ATL: ERNESTO - Post-Tropical

[ozonepete]

Looks like it'll be a tight little core.

http://rammb.cira.colostate.edu/product ... 312015.GIF

yep, LLC slightly NW of the convection. Detaching from the ITCZ...IMO this is a TD. It wouldnt take much to stack this but it looks like its out running the convection. Also has a wnw jog in that clip....

Nice analysis. I saw that WNW jog as well.

[cycloneye]

TCFA posted

http://www.nrlmry.navy.mil/atcf_web/ima ... 080112.gif

Here is the text of the TCFA.

KNGU 011430
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 10.8N 47.0W TO 11.2N 53.0W
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 20 TO 30 KNOTS. METSAT IM-
AGERY AT 011315Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 10.8N 47.0W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 15
KNOTS.
2. REMARKS:
CURRENT MODEL GUIDANCE IS DEPICTING INTENSIFICATION OF A TROPICAL
WAVE LOCATED ABOUT 870NM EAST OF THE SOUTHERN WINDWARD ISLANDS.
AT 011315Z, VISIBLE SATELLITE IMAGERY INDICATED AN AREA OF SCAT-
TERED MODERATE/STRONG CONVECTION THAT HAS PERSISTED OVER THE LAST
24 HOURS. WARM SEA SURFACE TEMPERATURES OF 82 TO 84 DEGREES
FAHRENHEIT IN CONJUNCTION WITH A FAVORABLE UPPER AIR ENVIRONMENT
MAY ENHANCE DEVELOPMENT OF THIS SYSTEM INTO A TROPICAL CYCLONE.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 021430Z.//

[MGC]

Sure does look to me that a surface circulation has formed between 11 and 12 degrees north with the convection displaced to the south.....much better organized today....the mid level circulation is not as elliptical looking as yesterday but more circular. I agree with 57...no upgrade to TD until recon gets to the system.....MGC

Of course the above is the opinion of MGC and not an official forecast.

[MiamiensisWx]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

First, I know I have been away forever, but now that there is finally something that might generate rain in parched South Florida, I will pipe up.

For the past few days, I have been highly skeptical as to the development of this low. In large part, much of this was due to the large upper-level low (TUTT), currently near 27°N 45°W, whose axis the GFS and its ensembles in particular show digging at least 3° farther south over the next three days. The GFS models have generally handled well the highly retrogressive, split-flow jet pattern that has dominated the Northwestern Hemisphere for the past several weeks. I have given these models more weight than the ECMWF, which shows, and has been showing consistently, a weaker TUTT and, within the first 60 hours, a stronger 99L, which it takes through Puerto Rico in about three days. While the cloud pattern of the system itself has become much better organized, and the low-level inflow/circulation more vigorous and tighter, in the last 24 hours, satellite overlays show that there is a very narrow slot of light net shear (15-kt low-level winds, 20-kt mid-level, 25-kt upper-level currently) over the system, and that much stronger vertical shear over 50 knots exists barely 2° north of the developing low-level center, which seems to be near 13°N 58°W at this time. Unless the 24-hour movement near 280° (WNW) changes, the system will be encountering much stronger shear in a little over 24 hours. Compared to its appearance overnight, the developing center appears much more exposed due to westerly shear on the north side of the system (note the contrast to the strong convection south of the center of circulation).

I briefly examined available climatology concerning systems that formed between August 1—15 within 90 n mi of the current position. For seasons with weak El Niño present by mid-August, as the current Pacific warming is on track to be, out of about 10 samples, I could not find any system on the current trajectory that developed, save Dennis of 1981, which went on to hit South Florida. Given the likelihood that shear will halt further substantial organization and result in an exposed center in about 24 hours, and given the strong ridge building in two days afterward, such a northward track seems unlikely. So that leaves no possible precedent for a TC in this area, at this time and in this type of season...and none for this type of system in a season that saw significant early-season, generally northward-tracking development outside of the deep tropics, as was witnessed earlier this year due to Alberto, Beryl, Chris, and Debby. Given the strong basis in climatology against both a northward track and any real development, the intensity models that take the system to hurricane intensity seem dubious, especially since they have had a stronger bias in the short term, just as the ECMWF and non-GFS models have consistently shown a northward bias with respect to the track over the past few days.

In short, I expect a maximum intensity of no more than 35 kt/40 mph and a track through the northern Windward Islands as a weak tropical storm in 48 hours. Thereafter, a track north of the latitude of Kingston, Jamaica, is not to be expected.

[ozonepete]

Interesting situation since there is a tongue of pretty high shear just to the north that it's passing under now. So any jogs it makes to the WNW will cause the convection to get clipped somewhat on the northern side, which is happening now. This makes me think it will probably be fighting to maintain decent symmetry for the rest of today. After that the shear looks to really drop and it should be able to ramp up more noticeably late tonight and tomorrow.

Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[wxman57]

Circulation (weak) is becoming easier to see as some of the convection near it diminished in the past hour. Could well be a TD tomorrow afternoon and weak TS by Friday morning. Don't see anything to drive it north of the Caribbean toward FL or the East U.S. Coast. Could well track west into Nicaragua/Honduras or Belize if it survives that long. Too early to determine if it will be a threat to the northern Gulf.

[MiamiensisWx]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

First, I know I have been away forever, but now that there is finally something that might generate rain in parched South Florida, I will pipe up.

For the past few days, I have been highly skeptical as to the development of this low. In large part, much of this was due to the large upper-level low (TUTT), currently near 27°N 45°W, whose axis the GFS and its ensembles in particular show digging at least 3° farther south over the next three days. The GFS models have generally handled well the highly retrogressive, split-flow jet pattern that has dominated the Northwestern Hemisphere for the past several weeks. I have given these models more weight than the ECMWF, which shows, and has been showing consistently, a weaker TUTT and, within the first 60 hours, a stronger 99L, which it takes through Puerto Rico in about three days. While the cloud pattern of the system itself has become much better organized, and the low-level inflow/circulation more vigorous and tighter, in the last 24 hours, satellite overlays show that there is a very narrow slot of light net shear (15-kt low-level winds, 20-kt mid-level, 25-kt upper-level currently) over the system, and that much stronger vertical shear over 50 knots exists barely 2° north of the developing low-level center, which seems to be near 13°N 58°W at this time. Unless the 24-hour movement near 280° (WNW) changes, the system will be encountering much stronger shear in a little over 24 hours. Compared to its appearance overnight, the developing center appears much more exposed due to westerly shear on the north side of the system (note the contrast to the strong convection south of the center of circulation).

I briefly examined available climatology concerning systems that formed between August 1—15 within 90 n mi of the current position. For seasons with weak El Niño present by mid-August, as the current Pacific warming is on track to be, out of about 10 samples, I could not find any system on the current trajectory that developed, save Dennis of 1981, which went on to hit South Florida. Given the likelihood that shear will halt further substantial organization and result in an exposed center in about 24 hours, and given the strong ridge building in two days afterward, such a northward track seems unlikely. So that leaves no possible precedent for a TC in this area, at this time and in this type of season...and none for this type of system in a season that saw significant early-season, generally northward-tracking development outside of the deep tropics, as was witnessed earlier this year due to Alberto, Beryl, Chris, and Debby. Given the strong basis in climatology against both a northward track and any real development, the intensity models that take the system to hurricane intensity seem dubious, especially since they have had a stronger bias in the short term, just as the ECMWF and non-GFS models have consistently shown a northward bias with respect to the track over the past few days.

In short, I expect a maximum intensity of no more than 35 kt/40 mph and a track through the northern Windward Islands as a weak tropical storm in 48 hours. Thereafter, a track north of the latitude of Kingston, Jamaica, is not to be expected.

Notably, the 0600Z GFS ensembles have shifted hundreds of miles farther southwest relative to 0600Z runs posted yesterday.

[Weatherfreak000]

Circulation (weak) is becoming easier to see as some of the convection near it diminished in the past hour. Could well be a TD tomorrow afternoon and weak TS by Friday morning. Don't see anything to drive it north of the Caribbean toward FL or the East U.S. Coast. Could well track west into Nicaragua/Honduras or Belize if it survives that long. Too early to determine if it will be a threat to the northern Gulf.

That's what I was thinking....perhaps the two best scenarios are gradual dissipation traveling through the Caribbean or a general track towards the GOM staying weak. I don't see what other members see concerning this NW track....

[floridasun78]

I'm still not seeing much of a surface circulation - not as much as yesterday or the day before. That band to the north is more of an outflow boundary than an inflow feature. And there's a linear band of convection stretching westward along 11N. It remains very poorly organized this morning. Still has a fair potential to become a TD in 24-36 hours, and possibly a weak TS (35-40 kts) prior to reaching the eastern Caribbean.

yougot feeling % will go from 60% to 40% at 2pm?

[cycloneye]

12z GFS trending stronger in Western Caribbean.

[ROCK]

Circulation (weak) is becoming easier to see as some of the convection near it diminished in the past hour. Could well be a TD tomorrow afternoon and weak TS by Friday morning. Don't see anything to drive it north of the Caribbean toward FL or the East U.S. Coast. Could well track west into Nicaragua/Honduras or Belize if it survives that long. Too early to determine if it will be a threat to the northern Gulf.

That's what I was thinking....perhaps the two best scenarios are gradual dissipation traveling through the Caribbean or a general track towards the GOM staying weak. I don't see what other members see concerning this NW track....

the LLC did do alittle WNW jog in the latest sat images but I think that was more due to a detachment from the ITCZ....

[Blown Away]

12z GFS still running, but looks like a significant north shift on this run.

[Fego]

Kind of exposed, IMO.



Uploaded with ImageShack.us

[tolakram]

Live loop: http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... mframes=10

We sure that's an LLC, looks rather odd to my eyes, not a lot of low level inflow bands.

Latest

[cycloneye]

Dang! dont look now.

[tolakram]

Conditions, right now, appear to be a little more favorable in front of the system.

[ROCK]

wheres the shear.....

[ROCK]

Live loop: http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... mframes=10

We sure that's an LLC, looks rather odd to my eyes, not a lot of low level inflow bands.

Latest
http://img20.imageshack.us/img20/784/zztemp.jpg

thats it...might not be totally at the surface but very very close....

[ROCK]

at 252hr still in la la land....I wonder why it didnt weaken it this time. I bet after this run the GFDL, HWRF will be running at all times now.

[JonathanBelles]

Quick update on 99L this afternoon. Full update tonight.

http://jonathanbelles.wordpress.com/201 ... on-update/