Forecast Discussion

Forecast Discussion for TWC NWS Office
000
FXUS65 KTWC 162030
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
128 PM MST Tue Aug 16 2022

.SYNOPSIS...Shower and thunderstorm chances will continue. A slight
downward trend in storm activity is expected this evening before
ramping back up the second half of the week into the weekend.
Temperatures will remain near seasonal averages through Wednesday,
lowering to nearly 10 degrees below normal this weekend.

&&

.DISCUSSION...A wetter period can be anticipated starting tomorrow
through the weekend as a low pressure system with tropical origin
impacts the region. This system was centered just south of the Texas
Big Bend today and will track farther westward the next few days.
Models were in good agreement with this low bringing an influx of
deep moisture into the region as it moves closer and becomes
somewhat stalled over NW Mexico/NRN Gulf of California this weekend.
Needless to say, rain chances and rainfall amounts will be on the
increase as early as tomorrow but more so Friday into the weekend.
ECMWF was noticeably wetter than the GFS with the ECMWF ensemble QPF
derived Extreme Forecast Index (EFI) highlighting Saturday for more
widespread heavy rainfall amounts. This scenario would suggest a
transition from a localized flash flooding threat to a more longer
term flooding concern by early next week, if not sooner. Please
refer to the hydrology section in this product for more details.
Otherwise, high temperatures will hover below seasonable readings,
especially Friday into the weekend.

&&

.AVIATION...Valid through 18/00Z.
SCT-BKN clouds 7k-12k ft AGL. ISOLD-SCT SHRA/TSRA developing and
persisting thru 17/04Z mainly from Tucson south and westward. With
the stronger TSRA, expect cloud decks to lower to 4k-6k ft AGL, wind
gusts to 45+ kts, vsby reductions, and mountain obscurations.
Outside of any TSRA, SFC wind generally less than 10 kts and
favoring a NWLY direction through the early evening hours and
variable in direction at other times. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Expect a daily chance of showers and thunderstorms
through the upcoming weekend, with increasing precipitation chances
late in the week into the weekend. The main threats will be strong
gusty winds and heavy rainfall/flash flooding. There is the
potential for precipitation outside the normal afternoon/evening
cycles. Outside of thunderstorm outflows, wind trends will be light
and follow typical diurnal patterns.

&&

.HYDROLOGY...A low pressure system with tropical origin was centered
just south of the Texas Big Bend area today. This low will track
westward bringing an influx of deep moisture to the region as early
as Wednesday but more so this weekend. Latest models showed this low
pressure system becoming somewhat stalled south of the International
Border over Northwest Mexico/northern Gulf of California through the
weekend. As this system moves closer, rain chances and rainfall
amounts will be on the increase areawide, peaking late Friday and
Saturday. While flash flooding will be a concern, mainstem rivers
and larger washes will likely experience significant flows by
Monday, if not sooner. The river forecast outlook, based on the
latest QPF, indicated a few river systems of concern such as the
Gila River upstream from the San Carlos Reservoir. That said,
conditions may transition from localized flash flooding to longer
term flooding concerns.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

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NWS TWC Office Area Forecast Discussion