“The stage is set for Southern Arizona and New Mexico to receive potentially abundant rainfall and widespread flash flooding today,” as a low-pressure system brings moist, tropical air to the southwest in the form of heavy rain and thunderstorms to add to the already active monsoon season across the region, the Weather Prediction Center said early Saturday morning.
Widespread rainfall totals of 2 to 3 inches, with locally higher totals of 5 to 7 inches, are forecast across the region – giving the WPC a level 3 out of 4 “moderate” risk for excessive rainfall ahead of the wet forecast. That could mean widespread flash flooding in the Southwest.
“Urban locations, in addition to areas with complex terrain, are especially vulnerable to flash flooding and can quickly turn into very dangerous situations,” the WPC added.
The plume of moisture and heavy rain is expected to move into northern Texas from Sunday to Monday — where a Level 2 out of 4 “slight risk” for excessive rainfall has been issued. Rainfall of nearly 2 to 3 inches per hour is possible, according to the WPC.
“Urban areas will be most vulnerable to flooding during the period, even with the extremely dry, drought conditions.”
More than 90% of the state of Texas is currently experiencing drought, with nearly 62% experiencing extreme or exceptional drought — the highest categories.
Uncertain whether potential tropical cyclone four will strengthen
The hurricane center uses the potential tropical cyclone designation to provide warnings for a system before it actually gets a name.
A tropical storm warning is in effect for Mexico’s Gulf Coast from Boca de Catan north to the mouth of the Rio Grande — and across the lower Texas coast, from Port Mansfield south to the mouth of the Rio Grande. Tropical storms are expected in these regions for the next 12 to 24 hours as the system approaches the coast.
The system is expected to reach the coast of northeastern Mexico late Saturday afternoon, pushing inland through Sunday. There is still uncertainty about whether the system will strengthen enough to become a named storm before making landfall. If so, it will be named Danielle.
“There remains uncertainty as to whether the disturbance will be able to develop a closed surface circulation — and become a tropical cyclone — before reaching shore later today,” the NHC said. An Air Force Reserve reconnaissance flight scheduled for later Saturday morning should provide more information.
Still, heavy rain of 1 to 3 inches, with isolated totals up to 5 inches, is forecast in parts of Texas and Mexico over the next 48 hours, potentially leading to localized flooding.
CNN’s Ray Sanchez contributed to this report.