827
FXUS65 KTWC 031726
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
1026 AM 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.

&&

.UPDATE...
We`re starting to see moisture slowly ebb with precipitable water
values ranging from 1.3 to 1.5 inches and surface dewpoints down a
few degrees. Gradual additional drying from the north today. The
12Z KTWC sounding had a little more convective inhibition with a
bit less convective potential. We tweaked the forecast a bit for
slightly better valley support east and south of Tucson, otherwise
current trends for weaker coverage near and north of Tucson. Watch
for a significant drop in dewpoints across Pinal and possibly
eastern Pima county later this afternoon. Also looking 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. Please see the previous discussion below for
additional details.

&&

.PREV DISCUSSION... /issued 302 AM MST Wed Jul 3 2024/

A few light showers were occurring across the area as of 240 am.
Infrared satellite imagery showed plenty of debris cloudiness over
the area along with a MCV south of the New Mexico boot, moving to
the NE. PW value this morning are generally in the 1.3" to 1.6".
These values will gradually decrease today with values down about
a tenth of an inch or two as the flow aloft turns to the N with
high pressure off west coast nosing in. Scattered showers and
storms this afternoon/evening with Intl border locals seeing best
chance of storms. Highs above normal.

Ebb and flow of moisture will keep isolated to scattered storms
around on the 4th and Friday. Again best chances will be near the
Intl border. Highs Thursday similar to today then turning hotter
on Friday. With the heat risk in the major category for the lower
deserts of Pima and Pinal counties, went ahead and hoisted up a
Excessive Heat Watch for Friday. A few places will be near July
5th record highs. See climate section below.

This weekend into next week, hanging on to enough moisture for
continued slight chance PoPs mainly south and east of Tucson.
Turning hotter early next week where heat risk will likely be in
the major category. Later shifts will ponder hoisting Excessive
Heat Watches.

&&

.AVIATION...Valid through 04/12Z.
FEW-SCT clouds (locally BKN) at 9k-12k ft AGL and SCT-BKN clouds AOA
20k ft AGL thru 03/18Z, with ISOLD -SHRA/-TSRA. Between 03/18Z and
04/05Z, 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
thru the remainder of the forecast period. 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

Date                         Jul 05
                          FCST RCD/YR
Tucson Intl Airport       109 111/2018
Organ Pipe Cactus         111 115/1983
Picacho Peak              113 113/2007
Safford Ag Station        108 109/2007

&&

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Friday morning through Friday evening
for AZZ501-502-504-505.

&&

$$



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