Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/05/20
Area Forecast Discussion
National Weather Service Phoenix AZ
457 PM MST Tue Aug 4 2020
.UPDATE...Updated Aviation Discussion.
&&
.SYNOPSIS...
High pressure will persist across the Desert Southwest
this week resulting in a continuation of above to well above normal
temperatures and dry conditions. Daily high temperatures across the
lower deserts will mostly range from 107 to 112 degrees for most
of the period. Storm chances will generally continue to favor
high terrain areas mainly in far east to southeast Arizona.
&&
.DISCUSSION...
Early afternoon satellite imagery indicated a swath of mid-upper
level Sc-Cu clouds lifting north from Sonora into south-southwest
and S-central AZ with a NW MX-S CA trough disturbance. Radar
indicated a few light to moderate showers with the clouds near the S
AZ-MW MX borderland. The UL high was centered over SW-central NM.
The latest ACARS soundings showed dry westerly and south-
southwesterly flow aloft beginning below 850mb except for a layer of
elevated RH near 550 mb. With mostly clear skies across most of the
region and plenty of heating highs are on their way to top out at
108-112 degrees today around Phoenix and 111-113 out west. This will
be the last day of the Phoenix and S-central AZ excessive heat
warning which will finally expire tonight at 8 PM MST.
The CA dry trough anomaly will expand a bit inland but not move much
for the remainder of the week and bring dry southwesterly flow
across the region with the high remaining to the east over TX and
the W Plains. Modest regional height falls over the next few days
will allow a slight drop in temperatures across the lower deserts
for the rest of the week, however they will remain above normal
and as low as 106-109 by Thursday.
There will also be a drying trend for surface dew points and RH
through the late week. A possible modest spike in PW and CAPE near
Phoenix and E Maricopa county on Thursday is not expected to
significantly improve storm or precipitation chances with PoPs
remaining below 10 percent. Storm chances will generally continue
to favor high terrain areas mainly in far east AZ and southeast
AZ.
For the weekend and early next the high shifts west-southwest
into NW MX and S AZ with anomalously strong H5 heights forecast
for that area. As a result another warm-up is expected during the
weekend and early next week with highs returning to around 109-112
for Phoenix and the lower deserts. The high will also be well
positioned to block any significant moisture for the region.
&&
.AVIATION...Updated at 2355Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Minimal weather impacts should exist through Wednesday afternoon
under mostly clear skies. Typical daytime west winds should with
a few gusts 15-20kt will continue into the early evening. While
any thunderstorm activity will remain well removed from the
terminals, there is a remote chance of a weak boundary and minor
wind shift moving into the metro tonight. Additionally, virga may
be noted due to weak high based showers passing through the area
the next few hours. Aside from this scenario, west winds will
likely linger longer into the overnight with a brief of easterlies
possible.
Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty afternoon and early evening winds will be the primary weather
hazard through Wednesday afternoon under mostly clear skies.
At KIPL breezy westerlies will be the norm this afternoon, with
lighter west to wind overnight. A period of southeast wind will
be possible on Wednesday morning. At KBLH west to southwest wind
will continue with gusts up to 25 kts during the afternoons.
&&
.FIRE WEATHER...
Friday through Tuesday:
A hot and dry weather pattern will continue across Arizona with
relatively dry conditions and above normal temperatures. Wetting
rains are generally not anticipated most days, but the threat of
isolated storms will continue to be possible across far eastern
Arizona. Min RHs will generally fall into the teens each afternoon
with single digit values over portions of the lower western
deserts. Overnight max RH should range around 25-45 percent with
locally higher values possible across southern Gila County. Winds
will be mostly light and diurnal each day, but with some afternoon
breeziness.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST this evening for AZZ534-
537>544-546-548>551-553-554-559.
CA...None.
&&
$$
DISCUSSION...Sawtelle
AVIATION...Hodges/Iniguez/MO
FIRE WEATHER...Sawtelle/Kuhlman