2PM advisory/model run update

Isaac is currently located at 23.9N 81.5W  top winds are  60 mph, down slightly and this is likely a sign that Isaac is using its energy to organize its inner core rather than intensifying. The central pressure is 994mb which is down, a sign of intensification. Sometimes before RI (Rapid intensification) the pressure suddenly drops and the winds are steady or weaker only to, 12 hrs later, skyrocket 20, 30 or even 40 mph higher 24 hrs later. This could be what is happening now or it could be dry air that has gotten ingested into the system.

Isaac is moving quite swiftly to the NW at 18mph and will make landfall near New Orleans as a CAT 3. The important thing is though, Isaac is a very large storm with a TS wind field of over 210 miles shown here:

This image shows all areas with TS force winds as of 11 AM this morning. Note how large the orange area is. The area of TS force winds will continue to grow as Isaac intensifies. This map also shows areas under watches and warnings.

Lately Isaac has been firing convection near the center and organizing an eyewall. Long range radar out of Key west shows this quite clearly.

The COC/Eye/LLC (COC=Center of circulation. LLC=Low Level Center) is where the swirl is. You can see that it is nearing Key West and also filling in, a sign of weakening but any weakening will be temporary.

This is the latest Advisory from the NHC :


2:00 PM EDT Sun Aug 26
Location: 23.9°N 81.5°W
Moving: WNW at 18 mph
Min pressure: 994 mb
Max sustained: 60 mph

Isaac will strengthen throughout the day with Hurricane force winds expected by tonight. Isaac will then continue to move off the the NW or WNW and may wobble W or N at times. Intensification is expected peaking at a 130 or 135 mph storm if a track across the central GOM pans out. If Isaac moves more NNW or N a weaker storm can be expected. The reason is that OHC (Ocean Heat Content-the fuel for tropical cyclones) is lower in the East GOM than elsewhere because of eddies in the Loop current which is a hot current that runs from the WCAR (West Caribbean)  up through the Yucatan Channel and into the GOM before exiting through the FL straits and turning into the Gulf Stream. Every few weeks it sheds a large warm eddy into the Central GOM. these eddies were plentiful during the active 2005 season and caused Katrina and Rita to explosively deepen. A hot eddy like these is in the Central GOM now and a cooler eddy in in the Eastern GOM so if Isaac takes a westerly track , and goes over the hot eddy than a stronger storm (145mph) can be expected. If an easterly track plays out than a weaker storm (110mph) can be expected. New Orleans is also in danger from a 7-9 foot surge and 10+ foot breakers. Model guidance also wants to take the storm into New Orleans

Any track to the West of New Orleans would be much worse putting the city in the right front quad; the most dangerous. Regardless, all interests in the N GOM should be preparing for a major storm.

Stay tuned!

-Jack

Isaac shaping up to be a deadly and dangerous storm.

TS Isaac is organizing over the FL Keys today and is currently moving WNW or NW with wobbles all over the place. Radar shows a large eye with a CDO (Central Dense Overcast) feature moving over Miami and points south. New models will be running at 12 and at 2 so a full update can be expected then but for now, Models are clustered tightly around New Orleans and have been consistant for around a day now. THERE IS HUGE UNCERTAINTY THOUGH and Isaac could make landfall anywhere from Panama city FL to Port Arthur TX. Isaac will likely hit as a CAT 3 storm with 120 mph winds. a weaker system can be expected if the track is East towards FL and much stronger if a TX track pans out.

Stay tuned, full update by 3:30PM EDT!

Isaac could ruin the RNC

TS ISAAC will have the potential to really be a heck of a storm… It is very large and therefore has the potential to be a real mess for a large area. 1st stop: Haiti. As Isaac moves WNW or NW it will likely consolidate into a hurricane. Regardless of wind speeds, Isaac is very moist and capable of dropping heavy rains. Haiti is very susceptible to heavy rains due to deforestation so any rain can cause dangerous mudslides. Adding to the problem over 200,000 people live in makeshift tents/shelters on muddy ground so rain could easily leave many people homeless. Isaac likely will not stop there though. After traversing Hispaniola, likely leading to a humanitarian crisis, he will churn into the Straits of Florida. The water temperatures will be in the 90 degree range. When any tropical entity (TD, TS, or Hurricane) moves over water like this, if shear is low enough, and moisture in plentiful supply then it is a lot like dumping 100 gallons of gasoline on a fire. Sadly for the US, all factors will be in play for RI (rapid intensification) to occur 24 hrs or so after emerging from land. Isaac will then continue WNW or NW into the bathwater of the GOM. RI could continue or resume again here. This is where things get tricky. There is another TS spinning in the C Atl named Joyce. Joyce will move NW for the next 4 to 5 days before causing us meteorologists to argue about what will happen while scratching our heads having no clue what the heck is going on. Here is why; Everything is fine and neat for 4 days. then when day 4 arrives here is the situation: Joyce will be located a few hundred miles south of Bermuda. Isaac will be near Key West. Isaac and Joyce will both get larger and more powerful as time goes on. Monday (day 4) they could interact (meaning 1 storm has an effect on the other).

STAY TUNED!

-JAck

Suspicious Models…

In my roundup of morning model checks, I saw a something that interested me. It  was that 2 models predict that a storm, TD9, will impact us. They think that This storm will hit GA then traverse NC and VA then move back out over water and re strengthen before hitting Long Island and moving into the Gulf of ME. This would prove to be a cataclysmic scenario for most of the East coast. Fortunately this is not anticipated but something to watch…

STAY TUNED!!

-JAck

Full tropical update

The full version of the tropical update is as follows:

There are several areas of interest now, Gordon, 94L, 95L, a wave off Africa and a wave approaching the Antilles.

Gordon
Initial Winds: 70MPH
Pressure: 987MB
Classification: TS

Gordon will track NE and become extratropicial while moving towards the coast of Spain where showers are likely at most.

94L:
Initial Probability: 80%*

94L will likely continue to move WNW or W. Following in the shadow of another tropical wave 94L is expected to move north of Hispaniola and Cuba. From there, it could make landfall anywhere from Havana Cuba to Halifax Canada. Depending on where it will make landfall, it could hit at a strength of a weak TS or a strong hurricane. THIS STORM IS A THREAT TO THE US!! Stay tuned for future updates!! 94L has a large well defined circulation but lacks heavy thunderstorms to be a classified TD.

95L:
Initial probability: 30%*

95L will likely drift around the NW GOM (Gulf of Mexico) While slowly growing in organization. It could eventually impact the Gulf coast next week.

African Wave:
Initial probability: 20%

This African wave will be moving W while developing at a steady pace. There is high uncertainty with this forecast and THIS STORM COULD ALSO IMPACT THE US IN THE FUTURE!!!

Wave Approaching the Antilles:
Current probability: 0%

The reason I mentioned this Wave is that it is helping 94L develop by leaving a moist environment in its wake. This wave has a small chance of development once it reaches the Western Caribbean.

STAY TUNED!!!

-JAck

Tropical Trouble

Just a quick update… more tomorrow. The tropics are on fire tonight as Hurricane Gordon moves into the Azores as it transitions to an extratropical low. Also 94L and 95L are of concern.

GORDON: CAT 1 85mph winds. Will move through the azores weakening as dry air, high shear and cold waters take their toll on him. Should be extratropicial be tomorrow night.

94L: Is a low pressure system roughly 1/2 way between Africa and America. It is likely to develop while moving W at 20 mph. THIS COULD BE A THREAT TO THE US IN A WEEK AND A HALF OR SO. LARGE UNCERTAINTY.

95L: Is a low pressure system in the W GOM. Some weak development is possible as it drifts around the Western GOM.

STAY TUNED!!!

-Jack

Reliably hype-free weather info for Western Maine and New Hampshire from amateur forecaster Jack Sillin

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