2013 Steering Pattern / Early indicators

[Hurricaneman]

The instability in the tropical atlantic has finally gone above normal, could someone put up a graphic of that

[cycloneye]

The instability in the tropical atlantic has finally gone above normal, could someone put up a graphic of that

[cycloneye]

This is the CFSv2 May forecast and it shows light trade winds in Tropical Atlantic.



http://www.cpc.ncep.noaa.gov/products/p ... T/monthly/

[WeatherEmperor]

Lately there have been a lot of cold fronts coming through the east coast. The last one just came through yesterday. Does anybody have any maps or charts for long range forecasts to see if this will continue or will we see a pattern change with more high pressure ridge off the east coast?

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[cycloneye]

The vertical instability has gone again below normal after briefly going slightly above.

[cycloneye]

Here is the CFSv2 shear forecast and it looks like normal to slightly below normal shear will occur during the August/September/October period.

[SFLcane]

Causes of the unusually destructive 2004 Atlantic basin hurricane season

http://ruby.fgcu.edu/courses/twimberley/EnviroPol/EnviroPhilo/Causes.pdf

[cycloneye]

IMO the ITCZ is too low in latitude (Equator on April 30) considering that we are going into May. Eventually it will begin to lift northward.

[Hurricaneman]

IMO the ITCZ is too low in latitude (Equator on April 30) considering that we are going into May. Eventually it will begin to lift northward.

Look over Africa where the monsoon trough is at 18N, usually during the peak of the hurricane season the ITCZ is usually within 5* of it after its move north so I do expect the ITCZ between 12N and 18N in a few months, may be between 5N and 10N by the end of May

[Hurricaneman]

The trough\ridge pattern if it doesn't change could put most of if not all of the gulf at high risk considering the mean trough is over the great lakes and midwest which I hope does change towards a more east coast trough and deflect these storms out to sea which is a wait and see situation

[WeatherEmperor]

What does this current pattern mean for the east coast? Also, how about all the rain in south florida? It looks like the rainy season started early this year. Does that also have implications for the pattern setup?

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[SFLcane]

What does this current pattern mean for the east coast? Also, how about all the rain in south florida? It looks like the rainy season started early this year. Does that also have implications for the pattern setup?

Sent from my HTC EVO 4G LTE

There's no strong scientific correlation between rainfall/dry may's and a hurricane strike in South Florida. We're talking about two different scales, large scale weather systems and a sub-large scale system like a tropical cyclone embedded within the large scale. There are too many factors involved in the development area, timing and track of a tropical system that can't be correlated 2-3 months in advance. Everything could set up for a potential Florida impact on the large scale, but if a storm moves too far south, it stays in the Caribbean, or if the ridge weakens temporarily, it misses us by 200 miles to the north. That's why the correlations are very weak, at best, which implies a lack of scientific support for something as specific as a South Florida landfall.

[chaser1]

What does this current pattern mean for the east coast? Also, how about all the rain in south florida? It looks like the rainy season started early this year. Does that also have implications for the pattern setup?

Sent from my HTC EVO 4G LTE

There's no strong scientific correlation between rainfall/dry may's and a hurricane strike in South Florida. We're talking about two different scales, large scale weather systems and a sub-large scale system like a tropical cyclone embedded within the large scale. There are too many factors involved in the development area, timing and track of a tropical system that can't be correlated 2-3 months in advance. Everything could set up for a potential Florida impact on the large scale, but if a storm moves too far south, it stays in the Caribbean, or if the ridge weakens temporarily, it misses us by 200 miles to the north. That's why the correlations are very weak, at best, which implies a lack of scientific support for something as specific as a South Florida landfall.

I'll second what SFLcane stated above. As to the first part of your question however, I will tell you that the present steering pattern would tend to imply greater ridging in the far Western Atlantic and depending on the strength and orientation of such a blocking mechanism, would certainly indicate a heightened risk to parts of the Atlantic Seaboard and/or the Gulf coastal areas. It remains to be seen whether the pattern at present will represent the long term average during the summer and fall months, but it would seem to fit those predicting greater an increase number of S.E. Conus landfalls. For what it's worth, my present mindset is that this type of over all set up with the main long wave trough over the midwest indicates a greater threat to the Bahamas, W. Cuba, Florida, Central America, Yucatan, and N. Gulf Coast. Remember, a strong 500mb ridge over or just east of Florida however, could just as easily imply tropical cyclones would be shielded from most of those areas mentioned above (though long range projected lower surface pressures for the W. Atlantic would be less likely to coincide with such strong 500mb ridging over the same area IMO)

[TropicalAnalystwx13]

This is my hurricane strike probability map for 2013.



Since they're not colored...

The Bahamas - High chance
Lesser Antilles - High (North), Medium (South)
Bermuda, Azores, Cape Verde Islands, Newfoundland - Medium

Be prepared for every season regardless of the forecast.

[cycloneye]

The Caribbean vertical instability looks to be a little higher than average.

[Hurricaneman]

Going off of the instability map, it looks like as if you may not get many storms east of 50W, but west of 50W could be in serious trouble if the instability continues as is, similar to 2005 in terms of where the biggest instability is maybe just a bit farther west with the biggest instability than 2005 FWIW.

In 2005 the instability east of 50W was low but the area between 45 and 60W was immense which if you look at the tropical atlantic chart put it above normal so I would think something close to a mix of 2005 and 2004 based on the 500mb pattern and instability

[cycloneye]

If the CFS forecast holds for the next few months then U.S landfalls will have a higher possibility to occur.

[Hurricaneman]

I was looking, but the QBO could take the hurricane numbers down a little as in it could cause a little upper shear in the MDR

[ROCK]

This is my hurricane strike probability map for 2013.



Since they're not colored...

The Bahamas - High chance
Lesser Antilles - High (North), Medium (South)
Bermuda, Azores, Cape Verde Islands, Newfoundland - Medium

Be prepared for every season regardless of the forecast.

you might as well color all that in red and call it a day....

you gave the entire Texas coast 0-20% chance. You do know that Texas has a big coast line? If we are using 2004-2005 as comparable years then I would change this map. Just sayin if you look back at those years.

[TropicalAnalystwx13]

This is my hurricane strike probability map for 2013.



Since they're not colored...

The Bahamas - High chance
Lesser Antilles - High (North), Medium (South)
Bermuda, Azores, Cape Verde Islands, Newfoundland - Medium

Be prepared for every season regardless of the forecast.

you might as well color all that in red and call it a day....

you gave the entire Texas coast 0-20% chance. You do know that Texas has a big coast line? If we are using 2004-2005 as comparable years then I would change this map. Just sayin if you look back at those years.

My forecast was not based solely on analogue years. It takes into consideration long range model guidance for 500mb geopotential heights and forecasts from many different branches of NOAA regarding the development of the pattern for this summer.