{"id":2644,"date":"2025-09-11T18:07:26","date_gmt":"2025-09-11T18:07:26","guid":{"rendered":"https:\/\/discussions.weather.arizona.edu\/?p=2644"},"modified":"2025-09-11T18:07:26","modified_gmt":"2025-09-11T18:07:26","slug":"a-similar-set-up-as-yesterday-for-southeast-arizona-with-slightly-better-chances-of-storms-coming-from-the-south-into-the-tucson-metro-area-september-11th-2025","status":"publish","type":"post","link":"https:\/\/discussions.weather.arizona.edu\/?p=2644","title":{"rendered":"A similar set up as yesterday for Southeast Arizona, with slightly better chances of storms coming from the south into the Tucson metro area: September 11th, 2025"},"content":{"rendered":"\n

Yesterday’s Weather<\/h2>\n\n\n\n

Yesterday, storms formed in the mountains mainly along the moisture axis, annotated in orange, from northern Sonora through southeast Arizona then into northern New Mexico. Strong winds aloft blew the tops off the storms eastward making it appear there was more areal coverage than there actually was. The lightning data supports this interpretation with strikes mainly on the west side of the cirrus anvils. <\/p>\n\n\n\n

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GOES19 visible satellite images from September 10th from 3:45pm, College of DuPage<\/figcaption><\/figure>\n\n\n\n

The HRRR-UA WRF 12Z forecast (left) captured the precipitation features well, although a little too heavy with precipitation in eastern Pinal County. 24-hour accumulated precipitation observations from MRMS are on the right. <\/p>\n\n\n\n

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HRRR-UA WRF 12Z 24-hour precipitation accumulation forecast from yesterday (left) versus observed 24-hour precipitation accumulation from MRMS multi-sensor data (right).<\/figcaption><\/figure>\n\n\n\n

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

More moisture is in southern Arizona with 60\u00b0F dewpoint temperatures returning in Pima, Pinal, and Santa Cruz counties. Yesterday, storms that formed entrained the dry lower dewpoint temperature air from the lower deserts, restricting them from moving into the valleys. Today that problem does not appear to exist.<\/p>\n\n\n\n

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Surface weather station observations for Arizona and New Mexico at 10am, NWS<\/a><\/figcaption><\/figure>\n\n\n\n

The observed sounding from Phoenix at 5am is missing today, and the Tucson sounding will not be launched until later this morning. The Guaymas, Mexico sounding is available and had a little over 2 inches of precipitable water compared to less than an inch in the HRRR-UA WRF 12Z initialization for Phoenix below. It\u2019s difficult to understand the upper air situation in the region with this data.<\/p>\n\n\n\n

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HRRR-UA WRF 12Z initialization for 5am this morning at Phoenix.<\/figcaption><\/figure>\n\n\n\n

At 250mb, the low-pressure trough has moved into northwest Nevada with the high-pressure ridge remaining in west central Mexico. Southwest flow continues across the region with windspeeds around 40knots in southeast New Mexico increasing to 85knots in northwest Arizona. Maximun winds in the jet stream over southern Nevada is 105 knots.\u00a0<\/p>\n\n\n

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The overall wind speed has increased 5 to 10 knots in the region at 500mb, although the wind direction remains the same. The ridge and trough have moved eastward with the ridge near yesterday’s forecast position near Abilene, Texas.<\/p>\n\n\n

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At 700mb, the moisture axis may be a little farther west than shown below but overall, the model initialization looks good. Moisture increases during the day with the development of storms. \u00a0<\/p>\n\n\n

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This morning’s GOES-19 visible satellite picture shows scattered clouds moving northward. Of note are the clouds along the east coast of the Gulf of California extending northward to Gila Bend, indicating moisture advecting into the area that\u2019s not in the model forecast.<\/p>\n\n\n\n

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GOES19 visible satellite image from September 11th at 9am, College of DuPage<\/figcaption><\/figure>\n\n\n\n

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

The HRRR-UA WRF 12Z forecast sounding\u00a0for Phoenix at 4:30pm (left) and Tucson\u00a0at 3pm (right), like yesterday, show no Convective Inhibition (CIN) and plenty of Convective Available Potential Energy (CAPE) for storms to develop this afternoon and evening. The limiting factor for Phoenix is the wind direction is not favorable for the metro area but should be good for the mountains to the east and north. Tucson has a little bit of a cap (inversion) near 500mb with an extra 6mm of precipitable water compared to Phoenix. Mid-level winds are southerly meaning for storms to reach Tucson metro they need to form on terrain to our south, the Santa Rita\u2019s, and move north. \u00a0<\/p>\n\n\n\n

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HRRR-UA WRF 12Z forecast sounding for Phoenix at 4:30pm (left) and Tucson (right) at 3pm this afternoon.<\/figcaption><\/figure>\n\n\n\n

The HRRR-UA WRF 15Z radar refelctivity forecast for this afternoon shows the storms in the Tucson metro area and staying east of Phoenix today.\u00a0Tucson is forecast to get two round of thunderstorms moving north, around 5-6pm and again 8-9pm. The gusts are not too high, generally in the 30 to 40mph range.<\/p>\n\n\n\n