by tyler | May 9, 2023 | CNN, weather
Spring rains will soak the South this week, which could put millions of people at risk of flash flooding, with the Weather Prediction Center highlighting an area that puts Houston in the bullseye for the worst of the potential flooding.
“Instances of flash flooding are considered likely from the middle and upper Texas Gulf Coast to areas inland across the southeast Texas Triangle, which includes the entire Houston metro region,” the prediction center said.
Several rounds of heavy rain are expected through the day Tuesday and into Wednesday as a stubborn area of low pressure lingers.
The prediction center has issued a Level 3 out of 4 risk for excessive rainfall Tuesday and Wednesday, as torrential rains target the Houston metro area as well as Beaumont, Texas.
More than 7 million people are under flash flood watches in southeastern Texas through Wednesday evening. The region could see rainfall rates as high as 2 to 3 inches per hour at times.
Forecast models are indicating as much as 3 to 7 inches of rain are possible through Wednesday, with some areas potentially getting as much as 10 inches.
“The probability for numerous significant flash floods events has increased,” the National Weather Service in Houston said. “There is an increased danger to lives and property due to flash flooding.”
The main concern will be for areas where storms begin to train, which occurs when storms roll over the same area for longer periods of time, leading to intense flash flooding.
Get your local forecast here
The prediction center also issued a broader area of excessive rainfall risk for much of southeast Texas and southwest Louisiana. This Level 2 risk includes places like Lake Charles, Louisiana, and College Station and Victoria, Texas.
The Level 2 risk broadens on Wednesday to include areas like Dallas, Shreveport, Louisiana, and Little Rock, Arkansas. These areas will most likely receive around 2 inches of rain, which will be heavy at times.
By the second half of the week, the excessive rainfall risk diminishes, though isolated showers and storms will remain in the forecast.
The threat for flooding will linger due to the already saturated soils.
by tyler | May 8, 2023 | CNN, weather
Spring’s severe weather season is in full bloom across the Midwest and Southern and Central Plains.
Over the weekend, more than 400 severe storm reports were recorded across the region, including hurricane-force wind gusts, hail the size of softballs, and a few tornadoes.
Thousands of people lost power Sunday morning after severe thunderstorms, which spawned two EF-1 tornadoes across southern Indiana, moved through the region. Duke Energy reported 17 poles were broken in Floyd and Clark counties during the storm.
Some of the same areas are at risk of seeing intense severe storms again today.
A Level 2 of 5 risk for severe storms has been issued across portions of the Mississippi and Ohio valleys where the main threats will be damaging winds and large hail. Some cities under threat today include St. Louis; Indianapolis; Cincinnati; Nashville, Tennessee; and Louisville, Kentucky.
Severe storms were already ongoing across this morning, causing more than 10,000 customers to lose power across Illinois, according to PowerOutage.us. More rounds of severe weather are expected later today.
This afternoon, storms will initially bring the threat of large hail the size of golf balls or greater, before transitioning into a damaging wind threat through the evening.
And although the severe storm environment is not favorable for tornado development, “there may still be an opportunity for a tornado or two with any supercell that can be sustained,” the Storm Prediction Center warned.
What is a supercell?
The storms on Monday are following a similar path to storms over the weekend.
An upper-level ridge of high pressure has settled in over the Gulf of Mexico and portions of the southern US. Under the area of high pressure, storms have trouble developing or sustaining severe levels due to sinking air, which inhibits thunderstorm growth. So instead, thunderstorms tend to “ride” or travel along the edges of the ridge, in this case impacting the Midwest and Ohio Valley.
Ridge-riding storms tend to affect the same areas over and over until the high pressure weakens or moves. And unfortunately for some areas where the stubborn pattern has been in place for the last few days, it is not expected to shift until the middle of the week or later.
“Training storms,” as meteorologists call them, bring the threat of flooding as heavy rain falls over already saturated soils.
The Weather Prediction Center has highlighted a large portion of the Midwest and Ohio Valley for flooding Monday, as they expect hourly rainfall totals of two inches per hour, with localized rainfall rates as high as 4 inches possible.
A flash flood watch is currently in effect for the city of Springfield, Illinois, until Tuesday morning due to flooding caused by an upstream dam release after heavy rain fell over the weekend.
Heavy rainfall of 3 to 7 inches fell Sunday across western and southern portions of Sangamon County, across the Lake Springfield watershed, which caused rapid rises on the lake, according to the National Weather Service office in Lincoln, Illinois.
Widespread additional rainfall totals of 1 to 2 inches are forecast across the Midwest and Ohio Valley through Tuesday.
Another byproduct of the high-pressure ridge is heat, building across the southern and central states.
“Temperature-wise, the warmest temperatures compared to normal will be most commonly found in the Nation’s Heartland and across the South,” the Weather Prediction Center said. “It will feel more like June from the southern High Plains to the Southeast coast through Tuesday as daytime high temperatures between 5 to 15 degrees above normal.”
High temperatures in the 90s will be felt across portions of Texas today and widespread 80-degree high temperatures will spread from the central Plains, across the Gulf Coast and into the mid-Atlantic.
By Tuesday, 90-degree temperatures will continue across portions of Texas and expand into Florida, Georgia, and the Carolinas.
The heat will ease slightly by Wednesday, but above normal temperatures will persist across much of the eastern US through the end of the week.
by tyler | May 1, 2023 | CNN, weather
Tornadoes are one of Earth’s most violent natural forces.
They have whipped up in all 50 US states – and across the globe – at various times of year, sometimes causing untold devastation. But despite strides in their study, there’s still so much scientists don’t know about them.
“There is no perfect formula for forming a tornado,” said CNN meteorologist Brandon Miller, a storm chaser who’s has been following and studying these storms since 2005.
“Sometimes, it may appear that a storm is in a perfect environment for a tornado to form, yet it never does. Conversely, tornadoes frequently form in marginal environments where it seems like one or more ‘ingredients’ to storm formation is missing or lacking,” he said.
Still, there are some common factors anyone can look for to understand the life cycle of a developing storm that could produce a tornado. They are:
In the developing phase of the thunderstorm, warm air rises and fluffy white cumulus clouds begin to grow.
The clouds grow taller and taller, even before rain or thunder appears.
Then, the bottom of the clouds darken and the very top could flatten out, creating a protruding anvil shape that indicates very cold air at the top and could be a precursor to hail.
As warm as rises, cold air is pushed down. This results in wind speed and direction changing with height within the storm – a phenomenon called wind shear.
Wind shear helps the storm begin to rotate and become what’s called a supercell.
In this maturing phase, heavy rain, lightning, hail and very strong winds are expected.
Sometimes, a strong gust of wind – called a gust front – blows a few moments before rain arrives. It’s caused by cool air being forced down from the storm cloud. When the cold air hits the ground, it spreads out quickly ahead of the storm and is a sure sign a storm is near.
“Nearly all supercells produce some sort of severe weather (large hail or damaging winds) but only 30 percent or less produce tornadoes,” said the National Oceanic and Atmospheric Administration.
Tornadoes usually form from supercells when the right ingredients are in place to help them thrive:
• instability in the atmosphere, which allows air to rise;
• lift, the rising itself;
• and most critically, wind shear: when winds at different heights within the supercell blow in different directions.
The wind shear creates a horizontally rotating column of air within the thunderstorm cloud.
Then, two key forces inside the supercell can act on the rotating air column:
• the updraft – or the rising of warm air – lifts the horizontal air column,
• while the downdraft – an area of drier air pushed down from the storm – twists the column so it’s vertical, then wraps around its backside.
The resulting vertical column of air is called a funnel cloud until it touches the ground – when it becomes a tornado.
“The most telltale sign that a tornado could be forming, when you are looking at a close-range severe thunderstorm, is the ‘wall cloud,’” Miller said.
The wall cloud is a lowering of the darkened cloud base that leads to the air rotation. While the presence of a wall cloud doesn’t always mean a tornado will form, it certainly ups the odds.
“You will know you are looking at a wall cloud because it will hang noticeably lower than the rest of the thunderstorm, and you may notice it is rotating if you look closely,” Miller said.
Tornadoes can disappear as quickly as they appear – often morphing from roaring funnels of fury into nothing in seconds – when a key ingredient is lost, Miller said.
Sometimes as a thunderstorm evolves, its source of warm, moist air is cut off, causing a tornado to die, he said.
Tornado-producing supercells also can merge with other storms, forming into a so-called “squall line,” which generally kills a tornado, Miller said. Squall lines, though, have their own dangers, including gusty winds that can stretch for hundreds of miles – and even spin up quick tornadoes of their own.
by tyler | May 1, 2023 | CNN, weather
In the Midwest, the unofficial start to summer with barbecues seems a little far-fetched as people are still shoveling and having to clear snow off their grills before they even think about using them.
Another late-season storm is bringing wintry conditions this week to parts of the Midwest and Ohio Valley. Heavy snow, torrential rain, gusty winds and possible record cold high temperatures will make for a pretty miserable start to the week weather-wise.
Meteorologists from the National Weather Service office in Marquette, Michigan, are describing the event as “a historic late spring snowstorm the likes of which we have not seen here in Upper Michigan since May of 1990.”
Parts of Michigan’s Upper Peninsula have already seen up to 18 inches of snow and another two feet are possible through Tuesday.
“Given the late-season event, surface temperatures hovering around freezing will lead to a very heavy, wet snow, which may result in downed trees and powerlines,” the Weather Prediction Center said.
Along with heavy snow, winds will be gusting up to 50 mph across the Upper Midwest, which will add to the danger of falling trees.
The reason is a strong area of low pressure, which has stalled out over the Great Lakes region. It is bringing strong effects, felt for a longer duration, simply because the storm is not moving.
“Several locations (are) potentially approaching May monthly low-pressure records,” the prediction center mentioned in its forecast discussion.
As barometric pressure drops, it can be an indication of how strong a storm is. In this case, the pressure over the Great Lakes is equivalent to a strong tropical storm or low-end Category 1 hurricane.
The steady stream of strong winds will cause incredible wave heights across portions of the Great Lakes as well.
“The strong north winds will cause waves to build into the 15 to 20 feet range along the shores of Lake Superior today into tonight resulting in possible lakeshore flooding for portions of eastern Marquette and Alger counties,” the weather service office in Marquette said.
Flood watches are in effect across the region for not only the lakeshore flooding, but the additional river rise expected from snowmelt.
Temperatures across the Midwest, Great Lakes and Ohio Valley are running 10 to 20 degrees below normal early this week and more than 60 cold temperature records could be broken.
Here are a few cities expected to break records for cold high temperatures. All will experience temperatures more typical for early March:
The system will finally push out by midweek, moving into the mid-Atlantic and Northeast by Wednesday. I know many of you in the Northeast are tired of rain, after the miserable and dreary weekend, but this week is unfortunately going to remain unsettled. Rain and normal temperatures will settle in.
“Below-average temperatures will spill into the mid-Atlantic and Northeast, with nighttime lows dipping into the low 40s across nearly the entirety of the I-95 urban corridor,” the prediction center said.
Some of the higher elevations like the Pocono Plateau could even see a little snow.
“If some wet flakes do mix in, no impacts are expected (besides asking yourself “isn’t it May?”),” the weather service office in New York City pointed out in its forecast discussion.
For the rest of the Northeast, the precipitation type will be all rain, on top of what has already been a soaking weekend.
Yesterday Portland, Maine set a new daily rainfall record after picking up 2.5 inches of rain. Central Park in New York City also broke a daily rainfall record on Saturday after recording 2.46 inches of rain.
Much of the late-season misery should be pushed out by the second half of the week, nudging temperatures warmer and closer to where they should be this time of year, just in time for the weekend.
by tyler | May 1, 2023 | CNN, weather
The strength of tornadoes is rated on the Enhanced Fujita, or EF, Scale.
The scale runs from 0 to 5 and rates tornadoes after they’ve hit by assessing damage to determine wind speed. Estimates are based on damage to trees, institutional buildings and homes, making it harder to gauge tornadoes that leave little damage or happen in open space.
The scale is named after Tetsuya “Ted” Fujita, an engineer and meteorologist who developed the original version of it in 1971.
Here are the Enhanced Fujita Scale ratings used today by the National Weather Service and the kind of damage associated with each:
These tornadoes are the least destructive and typically break tree branches, damage road signs and push over small, shallow-rooted trees.
With similar wind speeds to weak hurricanes, these tornadoes can push moving cars off course, shift mobile homes from their foundations and remove roof surfaces.
Significant damage starts to emerge from these tornadoes, which can snap or uproot trees, destroy mobile homes and tear roofs completely off homes.
They also can pick up small objects and turn them into dangerous projectiles.
These tornadoes produce severe damage, uprooting nearly all trees in their path, blowing over large vehicles like trains and buses and significantly damaging buildings.
Less than 5% of all tornadoes are rated EF3 or higher.
One such tornado in March 2022 struck near New Orleans, hitting Arabi, Louisiana, with 160-mph winds. At least one person was killed and eight hospitalized after the storm ripped through homes and businesses, leaving a trail of destruction.
Easily destroying homes, tossing cars and downing large trees, these tornadoes can be devastating.
One ripped through eastern Alabama in 2019 with top winds estimated at 170 mph. Blazing a track a mile wide, it killed at least 23 people, including three children.
Another EF4 tornado was part of an outbreak that tore through eight states just two weeks before Christmas 2021. It destroyed part of Mayfield, Kentucky, and left at least 74 people dead in that state alone.
These monsters cause complete devastation, flattening nearly everything in their path.
They are rare, with only 59 have been recorded in the United States since 1950, according to the Storm Prediction Center.
The most recent struck in 2013 in Moore, Oklahoma, killing 24 people, including several students at an elementary school where only a few walls were left standing.
by tyler | Apr 28, 2023 | CNN, weather
Parts of the South are yet again at risk of facing severe storms Friday that could bring damaging winds, large hail and the possibility of tornadoes to millions in north-central Texas.
More than 12 million people in Texas, including the Dallas-Fort Worth area, are under a significant risk for severe thunderstorms, according to the Storm Prediction Center. The Level 3 of 5 threat includes Dallas, Fort Worth, San Antonio and Austin.
The state could see baseball-size hail and wind gusts reaching hurricane speeds of 74 mph or higher. A few tornadoes are also possible into the afternoon and early evening, forecasters at the National Weather Service in Fort Worth said.
Much of the rest of east Texas is under Level 2 threat, including Houston, the Weather Prediction Center said.
“Large hail will be the primary threat with supercells, with a couple of instances of 3+ inch stones possible,” the prediction center warned.
Large hail, high winds and a couple of isolated tornadoes are possible along the borders with Oklahoma and Arkansas, according to the prediction center.
The severe weather threat comes as another storm system triggered tornado reports, gusty winds and dangerously large hail in Texas and Florida this week.
On Thursday evening, the storm whipped up a tornado near Hosford, Florida, after which a dozen homes were destroyed and about 20 others were damaged, according to Rhonda Lewis, the head of Liberty County Emergency Management.
Six of the seven tornado reports recorded Thursday were across the Florida Panhandle, while one was in southwestern Georgia.
In addition to the tennis-ball-sized hail that bombarded parts of Texas and Florida on Wednesday, hail 1.75 inches wide was also reported Thursday in multiple Florida cities, and thousands in northern Florida were left without power.
The two storm systems hitting the US on Friday have put more than 50 million people in the South and mid-Atlantic under thunderstorm risks.
The various levels of threats extend across the entire eastern half of Texas, where storms should develop this afternoon. There’s a threat of tornadoes before the storms form a line and race across the eastern part of the state in the evening.
Storms forming across North Texas, including the Dallas area, this afternoon will have the greatest threat to produce a few tornadoes.
By the evening, the threat will transition to more of a damaging wind risk, which could lead to widespread power outages.
As for the Southeast, there’s a marginal risk for thunderstorms stretching from South Florida northward to Virginia. The warned area includes Miami, Jacksonville and Tampa in Florida; Savannah, Georgia; Charleston and Raleigh in the Carolinas; and Roanoke, Virginia.
By Saturday, most of the severe weather will be winding down. While there’s still some uncertainty in the forecast, New Orleans, Montgomery and Mobile, Alabama, and Orlando and Tampa, Florida, could see damaging winds, hail and even an isolated tornado.
