The UK met office is more sympathetic to it being warm core than other output but as to whether that is sufficient to classify it being tropical in nature, is beyond the scope of my knowledge.

 


 

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I've tried to find definitions for tropical cyclones and I've really struggled, the problem is the lines are so blurred. I mean even the 2005 Catogary 2 hurricane that hit Brazil was so controversial that Brazil did not acknoledge it as tropical for years (hurricanes don't form in the south atlantic!), NOAA does acknowledge the likes of Hurricane Vince and Tropical storm Grace; both which formed in SSTs of about 20C. But if we classify these systems, then why are medicanes not classified? A strong medicane has all the tropical characturistics and mechanisms of a tropical system yet we discriminate against them. And sure they form in different environments, but so do Hurricanes vs Typhoons. A typhoon of identical strength to a hurricane tends to be about 15mb deeper than a Hurricane. Personally, and this may be ignorant beyond belief, but I think as long as it has a warm core and its mechanism for endurance is 100% convection based then why is it not a tropical cyclone?

 

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I see that Typhoon Koppu dumped 238mm on on location in the Phillipinrs in 6 hours and that some accumulated totals from the storm are expected to reach 1.5m (1500mm) of rain!

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I wish I hadn't been too busy to track that interesting feature Q, I'd say it has enough going for it to be at least subtropical. With such a large vertical temperature differential, air parcel buoyancy becomes sufficient for deep convection. Add in a decent moisture feed from the ocean and you're cooking!

That may be a bit simplified but I'm knackered after 10 hours hard work today 

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The transition seems to have begun (at last!), in the last few hours deepening has begun to occur, and the system is starting to look more tropical

Hint of an eye wall beginning to develop with cold cloud-tops only absent in the SE quadrant.  

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OK this has to be at least subtropical. Eye wall and eye clearly visible. Cloud bands are convective. Stormchaser?

 

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https://www.ipma.pt/en/otempo/obs.radar/

Would have expected more from the radar returns after seeing that sat pic though?

 

Incredible rainfall in Philippines - only heard of rainfall totals like that around Mumbai during the monsoon, or up around the top of the Bay of Bengal. We moan about our lack of interesting weather here but I guess it's not really such a bad thing  

 

 

Sorry Q it just looks like a good old fashioned storm to me, albeit in a slightly unusual location. I am not seeing an eye nor indeed an eyewall just a nicely defined circulation, with yes some convection.

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Indeed, at the moment it's just a mature cyclone - yesterday it had a classic Norwegian structure and today the fronts have occluded out and are wrapped around the circulation.

 

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It isn't unheard of for occluded lows to gain tropical characteristics, to me this low does not seem entirely extra-tropical anymore, the banding is more typical of a tropical cyclone than an occluded front wrapping into the LP, plus the cloud tops are colder and there is some convection going on. 

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I think its started to loose its tropical characteristics. I admit it was not fully tropical, but I don't think its fair to say that it was fully extra-tropical either, it was highly symmetrical, an eyewall type feature was observed and the banding did not just look like an occluded front. 

This is what a cold core occlusion looks like:

 

The cloud top is relatively warm and basically confined to a single spiral (where the occluded front is). However, this system had almost total cloudcover in the region surrounding the centre of the LP, plus one has to ask what mechanism caused the slight deepening earlier today? 

At the very least the system that we saw had some tropical characteristics, although was not as impressive as I would have hoped.

 

Looking at the IR satellite earlier

To me this seems very convincing, I just don't think an occluded front would make this sort of pattern, and in fact I'm not sure if you would even be able to see this because the cloudtops would probably be a lot warmer than is showing here. 

Do people seriously think they would be able to pick this out from a bunch of satellite photographs of tropical depressions? I'm skeptical, but like I say; probably a hybrid type system.

 

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The UK fax 12z analysis has this feature as just a spiraling occlusion, yet the DWD 12z analysis has the low slightly detached behind a warm front. Interesting one.

 

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Seems to have restrengthened again in the last few hours

Convection seems to still be going especially south of the centre. I'm sure this would be classified as a TD if it was in the 'right' place. Discrimination I tell ya!

 

 

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I like your enthusiasm Q and concur that on visible the feature looked quite 'tropical' at times. I await your research paper on medicines and other mis-represented tropical features with interest!

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There is already lots of cool stuff out there already nsrobins!

For example:

http://onlinelibrary.wiley.com/doi/10.1002/joc.3428/abstract

The impression I get is that there is no obvious reason why medicanes and their arctic cousins polar lows are not classified as tropical! Sure they may have slightly different formation mechanisms; for example polar lows initially use baroclinic mechanisms to mature howwever once in maturity it is doubtless that these systems are far more similar to tropical cyclones than mid-latitude depressions. On the subject of polar lows I read in some papers that its likely a true 'arctic hurricane' is not impossible, and does not occur only because their biggest formation ground in the atlantic arctic does not give them enough time before they hit land or encounter high wind sheer.  

 

This one in particular (one of the strongest ever recorded) would probably have developed into a full on catogary 1 hurricane were it not to have hit land so early.

 

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Speaking of medicanes, the WRF has been predicting one for a while now:

 

This is at its strongest!

 

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I think perhaps 'tropical' would have to become part of a parent category that includes the likes of Polar lows as otherwise it implies that there is tropical convection associated with those, which is a bit misleading.

We could just use 'baratropic lows' but for some reason that never seems to catch on?

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Except then Vince and Grace (fully classified tropical cyclones) would also have to be barotropic, given they initially formed out of cold core systems.

 

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Its seems to have reorganized again and now seems to pose a risk to Maderia

 A fascinating system in any case.

 Over the last couple of hours it has weakened dramatically after moving just to the north of these Islands. I think this is further evidence for tropical nature, a frontal system would not be so vulnerable to moving over land.

 

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Some amazing strengthening of Patricia over the past 12 hours - SLP measured at 894mb in the eye, with sustained wind speeds estimated at 180mph with gusts over 200mph. According to NHC:

"POTENTIALLY CATASTROPHIC LANDFALL IN SOUTHWESTERN MEXICO LATER
TODAY..."

Yikes.

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Indeed. Patricia has certainly surprised everyone with the rate of intensification exceeding the model guidance significantly.
One hopes the resorts on the SW Mexican coast are being evacuated now because this is not a board-up and sit it out situation - gusts near the eyewall will destroy buildings.

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Patricia does indeed look like a real monster. A very low (record of the E Pacific?) SLP and sustained wind speeds of 160knots - I wouldn't want to be in its path and I suspect it will be making a few headlines in the coming days.

The rate of intensification is remarkable and I suspect the very warm sea temperatures in that area have given it some oomph.

Edit: The latest update has Patricia with sustained wind speeds of 200mph and min pressure at an amazing 880mb. For an East Pacific hurricane (or indeed any cyclone) that is incredible. 

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It is indeed a new record for the E Pacific:
BULLETIN
HURRICANE PATRICIA ADVISORY NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202015
400 AM CDT FRI OCT 23 2015

...PATRICIA...
...THE STRONGEST EASTERN NORTH PACIFIC HURRICANE ON RECORD...
...POTENTIALLY CATASTROPHIC LANDFALL IN SOUTHWESTERN MEXICO LATER
TODAY...

SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION

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LOCATION...17.0N 105.5W
ABOUT 160 MI...255 KM SSW OF MANZANILLO MEXICO
ABOUT 235 MI...380 KM S OF CABO CORRIENTES MEXICO
MAXIMUM SUSTAINED WINDS...200 MPH...325 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...880 MB...25.99 INCHES

Repeat - maximum sustained winds of 200mph. That will produce gusts of 240mph easily. It's like an EF5 tornado only 50 - 100 miles wide around the eyewall. Truly incredible and with the expected storm surge of up to 8 metres I hope those guys near the coast are moving quickly away.
I fear this could turn out to be a major disaster for SW Mexico.

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NHC reporting that Patricia is now the strongest hurricane on record in the area that NHC monitors (Atlantic & Easter N. Pacific).

Spent a very pleasant holiday in Puerto Vallarta a few years back, looks like that resort is right in the firing line. Hopefully evacuations will be effective and minimise any loss of life.

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For a hurricane so strong it is rather small.. Hurricane strength winds only extending out to 30 miles from the core.