Forecast-Discussion

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FXUS65 KPSR 041156
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
456 AM MST Sun Dec 4 2016

.UPDATE...Updated Aviation and Fire Weather Discussions...

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.SYNOPSIS...
Seasonable temperatures and passing high clouds can be expected
across the region the next few days. Another storm system will pass
to the north late Tuesday into Wednesday bringing a slight dip in
temperatures and breezy conditions. Temperatures will rebound once
again towards the end of the week.

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.DISCUSSION...
Dry subsident flow predominates across the Desert Southwest in the
wake of an upper low that moved south of the region through northern
Mexico Saturday. Axis of a ridge extending from the eastern Pacific
will be draped across the area today, resulting in mostly sunny
skies, light winds and near normal temperatures.

Pattern will transition Monday as the flow becomes increasingly
cyclonic across the western half of the country. A broad trough will
descend from Canada bringing a much colder air mass to mainly the
central Plains through the week. Operational models still remain in
good agreement that a short-wave trough will pass by to our north
Wednesday. Latest ECWMF suggests forcing for ascent will be
sufficient to generate scattered showers mainly across northeastern
Arizona, while the GEFS plumes continue to show little potential for
precipitation. Official forecast is for a 10 percent PoP across
eastern Gila County. Main impact from this system will instead be a
brief cooldown, with temperatures dropping a few degrees below normal
Wednesday and Thursday.

Behind the aforementioned trough, a ridge will build across the
intermountain West late in the week followed by zonal flow for the
weekend. Activity across the western states will mainly be
concentrated across the northern latitudes with little impact in
terms of sensible weather across the Southwest. Temperatures will
remain near or slightly above normal with no chance of precipitation.

&&

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

Mostly clear skies and dry conditions forecast for the TAF period.
Overall light winds will prevail across the area through Monday
morning...generally following typical diurnal patterns. No aviation
impacts expected at least through Monday morning.

Aviation discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Tuesday through Saturday:
Near normal temperatures and mostly dry conditions are likely for
next week. A passing weather system to the north late Tuesday into
Wednesday will bring breezy northerly winds down the Lower Colorado
River Valley on Wednesday. Other days will feature mostly light winds
with occasional afternoon breeziness. Minimum humidities on Tuesday
will range from 30 to 40 percent, but then drop starting Wednesday
with readings down into the teens to 25 percent.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters are encouraged to report according to standard criteria.

&&

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

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DISCUSSION...Hirsch
AVIATION...Kuhlman
FIRE WEATHER...Kuhlman

NWS PSR Office Area Forecast Discussion