Tenacious Nadine Strengthens Once Again
Nadine is a true fighter of a storm. Throughout her life she's been bullied by occasional areas of high wind shear and cool waters. Despite this, she has fought back after every weakening spell, including this morning, when after a brief fall to tropical storm status, Nadine ramped back up and reintensified to hurricane status. As of the latest advisory from the National Hurricane Center, Nadine currently has maximum 1 minute sustained winds of 75mph and a minimum central pressure of 988mb. She is a category 1 hurricane on the Saffir Simpson Scale. Nadine is currently located about 610 miles WSW of the Azores and is moving NNW at 14mph.
Forecast for Nadine
Nadine is currently in an area of moderate wind shear and marginal sea surface temperatures. For this reason, even though she has strengthened in these conditions before, I don't see much intensification in the future for her, though I think it is possible she may peak at around 85mph based on current trends and her upgrade to 70kts at the 18z ATCF update. I am expecting little change over the next 24 hours, with steady weakening after this time, and I still believe Nadine will become non tropical in 4-5 days as it moves over cool waters. Regarding track, Nadine should continue a NNW motion for the next 18-24 hours. After this time, through about 4 days out, Nadine will be in an area of weak steering currents, and as it has for much of its life, will meander around the open Atlantic with very little motion, with a possibility of the storm making a cyclonic loop as the NHC indicates. Finally, Nadine should get caught up in westerly winds generate by a developing baroclinic storm in the Atlantic and get forced E/ENE in the direction of the Azores as it loses tropical characteristics. The NHC hints that the storm will mostly go north of the Azores, but I feel Nadine will really get caught up in the westerlies as she weakens and the baroclinic storm strengthens, forcing her more east and closer to the central Azores in 6 days or so. It is too early to tell any specific impacts, but I do not expect anything significant at this point. Tropical Storm watches may be required for the Azores in a couple days as a precaution.
Figure 1: Official NHC forecast for Nadine. I believe a more south/east solution is likely, but the way Nadine's been anything is possible.
After developing only yesterday, Tropical Depression Norman has become post tropical over the Gulf of California according to the 18z ATCF update. Norman's center is currently located about 100 miles WNW of Los Mochis, MX, with maximum winds of 30mph and a minimum central pressure of 1007mb. Norman's remnant circulation should dissipate within the next day or so, but some heavy rainfall will continue over Texas. I find it interesting that Texas has been looking to the Atlantic to provide a beneficial rain making tropical system, but they ended up getting it from a little East Pac storm.
Figure 2: The remnant circulation of Norman, which should dissipate in the next 24 hours.
Jelawat Weakens, Will Brush Japan
After providing some pretty strong impacts on Okinawa yesterday, Typhoon Jelawat has continued to weaken and accelerate NE. Jelawat currently has maximum 1 minute sustained winds of 75kts according to the Joint Typhoon Warning Center. Jelawat should continue to weaken in very unfavorable conditions, and it will likely make a second landfall in Japan tonight. Impacts should be minimal as it will not be a long duration event. Japan is generally in a favorable position to avoid the worst of tropical cyclones, as storms that get that far up are usually weakening and accelerating, providing general protection for cities like Tokyo. Southern parts of the country and places like Okinawa are more vulnerable as storms can still be quite intense as they reach those areas.
Figure 3: Typhoon Jelawat, weakening and accelerating NE as it heads for landfall in Japan. The storm was once a Cat 5 monster, but unfavorable conditions have taken a toll on it.
Nothing on the Horizon
There are no areas being watched for development in the Atlantic by the NHC, and none of the reliable models have shown any consistent development in the next 10 days. I still believe we'll get 1-2 more storms this year, but it's not impossible that the end of Nadine will mean the end of the 2012 season.
Figure 4: 12z GFS, 312 hours. A sure sign the times are changing.
Thanks for reading, and enjoy the rest of your weekend!
Updated: 7:15 PM GMT on September 29, 2012
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Tracking Nadine, Norman, and Jelawat
It's been a while since I posted as there haven't been any major systems in the Atlantic in a while. Right now the only storm in the Atlantic is Hurricane Nadine. Nadine has been wandering the Atlantic since September 11, with one brief break during which the storm went non tropical. As if the latest advisory from the National Hurricane Center, Nadine has maximum 1 minute sustained winds of 75mph and a minimum central pressure of 988mb, making it a minimal hurricane on the Saffir Simpson Scale. It is currently located about 710 miles SW of the Azores and is moving NW at 8mph.
Forecast for Nadine
Nadine is currently over moderately warm waters and heading into an area of moderate shear. Significant changes in intensity are unlikely for the next 2-3 days. After this time it will begin to move over cooler waters and stronger shear, which should weaken it and possibly lead to its final, long overdue demise in 5-7 days. Regarding track, Nadine should move steadily NW for the next 2 days or so, followed by a turn to the east and a slowdown after that time. What happens beyond here is a bit unclear as by the end of the forecast period the storm should be weakening due to cool waters and strong shear. I will likely write another blog in the next couple days to clarify what may happen beyond 5 days for Nadine. As of right now, Nadine is no threat to land.
Figure 1: Official NHC forecast track of Nadine. If anything I would have the storm move a bit faster towards the end of the period as the NHC suggests they may show in later advisories.
Norman Weak, But Providing Some Rain
Tropical Storm Norman formed in the East Pacific this morning. It currently has maximum 1 minute sustained winds of 40mph and a minimum central pressure of 1002mb. Norman is currently located about 130 miles NE of Cabo San Lucas, MX, and is moving briskly north at 16mph, meaning the storm will make landfall tonight. Norman currently looks very poor on satellite and should only get worse as it interacts with land more. It should continue to track north after it moves inland and dissipate quickly. While no significant impacts are likely, some heavy rain is falling in Mexico and Texas and may cause localized flooding.
Figure 2: A weakening Tropical Storm Norman, with the remnants of Miriam also visible.
Jelawat Moves Into Okinawa
For the second time in less than a month, a major hurricane is bearing down on the island of Okinawa. This time it is Typhoon Jelawat, which at one point was a Category 5 storm. A recent eyewall replacement cycle and less favorable upper level conditions have weakened the storm to a Category 3 with 120mph winds as it spins 125 miles SW of Kadena AFB, Okinawa, and is moving NE at 12kts. The center of Jelawat will likely pass directly over the island tonight, providing significant impacts, though it shouldn't be anything the well built island can't handle. Beyond this time fairly rapid weakening is likely to continue, and Jelawat will likely be a weak to moderate tropical storm when it makes a second landfall near Tokyo, Japan, in about 2 days.
Figure 3: Typhoon Jelawat. The clouding eye and a recent microwave pass suggest another EWRC is beginning, though this one is unlikely to finish.
Atlantic Outlook For October
With the exception of Nadine, the Atlantic has been rather quiet this September. Cape Verde season is essentially over (though some models are developing a wave near the coast of Africa- more information on that later if necessary) and conditions across most of the basin are pretty unfavorable. The main area to watch this month will be the Caribbean, as very warm water temperatures there will allow for storms to spin up quickly, provided there is limited shear and dry air, which has been a rarity this year. I do expect at least one Caribbean development this month, probably in the October 15-20 timeframe, with the most likely track being something similar to Hurricane Wilma of 2005.
Figure 4: The Atlantic. Moisture is evident in the Caribbean and I expect this to translate into something later in October.
Thanks for reading, and enjoy your weekend!
Leslie and Michael Gone; TD 14 Forms; Sanba Strengthening
The tropics remain active as we remain near the peak of hurricane season. Officially we are on the other side of the peak now, and we should begin a slow but steady decline in number of storms until the season officially ends on November 30. The Atlantic has been very busy in the past couple of weeks, but it has calmed today as former Hurricane Leslie has been declared extratropical after a landfall on Newfoundland and former Major Hurricane Michael dissipated over the open waters of the Atlantic today.
Figure 1: The remains of Michael are clearly visible, as he is now just a convectionless swirl. This remnant low should continue to weaken and eventually dissipate altogether.
Tropical Depression 14 Forms
Taking the place of Leslie and Michael is Tropical Depression 14, which formed earlier today. As of the latest (5PM EDT) advisory from the National Hurricane Center, TD 14 is located about 1170 miles E of the Lesser Antilles and is moving NW at 12mph. TD 14 currently has maximum 1 minute sustained winds of 35mph and a minimum central pressure of 1006mb.
Forecast For TD 14
Tropical Depression 14 will be in a favorable environment of low shear for the next 3-4 days, so strengthening is likely during this time. It is likely TD 14 will become Tropical Storm Nadine tonight, and the NHC forecasts a peak intensity of 75mph in about 3 days, which would make the system a minimal hurricane. Due to the good structure of TD 14 and the very conducive environment for strengthening it has for the next few days, I think the NHC forecast is probably conservative as I am expecting a peak of 90-100mph on Friday or Saturday. After this time, wind shear will increase significantly over the storm and weaken it. TD 14 will likely be a typical recurving storm as it should continue to track NW, then NNW, then N, and eventually NE as the subtropical ridge over the Atlantic breaks down. TD 14 will not be a threat to the US or Bermuda, but interests in the Azores should keep an eye on the system as impacts there cannot be ruled out.
Figure 2: Tropical Depression 14, showing good overall structure but some convective disorganization.
Figure 3: Official NHC forecast for TD 14.
Elsewhere in the Atlantic it is mostly quiet with no invests and no areas currently being monitored for development by the NHC. The wave train continues off of Africa, and it is probable we will see at least another storm or two before Cape Verde season winds down towards the end of the month and our focus shifts closer to home in the Caribbean.
Invest 90E May Develop In East Pacific
The East Pacific came roaring out of the gate this year, producing storm after storm, but it has slowed significantly into the middle of the season and has not produced a major system in a while. There is currently one area of disturbed weather being watched out there, Invest 90E. 90E is a large disturbance that has been slowly consolidating, and it is being given a 70% chance of development in the next 48 hours by the NHC. There is also a Tropical Cyclone Formation Alert issued for it. The center of 90E is located well off the coast of Mexico, and it is moving WNW at about 10mph, meaning it is moving away from the coast and should not threaten land. I give 90E about a 60% chance of developing in the next 48 hours based on its large size and need for further consolidation, but a 90% chance of the disturbance developing at any point in its life.
Figure 4: Invest 90E
Sanba Strengthening, Targeting Koreas
After an extended dry spell, the West Pacific has roared to life once again as another potentially powerful storm is forming out there, Tropical Storm Sanba. As of the latest advisory from the Joint Typhoon Warning Center, Sanba has maximum 1 minute sustained winds of 50mph. It is located about 700 nautical miles east of Manila, Philippines, and is moving slowly NW at just 5kts.
Forecast For Sanba
Sanba has the potential to become a dangerous storm. It is over and will continue to be over extremely warm waters of up to 30C, and has favorable upper level conditions to work with. The official JTWC forecast indicates steady strengthening for the next 4 days with a peak of 100kts, or 115mph, which would make Sanba a major hurricane. In general, I agree with the forecast reasoning, but there is one problem that I see: In the time since the issuance of the advisory a few hours ago, Sanba has seemingly intensified quite quickly, with deep convection wrapping around the whole system and an eye forming. This eye is very evident in microwave imagery and can be seen on satellite, so it is likely Sanba is at around 60-65kts right now. If this trend of rapid intensification continues, the 24 hour intensity forecast calling for a 65kt hurricane may be off by as much as 20kts. This would potentially mean the listed intensities are too low, and the peak may be closer to 115-125kts as conditions appear favorable for this intensification to continue. The main steering feature for Sanba is a building subtropical ridge that will keep the storm on a fairly straight NW heading for much of the forecast period, with a more NNW turn likely in 5 days or so. This track brings the storm in the direction of southern Japan and the Korean Peninsula. Interests in these areas should monitor the progress of this storm very closely as it appears likely landfall will be made somewhere in that area in 5-6 days.
Figure 5: Official JTWC forecast track for Sanba.
Figure 6: Tropical Storm Sanba. An eye is apparent, and the storm is likely at or near typhoon intensity.
Figure 7: Microwave image of Sanba, with the eye very clear.
Thank you for reading, and have a great night!
Leslie Slowly Organizes; Michael Strengthens
Surprisingly for the beginning of September, the Atlantic is the only basin in the world with an active tropical cyclone, as the East Pacific lost John today and the West Pacific continues through an unusual calm spell for this time of year. The Atlantic actually has two storms being watched tonight, with the biggest threat being Tropical Storm Leslie. As of the latest (5PM) advisory from the National Hurricane Center, Leslie has maximum 1 minute sustained winds of 65mph and a minimum central pressure of 994mb. Leslie is currently located about 500 miles SSE of Bermuda and is creeping north at just 3mph.
Forecast for Leslie
Leslie's life so far has been dominated by shear, as convection has been repeatedly blown off the center, leaving it exposed. That has changed some today though, as an area of convection has been able to persist over the center. Despite this, Leslie remains in an area of moderate shear of about 20kts, and significant strengthening is unlikely for the next 2 days. After this time, however, shear will relax, and conditions will become much more conducive for development. Because of this, the NHC is forecasting Leslie to be a Category 2 hurricane with 105mph winds in 5 days. One possible variable in the intensification process will be Leslie's extremely slow motion. Slow moving storms tend to cause cold water from deep in the ocean to come to the surface in a process known as upwelling. These cooler waters can act to weaken a tropical cyclone. I do not feel this will be much of a problem, however, and neither does the NHC as they have noted the high ocean heat content in Leslie's area should limit affects of upwelling. I generally agree with the NHC intensity forecast, as it appears strengthening should begin in about 48 hours as they suggest. The track forecast continues to have a degree of uncertainty, but the models have come into decent agreement. The biggest concern for land remains the island of Bermuda, as the official NHC forecast puts the island in the right front quadrant of a strengthening hurricane in 4-5 days. I do not feel impacts will be too severe on the island for a couple of reasons. One is that most buildings in Bermuda are built very well. Another is that it appears Leslie will be rapidly accelerating as it passes by the island. Still, residents there should definitely heed any advice given by emergency management agencies. Large waves and beach erosion will likely be the biggest threats. After it passes Bermuda, Leslie will likely continue a NNW movement before turning N and eventually NE as a trough picks up the storm. Right now direct impacts on the United States East Coast appear very unlikely, but high waves and dangerous rip currents will be major concerns, and residents of the East Coast should avoid the water this week. There are some indications that Leslie will become a very powerful extratropical storm after it loses tropical characteristics. It will be an interesting event to watch for sure.
Figure 1: Official NHC forecast for Leslie.
Figure 2: Tropical Storm Leslie.
Michael Strengthens, No Threat To Land
In the open waters of the Atlantic, tiny Tropical Storm Michael has become better organized today. As of the latest advisory from the National Hurricane Center, Michael has maximum 1 minute sustained winds of 50mph and a minimum central pressure of 1006mb. It is moving NNW at 7mph. Michael has strengthened today as a mid level eye has been evident on microwave images and occasionally on satellite images.
Figure 3: Microwave image of Michael.
Forecast For Michael
The latest NHC intensity forecast brings Michael to 70mph in 4 days. Michael is an extremely tiny cyclone, so there is a large bust potential both ways with the intensity forecast. Small storms like this are usually very vulnerable to any unfavorable conditions, and a sudden increase in shear could easily tear up the system and cause dissipation in the next 5 days. On the other hand, small systems like this can spin up very quickly under the right conditions, and Michael could become a hurricane if this happens. I'm leaning more towards the aggressive solution as I am forecasting Michael to peak at around 80mph. Regardless, Michael is not a threat to land.
Figure 4: Official NHC forecast path for Michael.
Just a quick side note: I (like many of us) am back in school so I won't be on before 3PM most weekdays for the next several months. I may not have time to make many blogs either but I will try to get them out when necessary.
Thank you for reading, have a great night!
Leslie Heads For Bermuda
Tropical Storm Leslie is the main feature being watched in the tropics right now. As of the latest advisory from the National Hurricane Center, Leslie is located about 585 miles south of Bermuda, and is crawling NNW at 3mph. Leslie currently has maximum sustained winds of 60mph and a minimum central pressure of 998mb.
Forecast for Leslie
Leslie is currently disorganized, as strong shear continues to prevent thunderstorms from consolidating over the center. Leslie has maintained a rather impressive area of deep convection for the past 24 hours, but it remains mostly to the south and east of the center. Shear is forecast to remain high for most of the next 24 hours, so strengthening in this period is unlikely. After this, however, conditions are expected to become much more conducive for development, and strengthening is likely to begin by tomorrow night. The official NHC forecast brings Leslie to 100mph in 5 days, which would make it a category 2 hurricane. I think this forecast is reasonable, though it could be slightly conservative, as I think Leslie will be around 105-110mph in 5 days. The track forecast is continuing to become more difficult as model solutions continue to diverge. The most immediate concern for land is the island of Bermuda. It is looking more and more likely that hurricane conditions will be threatening the island in 5-6 days. The official NHC forecast, seen in Figure 1, takes Leslie west of Bermuda, which would put the island on the system's east side, which is normally where the most severe conditions are found in a hurricane.
Figure 1: Official NHC forecast path for Leslie.
Residents of Bermuda should pay close attention to this storm. Beyond this time period, the forecast becomes very difficult. Some models, including the GFS, keep Leslie well clear of the East Coast of the United States, with the only impacts being large waves and rip currents. Other models, including the CMC and as of its latest run the ECMWF, bring Leslie closer to the East Coast, and indicate at least tropical storm conditions possible for New England. Most of the models indicate Leslie deepening significantly, regardless of how close to the coast it gets. I feel a solution more like that of the GFS is most likely, taking Leslie well offshore, but the overall trend has been to bring her closer, so everyone on the East Coast should keep an eye on Leslie.
Figure 2: Tropical Storm Leslie. The center is located on the very NW edge of the deep convection, indicating shear.
99L May Develop, But Won't Threaten Land
In the central Atlantic, an area of disturbed weather, Invest 99L, has been organizing today. As of their 2PM Tropical Weather Outlook, the National Hurricane Center is giving 99L a 60% chance of development in the next 48 hours. Conditions are fairly favorable for development in the short term, and I put development odds at about 70%. 99L is an extremely small system, and will be no threat to land regardless of development.
Figure 3: Invest 99L.
Disorganized John No Threat
In the East Pacific, Tropical Storm John is currently located about 290 miles WSW of the southern tip of Baja California as of the latest advisory from the National Hurricane Center. He is moving NW at 14mph. John's maximum sustained winds are estimated to be 40mph, and his minimum central pressure is 1002mb. John is being battered by high shear, as evident by his exposed low level circulation. He is also moving into cool waters, so weakening is likely, and I expect him to become a remnant low late tomorrow or tomorrow night. John is no threat to land.
Figure 4: Tropical Storm John, with a fully exposed center.
Thank you for reading! Have a great week!
Halfway Through The 2012 Season
It's hard to believe, but we are halfway through the 2012 Atlantic Hurricane Season. I'll have more about that later on in this post. First though, there are some very active tropics to get to, as would be expected near the climatological peak of hurricane season. There are currently three areas of interest in the Atlantic. The biggest threat right now is Tropical Storm Lesile. As of the 11AM EDT advisory from the National Hurricane Center, Leslie is located nearly 300 miles north of the Leeward Islands, and is moving NW at 15mph. Leslie currently has maximum sustained winds of 65mph, and a minimum central pressure of 997mb.
Forecast for Leslie
Leslie is an extremely sheared tropical cyclone, as evident by nearly all of the heavy thunderstorm activity being located to the south of the center, as seen in Figure 1.
Figure 1: Tropical Storm Leslie. Shear is evident as the center can be seen to the north and west of the strongest convection.
Leslie is also fighting a dry environment. Due to these unfavorable conditions, strengthening is unlikely for the next 3-4 days, as the official forecast shows Leslie weakening slightly in that time. It wouldn't surprise me if it weakened more than indicated as conditions just won't be favorable at all for tropical cyclones. Beyond 4 days, however, it appears shear will relax and give Leslie an opportunity to strengthen, and the official forecast from the NHC indicates Leslie will be a minimal hurricane in 5 days. The track forecast for the next 5 days keeps Leslie moving NW for the next day or so, followed by a NNW and then N turn, possibly followed by a bend back towards the NW in 4-5 days. It should be noted that Leslie is not expected to move much during this time period, as it will likely slow down tomorrow. What happens beyond 5 days, both with track and intensity, is uncertain. The most immediate issue will be the island of Bermuda, as it looks like it will be in the future path of Leslie. By the time it gets to this point, Leslie may have intensified quite a bit, as several models are indicating, so anyone in Bermuda should be monitoring the situation. It is too early to determine any possible impacts on the United States, but most indications are that Leslie will stay offshore and only provide some large ocean swells.
Figure 2: Official NHC track forecast for Leslie.
As would be expected of a system in Kirk's location, he is weakening and accelerating. His circulation has become elongated, and he will likely dissipate soon. Kirk currently has maximum sustained winds of 50mph and a minimum central pressure of 1002mb as he races NE. Kirk is not a threat to land.
Figure 3: Tropical Storm Kirk, rapidly being swept away towards the NE.
Invest 99L Little Threat
In the open waters of the central Atlantic, an area of disturbed weather, Invest 99L, is being watched for development by the NHC. In their latest Tropical Weather Outlook, they gave the disturbance just a 10% chance of development in the next 48 hours as environmental conditions are not conducive for development. I would put these odds slightly higher at about 25% since these small systems have a tendency to spin up unexpectedly. Regardless, 99L is no threat to land.
Figure 4: Invest 99L, showing a tight circulation but little convection.
East Pacific Remains Active
Former Hurricane Ileana dissipated today over cool waters, with nothing left of her except a convectionless swirl. This remnant circulation should dissipate in the next few days and it will not threaten any land areas.
Figure 5: Remnant low of Ileana.
The next potential system in the East Pacific is located about 350 miles SSE of Baja California. This disturbance, Invest 99E, is moving WNW at about 15mph. It is being given a 90% chance of development in the next 48 hours, and I agree with this percentage. 99E's WNW motion means it is heading away from the coast of Mexico, so it should not be a threat to land.
Figure 6: Invest 99E. It is a very large disturbance so it may need to consolidate a bit more before being classified.
Halfway Through the Season
Three months down, three to go. We are now halfway through this year's Atlantic Hurricane Season. This season has been similar to last season in some ways- a very large number of named storm, but several of them being weak and no threat to land, but with one big hit on the United States. Last year it was Hurricane Irene, and this year it was Hurricane Isaac. Both were category 1's at landfall, but both were very large storms that provided impacts greater than a normal storm of their category. 2012 has featured two storms that formed before the official start of the season (Alberto and Beryl) and has been one of the most active years on record in terms of named storms. We've seen one of the greatest forecasting challenges of all time (Debby) as well as a near major hurricane near the Azores (Gordon). The theme of the year so far has been dry air, as several storms, including Isaac, struggled with this issue.
What to Expect for the Rest of the Season
We are nearly to the climatological peak of hurricane season; it will occur in about a week. Early this season, predictions were for an abrupt shutdown to the season by early to mid October as a predicted El Nino set in. The El Nino has been very slow to develop, however, and may never develop at all, though effects from the warmer than normal Pacific waters have been evident in our basin. This delayed El Nino likely means that while activity should slow down significantly by October, the season should not completely shut down and we could see 2-4 storms between October and November. Throw in about 4 storms in September and we could be looking at a grand total of nearly 20 storms, much higher than originally predicted, though some have been rather pathetic and short lived. As always, it is impossible to pinpoint any potential land impacts, so the best thing to do is keep an eye on whatever forms.
Thank you for reading, and have a happy Labor Day!