068
FXUS65 KTWC 020928
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
228 AM MST Sun Jun 2 2024

.SYNOPSIS...

Temperatures will remain a bit above normal through early this
coming week, with hotter temperatures likely by Thursday. Sunny
skies and afternoon breeziness can be expected over the next few
days.

&&

.DISCUSSION...

Weak and dry troughing will develop across Arizona today with
shallow height falls while an associated modest speed max crosses
northern Mexico. The main impact of this feature will be to bring
an afternoon southwesterly breeze and a few high clouds to
southern areas. High temperatures will remain above just above
normal, though a couple degrees down from yesterday thanks to this
passing trough. High temperatures through Tuesday will likely
remain consistent under the persistent flow pattern aloft.

From Wednesday through the remainder of the work week, a mid to
upper level ridge is expected to set up across the western CONUS.
Height anomalies will become particularly stronger on Thursday,
setting up potentially the first excessive heat day of the season.
Tagging along with the upper ridge is a closed low, forecast to
sit under the ridge just off the western Baja coast by Wednesday
before eventually merging with the mean flow by sometime this
weekend. Ensemble 500mb solutions remain in good consistency in
keeping this low south of the forecast area through Thursday,
which leads to increased confidence in the Thursday excessive heat
potential. As such, an Excessive Heat Watch has been issued for
Thursday across the lower elevations of southeastern Arizona.
High temperatures may also tease excessive heat criteria Wednesday
and Friday, though with less certainty as first the ridge will
still be building on Wednesday and then the potential for the
closed low to meander northeast into southern Arizona on Friday.
Speaking of this low`s progression into Arizona, 00Z and 18Z
ensemble runs have brought a slightly deeper trend, which is in
turn producing an uptick in model QPF. This is especially true
from the GEFS-CMC ensemble precipitation probabilities Friday and
Saturday afternoons. That said, it is not a very notable amount
of precipitation as it only takes the forecast rain into the
measurable tier and not much further. Additionally, the ECMWF
remains on the drier side and with a closed low under a dry ridge,
a drier solution seems more reasonable anyway. NBM precipitation
probabilities have come up with slight to chance values east of
Tucson-Nogales through the New Mexico border, but the likelihood
of these areas seeing more than a few hundredths remains very low.
The more likely scenario should be very dry sub-cloud layers
under dry thunderstorms producing gusty winds and lightning Friday
and Saturday afternoon- evenings.

&&

.AVIATION...

Winds will become southwesterly after 17Z and increase to 13 to 18
kts with gusts to 30 kts, before gradually diminishing after 01Z.
Otherwise mostly SKC with a few high clouds. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...

Dry conditions and high temperatures 2 to 5 degrees
above normal will continue through next Wednesday, becoming 5 to 8
degrees above normal the second half of next week. Minimum
relative humidity values of 5 to 10 percent in the lower elevations
and 8 to 15 percent in the mountains through the middle of next
week, along with poor overnight recoveries between 20 to 30
percent in most locations. Afternoon winds should be breezy,
especially today and Monday with 15 to 20 mph winds and gusts to
around 30 mph (more likely south to southeast of Tucson). Chances
for dry thunderstorms with gusty outflow winds arrive Friday and
Saturday, generally more likely in eastern areas.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Thursday morning through Thursday
evening for AZZ501>509.

&&

$$

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