679
FXUS65 KTWC 032029
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
129 PM MST Wed Jul 3 2024

.SYNOPSIS...Chances of showers and thunderstorms today then
gradually diminishing during the rest of the week. Some storms
will generate strong winds and locally heavy rainfall. With high
pressure building in from the northwest, daytime temperatures will
be trending hotter Friday into at least early next week.
Temperatures are expected to approach record levels in some
locations.

&&

.DISCUSSION...We`re starting to see moisture slowly ebb with
precipitable water values ranging from 1.3 to 1.5 inches. Surface
dewpoints down 4 or 5 degrees with some locations mixing out into
the 50s. Additional drying is expected from the north, with the
exception of western AZ where we`re seeing another surge through
Yuma. Dewpoints in Yuma are up 10-12 degrees into the middle 60s
with the KYUX vad wind profile suggesting the surge is around 5k
ft deep. Some of this will mix into the drier flow as it
circulates through the lower deserts, but in general probably
won`t be enough to keep storms going north and west of Tucson over
the next few days. Still watching for a late afternoon convective
complex near the border but with the flow reversal underway the
orientation of the strongest outflow may not help us much.

By tomorrow afternoon any significant storm chances should be
south of Tucson, with a sharply increasing moisture gradient into
northern Sonora. Strong high pressure will build into the desert
southwest from the west coast, resulting in an unfavorable pattern
for moisture along with hotter temperatures. Moisture trends will
definitely be down as a drier northwesterly flow begins to push
the deepest moisture southward, but probably won`t be strong
enough to completely scour out the moisture as we hang on to at
least border storms.

With that in mind, expect near record heat from Tucson into the
lower deserts Friday and Saturday even as we continue to see some
convection south and southeast of Tucson. We may end up extending
that to include Monday and/or Tuesday, but with questions about
moisture depth and northward extent we`re taking a wait and see
attitude for now.

Ensemble means suggest the high center will eventually
reconsolidate into a more favorable position by the middle of next
week into the following weekend. Keeping an eye on the tropics as
we see an area of interest for tropical storm formation off the
southwest Mexican coast. Also, negative height anomalies suggest
additional easterly wave activity later next week.

&&

.AVIATION...Valid through 05/00Z.
SCT-BKN clouds at 7k-10k ft AGL and ISOLD-SCT TSRA/SHRA. MVFR
conditions near TSRA, with mountain obscurations, VSBY
restrictions and gusts to 40+ knots. Aft 04/05Z, gradual clearing
with ISOLD TSRA possible again after 04/20Z. Outside of TSRA
outflows, SFC wind generally 12 kts or less favoring a WLY/NWLY
direction during the afternoon/early evening hours and variable in
direction at other times. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...There will be the daily chance for isolated to
scattered showers and thunderstorms mainly from Tucson east and
south. High pressure aloft will build to our northwest late this
week into early next week, which will result in hot conditions. With
the hotter temperatures and some of the deeper moisture getting
pushed to the south and east of the region, min RH values will lower
into the 10-18% range across the lower elevations and 15-30% in the
higher elevations Friday into early next week. High temperature will
warm considerably late this week through the weekend, with highs 106-
113 degrees from Tucson westward and in the Gila River Valley, and
in the upper 90s to 105 degrees across Santa Cruz and Cochise
counties. Excessive Heat will likely be an issue during this time
frame. Outside of any thunderstorm outflow winds, 20-foot winds will
generally be 15 mph or less each afternoon with occasional gusts to
20-25 mph through the weekend. Early next week there will be the
potential for more elevated wind speeds in the 15-20 mph range,
especially east of Tucson.

&&

.CLIMATE...

Record or near record high temperatures Friday and Saturday

Date                         Jul 05           Jul 06
                          FCST RCD/YR      FCST RCD/YR
Tucson Intl Airport       109 111/2018     109 110/2023
Organ Pipe Cactus         112 115/1983     111 113/2018
Picacho Peak              113 113/2007     112 113/2005
Safford Ag Station        107 109/2007     106 109/2023
Ajo                       113 117/2007     113 117/2007

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 11 AM Friday to 8 PM MST Saturday
for AZZ501-502-504-505.

&&

$$

Meyer

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