061 
FXUS65 KPSR 132349
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
449 PM MST Thu Jan 13 2022

.UPDATE...Updated Aviation Discussion. 

&&

.SYNOPSIS...
Overall dry conditions, periods of clouds, and above normal 
temperatures will persist through at least early next week. A weak 
upper level disturbance passing by the region on Friday will bring 
thicker clouds followed by breezy conditions later Friday into 
Saturday. The weather pattern will essentially be stalled through 
early next week providing little day to day change in temperatures 
and highs mostly in the lower 70s across the lower deserts.

&&

.DISCUSSION...
Satellite and objective analysis this afternoon shows a ridge axis
over the Gulf of California and up through Arizona. Deep southerly
flow is seen on the west side of this ridge with high clouds
continuing to stream north into the Southwest. The ridge has also
led to another degree or two of tropospheric warming from
yesterday, as indicated by aircraft soundings, and surface
temperatures so far today have been warming slightly quicker than
yesterday. Still anticipating highs today to top out in the low-
70s.

The most identifiable feature on water vapor this afternoon,
across the western CONUS, is the low that has rounded the north
side of the eastern Pacific rex block and has now pushed inland
into the PacNW. Satellite shows this low is currently
transitioning to an open shortwave and has already taken on a
positive tilt. This shortwave is expected to quickly dig 
southeast through the Great Basin and Four Corners area, clipping 
through Arizona, through Friday. With this trajectory, the overall
sensible impact to the local area will be minimal. While 500 mb
heights will lower, surface temperatures are not expected to lower
much, if at all. NBM forecast still has highs near the 70 degree
mark for the lower deserts through this weekend. 

The one impact worth mentioning is a strong north to northeast 
gradient wind Friday night into Saturday as strong high pressure 
develops in the Great Basin following the shortwave. This should 
lead to breezy conditions in Arizona on Saturday. Forecast 
soundings show the strongest winds, upwards of 40-45 mph, will be 
mostly in the 850-700 mb layer and during the overnight hours. 
This will likely limit the strongest surface gusts to the higher 
terrain/ridges north and east of Phoenix. The ECMWF EFI is showing
the potential for a seasonably anomalous wind event in central 
Arizona and HREF is indicating lower desert surface gusts up to 
20-30 mph will be common Saturday, especially in the morning, 
while ridges and mountain tops could see gusts up to 45-55 mph.
Breezy north winds are also expected in SoCal beginning Friday
afternoon. So, caution should be taken if planning to recreate
outdoors Saturday, especially in mountainous areas of south-
central Arizona Saturday morning.

As far as precipitation chances over the next several days, there
is not much to speak of. NBM probabilities of measurable
precipitation anywhere in the CWA through early next week is under
10%. EPS and GEFS do show the best push of moisture into the 
region over the next 7 days will actually be tonight through 
Friday, with IVT peaking briefly around 250 kg/ms. Ensembles show 
great consensus on this, but also still keep higher moisture 
content to the south and maintain a very dry layer subcloud layer,
below 700 mb, through this period. Increased cloudiness and lower
clouds, along with virga radar echoes, are expected. Maybe some 
rogue rain drops, but again the chance of measurable rain is very 
low (under 5%). The mid-levels dry out following the passage of 
the trough from the northwest later Friday.

.PREVIOUS DISCUSSION...
The rest of the weekend into early next week should see the cut- 
off low weakening further as it most likely drifts from just off 
the southern CA coast through our region some time early next 
week. Model ensembles continue to trend drier with this most 
likely scenario with the NBM now showing less than 10% PoPs 
through the first half of next week. Likely the only impact with 
this weak system passing through our region will be another round 
of clouds. NBM forecast temperatures for the first half of next 
week change very little with highs generally ranging from the 
upper 60s to lower 70s, or a few degrees above seasonal normals. 

&&

.AVIATION...Updated 2345Z. 

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

An upper low centered off the northern Baja peninsula will spread
increasing cloudiness over the region today and tonight. Mid-level
CIGs will lower to 10-15 kft late tonight from west to east. 
Periods of virga and sprinkles are also likely from late tonight 
through Fri afternoon. Clouds decrease Fri afternoon over the 
Phoenix area but linger over SE CA. Surface winds will remain 
light (AOB 7kts) and favor diurnal patterns through the daytime 
Friday. Otherwise gusty N winds are expected to develop at KBLH by
mid Fri afternoon with gust of 20-25 kts likely. 

&&

.FIRE WEATHER... 
Saturday through Wednesday: 
Dry weather with warmer than normal temperatures are expected
through the first half of next week. A couple weak upper level
disturbances are likely to bring periods of clouds and maybe some 
isolated very light showers, but chances for wetting rains are 
generally less than 5%. Minimum afternoon humidity levels will 
mostly fall into a 15-25% range following fair to good overnight 
recovery around 30-55%. Winds will start off breezy on Saturday, but 
are expected to be fairly light through the rest of the period.

&&

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

$$

DISCUSSION...Benedict
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Sawtelle/AJ
FIRE WEATHER...Kuhlman