Higher than normal temperatures expected to lead to floods in Yosemite, forecasters say

The near future was expected to see higher-than-normal temperatures in Fresno and the central San Joaquin Valley as many fear a quick snowmelt, meteorologists said Monday.

The week began with a high temperature in Merced of about 81, which was about 5 degrees higher than the historical average, and similar conditions were expected Tuesday, according to the National Weather Service in Hanford.

The highs were also forecast to continue to climb peaking at about 92 degrees by Thursday in Merced.

Meteorologist Andy Bollenbacher said the highs could be 10 to 12 degrees higher than normal by the weekend.

The greatest emphasis of forecasters Monday was on the Merced River and Tenaya Creek in Yosemite National Park where flooding is likely around Pohono Bridge, he said.

“(We’re) pretty confident that it’s going to happen especially as we get into Friday, Saturday and Sunday,” he said. “We’re just monitoring the situation as it unfolds.”

There is a 75 percent to 90 percent probability for the Merced River at Pohono Bridge to reach 12.5 feet during the first full week of May, the service said.

Flood stage for Merced River is 10 feet and the waterway was expected to reach that level by 11 p.m. Thursday, the service said.

“We’re looking at some short-term high-impact flooding issues,” Bollenbacher said.

That means roadways near the river on the eastern edge of Yosemite National Park will likely flood and become impassible, forecasters warn.

Bollenbacher stressed that flooding was in the park and not expected to be a flood hazard in the lower parts of the Merced River in places like Planada, which have already been ravaged by water damage.

Forecasters in the region said waterways will be full and fast-moving, and don’t forget cold. They warned that people should stay out of the water.

The heavy melting of snow also brings the potential to bring more water to Tulare Lake, which has seen its basin fill after several weeks of atmospheric rivers.

The Kings, Kaweah and Tule rivers each feed into the lake. Heavy winter rains poured so much water on the Sierra foothills that dam operators at Pine Flat Lake, Lake Kaweah and Lake Success had to make flood control releases.

A significant amount of that water ended up on what is now farmland in the old Tulare Lake bed in Kings and Tulare counties.

Weekly forecast in Merced

Merced is also expected to experience a lower-90s heat wave toward the end of the week with sunny days and mostly-clear nights.

• Monday- High of 81; low of 50
• Tuesday- High of 82; low of 53
• Wednesday- High of 88; low of 57
• Thursday- High of 92; low of 59
• Friday- High of 90; low of 58
• Saturday- High of 89; low of 56
• Sunday- High of 88

Heat-sensitive populations

The weather service describes heat-sensitive groups as populations who may need to take actions to prevent heat-related illness at risk levels that may be below current NWS heat product levels.

Those groups, according to the weather service, are:

• The elderly and the very young
• Those on certain medications and/or those with preexisting conditions which make them more sensitive to heat
• Those working outdoors, especially new workers, temporary workers or those returning to work after a week or more off
• Those exercising or doing strenuous activities outdoors during the heat of the day, especially those not used to the level of heat expected, those who are nor drinking enough fluids or those new to that type of activity
• Those without a reliable source of cooling and/or hydration
• Those not acclimated to the level of heat expected, especially those who are new to a much warmer climate

Preventing heat-related illness

Stay cool, stay hydrated and stay informed are the Centers for Disease Control’s three key tips to avoid mild to severe heat-related illnesses in high temperatures.

To stay cool, the CDC recommends limiting outdoor activities to when it’s coolest and if you are outside when it’s hot, rest often in shady areas so your body has a chance to recover.

Sunscreens labeled “broad spectrum” or “UVA/UVB protection” work the best to prevent sunburn, according to the CDC.

Avoid hot and heavy meal in warm weather, as they add heat to your body.

The CDC says electric fans may provide comfort, but when the temperature is in the high 90s, they will not prevent heat-related illness. Move to an air-conditioned area or take a cool shower to cool off.

To stay hydrated, the CDC says don’t wait until you’re thirsty to drink. If your doctor limits the amount you drink or has you on water pills, ask how much you should drink while the weather is hot.

Very sugary or alcoholic drinks cause you to lose more body fluid, so these should be avoided. Ice-cold drinks may be satisfying in hot weather, but, according to the CDC, they can cause stomach cramps.

Use a buddy system when working in the heat to monitor the condition of your co-workers and so someone can do the same for you.

People aged 65 or older should have someone check on them twice a day during a heat wave.

Check for weather updates, extreme heat alerts and learn about cooling shelters to stay informed.