000
FXUS65 KPSR 290506
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1006 PM MST Tue Jun 28 2022

.UPDATE...UPDATED 06Z AVIATION DISCUSSION.

&&

.SYNOPSIS...
Thunderstorm activity may return to parts of lower elevations
Wednesday, however the trend will be towards coverage retreating
into higher terrain areas and becoming more sparse late this week
and early next week. Nevertheless, gusty winds and blowing dust
should be the primary impacts for most locations. Temperatures will
be a few degrees above average the next couple days, however should
settle back to near normal by the end of the week.

&&

.DISCUSSION...
A pronounced high pressure center has migrated into far northern AZ
with subsident northerly flow spreading into the forecast area.
Meanwhile, the combination of TD Celia and a multi-centered inverted
trough over northeast Mexico was creating a deformation/shear axis
through far southern AZ. Climatologically abnormal high moisture
content continues to hover over much of south-central AZ with a
solid pool of 9-10 g/kg mixing ratios in the sfc-H7 layer. Despite
this favorable moisture availability, warming temperatures through
the midtroposphere in response to the ridge behavior should be
enhancing CinH through the afternoon. In combination with more
unfavorable ascent structure, essentially all model output suggests
little convective activity developing or propagating into the CWA
this afternoon, rather becoming more focused along the international
border where favorable upper level divergence and less inhibition
become juxtaposed. That said, a few storms should develop in the
most favored initiation points (i.e. Kofa range, Table Top
Wilderness, Pinal Peak, etc.), but likely not be sustained much away
from the forcing terrain features.

Northern AZ high pressure will continue to progress eastward on
Wednesday placing the forecast area within a more southeast flow
regime and bringing better upper level support closer to the area. A
handful of CAMs suggest the potential for at least one MCV or piece
of an easterly wave to be absorbed into the flow and spurring moist
midlevel ascent at some point during the day. This could be in the
form of localized elevated morning accas showers/storms through
western AZ, or possibly a slower moving feature awaiting better deep
layer instability during the afternoon. Regardless, HREF membership
is somewhat less enthusiastic about concentrated storms propagating
into lower elevations though forecast BUFR soundings indicate very
little inhibition collocated with ample instability (MLCape ~1000
J/kg and DCape ~2000 J/kg). Any storms that can survive into lower
elevations will carry strong gusty winds and blowing dust as the
main impacts though HREF probabilities of 35 mph winds have fallen
into a 50/50 proposition for any given point in south-central AZ.
Accumulating rainfall will be more difficult to come by with NBM
odds of even reaching 0.10" barely exceeding 30% for anywhere within
the CWA (no more than 15% chance anywhere in the Phoenix metro).

Ensemble members are in somewhat better agreement during the end of
the week with respect to the magnitude and influence of growing
southwest flow as ridging returns to the southern plains and deep
troughing approaches the California coast. Model trends continue to
show a slow erosion and eventual dislodging of quality moisture
resulting from the flow pattern; however historically and within
some current models, once deeper moisture mixed through the boundary
layer becomes established during the monsoon, it becomes more
difficult to rapidly scour it away. However, required NBM POPs drop
off quite quickly by Thursday and Friday restricting any storm
chances to essentially only to the far eastern CWA. That said, it
would not be surprising if one day over the weekend provides a
better opportunity for stronger outflow winds and a few isolated
storms outside of higher terrain locations. Better agreement exists
that the moisture plume will be dislodged into New Mexico early next
week and thunderstorm chances diminish even further.

&&

.AVIATION...Updated at 0505Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Light southeast winds will be present throughout the night. Winds
will attempt to shift to southwest by Wednesday afternoon. At that
time scattered storms will develop, possibly over the metro area,
leading to erratic wind shifts and gusty winds. Strong winds and
blowing dust will be the primary threats in addition to the
lightning potential. Probability of >30 kt winds is up to 40-60%.
FEW-SCT coverage above 10kft will be common.

Southeast California/Southwest Arizona including KIPL and KBLH:
At KIPL, westerly wind this evening will become south to southeast
by sunrise Wednesday. At KBLH, south to southwest will be the
predominant wind direction with speeds of 8-15 kts. Skies will be
mostly clear, but a very isolated storm could develop on Wednesday
afternoon near KBLH.

&&

.FIRE WEATHER...
Thunderstorm coverage may increase Wednesday into lower elevations
of Arizona though western districts will most likely remain dry.
Storms will generally retreat into the higher elevations of eastern
districts later in the week, and may exit the region next week as
drier air overtakes much of the area. Nevertheless, the main impact
of any storm will be strong winds and lightning with only limited
areas receiving wetting rainfall.

Minimum humidity values will generally range from 15-30% much of
this week, then decrease closer to a 10-25% range next week.
Overnight recovery will generally be 25-50% over lower elevations
and 50-80% over the higher terrain of eastern districts. Increased
southwest winds will begin to become more common over western
districts this weekend, but remain well below critical thresholds.
Otherwise aside from thunderstorm outflows, winds in eastern
districts should not pose problems.

&&

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

$$

DISCUSSION...18/AJ
AVIATION...Hodges/Benedict
FIRE WEATHER...18/AJ

NWS PSR Office Area Forecast Discussion