Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
795 FXUS65 KTWC 221635 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 935 AM MST Sat Jun 22 2024 .SYNOPSIS...A strong increase in moisture will bring daily chances of thunderstorms to the area into next week. Some storms will generate strong outflow winds with locally heavy rain possible. This will also knock several degrees off of the heat. We may see temperatures climb back up a bit as high pressure settles overhead next week. .UPDATE... The 12Z sounding at KTWC came in signaling lots of moisture in the area with a PWAT of 1.65 inches. Southerly flow suggests moisture will continue to move into the area with PWATS pushing closer to 2 inches into the early afternoon/ evening hours. This morning there is a thick layer of clouds over much of southeastern Arizona with pockets of clear to mostly clear skies in parts of southeastern Pima county, eastern Santa Cruz county, and western Cochise county. With so much cloud cover this will make widespread surface heating difficult suggesting that the areas with more prolonged surface heating will have a higher likelihood to see isolated thunderstorms. Atmospheric instability is not as intense as yesterday with surface CAPE forecast to be around 1000-2000 J/kg and DCAPE around 500-1000 J/kg. Timing of storms will likely begin around noon to 1 PM MST in Santa Cruz and Cochise counties possibly becoming more widespread as the day continues. There is uncertainty on how widespread and how intense the storms will be today. This is due to whether enough widespread surface heating will occur and enhance instability leading to thunderstorm development. If storms are to develop, given the high atmospheric moisture and the slow mean wind aloft, storms will move slowly and be heavy rain producers with strong gusts possible. Thunderstorms will taper off around 9 to 10 PM MST this evening. && .DISCUSSION...Deep monsoon season conditions with unseasonably high moisture levels for late June will continue. Surface dewpoints in the 60s with precipitable water values between 1.3 and 1.7 inches. Additional moisture is pushing up the gulf and western Mexico, with Hermosillo dewpoints jumping 25 degrees into the 60s over the past 24 hours. KYUX vad wind profile showing a solid 15-20kt southerly flow up to 4k ft deep. We`re seeing a lot of light shower activity embedded in debris cloud pushing up from the south this morning. We`ll not be able to match yesterday`s insolation and moisture may actually end up being too high for stronger storms with organized outflows. Perhaps too much of a good thing. Regardless, we once again have Marginal risks from both SPC (for thunderstorm winds) and WPC (for excessive rainfall) for today, and that looks reasonable for now. As central and western areas (generally west of Tucson) continue to see increasing moisture, we`ll actually see some modest drying filtering into eastern areas. We may be down a bit in much of Cochise and Graham counties today after being worked over last night and this morning. Still, ensemble means continue to spread the ridge further west with the high center reconsolidating overhead the first half of the new week. Warmer mid levels and weaker moisture support should start to tamp storm coverage down a bit, but additional surface heating will counter that somewhat. The bottom line is we keep a chance of thunderstorms going well into next week, however we should start to rely more on recirculated boundary layer moisture with the overall trend down. It`s looking more and more as if we will keep enough moisture around to avoid more excessive heat headlines. There`s even a hint that we may see some moisture reinforcement from newly awakened Sinaloa and Sonora later next week. && .AVIATION...Valid through 23/12Z. SCT-BKN clouds 7K-12k ft AGL. SCT -SHRA with ISOLD -TSRA this morning, increasing chances between 22/18Z-23/03Z. TSRA and BKN CIGS around 6k ft AGL possible thru 23/03Z. East to southeast winds 10-15 kts. Stronger and erratic outflows possible with storms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...A strong increase in moisture will bring better RH values along with a chance of thunderstorms into next week. Some storms will generate strong and erratic outflow winds. Moisture is expected to be deep enough for some storms to generate locally heavy rain. Temperatures may heat back up by mid week as high pressure builds nearly overhead, however we should keep some storm chances around. && && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...Malarkey Previous... Meyer Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson