A drastic weather pattern change is about to induce an acute case of weather whiplash for most of the country. During the next few days, a record-setting Western heat wave will settle in while winterlike cold returns to the East.
The heat wave in the West will dominate weather headlines for at least two weeks starting Thursday, as numerous locations are likely to set all-time heat records for the month of March.
The heat will melt the West's alreadywell-below-average snowpack, raising concerns for spring and summer water resources and a potentially severe wildfire season. The heat all but assures that Colorado and Utah will have their lowest snowpack on record.
"We're going to get to April first and we're going to see some very scary snowpack numbers essentially everywhere" across the West, University of California climate scientist Daniel Swain said this week.
The heat, which is already building in the Southwest, comes courtesy of a strong area of high pressure, or ridge in the upper atmosphere, also known as a heat dome. This weather feature is likely to park over the West without moving much for up to two weeks.
Downstream of the heat dome, the jet stream will dive south out of Canada, transporting cold air into the Midwest and East, along with chances for snowfall into mid-to-late March.
If this feels familiar, it is because this is the same pattern that brought multiple cold outbreaks and major winter storms to the East this winter, though the unusually mild weather this past week likely had residents thinking spring may have sprung.
Cities that saw high temperatures in the 70s and 80s this week are likely to see highs in the 30s and 40s next week.
Washington, DC, saw a high temperature of 84 degrees on Tuesday, but will drop into the 50s this weekend, and fall into the 40s early next week. Temperatures climbed into the 70s in parts of the Northeast on Tuesday, but multiple chances of more snow are back in the forecast there during the next five to seven days.
Advertisement
The cooldown may reach all the way into the Southeast, where parts of Florida could see lows in the 50s this weekend, potentially plunging into the 40s early next week.
While the impending cold snap in the East will feel like major whiplash, the weather shift in the West will be far more significant.
Deadly heat in March
The National Weather Service is warning residents of the Southwest in particular to prepare for unprecedented — and potentially deadly — March temperatures during what will be a long duration heat wave.
Phoenix is likely to see its earliest 100-degree day on record, beating the current record by more than 10 days, according to the NWS.
"Given the unprecedented length and magnitude of this extreme heat wave, heat stress will be increasing each day," NWS forecasters in Los Angeles said Wednesday. Extreme heat can be deadly, and is the top weather-related killer in the Lower 48 states annually.
This heat wave follows what was already the West's hottest meteorological winter – December through February – on record, with multiple states setting all-time warmest winter records.
Southern California is predicted to experience temperatures as much as 20 to 30 degrees above average for this time of year during the course of the next two weeks, the NWS warned.
Climate change increases the likelihood, duration, and severity of heat waves, and likely played a role in clinching the title for the West's hottest winter.
In addition, seasonal timing is shifting as the world warms. Across much of the US, winter is the fastest-warming season, and spring is also coming earlier in many areas with the last freeze happening sooner.
For more CNN news and newsletters create an account atCNN.com
