Lightning over Tucson. August 2024
Southern Arizona is coming off one of the driest winter and spring seasons on record, and meteorologists say those conditions could bring good storm chances as monsoon season ramps up in about a month.
As the region comes out of a La Niña winter, Meteorologist Glenn Lader with the National Weather Service in Tucson said the dry spring conditions help increase chances for a wetter season, thanks to the soil conditions and mountain snowpack.
“If you get a dry winter and a dry spring, there’s basically a feedback loop between some of the soil moisture and mountain snowpack…so lower snowpack and drier soil moisture tends to help that high pressure kind of set up to our north and east a little bit earlier, and that is the driving force of our monsoon,” he said.
Historical trends also show a tendency towards wetter summers following dry winters. In a comparison of winter precipitation and the following monsoon season’s precipitation, six of the 15 wettest monsoons happened after 10 of the driest winter seasons on record for Southeast Arizona, according to an analysis by Lader and meteorologist John Glueck.
Models are also forecasting above normal temperatures.
“We always get hot summers, but it may tend to be a little above what we normally see,” he said.
La Niña conditions contributed to Tucson’s second-driest winter on record, with only a quarter of an inch of recorded rain. Meteorologists say La Niña and El Niño conditions help predict winter weather more than summer monsoons, and the region is currently experiencing a neutral state, meaning neither La Niña or El Niño conditions are active.
Last year’s monsoon saw an active, early start in June. However, much of the southwest saw rainfall totals below to well-below normal in 2024. Much of the southern portion of the state is classified under extreme drought.
Monsoon season starts June 15 and runs through September 30.
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