Labor Day deluge may bring gusty winds, flooding

High end rainfall

(Image credit: NWS-Miami)

If rainy days and Mondays always get you down, look for a double-whammy on Labor Day, with the potential for heavy rain, gusty winds, and flooding, the National Weather Service in Miami says.

The culprit is the tropical wave north of Hispaniola that’s getting ready to move into the Bahamas on Saturday. It’s been getting more attention from the National Hurricane Center, which on Saturday jacked up development chances to 50 percent over the next five days.

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(Image credit: NHC)

The best chance for the system to become the season’s seventh tropical depression — or Tropical Storm Gordon — will be in the Gulf of Mexico after it exits the Florida peninsula, forecasters said. But the chance of development before it rakes the peninsula Sunday night and Monday went from near zero to 20 percent.

Heaviest rain should be focused on Florida’s East Coast. “This will be closely watched over the next couple of forecast cycles and if current trends hold, a Flood Watch may need to be considered for at least parts of South Florida for the Sunday Night/Labor Day,” NWS forecasters said.

The NHC promoted Tropical Depression Six, in the far eastern Atlantic, to Tropical Storm Florence early Saturday morning. Forecasters said some gradual strengthening was expected, but the more troubling news is a westward trend in the track forecast.

There are concerns that Florence may stay weak enough as it traverses the Atlantic to miss a break in the ridge, and eventually work its way far enough west to threaten the U.S. East Coast.

Here’s what the NHC’s Robbie Berg had to say about it: “After 48 hours, the storm is expected to reach a break in the ridge, causing it to slow down and turn northwestward by day 5. The biggest change noted among the track models on this cycle was a westward shift in the overall guidance envelope.

“The European model, in particular, swung significantly to the left, showing a weaker Florence not feeling the break in the ridge quite as much. I’d like to see this trend continue before making a significant change to the forecast, so for now the updated NHC track prediction is only nudged westward. That said, the models appear to be trending away from a definitive recurvature scenario.”

Saturday’s early run of the European put Florence disturbingly close to the Bahamas as a 975mb hurricane on September 11.

For the system headed to Florida, the GFS showed some weak development in the northern Gulf of Mexico by the middle of next week; the European had it spinning up off Florida’s West Coast on Tuesday after moving through the Keys; and the Canadian (CMC) projected development near Key West on Monday before moving west toward Texas as a strong tropical storm.

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AUGUST/ SUMMER WRAP: Friday was the end of the meteorological summer, but don’t bother searching the back of your closet for your sweater collection quite yet. The first cold front of autumn usually occurs around the middle of October, which is the same time as the end of the rainy season.

Here are a few precipitation stats for August and warmest June-August temperatures around the state:

Miami recorded 9.58 inches of rain in August, 0.70 above average. Warmest summer temp: 94 on June 21 and 22; July 21 and 23; and August 10. The highest June-August temperature in Naples was 96; Fort Lauderdale, 95 and West Palm Beach, 94.

Key West reported an August precipitation shortfall of 3.49 inches (1.89 inches fell). Highest summer temp was 94.

Orlando, 6.72 inches in August, a 0.41 shortfall. Warmest summer temp 95 on July 12.

Tampa, 14.50 inches, plus-6.83 for August. Highest summer temp, 96 on August 17.

Jacksonville, 7.68 inches of rain in August, 0.88 above normal. Warmest summer temp: 98 on June 21.

Tallahassee, August rainfall 11.48 inches, 4.13 above average. Hottest summer temp: 98 on June 20.

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A year after Irma, tropical weather weighs on Labor Day forecast

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UPDATE: The season’s sixth tropical depression formed late Friday in the far eastern Atlantic.  The National Hurricane Center dropped its forecast for the system to become a hurricane, and said it would likely curve north, well east of the Lesser Antilles.  (Image credit: NHC)

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The NHC increased chances of development for the Hispaniola low over five days to 20 percent on Friday night. (Image credit: NHC)

It’s Labor Day weekend and that usually means cookouts, get-togethers with friends and family — and tropical concerns.

This year is no different with the tropical wave near Hispaniola expected to wash over the Florida peninsula on Monday, and a storm in the eastern Atlantic that’s expected to become Tropical Storm Florence on Friday.

For now, there’s nothing nearly as dire as what was going on last year on Labor Day weekend.

The headline on Florida Weather Watch on September 2 was: Florida anxiously eyes Irma.

“NOAA’s GFS and the European forecast model (ECMWF) have been coming into closer agreement on a longer-term path for Hurricane Irma. But one thing they agree on already: This is going to be a doozy.

“Saturday’s run of the European showed a 921-mb hurricane passing over or near Grand Bahama on Sunday, September 10; The GFS had a 925-mb storm about 400 miles to the east of Grand Bahama next Friday. For comparison purposes, Hurricane Harvey had a minimum central pressure of 938 mb when it slammed into Texas as a Category 4 with 130 mph winds.”

A few days later, forecast tracks seemed to settle on a hit to Florida’s East Coast, causing many residents to hit the road. Then finally, Irma battered the Keys and raced up Florida’s West Coast.

Things look relatively benign this year, but conditions can change on a dime. The Hispaniola low, which is being watched by the National Hurricane Center, is unlikely to develop into a depression or tropical storm before it slides over South and Central Florida, and the Keys, on or around Labor Day.

“But environmental conditions could become less hostile when the system reaches the eastern Gulf of Mexico during the early to middle part of next week,” NHC forecasters said in their early Friday analysis in Miami.

AccuWeather, meanwhile, is calling for increasing showers, gusty winds and choppy seas as the wave approaches Florida.

National Weather Service forecasters in Tampa warned on Facebook of “an increased threat of heavy rainfall and possible flooding early next week.” NWS-Miami is also talking about possible minor flooding on Monday and Tuesday.

On the other side of the Atlantic, the low forecast to become Tropical Storm Florence was threatening the Cabo Verde Islands off the coast of Africa. Although chances seem high that the storm will make a right turn and head north into the open Atlantic, this is not a done deal.

A few members of the GFS Ensemble group on Friday were calling for a more westerly track so, as usual, it’ll be a wait-and-see scenario over the next week.

A few other storms are likely to pop up in the Atlantic over the next couple of weeks as conditions become more favorable for tropical development, Colorado State University hurricane researcher Philip Klotzbach said Thursday.

Late weekend precipitation chances in Central Florida, South Florida and the Keys range from 60-70 percent, according to the National Weather Service.

Tropical wave may make holiday weekend splash

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PM UPDATE: The National Hurricane Center now gives the tropical wave near Hispaniola a 10 percent chance of developing over the next five days, most likely in the eastern Gulf of Mexico.  “Regardless of development, this system could produce enhanced rainfall across portions of Hispaniola, the Bahamas, the Turks and Caicos, and Florida into early next week,” NHC forecasters said.

Here’s what the afternoon satellite image looked like:

Full Disk - Clean Longwave Window - IR

WAVE ON ITS WAY WEST: This formidable tropical wave, which was near Puerto Rico Thursday, was poised to bring wet weather to southern and central parts of the Florida peninsula over the holiday weekend, the National Weather Service said. The wettest day could be Monday or Tuesday, depending how the scenario unfolds, since there’s some disagreement on timing between the two major forecast models, the GFS and the European (ECMWF). After the wave crosses the Florida peninsula, there’s a possibility it could develop into a tropical depression or storm in the Gulf of Mexico, according to Weather Underground.  Below is the projected seven-day rainfall for Florida and the Gulf Coast from NOAA’s Weather Prediction Center.  For now, heaviest amounts are focused on the peninsula’s southeast coast and the Keys, followed by the northern Gulf Coast. (Image credits: Above, NOAA; below, WPC)

7 day rainfall

Meanwhile, the National Hurricane Center began advisories on Potential Tropical Cyclone Six late Thursday morning. Forecasters predicted it would become Tropical Storm Florence by Friday and Hurricane Florence by Sunday as it moves west-northwest, and then northwest across the Atlantic. Tropical Storm Warnings were posted for southern parts of the Cabo Verde Islands. Some forecast models are ramping it up into a hurricane after it batters the Cabo Verde Islands off the coast of Africa. Luckily — for now, at least — it appears this storm will curve north into the Central Atlantic and not bother the U.S. Coast. Note that if the Gulf of Mexico system would develop after the eastern Atlantic low, it would be named Gordon. That would be followed up by Helene and Isaac. Here are forecast models for PTC Six:

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(Image credit: SFWMD)

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TROPICAL UPTICK: Hurricane experts have been ratcheting down their forecasts for the 2018 hurricane season, which is now hitting its peak. On Thursday, for the first time this summer, researchers at Colorado State University called for normal tropical cyclone activity in the Atlantic, citing the new Potential Tropical Cyclone in the eastern Atlantic, and possible development in the Gulf of Mexico next week.

In addition, CSU’s Philip Klotzbach and Michael Bell said in their analysis covering the next two weeks: “There is the potential for another easterly wave developing into a tropical cyclone in 7-10 days near the Cabo Verde Islands.

“The Madden-Julian Oscillation (MJO) is forecast to be relatively weak in week one, and potentially amplify into phases 8-1 in week two. These phases tend to be associated with relatively active periods for Atlantic hurricane activity.”

The MJO is an environment that favors the development of thunderstorms and lower pressures over the oceans and travels across the globe in tropical regions.

The next week to 10 days could be interesting, but let’s hope it’s not too interesting.

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Shadows over peninsula

SATELLITE EARNS ITS STRIPES: Clouds associated with showers and thunderstorms approaching Florida’s East Coast cast early morning shadows across the peninsula in this satellite image. (Credit: NOAA/ NWS-Melbourne)

Wave watchers weigh impacts on Florida’s holiday weekend

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The seven-day rainfall forecast from NOAA shows heaviest precipitation potential in the Florida Straits and Keys. (Image credit: NOAA/ WPC)

\With just five days to go before September kicks off, it’s not surprising that a series of tropical waves are in the weather news this week. The question is what, if any, effect they may have on Florida’s weather over the Labor Day weekend — and perhaps longer-term.

On Monday, the National Hurricane Center predicted no tropical development through at least Friday. But a series of tropical waves are now marching across the Central Atlantic, and one of them is set to arrive in the vicinity of South Florida on Saturday.

A weaker wave was forecast to slide across South Florida Monday, increasing rain chances across the peninsula’s Atlantic Coast in the morning and then spreading toward the Gulf Coast in the afternoon.

Forecast models have been mostly cool to the idea of any ramping up of the wave expected over the weekend. Still, National Weather Service forecasters in Miami have ticked up precipitation chances next weekend into the 50-60 percent range.

“The combination of deep tropical moisture and stronger easterly flow is often ripe for locally heavy rainfall across South Florida,” forecasters said in their Monday forecast discussion, but NOAA’s Weather Prediction Center shows subdued seven-day rainfall totals around the Florida peninsula with perhaps some heavier showers in the Keys.

Two Atlantic waves were highlighted in the NHC’s tropical analysis Monday, one a system near 60W that “appears to have become more defined at the surface and low levels.” Another wave right behind it “is surrounded by a rather stable and dry environment,” forecasters said. Only isolated showers were associated with the disturbance.

Forecast models have been suggesting some awakening in the Atlantic, but no threats to coastal areas.

Still, with the statistical peak of the hurricane season now just 15 days away, forecasters are watching all of these systems closely.

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RECORD WATCH: The low in Key West Sunday was 85, which tied a record warm low for the date set in 2009.

Tampa swamps 79-year-old rainfall record; recalling Katrina

Hurricane Katrina anniversary

This weekend was the 13th anniversary of Hurricane Katrina’s landfall in South Florida. After forming in the Bahamas, Katrina became a hurricane shortly before smacking the peninsula  between Hallandale Beach and Aventura on August 25, then muscling up in the Gulf of Mexico after a short trip across the Everglades. The Keys were hammered, with the Dry Tortugas recording winds gusts of 105 mph as Katrina began its fateful trip to the northern Gulf Coast. (Image credit: NWS-Key West)

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Tampa beat a 79-year-old rainfall record Saturday with 2.45 inches, topping the old mark of 2.17 inches set back in 1939.

A CoCoRaHS observer in Citrus Springs in Citrus County reported 3.62 inches. The National Weather Service said 2.07 inches fell in Fort Myers.

In South Florida, an observer west of Hollywood in Broward County measured 2.24 inches, but many coastal areas received just a trace of rain, or no rain.

On Friday, Tallahassee set a rainfall record with 2.68 inches, breaking the old record of 2.11 inches set in 2008.

TROPICS WATCH: The National Hurricane Center said no tropical systems were expected for form in the Atlantic over the next five days, which would complete the month of August with no threats to the U.S. Coast. Forecast models showed a few systems trying to spin up over the next 10 days, but they were fizzling from run-to-run.

Regarding the tropical wave expected to impact the Florida peninsula on Labor Day Weekend, the National Weather Service in Miami had this to say on Sunday:

“The GFS and ECMWF have some modest differences regarding the timing and strength of the tropical wave forecast to slide westward along the base of the ridge and across the peninsula late week. However, no reliable long-range models currently show significant development beyond a strong wave.

“Regardless of the exact timing, this feature looks to be associated with a marked increase in tropical moisture and breezy east-southeast flow. Little change in the forecast for this period from previous runs, with the forecast still for a relatively wet end of the week into the weekend with numerous showers and storms across South Florida.”

But in Melbourne, NWS forecasters said model trends suggest a weakening wave. “Potential increase in rain chances looks a little dubious at the moment,” they said.

NOAA’s Weather Prediction Center indicates Florida rainfall through next weekend will be focused on the West Coast and into the Gulf of Mexico.

In the Central Pacific, Tropical Storm Lane dumped as much as 45.80 inches of rain on Hawaii as it stalled off-shore as a weakening system, according to Weather Underground. It was expected to be downgraded to a tropical depression on Sunday.

RECORD WATCH: The low in Key West Saturday was 85, which broke the record warm low for the date set in 2015.

 

Focus on tropics as peak of season nears; weighing winter forecasts

It’s almost September, the time of the year to look at tropical waves more closely for signs of development. A system that may approach the state next weekend is getting some attention.

The National Hurricane Center Tropical Weather Outlook map predicts clear sailing for the next five days in the Atlantic. The Canadian forecast model (CMC), is not exactly the gold standard when it comes to tropical weather prediction. Nonetheless, it has been consistent over the last couple of days in showing a system in the vicinity of the Florida peninsula spinning up late in the week.

Friday runs were taking the low through the Keys or across northern Cuba, then into the Gulf of Mexico. Saturday runs were keeping it east of the Bahamas and then drilling into the Carolinas on Labor Day.

It’s something to keep an eye on as the final week of August unfolds.

The National Weather Service in Melbourne had this to say on Saturday: “Both the ECM/GFS show a tropical wave approaching the Bahamas Friday and south Florida by Saturday, which would portend increasing rain chances.

“Given the rather hostile MDR (Main Development Region of the tropical Atlantic) conditions thus far in 2018, model guidance has been somewhat less than stellar in it accuracy/continuity with strength/position of waves within and emanating from the MDR thus far in August, so the standard caveats apply for day 7-8 forecasts being prone to changes w/r/t synoptic features.

“Nevertheless this is the first wave of the season that the model guidance has shown approaching the state with any sort of amplitude, which shows that September is almost here.”

HOPE FOR HAWAII: Lane was downgraded to a tropical storm late Friday, but parts of the Hawaiian Island were dealing with “epic rainfall,” the Honolulu Star Advertiser said, with amounts of up to 30 inches.

But the consensus seemed to be that the islands had dodged a bullet in terms of wind damage. As it was making its anticipated turn to the west, away from Hawaii, winds maxed out at 65 mph after the storm was knocked around by wind shear.

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HOT AND COLD RUNNING FORECASTS: The upcoming winter will bring “teeth-chattering cold” to the North with plenty of snow, with normal temperatures and wet weather in the Southeast, according to the newly-issued “sneak peek” Farmers’ Almanac forecast. It was released under the headline: “Frosty Forecast Melts Rumors of Mild Winter.”

The publication says: “So just how cold will it be? The real teeth-chattering arrives mid-February especially in the following zones: Northeast/New England, Great Lakes, Ohio Valley, Midwest, and Southeast (yes, even the Southeast will be in the chill zone!).”

It’s a bit at odds with what normally happens during an El Niño winter.

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Typical impacts on North America during an El Niño winter. (Image credit: NOAA)

NOAA says there’s a 70 percent chance of an El Niño for the upcomng winter, and that usually means warmer than normal temps across the northern tier of states, with drier weather from the Mississippi River east to the Applachians but wet conditions across the South, including Florida.

The book on Florida during an El Niño winter is wet conditions through the peninsula and abnormally cool temperatures, the Florida Climate Center at Florida State University says.

But the “cool” part of the forecast is because El Niño usually brings more cloudy weather to the state, not because Florida is more vulnerable to Arctic cold fronts.

Central Florida often suffers through multiple tornado events. Some of the worst outbreaks in the state’s history have occurred during El Niño winters.

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The chart looks at general trends in Florida weather during El Niño, La Nina and neutral conditions in the Pacific. (Credit: Florida Climate Center)

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RECORD WATCH: Gainesville set a rainfall record Friday with 3.73 inches. That beat the old record for the date of 3.45 inches set in 1993. Tallahassee reporded 2.68 inches Friday, also a record for the date. The previous mark was 2.11 inches set in 2008.

Debby transitions to tropical storm, but is expected to dissipate by Friday

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Debby transitioned into a tropical storm from a subtropical storm on Wednesday, but forecasters said the system would begin breaking down by Thursday morning and become post-tropical by Thursday night. The system should dissipate by Friday, they said. (Image credit: NHC)

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SNEAK PEEK: The Farmer’s Almanac posted Wednesday: “Labor Day already? It’s hard to believe, but summer is winding down.”

It’s actually three weeks from Monday. The Almanac’s forecast calls for rain in Florida and much of the southeast, and Accuweather is calling for thunderstorms in Miami, Orlando and Tampa.

Leading up to the holiday, NOAA’s Climate Prediction Center four-week forecast is for heavier than normal rainfall in all of Florida from the panhandle down to the Keys. The agency is also predicting below normal temperatures, but we’ll believe that when we see it.