ATL : TROPICAL DEPRESSION ERIKA (06L)

[cycloneye]

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TROPICAL STORM ERIKA DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062009
1100 PM AST WED SEP 02 2009

ERIKA IS BARELY A TROPICAL STORM. DATA FROM A RECONNAISSANCE PLANE A
FEW HOURS AGO AND OBSERVATIONS FROM THE LESSER ANTILLES INDICATE
THAT ERIKA IS VERY DISORGANIZED AND CONSISTS OF A BROAD ELONGATED
CYCLONIC CIRCULATION WITH TROPICAL STORM FORCE WINDS IN
SQUALLS...LIMITED TO A FEW SPOTS OVER THE EASTERN SEMICIRCLE. A NEW
CENTER COULD REFORM AT ANY TIME WITHIN THE LARGE GYRE. INFRARED
PICTURES SUGGEST THAT THERE IS UPPER-LEVEL OUTFLOW IN ALL
QUADRANTS...BUT THERE IS ALSO SHEAR CAUSED BY WINDS BELOW THE
CIRRUS CANOPY BECAUSE THE CENTER CONTINUES TO BE LOCATED ON THE
WESTERN EDGE OF A STRONG AREA OF CONVECTION. IT APPEARS THAT ERIKA
IS ON ITS WAY TO DEGENERATE INTO A TROUGH OF LOW PRESSURE OR REFORM
SOMEWHERE WITHIN THE CIRCULATION. GLOBAL MODELS ARE FORECASTING A
LITTLE MORE FAVORABLE ENVIRONMENT IN 12 TO 24 HOURS AND THAT IS THE
REASON THE OFFICIAL FORECAST CALLS FOR NO CHANGE IN INTENSITY
DURING THE NEXT 12 HOURS. THEREAFTER...THE COMBINATION OF VERY
HOSTILE UPPER-LEVEL WESTERLIES AND THE LAND MASS OF HISPANIOLA
ALONG THE PATH OF THE CYCLONE...WOULD RESULT IN WEAKENING. THE HWRF
IS THE ONLY MODEL THAT FORECAST ERIKA TO BECOME A STRONG HURRICANE
AND THIS IS HIGHLY UNLIKELY TO OCCUR.

THE CENTER OF THE LARGE CIRCULATION ENVELOPE HAS BEEN MOVING
WESTWARD AT 7 KNOTS. THE CYCLONE SHOULD BE STEERED TOWARD THE
WEST-NORTHWEST DURING THE NEXT FEW DAYS AROUND THE SUBTROPICAL
RIDGE WHICH IS FORECAST TO BUILD WESTWARD BY THE GLOBAL MODELS.
THE TRACK GUIDANCE IS LIMITED SINCE VARIOUS MODELS WEAKEN THE
CYCLONE WITH TIME AND THE TRACKERS NO LONGER FOLLOW THE CENTER.
HOWEVER...THE AVAILABLE CONSENSUS ALSO SUGGESTS THAT ERIKA OR ITS
REMNANTS SHOULD MOVE TOWARD THE WEST-NORTHWEST UNTIL DISSIPATION
AND SO DOES THE OFFICIAL FORECAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL 03/0300Z 16.1N 62.4W 35 KT
12HR VT 03/1200Z 16.4N 63.8W 35 KT
24HR VT 04/0000Z 17.0N 65.5W 30 KT
36HR VT 04/1200Z 18.0N 67.0W 30 KT
48HR VT 05/0000Z 18.5N 68.5W 30 KT...INLAND
72HR VT 06/0000Z 20.0N 71.0W 25 KT...REMNANT LOW
96HR VT 07/0000Z 22.0N 73.0W 20 KT...REMNANT LOW
120HR VT 08/0000Z...DISSIPATED

[HURAKAN]

There's an 850 mb center near Barbuda? That's pretty darn close to the surface, is it not, about a mile? I'd be interested to see what recon finds tonight, if any flights are scheduled.

FLIGHT TWO - TEAL 75......NO CHANGE
A. 03/0600Z, 1200Z
B. AFXXX 0406A CYCLONE
C. 03/0445Z
D. 18.5N 62.2W
E. 03/0530Z TO 03/1200Z
F. SFC TO 10,000 FT


Bad guess in latitude!!!

[Gustywind]

[canes04]

per 11pm disc. a new center can form at anytime.
I think this will happen overnight in the 17n 60.5w area.

time to sleep.

[wxman57]

wxman, look at on this shortwave loop. To the northeast of all the convection. http://www.ssd.noaa.gov/goes/flt/t2/loop-ir2.html

Just an area of squalls. I'm looking at surface observations in the area. Winds west of the squalls are out of the southeast. So nothing at the surface there. This really looks like a wave now.

[artist]

Tidbits from tonight's discussion:

ERIKA IS BARELY A TROPICAL STORM. DATA FROM A RECONNAISSANCE PLANE A
FEW HOURS AGO AND OBSERVATIONS FROM THE LESSER ANTILLES INDICATE
THAT ERIKA IS VERY DISORGANIZED AND CONSISTS OF A BROAD ELONGATED
CYCLONIC CIRCULATION WITH TROPICAL STORM FORCE WINDS IN
SQUALLS...LIMITED TO A FEW SPOTS OVER THE EASTERN SEMICIRCLE. A NEW
CENTER COULD REFORM AT ANY TIME WITHIN THE LARGE GYRE. INFRARED
PICTURES SUGGEST THAT THERE IS UPPER-LEVEL OUTFLOW IN ALL
QUADRANTS...BUT THERE IS ALSO SHEAR CAUSED BY WINDS BELOW THE
CIRRUS CANOPY BECAUSE THE CENTER CONTINUES TO BE LOCATED ON THE
WESTERN EDGE OF A STRONG AREA OF CONVECTION. IT APPEARS THAT ERIKA
IS ON ITS WAY TO DEGENERATE INTO A TROUGH OF LOW PRESSURE OR REFORM
SOMEWHERE WITHIN THE CIRCULATION.

gyre -

An oceanic gyre is any large-scale system of rotating ocean currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis effect; planetary vorticity along with horizontal and vertical friction, which determine the circulation patterns from the wind curl (torque).[1]

The term gyre can be used to refer to any type of vortex in the air or the sea, even one that is man-made, but it is most commonly used to refer to the major ocean systems.
Tropical circulations
Tropical circulations are less unified and tend to be mostly east-west with minor north-south extent.

Atlantic Equatorial Current System (two counter-rotating circulations)

[Bocadude85]

wxman, look at on this shortwave loop. To the northeast of all the convection. http://www.ssd.noaa.gov/goes/flt/t2/loop-ir2.html

Just an area of squalls. I'm looking at surface observations in the area. Winds west of the squalls are out of the southeast. So nothing at the surface there. This really looks like a wave now.

Agree looks like a open wave

[Evil Jeremy]

wxman, look at on this shortwave loop. To the northeast of all the convection. http://www.ssd.noaa.gov/goes/flt/t2/loop-ir2.html

Just an area of squalls. I'm looking at surface observations in the area. Winds west of the squalls are out of the southeast. So nothing at the surface there. This really looks like a wave now.

Agree looks like a open wave

I also agree. But then again, looks can be deceiving. Ugh, I hate this hurricane season, its too confusing lol!

[deltadog03]

"of course, if the center reforms to the north, it puts the storm out of the worst mid level shear and it could intensify and head toward Puerto Rico"

I agree Derek, the mid shear is nothing north of the islands compared to south of them. North of the islands is running in the 5-10kt range, not 25-30kt south of them. I still think we will see something get together with that new burst up in NW quad.

[artist]

has the pacific season been as unusual as the atlantic seems to be to me?

[HURAKAN]

The only thing I know is that tomorrow we will know what Erika will do. Today we're just guessing!!!

[Macrocane]

has the pacific season been as unusual as the atlantic seems to be to me?

The CPAC storms have been very confusing, but the EPAC has been fairly active and normal IMO except for the very late start.

[fd122]

Some mild thunder and lightning has began here in Antigua.

[Evil Jeremy]

Starting to look like the new "blob" to the NE of the center is taking over: http://www.ssd.noaa.gov/goes/flt/t2/loop-wv.html

[deltadog03]

I wouldn't be suprised if we something close to the SFC when recon gets in there...I am talking about the new blowup on the NW side of this. (just north of island) Mid shear is down to around 10kts up there.

[AtlanticWind]

It would be something if the HWRF was even half right

http://www.ssd.noaa.gov/goes/east/carb/rb-l.jpg

[JonathanBelles]

How often do TC's undergo Mitosis? (for the lack of a better word)

[Evil Jeremy]

I wouldn't be suprised if we something close to the SFC when recon gets in there...I am talking about the new blowup on the NW side of this. (just north of island) Mid shear is down to around 10kts up there.

I am a little braindead right now lol, so I take it SFC means surface?

[Sanibel]

GFDL is south of Cuba (ut oh).

[deltadog03]

ya...Surface