East Coast Troughs

[Frank2]

Not to start in so early (LOL), but, I've noticed the ongoing pattern of very deep east coast troughs (or, at least deep troughs between the Mississippi and the east coast), over the past month - this seems to be a long-wave pattern, so, something that is not likely to change quickly...

This also seems connected to the very cold and snowy winter the upper midwest experienced this winter now past, so, perhaps it's a pattern that has been in place for a number of months (considering the cold temps in the upper midwest today, there seems to be little overall change)...

If this pattern continues, you have to wonder how it will affect the season, since that would mean less than favorable conditions for tropical cyclone formation...

[Derek Ortt]

we had a storng east coast trough in Aug 2004

asll it did was send 3 different canes into the Carolinas and one fo them, also devastated Cuba and Florida.

The pattern changed for September to a long wave ridge.

I think there is enough time for a change by the heart of the hurricane season, though if it persists, the threat may shift to the NE/Canada and extreme S Florida (from the Caribbean)

[george_r_1961]

we had a storng east coast trough in Aug 2004

asll it did was send 3 different canes into the Carolinas and one fo them, also devastated Cuba and Florida.

The pattern changed for September to a long wave ridge.

I think there is enough time for a change by the heart of the hurricane season, though if it persists, the threat may shift to the NE/Canada and extreme S Florida (from the Caribbean)

Exactly. What effect a trough has on a tropical cyclone depends on how its tilted. A NW/SE oriented trough from Ohio to NC would be like a hurricane magnet for the SE and mid atlantic.

[Rainband]

Way to early to even start guessing. lets just hope it's quiet around here. Anyone who wants them can have them. Keep them out of the GOM.

[Frank2]

The past troughs don't seem to be tilted one way or another, just fairly deep (but not deep enough to give Florida a cold Winter - we just barely had one significant cold snap)...

I agree with rainband - considering the price of gasoline, let us pray that we don't see any Gulf systems of consequence this season...

[Frank2]

On the cool side this morning in South Florida (48 in Tallahassee this morning) - the troughiness continues in the east, and, as mentioned earlier, this has been part of a long-wave pattern - we'll see if it continues into the summer and if it has an effect on the hurricane season...

[gatorcane]

Frank NWS Miami mentions a Rex Block over the Western half of the North America and an unseasonably strong Low pressure system to develop over the Great Lakes by the weekend. This combination will shoot the temperatures over Southeast Florida into at least the mid 90s by this weekend on the heals of a dominant SW low to mid-level windflow possibly breaking records yet again. This pattern will do nothing to help the fires over east-central florida. I do not expect this troughiness to dominate the long-wave pattern throughout the duration of the hurricane season. Whenever I see a Rex Block like this, I typically see the long-wave pattern shift, to strong ridging in the eastern half of the CONUS, just when this will happen is the question though.

[TreasureIslandFLGal]

The "troughiness" we are seeing now is not so out of the ordinary. In fact, it is part of the yearly pattern we always see.

During hurricane season, we see the bermuda high dominant in the southwest atlantic and its placement shifts into the conus or futher out into the atlantic back and forth throughout the storm season. Near the end of the season, we start to see the pattern shifting to the more frequent affects of troughs that dip low, often causing the ubrupt redirecting of storms that were following the periphery of the bermuda high, or assisting to "pull" carribean storms northward and northeastward up into the weakness they create ahead of them.

Eventually, as late fall comes, they become so strong and frequent that few, if any, storms can even make it across the atlantic or close to conus because the fronts redirect everything out to sea. Eventually the bermuda high displaces towards the east, well off the coast of the US. It then seems to dissipate or merge with the Azores high until the next summer/late spring. That is the seasonal pattern.

Which is where we are now in the southeast... the "winter time" troughs are becoming less frequent to dip so far south at this time of year, so we are noticing them more when they do. Very soon, their passing will be a thing of months past, as few will venture this far south, preferring instead to tread along more northerly paths, as if they prefer to go around the developing bermuda high that will soon once again set itself up just off our southeast coast. (They actually follow the pattern of the jet stream which tends to go up and to the north of the bermuda high.)

Where the bermuda high actually centers itself becomes the most influential factor in where cape verde storms will eventually hit the US. If it centers itself further to the east, then its western periphery will be off the US East coast. Approaching storms will travel around it and be more likely to track towards the Carolinas and to points north. If it slots itself very close to the east coast, then: "look out Florida!" If it oozes over Florida and into the gulf, then the gulf coast and Texas have to watch out.

Come the fall, when the frequent troughs return, Texas and the western gulf states feel safer, since odds are that a trough will "block and protect" them from any approaching storms, making them unable to make a beeline for their coasts.

West coast Florida has to increase vigilance in the early season or late season when lots of troughs are around, since the troughs are the best chance for a direct hit for them, as usually only a trough can cause a storm to recurve or travel in a northeasterly direction. Well, not the "only" way, as gulf storms can meander aimlessly in just about any direction when traveling at 6 knots or less! (loop di-loops are common too!) -but fronts do make it dicier for west coast Floridians...i.e. Charley

OK, there is my little course on Troughs and the Bermuda High 101.

[Blown Away]

Seems the experts are expecting more persistent troughs this year, thus the Carolina's North activity predictions.