Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
733 FXUS65 KTWC 241718 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 1018 AM MST Mon Jun 24 2024 .SYNOPSIS... Ample moisture will bring daily chances for thunderstorms to the area into next week. Locally heavy rain will be likely with any thunderstorm that develops, along with an isolated chance for strong wind gusts. Temperatures will heat up a few degrees as high pressure builds overhead. && .UPDATE... Another moist day with the 12Z sounding at KTWC observing 1.84 inches of PWAT. The pattern observed over the weekend persists today with continued southerly flow keeping moisture in the area with afternoon/ evening hour PWATS forecast to be around 2 inches. Higher PWATs of 2 to 2.1 inches will be focused in western Pima county and decrease moving east across SE AZ with PWATS around 1.1 to 1.2 inches in Cochise county. Looking at NEAFS, PWATs are anomalously high pushing into the 99th percentile to maximum climatological values for this time of year. A thick cloud deck this morning is situated over eastern Pima county, Santa Cruz county, eastern Cochise county, and Graham and Greenlee counties. The clouds seem to begin clearing out, though time will tell how well the clouds are able to dissipate. How well clouds clear this morning will increase confidence on how widespread convection will be this afternoon. Instability today will be largely dependent on how well clouds are able to dissipate. If clouds clear, greatest instability appears to be focused in Santa Cruz county with CAPE around 2000-2500 J/kg and more widespread CAPE of 1000-1500 J/kg for the rest of southeastern AZ. DCAPE is fairly weak today with values around 500-1000 J/kg. Isolated to scattered storms are forecast to begin developing around 2 to 3 PM MST, focused to start in and around Santa Cruz county and become more widespread into Pima and Cochise county around 3 to 4 PM MST. This is highly dependent on how well clouds clear and allow for storms to develop. Based on how high atmospheric moisture is and the speed of mean wind aloft, the main concern associated with thunderstorm development is heavy rain with the potential for flash flood conditions and a strong gusty wind or two. && .DISCUSSION...Unseasonably deep moisture for late June remains in place over SE AZ, with surface dewpoints in the 60s and precipitable water values between 1.5 inches east and 1.9 inches west. Another morning with convection hanging on through the overnight hours. Main focus for storms continues to be locally heavy rainfall with localized flooding issues. For today, the deepest moisture axis continues through Santa Cruz county and the T.O. Nation as modest mid level drying tries to mix into eastern areas. We`ll once again have plenty of debris cloud to sort through early with slower insolation in most locations. WPC has us up to a slight risk in the excessive rainfall outlook today, and looks warranted as we continue to manage solid convective potential across most of the area today. Wet microbursts again the main concern, possibly over more of the area than yesterday. High pressure will strengthen over the desert southwest with a new high center consolidating nearly overhead over the next 36 hours. With the depth of the moisture in place we`ll probably only manage 2 to 5 degrees of heating with this. Mid level warming will tend to suppress convection, but we should keep a chance of thunderstorms going even as we slowly mix out some of the moisture over the next few days. Another (weaker) easterly wave will push from Mexico into the Pacific around Wednesday or so. A little further south, but still in a position to push a fresh but likely weaker surge of moisture toward the area later in the week. && .AVIATION...Valid through 25/12Z. SCT-BKN 080-120ft AGL with scattered SHRA and isolated TSRA this morning. Brief MFR conditions possible with storms. Showers will diminish after 24/13Z before chances increase between 24/20Z to 25/03Z. Overall winds generally remain under 12 kts with occasional gusts to 20 kts in the afternoon, while strong gusty outflow winds are possible around any thunderstorms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Relatively deep moisture will keep RH values on the higher side into next week, along with daily chances for thunderstorms. Moisture is expected to be deep enough for some storms to generate locally heavy rain. && && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...Malarkey Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson