US weather forecast: Dangerous heat wave, severe thunderstorms and flash flooding to hit several states | Today’s news
A dangerous combination of extreme heat, severe thunderstorms, flash flooding and monsoon rains is expected to affect much of the United States through July 29, according to the Weather Prediction Center (WPC) of the National Weather Service (NWS).
As a powerful heat dome continues to scorch the central and southern US, several storm systems are forecast to bring damaging winds, hail and flooding from the upper Midwest to the Northeast. Meanwhile, the annual North American monsoon unleashes heavy downpours in the Southwest.
Here’s what’s happening and which places are most at risk.
Why is the US facing such extreme weather?
The Weather Prediction Center says a broad ridge of high pressure, often called a “heat dome,” is parked over the central and southern United States.
High pressure systems suppress cloud formation and trap hot air near the surface. The result is long periods of sunshine, sweltering daytime temperatures and unusually warm nights that prevent people and infrastructure from cooling down.
At the same time, a disturbance moving along the ridge’s northern edge collides with warm, moist air from the Gulf of Mexico, creating ideal conditions for severe thunderstorms.
Meanwhile, the Southwest remains under the influence of the North American Monsoon, which brings moisture from the tropics to support heavy rainfall and thunderstorms.
Which states are under a dangerous heat wave?
The most dangerous heat is expected in:
Parts of the Southern Rockies
Desert Southwest, including Arizona, Nevada, and southeastern California
Daily temperatures are forecast to reach:
-Upper 90s to low 100s°F (37°C-40°C) across much of the Plains and Southeast.
-Between 115°F and 120°F (46°C-49°C) in isolated parts of the desert southwest.
-Humidity will make conditions even more dangerous, with heat index values expected to exceed 105°F to 115°F (40°C-46°C).
-Nighttime temperatures are also expected to remain unseasonably warm, hovering around 70°F in many places, increasing the risk of heat-related illness.
The Weather Prediction Center has issued a major to extreme heat risk for much of the southern Plains, Mississippi Valley and Southeast.
Where are severe thunderstorms expected?
A cold front moving from the upper Midwest into the Ohio Valley will interact with warm, moist air to produce widespread thunderstorms.
Monday’s highest risk of severe weather covers the following areas:
The Storm Prediction Center has placed these areas at an increased risk (level 3 out of 5) for severe thunderstorms.
Forecasters warn that storms can cause:
Why are flash floods a concern?
Heavy rain falling repeatedly over the same places – known as practice storms – could quickly flood drainage systems.
The Weather Forecast Center has warned of flood risks in:
On Tuesday, a moderate risk (Level 2 of 4) for excessive precipitation extends from parts of:
Urban flooding, stream overflows, and rapidly rising water levels are possible, especially where storms repeatedly move over the same communities.
Which locations are experiencing the most severe weather on Tuesday?
Strong thunderstorms are expected further east as another upper-level disturbance moves into the Great Lakes.
Areas under moderate risk (level 2 of 5) include parts of:
Appalachian Mountains
Storms may again bring:
What’s happening in the Southwest?
The annual North American monsoon continues to bring moisture to:
Central and Northern Rocky Mountains
Frequent afternoon thunderstorms are expected in the Four Corners region, where Arizona, New Mexico, Utah and Colorado meet.
The weather forecast center warns that burn scars from previous wildfires, canyons, steep mountain terrain and urban areas remain particularly vulnerable to flash flooding.
Some thunderstorms over southeastern Arizona could also produce strong wind gusts.
Which other regions could experience flooding?
Repeated thunderstorms are forecast along:
East Florida, including parts of the Atlantic coast
Up to 15 cm of rain could fall in some areas, increasing the risk of flash flooding.
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When will the heat ease?
The arrival of a cold front will bring some relief to parts of the Midwest and Great Lakes.
However, dangerous heat is expected to persist in:
at least until the middle of the week.
What should residents do?
The National Weather Service advises people in affected areas to:
Stay indoors during the hottest part of the day whenever possible.
Drink plenty of water and avoid strenuous outdoor activities.
Never leave children or pets in parked vehicles.
Watch for weather warnings for severe thunderstorms and flash flooding.
If floodwaters begin to rise, move to higher ground immediately.
Read also | Heat Dome Triggers Record Temperatures In Texas, Oklahoma, Nebraska
