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Tropical Depression Ernesto - 35 mph - 1004 mb - W 14 mph


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The latest MW is telling. Ernesto's not very consolidated, and the inner core is not really established. So long as this is the case, Ernesto will have a hard time doing RI. For now at least, intensification will probably be slow and staircased. Furthermore, its large circulation might be drawing in some dry air from the mountains of central America.

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Wow your not kidding. Didnt realize that much dry air intrenched him.

The latest MW is telling. Ernesto's not very consolidated, and the inner core is not really established. So long as this is the case, Ernesto will have a hard time doing RI. For now at least, intensification will probably be slow and staircased. Furthermore, its large circulation might be drawing in some dry air from the mountains of central America.

I feel like I've said this all day today, but the dry air that was plaguing the storm the past few days is no longer there. The decrease in convection this afternoon was a diurnal cycle that happens with nearly all weak to moderate TCs. You guys are being far too impatient. Yes the overall circulation envelope has gotten larger after the inner core relaxed from earlier today. However there is still plenty of time for this system to organize over the next 24 hours under high oceanic heat content and very favorable upper level conditions.

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I'm having a bit of trouble interpreting the IR trends. I'm seeing big, sweeping arcs of convective energy-- but gyrating around what appears to be a very large center-- which is strange given the extremely tight core this morning. Or perhaps I'm misinterpreting the imagery...

I believe I see the center around 16.5N 81.7W.

The center has become more broad per microwave imagery. However, thats not a bad thing. A larger circulation will actually be more susceptible to the weakness that will be developing in the Gulf of Mexico, which could pull the storm further northward.

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. As far as I know, there isn't any research indicating that RI is more likely to begin at a certain time of day.

There was a paper from the late 1990s (RI and Lightning?) that was pretty specific about the times that RI began. I have it somewhere. I think it was 2-3AM.

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I feel like I've said this all day today, but the dry air that was plaguing the storm the past few days is no longer there. The decrease in convection this afternoon was a diurnal cycle that happens with nearly all weak to moderate TCs. You guys are being far too impatient. Yes the overall circulation envelope has gotten larger after the inner core relaxed from earlier today. However there is still plenty of time for this system to organize over the next 24 hours under high oceanic heat content and very favorable upper level conditions.

Yes, I understand the diurnal cycles, but I can't but help imagine that downsloping flow off the terrain of ctrl America would have some influence. Or maybe downdrafts from neighboring thunderstorms. Anyway, I'm basing my post mostly off of the microwave data, not IR. Additionally, the diurnal minimum doesn't explain why convection on the eastern periphery of Ernesto has remained steady-state, while the convection near and to the west of the core has dwindled.

Does OHC actually affect the intensification rate of fledgling TC's? And I understand the favorable UL conditions, just need to see this consolidate.

I am curious to see what the recon plane finds.

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I feel like I've said this all day today, but the dry air that was plaguing the storm the past few days is no longer there. The decrease in convection this afternoon was a diurnal cycle that happens with nearly all weak to moderate TCs. You guys are being far too impatient. Yes the overall circulation envelope has gotten larger after the inner core relaxed from earlier today. However there is still plenty of time for this system to organize over the next 24 hours under high oceanic heat content and very favorable upper level conditions.

284395.gif

Convection has not decreased today , only moved to a bad spot east of the center. It has failed wrap up multiple times

The Yucatan micht help it but I am pretty pessimistic with this structure. It kind of has the appearence of an occluded frontal system. Once center becomes enlarged it is hard to shrink it back.

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Yes, I understand the diurnal cycles, but I can't but help imagine that downsloping flow off the terrain of ctrl America would have some influence. Or maybe downdrafts from neighboring thunderstorms. Anyway, I'm basing my post mostly off of the microwave data, not IR. Additionally, the diurnal minimum doesn't explain why convection on the eastern periphery of Ernesto has remained steady-state, while the convection near and to the west of the core has dwindled.

Does OHC actually affect the intensification rate of fledgling TC's? And I understand the favorable UL conditions, just need to see this consolidate.

I am curious to see what the recon plane finds.

Actually, according to some of Jason Dunion's work, it does. The convection in the outer regions tend to pulse up when the inner core pulses down, and vice versa.

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An occluded frontal system? What on earth can you possibly mean? Do occluded frontal systems have symmetric outflow in all quads?

I'm not saying it looks amazing, but c'mon. Let's make sense.

Yeah, strongly agree with this, that makes little sense.

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An occluded frontal system? What on earth can you possibly mean? Do occluded frontal systems have symmetric outflow in all quads?

I'm not saying it looks amazing, but c'mon. Let's make sense.

The east side of the storm does look a little like it has a CF and a WF. I understand those are just rain bands at a 90 degree angle to eachother. This structure might sort itself out if the storm was moving east.

wv0-lalo.jpg

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The east side of the storm does look a little like it has a CF and a WF. I understand those are just rain bands at a 90 degree angle to eachother. This structure might sort itself out if the storm was moving east.

Yeah, but step back and look at the wider view. The system is a tropical, fairly-symmetric gyre. It's just that the center is kind of hollow.

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Yeah, but step back and look at the wider view. The system is a tropical, fairly-symmetric gyre. It's just that the center is kind of hollow.

Hollow cores are your favorite?

Hopefully the next one will be a tighty.

Edit:

And relax I wasn't arguing the system was frontal. Just made a pointless observation that it had some frontal look.

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Very tight core looking at the pressure falls... Bottomed out at 994.5mb extrapolated.

Edit: 6 mb drop over 12.5 miles or 0.5 mb per mile.

Also note from beginning of the single HDOB to that lowest pressure, 3ºC temp rise with the plane holding steady altitude plus/minus 50 meters.

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Pretty soon if not already it's as much a time issue as anything. Regardless of flareups near the center that's not a healthy looking storm. If it magically sheds the outer bands and the micro-core explodes or something then ok. I'd take the under.

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Serious question about diurnal max/mins/RI.

Are inland nocturnal core rain events in warm core systems related to the diurnal max in convection with an offshore cyclone? Beyond the obvious fact that they are both diurnal.

That's a good question. Are you referring to an MCV? Those are fed by the low-level jet, which has a max around 2 AM. The low level jet is basically a substitute energy source instead of ocean-surface latent heat exchange. The ocean is different because the energy source is available 24/7 instead of just at night. In TCs, the nocturnal peak is specifically caused by the solar cycle (more IR cooling in the upper atmosphere at night). In MCVs, the nocturnal peak is caused by the combination of the low-level jet and the solar cycle.

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That's a good question. Are you referring to an MCV? Those are fed by the low-level jet, which has a max around 2 AM. The low level jet is basically a substitute energy source instead of ocean-surface latent heat exchange. The ocean is different because the energy source is available 24/7 instead of just at night. In TCs, the nocturnal peak is specifically caused by the solar cycle (more IR cooling in the upper atmosphere at night). In MCVs, the nocturnal peak is caused by the combination of the low-level jet and the solar cycle.

Hadn't though of MCVs in particular, usually an inland TC. Loses the outer bands at night, and has more intense rain near the center.

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Serious question about diurnal max/mins/RI.

Are inland nocturnal core rain events in warm core systems related to the diurnal max in convection with an offshore cyclone? Beyond the obvious fact that they are both diurnal.

The tropical diurnal maximum is at night because of the nature of the heat source (ocean heat flux). What happens at night is the cloud tops (those very high up / 50+ thousand feet) radiatvely cool to space (no heating from the high altitude sun during daytime).

The result is cooler cloud tops, and a higher heat difference between the sea surface and "top" of the storm. The result is higher m/u CAPE during the night as the heat source is from 'below'. Believe it or not ... Jupiters violent storms are based on this same principle (heat from within the planet rather than sunlight).

Basically it's the cooler cloud tops (radiational cooling) and the warm underlying ocean that cause tropical storms to intensify more at night ... Given the storm has a well developed structure.

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