textproduct: NWS Tucson Arizona

SYNOPSIS

A more quiet monsoon pattern will begin today. Slight chance for isolated showers and storms today mainly south and east of Tucson. Near normal temperatures today with highs in the upper 80s to 90s, gradually increasing over the next 7 to 10 days.

KEY MESSAGES

- Slight chance for isolated showers and storms today mainly south and east of Tucson. Marginal risk for excessive rainfall noted by WPC and general risk for thunderstorms noted by SPC.

- Near normal temperatures today with highs in the upper 80s to 90s, gradually increasing over the next 7 to 10 days.

- Low-grade monsoon pattern returns this weekend.

DISCUSSION

The MCS that lead to widespread rain showers and isolated thundershowers, continues to move westward and is now located over the Tohono O'odham Nation. This system will slowly shift westward reaching Yuma overnight. As of now, the system is bringing light showers to far western Pima county and western Pinal county with a small thundershower forming in the center of the MCS near Sells. There are some isolated weak thunderstorms developing along the Chiricahuas, the Huachucas and slightly stronger in the White Mountains in far northern Graham and Greenlee counties. Storms and showers are expected to stay south and east of Tucson today with a very slight chance for showers to pass through the Tucson area late this afternoon into the early evening hours. The 18Z upper air sounding launched at Tucson shows a fairly saturated atmosphere with PWATs around 1.68 inches. SBCAPE and DCAPE are fairly weak around 500 and 300 respectively. The main concern with storms that develop today will be heavy precipitation and locally gusty winds.

Tomorrow, a low pressure center aloft with move northeastward from off the coast of northern Baja into southern Arizona as high pressure located over central Texas intensifies. This will lead to southerly flow aloft and a weak 45-50 kt jet streak over central Pima county tomorrow afternoon. The low pressure will also push some moisture out of our area sending into into northern Arizona and New Mexico decreasing PWATs to 1.1 to 1.4 inches. The bulk of instability will be focused to areas west of Tucson, leading to a chance for isolated to scattered showers and thunderstorms in the late afternoon to early evening hours. There is a still a chance for isolated showers and thunderstorms to form east of Tucson.

Towards the end of the week into the weekend, the low pressure center aloft will weaken and push northward into central California. The high pressure over central Texas will continue to intensify shifting wind directions to the southwest in southern Arizona. This upcoming pattern is not the most favorable for thunderstorm development, thus low-grade monsoon will begin as early as Friday. Daytime high temperatures will gradually increase to near or slightly above normal temperatures over the next 7 to 10 days. The CPC 8-14 day outlook shows a 40 to 60 percent probability for leaning above normal temperatures and a 33 to 40 percent chance for leaning below normal precipitation.

FIRE WEATHER

Temperatures will be slightly cooler than normal today and Thursday, then near normal late this week. Deep moisture in the area today will move northward tomorrow, decreasing moisture over the weekend into early next week. Afternoon winds will remain westerly from 10-15 mph, with occasional gusts at or above 25 mph. Afternoon RH values in the low lying areas will be 20-30% through Friday decreasing to 17-25% over the weekend.

TWC WATCHES/WARNINGS/ADVISORIES

None.