Derecho!

10 hours ago, Normandy said:

High rise structures in general are governed by the IBC section 202, which is an international building code that is adopted by local enforcing agencies.  The california building code (CBC 403.1) is derived from this code, and one can most reasonably believe Acapulco and other modern cities in the western pacific coasts in North America adopt this code.  In other words….there is no high-rise in a modern city that is not well built.

Now you might ask: well why is it so easy for a cat five to shred these well built buildings?  High rise structures are comprised of the following things:

1) interior vertical core of stair and elevator systems, with walls of concrete construction and fire rated up to 3-hours.  This core of walls cannot be destroyed by the hurricane and effectively act as a safe room for the building at each level

2) exterior curtain wall skin (typically comprised of cladded portions with mostly glazed systems).  This can be rated for higher end hurricanes, but typically winds exceeding 115 mph can send airborne debris that can puncture these glazed panels.  This is why you often see high rise windows missing here and there when a major hurricane strikes a major city (ie New Orleans in Katrina, Wilma in Florida).  Outright failure of these systems require winds exceeding 145 mph.

3) interior demising unit walls (non structural connections to the deck and only rated for sound and impact).  These wall are food for winds greater than 115 mph as they offer no structural connections at the top and bottom to deal with wind pushing against them.  Once the wind rips the exterior skin off the high rise, the interior walls are just blown over and out where the wind is inside.  

The structure and core survive but the spaces around it around completely gutted and shredded.  Has nothing to do with being well built.  The structures still standing imply they are well built and code compliant.

Takeway is that it is not feasible from a cost perspective to build high-rises in areas such as this that could survive a storm such as this  without massive damage, that people would actually want to live in (given the point of a high-rise on the beach is the view). 

2 hours ago, GaWx said:

 But then again why go with any operational in particular? Why do we need a definite yes or no when neither is there this far out and instead why not just go with the idea that Lee bears watching for the continued small chance of a NE hit and a bigger chance for a Canada hit? This is a forecasting discussion. We have these discussions because of the uncertainty. 

Eh, it's a Snow Weenie perspective, where consensus models don't exist and it's some sort of titanic picking-sides model fight. 

24 minutes ago, Ed, snow and hurricane fan said:

It looks like even the GFS ensembles are down to 2 (1 NY, 1 Maine/Canada border) with US landfall.  Through hour 180, but I think that shows the only US landfalls the GEFS are going to show

? There are Six (CT, MA, 4 in Maine). 

7 minutes ago, Hotair said:

Ok it was not clear from previous response that it would actually break the model if they used real values.  It just seemed like a capricious choice 

Think about and ECMWF model run predicting a tornedo outbreak. The air pressure within an individual tornedo might be 850 mb; when you look at the model run you aren't going to see any 850 mb pressures within actual tornadoes - tornadoes are far tinier than the 9 km grid spacing of the ECMWF. 

4 minutes ago, Hotair said:

Initialized Lee at 991 mb Where  do they get these #s ?  

 

Was already explained to you earlier in the thread. Global models lack the resolution (and it's worse the less sophisticated they are, like the GEM)  to deal with the pressure differentials across small distances from a tropical cyclone.  Would break the model with a true pressure init. 

2 hours ago, Hotair said:

Can someone here care to explain the rationale for the models initializing using much higher pressures than what recon measured ? 
 

 

 

 

 

 

 

 

 

Mike's Weather Page

 

@tropicalupdate

·

1h

 

Recent models initializing way higher than actual. EURO 983mb, GFS 966mb, CMC 996mb, ICON 999mb. HAFS/HMON seem accurate. Odd?

The main differences between the last two GFSes is speed; 12Z is slower. 

1 hour ago, Eskimo Joe said:

GFS trying to turn Idalia back into the southeast at HR 168?

Loops back into the Gulf (never intensifies) and wanders over New Orleans at HR 222. 

Last NOAA Dropsonde is labeled "SE Eyewall"

Having been to the Salton Sea a few years ago:

1) everything near it on the North, West, and East sides has been abandoned so there's nothing to destroy. Very flat area so even minor increases in lake level will radically increase side

2) The problem is the Imperial Valley to the immediate South; this is below sea level and is one of the most important agricultural areas in the country and fairly densely populated. I could imagine a vast area being flooded with moderately salty water which would be pretty disastrous.

Remember the Gulf of California used to extend all the way to the Salton Sea fairly recently in geologic time. It was cut off by the Colorado River Delta sediments. 

I realize no one reads anything but regional forums anymore but ECMWF just opened up a lot more data for free: posted on the main forum.

https://www.ecmwf.int/en/about/media-centre/news/2022/ecmwf-makes-wide-range-data-openly-available  

Always found it odd how restrictive they were

38 minutes ago, bluewave said:

The 12z NAM has hurricane gusts over Eastern Long Island. Very tight core so strongest winds don’t  get far from center. This is one of the more compact systems to affect  our area. So the exact track is very important. 


 

For the love of God, the NAM shouldn't even be mentioned, much less have maps posted. 

You know less about a tropical system forecast after looking at the NAM than you did before.  It's literally negative (value) information. 
 

it is so wierd the Philly board doesnt even have a SVR thread. And they would have 100 times the posts for a quarter inch of flurries than a PDS tornado.

Just now, kayman said:

Tighten couplet on the relatively velocity for the western Tuscaloosa County supercell...

Is that even warned yet? 

1 minute ago, WVclimo said:

The 12k NAM output for here matches February 14, 2007.  3-6" of snow then 3" of sleet before a quarter-inch of freezing rain.  That one was one of the most impactful winter storms I've seen here. Only time I could walk on top of snowpack without breaking through. Just a surreal scene.

1993 Storm of the Century I was in New Jersey. I could JUMP UP AND DOWN on the ice without breaking through to the snow. 

Just now, SnowenOutThere said:

why?

There seems to be a belief that starting a storm thread is a jinx. 

52 minutes ago, Albedoman said:

I am a physical geographer. Meteorology snow maps mean exactly shite if you do not understand the concept of the data and how it is placed on the map in the first place. I love when these idiots draw up a snow map and have no fricking clue on the basics of how a storm forms and operates in the eastern US.  Clown snow maps are estimates anyways and should only be used to as a reference to meteorologists where the heaviest snowfall may occur. This reference is directly related to the last storm event where the Lehigh Valley continually was placed in the jackpot zone on almost every model while everyone was wishcasting these same amounts over their house in all the forums.  Go to where the heaviest snowfall is predicted continually over several models runs and the forecast can be fine tuned from there for storm totals. Clown maps also usually do not take the mean but the extreme-- that should be the motto when reading these maps.   What did I get?  32 inches of snow- several models spit out insane amounts between 40 - 55 inches but I did not run with them-. The point was that the Lehigh Valley was the target area and most models were spot on.

A worse and more dangerous atrocity is something I routinely see on social media - for hurricanes "Spaghetti Model" maps that have UNLABLED tracks and show every "model" (to include the extrapolated track, and ancient, obsolete models not actually used like LBAR, etc). It of course shows a wide spray and is typically accompanied by "LOL nobody knows where it is going could hit anywhere" comments.

Of course the 6-7 models that actually matter are now routinely on top of each other, even out to 5 days, and TC track forecasting has gotten incredibly accurate. but these maps show 50 unlabeled "model" lines all the same color.

53 minutes ago, frd said:

What in the world made accu weather jump the gun forecasting , even though two options were presented, that a huge snowstorm would hit the East Coast ? 

It never was even close .

 

Because the benefits are so high (if there is one, crowing press release about how they are better than the NWS and called it well ahead of time ) and the downside so low (if there isn't one, basically a handful of people on this board or like them even notice or care). 

4 minutes ago, BTRWx's Thanks Giving said:

or extrapolating radar heading towards you

Actually began with tropical weenies imagining hurricanes making un-forecast turns towards them. 

42 minutes ago, olafminesaw said:

Is it possible that the reason Eta was weaker than satellite suggested because of how far south it is? I don't know much about the physics of hurricanes, but I ask because I was wondering if the coriolis effect only played a role in development or also in maintaining intensity

No, not at all. In other basins extremely powerful tropical cyclones occur closer to the equator than Eta. Haiyan was 4 degrees closer to the equator than Eta, for example. 

And even the development thing is a myth - the Atlantic is the oddball basin in having so little development close to the equator - and that's because the ITCZ is so far north in the Atlantic during tropical season  not a  "lack of Coriolis." 

OP GFS now hits Nantucket, Cape Cod, and Northeast tip of Maine at 950 mb.

5 minutes ago, TradeWinds said:

The flip flop continues for the potential storm end of Oct. EPS pretty much all out to sea. 

 

 

Para looks like it ends up in Texas. 

Just now, cptcatz said:

I mean from a meteorological standpoint. These two runs might be the craziest path I've ever seen a model show a hurricane take.  Is it actually possible?

Of course it's possible. TCs have done all sorts of insane things - stalls, loops, zigs, etc. 

11 hours ago, Maestrobjwa said:

A track often modeled, but only verified what...3-4 times in history? Lol But this is 2020!

I suspect over a period of thousands of years this is a very common track, it had just been rare very recently.