Area Forecast Discussion

SYNOPSIS

High temperatures will remain near to slightly above normal through the the weekend and next week. Breezy conditions are expected each afternoon, especially today in the Gila River Valley and Safford.

DISCUSSION

The upper pattern today is defined by an upper- low centered near north Texas, a strong and deep trough of low pressure moving into the Pacific Northwest and a shortwave ridge squeezing in-between these two features across Southeast Arizona. Dry airmass re-establishing itself across the area with GOES precipitable water imagery indicating PWAT values between 0.45-0.55 inches. Tight gradient still residing NE of the 700mb mid-level high (centered just south of the upper ridge axis across NE Sonora Mexico) will result in some breezy northwest winds across the Gila River Valley today. In fact, these winds may result in brief near critical fire weather conditions. However, with the mid-level high moving ESE, I would expect this gradient to continue to relax late this afternoon and this evening.

As we move into the first half of the week, the trough in the Pacific Northwest becomes more established, with a larger scale mean trough developing across the Great Basin into the Desert Southwest...with a trough axis down toward the Baja Spur by 09/00Z Monday afternoon. Although some mid-level moisture will get pushed northward into the far SE corner of state, this system will likely remain dry for our neck of the woods. It will however increase the southwesterly flow across the area, with SSW 700-500 mb winds 35-40 kts across the western half of our forecast area Monday night and Tuesday. We may see some of these winds mix down more so than models forecast resulting in the potential for critical fire weather conditions Tuesday. However my confidence is still low with the timing and strength of the trough axis, and it would be too iffy for any fire weather headlines at this time.

In any event, if you stand on your tippy-toes, you can almost see the Monsoon pattern trying to take shape the second half of the week into next weekend as the trough in the northern stream moves north. The allows for the subtropical high in SRN TX Tuesday afternoon to move west across NRN Mexico to the SRN border of Sonora/Chihuahua Mexico by 13/00Z Friday afternoon. The 06/00Z NBM Grand Ensemble then brings the 1.00 inch PWAT line northward through northern into the western Pima county Saturday. Although there is a large variance, this is supported by the 06/14Z NBM with a 10-25 percent probability of dewpoints 55+ degrees at the Tucson International Airport (KTUS) starting Friday June 12th. I guess its about that time, as the start of the Monsoon season is June 15th.

AVIATION

Valid through 08/00Z. Mainly SKC with some cirrus AOA 20k feet AGL moving in from the west after 07/00Z this afternoon and persisting thru the forecast period. FEW-SCT 10-14k feet AGL clouds will develop east of a KALK-KSAD line aft 07/20Z Sunday afternoon. Surface winds northwest 10-15 kts with gusts to 20 kts from KTUS-KOLS eastward diminishing after 07/03Z this evening to terrain driven less than 10 kts overnight. Stronger winds at KSAD with 17-20 kt winds and gusts to 30 kts. Aviation discussion not updated for TAF amendments.

FIRE WEATHER

Breezy northwest winds 10-15 mph with gusts to 20-25 mph are expected again today from a Tucson-Nogales line eastward. Stronger winds through the Gila River Valley of 18-24 mph and gusts to 35 mph. Minimum relative humidity values will be 8-14 percent across desert locations, which will bring periods of locally critical fire weather conditions in the Gila River Valley with the stronger winds this afternoon. Winds west of Tucson-Nogales will turn to the southwest. Sunday onwards will see southwest winds of 12-18 mph and gusts to 25-30 mph across southeastern Arizona each afternoon. Minimum relative humidity values should remain fairly consistently 8-15 percent across desert locations and 12-18 percent in the mountains through the middle of the week, with the potential for increasing relative humidity Friday into next weekend.

TWC WATCHES / WARNINGS / ADVISORIES

None.