Forecast Discussion
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. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
NWS TWC Office Area Forecast Discussion