Tropical Storm Lorenzo

Update, October 24, 11 a.m. Eastern: Lorenzo “is barely hanging on to tropical cyclone status,” per the NHC this morning, and will probably be gone in the next 24 hours.

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Update, 11 a.m. Eastern: Lorenzo has an eye now, per the NHC this morning, but only in its upper level. Wind shear has offset this eye from the center of circulation.

On current GOES imagery, Lorenzo has a pretty swirl and is quite healthy. Its very thick and fluffy center indicates lots of convection, and the center of circulation is covered.
 
Lorenzo
 

Morphed integrated microwave imagery (MIMIC)dramatically shows how Lorenzo developed over the last 72 hours – it’s that rotating swirl west of the 50-degree longitude line:
 


 

MIMIC imagery is pretty cool, even to amateurs like me. Of course, it also contains a lot of information of use to scientists. A tropical cyclone, like other weather systems, is constantly changing. MIMIC gives the experts a better idea of how an individual storm develops and moves.

Here is close-up of Lorenzo over the last 12 hours. Can you see the upper level eye and how it’s displaced over the center of circulation? It takes a little while, for the untrained eye, but both are there.
 

Source.

Source. You may have to click the image to get it to start running.


 

This imagery also shows that, despite its healthy-looking appearance on visible satellite views, Lorenzo is beginning to struggle for maintenance – the red colors are intense at first but have disappeared by the end of the animation.

We likely will see this tropical storm weakening soon.

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Well, this is a surprise!

The National Hurricane Center had an area of interest out in the Atlantic north of Bermuda that they upgraded to a tropical depression this morning, and now they have categorized it as Tropical Storm Lorenzo.

The GFS doesn’t strengthen this much at all, and I didn’t think the NHC would go for it. However, its satellite appearance right now does look too impressive for a tropical depression:

That's not an eye.  The center of circulation may be getting covered (see NHC discussion, below) - a sign of strengthening.  (GOES)

That’s not an eye. The center of circulation may be getting covered (see NHC discussion, below) – a sign of strengthening. (GOES)

Very nice outflow and lots of convection, it appears to this amateur. It’s truly “the little invest that could.”

Here is what the NHC had to say about Lorenzo about 2-1/2 hours ago:

THE SATELLITE PRESENTATION OF THE CYCLONE HAS BECOME BETTER ORGANIZED SINCE THIS MORNING. A CURVED BAND CONSISTING OF COLD-TOPPED CONVECTION HAS LENGTHENED AND BECOME BETTER DEFINED…EVEN THOUGH THE LOW-LEVEL CENTER OF THE CYCLONE IS EXPOSED AT THE WESTERN TIP. IN ADDITION…A 1254 UTC ASCAT-A PASS HAD A COUPLE OF 34-KT WIND VECTORS EAST-SOUTHEAST OF THE CENTER. BASED ON THE EARLIER ASCAT PASS…THE DEPRESSION IS UPGRADED TO A TROPICAL STORM WITH AN INITIAL INTENSITY OF 35 KT.

THE ASCAT PASSES AND FIXES FROM VISIBLE SATELLITE IMAGERY TODAY HAVE ALLOWED FOR A BETTER ASSESSMENT OF THE INITIAL MOTION WHICH IS ESTIMATED TO BE 030/06…TO THE LEFT OF THE PREVIOUS ESTIMATE.

THE FORECAST PHILOSOPHY REMAINS THE SAME. LORENZO SHOULD BE STEERED NORTH-NORTHEASTWARD AND THEN NORTHEASTWARD DURING THE NEXT DAY OR SO AROUND THE NORTHWEST SIDE OF A MID-LEVEL RIDGE. AFTER THAT TIME…THE CYCLONE SHOULD TURN EAST-NORTHEASTWARD ALONG THE SOUTHERN EDGE
OF NEARLY ZONAL FLOW NEAR 30N. THE NHC TRACK FORECAST IS ADJUSTED SIGNIFICANTLY TO THE LEFT OF THE PREVIOUS ONE DUE TO A MORE NORTH-NORTHEASTERLY INITIAL MOTION…AND IS JUST AHEAD OF THE MULTI-MODEL CONSENSUS TO BETTER MATCH THE FASTER GFS/ECMWF SOLUTIONS.

SOME INTENSIFICATION IS EXPECTED DURING THE NEXT DAY OR SO WHILE THE CYCLONE IS OVER WARM WATERS AND IN THE DIFFLUENT FLOW EAST OF AN UPPER-LEVEL CYCLONIC SHEAR AXIS. BY 36HOURS…SHIPS OUTPUT SHOWS A CONSIDERABLE INCREASE IN WESTERLY VERTICAL WIND SHEAR THAT SHOULD RESULT IN A DECOUPLING OF THE CYCLONE IN 2 TO 3 DAYS. THE GUIDANCE SHOWS THE REMNANT CIRCULATION IS LIKELY TO DISSIPATE AHEAD OF AN APPROACHING BAROCLINIC ZONE IN 3 TO 4 DAYS. THE NHC INTENSITY FORECAST IS RAISED SLIGHTLY OVER THE PREVIOUS ONE…AND IS
GENERALLY NEAR THE MULTI-MODEL CONSENSUS BUT A BIT LOWER THAN THE SHIPS/LGEM OUTPUT.

FORECAST POSITIONS AND MAX WINDS

INIT 21/2100Z 28.9N 54.9W 35 KT 40 MPH
12H 22/0600Z 29.5N 53.9W 40 KT 45 MPH
24H 22/1800Z 29.9N 52.5W 45 KT 50 MPH
36H 23/0600Z 30.3N 51.1W 40 KT 45 MPH
48H 23/1800Z 30.9N 49.8W 35 KT 40 MPH
72H 24/1800Z 33.0N 46.5W 30 KT 35 MPH
96H 25/1800Z…DISSIPATED

$$
FORECASTER KIMBERLAIN

Again, in English, Lorenzo isn’t going to be with us long, and it certainly will not threaten any land.



Categories: Weather

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