Sunday, June 28, 2020

Storms to carry severe weather, flood risks across large swath of US








A stagnant weather pattern has set up across the central and eastern United States, sparking daily rounds of showers and heavy thunderstorms into the start of July.

The stormy conditions will not only bring hazards such as severe weather and flash flooding to some communities, but also make it difficult for residents to find extended dry periods to exercise outdoors and complete yard work.

"Showers and thunderstorms will erupt daily into the middle of the week along a nearly stationary frontal boundary stretching from the northern Plains to the southern Atlantic Seaboard," AccuWeather Meteorologist Mary Gilbert said.

This boundary separates very humid air streaming in from the Gulf of Mexico from mainly dry and rather pleasant conditions across parts of the Great Lakes and the central Appalachians.

"Since this boundary will generally be sitting over the same corridor for several days, the flash flood risk will be heightened due to the repetitive nature of the downpours," Gilbert said.

Rainfall may come down at a rate of 1-2 inches per hour in the heaviest thunderstorms, which will make it difficult for all of the water to absorb into the ground.

Into Sunday night alone, a corridor from the lower Ohio Valley to the southern Appalachians could receive an AccuWeather Local StormMax™ rainfall of 6 inches due to repeating downpours.

Those who live near small creeks and streams should be wary of sudden rises in water levels.

"Those who must travel will need to watch out for ponding on roadways, especially in poor drainage and low-lying areas, and should never drive through floodwaters," Gilbert said.

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Even in the absence of flooding, motorists may face slower-than-normal travel as rain reduces visibility on the roadways and creates a heightened risk of vehicles hydroplaning at highway speeds. These hazards can be experienced on stretches of interstates 35, 40, 55, 65, 70, 80, 90 and 94, to name a few.

Bismarck, North Dakota; Minneapolis; St. Louis; Louisville, Kentucky; and Nashville, are a handful of the cities that can experience rounds of showers and heavy thunderstorms into the middle of the week, along with a heightened risk of flooding.

A portion of the thunderstorms each day into Wednesday can bring additional hazards.

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"Some of the thunderstorms can turn locally severe with damaging wind gusts being the primary risk," Gilbert said.

Part of the northern Plains and Midwest will be at greatest risk for such storms at the end of the weekend. These storms could contain large hail and perhaps even isolated tornadoes, in addition to the strong winds. The zone stretching from the lower Ohio Valley to the southern Appalachians could also experience gusty storms, along with the torrential downpours.

While locally heavy and gusty thunderstorms can occur yet again on Monday from the northern Plains to the Carolinas, Tuesday and Tuesday night may be the period of greatest concern for severe weather in the pattern, especially across the northern and central Plains.

Residents are reminded that regardless of the severity of the thunderstorms each day, any thunderstorm can produce potentially deadly lightning strikes, thus making it vital to seek proper shelter indoors as soon as thunder is heard.

Indications point toward the stagnant pattern breaking down across the North Central states during the latter half of the week, with drier air returning.

The zone of stormy weather may shift southward to focus more on the Southern states during this time. AccuWeather meteorologists are actively monitoring a scenario that could bring days of heavy rainfall and a heightened flood risk to this region late in the week and during the first weekend of July.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.


Window for tropical development closing for the East Pacific?

Updated Jun. 28, 2020 6:44 AM









The East Pacific tropical basin sprung to life this past week as multiple areas of tropical low pressure developed across the region, including one that became Tropical Storm Boris. However, that uptick in activity could be about to change, say AccuWeather meteorologists who have been closely examining the tropics.

After becoming a tropical storm briefly late in the day on Thursday, Boris has since weakened to a post-tropical low pressure area well to the southeast of Hawaii.

Behind Boris, there is one other area that AccuWeather forecasters are monitoring in the East Pacific Basin.

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A feature that emerged off the coast of Central America late this past week has a small window for development off the southwestern coast of Mexico.

The cluster of showers and thunderstorms remained disorganized on Saturday as it moved to the northwest, generally paralleling the coast of Mexico.

The disturbance is running out of time to develop tropically, however, as it will move into an area of drier air, increased wind shear and cooler water early this week.

"Even if the system were to develop, it would do so several hundred miles off the southwestern coast of Mexico and therefore be no threat to land," said AccuWeather Hurricane Expert Dan Kottlowski.

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The next system to strengthen into a tropical storm with winds of 39 mph (62 km/h) in the East Pacific Basin would be given the name Cristina.

At the same time, meteorologists have been monitoring Saharan dust pushing through the Caribbean Sea and into the Gulf of Mexico, which is helping to stifle widespread tropical development in the Atlantic Basin. Dolly formed outside of the large plume of dust this past week, more than 300 miles southeast of Nova Scotia, and became the second earliest fourth-named storm in recorded history in the Atlantic.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.

Howling winds to stoke wildfire risk over massive area of western US

Updated Jun. 28, 2020 6:42 AM









Firefighters, property owners and travelers are bracing for an unusually potent windstorm that is forecast to target a large portion of the southwestern United States through Monday.

"The period from June through August is typically a quiet time in terms of large-scale wind events over the southwestern U.S.," AccuWeather Senior Meteorologist Mike Doll said.

A portion of the Bush fire burns through the Tonto National Forest, Tuesday, June 16, 2020, as seen from Apache Junction, Ariz. (AP Photo/Matt York)

"Weather systems are often relatively weak as the jet stream has shifted northward into southern Canada and a large area of high pressure typically rules the Western states during the summer months," Doll explained.

There can be exceptions at times during the summer months. One such departure from the normal is anticipated into early week as a southward dip in the jet stream allows a storm to bring cooler air, rain and even summertime snow to parts of the West.

Winds will also align near the ground and high up in the atmosphere, to produce stiff breezes and strong gusts from the southwest and west.

Through Sunday night, the area that is likely to have wind gusts between 35 and 45 mph is forecast to extend over 1 million square miles of the Southwest from California to western Colorado and part of western New Mexico.

Within this zone, gusts reaching 45 to 55 mph with an AccuWeather Local StormMax™ wind gust of 70 mph can occur over the ridges, in wide-open spaces and through canyons from eastern California to much of Nevada, central Utah and northwestern Arizona.

Gusty winds were already wreaking havoc in portions of Utah during Saturday night. Approximately 30 homes were evacuated near Lehi and Draper, Utah, due to a growing blaze dubbed the Traverse Fire. The fire was reportedly caused by fireworks and was quickly fanned by the strong winds.

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On Monday and Monday evening, the swath of stiff breezes with strong gusts will extend from the southern parts of California and Arizona to western Colorado and south-central Wyoming. Once again, AccuWeather Local StormMax™ wind gusts are forecast to be in the neighborhood of 70 mph.

Not only will the gusty winds cause trouble for firefighters battling existing large wildfires in the region, but they will also greatly raise the potential for new blazes to ignite and spread rapidly.

A lower-than-average amount of rain and mountain snow during late winter and spring left places from Northern California and Oregon to Colorado and New Mexico to face abnormally dry conditions to extreme drought. Adjacent areas of the southern High Plains and portions of the Northwest are experiencing similarly dismal conditions.

The precipitation deficit, combined with dry air and surges of early-season heat, has led to dry soil and fast-drying vegetation.

Dozens of fires have erupted over the West in recent weeks.

As of June 26, more than 1 million acres have burned across the U.S. with the vast majority of the fires west of the Mississippi River, according to data from the National Interagency Fire Center.

Currently, active fires have consumed close to half of the 1-million-acre figure, the agency reported on Friday. More than three dozen fires were active in the West, and of these, there were a dozen large blazes in progress. The largest fires charred Arizona with the Mangum, Bush and Bighorn fires consuming hundreds of thousands of acres alone.

"With the expected conditions through Monday, the number of fires and acres burned may increase substantially," Doll said.

Lightning strikes from spotty thunderstorms, which are expected to arrive along with a transition from hot to cool weather, may also spark blazes in the region. However, cooler air and moist vegetation over some of the ridges and peaks will deter the fire risk over the high country.

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"You just don't typically see this kind of a large wind event this time of the year, and with many fires in place, it is going to be a major problem, to say the least," added Doll.

The invasion of much cooler air, combined with lesser winds, should ease the fire risk from west to east spanning Monday and Tuesday. Unfortunately, the damage may already be done by that point should new fires ignite and rapidly spread over the weekend.

People are urged to avoid the use of power equipment and open flames with the upcoming weather conditions. Experts recommend that people avoid parking a vehicle over dry brush as the exhaust system from an idling or recently used vehicle is hot enough to quickly start a blaze.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.

Striking cooldown to usher in rain, summer snow to parts of the West

Updated Jun. 28, 2020 6:27 AM








Cooler air will plunge southward across the West, bringing welcome precipitation for drought-stricken areas, and even some wintry precipitation for others.

A refreshing change in the weather pattern will replace the heat that has settled across the West over the past week. Temperatures were able to soar past 100 degrees Fahrenheit in cities from Medford, Oregon to Roswell, New Mexico, with some locations like Palm Springs, California, and Phoenix, Arizona, topping 110 degrees for several days.

A storm pushing south from Canada into Idaho will allow the jet stream to dip south, opening the door for cooler air and wet weather to infiltrate the Northwest.

Rain will spread from the Pacific Coast of Washington and Oregon on eastward through Sunday and Sunday night. As the cooler air collides with the warmth across the Rockies and Plains, thunderstorms along with drenching downpours will develop across much of Idaho and Montana.

The rain will be beneficial for many communities that have been battling drought conditions since the beginning of spring. As of Thursday, there were pockets of severe or extreme drought conditions from the San Francisco Bay area in Northern California through much of Oregon and into the Columbia Basin of Washington.

The combination of the cooler, Canadian air and the precipitation may allow for wintry precipitation in some of the higher elevations.

"Snow levels Sunday night and early Monday could drop as low as 6,000 feet in the northern Rockies of Idaho and Montana," AccuWeather Senior Meteorologist Dave Samuhel said.

There is a chance that just enough precipitation will extend southward into Utah on Monday, allowing snowflakes to fly in parts of the Wasatch Mountains as well.

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While the wet weather will remain near the center of the storm in the northwestern United States, the cooling effects the storm will extend much farther south.

"Temperatures will take a nose dive across Idaho and southern Oregon first on Sunday, and in northern Utah to Central California on Monday," Samuhel added.

Away from the coast, temperatures will drop as much as 30 degrees from their peak late this week into early this week, ending up near or below normal for late June across the region.

AccuWeather meteorologists forecast that Medford, Oregon, will struggle to reach the upper 60s on Sunday afternoon, a far cry from the high temperature of 98 degrees recorded on Friday.

After a high temperature of 107 degrees on Saturday, which is a staggering 10 degrees above normal, Fresno, California, can expect a high in the upper 80s on Monday, a more common temperature for late May.

Farther south, the cooler air will not be able to become fully entrenched. Instead of high temperatures over 100 degrees in Las Vegas, highs will only reach 90 degrees on Monday, a feat that has not occurred for the city since June 13.

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This pattern change will also create some difficult firefighting conditions for some of the ongoing blazes across the West.

"The jet stream diving southward will create a rush of strong winds through Monday from California and the Desert Southwest to the Rockies," said AccuWeather Senior Meteorologist Alex Sosnowski.

With wind gusts up to 55 mph in the higher elevations of California, to the Wasatch Mountains of Utah, this will allow existing fires or any new fires to spread rapidly.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.


Winds blow massive Saharan dust cloud into US airspace

Updated Jun. 28, 2020 12:07 AM









Dust from the Sahara Desert that has been pouring off the western coast of Africa and into the Atlantic has effectively put the Atlantic hurricane season on pause, with the exception of short-lived Tropical Storm Dolly, which formed on Tuesday, June 23, in the North Atlantic. The dust is largely impacting the Gulf Coast, but could push northward into the airspace above a few other states farther inland.

The robust plume of dust, which satellite imagery showed had reached into U.S. airspace by Friday, has been felt by many across the Caribbean, where it left behind a thin coating on the ground in some areas. The sky turned hazy over the U.S. Virgin Islands, Puerto Rico and Cuba, and visibility was drastically reduced in some areas. By Friday morning, the air quality in Galveston, Texas, where AccuWeather's Bill Waddell is stationed, had plunged from "excellent" on Thursday evening to "unhealthy."

Dusty skies were also observed in Panama City Beach on Friday morning, according to video posted on social media, and dust appeared to be hanging low in the skies over the Houston skyline, a photo posted on social media by Sergio Chapa showed.

"A quick glance out the window, it's easy to confuse it for fog," Chapa, a 44-year-old Houston resident told AccuWeather, adding that the haze looked like fog but with, "a slight brown tint."

"This is much different from ozone action days, but not quite like a forest fire," Chapa said. "I wear glasses and I was wearing a face mask. My eyes are fine, but even with the mask, my throat is irritating after talking around for about 30 minutes in the dust storm."

Dust is often pushed off the African coast during the early stages of Atlantic hurricane season, but the vastness of this episode has raised eyebrows. Some experts have described the plume as the most significant event in the past 50 years and even referred to it as a “Godzilla dust cloud,” according to The Associated Press.

The cloud is part of what's known as the Saharan Air Layer (SAL), which usually occupies a 2- to- 2.5-mile-thick layer of the atmosphere, with a base starting about 1 mile above the surface, according to the National Oceanic and Atmospheric Administration (NOAA).

AccuWeather meteorologists have been tracking dust emerging from the Africa coast since April, but there has been an uptick in activity since around June 14. Dust is most commonly observed over the Atlantic into July before it becomes less of an issue later in the hurricane season. AccuWeather's top hurricane expert Dan Kottlowski said the African Easterly Jet has been stronger than normal and this has produced more dust.

"Certainly the dust episodes in the Caribbean have been more robust than normal due to the active jet," Kottlowski said.

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Just this past week, the dust floated across the Caribbean into the southern Gulf of Mexico, and now forecasters say it'll hover over the Southern states through Sunday.

The dust is forecast to be primarily concentrated over Gulf Coast states, from Louisiana to Florida, but some could expand farther north into Alabama, Georgia, and Tennessee, Kottlowski said. He added that the forecast does not call for high concentrations of dust to play a role in the overall weather pattern across the northeastern U.S. Some dust could "barely" reach into southern Virginia, Kottlowski said. 

“Dust, like any pollutant, can find its way farther north over time and it’s possible some dust could work into the Great Lakes this week but it probably would not be very noticeable. A storm system forming in Canada over the weekend will move southeast into Maine early this week and bring a wind flow out of Canada and not up from the tropics,” Kottlowski said.

Dust particles can produce vibrant sunsets and sunrises, but if there is too much of an accumulation, then those sunsets or sunrises can turn out dull. Dust is usually most noticeable when the skies are cloud-free, according to Kottlowski. The cloud cover combined with the haziness from dust obscured the sunrise in Galveston on Friday morning, Waddell reported.

Air quality levels could also drop from moderate to unhealthy over southern and eastern Texas, according to Plume Labs. Those with respiratory issues are being urged to limit the amount of time they spend outdoors. AccuWeather and Plume Labs have a partnership that allows users to monitor the realtime air quality in a given location from the AccuWeather website or mobile app.

People watch the sunset while a cloud of Sahara dust hangs in the air in Havana on Wednesday, June 24, 2020. The massive cloud of dust was blanketing the Caribbean as it heads to the United States. (AP Photo / Ramon Espinosa)

Kottlowski said there is a second large area of dust over the Atlantic, likely to move into the eastern Caribbean on Sunday, but it seems less impressive than the first batch of dust currently invading the U.S. The second round of dust is likely to dissipate faster, thanks in part due to stronger winds forcing it westward. However, it will still bring a “considerable” amount of dust to the Gulf of Mexico early this week which will result in hazy conditions and milky-looking skies.

The presence of dust across the Gulf of Mexico, depending on its exact location, may inhibit tropical development into the early part of July.

Longer range forecasts show an easing in the amount of dust entering the atmosphere over the week as the African Easterly Jet, which is responsible for triggering the potent storms that kick up the dust, is forecast to relax a bit, according to Kottlowski.

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Additional reporting by Bill Waddell.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.

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