Monthly Archives: September 2010

Hurricane Igor, TS Lisa, Invest 95L, PGI47L

Hurricane Igor after battering Bermuda with category one hurricane winds has left and now is expected to pass by southeastern NewFoundland. Igor is expected to to become extratropical within 24 hours.

What was Tropical Depression Fourteen has been upgraded to Tropical Storm Lisa as of the 5:00am Advisory this morning by the NHC. Tropical Storm Lisa is headed directly north, but the motion now is in a weak steering current and in 24 hours Lisa will be begin to turn more NW due to a subtropical ridge from the north which will be building in. There is some disagreement within the models as to whether or not Lisa will be turned to the west because of the ridge amplifying or will there be a break in the ridge later on on the forecast period. The vertical shear will be very low for the next 48-72 hours so Lisa will have a chance to strengthen some but the mid level moisture envelope will be drying out and along with some cooler SST’s – strengthening will be limited.

PGI46L has now been designated as Invest 95L. For the next 24-36 hours, there is the possibility of some dry air wrapping into the system along with some northerly shear. This will limit some development. Beyond the forecast period, the environment will be conducive for development and most models want to keep 95L on a WNW path and eventually having landfall near Nicaragua but a possibility of of a more NW – to NNW and into Cuba/South Florida exists. Therefore, this system does need to be monitored carefully.

PGI47L which is just off the African coast will probably not be threat in any way and most models believe this sytem will dissipate.


Hurricanes Igor, Julia & PGI45L, PGI46L, & New PGI47L

Hurricane Igor, now a category 2 storm is still a large and dangerous hurricane and the center is poised to either make landfall on the island of Bermuda or possibly just to the side of it. Conditions will start to deteriorate sometime tonight and there is the possibility that Igor may intensify and become a category 3 storm before landfall. Igor should start the transitional period of becoming extratropical in about 3 days

Tropical Storm Julia which has been assaulted for a day or two and now the strong northerly shear has displaced the deep convection and the low-level center is now exposed. Strong shear from the outflow from Hurricane Igor will to continue to weaken TS Julia and Julia should be a remnant low within 48-72 hours. Eventually, Julia will be absorbed by Hurricane Igor.

What was PGI45L has now been designated as Invest 94L. Environmental conditions are somewhat conducive for gradual development of Invest 94L. At least one model is forecasting that 94L will become a minimal tropical storm in about 5 days.

PGI46L has not developed in any way and there is the possibility it may dissipate. This is something that would still need to be monitored.

A new pre-invest system PGI47L that is still inland in Africa has some decent circulation but there is the chance that there might be dry air which might hinder development even though shear is forecast to be light. The very early forecast for PGI47L once it is in the Atlantic is to head WNW to NW and later NNW.


Hurricanes Igor, Julia, Karl & PreInvest PGI45L

Hurricane Igor still a threat to Bermuda with winds of 120MPH and is still a Category 3 storm. The inner eyewall of Igor has been broken on the west side, but there is still time for this to regenerate. Igor is an environment of very light shear and warm SST’s. Within 48 hours, Igor will start to feel the effects of cooler waters and some gradual increasing of south to southwesterly shear. The steering flow of a subtropical ridge will keep Igor on a NW – NNW for the next few days. After that forecast period, a series of strong short wave troughs that is located in the Northeastern US will turn Igor NE.

Hurricane Julia is slowly decreasing in strength mostly due to an increasing N to NW shear from the large upper-level outflow from Hurricane Igor. The outflow is from top of the storm Igor and rotates clockwise. Continued weakening is forecast in two of the models and the Dynamical models are forecasting dissipation with Julia being absorbed within the circulation of Hurricane Igor.

Dangerous Hurricane Karl is a Category 3 storm. The eye of Karl will be making landfall in Mexico within minutes, if not now. Karl will start to lose strength once the eye has made landfall due to the interaction with land and the high mountains in Mexico. Major flooding will be a problem.

ADDENDUM: The Eye of Hurricane Karl has made landfall just northwest of Veracruz, Mexico – just before 2PM EST.

Pre invest PGI45L is still a very series of thunderstorms associated with a broad low pressure system. Since this is the peak of the hurricane season and this area is in the Cape Verde Islands – this system has to be monitored. I feel any development, if any, will probably head NW and away from any land masses.


Hurricane Julia, Hurricane Igor, Invest 92L (now TS Karl), PGI45L

Tropical Storm Julia had been upgraded to Hurricane Julia as of the 5:00am advisory. Julia is in an area with decent SST’s which will allow for some possible further intensification for at least another day or two. After that period, and even though Julia will still be in warm waters, Julia will be feeling the North to Northeasterly shear basically the outflow from Hurricane Igor. Julia is forecast to make a NW heading due to a mid to upper level trough for 24-48 hours, then a sub tropical ridge will cause Julia to return back on a WNW heading for a few days. Beyond that forecast, the models are in agreement on Julia turning NW then NNW as Julia will be along the Western periphery of at previously discussed ridge.

Dangerous Hurricane Igor has finally started to turn toward WNW then will make a turn toward the NW. A weakness in the sub tropical ridge will make Igor turn to the NW and later a NNW. Exactly when these turns will happen in unclear. The U.S. coast should have no problems except possible swells, but Bermuda might be right in Igor’s way. If Igor delays these turns then Bermuda may get the N and NE(strongest) side of the storm. If Igor starts the turns much earlier then Bermuda make get the weaker side of the storm or just possible Tropical Storm force winds. As Igor continues to gain latitude, Igor will begin to be in cooler waters and lose some of his strength – possibly a Category two or high Category one.

Invest 92L today seems the it is finally trying to get something together. Good convection has been present for several hours with the exception in the east and southeast quadrants. It does seem to have some very good, but not excellent cyclonic spin. If 92L can continue to do as well during the rest of the day, 92L may become a tropical depression. Tropical storm is not out of the question but I doubt it as 92L is running out of time before it comes ashore in the Yucatan.

As of the 5:00pm Advisory Invest 92L has been upgraded to Tropical Storm Karl. TS Karl has maximum winds of 40 MPH but is the forecast is expected for Karl to strengthen slightly. Due to land interaction, any increase in strength should be gradual.

PGI45L is a system still over the African continent but will be coming off the coast soon. This a large system and will be monitored for further development.


Dangerous Hurricane Igor, & Tropical Storm Julia

Dangerous Hurricane Igor is now a Category 4 and there is a possibility it may attain Category 5 status. Igor will be going though a ERC, and during that time Igor will weaken slightly but will still be a major hurricane. Unfortunately, no one can tell when the ERC will start. Igor is still on a Westward track but within 24-48 hours, Igor should begin a WNW track due to a long wave trough in the Western Atlantic. There is some disagreement about the trough flattening out in about 3 days, which would bring Igor back on a westward track. This will have to be seen and the forecast discounts the possibility for the moment.

TD Twelve which is in the far Eastern Atlantic has been upgraded and is now Tropical Storm Julia as of the 11PM advisory. TS Julia is still having some moderate Easterly shear but this will be decreasing within 12-18 hours and is forecast to remain light for the next few days. TS Julia will be in very warm SST’s and this will allow steady strengthening so Julia is forecast to attain hurricane status. Thereafter, Julia will start to move into cooler SST’s and also will start in an area of increasing southwesterly shear. Julia will be on a WNW track and then later the storm is forecast to turn NW due to a weakness in a mid-level ridge.

A very large tropical disturbance still inside Africa will be rolling of the coast soon. This is another of the train of waves coming off Africa.


Invest 92L, TS Igor

A wave in the eastern Caribbean, just south-southeast of the Windward Islands has become better organized and has been designated as Invest 92L. Once Invest 92L can move away from the South American coast, 92L will be in a position to strengthen and develop into a tropical cyclone. Most models are in agreement of 92L developing into a hurricane and the flow will be a W to WNW movement. An outlier model (the Canadian CMC) model has it closer to Cuba and possibly Florida. Shear will be very light and the environment will be conducive for further development. The pattern for this system will be for 92L to have landfall toward the Yucatan and if it follows a more WNW-NW flow it will get into the southern GOM and this might be another threat to Texas if it holds together.

Tropical Storm Igor overnight and this morning was being assaulted by moderate easterly shear but as the day progressed the shear began to relax a little and this allowed deep convection within the center to form along with an expanding convective field. There was a weak low to the northeast of Igor but that has been absorbed by Igor. The shear will be relaxing over the next few days along with warm SST’s and a very moist envelope, Igor will be in an environment conducive for steady intensification. Both Statistical and Dynamical models are in agreement for Igor to be a hurricane with 2-3 days. Further intensification is also forecast. There is a mid-level ridge to the north of Igor and this will keep Igor on a W to WNW track along with a gradual increase of forward speed. On day 4 Igor will be be in the Central Atlantic and will be near a trough which should cause Igor to turn toward the NW. Exactly how much of a turn and when has caused the different models to slightly disagree. Some models tend to believe that Igor will follow a path similar to Danielle and therefore the will not affect Bermuda where as other models are taking a slower track and taking a path similar to Earl being between the coast of the SE U.S. and Bermuda.


Tropical Storm Igor

Invest 91L has been upgraded to Tropical Storm status as of the 11AM Advisory. TS Igor came off Africa and was very healthy right from the beginning. Even before the upgrade, Igor had very good convection and the cyclonic turning was getting better each hour. At the present there is some easterly shear over Igor but shear will lift up and in a day or two the shear will be will then be light for a few days. This will allow intensification for days 2-4 and models are in agreement on this scenario. On day 5 shear is forecast to strengthen some and slow down further intensification.

A mid-level ridge in the eastern Atlantic is forecast to strengthen and this will keep TS Igor on a westerly track. This will also increase the forward speed of Igor. After a fews, a trough that is over the central Atlantic may cause the ridge to weaken and this may allow a more NW track. Beyond 5 days, any forecast would be prone to major error.


Invest 91L and ex-Gaston

Ex-Gaston who seems to have been around forever has lost most of it’s cyclonic spin is now just under Puerto Rico and the last satellite imagery of Gaston was showing the best convection it has had in a long time. The only problem with Gaston is that he will soon be headed right into Hispaniola. The mountain range there can be very high and has many a time either disrupted a storm or killed it. If Gaston only clips the mountains, Gaston may survive and possibly may develop while in the the western Caribbean.

A tropical wave that has just come off Africa has been designated as Invest 91L. This tropical wave does have some decent cyclonic turning but there is some wind shear of about 20-30 knots just north and northwest of it. The shear will relax within the next 24-48 hours. Some on the models have just been initialized thus there may be errors or bias within them. Several models are suggesting this will be our next tropical cyclone.


Tropical Storm Hermine

What was Invest 90L then updated to TD Ten has now been upgraded to Tropical Storm Hermine. Overnight, TS Hermine started to head N which did give it a little more breathing space to develop. It is still forecast to make the turn toward the NW but when that turn will happen is still unclear. The track for Hermine has shifted right from the previous one and this places TS Hermine right again the Mexico/Texas border. TS Hermine has a very ragged CDO(Central Dense Overcast), but unless it start to make the turn to the NW, the CDO should begin to have a better overall appearance. Additional strengthening is forecast but I don’t think it will have enough time to become a minimal hurricane even though the SST’s are in the 30°C-31C° range. I do believe the forecast track will need to be adjusted slightly to the right again as the ridging over the northern Gulf has been slow in coming.


Tropical Depression Ten

Invest 90L has now been upgraded to a depression this evening with the 11PM advisory. TD Ten is favorable for some intensification till land interaction will restrict further development. At the moment TD Ten in headed NW to NNW. There is some disagreement between the models as to when the left turn will occur. A ridging will be developing over the northern Gulf of Mexico. All models are in agreement on this scenario.