E Pacific Tropical Action of 2014

[Windspeed]

That bit of improvement earlier is going to be short-lived as shear appears to be encroaching on the CDO now.

[Yellow Evan]

Let's not be negative. Amanda's holding up well, weakening much slower than most EPAC storms so far. Still 115 knts at 15z.

[phil882]

Let's not be negative. Amanda's holding up well, weakening much slower than most EPAC storms so far. Still 115 knts at 15z.

 

That's because Amanda is still not moving very quickly to the north... vertical wind shear (VWS) ramps up substantially above 15N (Amanda is only at 13.2N). It doesn't look like there has been enough upwelling to substantially hinder the storm, so most of the weakening thus far has been due to a gradual increase in the VWS. 

[Yellow Evan]

Amanda's becoming less organized now. I'd say it is around 105 knts, though you could argue for lower.

[Yellow Evan]

That's because Amanda is still not moving very quickly to the north... vertical wind shear (VWS) ramps up substantially above 15N (Amanda is only at 13.2N). It doesn't look like there has been enough upwelling to substantially hinder the storm, so most of the weakening thus far has been due to a gradual increase in the VWS. 

 

I think dry air is hindering it a bit as well.

[phil882]

I think dry air is hindering it a bit as well.

 

Naturally... as the wind shear increases from the south and southwest, drier mid-level air from those locations will get advected into the inner core. 

[hm8]

[wxtrackercody]

Outside of a tilt between the low and mid-level centers, it would appear that the shear from the upper-level low to Amanda's NW did very little to hurt it. This is probably because the shear vectors were nearly parallel to the storm's movement. Some dry air was entrained into the system earlier, but a big burst of convection got rid of most of it.

 

As of late, the eye has warmed appreciably and eyewall convection has cooled. A 0338z microwave pass showed a very vigorous eyewall despite the aforementioned tilt in centers. Satellite intensity estimates are rising again (latest from CIMSS is 109.8kt). Don't think it's unreasonable to suggest that Amanda has attained major hurricane status again, no matter how brief this strengthening phase may be.

 

Certainly a fun first storm.

 

[HurricaneJosh]

Hurricane-flavored fish!

 

Well, that sure was a quality fish.

[Mike.Ventrice]

Models are hinting of another East Pacific system around Day 9-10 as an easterly wave pushes off South America, setting up what looks to be a Gulf of Tehuantepec gap wind event.  The GFS on the other hand tracks the easterly wave northward and spins up a storm over the Gulf of Mexico. The EC-ensembles gives the East Pacific system a 40% chance, whereas the northern GOM solution a 10% chance. The GFS ensembles gives near equal probabilities for the East Pac verses GOM development area, with slightly higher probabilities for the GOM system..   I'm more in favor of the European solution, as GFS typically struggles with tropical convective disturbances in response to how the model handles convection, especially during the time frame where the model degrades in horizontal resolution. 

 

https://twitter.com/WSI_Energy/status/471204189138604032/photo/1

[Yellow Evan]

Amanda did return to 110 knts. I would not rule out a return to Cat 4.

[phil882]

Models are hinting of another East Pacific system around Day 9-10 as an easterly wave pushes off South America, setting up what looks to be a Gulf of Tehuantepec gap wind event.  The GFS on the other hand tracks the easterly wave northward and spins up a storm over the Gulf of Mexico. The EC-ensembles gives the East Pacific system a 40% chance, whereas the northern GOM solution a 10% chance. The GFS ensembles gives near equal probabilities for the East Pac verses GOM development area, with slightly higher probabilities for the GOM system..   I'm more in favor of the European solution, as GFS typically struggles with tropical convective disturbances in response to how the model handles convection, especially during the time frame where the model degrades in horizontal resolution. 

 

https://twitter.com/WSI_Energy/status/471204189138604032/photo/1

 

We have been talking about this threat a little bit over in the ATL thread... I agree with you for the most part, as I favor the EC solution over the GFS. Both of the models, however, agree that a large gyre-like disturbance developing in the next 5 days with the TC evolving out of the larger disturbance. Whether or not the gyre develops over the Caribbean / Central America / or the EPAC is where the uncertainty is at right now.

[vitaminmawc]

ACE at 16.

[Yellow Evan]

Back to Amanda, ATCF brings it down to 65 knots.

[Mike.Ventrice]

We have been talking about this threat a little bit over in the ATL thread... I agree with you for the most part, as I favor the EC solution over the GFS. Both of the models, however, agree that a large gyre-like disturbance developing in the next 5 days with the TC evolving out of the larger disturbance. Whether or not the gyre develops over the Caribbean / Central America / or the EPAC is where the uncertainty is at right now.

 

Thanks Philippe! I actually saw your thread about this in the other forum after I shot it out.  But yeah makes sense dynamically thanks for sharing your thoughts. The medium-range models have been all over the place with regards to the extra-tropical pattern across the U.S. and no doubt will struggle in the sub-tropics/tropics. After taking a closer look this morning, the storm is clearly there in the GFS prior to the degradation of spatial resolution but I still have a tough time swallowing the evolution to genesis. 

 

It appears the GFS is breaking down a zonally oriented strip of low-level vorticity over the Caribbean on June 1, which then spins up into a mid-tropospheric vortex the following day over the western Caribbean. In addition to the close proximity of land, there's also a good deal of westerly vertical wind shear imposed over the system which may make it difficult for any a low-level vortex to spin up. 

 

http://www.atmos.albany.edu/student/ventrice/real_time/maps/u850/total/atlantic_forecast.html

 

The European operational model shows more of a broad-scale gyre over Central America as you state, with the main area of low-level cyclonic vorticity located over the eastern Pacific, due south of the Gulf of Tehuantepec.  The model never spins up the second area of vorticity over the Caribbean/GOM like the GFS in the region of moderate westerly vertical wind shear. 

 

That  being said, there are some European ensemble members that emerge a vort-max over the Bay of Campeche on June 9 so there is still some support for a GOM system. Get those real-time running diagnostics for your gyre cases going Phil!  Interesting that we are seeing a weak MJO signature emerge over the Indian Ocean, indicative we are in the lower-tropospheric westerly wind phase of the MJO over the Western Hemisphere. 

 

[phil882]

Kinda surprised Amanda kicked back up convective wise this morning... the NHC says theres is poor organization with the convective structure, but I disagree.

 

 

There is obviously still some vertical tilt in the circulation, but this is better organized than it was 24 hours ago. The storm sits on a strong moisture and SST gradient, and so far appears to be avoiding a substantial dry air intrusion. Now that the shear has decreased a bit as well, there might be some life in it yet. The latest GFS suggests Amanda might make it pretty close to the Mexican coastline before the upper-level trough leaves it behind. The models have been known to perform poorly in this region with regards to slow moving TCs before (anyone remember Manuel last year?)

 

 

[Yellow Evan]

Amanda down to 50 knts as of 21z.

[Ground Scouring]

The mid-level circulation is clearly decoupling from the low-level center, which should reduce the likelihood for sustained convection within the next 24 hours as Amanda moves over cooler SSTs, meaning a more stable thermodynamic environment. I think that, while the GFS has handled Amanda well up until now, the weakening over the next day will be much more rapid than that depicted by the model, so I think from this point on the ECMWF solution (more rapid dissipation) will hold.

[phil882]

The mid-level circulation is clearly decoupling from the low-level center, which should reduce the likelihood for sustained convection within the next 24 hours as Amanda moves over cooler SSTs, meaning a more stable thermodynamic environment. I think that, while the GFS has handled Amanda well up until now, the weakening over the next day will be much more rapid than that depicted by the model, so I think from this point on the ECMWF solution (more rapid dissipation) will hold.

 

I'm with you... now that the low and mid-level circulations have decoupled, a ECMWF like solution seems much more likely. 

[Mike.Ventrice]

A nice illustration of what looks to be a series of radially propagating cold downdrafts during the collapse of convection over Amanda yesterday- will need to check an IR/visible loop to confirm though.

 

[Yellow Evan]

New mandarin from that same system. Could be problematic for MX due to its slow motion and large size.

[Yellow Evan]

Which is now a 70/90 cherry.

[wxtrackercody]

Though 93E lacks in convective organization, ASCAT passes over the past 2 days has showed that there is a closed and well-defined circulation center. CIMSS maps show two distinct areas of 850mb vorticity, one with 93E itself and the other with the area of showers and thunderstorms just southwest of the Gulf of Tehuantepec. It'll be interesting to see what happens between these over the next few days, as the GFS strengthens both of them.

 

[phil882]

Though 93E lacks in convective organization, ASCAT passes over the past 2 days has showed that there is a closed and well-defined circulation center. CIMSS maps show two distinct areas of 850mb vorticity, one with 93E itself and the other with the area of showers and thunderstorms just southwest of the Gulf of Tehuantepec. It'll be interesting to see what happens between these over the next few days, as the GFS strengthens both of them.

 

This the hallmark of a gyre circulation. There is closed center of circulation, but both the convective and vorticity profile doesn't indicate much organization. In fact, most of the vorticity is focused in strips on the outer periphery of the circulation. It will take some time for such a circulation to consolidate, especially if convection doesn't organize as quickly as forecasted. What often happens is that a TD/TS does form, but its often the smaller circulation rotating around a much larger circulation. The forthcoming trough interaction with the upper-level disturbance in the Gulf of Mexico will also complicate the picture. The 1200 UTC ECMWF suggests that this same system in approximately the same state of organization will still be located near or over Central America in 7.5 days!

 

This could be an absolute disaster rainfall wise for portion of Mexico and Central America. 

[Yellow Evan]

Really gonna be a big rain maker IMO. Organization-wise, there were no significant changes today. I should expect some improvement tomorrow though.

[wxtrackercody]

Invest 93E looks much better than 12 hours ago, with much more, and much more organized, convection over a well-defined center. Both SAB and TAFB came in at T1.0 earlier; we might see designation this evening if trends continue.

 

[Yellow Evan]

Honestly, I think it's TD-worthy right now.

[wxmeddler]

Invest 94E has spouted -80°C tops for the past 6 hours now and has been cranking since D-Max, now approaching D-Min, it looks like it's not slowing down. I would think that NHC could call it a TD within the next 12 hrs (5PM or 5AM).

[Srain]

Invest 94E has spouted -80°C tops for the past 6 hours now and has been cranking since D-Max, now approaching D-Min, it looks like it's not slowing down. I would think that NHC could call it a TD within the next 12 hrs (5PM or 5AM).

93E is now TD 2E

[wxmeddler]

93E is now TD 2E

 

TROPICAL DEPRESSION TWO-E DISCUSSION NUMBER   1NWS NATIONAL HURRICANE CENTER MIAMI FL       EP022014200 PM PDT MON JUN 02 2014The low pressure area located south of the Gulf of Tehuantepechas acquired enough organized deep convection to be classified as atropical depression.  The initial intensity is set at 25 kt, whichis based Dvorak classifications from TAFB and SAB, and a shipobservation within the eastern portion of the circulation.Environmental conditions, consisting of low vertical wind shear andwarm sea surface temperatures, favor intensification during the nextfew days.  The primary limiting factors are likely to be thelarge and sprawling structure of the cyclone and interactionwith land later in the forecast period.The somewhat uncertain initial motion estimate is 330 degrees at 3kt. The depression is forecast to move slowly northwestward tonorthward between a mid to upper-level ridge over thewest-central Caribbean Sea and a mid- to upper-level troughextending southwestward across the western Gulf of Mexico.  Whilemost of the global models agree on a general northwestward tonorthward motion during the next several days, there are largedifferences in the forward speed of the cyclone, and how soonthe center nears the coast in the model predictions. The GFS shows afaster motion and brings the cyclone to the coast within 2 to 3days.  On the other hand, the ECMWF keeps the depression offshorefor more than 5 days.  The NHC forecast generally lies between thesescenarios and shows a slow motion toward the coast of the Gulfof Tehuantepec.  Due to the high amount of uncertainty on thetiming of the approach to southern Mexico, a tropical storm watchhas been issued for a portion of the coast of southeastern  Mexico.FORECAST POSITIONS AND MAX WINDSINIT  02/2100Z 13.1N  94.1W   25 KT  30 MPH 12H  03/0600Z 13.5N  94.6W   30 KT  35 MPH 24H  03/1800Z 14.0N  95.0W   35 KT  40 MPH 36H  04/0600Z 14.5N  95.1W   40 KT  45 MPH 48H  04/1800Z 15.0N  95.0W   45 KT  50 MPH 72H  05/1800Z 15.3N  95.0W   50 KT  60 MPH 96H  06/1800Z 15.6N  95.0W   50 KT  60 MPH120H  07/1800Z 16.0N  95.0W   45 KT  50 MPH$$Forecaster Brown