139
FXUS65 KTWC 120945
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
245 AM MST Fri Jul 12 2024

.SYNOPSIS...Excessive heat continues across parts of southeast
Arizona today with temperatures then moderating over the weekend
into next week. Today and Saturday storms will mainly be confined
to the White Mountains and central/western Pima County. Sunday
into next week storm coverage will increase to cover most of
southeast Arizona with typical monsoon threats.

&&

.DISCUSSION...Satellite shows left over debris clouds slowly
dissipating across the CWA. Skies should be mostly clear by the
morning. High pressure is centered over the southern Great Basin
and will slowly move towards the Four Corners over the next couple
of days. Water vapor shows drier air moving in to the eastern
portion of the CWA with surface dew points expected to drop into
the upper 40s east of Tucson. Because of this today`s convection
will not be as widespread as Thursday`s. However hi-res models do
show a modest gulf surge moving into western Pima County this
afternoon. This area will be the main focus for storms today as
well as the White Mountains. Storms in western/central Pima County
will be capable of strong winds with the 7/12 00Z HREF showing
50-70 percent chance for winds greater than 30 kts and 10 percent
chance for winds greater than 50 kts within 25 km of a point.
Tucson looks to be on the outside looking in storm-wise with high
temperatures again reaching excessive heat levels. Because of
this an Excessive Heat Warning has been issued today for the
Tucson metro and southeast Pinal County.

Saturday looks to be fairly similar to today with another gulf
moisture surge into western Pima County and drier air remaining in
place from Tucson eastward. Best chances for storms again look to
be western Pima County and the White Mountains with the main
threats being strong winds and locally heavy rainfall.
Temperatures decrease a few degrees as the high becomes centered
over the Four Corners. They won`t be in excessive heat category
but will still be above normal.

Sunday into Monday the high remains over the Four Corners region
and moisture begins to increase. Mean ensemble PWAT values range
from 1.1" along the AZ/NM border to 1.6" in central/western Pima
County. This will likely lead to an uptick in storm coverage
beginning Sunday and continuing into early next week. Strong winds
will be a concern along with the potential of heavy rain and
areas of flash flooding, especially along the international
border. With added moisture temperatures will moderate becoming
around normal Sunday into the middle of next week.

&&

.AVIATION...Valid through 13/12Z.
SCT-BKN clouds at 14k ft AGL through the early morning then brief
clearing until the afternoon. In the afternoon and evening expect
SCT-BKN clouds 8k-12k ft AGL. Isold -TSRA/-SHRA will be possible
in central/western Pima County as the White Mountains, but are not
expected to impact any terminals. Sfc winds will be
easterly/southeasterly 6-12 kts with occasional afternoon gusts to
20 kts. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Today and Saturday best chances for storms will
be in central/western Pima County and the White Mountains with
the main threats being strong winds and locally heavy rainfall.
Moisture increase Sunday into next week leading to an expected
increase in storm coverage and heavier rainfall. Minimum relative
humidities this afternoon and tomorrow will range from 12 to 20
percent in the lower elevations and 15 to 30 percent in mountain
areas. Humidity values increase Sunday into next week as greater
moisture returns. Away from thunderstorms, expect 20 foot wind
speeds of 10 to 15 mph with gusts to around 20 mph each day with
light winds overnight. Wind directions will be easterly today and
Saturday then becoming diurnally terrain driven thereafter.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 11 AM this morning to 8 PM MST this
evening for AZZ504>506.

&&

$$

Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson