Tropical Depression Nine Dissipates But Still Need to Watch

Tropical Depression Nine Dissipated Wednesday night as it moved over the Yucatan Peninsula. While still expected to bring soaking rains to that area (5″-10″+), the disturbance no longer looks organized enough to be considered a depression. In fact, a look at the enhanced satellite imagery from Thursday morning doesn’t show much over the Yucatan. Rather the heavy thunderstorm activity moving into the western Caribbean is far removed from the actual broad area of low pressure, which is still over the Yucatan.

Floater IR Enhanced

Despite having dissipated, we will still have to watch the remnants of TD9 once it emerges into the western Caribbean. Over the last few days, models have been trying to develop the remnants into something that would move into the Gulf. However, today, all of those models have backed off and no longer show any development. Below are the ECMWF (Euro) and the GFS; note neither shows any re-development of TD9.

ECMWF vs GFS MSLP and Precip Rate

As for one of the reasons why re-development is unlikely, we have to focus in on precipitable water values which measures the amount of available moisture in the atmosphere. As we head into the weekend, a big trough will help to drag dry air through the Gulf and into the western Caribbean. Notice the abnormally dry air (denoted by shades of yellow and brown) by the weekend sitting in the Gulf.

Precipitable Water

That same trough will bring higher wind shear into the picture through the weekend and into early next week. This will produce a very unfavorable environment for development or re-development in the Caribbean.

GFS Wind Shear

In addition, sea surface temperatures in the Caribbean are actually at or slightly below average for this time of the year. Having said that, if anything did spin up into the Gulf next week, SST’s are running well above average and would provide plenty of fuel for development.

sst_anom_avhrr_amsr_carib

 

Tropical Depression 9 to Soak the Yucatan; Uncertain Long-range Forecast

Tropical Depression 9 maintains strength in the Bay of Campeche Wednesday morning as it slowly drifts eastward. The structure of the tropical depression is still disorganized due to moderate westerly shear and dry air over the central Gulf. However, Hurricane Hunters continue to find a well-defined center of circulation. If enough convection organizes near its center Tropical Storm Hanna could form briefly by tonight before it moves over the Yucatan Thursday. Notice the deepest convection on enhanced satellite imagery is not associated directly with Tropical Depression 9. A huge slug of tropical moisture nears western Cuba and south Florida through the end of the work week and dumps heavy rain on the region.

Floater IR Enhanced

Future Tropical Storm Hanna is set to dump 5-10 inches of rain (isolated areas will see up to 15 inches) on the Yucatan peninsula in the coming days. The storm will obviously be disrupted by land interaction (should briefly dissipate) through Friday. Whatever is left of Tropical Depression 9 will interact with a trough through the weekend and possibly into next week over the western Caribbean. While wind shear values will be somewhat lower atmospheric conditions aren’t perfect for tropical cyclone development. The graphic below is the 11 AM advisory.

TD 9

Parts of south Florida catches a break from Tuesday’s flooding rains early Wednesday. More downpours drench the Keys and will affect Southeast Florida too through early Saturday. This moisture is not directly associated with Tropical Depression 9. The Weather Prediction Center estimates up to 3.5″ is possible near or just south of the Florida Keys by Saturday morning.

Florida Satellite-Radar Weekend AM

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The long-range forecast for Tropical Depression 9 is especially complicated. Recent computer models suggest that while a “piece” of the storm will be carried towards the Bahamas and out to sea over the weekend (as a trough lifts out of the Caribbean ) a greater “piece” of energy could linger in the western Caribbean. Computer models are split between a meandering broad low in this region into mid-week next week and a stronger tropical low lifting north towards Cuba and possibly Florida. The graphic below is the 12Z model run through Tuesday night.

Invest 93L Models

It’s early but it appears the reliable ECMWF model wins the battle of the models so far. The 0Z run suggests a broad low lingers in the western Caribbean through next work week under the influence of strong high pressure over the Southeast U.S. The GFS model has been back and forth. The 12Z run is more in line with the Euro and keeps pressure generally low in the western Caribbean through mid-week next week. Interest in the Caribbean and south Florida should monitor the progress of TD 9 in the coming days.

Euro vs GFS

 

 

Tropical Depression 9 forms

TD # 9 has formed in the Bay of Campeche. It is still disorganized, and it moving to the east very slowly.ir_enhanced_storm1_1 Before it moves onshore, it could become Tropical Storm Hanna. The short term forecast is simple, but the log term becomes more complicated. As it moves into the Western Caribbean, a piece of it may be left behind.trackmap_storm1 So keep it right here for the very latest.

Invest 93L Attempts to Organize Near the Yucatan Peninsula; Extended Wet Period for South Florida

Invest 93L attempts to organize as it near the Yucatan peninsula Tuesday. The odds of development per the NHC sit at 50% by Thursday afternoon and 50% over the next five days. Hurricane Reconnaissance Aircraft found a small well defined center this afternoon but convection isn’t organized enough for Invest 93L to be upgraded to a tropical cyclone. Moderate westerly shear pushes the deepest convection towards the Yucatan but a huge slug of tropical moisture brings pockets of heavy rainfall up towards south Florida (especially over the Keys). Models generally bring Invest 93L east-northeast in the coming days. The question remains if the area of low pressure lingers in the northwest Caribbean for a while or it gets picked up by a trough and carried out to the open western Atlantic this weekend. The bottom line is regardless of development an extended wet periods is expected for the Yucatan, Cuba, and south Florida.

Fly to Gulf Disturbance

Invest 93L Models

The GFS model brings 7+ inches of rainfall to Key West and about 6″ to Miami by Saturday afternoon. These totals may be a little overdone as recent model runs keep Invest 93L further south. The Weather Prediction Center estimates t 5+” is possible in Key West by next Tuesday in their 7 day outlook. Areas south of Tampa Bay will also see enhanced rainfall but the hefty totals stay south of Ft Myers. The further south Invest 93L stays the less rainfall south Florida will see.

GFS-Precip Acc

The 0Z ECMWF and 06Z GFS are in pretty good agreement through Friday. Deep moisture brings steady rainfall to south Florida and west Cuba into Friday afternoon. The area of low pressure stays weak/possibly just broad in nature near the Florida Straits and northwest Cuba. With a stalled frontal boundary nearby enhanced wind shear will make it tough for Invest 93L to deepen significantly.

ECMWF vs GFS MSLP and Precip Rate

Tropical moisture looks to exit south Florida early Saturday. By early Sunday morning both the 0Z ECMWF and the 06Z GFS track low pressure northeast into the open western Atlantic. The Euro does keep a small “piece” of low pressure behind in the western Caribbean. If this is valid tropical downpours could linger in the western Caribbean into next work week.

ECMWF vs GFS MSLP and Precip Rate.png 2

 

 

 

 

Watching the Gulf for Potential Development

The models have continued to hint at the potential development of an area of low pressure in the southwest Gulf for the last couple of weeks. However, there is very little run to run consistency and hence, plenty of uncertainty with this scenario. A look at the enhanced satellite picture shows a disorganized area of showers and storms in the Bay of Campeche. These showers are being fueled at least partially by the leftovers of Trudy, which made landfall on the Pacific coast of Mexico earlier this weekend.

Floater IR Enhanced 2

The National Hurricane Center gives this area a low chance (10%) of developing by Tuesday evening, but a higher chance of slowly developing by later in the week as it traverses eastward. After this disturbance begins to move eastward, that’s where the models differ on their respective solutions. The ECMWF (Euro) has a deep trough that digs into the Gulf and develops this system just west of Florida, eventually taking it up through the Peninsula early next weekend. While this scenario is certainly possible, it would likely be some sort of hybrid system and not fully tropical. Another caveat is that the Euro ensembles are farther east with their development of this system, impacting South Florida instead of the Big Bend.

ecmwf_car_018

Meanwhile, the GFS model is more in line with the Euro ensembles. It develops this hybrid system across the Florida Straits and brings it up through extreme southern Florida before curving out to sea. Many of the other models we look at fall somewhere between these two solutions. With this much uncertainty, anything is possible but the forecast is far from set in stone. Be sure to check back here throughout the week for the latest.

GFS MSL and Precip Rate

 

Gonzalo Continues to Strengthen; Ana Still Eyes Hawaii

After dropping back to a Category 3 strength storm Wednesday night, Gonzalo has re-strengthened into a strong Category 4 storm. Maximum sustained winds as of 11am Thursday were at 145mph and the minimum central pressure was down to 940mb. The storm exhibited an impressive-looking eye structure after completing an eyewall replacement cycle Wednesday night. The satellite picture showed a very symmetrical looking storm with a classic convective structure.

Florida Visible-Tropical Moisture

Sea surface temperatures are fairly warm under Gonzalo, which has allowed it to maintain intensity (and even strengthen). Those sea surface temperatures will start to drop off a bit as the storm approaches Bermuda, but will still likely remain warm enough to support major hurricane intensity. In addition, the wind shear is favorable for the intensity of the storm. An analysis of the wind shear below (courtesy University of Wisconsin) shows Gonzalo in an area of 15kt northwesterly shear, which is moderate. However, the wind shear at the mid-levels of the atmosphere (second image below) is much lower, closer to 5kts or so and is likely helping to intensify Gonzalo.

Upper Wind Shear

Mid level shear

In addition to the lower mid-level shear, the shear tendency downstream of Gonzalo is favorable for a storm of this intensity (image via University of Wisconsin). Shear tendency measures the pattern of wind shear over the last 24 hours (lessened or strengthened) and shows Gonzalo moving into an environment that has seen the wind shear decrease by 5kts in the last 24 hours. At the same time though, notice how wind shear has increased over Bermuda, as well as over the Eastern seaboard (thanks to a frontal system). Therefore, while conditions will remain favorable for Gonzalo in the short term, beyond 24-36 hours the shear should increase significantly enough (and the sea surface temperatures should cool down enough) to allow Gonzalo to weaken.

Shear Tendency

While it is increasingly evident at this point that Gonzalo will be a major hurricane as it passes near Bermuda, the key for the island will be the exact track. The current forecast calls for the storm to pass just 20 nautical miles to the west of Bermuda, putting the island on the dangerous east side of the storm and well within striking distance of the powerful winds in the eyewall. However, just a slight shift west or east in track would make a huge difference.

Gonzalo Wide Trackpng

Gonzalo Close Up Track

There are several major effects that a storm track like this would have on Bermuda. First and foremost, winds will be intense. Hurricane force winds extend outward up to 45 miles from the eye of Gonzalo, and tropical storm force winds extend outward up to 150 miles. The latest advisory from the NHC gives Bermuda a 74% chance of seeing hurricane force winds from Gonzalo and this number may go up as we get closer to these potential effects. Tropical storm force winds will likely begin by Friday morning, and will intensify to hurricane force by Friday afternoon/evening as the storm passes by the island.

Wind Radii 1

Wind Radii 2

Another effect from Gonzalo will be wave heights and storm surge. On the eastern side of the storm, Bermuda will experience the worse of the storm surge. Elsewhere, high wave heights will be a big issue. Maximum wave heights from the storm may approach 50 feet in areas, and even the East Coast of the US will see increased swells and a higher rip current risk.

Max Wave Heights

The final impact will be significant rainfall. With Gonzalo moving fairly slowly at the moment, rainfall amounts on Bermuda may be 3″-6″+. The latest run of the 12km RPM model shows upward of 6″ of rain across the entire island by Friday night.

RPM 12km Futurecast-Precip Acc Bermuda

With most of the attention on Gonzalo, we can’t lose sight of another dangerous storm, Ana in the Central Pacific. As of 11am Thursday, Ana was a tropical storm with maximum sustained winds of 60mph. Ana has suffered from higher wind shear over the last couple days. However, the latest enhanced satellite imagery shows a slightly improved structure to Ana, along with some deeper convection near the center.

Ana Enhanced Satellite

The official track for Ana takes it to the northwest, eventually curving it just southwest of the Big Island as a Category 1 storm Friday night. It then recurves it back toward the islands, taking it very close to Oahu, Kauai, and Niihau. This would be the 3rd tropical storm this season to come close to or impact the Islands (Iselle and Julio). It is important to note, however, that track errors for storms in the East and Central Pacific is much higher than for those in the Atlantic.

Tropical Track Pacific

Gonzalo Now A Category 4-Aims For Bermuda; Ana Almost A Hurricane-To Impact Hawaii

It’s official. Hurricane Gonzalo becomes the first category four hurricane in the Atlantic since Hurricane Ophelia in 2011. As of 11 AM EDT max sustained winds reach 130 mph, pressure is down to 949 mph, and Gonzalo tracks northwest at 12 mph. The eye structure is better visible on enhanced satellite imagery in recent hours (likely due to the completion of an eye wall replacement cycle early this morning). Recon data estimates the inner eye is only 2 NM wide, a sign of a very strong hurricane. The major hurricane could fluctuate in strength over the next 24 hours, which is often the case with a storm of this magnitude. A Hurricane Watch is in effect for Bermuda and will likely be upgraded to a Hurricane Warning this afternoon. Bermuda still recovered from last weekends direct hit from Tropical Storm Fay. Swells will reach the island Thursday and the risk for rip currents increases at Southeast U.S. beaches. Tropical storm force winds reach Bermuda late Thursday and possible major hurricane force winds arrive early Friday. Gonzalo will dissipate near the Canadian Maritimes this weekend.

Floater IR Enhanced

As of the 11 AM advisory the center of Gonzalo will pass just west of Bermuda Friday morning. Any slight wobble will play a huge role in the extent of strong winds over Bermuda Friday. The field of hurricane force winds now extends out 35 miles for the center of Gonzalo. Tropical storm force winds extend up to 115 miles from its center. Bermuda also braces for significant storm surge and heavy rain.

Gonzalo 2

TD 6

Computer models stopped running data on Invest 91L Tuesday afternoon. The broad low combats hostile upper level winds and the odds of tropical depression development are low. It tracks northward in the open Atlantic in the coming days.

Invest 91L

Tropical Storm Ana has its eye set on Hawaii this weekend and a Hurricane Watch may be issued soon. As of 11 AM EDT the center is now 675 miles from Hilo on the Big Island. It nears hurricane strength with winds of 70 mph. A west movement become more northwest Thursday into Friday. Swells will reach the Big Island Thursday and hurricane force winds are possible Saturday morning. The G-IV aircraft will assess the environment between Hawaii and Ana. This will give us valuable information as Ana needs the island state in a few days. Increasing wind shear near a trough near Hawaii’s western islands will cause at least some weakening.

ANA

The GFS model paints 3-7+” over the Big Island through the weekend (the heaviest on the less populated western side closest to the center of Ana. Honolulu could see a few inches of rain too.

GFS-Precip Acc

It’s a week away but worth noting. The reliable ECMWF model spins up an area of low pressure in the west-central Gulf of Mexico early next work week. The graphic below is paused Wednesday at 5 PM. The 12Z GFS also hints at pressure lowering the western Gulf this weekend. This makes sense with climatology in mid October.  Stay tuned.

ECMWF MSLP and Precip Rate

 

Gonzalo Becomes 2nd Major Hurricane of 2014-Eyes Bermuda; Watching Ana in Central Pacific-Could Threaten Hawaii

Hurricane Gonzalo becomes the second major hurricane of the 2014 Atlantic hurricane season Tuesday. At 5 PM EDT max sustained winds top out at 115 mph, pressure is down to a low 970 mb and it accelerates northwestward at 15 mph away from Puerto Rico and the Virgin Islands. The eye of Gonzalo is much more distinct Tuesday afternoon and cloud tops continue to cool. Major Hurricane Gonzalo could become the strongest hurricane of 2014 in the Atlantic Basin. It could reach category 4 strength Wednesday afternoon. Gonzalo will pass well east of the Bahamas and Turks and Caicos (and the U.S. thanks to a strong cold front)  but is a significant threat to Bermuda on Friday. It could still maintain major hurricane strength during this time too.

The only silver lining for Bermuda is the span of hurricane force winds is quite small. As of 5 PM hurricane force winds extend up to 25 miles from the center but the tropical storm force winds extend out up to 115 miles. Any slight wobble west or east could keep the strongest winds (possible major hurricane force) away from the tiny island. Nonetheless squalls and a period of flooding rains is likely for Bermuda during a period of time late in the day Friday. This forecast is subject to change.

Floater IR Enhanced

TD 6

Elsewhere in the Atlantic a disorganized Invest 91L churns between the Lesser Antilles and Africa. It is no threat to land and the odds of tropical depression development are low as it drifts northward over the open Atlantic.

Invest 91L

All eyes are on a strengthening Tropical Storm Ana in the central Pacific. It could become a hurricane late work week over warm waters and moderate wind shear. Ana rides the perimeter of a ridge in the Pacific and will track very close the Big Island of Hawaii late in the day Saturday EDT. This could be the second time this area in Hawaii sees tropical storm force winds in Hawaii this year (very rare).

Tropical Track Pacific

 

Hurricane Gonzalo Continues to Strengthen

Hurricane Gonzalo continued to look more and more organized on Monday, with plenty of convection around a low level center of circulation. The cloud pattern is becoming more symmetric and inner-core features are becoming evident on the enhanced satellite. Even the radar loop from San Juan shows a eyewall feature.

Floater IR Enhanced 2

Gonzalo_13Oct14_JUAlong

With warm waters and low wind shear ahead of it, Gonzalo is likely to continue strengthening. As of 11pm Monday night, maximum sustained winds were 85mph with a minimum central pressure of 984mb and the storm was moving to the NW at 12mph. Hurricane warnings were up for the British Virgin Islands, St. Martin, and Anguilla, with Tropical Storm Warnings active for Puerto Rico and the US Virgin Islands among others.

HURRICANE GONZALO1

The storm is expected to begin to curve more to the north and eventually the north-northeast over the next few days. With those warm waters and low wind shear though, it is forecasted to become a major hurricane by Wednesday and will be on a path very close to Bermuda by the end of the week. Interests in that area should pay close attention to any changes in the storm’s intensity and track.

HURRICANE GONZALO2

Gonzalo isn’t the only storm we’re concerned about. In the Central Pacific, Tropical Storm Ana has formed southeast of Hawaii. The forecast calls for Ana to become a hurricane in the coming days, and take a dangerously close track toward the Big Island, which was already hit by a tropical storm earlier in the season. We’ll have to continue to watch Ana closely in the coming days.

TS ANA

 

 

Fay Becomes Hurricane Before Weakening; Gonzalo Forms and Threatens Puerto Rico

Fay became the fifth hurricane of the 2014 Atlantic Hurricane Season on Sunday as it brushed by Bermuda. The storm was picking up speed as of Sunday night and weakened by 11pm to a tropical storm with winds of 65mph. It is moving to the ENE at 25 mph and will continue out into the open Atlantic before being absorbed by a frontal system by Monday afternoon.

FAY TRACK

Meanwhile, in the eastern Caribbean, Invest 90L has become the 7th named storm of the season, Tropical Storm Gonzalo. The storm exhibits some low-level circulation and thunderstorm activity around a primitive eye feature and continues to become more and more impressive looking Sunday night. The location of the storm as of Sunday night was less than 100 miles east of the Lesser Antilles and its movement was to the west at about 12 mph.

Enhanced Satellite

Gonzalo is expected to strengthen over the coming days due to favorable environmental conditions. Sea surface temperatures are generally in the mid 80s, which are 0.5°-1.5° above average for this time of the year. Meanwhile, wind shear is expected to remain fairly low in the vicinity of Gonzalo through the middle of the week.

SST Anomalies

GFS Wind Shear

With these environmental conditions in place, Gonzalo will likely become a hurricane in the coming days. However, the intensity beyond that is still up in the air, with some models intensifying the storm much more than others. The official NHC forecast calls for Gonzalo to become a strong category 2 hurricane by Wednesday or Thursday. As far as the track goes, most of the models are in fairly good agreement that Gonzalo will continue off to the west before a frontal system lifts it north and eventually northeast for the middle of the week (timing differences do exist). Along that path, Gonzalo will impact the northern Lesser Antilles, Virgin Islands, and Puerto Rico. Therefore, Tropical Storm Warnings are up in those areas, with a Hurricane Watch up for the US and British Virgin Islands and Puerto Rico. Interests in those areas should heed warning and pay close attention to any changing details in the forecast over the next 24 hours.

Gonzalo Track plus spaghetti