ATL : TROPICAL DEPRESSION ERIKA (06L)

[curtadams]

To me this looks to be under intense NW mid shear. The Guadaloupe radar has a tilted tornado look, with the (weak and variable) tip near the visible center and a widening line going to the south, eventually spreading out into a very wide top (ie the way a hurricane is supposed to be organized). At all points I get the impression of things rotating around that line. This is very typical of sheared storms although it's pretty extreme. Convection is also weak towards the bottom which make me expect it to weaken in the future.

[Dave]

000
URNT15 KNHC 021748
AF309 0306A ERIKA HDOB 10 20090902
173830 1700N 06114W 9593 00430 0075 +233 +184 085019 019 026 001 00
173900 1659N 06113W 9596 00427 0075 +229 +184 083018 019 026 001 00
173930 1658N 06111W 9591 00431 0075 +230 +185 084018 019 026 000 00
174000 1657N 06110W 9595 00427 0074 +230 +185 087017 018 025 000 00
174030 1656N 06109W 9593 00429 0074 +230 +185 085015 016 027 000 00
174100 1655N 06108W 9597 00424 0074 +230 +186 082015 015 027 000 00
174130 1654N 06107W 9595 00426 0073 +231 +186 084014 014 027 000 00
174200 1653N 06106W 9593 00426 0072 +230 +186 081014 014 026 000 00
174230 1652N 06105W 9593 00427 0071 +234 +186 081014 014 027 000 00
174300 1651N 06104W 9596 00424 0071 +232 +186 082015 015 026 001 00
174330 1650N 06103W 9593 00427 0072 +231 +187 082015 015 026 000 00
174400 1649N 06102W 9590 00429 0072 +229 +188 081015 015 028 000 00
174430 1648N 06101W 9590 00428 0072 +230 +188 077014 015 028 000 03
174500 1647N 06059W 9593 00426 0071 +230 +188 078015 016 026 000 00
174530 1646N 06058W 9594 00425 0071 +229 +188 082014 014 027 000 00
174600 1645N 06057W 9593 00427 0072 +228 +188 084013 014 026 000 00
174630 1644N 06056W 9595 00424 0071 +228 +188 093010 012 028 000 03
174700 1642N 06055W 9592 00427 0071 +230 +188 110008 008 999 999 03
174730 1641N 06054W 9594 00425 0071 +230 +188 115008 008 028 000 03
174800 1640N 06053W 9593 00425 0070 +231 +188 116008 009 025 000 03
$$
;

[Air Force Met]

Looks like an outflow boundary too - all of the above makes for a weakening system:

http://www.ssd.noaa.gov/goes/flt/t2/vis-l.jpg

Thats' what we heard yesterday at about this same time.

Please...let's not revise history. Yesterday at this time everyone here was pretty sure it was going to get upgraded. It had good low level inflow...the center was getting closer to the convection and it was on the rise. Completely different situation than yesterday.

Yesterday you didn't have shearing in the mid-levels coming in from the west and the center wasn't so exposed. Yesterday at this time it didn't look like a weakening system...it looked like a system that was getting its act together. Today...it looks like a system that is falling apart. That doesn't mean it will...or that it won't change that trend in the next hour...but as of right now...Frank is right...its weakening.

[otowntiger]

The Canadians are jealous of the weather in Miami...

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2009090200&field=Sea+Level+Pressure&hour=Animation

What is the possibility of it strengthening that quickly off the southeast Florida coast?

[deltadog03]

Well, its gonna be relatively weak around that area, so we shall see. I think recurve chances has gone down considerably.

[Gustywind]

Looks like an outflow boundary too - all of the above makes for a weakening system:

http://www.ssd.noaa.gov/goes/flt/t2/vis-l.jpg

Yesterday when someone said she spat out 4 outflow boundaries, she exploded. Let's just watch

you're right good reasoning Ivanhater

[curtadams]

Re outflow boundaries:

My amateur impression is that outflow boundaries far from the central convection (like yesterday, at least what I saw) are not a sign of weakening and actually seem to be associated with strengthening. They just indicate secondary storms fading which is no big deal. Outflow boundaries coming from central convection (which I've seen today) *are* an indication of a weakening storm.

[hurricanefloyd5]

...ERIKA NEAR GUADELOUPE...

[wxman57]

Intermediate advisory has center at 16.2N/61.1W. That's on the eastern side of Guadeloupe and on the eastern side of that vortex just southwest of Guadeloupe. I don't see any rotation near that intermediate point. Perhaps the NHC is just inching the position westward toward the vortex for the next advisory? In that case, their track should be over or south of PR at 4pm CDT. I'd go south of PR now and into the southern DR.

[somethingfunny]

The thing about crossing the DR is that this thing is so disorganized it wouldn't be a huge leap of faith to imagine another center reformation off the coast, bypassing the usual TC-crosses-Hispaniola-and-dies scenario. Still I'm not sure that re-organization will be so quick post-Hispaniola as the GFDL is forecasting. The CMC is initializing Erika well to the northeast of Guadeloupe as opposed to its' current location so it's not taking Hispaniola's impact into account at all when it portrays that RI scenario near Florida.

[Aric Dunn]

Intermediate advisory has center at 16.2N/61.1W. That's on the eastern side of Guadeloupe and on the eastern side of that vortex just southwest of Guadeloupe. I don't see any rotation near that intermediate point. Perhaps the NHC is just inching the position westward toward the vortex for the next advisory? In that case, their track should be over or south of PR at 4pm CDT. I'd go south of PR now and into the southern DR.

still the mean center (centroid) .. there is probably very weak rotation east still but it looks to be weakening..

[wxman57]

Here's a plot showing the NHC 18Z point and the vortex center:

[Dave]

URNT15 KNHC 021758
AF309 0306A ERIKA HDOB 11 20090902
174830 1639N 06052W 9597 00450 0081 +230 +189 114007 007 023 001 00
174900 1638N 06051W 9591 00427 0070 +231 +189 131005 005 025 000 00
174930 1637N 06049W 9599 00448 0089 +233 +189 148005 006 025 000 00
175000 1636N 06048W 9594 00423 0081 +233 +190 157005 006 026 000 00
175030 1635N 06047W 9590 00427 0071 +229 +191 166006 007 023 001 00
175100 1634N 06046W 9597 00449 0087 +230 +190 193006 006 025 000 00
175130 1633N 06045W 9593 00423 0069 +230 +189 205007 007 025 000 03
175200 1632N 06044W 9590 00426 0082 +230 +189 210007 008 026 000 00
175230 1631N 06043W 9594 00423 0069 +230 +189 218007 008 027 000 00
175300 1630N 06042W 9594 00423 0074 +232 +189 222010 010 025 000 00
175330 1628N 06040W 9594 00423 0077 +235 +190 217012 012 024 000 00
175400 1627N 06039W 9593 00424 0071 +232 +190 218013 014 024 000 00
175430 1626N 06038W 9594 00423 0069 +230 +190 223013 014 026 000 00
175500 1625N 06037W 9594 00424 0070 +230 +190 225014 014 026 000 00
175530 1624N 06036W 9594 00424 0070 +230 +191 224015 015 026 000 00
175600 1623N 06035W 9594 00424 0070 +230 +190 220014 014 026 000 00
175630 1622N 06034W 9594 00426 0071 +230 +190 218014 014 026 000 00
175700 1621N 06032W 9593 00425 0071 +230 +190 220014 014 025 000 00
175730 1620N 06031W 9593 00425 0071 +230 +190 221014 014 027 000 00
175800 1618N 06030W 9594 00424 0071 +230 +189 217014 015 026 000 00
$$
;

[HURAKAN]

[somethingfunny]

Re outflow boundaries:

My amateur impression is that outflow boundaries far from the central convection (like yesterday, at least what I saw) are not a sign of weakening and actually seem to be associated with strengthening. They just indicate secondary storms fading which is no big deal. Outflow boundaries coming from central convection (which I've seen today) *are* an indication of a weakening storm.

This outflow boundary is actually radiating from the convection at a perpendicular angle to the LLC. That's one ugly storm at present.

[Brent]

BULLETIN
TROPICAL STORM ERIKA INTERMEDIATE ADVISORY NUMBER 4A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062009
200 PM AST WED SEP 02 2009

...ERIKA NEAR GUADELOUPE...

A TROPICAL STORM WARNING REMAINS IN EFFECT FOR GUADELOUPE...ST.
MARTIN...ST. BARTHELEMY...ANTIGUA...BARBUDA...MONTSERRAT...ST.
KITTS...NEVIS...ANGUILLA...ST. MAARTEN...SABA...AND ST. EUSTATIUS.

INTERESTS ELSEWHERE IN THE LEEWARD ISLANDS...THE U.S. AND BRITISH
VIRGIN ISLANDS...AND PUERTO RICO SHOULD MONITOR THE PROGRESS OF
ERIKA. TROPICAL STORM WATCHES OR WARNINGS COULD BE REQUIRED FOR A
PORTION OF THESE AREAS LATER TODAY.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA
OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR NATIONAL METEOROLOGICAL SERVICE.

AT 200 PM AST...1800 UTC....THE CENTER OF THE POORLY ORGANIZED
TROPICAL STORM WAS ESTIMATED TO BE NEAR LATITUDE 16.2 NORTH...
LONGITUDE 61.1 WEST OR VERY NEAR GUADELOUPE IN THE LEEWARD ISLANDS.

ERIKA IS MOVING TOWARD THE WEST NEAR 10 MPH...17 KM/HR. A WEST-
NORTHWESTWARD MOTION IS EXPECTED TO BEGIN LATER TODAY. ON THE
FORECAST TRACK...ERIKA WILL BE MOVING THROUGH THE LEEWARD ISLANDS
TONIGHT AND TOMORROW.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 40 MPH...65 KM/HR...WITH HIGHER
GUSTS. HOWEVER...SATELLITE IMAGES INDICATE THE STORM MAY BE
WEAKENING. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS
CURRENTLY EN ROUTE TO DETERMINE THE INTENSITY OF ERIKA. LITTLE
CHANGE IN STRENGTH IS FORECAST TODAY WITH SOME SLIGHT
RESTRENGTHENING POSSIBLE TOMORROW.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 105 MILES...165 KM
MAINLY WELL TO THE EAST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.

ERIKA IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 2 TO 4
INCHES OVER MUCH OF THE LESSER ANTILLES DURING THE NEXT COUPLE OF
DAYS...WITH ISOLATED MAXIMUM AMOUNTS OF 6 INCHES POSSIBLE. OVER
PUERTO RICO...3 TO 5 INCHES OF RAIN ARE POSSIBLE DURING THE NEXT
FEW DAYS...WITH ISOLATED MAXIMUM AMOUNTS OF 8 INCHES.

...SUMMARY OF 200 PM AST INFORMATION...
LOCATION...16.2N 61.1W
MAXIMUM SUSTAINED WINDS...40 MPH
PRESENT MOVEMENT...WEST OR 265 DEGREES AT 10 MPH
MINIMUM CENTRAL PRESSURE...1008 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 PM AST.

$$
FORECASTER BLAKE/FRANKLIN

[HURAKAN]

[Aric Dunn]

12z cmc.. straight west..

then dissipates.. it

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

[HURAKAN]

East of Guadaloupe

[Frank2]

Per the 2 p.m. advisory:

MAXIMUM SUSTAINED WINDS REMAIN NEAR 40 MPH...65 KM/HR...WITH HIGHER
GUSTS. HOWEVER...SATELLITE IMAGES INDICATE THE STORM MAY BE
WEAKENING. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS
CURRENTLY EN ROUTE TO DETERMINE THE INTENSITY OF ERIKA. LITTLE
CHANGE IN STRENGTH IS FORECAST TODAY WITH SOME SLIGHT
RESTRENGTHENING POSSIBLE TOMORROW.

P.S. Thanks Air Force Met - from my daily experience with CARCAH (Col. Hairston, long retired), the CARCAH folks were always good to work for at the NHC when it came to really having a practical grip on whether a system was weakening or strengthening (sometimes better than our own folks)...