cdcollura
EF5
Good day,
The Atlantic hurricane season, in my opinion, is pretty much over.
Ofcourse, since I said this, there would be a category-5 hurricane next week in the Gulf!
Anyway, what is going on is there is a substantial amount of upper-level wind shear that has supressed hurricane development this year. Also, if a storm did get going, it recurved (went from a westerly motion towards the US, then turned north, then NE staying out at sea). The presence of upper-level lows and troughs caused this, which is indicators of an El Nino.
El Nino causes the subtropical branch of the jet stream, including air over the northern tropics, to be stronger and / or posess a stronger westerly wind component (causing shear and / or storm recurverature).
Also, an El Nino causes drier conditions in Africa, so the SAL (Saharan Air Layer) became a drying issue to developing tropical systems this year. The trade wind inversion, caused by subsidence aloft, also was an issue this year.
The remaining threat, which is what needs to be watched during October, or even into November, is development over the SE Gulf or NW Caribbean. If a storm forms there, it most likely will recurve and move NE towards the US / Florida. The Gulf of Mexico has not been "tapped" yet for heat content either. I still feel that if a storm forms in that region, there will be shear to disrupt it, so a storm like Wilma last year is unlikely, but not impossible.
Such storms would not devleop from tropical waves, but remnant vorticity associated with stalled frontal zones in the NW Caribbean / SE Gulf.
Now you are wondering about the NAO (North Atlantic Oscillation), the cyclic shift of the NA current in negativce cycle, beginning in 1995 which caused an upswing in hurricanes. Yes, it is still there, but other things are counteracting it (like El Nino). Remember in 1997 there was not many storms, because of El Nino, and 1995 there were 21 storms, both with a -NAO.
El Nino this year started to develop by July. Looking at the OTIS (US Navy Oceanography Fleet page FNMOC), the SST Anomaly already shows 2-3 degrees higher than normal off South America in the Pacific near the Equator, extending out into the ocean westward. A La Nina appears below normal, and is the opposite. El Nino becomes strongest around late December (Christmas), hence the spanish name for "Boy Child" or "Christ".
The Atlantic hurricane season, in my opinion, is pretty much over.
Ofcourse, since I said this, there would be a category-5 hurricane next week in the Gulf!
Anyway, what is going on is there is a substantial amount of upper-level wind shear that has supressed hurricane development this year. Also, if a storm did get going, it recurved (went from a westerly motion towards the US, then turned north, then NE staying out at sea). The presence of upper-level lows and troughs caused this, which is indicators of an El Nino.
El Nino causes the subtropical branch of the jet stream, including air over the northern tropics, to be stronger and / or posess a stronger westerly wind component (causing shear and / or storm recurverature).
Also, an El Nino causes drier conditions in Africa, so the SAL (Saharan Air Layer) became a drying issue to developing tropical systems this year. The trade wind inversion, caused by subsidence aloft, also was an issue this year.
The remaining threat, which is what needs to be watched during October, or even into November, is development over the SE Gulf or NW Caribbean. If a storm forms there, it most likely will recurve and move NE towards the US / Florida. The Gulf of Mexico has not been "tapped" yet for heat content either. I still feel that if a storm forms in that region, there will be shear to disrupt it, so a storm like Wilma last year is unlikely, but not impossible.
Such storms would not devleop from tropical waves, but remnant vorticity associated with stalled frontal zones in the NW Caribbean / SE Gulf.
Now you are wondering about the NAO (North Atlantic Oscillation), the cyclic shift of the NA current in negativce cycle, beginning in 1995 which caused an upswing in hurricanes. Yes, it is still there, but other things are counteracting it (like El Nino). Remember in 1997 there was not many storms, because of El Nino, and 1995 there were 21 storms, both with a -NAO.
El Nino this year started to develop by July. Looking at the OTIS (US Navy Oceanography Fleet page FNMOC), the SST Anomaly already shows 2-3 degrees higher than normal off South America in the Pacific near the Equator, extending out into the ocean westward. A La Nina appears below normal, and is the opposite. El Nino becomes strongest around late December (Christmas), hence the spanish name for "Boy Child" or "Christ".
