EPAC Tropical Action 2011

[am19psu]

Because his father, the GFS is hauling ass... around 1.5 days faster than the Euro. The GFS EnKF and CMC support the Euro... the Ukie is faster than the Euro, but a little slower than the GFS

I think they will trend slower ... but there's always the possibility that the GFS might perform a coup.

Yep.

I know, I know, we'll get a room.

[HurricaneJosh]

The new advisory brings Jova ashore as a major, with winds of 100 kt. Wow.

[Scott747]

The new advisory brings Jova ashore as a major, with winds of 100 kt. Wow.

I advised my lone client of this news a few hours ago.

[HurricaneJosh]

I advised my lone client of this news a few hours ago.

Your lone client was pleased as punch to hear from ya.

[hm8]

So if Jova and Irwin both become majors, which is definitely feasible, the EPAC would be at 10/8/6. Which is kinda redic.

[klw]

The new advisory brings Jova ashore as a major, with winds of 100 kt. Wow.

From the discussion

http://www.wunderground.com/tropical/ep201110.disc.html

The intensity guidance is higher than in theprevious cycle...and the official wind speed forecast is raisedfrom the previous one. This is between the intensity modelconsensus and the GFDL/HWRF models. This forecast could be stillon the conservative side since the GFDL/HWRF make Jova a categoryfour hurricane in a few days.

Have a fun chase, be safe.

[CUmet]

The model trend of weakening Jova right before landfall continues. That is the most troubling aspect of this forecast for me. I still brought it ashore as a Cat 2/3 this morning, and I feel confident it will be there within 100 mi of the coast, but the RW shown in the models lowers my confidence at landfall.

It seems the operational and EnKF GFS are the main ones doing this. The ECMWF keeps this very strong right up until landfall. I'm rather puzzled by this given the favorable upper level environment and rising SST/OHC right up until the coast.

[phil882]

The model trend of weakening Jova right before landfall continues. That is the most troubling aspect of this forecast for me. I still brought it ashore as a Cat 2/3 this morning, and I feel confident it will be there within 100 mi of the coast, but the RW shown in the models lowers my confidence at landfall.

I'm going to take a stab and say that a lot of the topographic influences that cause weakening in the Atlantic basin in the Bay of Campeche, are also present in this basin leading to landfall along the mainland Mexican Coastline. Thus, it would be preferable to have a rapidly moving TC before landfall rather than a system that is meandering. I think the reason why the ECWMF weakens the system so much is because of its slow forward motion near landfall and allowing the terrain to have a detrimental affect on the cyclone.

[wxmx]

I'm going to take a stab and say that a lot of the topographic influences that cause weakening in the Atlantic basin in the Bay of Campeche, are also present in this basin leading to landfall along the mainland Mexican Coastline. Thus, it would be preferable to have a rapidly moving TC before landfall rather than a system that is meandering. I think the reason why the ECWMF weakens the system so much is because of its slow forward motion near landfall and allowing the terrain to have a detrimental affect on the cyclone.

But the 0z Euro doesn't weaken it... it's 952mb just prior to landfall in the 0z run.... steadily strengthening up to landfall.

[wxmx]

But the 0z Euro doesn't weaken it... it's 952mb just prior to landfall in the 0z run.... steadily strengthening up to landfall.

12Z on the other hand :S ... from 944 to 984 at landfall

[HurricaneJosh]

Jova is slowly strengthening, despite shear. It's now up to 55 kt, as of 2 pm PDT.

And the new forecast is hawt. It now shows the cyclone approaching the coast with winds of 105 kt on Monday. The forecast track has shifted a tad S, with the center now crossing closer to ZLO.

[wxmx]

Damn...that was Irwin

[CUmet]

I'm going to take a stab and say that a lot of the topographic influences that cause weakening in the Atlantic basin in the Bay of Campeche, are also present in this basin leading to landfall along the mainland Mexican Coastline. Thus, it would be preferable to have a rapidly moving TC before landfall rather than a system that is meandering. I think the reason why the ECWMF weakens the system so much is because of its slow forward motion near landfall and allowing the terrain to have a detrimental affect on the cyclone.

One difference though is that the shape of the coastline south of Puerto Vallarta is convex as opposed to the concave Bay of Campeche. Not sure how much of an impact that has.

[wxmx]

One difference though is that the shape of the coastline south of Puerto Vallarta is convex as opposed to the concave Bay of Campeche. Not sure how much of an impact that has.

For a decent moving system (>10-12 kts), I would think land disruption would be minimal.

[HurricaneJosh]

One difference though is that the shape of the coastline south of Puerto Vallarta is convex as opposed to the concave Bay of Campeche. Not sure how much of an impact that has.

Howdy! What are your thoughts Re: Jova's intensity leading up to landfall? Wxmx and I are planning to chose this one, and yet we're a tad spooked Re: the harsh, pre-landfall unraveling depicted in the 12Z Euro and GFS. (Despite this, the NHC was quite bullish in the 2 pm PDT package.)

Thoughts?

[HurricaneJosh]

For a decent moving system (>10-12 kts), I would think land disruption would be minimal.

Yep. When Karl crapped out last year, it approached the coast quite slowly. I think that hurt it.

[CUmet]

Howdy! What are your thoughts Re: Jova's intensity leading up to landfall? Wxmx and I are planning to chose this one, and yet we're a tad spooked Re: the harsh, pre-landfall unraveling depicted in the 12Z Euro and GFS. (Despite this, the NHC was quite bullish in the 2 pm PDT package.)

Thoughts?

I don't think this will completely unravel as it makes landfall. Some weakening on the order of what Karl did last year is possible, but that's probably about the worst of possibilities. Prior to the last couple hours before landfall, this should be strengthening at a decent rate, perhaps rapid, as the oceanic and atmospheric conditions are quite favorable. My best guess at landfall is right around where the NHC has it right now, somewhere in the 90-110 kt range.

[HurricaneJosh]

I don't think this will completely unravel as it makes landfall. Some weakening on the order of what Karl did last year is possible, but that's probably about the worst of possibilities. Prior to the last couple hours before landfall, this should be strengthening at a decent rate, perhaps rapid, as the oceanic and atmospheric conditions are quite favorable. My best guess at landfall is right around where the NHC has it right now, somewhere in the 90-110 kt range.

OK, cool. So you think essentially strengthening up to landfall, with perhaps some deterioration in the final hours due to inflow off the land? Am I understanding correctly?

[CUmet]

OK, cool. So you think essentially strengthening up to landfall, with perhaps some deterioration in the final hours due to inflow off the land? Am I understanding correctly?

Something like that, with emphasis on perhaps.

[HurricaneJosh]

Something like that, with emphasis on perhaps.

Cool, thanks. And don't worry-- I don't take any speculation here as a guarantee. I wish we had that ability to see into the future!

[HurricaneJosh]

The 8 pm PDT advisory has Jova steady at 55 kt. It's still experiencing shear.

This having been said, the NHC is still predicting the shear to abate, and for Jova to be a Cat 3 (105 kt) when it reaches the MX coast just NW of Manzanillo Monday evening.

[HurricaneJosh]

The 2 am PDT advisory has Jova in a steady state at 55 kt, but the convection is covering the center now and the system looks way more symmetric-- so this could be the start of an intensification burst. The models are now suggesting an annoying left hook late in the forecast period, as the cyclone nears the coast. Overall it looks complicated. Oh, and they've dialed back the intensity forecast a bit-- now down to 95 kt.

In other news... Irwin is steady state. And there's a new Mandarin (99E) SSW of the Gulf of Tehuantepec.

Just a packed weather map on this side.

[Ed Lizard]

Berg's discussion both systems, re SHIPS and warm upper temperatures. Jova is still cranking out tops in excess (that may be poorly worded) of -80ºC, I'd think convection that deep would be a sign it isn't that stable out there.

Anyone have a CI plot, actual versus climatological like someone posts for the Caribbean?

[OHweather]

Irwin's low level center appears to be exposed on conventional and microwave satellite imagery:

The university of Wisconsin CIMSS page is analyzing only 10-20 knots of shear over the system, with the strongest upper level winds appearing to be to the north of the hurricane:

Both the 0z GFS and Euro appear to show similar (if not slightly improving) upper level winds through 0z Sunday, so perhaps Irwin's low level center will be able to slip back under the convection through the day today:

A close examination of the 250-500mb wind fields does not suggest a layer of shear below the 200mb level, that would not be picked up by the traditional 850mb-200mb shear analysis products, however the 0z ECM does keep Irwin's low level and upper level centers slightly disjointed today:

(0z ECM 300mb winds over Irwin, valid 0z Sunday):

(0z ECM sfc winds, same viewing window, valid same time as 300mb winds):

Given Irwin's currently exposed state, suggesting easterly shear has tilted the vortex, I believe Irwin has peaked. The 0z GFS/ECM do not show hostile conditions developing immediately over the hurricane, however the ECM continued to show a tilted vortex through the day. I expect a lowered intensity for the 8am PDT advisory, and likely a steady state with some possible small fluctuations in Irwin's strength for the rest of the day.

Jova is essentially under an upper level anti-cyclone, and a low resolution microwave pass from just before 4am PDT suggests that a small inner core is developing, with a small curved band trying to wrap around the center of Jova:

While Jova's outflow is still somewhat limited in the eastern quadrant indicating the cyclone is still fighting some easterly-northeasterly shear, it has improved in almost every quadrant overnight. The ECM QPF fields continue to show a somewhat asymmetric system through tonight, however do show the cyclone remaining under an upper level ridge.

The slowly subsiding shear over warm waters with an improving inner core and outflow lead me to believe either way that Jova will most likely become a hurricane by 2pm PDT today.

[Ed Lizard]

Berg's discussion both systems, re SHIPS and warm upper temperatures. Jova is still cranking out tops in excess (that may be poorly worded) of -80ºC, I'd think convection that deep would be a sign it isn't that stable out there.

Anyone have a CI plot, actual versus climatological like someone posts for the Caribbean?

Stewart seems to address this question...

JOVA IS EXPECTED TO REMAIN IN A MODERATE VERTICAL SHEAR REGIME FOR

ANOTHER 12 HOURS OR SO. AFTER THAT...ENVIRONMENTAL CONDITIONS

APPEAR FAVORABLE FOR STRENGTHENING...POSSIBLY EVEN FOR RAPID

INTENSIFICATION...RIGHT UP UNTIL LANDFALL. THE GFS-BASED SHIPS

GUIDANCE APPEARS TO BE CONTAMINATED BY UPPER-LEVEL WARMING CREATED

IN THE MODEL AS IT STRENGTHENS JOVA. LIKEWISE...THE STRONG VERTICAL

SHEAR SHOWN IN THE MODEL IS LIKELY DUE TO ENHANCED OUTFLOW THAT

DEVELOPS TO THE NORTHEAST OF THE CYCLONE BY 48 HOURS. IT IS WORTH

NOTING THAT BOTH THE HWRF AND GFDL MODELS MAKE JOVA A CATEGORY 4

HURRICANE PRIOR TO LANDFALL. THE OFFICIAL INTENSITY FORECAST IS

SIMILAR TO THE PREVIOUS ADVISORY AND REMAINS WELL ABOVE STATISTICAL

GUIDANCE AND THE INTENSITY CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 15.8N 110.4W 60 KT 70 MPH

12H 09/0000Z 16.0N 109.6W 65 KT 75 MPH

24H 09/1200Z 16.1N 108.6W 70 KT 80 MPH

36H 10/0000Z 16.2N 107.5W 80 KT 90 MPH

48H 10/1200Z 16.5N 106.5W 90 KT 105 MPH

72H 11/1200Z 18.3N 105.3W 95 KT 110 MPH

96H 12/1200Z 21.5N 104.5W 30 KT 35 MPH...INLAND

120H 13/1200Z...DISSIPATED

$$

FORECASTER STEWART

[HurricaneJosh]

Shame on you naughty kitties for not watering the EPAC thread today!

Jova was declared a hurricane this afternoon, and it's looking more symmetric on IR imagery.

Meanwhile, Irwin's been downgraded to TS and there's a cherry SSE of Acapulco. Crazy-full map.

[wxsmwhrms]

99E is kind of interesting to me. Has some decent spin to it tonight, and NHC is now showing it at 90%. EnKF brings it into El Salvador as a decent looking system (1004 mb low) . Not an expert by any means on EPAC climo - how often do systems come in from the west at that low of a latitude?

[HurricaneJosh]

99E is kind of interesting to me. Has some decent spin to it tonight, and NHC is now showing it at 90%. EnKF brings it into El Salvador as a decent looking system (1004 mb low) . Not an expert by any means on EPAC climo - how often do systems come in from the west at that low of a latitude?

I don't know about tropical storms, but there's no known instance of a hurricane making landfall S of MX on that side.

P.S. Where do you think Jova's going? (You can't show yourself here tonight and not expect me to ask. )

[HurricaneJosh]

Irwin's low level center appears to be exposed on conventional and microwave satellite imagery:

The university of Wisconsin CIMSS page is analyzing only 10-20 knots of shear over the system, with the strongest upper level winds appearing to be to the north of the hurricane:

Both the 0z GFS and Euro appear to show similar (if not slightly improving) upper level winds through 0z Sunday, so perhaps Irwin's low level center will be able to slip back under the convection through the day today:

A close examination of the 250-500mb wind fields does not suggest a layer of shear below the 200mb level, that would not be picked up by the traditional 850mb-200mb shear analysis products, however the 0z ECM does keep Irwin's low level and upper level centers slightly disjointed today:

(0z ECM 300mb winds over Irwin, valid 0z Sunday):

(0z ECM sfc winds, same viewing window, valid same time as 300mb winds):

Given Irwin's currently exposed state, suggesting easterly shear has tilted the vortex, I believe Irwin has peaked. The 0z GFS/ECM do not show hostile conditions developing immediately over the hurricane, however the ECM continued to show a tilted vortex through the day. I expect a lowered intensity for the 8am PDT advisory, and likely a steady state with some possible small fluctuations in Irwin's strength for the rest of the day.

Jova is essentially under an upper level anti-cyclone, and a low resolution microwave pass from just before 4am PDT suggests that a small inner core is developing, with a small curved band trying to wrap around the center of Jova:

While Jova's outflow is still somewhat limited in the eastern quadrant indicating the cyclone is still fighting some easterly-northeasterly shear, it has improved in almost every quadrant overnight. The ECM QPF fields continue to show a somewhat asymmetric system through tonight, however do show the cyclone remaining under an upper level ridge.

The slowly subsiding shear over warm waters with an improving inner core and outflow lead me to believe either way that Jova will most likely become a hurricane by 2pm PDT today.

I forgot to thank you for this analysis yesterday. . I enjoyed reading it-- and it looks like you were right about Irwin.

[wxsmwhrms]

I don't know about tropical storms, but there's no known instance of a hurricane making landfall S of MX on that side.

P.S. Where do you think Jova's going? (You can't show yourself here tonight and not expect me to ask. )

I think the analyses already made on here are right on target. I kind of wonder if what is being discussed by NHC about the ensembles is due to the models leaving behind some remnant low behind the main cyclone. The op GFS clearly shows the system moving well inland - but yet still has rather low pressures (1000 mb) remaining offshore in the wake of the system.