Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 282119

Area Forecast Discussion
National Weather Service Phoenix AZ
215 PM MST WED SEP 28 2016

A low pressure system over northwest Mexico will continue to slowly
move north through the Desert southwest into Thursday, resulting in
variable cloudiness, cooler temperatures, and a threat of showers
and thunderstorms. Dry and stable weather will return Friday through
early next week with seasonably warm temperatures.



Tonight through Thursday night...

Broad cyclonic circulation over the region continues as remnants of
the former large Baja CA low pressure system moves through the area.
At the moment convergent upper level winds have suppressed activity
a bit over an increasingly moist flow from Mexico. A slight chance
of diurnal showers and perhaps a thunderstorms is still possible
through this evening, mainly over southern Gila County.

Otherwise the next potent shortwave trof, currently seen in water
vapor satellite imagery 500 miles southwest of San Diego, is still
forecast to move into parts of southeast CA, and southwest and south
central AZ early Thursday morning through early afternoon. Best
dynamics again appear to be over southwest AZ and Colorado River
Valley where precip probabilities are the highest Thursday morning.
A lingering threat of showers will continue over our forecast area
Thursday afternoon and early evening as this system quickly moves
into northwest AZ.


Appreciable low level moisture and high humidity will linger over
southwest and south central AZ Friday, however a more stable
westerly flow pattern is expected. Any shower threats will be
relegated to the mountains of southern Gila County Friday afternoon
and evening. Partly cloudy elsewhere.

Saturday through Wednesday...

Low level moisture will finally start to decrease from the west this
weekend under west and southwesterly flow aloft at all levels. A
much drier airmass will arrive Monday through Wednesday. Therefore
mostly clear skies and seasonably warm temperatures are expected.



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

A chance for storms in the area but mostly to the east and southeast
of the terminals. The winds will continue to maintain an easterly
component before switching somewhat southerly. There is uncertainty
as to whether or not the winds will shift west at all.

Southeast California/Southwest Arizona including KIPL and KBLH:

The winds will be rather variable through the day and evening before
moving to a more southerly direction. Otherwise, do not anticipate
any other weather related impacts to aviation.


Saturday through Wednesday... Chances for storms will greatly
diminish as a southwesterly flow aloft brings in drier air into the
region. Minimum humidities for the lower deserts will drop below 15
percent and down to about 20 percent for the higher terrain in Gila
County. The overnight recoveries look to be decent to 30-45 percent.
Conditions look to be breezy at times, especially Sunday and


Skywarn radio Net activation will not be needed.




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