Tucson, AZ 85754 Weather

Synopsis

Temperatures at or slightly above normal today through Thursday, then cooler than normal Friday into the upcoming weekend. An unsettled weather pattern will be around this week with daily chances of shower and thunderstorms with Wednesday afternoon through Thursday having the best chances area wide.

Discussion

An active mid to late October weather pattern for our region this week as our area is influenced by moist south to southwesterly flow. A shearing out trough currently resides within this flow across Arizona with another disturbance tailing back into the northern Gulf of California. We continue to see isolated to scattered showers with some embedded thunderstorms north of Tucson at this time with more development expected from Tucson south and eastward over the next couple of hours. Visible satellite imagery shows an agitated cumulus field developing from Tucson south and east with SPC RAP mesoanalysis indicating around 500-1000 J/KG of MLCAPE. Given the adequate solar insolation today and convective temperatures being reached, scattered showers and thunderstorms are expected through the afternoon from Tucson eastward. A few of these that produce more robust updrafts could be marginally severe for strong wind gusts and hail. The SPC has placed locales from Tucson eastward in a marginal risk for severe thunderstorms. Given the quick movement around 30 mph from these storms, rainfall amounts will generally be 0.2"-0.6" within shower and thunderstorm activity, though any localized locales that see multiple rounds/backbuilding of storms could receive in excess of 1 inch of rain. The WPC also has our area in a marginal risk today for excessive rainfall. After sunset, shower and thunderstorm activity is expected to wane with the loss of daytime heating, though can't rule out some isolated shower activity overnight mainly near the NM border.

The next weather system to impact our area will be an upper low and longwave trough which will be located off the California coast Tuesday. This system will move onshore Wednesday night into Thursday, then northeast into the Great Basin Friday. With the abnormally moist southerly flow continuing Tuesday, isolated to widely scattered showers with a slight chance of a thunderstorm mainly from Tucson north and eastward is expected. Coverage will be less than today given the lack of forcing and dynamics.

The most active period will be Wednesday into Thursday as our area gets more under the influence of the trough and its associated lift and dynamics. The chances of showers and thunderstorms (30 to 80 percent) ramps up Wednesday afternoon especially north of Tucson and continues through Wednesday night and Thursday with the exact end timing dependent on how fast the trough axis moves east. It's early but the convective parameters are certainly favorable for a few stronger thunderstorms as this system moves through, especially if there are enough breaks in the cloud cover for greater instability. The SPC has already placed our area in a Day 3 marginal risk Wednesday. WPC has locales north of Tucson in a slight risk for excessive rain on Thursday, with other locales in a marginal risk Thursday. For Wednesday, most of southeast Arizona is in a marginal risk for excessive rainfall. QPF Wednesday through Thursday is expected to be 0.25" to 0.75" for many locales with localized spots such as the mountains (upslope favored) and northern Graham/Greenlee Counties as high as 1 to 1.5 inches.

Drier air moves in for Friday, though some lingering showers possible near the NM border, which could linger into the weekend as well.

Temperatures through Thursday will be at or slightly above normal, then cooler than normal Friday into the upcoming weekend.

Aviation

Valid thru 21/00Z. SCT-BKN 8k-10k ft AGL. SCT -SHRA/-TSRA thru 20/04z mainly from KTUS eastward. Thereafter, slight chc of -SHRA overnight thru 20/19Z mainly near the NM border. Another round of ISOLD -SHRA/-TSRA mainly NE of KTUS from 20/19Z thru end of valid period. SFC winds ELY/SELY at 5-15 kts with gusty winds psbl near -TSRA. SFC winds become Aviation discussion not updated for TAF amendments.

Fire Weather

Temperatures at or slightly above normal through Thursday, then cooler than normal Friday into the upcoming weekend. Wind speeds mostly less than 15 mph this week except for Thursday with southwest winds around 15 to 20 mph. Minimum relative humidity remains above 25-40 percent through most of the week with most days seeing anywhere from a 20-80 percent chance of showers with embedded thunderstorms at times as an unsettled pattern continues.