Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 07/01/22

Area Forecast Discussion

National Weather Service Phoenix AZ

 458 PM MST Thu Jun 30 2022

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS... Although there is still a minor risk for gusty
outflow winds across lower elevations Friday, chances for showers
and thunderstorms will decrease moving east through the weekend.
By Saturday, most areas will see little to no rain chances; and
this dry pattern will likely persist through at least the fist
half of next week. Temperatures will remain near normal through
the holiday weekend, then trend up later next week.

&&

.DISCUSSION...
A mid-level anti-cyclone continues its transit eastward into the
southern plains with the plume of monsoonal moisture/instability
on its western periphery covering roughly the eastern 1/2 of
Arizona early this afternoon. Within the southerly flow through
central and northern AZ, three distinguishable MCVs have been
traversing through the flow invigorating accas development and
light showers through eastern parts of the state. Morning ACARS
soundings indicate southwesterly flow becoming a bit more
established across the region within the H8-H7 layer, and
subsequently, boundary layer mixing ratios were dropping closer to
a 8-10 g/kg level.

Along with the ascent from the various MCVs, this residual modest
moisture was allowing diurnal convection to be focused over mountain
locations of eastern Arizona. Conceivably, enough instability and
limited CinH will remain over the nearby foothills for some outflow
backbuilding to occur, however there is little evidence supporting
deep convection over lower elevations. 12Z HREF probabilities have
dropped even lower than the 00Z iteration with mandated NBM POPs not
even exceeding 15% away from foothill locations. Once again
today, gusty outflow winds would be the greatest impact, though
almost certainly with less depth and organization as Wednesday
given the paucity of lower elevation updraft/downdrafts and
distance traveled from storms over the mountains. An almost
identical pattern will exist Friday except with less moisture and
the convective focus shifting further east in the White Mountains
and south into Sonora.

An upper level low off the West Coast is anticipated to become
broader, but slightly retrograde while the anti-cyclone over the
Southern Plains expands during this weekend and into early next
week. The result will be a deeper southwest flow that incorporating
more dry air and dislodging the better quality moisture plume
eastward, possibly all the way into New Mexico. Several model
suites suggest boundary layer mixing ratios falling below 8 g/kg,
generally too low to support deep convection in all but the most
favored mountain areas. Thus, rain chances for most if not all of
the CWA through the holiday weekend taper off substantially with
notable POPs over 10% merely relegated to Gila County.

By late next week, uncertainty in global ensemble data is mostly
focused on retrogression of Conus features and subtropical ridging
strengthening back over the western US. There is a growing number of
deterministics and ensemble members forecasting H5 heights
exceeding 600dm building near the four corners by next weekend,
and even the NAEFS ensemble mean paints a 598dm anti-cyclone
center right over SW Colorado. NBM-based probability for 110+ F
high temperatures rise above zero percent starting Wednesday for
most lower desert communities, and increase to 40-80% into the
weekend. Should this ridge build further to the north and west
with more constricted circulation, better easterly flow and
influence from inverted troughs could aid in bringing thunderstorm
activity back into the forecast area by the end of next week. On
the other hand, a more expansive ridge dipping into central
Arizona would portend a forecast dealing with a period of
excessive heat prior to nay better moisture return.

&&

.AVIATION...Updated at 2355Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Medium strength W component winds with some gusts into the teens
will subside during this evening. Outflows from the distant storms
may turn winds E as early as 3-6Z. Otherwise it is more likely not
to occur until 10-12Z. An earlier than normal SW-W switch comes by
mid-late morning followed by breezy conditions and some gusts of
17-22 kts by mid afternoon. Skies to remain clear to partly cloudy
with FEW/SCT mid-high decks from 9-25kft.

Southeast California/Southwest Arizona including KIPL and KBLH:
Typical diurnal wind tendencies are expected at both terminals
with SE winds at KIPL shifting W late this afternoon with another
round of breezy downsloping/sundowner winds with some gusts
upwards of 25 kts. Winds will favor the S components at KBLH with
afternoon gusts up to 20-25 kts. Isolated storms may develop over
the mountains in Mexico this afternoon, to the W and SW of KIPL,
but should dissipate quickly after pushing off the mountains and
not reach the terminal. At most an outflow boundary may reach the
terminal.Otherwise expect mostly clear skies.

&&

.FIRE WEATHER...
Shower and thunderstorm potential will be shifting into far eastern
Arizona through the weekend with even limited chances of wetting
rainfall in eastern districts early next week. With temperatures
hovering not far from the seasonal normal, humidity values will
generally trend lower with afternoon values falling closer to 10-20%
as storm activity decreases. Overnight recovery should mostly range
from 25-40% except somewhat higher over mountainous areas.
Southwesterly winds will also increase in strength through the
weekend particularly across southeast California and southwest
Arizona though all areas will remain below critical thresholds.

&&

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

$$

DISCUSSION...18/Iniguez
AVIATION...Sawtelle/Benedict
FIRE WEATHER...18/Iniguez