{"id":3322,"date":"2026-07-07T17:41:53","date_gmt":"2026-07-07T17:41:53","guid":{"rendered":"https:\/\/discussions.weather.arizona.edu\/?p=3322"},"modified":"2026-07-07T17:42:37","modified_gmt":"2026-07-07T17:42:37","slug":"isolated-mountain-storms-today-for-se-arizona-and-the-mogollon-rim-with-extreme-heat-in-the-valleys-monsoon-is-approaching-though-july-7th-2026","status":"publish","type":"post","link":"https:\/\/discussions.weather.arizona.edu\/?p=3322","title":{"rendered":"Isolated mountain storms today for SE Arizona and the Mogollon Rim with extreme heat in the valleys, monsoon is approaching though!: July 7th, 2026"},"content":{"rendered":"\n

Summary<\/h2>\n\n\n\n

Over the past several days, moisture levels have increased in Arizona, with the 50\u00b0F isodrosotherm moving northward and westward, contributing to thunderstorm development. Weather balloon observations show rising precipitable water, and satellite imagery shows patchy thunderstorm activity, especially in mountainous areas. Widespread storms remain limited due to the lack of organization of monsoon flow. <\/p>\n\n\n\n

Today, isolated storms are expected in the mountains, but most of the low desert will remain dry. Tomorrow, increased moisture and instability will bring more widespread thunderstorms and blowing dust, especially around Tucson, while Maricopa County will likely stay dry. Through Thursday, storms are forecast to form primarily in the mountainous areas in the Tucson area, with outflow boundaries aiding development in the valleys. Dewpoint and precipitation forecasts indicate a continued trend of increasing moisture into the end of the week, with Thursday night into Friday looking more like the meteorological start of the monsoon season. <\/p>\n\n\n\n

Yesterday’s Weather<\/h2>\n\n\n\n

Thunderstorms developed in the White Mountains, much of Graham County, and the western half of New Mexico.\u00a0The\u00a0visible satellite, wind gusts, and\u00a0lightning\u00a0composite show the main areas of activity at 5 pm yesterday. Microbursts were not that strong, generally less than 40 mph, mainly due to low precipitable water values. \u00a0The dry air aloft moving south behind the low-pressure system in Oklahoma resulted in mostly clear skies over the lower elevation; eastern New Mexico and west Texas.<\/p>\n\n\n

\n
\"\"
GOES-19 visible satellite imagery overlaid with maximum wind gusts and GLM lightning flashes from July 6th at 5 pm at the College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n

The upper-level low-pressure system, \u201cL2\u201d, is exiting the region and, except for the dry air over west Texas and eastern New Mexico that limited thunderstorms, it has not been much of a factor. Low \u201cL3\u201d is moving slowly west and has been responsible for the divergence aloft along the Sierra Madre in the area in black. Deep convection has been firing each day in this area, with the strongest storms a couple of hundred miles further north.\u00a0The area marked in green should be the location of strong storms today. Low \u201cL4\u201d is drifting west in the southern part of the Gulf of Mexico, and low \u201cL5\u201d has formed.\u00a0<\/p>\n\n\n

\n
\"\"
GOES-19 upper-level water vapor image from July 7th at 7 am, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n

Analysis<\/h2>\n\n\n\n

Over the past few days, the 50\u00b0F isodrosotherm (line of constant dewpoint temperature) has moved further north and west into Arizona, advancing and retreating each day. This is partly due to mixing from thunderstorms, and the moisture will help initiate thunderstorms again today.\u00a0<\/p>\n\n\n

\n
\"\"
Surface weather station observations for Arizona and New Mexico at 7:00 am, NWS<\/a><\/figcaption><\/figure>\n<\/div>\n\n\n

The observed weather balloon sounding in Phoenix\u00a0at 5 am\u00a0shows an increase in moisture in a layer between 600mb and 480mb;\u00a0the precipitable water increased to 29mm (1.15\u201d ). Winds are southerly below the moisture layer. Given the amount and vertical distribution of moisture, storms can form in the mountains but not in the low deserts.\u00a0The HRRR-UA WRF 12Z initialization matches the observed precipitable water, moisture and wind profile. A touch too much moisture in the boundary layer of the forecast initialization.<\/p>\n\n\n

\n
\"\"
HRRR-UA WRF 12Z (left) initialization and observed sounding (right) at Phoenix for 5 am this morning.<\/figcaption><\/figure>\n<\/div>\n\n\n

At 250 mb, the upper-level lows \u201cL3\u201d and \u201cL5\u201d are just on the edge of the forecast initialization below, along with the monsoon ridge (subtropical high pressure) in the middle. The ridge axis extends northward, then northeastward into Nebraska. \u00a0<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

At 500 mb, the monsoon ridge is just south of the four-corner region, with an upper-level low forming near Eagle Pass, Texas.\u00a0<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

The monsoon flow pattern is getting a little better organized at 700 mb, but still not strong enough today to support widespread storms.<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

Today<\/h2>\n\n\n\n

The forecast sounding for Tucson at 6 pm today is below,\u00a0and there\u2019s barely any Convective Available Potential Energy (CAPE). Any storms forming on the mountains that could produce microbursts won\u2019t be large\u00a0enough to create widespread blowing dust.<\/p>\n\n\n

\n
\"\"
HRRR-UA WRF 12Z forecast sounding at Tucson at 6 pm today.<\/figcaption><\/figure>\n<\/div>\n\n\n

The Nogales forecast sounding for 1:30 pm has more CAPE with storms forming in the early afternoon. \u00a0Wind gusts up to 40 mph are possible with these storms, with some localized blowing dust.\u00a0<\/p>\n\n\n

\n
\"\"
HRRR-UA WRF 12Z forecast sounding at Nogales at 1:30 pm today.<\/figcaption><\/figure>\n<\/div>\n\n\n

The HRRR-UA WRF 12Z forecast radar reflectivity shows that storms form early in Santa Cruz County and move southwest. Convective initiation will\u00a0be later in the afternoon for the Tucson area mountains.\u00a0<\/p>\n\n\n\n