Dog days

The National Weather Service says a potentially record-breaking heat wave was rolling through Tucson this weekend, and Green Valley and Sahuarita were likely to feel the burn as well.

In Tucson, the NWS issued an excessive heat warning for the Tucson, Sahuarita and Green Valley area starting Friday at 10 a.m.

At 10 a.m. Saturday, the heat warning extended to the better part of southern and western Arizona, including everything along the Interstate 19 corridor. The heat warning remains in effect until Monday at 8 p.m.

Several Tucson-area heat records are at risk this weekend.

Saturday's 111-degree projection would match the record high set in 1958. Sunday's 114-degree projection not only breaks the daily record of 110 degrees set in 2005, but it also matches the all-time July record high set in 1989 and 1995. Monday's 110-degree projection ties the 110-degree record set in 1994.

The record for consecutive days 110 degrees or higher in July is four days, in 1995. The NWS records for Tucson go back to 1895.

GV records

There are no official records for the Green Valley and Sahuarita areas because no individuals or organizations have volunteered to track temperatures.

NWS meteorologist Emily Carpenter said the closest official record location is Tucson International Airport.

"While we have observations in Green Valley, many of those observations are privately owned weather stations," she said.

Those private observers share the data through outside platforms on the internet, which anyone can access.

Private observers also move in and out of the area, which creates inconsistency. There are also unknowns in their equipment calibration and reliability since the NWS doesn't own private weather stations.

"When we do record keeping, we need equipment that we maintain and we know it's properly calibrated and sighted correctly," Carpenter said. "So we know the data is accurate. And that's just not something we have in place in Green Valley at this time."

The Weather Service does have a Cooperative Observer Program where individuals or organizations can volunteer to take readings and submit them to NWS. In time, the data collected would form official records, which the NWS would have quality control over.

The NWS also covers all the equipment costs and maintenance.

"We need somebody who is going to be consistent in taking observations, who is willing to go through a little training and report the data on a daily basis," she said.

Carpenter said the NWS would like to get one of its stations in Green Valley and Sahuarita but they haven't had any volunteers.

GV and Sahuarita

In the meantime, when it comes to determining record-setting temperatures and events, the local area will have to rely on Tucson.

However, Carpenter said there isn't much difference in the temperature from the airport to Green Valley, typically a couple of degrees.

There is potentially more difference in temperatures within Tucson.

"Even if the Tucson airport gets up to 114 on Sunday, there will be areas in Tucson, there will be other weather stations, there will be localized pockets of temperatures that are higher than that," she said.

In Green Valley and Sahuarita, the weekend's highs aren't too far off from Tucson's potential record-breaking heat.

The NWS forecasted the area would hit 110 degrees on Saturday, 112 degrees on Sunday and 107 on Monday.

 Carpenter said some local circumstances could cause those projections to change.

"If you do have some convection to the south," she said. "We are forecasting isolated showers and thunderstorms, especially across Santa Cruz County. Sometimes, if you get some cloud cover into the Green Valley area, you could have lower temperatures than Tucson if the clouds don't get up north."

And while Green Valley might not be as hot as Tucson, residents should still consider the Tucson high-temperature warnings.

"Anytime you get above 105 when you're looking at 110, and up into the one-teens, it's very extreme," Carpenter said. "And it's not only just vulnerable populations, but it's everybody."

Still hot

The extreme heat warning started Friday and continues through Monday, but it doesn't mean there's significant relief on the way.

"Into the middle of next week, we're looking at between 104 and 106," Carpenter said. "So that's going to be Tuesday, Wednesday, Thursday; that's still several degrees above normal. Tucson normal right now is 101. That's still running 3 to 5 degrees above normal next week."

Here's your silver lining.

Carpenter said Friday and Saturday next week could be closer to the normal 101 degrees.

As for rain, it's still unclear.

"Isn't that everybody's question," she said. "They want to know. The folks want to know."

A better pattern is on the way, bringing more moisture to the area. But the official forecast doesn't show significant chances for showers, though there was a brief downpour on Thursday in Green Valley.

"If anything, it's going to be isolated mainly to the mountains over the next week, but we are seeing signs that the pattern is getting better," Carpenter said. "So I'm hoping, again hope, that in the next week to two weeks, we'll start having more daily chances."

There was 15 percent chance of a shower or thunderstorm in the Green Valley area Saturday.

However, she said the monsoon that started June 15 is still in its early stages, and people shouldn't get discouraged about the little storm activity.

Carpenter said people should give it a few more weeks for any good rainfall chances since the monsoon's busiest time comes at the end of July through August.

But when those chances increase, it's still a dice roll on which areas will get the storms.

"It just depends where you're located," she said. "And as any monsoon goes, you can be a winner or you can be a loser."

Jorge Encinas | 520-547-9732