US Weather Commentary

Location: New York
Author: Weather 2000, Inc.
Date: Thursday, September 20, 2007
 

FYI: This is not the wave in the Eastern Atlantic some models were pointing to the past seven days; this is not the disturbance in the Central Caribbean that some models were pointing to the past seven days; this is not the convection in the Southwestern Caribbean that some models were pointing to the past seven days;  this is not the re-generation of Ingrid that some services were hoping for.

WHAT/WHERE: Rather this is the good ol' fashioned stationary front tail we were monitoring off of the Jacksonville FL coast, which are always dangerous breeding grounds as per our yearly warning: {If your main concern is Tropical Storm/Hurricane threats to the U.S. (within 72 hours after classification), our focus is formation regions much closer to home (examples this year include every storm that struck the U.S.: Barry, Erin, Gabrielle and Humbeto; and historic/extreme examples of which in the past half-Century: include Rita, Katrina, Jeanne, Camille, Gracie, and Carol). Stationary fronts, tails of surface troughs, costal Lows (and their subsequent meso-vorticity centers) near North America are ideal nurseries for tropical cyclone development at any time.  These areas grab our attention more, because they are (1.) a hop, skip and a jump away from U.S. (or associated Gulfs & Straits), (2.) can form almost regardless of whether Atlantic basin-wide conditions are favorable or not (SST's, Shear, MJO, etc.), and (3.) often have erratic or looped motions which can drastically shift landfall warnings or rapidly intensify in a matter of hours}. 

WHEN:  The surface Low Pressure area is currently weak, broad, disorganized and interacting with Florida, so an official Advisory of (Sub)Tropical Depression #10 and/or (Sub)Tropical Storm JERRY from NHC wouldn't happen until later this week. Keep in mind that the NHC has a disproportionate tendency to classify tropical storms (especially those near North America) on either Weekday Evenings (after 4 PM ET), or on Weekends.  You'll always hear from us first when a legitimate tropical entity is imminently about to be classified, and before an official classification hits public weather & news wires.

HOW: This mass of thunderstorms & convection (whether classified or not) should slowly trek westward, across the Florida Peninsula, and into the Northeastern Gulf of Mexico before imbedding itself (landfall) along the Gulf Coast thereafter. Sea Surface Temperatures are extremely warm across the Eastern GOM (90°F off Florida's West Coast and 85°F further West), so intensification is probable (and perhaps surprisingly so as Humberto recently demonstrated).  The Continental Shelf is broader than where Humberto was and the Oceanic Heat content is not that high in the Eastern GOM, so if this system stalls or dilly-dallies it will churn up its own cool water up-welling.

WHY: Unlike Katrina which did a Florida traverse in a similar vicinity, but drifted South and kept postponing her Northward curvature, this system is more Sub-Tropical in nature.  Whether NHC decides to officially declare this system a SUB-TROPICAL Depression/Storm is another story, but nonetheless it will initially be garnering some of it its energy from baroCLINIC processes & zones.  What this means is that the system will want to follow the cool air/warm air gradients which are further North than models indicated (i.e. towards the deep South U.S. as opposed to towards the South-Central Gulf of Mexico).

WHO: Some weather folks also jumped on yesterday's model runs (depicting South Texas/Mexico strikes), not realizing these models were initialized way too far South to begin with. Sub-Tropical entities are also heavily influenced by the steering currents of warm-core ridges (which we have over the Eastern U.S.), which will assist in an eventual curvature/Northwest vector, as opposed to the pure East-to-West path others have been depicting.

Of course, National TV weatherpeople have already been dispatched to Florida to cover every cloud & lightning flash & wind gust from what is merely a collection of thunderstorms.  But this system ain't doing anything until it gets its act together (symmetrical organization) and moves away from/beyond Florida.  It all comes down to the location, vector and upper-air environment (i.e. paired with low pressure or high pressure aloft) at which the system "exits" Florida, so speculation about specific model scenarios is an exercise in futility at this point.

All maritime and land interests across Florida, the Gulf of Mexico and Gulf Coast should pay attention to further developments, and please contact us should you have questions that have not been answered by our commentaries and advisories.

Re-included from previous discussions for pertinence:

Tropical Storms don't form because computer models say they will, they form when hydro-meteorological, fluid-dynamic and thermodynamic conditions are ripe and conducive. There has been hyperactive drum-beating in 2007 surrounding what this model or that model says, and the subsequent 90 percent False Alarm Rates unfortunately get swept under the rug.  More troubling is that some weather folks have learned that Tropical Storm fears garner the greatest user reaction and media headlines, so they will keep quiet about models when preoccupied with other matters, but then arbitrarily point to models (which always spin up Tropical Storms) when they want some attention.  This hurts the science and also hurts the users who genuinely need to know when legitimate threats arise without being enshrouded in a crying-wolf fog.

You take [the most active month of the Hurricane Season/September] + [an emerging La Niña] + [warm ocean waters] + [positive MJO phase] + [wait a week or so] = Tropical Storm formation!  You don't need computer models to predict that no-brainer.  From the equation above, MJO conditions and regional shear have been pretty inhospitable which is why new Tropical Storms never materialized as they were rumored to on Thursday or Friday or the Weekend or Monday or Today, or...(you get the picture).  These conditions should slowly improve later this week (but still nothing great), and when they do, that is when we'll examine the physics (not the models) for potential candidates that might emerge.

Tropics References:

• NOTE: Only about five percent of "entities" that computer models predict to become Tropical Storms actually do so.  Only about 10 percent of Tropical Waves off of Africa become Tropical Storms.  Only about 30 percent of Tropical Disturbances/Waves that NHC gives an "INVEST" designation, actually become Tropical Storms.
• DEAN and FELIX accounted for the first time in Atlantic Basin recorded history that two Category five Hurricane Landfalls occurred in the same year (let alone only two weeks apart)
• FELIX was the most rapidly intensifying Tropical Cyclone ever recorded in the World, jumping from Tropical Depression strength to Category five Hurricane Strength in only 42 Hours.

In addition to our normal forecast discussions, outlooks and advisories which you receive, you may also want to visit our Tropical Weather Page, to keep up to speed with the status of the Atlantic Hurricane Season, and other useful reference info:

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