Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
353 FXUS65 KTWC 120850 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 150 AM MST Wed Jun 12 2024 .SYNOPSIS...Excessive heat continues through Thursday as high pressure results in very hot temperatures. Slight cooling Friday but temperatures still a few degrees above normal. Temperatures then nudge upward again this weekend into early next week. Generally dry conditions through the forecast period with a slight chance of mainly dry thunderstorms in the eastern mountains late Thursday into Friday. && .DISCUSSION...The main forecast concern in the short term will continue to be the heat. An Excessive Heat Warning remains in effect for lower elevations through Thursday. The ridge of high pressure aloft will be peaking in strength today through Thursday as its located near the AZ/NM border. Tucson will be right on the cusp of 110 degrees for high temperatures both today and Thursday. NBM probabilities are right around 20 percent for 110 or greater both days. If Tucson hits 110 it would be a couple of weeks earlier than the long term average of June 28th since 1895. As a mid/upper low off the CA/northern Baja coast ejects to the east near San Diego Thursday evening and then into AZ Friday, that will set the stage for some increased breeziness Thursday with locally elevated fire weather conditions. In addition, a bit of mid level moisture is expected in the southerly flow ahead of the low, so there will be a few more cloud build-ups Thursday with a slight chance of a sprinkle/light shower or dry thunderstorm Thursday night into Friday across the higher terrain of Graham and Greenlee Counties. The gradient will tighten a bit more on Friday as the low ejects east and opens up into an open wave. The uptick in winds Friday for locales east of Tucson is enough to result in areas of critical fire weather and therefore a Fire Weather Watch remains in effect for much of southern Greenlee/SE Graham and eastern Cochise Counties. Meanwhile, as heights/thicknesses drop slightly, temperatures will back off a few degrees compared to today and Thursday. For this weekend, ensembles are showing broad ridging building back in to our south with SE Arizona on the north side of this ridge under westerly flow aloft. This will result in dry conditions with temperatures nudging up again this weekend. We`ll continue to monitor for the need of additional heat headlines but given that we`re getting later into June when it`s climatologically a bit hotter, it takes a bit more to see widespread major heat risk. At this time, heat risk for the weekend is mostly in the moderate category with a couple localized spots at the major levels. For early to mid next week, our area will generally be in southwesterly flow aloft between broad troughing to our north and west and the subtropical high to our south and east. Ensembles are showing a dry forecast for us as moisture is well to our south and east. However, some hints that the high could shift a bit more northward in the 8 to 10 day period which could open the door for a bit more mid level moisture increase. One step at a time as Monsoon 2024 gets underway after the official June 15 start. && .AVIATION...Valid through 14/12Z. SKC thru 13/18Z then FEW-SCT clouds 12-16k ft AGL through the end of the forecast period. SFC winds generally less than 12 kts this morning, then WLY/NWLY at 10- 15 kts aft 13/20Z with gusts around 20 kts. Winds then diminish to generally less than 12 kts aft 14/03Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Hot temperatures this week, with high temperatures 7-10 degrees above normal through Thursday and then 3-6 degrees above normal Friday through the weekend. Limited mid-level moisture will result in a slight chance of mainly dry thunderstorms in the higher terrain northeast of Tucson late Thursday and Friday. These storms may produce gusty and erratic winds, along with occasional lightning. Expect min RH values of 3-9 percent in the lower elevations and 7-15 percent in the mountains through this weekend, along with poor overnight recoveries between 20-35 percent in most locations. Outside of any thunderstorm outflows, 20-foot winds will follow typical diurnal patterns, with afternoon/early evening gustiness due to strong surface heating. Sustained 20-foot wind speeds will generally be 15 mph or less today, increasing to around 15 mph Thursday. Thereafter, elevated winds at 15-22 mph and gusts to around 35-40 mph along the Arizona/New Mexico border Friday. This will result in critical fire weather conditions. Therefore, A Fire Weather Watch is in effect Friday for Fire Weather Zone 152 (including Cochise, Graham and Greenlee counties). Afternoon breezes continue this weekend but below critical levels. && .TWC WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM MST Thursday for AZZ501>509. Fire Weather Watch from Friday morning through Friday evening for AZZ152. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson