Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 100215
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
715 PM MST Fri Dec 9 2016

.SYNOPSIS...
Dry weather with seasonably comfortable temperatures will persist
through the weekend and into at least the middle of next week. Only
periods of passing high clouds will interrupt an otherwise beautiful
stretch of early winter weather while no precipitation will affect
communities into next week.

&&

.DISCUSSION...
Quasi-zonal flow persists across the East Pacific basin pushing
batches of thicker cirrus onshore into the SW Conus. While 00Z
sounding data showed little change in H5 heights, rather significant
2C-4C of warming was sampled in the sfc-H7 layer yielding afternoon
highs some 1F-5F warmer than Thursday. This warmer boundary layer
and extensive cirrus cover has already retarded nocturnal cooling
with readings some 2F-6F above this time last evening. While clouds
will thin with time overnight, overnight lows should still remain
above a persistence level forecast. A couple minor changes were made
in the evening update accounting for the aforementioned cloud and
temperature trends, but the overall weather message of tranquil
weather continues through the weekend.

&&

.PREVIOUS DISCUSSION...
/205 PM MST Fri Dec 9 2016/
Very little change in the overall pattern is expected through at
least the middle part of next week. Model consensus continues to be
outstanding through the entire period with all of the global model
suites; and the vast majority of their respective ensemble members
keeping the SW US under flat ridging and dry west-northwesterly flow
aloft with little day-to-day change in temperatures. Lower desert
highs are expected to rise into the low-mid 70s each day. Skies will
remain mostly clear most days with just some high cloudiness passing
over the region Saturday night and Sunday as a shortwave passes to
to our north across the Great Basin and into the central Rockies.
The only impact from the high cloudiness is to keep our overnight
lows elevated a bit on Saturday night/Sunday morning with many low
desert locations seeing lows up in the low-mid 50s that night.

There does appear to be a change coming in the weather pattern, but
it will likely arrive after the end of the current 7 day forecast
which will be next Friday into the following weekend. Although
spaghetti ensemble members are very jumbled, preponderance of
guidance suggests a deep trof will set up over the western CONUS by
next Friday leading to a chance of showers, much cooler high
temperatures, and the potential for some very strong winds
especially over the western deserts. We will be keeping a close eye
on this developing shift in the weather pattern in the days ahead.

&&

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

There are no weather concerns for aviation interests through Saturday
afternoon. Only passing thin high cirrus cover will affect terminal
sites. Winds will favor typical diurnal directional patterns while
remaining light through the TAF period (in many cases, prolonged
periods of nearly calm conditions).

Aviation discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Sunday through Thursday:
There are no significant fire weather concerns for the period.
Slightly above normal temperatures and mostly dry conditions are
will persist with high clouds moving across the area at times. Winds
each day will mostly stay on the light side with typical afternoon
breeziness favoring the southwest or west. Humidities will be
elevated through the five day period with minimum RH values mostly
between 20 and 30 percent each day with great recoveries.

&&

.SPOTTER INFORMATION STATEMENT...
Spotter activation will not be needed through the middle of next
week.

&&

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

&&

$$

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DISCUSSION...MO/Percha/CB
AVIATION...MO
FIRE WEATHER...CB/Deemer



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