111
FXUS65 KTWC 072118
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
218 PM MST Fri Jun 7 2024

.SYNOPSIS...High pressure will bring hot temperatures today and
then a few degrees above normal through the weekend. An Excessive
Heat Warning is in effect for today. A weather system will bring
a modest moisture increase today into the weekend, with a chance
of thunderstorms each afternoon mainly near the eastern mountains.
Rainfall should be limited, with strong and erratic winds being
the main threat along with lightning.

&&

.DISCUSSION...Visible satellite imagery this afternoon showed
partly to locally mostly cloudy conditions east of Kearny to San
Sasabe line while water vapor imagery showed upper low off the
srn Baja coast. Radar showing mostly less than 30dbz echoes east
of the above mentioned line with areas of virga east of the above
line with any lighting this afternoon being confined to NE AZ/wrn
NM. Excessive Heat warning currently in effect until 8 pm this
evening. A mixed bag in the afternoon temperatures, as of 2 pm,
with most areas 1-4 degrees warmer than yesterday while a few
areas, especially across Cochise county, where this is more cloud
cover, were running 2 to 4 degrees cooler than yesterday. At 1:59
pm, Tucson airport tied the daily record high of 109 degrees
previously set in 1985. Still time in the afternoon for Tucson
hitting 110 for the first time this year. See climate section
below for additional details.

This weekend will be cooler then Thu/Fri thanks to lower
low-level thickness values as the Baja upper low slowly moves
toward the area. Most recent NBM has around 15% chance Sun that
Tucson may not hit triple-digits. Still enough mid-level moisture
around for a slight chance, less than 20%, of high-based storms
near the AZ/NM border with little rain making it to the ground.

Monday is a transition day with near normal high temperature as
another low sets shop off srn CA/nrn Baja coast with upper ridge
building over AZ/NM.

Tuesday through Thursday: All signs point to another period of
excessive heat, near record highs with possible major heat
related impacts during this period with an upper low off srn
CA/nrn Baja coast and strong upper ridge over AZ/NM. Latest NBM
has come in hotter 1-2 degrees for Tue, 2-3 degrees for Wed and
3-5 degrees for Thursday. This is in line with 30%-40% of the
EPS members for both Wed and Thu having Tucson in the 110-112
degree range. EPS has much of the lower deserts with 10%-50%
chance of exceeding 110 degrees Wed/Thu. Similar to current
scenario, there will be a modest push of moisture from the south
that may lead to high-based, mostly dry, storms.

&&

.AVIATION...Valid through 09/00Z.
FEW-SCT clouds (locally BKN) at 10k-14k ft AGL and SCT-BKN clouds
AOA 20K ft AGL thru the forecast period. There will be a slight
chance of -SHRA/-TSRA mainly east of a KALK to KE77 line thru 08/03Z
and again aft 08/17Z. SFC wind SLY/SWLY at 10-15 kts, with gusts to
18-25 kts thru 08/02Z, then SFC wind less than 10 kts and variable
in direction between 08/02Z and 08/17Z. Aft 08/17Z, SLY/SWLY SFC
wind at 12-17 kts and gusts to 20-28 kts. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Mid level moisture in place will bring a slight
chance of mainly dry thunderstorms east of Tucson through the
weekend. These storms will generally be dry and can produce gusty
and erratic winds along with lightning. Hot temperatures continue
today, with high temperatures 2-4 degrees above normal into early
next week. Expect min RH values of 4-9 percent in the lower
elevations and 8-15 percent in the mountains through the middle of
next week, along with poor overnight recoveries between 20-35
percent in most locations. Outside of any thunderstorm outflows, 20-
foot winds will follow typical diurnal patterns into the middle of
next week, with afternoon/early evening gustiness due to strong
surface heating. Sustained 20-foot wind speeds will generally be 15
mph or less, except for some elevated winds at 15-20 mph and gusts
to around 30 mph Saturday and Sunday afternoon/early evening to the
southeast of Tucson.

&&

.CLIMATE...Here are the 5 earliest calendar dates for the first
110+ degree high for Tucson:

May 29, 1910
June 4, 1990
June 4, 2016
June 8, 1985
June 11, 1933

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Excessive Heat Warning until 8 PM MST this evening for
  AZZ501>509.

&&

$$

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