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Atlantic Tropical Action 2011 - Part II


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The GFS continues to advertise vortisity passing the Windward Islands and into the S Caribbean. My hunch is that we'll be watching the Western Caribbean in about a week...

12Z GFS is semi-encouraging on potential Tropical Storm Steve Bret. Could it come close enough to Texas to rain on my lawn a la Dolly if it isn't a GFS figment?

post-138-0-75180800-1309969954.gif

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Someday, the NAM will be right. Someday. And the 576 dm thickness line wrapped around the NAM low suggests the NAM is forecasting warm core development.

You can't get TCG with 30-50 knots of westerly flow at 200mb. The NAM doesn't make physical sense, and it does this all the time with warm core systems in the Atlantic, spinning every little thunderstorm cluster into a tropical cyclone in the face of adverse upper level conditions.

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You can't get TCG with 30-50 knots of westerly flow at 200mb. The NAM doesn't make physical sense, and it does this all the time with warm core systems in the Atlantic, spinning every little thunderstorm cluster into a tropical cyclone in the face of adverse upper level conditions.

Um, you don't actually think I was defending the NAM's solution today, do you?

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Um, you don't actually think I was defending the NAM's solution today, do you?

I'm not saying you were, but the point is the NAM does this all the time, and it gets the weenies up in a tizzy. Ignore the NAM, and look at what the GFS shows in comparison. Even if the NAM ends up being partially correct in regards to development, generally there is excellent model support along with it so it is still useless since other models have a better handle on the situation. The GFS shows nothing more than a strong moisture fetch aiding to rainfall along the eastern seaboard.

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The Euro and GFS are on board with somewhat favorable conditions for that deep tropical TW east of the Windward islands right now. Their ensembles are favoring a rather deep West coast trough and another trough around the Labrador. This would favor ample ridging east of the Rockies by day 7+, which would translate to a threat (if TCG actually verifies) for TX/MX down the road. But it's still too early for details.

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:lol:

TROPICAL WEATHER OUTLOOK

NWS NATIONAL HURRICANE CENTER MIAMI FL

200 PM EDT WED JUL 6 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A LARGE BUT DISORGANIZED AREA OF CLOUDINESS AND THUNDERSTORMS OVER

THE SOUTHEASTERN GULF OF MEXICO...SOUTH FLORIDA...PORTIONS OF CUBA

AND THE BAHAMAS IS ASSOCIATED WITH A TROPICAL WAVE INTERACTING WITH

AN UPPER LOW. THIS ACTIVITY IS EXPECTED TO DRIFT NORTHWARD WITH NO

SIGNIFICANT DEVELOPMENT. THERE IS A LOW CHANCE...10 PERCENT...OF

THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE

NEXT 48 HOURS.

$$

FORECASTER AVILA

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I would watch the wave near 45W for the best long-term potential. Land interaction and unfavorable shear will keep this from developing much until it reaches the western Caribbean. Assuming the MJO forecasts are anywhere near correct, we should be under a favorable amplified phase 1-2. The best shot at TC genesis from this would be probably around the July 12-15 time frame, with the major caveats being that there's weak model support and this may not gain much latitude.

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I can understand it in longer ranges, but if its showing pretty much the same thing the euro is showing in a higher resolution, how is it useless?

Its just a question, not an attempt to prove anybody wrong.

:weenie:

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I can understand it in longer ranges, but if its showing pretty much the same thing the euro is showing in a higher resolution, how is it useless?

Its just a question, not an attempt to prove anybody wrong.

If it's showing pretty much the same thing, why would it be useful for?

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I can understand it in longer ranges, but if its showing pretty much the same thing the euro is showing in a higher resolution, how is it useless?

Its just a question, not an attempt to prove anybody wrong.

Because the model physics in it are tuned for continental, mid-latitude, baroclinic weather systems, not maritime, tropical, warm cored weather systems. It pools moisture in the low levels and the mid-levels are too cool, allowing for unrealistic values of conditional instability. That leads to overamplification and mostly worthless solutions. In order for a gridded (vs. spectral) model to be reasonable in the tropics, it needs to have nested grids to properly sample the inner core and allow the mass fields to stay in balance. Even then, we see how poorly the HWRF is at forecasting TCs and it uses similar physics to the NAM (though tuned to the tropics) at a better resolution with nested grids.

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