000
FXUS65 KPSR 121101
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
401 AM MST Tue Nov 12 2019

.UPDATE...Updated Aviation Discussion...

&&

.SYNOPSIS...
A quiet weather pattern will continue to bring dry weather with
above normal temperatures and periods of high clouds this week.
Winds will generally be light except today when a weak back door
cold front moves into the region from the east. Lower desert high
temperatures will decrease slightly from the mid 80s to lower 80s
behind this front, with lows in the 50s and lower 60s.

&&

.DISCUSSION...
Early this morning, high pressure aloft could be seen building into
the desert southwest from the west; latest 500mb plots indicated 20-
30m height rises across Arizona and north to northeast flow aloft
continued to spread drier air into the area. Current IR imagery
showed generally clear skies area wide and surface dewpoints over
the central deserts were down several degrees or more over the past
24 hours, ranging from the mid 20s to upper 30s. Despite the
influence of high pressure aloft building in from the west, a
backdoor cold front will be pushing into the area from the east
today, leading to rather breezy east winds (especially across south-
central deserts) and cooler high temperatures across the central
deserts including the greater Phoenix area. Highs will fall to about
80 degrees today while the western deserts into far southeast
California will stay in the mid 80s. Very little change in the
pattern is expected Wednesday with minimal temperature changes,
although winds will be down sharply.

For the remainder of the forecast period, generally all signs
continue to point to a dry forecast period with little or no weather
impacts. Latest NAEFS POPs remain generally zero or low single
digits through the weekend across southern Arizona, there are no
signs of any IVT processes bringing moisture into the area, GEFS
plumes for Phoenix keep almost all of the members flat lined at 0.00
for the next 7 days and GEFS GFS ensemble members are almost
completely in agreement that no measurable rain will occur mid week
into early next week. There are no significant temperature changes
expected day to day, with lower deserts generally ranging from the
low to middle 80s each day. Above normal high temperatures will be
the rule for the rest of the forecast period.

The only weather impact of interest is in the form of cloud cover.
Starting later Wednesday and continuing thru the end of the work
week, the upper ridge will weaken a bit as an open wave trof slowly
approaches the west coast and then begins to move inland.
Considerable high cloudiness will spread across the deserts Thursday
into Friday ahead of the wave. By Friday afternoon, latest model
runs split the trof, allowing the northern portion to move inland
and across the area Saturday as a dry open wave, and the southern
extent becomes a closed low which migrates to the southwest and off
the northern Baja Coast. Later on Saturday, a dry subsident north
flow aloft behind the exiting trof will bring sunny skies back to
the lower deserts. High pressure aloft building back into the area
from the west will keep sunny days and clear nights going into the
early part of next week.

&&

.AVIATION...Updated at 1100Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Persistent and occasionally gusty east winds will be the main
aviation impact through late this afternoon under mostly clear
skies. Gusts 15-20kt likely will not materialize until mixing
occurs during the middle part of this morning, lasting through
around mid afternoon before winds diminish. Confidence is
excellent that east winds will persist the entire day today and
through tonight.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns through early Wednesday under clear skies.
Winds will be light and variable for prolonged periods, but will
generally favor a west component at KIPL and a N/NE component at
KBLH.

&&

.FIRE WEATHER...
Thursday through Monday:
Relatively dry conditions will persist through the period with
increasing high pressure aloft through the work week. Above normal
high temperatures will persist across the lower deserts each day
with warmer deserts mostly in the low to mid 80s. Look for light
winds following diurnal trends expected for the rest of the week.
Minimum relative humidity values will fall into the mid to upper
teens each day across southeast California and southwest Arizona
while remaining above 20 percent over south central Arizona.

&&

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

&&

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

$$

DISCUSSION...CB
AVIATION...MO/Kuhlman
FIRE WEATHER...Hopper/CB

NWS PSR Office Area Forecast Discussion