Atlantic Tropical Weather 2010: 17th Storm Forms In Caribbean

Tropical Storm Richard has formed in the western Caribbean, between Honduras and Jamaica.  T.S. Richard is the 17th named storm of the 2010 Atlantic season.

Tropical Storm Richard is projected to strengthen to hurricane strength within the next 2 days.  As this happens, he is expected to move toward the west.  After Saturday, then-Hurricane Richard should curve toward the northwest.  He could possibly make landfall along the Yucatan Peninsula Sunday or Monday.  Three model solutions have this track.  Alternatively, he could make a turn more toward due north and pass between the Yucatan and Cuba on his way into the Gulf of Mexico.  Two other models have this solution.  As local ridges and troughs move and pass by, Richard could make his way across the entire Gulf of Mexico.  The potential for a U.S. mainland landfall sometime next week cannot at this time be ruled out.

As usual, intensity and track forecasts out past 3 days are notoriously error-prone.  A lot of things can happen in that time frame.  The best thing to do is be aware this storm has formed and keep an eye on his progress over the next handful of days.

Atlantic Tropical Weather – 7/22/2010: Tropical Storm Bonnie & Tropical Depression #3

[Updated post]:

Tropical Storm Bonnie has formed in the Atlantic basin this afternoon.  Surface winds are now a sustained 40mph and the system is organizing itself more and more every hour.

T.S. Bonnie’s center is located near 22.7N, 75.4W; has maximum sustained winds fo 40mph; is moving NW @ 13mph and has a central pressure of 1006mb.

Bonnie has deep convection near the west side of her center.  Outflow is looking better in most quadrants.  She is still battling a strong upper-level low to her west, which has kept high vertical wind shear and dry air near Bonnie.  The storm’s center moved around during the day, resulting in some adjustment to the specific location of her probably future track.  The direction of her track will likely remain toward the NW/WNW, but is somewhat further north than it was earlier today.  As a result, Bonnie could pass closer to mainland Florida tomorrow afternoon before entering the Gulf of Mexico.  The official track still calls for a likely landfall near LA later this weekend (Sunday or later).

[Original post]:

Atlantic Basin Tropical Depression #3 has formed between the Bahamas and Cuba today.  The tropical wave that eventually developed a closed surface circulation has been moving across the Atlantic basin this week.  Heavy bursts of intense convection occurred the past three days as the wave passed along the northern Caribbean islands.

Given local weather features, T.D. 3 should intensify into a Tropical Storm later today but not intensify into a hurricane before making landfall somewhere along the U.S. Gulf coast (next week?).

T.D. 3′s center is located near 21.9N, 75.0W; has maximum sustained winds of 35mph (just below T.S. strength); is moving WNW @ 14mph and has a central pressure of 1008mb.

T.D. 3 will move through the Florida Strait (between FL & Cuba), likely right over the Florida Keys, entering the Gulf of Mexico tomorrow.  Thereafter, forecast models project a track envelope extending from southwest of Houston to south of New Orleans (~3 days from now).  The official track forecast from the National Hurricane Center shows the storm making landfall closer to the Lake Charles area.  While T.D. 3 (then T.S. Bonnie) won’t be a monster storm like Katrina or Rita, the projected tracks take the storm very close to the site of the Gulf Oil Disaster.  Work near the disaster site has been halted while officials confer on what the course of action should be as the storm evolves.

An Air Force Reserve hurricane hunter is on its way to the storm to gather additional data.  We will know later today whether T.D. 3 has intensified to T.D. Bonnie or not.

Atlantic Tropical Weather – 6/29/2010: Tropical Storm Alex

Tropical Storm Alex has pulled away from the Yucatan Peninsula and the shallow Gulf of Mexico quickly today.  He hasn’t strengthened to hurricane status quite yet, but is close to doing so.  At this point, it is unlikely that he will strengthen to major hurricane status prior to landfall.

T.S. Alex’s current position is 22.9N, 93.6W; is moving NW @ 13mph; has sustained winds of 70mph; has a central pressure of 981mb, which is low for a Tropical Storm.

T.S. Alex should continue to turn more westerly through the next couple of days.  His official track forecast brings him ashore along the Mexican coast, though the specific landfall keeps moving north with successive model forecasts.

T.S. Alex should keep strengthening over the next day, prior to landfall, making hurricane strength later today but not quite getting to Category 2 status.  Thus, he should make landfall as a Category 1 hurricane somewhere in northeastern Mexico.

Storm surge is already impacting the Gulf coast of the U.S. with <3′ surge along the LA coast and increasing to 3-6′ surges further south along the TX coast.

6/28/10 post.

6/26/10 post.

6/25/10 post.

Atlantic Tropical Weather – 6/28/2010 #1: Tropical Storm Alex In Gulf of Mexico

Tropical Storm Alex moved fairly quickly over the Yucatan Peninsula this weekend, entering the Gulf of Mexico last night.  He also maintained his integrity very well while over land.  Banding features and central low development actually continued while transiting the peninsula.  Thus, T.D. Alex reintensified into T.S. Alex just prior to moving back over water.

T.S. Alex’s current position is 20.3N, 91.7W; his maximum sustained winds are 60mph; is moving NNW @ 6mph; and his central pressure is now 989mb.

The lowering central pressure and resulting increasing wind speeds indicate that Alex will continue to intensify as he moves over the warm Gulf waters and enjoys upper-level venting support.  Whereas forecasts last week had Alex remaining as a Tropical Storm until his eventual landfall, it now looks like Alex will strengthen into the 2010 season’s first hurricane.  If conditions remain favorable, Alex could even intensify into the season’s first major hurricane also (>= Category 3 strength).

T.S. Alex’s official track forecast over the next 3 days takes him on a gently arcing path through the southern Gulf of Mexico, potentially making landfall near the Mexico/Texas coast this Thursday.  After 3 days, the storm is projected to move near the Mexican/Texas border through Saturday.  There remains considerable division in model track solutions with some showing something akin to the official track forecast while others show a marked turn to the north as the storm approaches land.  At this time, the only effect that has is to shift the point of landfall further north along the Texas coast.

T.S. Alex’s official intensity forecast calls for a Category 1 storm to form by tomorrow morning and a Category 2 storm by Wednesday morning.  He is projected to make landfall as a hurricane Thursday morning.  Interestingly, it looks as though most intensity models show Alex strengthening to just below hurricane strength.  The official forecast relies more on models that have performed the best in past years.

Alex’s growing windfield will begin impacting the Gulf oil disaster in the next couple of days.  Winds will turn easterly and increase in strength, even though Alex is hundreds of miles away from the disaster site itself.  This will have the effect of pushing oily water back into the coasts of LA/MS/AL.

Atlantic Tropical Weather – 6/26/2010: Tropical Storm Alex Forms

As of 5A EDT this morning, the National Hurricane Center upgraded Tropical Depression One to Tropical Storm Alex.  A hurricane hunter aircraft found flight-level winds of 46kts and satellite-derived near-surface winds were estimated to be 35kts.  With those two indicators, and given the storm’s organization, the 2010 season’s first tropical storm has officially formed.

Alex’s center is currently located at 17.0N, 85.3W.  His maximum sustained winds are 40mph; moving WNW @ 8mph.  His central pressure is ~1004mb.

Not much has changed for T.S. Alex’s projected track or intensity for the next few days.  He is expected to continue moving WNW to NW over the next three days.  Given his current position – north of Honduras in the western Caribbean – this will take Alex over either Belize or the Yucatan Peninsula of Mexico.  While over land, Alex will weaken back into a Tropical Depression.  The official track forecast has Alex entering the Gulf of Mexico sometime Monday morning, then continuing more or less in the same direction through Wednesday.  Beyond that, the track guidance is still a little split, but a lot more of them keep Alex in the western Gulf than in the eastern Gulf than was the case yesterday.

Once Alex re-emerges over water, he should reintensify from a Tropical Depression back into a Tropical Storm.  Landfall could occur along the Mexican coast later in the week as a Tropical Storm.

In the meantime, Alex is dumping plenty of rain in Central America.  With inches of rain falling per hour in the heaviest rainbands, flash flooding will be the primary threat to residents there.

Atlantic Tropical Weather – 6/25/2010: First Tropical Depression?

Update:

Tropical Depression One has formed off the coast of Honduras in the western Caribbean Sea.  The Air Force Hurricane Hunter aircraft found a well-defined central circulation.  The system continues to get better organized by the hour with large rainbands extending hundreds of miles away from the center.  TD1 is still expected to move northwest across the Yucatan Peninsula and enter the Gulf of Mexico late Sunday the 27th.  Thereafter, the official National Hurricane Center track forecast splits the difference of the two model solutions discussed below and keeps the storm on a general north-westerly track through the Gulf.

Original Post:

A disturbance that has made its way across the entire Atlantic Ocean and Caribbean Sea has finally developed a surface circulation and has sustained thunderstorms around it.  Currently identified as Invest 93L, it could be designated Tropical Depression 1 of the 2010 Atlantic Hurricane Season.

Invest 93L’s center is currently located near 16.9N, 82.9W.  It is moving NW @ 5mph and has maximum winds of 35mph.  An Air Force Reserve Hurricane Recon plane was sent to the system earlier today to see if it is organized enough to be classified as a Tropical Depression.

Numerical model solutions differ on its future.  3 of them take the system over the Yucatan Peninsula and into the southern Gulf of Mexico over the weekend, then show the storm turning more westerly toward Mexico or southern Texas.  3 others also take the system over the Yucatan and into to Gulf, but then the storm moves north under influence from an upper-level trough projected to move across the eastern U.S. after this weekend.  The result is two storm tracks that are nearly exactly opposite each other.  Obviously, we will have to wait until the storm has moved over the Yucatan to have a better idea of its long-term path.  Once it clears the Peninsula, it should be a weak Tropical Depression again; models are projecting a re-intensification over the very warm Gulf waters.

2010 Atlantic Hurricane Season & Gulf of Mexico Loop Current

NOAA has issued their last pre-season projection for the 2010 Atlantic hurricane season.  In short, a very active season is possible.  Here are the highlights:

We estimate a 70% probability for each of the following ranges of activity this season:

14-23 Named Storms,

8-14 Hurricanes

3-7 Major Hurricanes

An ACE range of 155%-270% of the median.

The seasonal activity is expected to fall within these ranges in 7 out of 10 seasons with similar climate conditions and uncertainties to those expected this year. They do not represent the total possible ranges of activity seen in past similar years.

I like to see numbers in context.  I’ll start with the 14-23 named storms.  On average, 11 storms are named every year.  The most active Atlantic hurricane season on record was 2005 – the same year of Katrina, Rita and Wilma – when there were 31 named storms.  The first storm formed on the 8th of June and the last storm dissipated on the 6th of January, 2006!   For those unfamiliar with hurricane naming conventions in the Atlantic, see this page.  The set available this year are the same as those used in 2004.  So if there are 14 named storms, Nicole will be the last of 2010.  If there are 23, then just like 2005, the list of names will be exhausted.  In 2005, storms after Wima were assigned Greek alphabet names.  That convention could be used again this year if things get really ramped up.

There were 15 hurricanes in 2005.  So this season’s projection calls for fewer hurricanes (tropical storm systems that attain 74mph sustained winds) than 2005.  Last season, there were only 3 hurricanes.  2008 saw 8 hurricanes form – so this year could be more similar to that year.  The average number of hurricanes per year is 6.

3-7 major hurricanes – those are big numbers.  The average number of major hurricanes per year is 2.  A major hurricane is one that reaches Category 3 strength on the Saffir-Simpson hurricane scale.  Storms typically have a minimum of 111mph sustained winds.  Of those 8 hurricanes in 2008, 5 reached major hurricane status: Bertha, Gustav, Ike, Omar and Poloma.  Of the 15 hurricanes in 2005, 7 reached major hurricane strength.  The difference between 2005 and 2008 in terms of number of major storms then was only 2.  A lot of factors determine how strong hurricanes get.  So the difference between 2 major hurricanes and 3 is a lot more than just a number.

The ACE measurement is a relatively new one.  It is the Accumulated Cycle Energy, used to measure individual storms as well as entire tropical seasons.  The ACE is calculated by squaring the the estimated maximum sustained wind velocity of each cyclone with sustained winds over 35 knots (tropical storm strength) every six hours.  Those values are then added together over the life-cycle of the storm.  The ACE values for every year since 1851 has been calculated by Chris Landea at NOAA’s National Hurricane Center.  A projected ACE of 155%-270% of the median is obviously indicative of a very active season.

One of the factors that has a big influence on how strong tropical systems that enter the Gulf of Mexico can get is the position and strength of the Gulf Loop Current.  This is the same current being discussed in relation to the oil volcano currently erupting off the Louisiana coast.  The good news for the potential future spread of oil away from the Gulf of Mexico is an eddy has broken off the Loop Current.  Oil within the eddy will more likely stay in the Gulf rather than be transported out of it, as Dr. Jeff Masters explains in this blog post.  The last Loop eddy that broke off is still in the western Gulf off the coast of Mexico, having traveled 3-5km per day since it broke off the main current back in July 2009.

Unfortunately, what’s good for limiting the spread of oil can be bad for tropical systems entering the Gulf.  The eddy maintains very warm sea temperatures to great depths, making high energy available to passing storm systems.  Hurricane Katrina is a perfect example of this.  She crossed the Florida peninsula on 26Aug2005 with 75mph sustained winds.  One day later, as she passed north of the western side of Cuba, she had strengthened to 115mph winds (a Category 3).  She stayed at that strength for another day while she passed over the northern edge of the Loop Current.  Then, she encountered a loop eddy.  Four hours later, her sustained winds jumped from 115mph to 144mph, becoming a Category 4 storm.  12 hours later, her winds were 161mph, becoming a Category 5 storm.  16 hours later, they had rocketed all the way up to 173mph.  In just over half a day, Hurricane Katrina went from a weak Category 3 storm to a Category 5 monster – mostly because she passed directly over the warmest core of the Loop Current eddy.  Thankfully for the residents of the Gulf Coast, that eddy was still in the middle of the Gulf.  If it had been closer to land, Katrina would have been even stronger at landfall.  In fact, Hurricane Rita passed over that same eddy later in 2005, rapidly strengthening just like Katrina did.   Rita’s path took her over even more water before landfall than did Katrina’s.  Rita still caused Houston to be partially evacuated and did plenty of damage after landfall.

So conditions are prime for another above-average hurricane season.  Individual storms will of course form where they will and little can be confidently said about their potential impacts on the Caribbean or Mexico or the U.S.   Potentially dangerous storms can quickly come together with all of the conditions that presently exist.  2010 could be another infamous season.

Cross-posted at SquareState.

Record High Atlantic SSTs: Active Hurricane Season To Follow?

Sea surface temperatures across the tropical Atlantic Ocean were higher in March 2010 than any other time in the past 160 years – the UK’s Hadley Center has data going back to 1850.  When temperatures in this region are warmer than average, very active hurricane seasons usually occur.  There are some complex interactions between Atlantic SSTs and other phenomena across the globe, most notably El Niño, so the relationship isn’t exact or direct.  2005 was the last year Atlantic SSTs north of the equator were also significantly warmer than usual.

How much above average were SSTs?  1.26°C above average during March.  That might not sound like it’s too much warmer than usual until you realize the previous record, set back in 1969, was 1.06°C.  This year’s record handily beat that value.  For additional context, the temperatures observed in March are closer to what are normally observed around June.  Finally, the record tied with June 2005 as the biggest positive departure from average in the dataset.

Read on for a more detailed explanation of why this has happened.