Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 07/04/20

Area Forecast Discussion

National Weather Service Phoenix AZ

 506 PM MST Fri Jul 3 2020

.UPDATE...
Updated Aviation discussion.

&&


.SYNOPSIS...
A slight chance of isolated showers and thunderstorms will linger
around Phoenix and parts of the lower deserts through early to mid
afternoon. As high pressure builds into the region, a warming trend
will allow highs to climb back above normal by this weekend, and
continue well into next week. Also a drying trend will not favor
storm development for the holiday weekend or through the early part
of next week. A lack of significant moisture for the rest of next
week will also help to maintain dry conditions.

&&

.DISCUSSION...
Yesterday`s disturbance that came up from the south only produced
very isolated and modest area precipitation south and southwest of
Phoenix along with some locally gusty outflow winds. However it also
ushered in a regional wall of very moist air into AZ, including
S-Central AZ. The 12Z Phx sounding showed the moistest airmass so
far of the Monsoon season with a PW that increased to 1.69",
mixing ratio of 11.3 gm/kg and MUCAPE of 567 j/kg. The moist,
moderately unstable airmass combined with a very thin, weak mid
tropospheric disturbance SW of Phoenix to produce some very
isolated showers this morning near Gila Bend and SW Maricopa cty.

Most of this mornings HREF members indicated a chance of isolated
showers and a couple of embedded storms in and around Phoenix and
Gila Cty through about early to mid afternoon and becoming
increasingly isolated for the later half of the afternoon. As a
result expect a lingering slight chance of isolated showers and a
storm for this afternoon. Midday ACARS Phx soundings indicated a
CAP near H5 (that had increased since 12Z) that is making it
difficult for the patchy CU field SW to S of Phoenix from growing
much since the end of the isolated morning showers there. A
gradual drying trend is also underway with PWs already decreasing
with drier air beginning to move into the region. By late
afternoon to early evening expect the chances for convection to
rapidly diminish as high temperatures top out just below normal
near 105. However the scattered storms in the N AZ high country
will wait until the evening before tapering off.

A warming trend gets underway on Saturday as the ridge continues to
work its way west closer to the region and with the continued influx
of drier air. Above normal highs will climb to near 108 to 110 by
Saturday and remains near 110-111 through Tuesday.

The gradual drying trend will last until around Sunday night to
early Monday as the ridge axis retrogrades further to the W-SW. A
modest increase in moisture for early next week will likely not be
enough to dampen the very hot temperatures or to increase any storm
chances. Moisture and instability along the S flank of the ridge
will keep the best storm chances confined mostly to SE AZ and NW MX
for next week.

&&

.AVIATION...Updated at 0006Z.

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

Storm activity this afternoon has been limited to the northern
half of AZ with only FEW-SCT cumulus and some modest towering
cumulus over/near the Phoenix metro area. This will most likely
continue to be the case with a decline of those clouds as surface
heating wanes. However, the atmosphere over the metro area has
some untapped potential for a thunderstorm to develop. So, the
possibility of a storm developing in the vicinity of one or more
TAF sites can`t be ruled out entirely. But, confidence too low to
reflect in the TAFs. Winds aloft through much of the troposphere
are west and southwest and will be that way through Saturday.
Surface winds will continue to favor westerly directions through
this evening before slowly trending to downvalley/drainage
patterns (favoring easterly directions). Anticipate development of
southeast and southerly winds late morning and early afternoon
before trending toward westerly.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds aloft will continue to be southwest and westerly though
Saturday with clear skies (some minor flat cumulus east of the
Lower Colorado River Valley). Surface winds will continue to
follow familiar diurnal patterns with afternoon breeziness most
noticeable over the Lower Colorado River Valley.

&&

.FIRE WEATHER...
Monday through Friday:
Overall, conditions will be hot and dry. Daytime minimum humidity
values will drop below 15% for most places while overnight
recoveries will rise into the 20-40% range. Wind speeds will
generally be light, outside of typical afternoon breezes, with
directions following local terrain influences. Moisture will
mostly be insufficient for thunderstorms but a few isolated cells
may form on any particular day, primarily over the White Mountains
and in southeast Arizona. As of now, these locations seem too far
to send any outflow winds into south-central Arizona.

&&

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

&&

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

$$

DISCUSSION...Sawtelle
AVIATION...AJ
FIRE WEATHER...Sawtelle/AD