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Hurricane Maria


Jtm12180
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I believe the fastest moving Atlantic tropical cyclone on record was the 1938 "Long Island Express." It went from 30 N 75 W at 00z Sept 21 to 35 N 73.5W at 12z, near 40 N at 18z and made landfall on Long Island (41 N) at 21z. By 00z it was in southern VT at 43N. So it gained 13 deg of latitude while shifting about 2 deg east in 24 hours, and was travelling over 60 mph at some points. 

You have to wonder how well modern computer models would have handled it. 

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Maria's core has grown and expanded this evening. The old central vortex that passed over Puerto Rico is still easy to make out on shortwave, but appears devoid of heavy convection and looks to be weakening. It's probably going to take a while for the concentric intense convective banding producing current cold cloud tops to tighten up. That should get the core in a state conducive for any significant intensification. Right now the pressure and hurricane seems to be in a rather steady state. It also may need to gain some latitude from the Dominican Republic as close proximity can affect low-level inflow on the southern half of the circulation. Even if the larger eyewall/vortex tightens, Maria will probably have a large eye feature tomorrow.
092fbb6df909cef28573f860e0b41703.jpg

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The folks in Coral Gables at the NHC need to learn this as well.  I want everyone to take a moment and watch clips of Dr. Bob Sheets during Hugo and Andrew and remember what a strong leader and communicator he was.  Someone needs to go in and take control of the NHC and be able to go on tv during a major hurricane and be able to articulate a message.  


Hopefully the lesson was learned that cat 5s require perfect conditions over a very warm ocean to sustain. Throwing prolonged land interaction into that equation like irma over cuba and the core is permanently damaged. And irma was merely hugging that coast with 85 degree water literally within a stones throw from the eye, and she looked completely damaged within 6 hours. Maria looks better in structure exiting PR than irma skimming cuba but regardless maria weakened more than many thought. This topic would be a great reaearch study for a meteo grad student.
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13 minutes ago, LVLion77 said:


Hopefully the lesson was learned that cat 5s require perfect conditions over a very warm ocean to sustain. Throwing prolonged land interaction into that equation like irma over cuba and the core is permanently damaged. And irma was merely hugging that coast with 85 degree water literally within a stones throw from the eye, and she looked completely damaged within 6 hours. Maria looks better in structure exiting PR than irma skimming cuba but regardless maria weakened more than many thought. This topic would be a great reaearch study for a meteo grad student.

Most of the regulars here know this already. That's why cat 5 landfalls are extremely rare.

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2 hours ago, Paragon said:

What are the chances that Maria does what Jose is doing, and just stalls out offshore and loops around until the trough comes in and takes both Jose and Maria away?

 

I think current guidance has the general theme with Maria's track correct. I think this will be a much more typical track up the east coast than what we are seeing with Jose. The flow off the east coast will be faster, and there will be less blocking. Forecast wise, this is all about Maria's interaction with the trough. If the trough is flat and/or positively tilted she's likely ots...

The blocking over the northwest Atlantic will weaken considerably as Maria makes her way to the subtropics, and the trough eventually picks her up before she has too long to meander off the coast.

Teleconnection wise we want to watch the indices for the PNA and AO. Current forecasts indicate a +PNA and -AO, around the time that Maria is entering the subtropics. This teleconnection combination can act to enhance mid-latitude cyclone development, further amplifying the long wave trough upon its approach to Maria...

 

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44 minutes ago, LVLion77 said:


Hopefully the lesson was learned that cat 5s require perfect conditions over a very warm ocean to sustain. Throwing prolonged land interaction into that equation like irma over cuba and the core is permanently damaged. And irma was merely hugging that coast with 85 degree water literally within a stones throw from the eye, and she looked completely damaged within 6 hours. Maria looks better in structure exiting PR than irma skimming cuba but regardless maria weakened more than many thought. This topic would be a great reaearch study for a meteo grad student.

I feel it important to throw out that land interaction, especially higher terrain, has long been known to rip apart the inner core of hurricanes. Interacting with Hispanola is very often deadly to even well formed hurricanes, and they sometimes never recover. The problem with forecasting a hurricane's strength isn't that we don't remember that land will cause these reductions in velocity, but rather that the amount of land interaction is extremely important and hard to forecast. With the spread of the forecast track, it is often hard to know the amount of land interaction before impact with the island.

If the core stays offshore entirely, and the closest pass is brief, then there is often little or no reduction in strength. However, in the cases of both Irma and Maria, the interaction was more significant.

Additionally, if land interaction occurs during an eyewall replacement cycle, the disruption to the core is often significantly greater.

For Maria, the ERC had a defining role in the loss of power. Had the ERC completed (or not started) prior to landfall, we probably would have seen about a 1-2 category drop in power. Instead we saw an almost 3 category drop (from cat 5 just before landfall to boarder-line cat 4/5 at landfall (due to the ERC) to boarder-line cat2/3 at exit). The second issue with Maria was the longer track overland than models even 12 hours out were forecasting; this is likely partially due to land friction, but only through post-analysis will determine that. The original tracks had the storm hitting further north on PR and leaving land relatively quickly; even the models right at landfall had the storm tracking for a shorter distance overland.

In comparison, a fully formed eyewall (not undergoing an ERC) interacting with terrain for less time is what happened on Dominica - and it emerged still as category 5.

Since you also mentioned Irma, the tracks were half offshore, half onshore. Irma split the difference and the eyewall bounced along the shore. This resulted in significant loss of energy that it never recovered from. NHC had to assume the worst case when forecasting: that the storm would stay far enough offshore that its strength wouldn't be reduced. In other words, err on the side of worst case scenario because it's better to be over-prepared than under-prepared.

Back to reference land interaction during an ERC, if an ERC is occurring the outer eyewall has not fully taken over, and the inner eyewall is degrading, often rapidly. Impact with land (especially mountainous terrain) will cause the not fully established eyewall to become disrupted; this will cause the wind field to expand, which in turn causes the pressure to drop. An established eyewall will have less of an effect, though it can still be ripped to shreds by mountains, but it often takes more interaction for that to occur. 

We can very clearly see this affect of the expanding wind-field and pressure gradient with Maria. The central pressure has reduced to 961mb, but the gradient covers a much larger area. Compare the two following graphs, the top one current (broad gradient, but 961mb) and the bottom one when Maria was at it's peak (very sharp gradient, 905mb) - pay attention to the MSLP and Flight Level Wind lines in the top left graph - broader, lower pressure, but also much broader/stronger (but less intense at the eye) wind field:

 

Current Recon

recon_AF302-1115A-MARIA_timeseries.png

 

Yesterday's Recon (near storm peak, shortly before ERC started)

recon_AF303-0515A-MARIA_timeseries.png

 

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25 minutes ago, Random Chaos said:

I feel it important to throw out that land interaction, especially higher terrain, has long been known to rip apart the inner core of hurricanes. Interacting with Hispanola is very often deadly to even well formed hurricanes, and they sometimes never recover.

 

Hurricane David (1979) provides a classic example of how Hispaniola can damage intense hurricanes. David came ashore in the Dominican Republic with 150 knot winds. 18 hours later, it exited Hispaniola with 65 knot winds. Later it recovered somewhat with its maximum sustained winds reaching 85 knots, but it never returned to its earlier vicious state.

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3 minutes ago, donsutherland1 said:

Hurricane David (1979) provides a classic example of how Hispaniola can damage intense hurricanes. David came ashore in the Dominican Republic with 150 knot winds. 18 hours later, it exited Hispaniola with 65 knot winds. Later it recovered somewhat with its maximum sustained winds reaching 85 knots, but it never returned to its earlier vicious state.

There's a very interesting difference between land interactions of elevated areas vs flatter and marshier areas.  While a powerful hurricane can be humbled by higher elevations without even really making landfall there (by paralleling close to the shore), the same TC can actually maintain its energy or even strengthen over the marshier terrain of south Fla.

 

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2 minutes ago, Paragon said:

There's a very interesting difference between land interactions of elevated areas vs flatter and marshier areas.  While a powerful hurricane can be humbled by higher elevations without even really making landfall there (by paralleling close to the shore), the same TC can actually maintain its energy or even strengthen over the marshier terrain of south Fla.

 

Topography certainly matters. 

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Huge Flash Flood Emergency for PR now.

Flash Flood Warning
PRC001-003-005-011-013-023-027-065-067-071-081-083-093-097-099-115-
117-121-125-131-141-153-210645-
/O.NEW.TJSJ.FF.W.0092.170921T0340Z-170921T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Juan PR
Issued by National Weather Service Miami FL
1140 PM AST WED SEP 20 2017

...FLASH FLOOD EMERGENCY FOR MUCH OF NORTHWEST AND WESTERN INTERIOR
PUERTO RICO INCLUDING MAYAGUEZ AND AGUADILLA...

The National Weather Service in San Juan has issued a

* Flash Flood Warning for...
  Northwestern Sabana Grande Municipality in Puerto Rico...
  Las Marias Municipality in Puerto Rico...
  Lares Municipality in Puerto Rico...
  San Sebastian Municipality in Puerto Rico...
  West central Arecibo Municipality in Puerto Rico...
  Isabela Municipality in Puerto Rico...
  West central Adjuntas Municipality in Puerto Rico...
  Hormigueros Municipality in Puerto Rico...
  Moca Municipality in Puerto Rico...
  Northwestern Yauco Municipality in Puerto Rico...
  Quebradillas Municipality in Puerto Rico...
  Anasco Municipality in Puerto Rico...
  Northern Cabo Rojo Municipality in Puerto Rico...
  Camuy Municipality in Puerto Rico...
  Maricao Municipality in Puerto Rico...
  Mayaguez Municipality in Puerto Rico...
  Rincon Municipality in Puerto Rico...
  San German Municipality in Puerto Rico...
  Hatillo Municipality in Puerto Rico...
  West central Utuado Municipality in Puerto Rico...
  Aguada Municipality in Puerto Rico...
  Aguadilla Municipality in Puerto Rico...

* Until 245 AM AST

* At 1137 PM AST, satellite estimates and rain gauges indicated heavy
  rain falling across the warned area. Flash flooding is already
  occurring.

  This is a FLASH FLOOD EMERGENCY. This is a PARTICULARLY DANGEROUS
  SITUATION. SEEK HIGHER GROUND NOW!

* Some locations that will experience flooding include...
  Arecibo, Aguadilla, Aguada, Moca, Anasco, Camuy, Quebradillas,
  Hormigueros, San Sebastian, Las Marias, Cabo Rojo, Isabela,
  Mayaguez, San German, Lares, Hatillo, Rincon, Sabana Grande, Puerto
  Real and La Playa.

Excessive rainfall over the warned area will cause mud slides near
steep terrain. The mud slide can consist of rock, mud, vegetation and
other loose materials.
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3 hours ago, HarveyLeonardFan said:

The folks in Coral Gables at the NHC need to learn this as well.  I want everyone to take a moment and watch clips of Dr. Bob Sheets during Hugo and Andrew and remember what a strong leader and communicator he was.  Someone needs to go in and take control of the NHC and be able to go on tv during a major hurricane and be able to articulate a message.  

Dr. Rick Knabb as a past director of the NHC was really good too and now we get to enjoy him on TWC.  He emphasized from the beginning how bad the flooding problem with Maria would be and how flooding is the leading killer in TCs.  He's on there from 9 pm to 1 am ET.

 

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59 minutes ago, Z-Cast said:
Just read about massive flooding in Levittown in Toa Alta. Residents stuck on roofs as water rises. Sickening.

 

That rain gauge in Caguas registering 35 inches of rain in 24 hours is insane. That is tucked in a valley surrounded by mountainous terrain. I can't even imagine; that's really nothing short of terrifying.

 

e6102414479f67c42eecfebcaee5916a.jpg

 

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Looking at current trends in all the global models it looks like the only ones that will have to worry about this storm is the Turks and Caicos reigon.. Models have to have a major shift for this to be a east coast threat other than rough seas at this point...

Sent from my SM-G900R4 using Tapatalk

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3 hours ago, Windspeed said:

 

 

 

That rain gauge in Caguas registering 35 inches of rain in 24 hours is insane. That is tucked in a valley surrounded by mountainous terrain. I can't even imagine; that's really nothing short of terrifying.

 

e6102414479f67c42eecfebcaee5916a.jpg

 

Am I reading that right -- that Caguas got approx 10 inches in one hour between Sep 20 8:00 and 9:00?  OMG.

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47 minutes ago, BlizzardNole said:

Am I reading that right -- that Caguas got approx 10 inches in one hour between Sep 20 8:00 and 9:00?  OMG.

The convection has fired up again within the past couple hours with a band that has pushed back into the island from the west with some large blobs in it (plus lightning has ratcheted up as well - https://www.lightningmaps.org/?lang=en#y=18.1396;x=-66.5121;z=7;t=3;m=sat;r=0;s=0;o=0;b=0.00;n=0;d=2;dl=2;dc=0;) -

marie-WV-09212017.PNG

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From @HurricaneJosh

iCyclone 

Wednesday latenight (Puerto Rico): Yep, I'm alive. (Folks were wondering.)
Hurricane MARIA. Just... wow. The powerful Cat 4 (Cat 5 on the Oz scale) slammed into the SE corner of Puerto Rico very early this morning—and as it turned out, I was at Ground Zero.
* The chaserdude/weather-nerd perspective: These radar shots show I penetrated MARIA's violent inner eyewall and grazed the eye, at which time I recorded a whopping-low pressure of 929.4 mb. It was also around this time that the hotel started to blow apart, with windows smashing and pieces of the roof flying away.
* The human perspective: These women and child from across the hall came frantically knocking on my door at the height of the storm—their windows had blown out and they were in grave danger. I took them in and put them in the bathroom—the safest place in my room—and gave them pillows to cover themselves.
Fortunately, because of the direction they were facing, my windows did *not* smash (although they almost did).
The town I was in, Palmas Del Mar (in Humacao), took a real beating—as did the entire island of Puerto Rico. Even San Juan was hit hard.
I'll have my complete chase summary up tomorrow, and the video soon after. (I got some decent daytime eyewall footage in this one.)
More soon!

 

No automatic alt text available.

 

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11 minutes ago, bluewave said:

That is one of the biggest eyes in the Atlantic since Isabel.

It's not really a true eye. It's convection trying to wrap back around what's left of the original vortex. I think you will see it tighten up later today. The latest IR loop seems to show the beginning of this.

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9 minutes ago, NJwx85 said:

It's not really a true eye. It's convection trying to wrap back around what's left of the original vortex. I think you will see it tighten up later today. The latest IR loop seems to show the beginning of this.

It's a 40 mile punchhole type eye following the disruption going over Puerto Rico yesterday. 

Although the large, 40 n mi diameter, eye of the hurricane is still
a little ragged-looking, it is gradually becoming better defined,
and a ring of cold cloud tops is intensifying around the eye.
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8 am updates -

ZCZC MIATCPAT5 ALL
TTAA00 KNHC DDHHMM

BULLETIN
Hurricane Maria Intermediate Advisory Number 21A
NWS National Hurricane Center Miami FL       AL152017
800 AM AST Thu Sep 21 2017

...MARIA'S LARGE EYE PASSING OFFSHORE OF THE NORTHEASTERN COAST OF
THE DOMINICAN REPUBLIC...


SUMMARY OF 800 AM AST...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...19.9N 68.7W
ABOUT 95 MI...150 KM NNW OF PUNTA CANA DOMINICAN REPUBLIC
ABOUT 190 MI...305 KM SE OF GRAND TURK ISLAND
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...959 MB...28.32 INCHES

 

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