The Southwest monsoon will remain active on Thursday, bringing both beneficial rain and a risk of flash flooding to some areas in New Mexico, Arizona, Colorado, Utah and Nevada.
Some locations that can be hit by thunderstorms are Tucson and Flagstaff, Ariz., Grand Junction, Colo. and Santa Fe, N.M.
The more intense thunderstorms, which not everyone will see, can produce wind gusts over 50 mph, torrential downpours and flash flooding.
Thunderstorms will initially develop over the mountains then slowly drift over the lower elevations. The slow movement is one aspect that can make these thunderstorms prolific producers of rain in a monsoonal pattern, and this will be the case today.
Runoff from these downpours will cause rapid water rises in creeks and quickly turn normally dry washes (arroyos) into raging rivers. This can pose a danger miles away and downhill from the heavy rain.
If you are hiking through a dry wash or valley and observe a thunderstorm in the distance, you should seek higher ground, as water can fill up a dry wash with torrents of water and debris with little notice.
Another hazard will be lightning, and it takes just a single strike to spark a wildfire since the region is still dry despite the recent rainfall.
Gusty winds from thunderstorms today can create blowing dust and reduce visibility to near zero, making travel extremely challenging. Interstates 10, 25 and 40 are in the threat area.
Once evening arrives, showers and thunderstorms will gradually weaken with light showers in a few spots leftover during the night.
Tropical Depression Seven strengthened into Tropical Storm Gaston during Monday night with another system attempting to form near the Caribbean.
Following a fall-like start to the week, warmth and humidity will build over the northeastern United States prior to the weekend.
A budding tropical disturbance has the potential to reach Florida with gusty winds, showers and thunderstorms during Sunday and Monday.
The return of warmer and more humid air will trigger another round of strong thunderstorms across the central United States this week.
Several days of intense heat will build across France this week with temperatures approaching 38 C (100 F) in many locations.
Chesapeake Bay Area (1933)
Hurricane - 6.39 inches of rain in Washington, D.C. Damage in Maryland close to $17 million. Tide 7 feet above normal flooded Norfolk, VA.
Dry thunderstorms ignited more than 100 fires in the Wenatchee and Okanogan National Forests.
Dallas/Ft. Worth, TX (1980)
105 degrees -- the 60th consecutive day with a high temperature of at least 100 degrees.