15-30 percent by the end of the week. Overnight recovery will
be good to excellent. Outside of thunderstorm wind gusts, wind
speeds will be typically light throughout the day.

&&

.SPOTTER INFORMATION STATEMENT... 
Spotter activation could be possible later today.

&&

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

$$

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DISCUSSION...AJ 
AVIATION...Hirsch 
FIRE WEATHER...Percha