Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/18/20

Area Forecast Discussion

National Weather Service Phoenix AZ

 527 PM MST Sat Oct 17 2020

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Temperatures will remain in the mid to upper 90s the next several
days but will begin to decline by next weekend. There will be
very little cloudiness through the next week. However, smoke from
wildfires, emanating mainly from California, will create varying
amounts of hazy skies this weekend.

&&

.DISCUSSION...
Current visible satellite is completely clear across all of
Arizona and most of the southwestern USA. High pressure remains in
control of the weather pattern and is currently centered
southwest of the area, leading to continued dry westerly flow
aloft through the entire column. ACARS soundings show a meager
0.29 inch PWAT at present. In spite of the very stable conditions,
smoke in the upper levels from California continues to slightly
dim the sky. With westerly flow, smoke from the Horse Fire in
Yavapai County is now largely moving east and away from the
Phoenix area. High temperatures today will be a few degrees less
than yesterday and should remain below 100 degrees.

Forecast models have been indicating that the continental trough
centered over south-central Canada would slowly expand westward
and southward over time. However, the latest guidance diminishes
and delays this trough expansion until the end of next week now.
This should translate into continued mid to upper 90s for the next
several days with little cloud cover. By the end of next week a
series of shortwave troughs will help to carve out a deeper
western trough. At present all indications are that this will be
a dry feature for our CWA, but some intrusion of cooler air
appears to be the most likely outcome. As we have been saying for
the last several days, there remains considerable uncertainty in
terms of timing and intensity of the cooler air, and this does not
look likely to change anytime soon with a very large spread
amongst all the ensemble systems.

&&

.AVIATION...Updated at 0010Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Mostly light winds will continue to show typical diurnal
directional patterns through the period. The easterly switch will
occur early this evening. Smoke and haze from distant wildfires
will create slantwise visibility issues along with SCT-BKN decks
near 18-25 kft across the region through the period.

Southeast California/Southwest Arizona including KIPL and KBLH:
Winds will be light and favor variable directions. Smoke and haze
from distant wildfires will create slantwise visibility issues
along with SCT-BKN decks near 18-25 kft across the region.
Localized smoke and haze with visibilities occasionally reduced to
5 sm are expected for KIPL. Some very breezy westerly winds will
also occur at KIPL for several hours beginning late Sunday
afternoon with some gusts upwards of 20 kts.

&&

.FIRE WEATHER...
Tuesday through Saturday:
Dry northwest and west flow will continue through next week.
Temperature trends will be flat through most of next week with
lower desert highs in the upper 90s followed by modest cooling
into the low- mid 90s towards the weekend. Humidities will remain
low during the first half of the week with Min RH readings in the
10-15% range at most locations (Max RH values generally 20-35%).
Humidities are anticipated to trend upward late in the week with
Min RH readings increasing to 15-20% most places by Friday (Max RH
generally 35-55%). Winds are expected to remain light and follow
familiar diurnal patterns.

&&

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

&&

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

$$

DISCUSSION...Hodges
AVIATION...Sawtelle/Feldkircher
FIRE WEATHER...Hodges/AJ