Low Shear in Atlantic

[Anthonyl]

I have been viewing the shear tendancy maps for the past couple of days and notice shear to be qiut low for this time of the year. I noticed something comparingly similar to this in late April last year, but saw a drastic ramp up of abnormally higher shear values as El Nino became more pronounced. I need to know whether this is normal seasonal values or are we seeing the tell tale signs of an establishing La Nina pattern for the upcomig season. I also observed that waters in the equatorial regions of the Pacific have also continued to cool.

[Coredesat]

Shear doesn't look low to me:

[web]http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8wxc.GIF[/web]

The shear in the far southern Caribbean is beginning to relax, but that subtropical jet has not budged as of yet.

[hial2]

The shear in the far southern Caribbean is beginning to relax,.

Isn't that the general area of danger @ the beginning of the season??

[Coredesat]

It is, but there's also dry air - the basin as a whole is still in a winter/early spring-like pattern.

[Opal storm]

Yeah we're still a long way out before anything happens out there.

[canegrl04]

Lets see what it's like by June.If shear is low,its an ominous start to hurricane season 2007

[MiamiensisWx]

Pressures in the MDR appear lower than last year. In addition, note the favorable divergence within the ITCZ and primary flow in the deep tropical Atlantic. Unlike the mean flow in 2006 (which was westerly), we are seeing easterlies in the eastern Atlantic. It is clearly very early, but could this signify a more favorable environment for Cape Verde development? The Bermuda-Azores High is further north and extends further to the west. If this setup continues into September, we may see more landfalls and a more conducive environment (both features were not present in 2006). I'm not jumping to conclusions but I'm taking notice of observations.

In fact most of the western Atlantic is behaving in a more favorable manner than 2006. Pressures are lower in most of the Caribbean Sea. Shear is high but this is typical before late August and September. Overall conditions look much different than 2006. This is going to be an interesting season. Let's hope for no landfalls and a great fish tracking season! As a south Florida resident, I dearly hope we get another break.

[NDG]

Actually, vertical shear in the Caribbean over the past few days and overall it has been under climatology, along with other trending favorable conditions it would be safe to say that we could have an active beginning of the hurricane season in the Caribbean, and since we know that ENSO is going to stay at least neutral, conditions in the Caribbean should stay favorable through September and or October.

[tgenius]

So We are about 37 days from the start of the season... I'm hoping the shear stays up (or heads up if it isnt) to prevent the development of some monster storms.

[wjs3]

NDG:

Do you have any more information about those shear plots you posted? I've never seen that in chart form and vs climo before.

Where did you get it? How's it calculated (what levels/stations? Or maybe it's satellite/cloud wind derived???). Is it available in chart form vs climo like that for other parts of the Atlantic/Carib/Gulf?

Thanks

WJS3

[NDG]

I believe is satellite based estimate, I think it comes from the Colorado University team. And yes they do have charts for the other parts of the Atlantic and eastern Pacific area, I have the link at my PC at home, will post the link for the other areas later today.

[wjs3]

Thanks. I'll poke around at the CSU site in the meantime.


WJS3

[wxman57]

I have been viewing the shear tendancy maps for the past couple of days and notice shear to be qiut low for this time of the year. I noticed something comparingly similar to this in late April last year, but saw a drastic ramp up of abnormally higher shear values as El Nino became more pronounced. I need to know whether this is normal seasonal values or are we seeing the tell tale signs of an establishing La Nina pattern for the upcomig season. I also observed that waters in the equatorial regions of the Pacific have also continued to cool.

Careful not to confuse shear tendency maps with wind shear. The shear tendency maps only indicate where shear is increasing or decreasing, they do not indicate the amount of shear across the tropics.

[Coredesat]

Careful not to confuse shear tendency maps with wind shear. The shear tendency maps only indicate where shear is increasing or decreasing, they do not indicate the amount of shear across the tropics.

Indeed, looking at the map I linked earlier, shear has increased again over most of the basin, although the jet seems to have moved a bit.

[NDG]

Thanks. I'll poke around at the CSU site in the meantime.


WJS3

Here you go:

Atlantic average vertical shear index

E Caribbean average vertical shear index

W Caribbean average vertical shear index

GOM average vertical shear index

E coast vertical shear index

Subtropical Atlantic vert shear index

West. E Pacific vert shear index

E Pacific vert shear index

[drezee]

Shear is Back!!

[milankovitch]

http://www.weatherunderground.com/blog/ ... amp=200704

http://www.cpc.ncep.noaa.gov/products/a ... cast.shtml

Forecast shear from CPC NCEP coupled forecast system model