{"id":3042,"date":"2026-06-25T17:32:31","date_gmt":"2026-06-25T17:32:31","guid":{"rendered":"https:\/\/discussions.weather.arizona.edu\/?p=3042"},"modified":"2026-06-25T17:33:26","modified_gmt":"2026-06-25T17:33:26","slug":"moisture-decreasing-fire-weather-threat-increasing-june-25th-2026","status":"publish","type":"post","link":"https:\/\/discussions.weather.arizona.edu\/?p=3042","title":{"rendered":"Moisture decreasing, fire weather threat increasing: June 25th, 2026"},"content":{"rendered":"\n

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

Moisture is gradually moving east across Arizona, leading to drier conditions as westerly winds bring in dry air from the west. While some showers are happening in Northern Arizona, most rain evaporates before reaching the ground except in mountainous areas, where slightly more precipitation is possible. <\/p>\n\n\n\n

UA WRF model forecast and observed soundings indicate that moisture is decreasing, especially at lower levels, and the potential for storms is limited mainly to higher terrain today. By tomorrow, storm chances drop further as the moisture shifts east, with only isolated storms expected in New Mexico. Strong winds, low humidity, and dry conditions are increasing fire weather risks across Arizona into the weekend. Looking ahead, forecasts show little rainfall is likely through early July, with only eastern Arizona possibly seeing some monsoon accumulations, according to the ECMWF model.<\/p>\n\n\n\n

Yesterday’s Weather<\/h2>\n\n\n\n

Moisture continues to move into Arizona along two axes, shown below. The one depicted further west is pulling moisture from the tropical eastern Pacific northward into western Arizona, Nevada, and Utah. Storms dropped up to a half inch of rain in Northern Arizona at the Grand Canyon, westward to Las Vegas. The second moisture axis extends from the Sierra Madre mountains in Mexico northward into southeast Arizona.<\/p>\n\n\n

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GOES-19 upper-level water vapor images from June 24th at 6pm, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n

The thunderstorms associated with moisture flow from the Sierra Madre produced some locally heavy rain near Sierra Vista, as shown on the Rainlog plot below. <\/p>\n\n\n

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24-hour accumulated precipitation from Rainlog gauges, Santa Cruz and Cochise counties<\/figcaption><\/figure>\n<\/div>\n\n\n

An isolated thunderstorm developed near Gila Bend and produced light rain and lightning into the northwest Phoenix metro area. The HRRR-UA WRF 12Z forecast (below, left) missed this small feature and also some activity on the Cochise\/Graham county line, and the easternmost part of New Mexico. <\/p>\n\n\n

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HRRR-UA WRF 12Z 24-hour accumulated precipitation forecast (left) and corresponding observed precipitation from MRMS (right)<\/figcaption><\/figure>\n<\/div>\n\n\n

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

Moisture is slowly moving eastward and out of the state as westerlies aloft are bringing in dry air from far western Arizona. Visible satellite and radar show the moisture axis from Yuma northeast to Flagstaff and east to northern New Mexico. The Phoenix sounding (shown later) has the base of these showers above 12k. Therefore, away from the mountains, the rain from these showers must fall through a dry atmosphere, meaning only a few hundredths reach the ground. In the mountains, there\u2019s less distance for drops to fall, so they could receive between one and two tenths.<\/p>\n\n\n\n