Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
049 FXUS65 KTWC 232023 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 123 PM MST Sun Jun 23 2024 .SYNOPSIS... Ample moisture will bring daily chances for thunderstorms to the area through next week. Locally heavy rain will be likely with any thunderstorm that develops, along with an isolated chance for strong wind gusts. This will also knock several degrees off of the heat. Temperatures may climb up a bit middle of next week as high pressure builds overhead. && .DISCUSSION... The anomalously rich moisture plume remains in place across southern Arizona, currently centered across the southwest with a gradient over southeastern Arizona. GOES precipitable water indicates values from around 1-1.25 inches near the New Mexico border to 1.5-1.7 inches from Tucson-Nogales westward. Combined with widespread surface dew points in the 60s this afternoon, the moisture in place should remain sufficient to produce heavy rainfalls for any convection that develops, especially in areas with greater instability. This instability window should be centered along an axis from the Santa Cruz County area and through central to eastern Pima, as well as part of Cochise county and potentially southern Graham county. This corridor is where the overlap of precipitable water values to the west and easterly mid- level lapse rates (associated with drier air moving in from New Mexico) lies. Instability should remain more limited for now in Pinal County as ongoing cloud cover there has kept temperatures relatively cooler. Thunderstorms are expected to develop this afternoon, with the strongest potential lying in the corridor of best instability where SBCAPE could exceed 2000 J/kg. Heaviest rainfall rates are most likely in this corridor as well, given the moisture in place (as well as isolated severe wind gusts). As convection forms closer to the International Border early this afternoon, outflows should push activity towards the Tucson area as the day goes on. Uncertainty with coverage precluded a watch for flooding today, but messaging the heavy rainfall rate potential is needed as an isolated threat for flash flooding remains. GOES water vapor imagery paints the picture for the coming days as a stream of deep moisture amid easterly flow remains oriented across the southern Gulf of Mexico through northern to central Mexico, with a tropical disturbance moving over into Mexico today. Between the push of Gulf moisture and the aid of the tropical disturbance, the anomalously rich southeastern Arizona moisture should nudge up a notch tomorrow. 12Z HREF ensemble max QPF shows the spatial expansion of potential heavy rain across southeastern Arizona Monday afternoon through the overnight hours. If this trend holds through the upcoming model runs, messaging for Monday may need to be ramped up. Daily convection chances remain in the forecast through the remainder of the week as a mostly persistent pattern aloft keeps moisture in place. A subtle westward nudge of the upper level high may bring mid-level moisture down a touch by the middle of next week, but with ample surface heating expected every afternoon and evening should have at least some sort of convective potential. && .AVIATION...Valid through 25/00Z. Scattered TSRA near KOLS from 24/20Z to 25/01Z, developing near KTUS after 24/22Z. Isolated -SHRA or -TSRA possible elsewhere through 25/03Z. Locally heavy rainfalls with any thunderstorms may significantly reduce visibilities. Overall winds generally remain under 12 kts with occasional gusts to 18Z in the afternoon, while strong gusty outflow winds are possible under any thunderstorms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Unseasonably rich moisture will keep relative humidity values generally on the higher side through this week, along with daily chances for thunderstorms. 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. && $$ Public...Edwards Aviation...Edwards Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson