Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 292139

Area Forecast Discussion
National Weather Service Phoenix AZ
239 PM MST MON AUG 29 2016

Moisture will increase from east to west Tuesday and Wednesday. Storm
chances expand to the lower deserts...east of the Lower Colorado
River Valley...on Wednesday and Thursday. A drying trend is then
likely Friday through the weekend as a low pressure system moves
through the western states. Temperatures will very slowly
decrease...remaining above normal this week for southeast California
and portions of southwest Arizona.


Rest of Today...
Satellite imagery shows just some flat Cu over the higher terrain
this afternoon. There may be a stray storm or two that yet develop
near the New Mexico border but otherwise, no storms for our forecast
area. There could possibly be some debris clouds from northwest New

Tuesday through Thursday...
Models depict amplification of the flow pattern over the CONUS and
northeast Pacific which includes an expansion of a ridge that extends
across California, the Great Basin, and western AZ as well as a
westward expansion of the high centered near Kentucky. In the
process, the upper low centered roughly over western Colorado weakens
and merges into a larger upper low/inverted trough centered near
southern Sinaloa Mexico. This allows westward moist advection and
associated CAPE (though not abundant amounts). Storm chances will
return to the higher terrain of south-central AZ on Tuesday then
expand to the lower elevations for Wednesday and Thursday (but
remain east of the Lower Colorado River Valley). A couple of waves in
the southerly steering flow may help in storm development Wednesday
and Thursday (though moisture availability over our area is not
overwhelming). This flow pattern also makes blowing dust from
southeast Arizona more likely as well.

Friday through Monday...
Operational models continue to indicate that moisture will scour out
from west to east as two anomalous troughs move eastward through the
western CONUS beginning Friday. Timing differences still abound,
though the general trend will be towards drier conditions.


South-Central Arizona Including KPHX, KIWA, and KSDL:
Winds will remain mainly out of the east. Skies will remain mostly
clear with a few clouds AOA 10kft.

Southeast California/Southwest Arizona including KIPL and KBLH:
Skies will remain clear and winds will remain light, following
typical diurnal trends.

Aviation Discussion not updated for amended TAFs.


Thursday through Monday...
Storm chances continue east of the Lower Colorado River Valley
Thursday. The end of the week and weekend will have a downtrend in
storm chances as drier air moves into the region. Accordingly,
humidities decline as well with minimum RH values dropping by 5-10%.
Overnight recovery will remain fair to good. Afternoon and evening
wind speeds will trend upward, favoring typical upvalley patterns, but
no widespread strong wind events are anticipated.


Spotters should follow standard reporting procedures.




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