East Pacific Hurricane Season 2013

[TropicalAnalystwx13]

BULLETIN
TROPICAL DEPRESSION FIVE-E INTERMEDIATE ADVISORY NUMBER 2A
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052013
500 PM PDT THU JUL 04 2013

...DEPRESSION LIKELY TO BECOME A TROPICAL STORM TONIGHT...


SUMMARY OF 500 PM PDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...14.6N 99.6W
ABOUT 160 MI...260 KM S OF ACAPULCO MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* ACAPULCO TO LA FORTUNA

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

[Supercane]

I'm reading the latest discussion on Dalila and I had a question.

 

 

Why does Avila want to "lower the winds gradually?"  I understand that estimating wind speed isn't necessarily easy and/or particularly accurate without a recon mission or something, but he seems to be saying "I think it's a 40/45-knot storm and I'm calling it 50 knots."

 

It's a fairly irrelevant storm, it's not an important difference anyway, and I'm certainly not trying to attack the NHC but as an amateur I'd like to understand the logic of the pros, especially if there's a scientific reason.  Is it simply not feasible to expect a storm to spin down that fast in open water?

 

Avila is probably still haunted by Hurricane Epsilon.

[HurricaneJosh]

Tropical Storm ERICK is threatening Michoacan and Colima. Time to update that thread subtitle-- it's stale.

[icebreaker5221]

Erick is probably past-peak with cloud tops warming steadliy since early last night.  NHC still had Erick as a 70 kt system as of 0900 Z, but I bet we see them lower it by at least 10 kt (maybe more) in the next advisory.  NHC mentions cooler SSTs but it looks like some dry air is wrapping in from the north off mainland MX. 

 

Even with weakening, Erick may still cause TS conditions to the Baja peninsula, especially if it stays right of most guidance. 

[icebreaker5221]

Guidance in good agreement that we should see something starting to develop as early as late this weekend.  Interestingly, genesis should be preceded by a respectable push of cross-equatorial flow from the south.  It's unlikely that this is an actual source of genesis.  If anything, ertel PV conservation tells us that as +PV moves north from the equator, zeta should decrease as f increases (PV = -g(zeta+f)*d(theta)/dP). 

 

However, horizontal convergence of relative vorticity (d(PV/dz) ~ -rho*(del * Vh)) as well as PV production at the level of maximum latent heating (D(PV)/DT~(f+zeta)/rho * d(d(theta)/dt)/dz ) should more than compensate.

 

(Some fun with various simplified forms of the PV equation in an otherwise dead thread). 

 

[Mike.Ventrice]

There's a 2.5 standard deviation CCKW pushing across the Pacific over the next few days... I'm expecting some East Pac mischief to get going! It's actually overpowering the local suppression forced by the MJO. Here's one of those times where you can get a TC tc to spin up in an unfavorable MJO phase.

 

Quote

[icebreaker5221]

There's a 2.5 standard deviation CCKW pushing across the Pacific over the next few days... I'm expecting some East Pac mischief to get going! It's actually overpowering the local suppression forced by the MJO. Here's one of those times where you can get a TC tc to spin up in an unfavorable MJO phase.

 

Quote

 

 

I thought those statistics were only significant for RMM 1 or 2 > 1 sigma (preferably > 2 sigma)?  If so, that would suggest that it's not an "unfavorable MJO", but rather "not a favorable" MJO.  I would suspect a 2 sigma MJO in an unfavorable phase might prevent genesis even in the presence of a Kelvin wave. 

[Mike.Ventrice]

I thought those statistics were only significant for RMM 1 or 2 > 1 sigma (preferably > 2 sigma)?  If so, that would suggest that it's not an "unfavorable MJO", but rather "not a favorable" MJO.  I would suspect a 2 sigma MJO in an unfavorable phase might prevent genesis even in the presence of a Kelvin wave. 

 

While the stats are in support of a favorable superposition with an active MJO, tc-genesis can happen in any RMM phase and these times can occur when a strong CCKW is passing the particular basin. If you look at the time-lon plot I showed above, it shows a good deal of positive VP200 anomalies, representing upp. level convergence. But with the Kelvin wave, you can see a change to negative VP200 anomalies, providing a small window for favorable conditions.

[icebreaker5221]

While the stats are in support of a favorable superposition with an active MJO, tc-genesis can happen in any RMM phase and these times can occur when a strong CCKW is passing the particular basin. If you look at the time-lon plot I showed above, it shows a good deal of positive VP200 anomalies, representing upp. level convergence. But with the Kelvin wave, you can see a change to negative VP200 anomalies, providing a small window for favorable conditions.

 

Right.  I was just noting that I agree that a CCKW can and in this case likely will produce conditions more favorable for genesis, but since the MJO is so weak right now it's more with respect to a neutral environment than with respect to an 'unfavorable' environment.  Since the MJO is within the wheel of death, I'm not sure we can attribute those large-scale positive VP200 anomalies to the MJO. 

[Srain]

The monsoonal trough is getting its act together. The 12Z NCEP Ensembles suggest off the Guatemala to Gulf of Tehuantepec area's of interest.

[Mike.Ventrice]

Right.  I was just noting that I agree that a CCKW can and in this case likely will produce conditions more favorable for genesis, but since the MJO is so weak right now it's more with respect to a neutral environment than with respect to an 'unfavorable' environment.  Since the MJO is within the wheel of death, I'm not sure we can attribute those large-scale positive VP200 anomalies to the MJO. 

 

Some new research I have done shows that the RMM index tends to struggle with the MJO signal during summer time. In fact, there are numerous times where the index struggles in general. Even though the signal runs into the inner core does not necessarily mean there is no MJO signal. It just means that something is projecting onto the leading two principle components that damps the MJO signal out. It appears the strong CCKW pushing across the East Pacific today, later over the Atlantic is causing a conflicting signal with the MJO that is currently over the Maritime Continent. This causes the index to try to focus on both convective signals in both hemispheres, resulting in a decay of the RMM signal. In my opinion, what will happen next is the index will continue show a "weak MJO" (which I don't buy) right up until the CCKW moves back over the central-eastern Pacific (give it about two weeks). Then, we will likely see the RMM turn back on over the central-East Pacific (phases 7-8), right in time for our uptick in Atlantic tc-activity mid August  as the MJO pushes back over the Western Hemisphere

[icebreaker5221]

Some new research I have done shows that the RMM index tends to struggle with the MJO signal during summer time. In fact, there are numerous times where the index struggles in general. Even though the signal runs into the inner core does not necessarily mean there is no MJO signal. It just means that something is projecting onto the leading two principle components that damps the MJO signal out. It appears the strong CCKW pushing across the East Pacific today, later over the Atlantic is causing a conflicting signal with the MJO that is currently over the Maritime Continent. This causes the index to try to focus on both convective signals in both hemispheres, resulting in a decay of the RMM signal. In my opinion, what will happen next is the index will continue show a "weak MJO" (which I don't buy) right up until the CCKW moves back over the central-eastern Pacific (give it about two weeks). Then, we will likely see the RMM turn back on over the central-East Pacific (phases 7-8), right in time for our uptick in Atlantic tc-activity mid August  as the MJO pushes back over the Western Hemisphere

 

 

I totally agree that the index is not perfect.  I've seen a few talks recently where the different contributors to the RMM index don't line up, especially the OLR data.  Still, I think we can both agree that the MJO is pretty weak right now, and there are other factors that contribute to VP200 than just MJO and Kelvin waves.  My point was that you can still have net UL convergence / an unfavorable background environment without the MJO being much of a factor.

 

By the way I wasn't try to give you a hard time, just trying to play devil's advocate. 

[Ed Lizard]

As a hobbyist, an amateur, I have always found the OLR maps more intuitively useful than the phase maps.  I don't understand the difference in filtering in some of the maps used to show CCKWs/MJO, of course.

 

BTW, the signals, whether MJO or Kelvin or neither/both, they are more amplified near and past the Dateline, aren't they.  BTW, wrong basin, but there appears to be a weak signal currently that says the GFS MDR strong wave or TD in a week isn't completely out of the question. 

 

 

[icebreaker5221]

As a hobbyist, an amateur, I have always found the OLR maps more intuitively useful than the phase maps.  I don't understand the difference in filtering in some of the maps used to show CCKWs/MJO, of course.

 

BTW, the signals, whether MJO or Kelvin or neither/both, they are more amplified near and past the Dateline, aren't they.  BTW, wrong basin, but there appears to be a weak signal currently that says the GFS MDR strong wave or TD in a week isn't completely out of the question. 

 

 

You're going to have to be more specific Ed.  Does "near and past" the dateline mean east or west of the dateline? 

 

Assuming you mean east of the dateline since this is the E. Pac thread, there are positive OLR anomalies.  More OLR means less cloud cover / less convection, so convection is currently below average in the E. Pac. 

[Ed Lizard]

You're going to have to be more specific Ed.  Does "near and past" the dateline mean east or west of the dateline? 

 

Assuming you mean east of the dateline since this is the E. Pac thread, there are positive OLR anomalies.  More OLR means less cloud cover / less convection, so convection is currently below average in the E. Pac. 

 

 

Wrong thread again, but I meant Central and Western Pac has the most easily identified OLR signals.  At least on that hotlink.  East Pac and Atlantic are rarely greater  (absolute value) than +/- 20  Of course, as a hobbyist, I don't even really know what that scale means, except above or below normal outgoing long wave radiation, or "lots of clouds, not many clouds".

[Mike.Ventrice]

I totally agree that the index is not perfect.  I've seen a few talks recently where the different contributors to the RMM index don't line up, especially the OLR data.  Still, I think we can both agree that the MJO is pretty weak right now, and there are other factors that contribute to VP200 than just MJO and Kelvin waves.  My point was that you can still have net UL convergence / an unfavorable background environment without the MJO being much of a factor.

 

By the way I wasn't try to give you a hard time, just trying to play devil's advocate. 

 

Ah yes I understand.. it's a good thing and provides a basis for discussion That being said, have you ever seen a wavenumber frequency spectrum of VP200? The main signals are MJO/Kelvin waves (WITH NO GAP), and these fast westward propagating Rossby waves that are barotropic in nature (I forgot what they are called, Matt Wheeler told me once but I can't remember it).

 

[Mike.Ventrice]

Oh and the MJO is still at an amplitude > 1 sigma.. The RMM index is currently failing as there are two main cores of convection. One that is the MJO over the eastern hem and one is the strong CCKW over S. America. The sum of the two = weak MJO signal.

 

[Srain]

A new Lemon SSW of Acapulco has been tagged 98E. SHIPS takes it to a 'cane generally heading WNW.

[Ed Lizard]

6Z GFS takes it in general direction of Hawai'i, but I suspect it doesn't get to the 50th state.

 

[Yellow Evan]

Hello, I am a new poster and longtime EPAC fan.

 

Anyhow, I have been diying for an EPAC major, and I think 98E has a small chance at becoming one. However, I don't think it will happen. IMO it will be like Barbara Cosme, Dallia, and Erick and peak as Category 1's. At least this storm won't threaten land unlike the last four storms, so you can root for it to RI.

 

FTR, the GFS does show a parade of storms in the long run, but I dobut it will happen, so the GFS thinks MJO will unreasitcally reutrn to the EPAC. Boy, the GFS has been acting strnage lately

[phil882]

Hello, I am a new poster and longtime EPAC fan.

 

Anyhow, I have been diying for an EPAC major, and I think 98E has a small chance at becoming one. However, I don't think it will happen. IMO it will be like Barbara Cosme, Dallia, and Erick and peak as Category 1's. At least this storm won't threaten land unlike the last four storms, so you can root for it to RI.

 

FTR, the GFS does show a parade of storms in the long run, but I dobut it will happen, so the GFS thinks MJO will unreasitcally reutrn to the EPAC. Boy, the GFS has been acting strnage lately

 

Welcome aboard!

 

I generally agree with your assessment, probably another low end hurricane in the EPAC. While it hardly matters, I think the NHC is being a tad conservative with its 20% 48 hour forecast for 98E. I see already an established broad llc becoming better defined as convection is starting to take a banded appearance in the southern semicircle. Both the GFS and ECMWF are indicating development in the short/medium range, and unlike in the Atlantic basin, they tend to be too slow with TCG events in the EPAC. I also like the amount of southerly inflow on visible which should supply ample moisture from the ITCZ for this disturbance as it moves towards the Central Pacific. Finally, over the last few days, there was a passage of a CCKW over the EPAC, and typically its shortly after the passage that you see an increased probability of TCG (in the Atlantic basin, I'm not sure if Mike has found a similar correlation in the EPAC).

 

. 

[icebreaker5221]

98E still having some trouble getting its act together.  The deepest convection continues from 13-15 N, while a residual region of mid-level rotation associated with an embedded MCV last night is much further south - around 10 N.  The surface circulation is likely somewhere in-between. 

 

Until the surface and mid-level circulation centers can become vertically aligned and co-located with the strongest convection, we won't have genesis.  Models suggest this one may need another 24 h, perhaps more. 

 

[HurricaneJosh]

We're deep into the EPAC summer fish season now.  Should get interesting again late Sep and Oct as stuff starts recurving back toward the coast.

[Yellow Evan]

We're deep into the EPAC summer fish season now.  Should get interesting again late Sep and Oct as stuff starts recurving back toward the coast.

 

Well, 4 of the first 5 storms's of 2013 PHS affected land. And fish season is not boring, you get to root for RI without ppl getting killed

[HurricaneJosh]

Well, 4 of the first 5 storms's of 2013 PHS affected land. And fish season is not boring, you get to root for RI without ppl getting killed

 

Fish season = this middle part of the season.  It's not that uncommon to have early-season landfalls like we've seen.

 

RI out in the open ocean is kinda whatevz for me.

[Yellow Evan]

Fish season = this middle part of the season.  It's not that uncommon to have early-season landfalls like we've seen.

 

RI out in the open ocean is kinda whatevz for me.

 

Well, 4 out of the first 5 storms doing damage is slightly unusal. I know that fish season is the middle of the season (from July 10 to August 25 in my eyes). Anyhow, 98E looks a bit lost tonight. Has 2-3 days left to form though.

[Yellow Evan]

98E is at 80% if anyone cares.

[icebreaker5221]

Total fish, although NHC has Flossie possibly affecting Hawaii as a weakening TD by Tues. There's a slight chance this thing could become a hurricane within the next 36 h, although Cat 1 is probably the upper bounds. Flossie will move over sub 25 C and even sub 24 C waters thereafter.

[attachment=102298:143754W5_NL_sm.gif]

TROPICAL STORM FLOSSIE DISCUSSION NUMBER 3

NWS NATIONAL HURRICANE CENTER MIAMI FL EP062013

800 AM PDT THU JUL 25 2013

SINCE THE BIG BURST OF CONVECTION ABOUT 12 HOURS AGO...THE STRUCTURE

OF THE CYCLONE HAS CHANGED LITTLE IN ORGANIZATION. IN FACT...

T-NUMBERS FROM BOTH TAFB AND SAB ARE STILL 2.5 ON THE DVORAK SCALE.

THE INITIAL INTENSITY IS KEPT AT 35 KNOTS IN THIS ADVISORY...BUT

FLOSSIE STILL HAS THE OPPORTUNITY TO STRENGTHEN SOME BEFORE THE

CYCLONE MOVES OVER COOLER WATERS IN ABOUT 36 TO 48 HOURS. THE

EFFECTS OF COOLER WATERS AND ADVERSE SHEAR MOST LIKELY WILL RESULT

IN WEAKENING THEREAFTER...AND FLOSSIE IS FORECAST TO BE A TROPICAL

DEPRESSION BY THE END OF THE FORECAST PERIOD...IF NOT SOONER.

MICROWAVE DATA AROUND 1200 UTC INDICATE THAT THE CENTER WAS A LITTLE

BIT SOUTH OF PREVIOUSLY ESTIMATED. THE BEST ESTIMATE OF THE OVERALL

MOTION IS 275 DEGREES AT ABOUT 14 KNOTS. FLOSSIE IS FULLY EMBEDDED

WITHIN A DEEP LAYER OF EASTERLY WINDS SOUTH OF THE EASTERN PACIFIC

SUBTROPICAL RIDGE. GLOBAL MODELS INDICATE THAT THIS STEERING

PATTERN SHOULD PERSIST FOR THE NEXT SEVERAL DAYS...KEEPING FLOSSIE

ON A GENERAL WEST TO WEST-NORTHWESTWARD TRACK WITH NO SIGNIFICANT

CHANGE IN FORWARD SPEED. BY THE END OF THE FORECAST PERIOD...A

WEAKER FLOSSIE IS EXPECTED TO BE STEERED WESTWARD BY THE LOW-LEVEL

TRADE WINDS. THE OFFICIAL FORECAST IS VERY CLOSE TO THE

MULTI-MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INIT 25/1500Z 15.3N 125.6W 35 KT 40 MPH

12H 26/0000Z 15.5N 128.0W 45 KT 50 MPH

24H 26/1200Z 16.2N 131.1W 50 KT 60 MPH

36H 27/0000Z 17.0N 134.0W 50 KT 60 MPH

48H 27/1200Z 17.8N 137.0W 45 KT 50 MPH

72H 28/1200Z 19.0N 143.0W 40 KT 45 MPH

96H 29/1200Z 20.0N 148.0W 35 KT 40 MPH

120H 30/1200Z 20.5N 154.0W 30 KT 35 MPH

$$

FORECASTER AVILA

[Ed Lizard]

Well, now that Dorian is crashing and burning.

 

 

[TropicalAnalystwx13]

5pm EDT -