Forecast-Discussion

000
FXUS65 KPSR 192123
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
223 PM MST Tue Sep 19 2017


.SYNOPSIS...
Dry air over the Southwest will persist through Wednesday as
temperatures remain near seasonal normals across southeast
California and southern Arizona. A strong and expansive area of
low pressure will develop over the Western U.S. during the latter
part of the week bringing cooler temperatures, breezy conditions,
and the chance for showers and a few thunderstorms to eastern
portions of Arizona for Thursday and Friday. Well below normal
temperatures and dry conditions will move in across the region
this weekend.

&&

.DISCUSSION...
Not much change in intermediate forecast as southwesterly flow aloft
continues to supply plenty of dry air over the region. Mostly clear
skies and near seasonal normal temperatures will continue through
Thursday. Today`s forecast calls for highs near 100 degrees for the
lower desert with lows near 70. Then rinse and repeat, more or less,
through Thursday. Thursday afternoon and evening does look to be
rather breezy with gusts 20-30 miles per hour as a front
associated with a strong Pacific trough approaches from the west.

The best weather in months, temperature wise, will begin to take
root Friday and last through the weekend as the trough progresses
through the region. On Friday, temperatures for many lower desert
locations should sink a little below the 90 degree mark.
Meanwhile, overnight lows will definitely be "open window weather"
with temps in the 60s. The chance for precipitation with this
system will leave much to be desired leaving the higher terrain
with the best opportunity for rain.

Otherwise, dry westerly flow and continued cool conditions are in
store for the region at least through the weekend and mostly
likely into early next week. We should see temperatures start
climbing back toward normals or even slightly above normals
starting the middle of next week.

&&

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

Minimal aviation concerns through the TAF period under mostly clear
skies. Wind shifts will follow typical diurnal headings and speeds
should not be a major issue with only a few gusts up to 20kt
possible this afternoon and tomorrow afternoon.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Friday through Tuesday:
Persistent low pressure over the Great Basin will keep flow aloft
mainly out of a west to southwest direction through Sunday before
switching to a more northwesterly direction Monday through
Tuesday. A modest increase in moisture will occur Thursday through
Friday, bringing a slight chance of thunderstorms primarily to
southern Gila County. Dry conditions return Saturday through
Tuesday. Much cooler temperatures will arrive Friday behind a cold
front, falling to around 10 degrees below normal for the date.
Humidities to fall mainly into the 15-30 percent range with good
overnight recoveries.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

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

$$

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DISCUSSION...Deemer/Kuhlman
AVIATION...Hernandez
FIRE WEATHER...Hernandez

NWS PSR Office Area Forecast Discussion