Nate almost a hurricane; Maria remains disorganized

By: Dr. Jeff Masters , 9:05 PM GMT on September 08, 2011

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An Air Force Reserve hurricane hunter aircraft is in Tropical Storm Nate, and has found winds much stronger than the storm's satellite appearance would suggest. At 2:17 pm EDT, the aircraft measured winds at their flight level of 1500 feet of 93 mph, which would ordinarily support upgrading Nate to a Category 1 hurricane. Surface winds measured by the SFMR instrument were about 70 mph, suggesting that Nate is indeed very close to hurricane strength. However, latest visible satellite loops show that if Nate is a hurricane, it's only half of a hurricane. Nate's low-level center is exposed to view, due to northeasterly upper-level winds that are creating a moderate 10 knots of wind shear. This shear is keeping all of Nate's heavy thunderstorms pushed to the south side of the center, and the northern half of the storm almost cloud-free. Sustained winds at Buoy 42055, about 140 miles to the northwest of the center of Nate, were just 28 mph at 3:50 pm EDT this afternoon. Water vapor satellite loops show that there is a large area of very dry air from Texas to the north of Nate, and this dry air is keeping the northern half of the storm dry.

Nate will meander in the Bay of Campeche for several days, and the computer models are sharply divided on what happens early next week to the storm. A ridge of high pressure is expected to build in to the north of the storm, potentially forcing it westwards to a landfall in Mexico. However, our two best-performing models last year, the GFS and ECMWF, predict that a weak trough of low pressure expected to move across the U.S. early next week will be strong enough to turn Nate northwards towards an eventual landfall along the northern Gulf Coast. We will have to wait until the NOAA jet makes its first mission to sample the steering currents in the Gulf of Mexico to get a better idea on how probable this northern path might be; their first flight will be tonight, and the data will make it into the 8 pm models runs that will be available first thing Friday morning. As far as intensity goes, the very dry air to Nate's north should begin being less of a problem for it by Friday, when the upper level winds shift more to blow from the southeast, and the shear drops to the low range, 5 - 10 knots. Since the storm is moving very slowly, it will upwell cooler waters from the depths that will slow intensification, though.


Figure 1. Afternoon satellite image of Nate.

Tropical Storm Maria
Tropical Storm Maria barely survived as a tropical storm today, but is now making a bit of a comeback. Satellite loops show that Maria has been badly ripped up by the 10 - 20 knots of wind shear affecting it. The low-level center has been exposed to view most of the day, and surface arc-shaped clouds have been racing away from the storm to the west this afternoon, indicating that dry air has been getting into Maria's thunderstorms and disrupting the storm. However, the areal coverage and intensity of Maria's thunderstorms have increased a little in the past two hours. Maria is passing close to buoy 41040, which measured sustained winds of 36 mph, gusting to 45 mph, at 2:50 pm EDT.

Wind shear is predicted to fall to the low range on Friday as Maria approaches the Lesser Antilles. In addition, as I noted in this morning's post, Maria will be encountering an atmospheric disturbance known as a Convectively-Coupled Kelvin Wave (CCKW) that is currently passing through the Lesser Antilles Islands. There is a great deal of upward-moving air in the vicinity of a CCKW, and will help strengthen the updrafts in Maria's thunderstorms, potentially intensifying the storm. None of our models are detailed enough to "see" CCKWs", so we may see more intensification of the storm than the models are calling for. I believe Maria will continue to organize and arrive in the Lesser Antilles Islands as a tropical storm with 50 - 60 mph winds. The latest run of the GFDL model predicts that Maria will be a Category 1 hurricane on Saturday afternoon when it moves through the Virgin Islands, and a Category 2 hurricane Sunday night when it moves through the Turks and Caicos Islands. This is on the high end of what is possible, and I think it more likely that Maria will be a tropical storm with 50 - 60 mph winds in the northern Lesser Antilles, 60 - 70 mph winds in the Virgin Islands and Puerto Rico, and a Category 1 hurricane in the Turks and Caicos Islands--assuming passage over Puerto Rico and the eastern tip of the Dominican Republic does not significantly disrupt the storm. A lower intensity, as forecast by NHC, is certainly quite possible, as Maria may continue to struggle with the dry air and wind shear besetting it.

The latest computer model runs have been trending more southwards, and the Northern Lesser Antilles, Virgin Islands, Puerto Rico, the Turks and Caicos Islands, and the Bahama Islands are all at high risk of a direct hit by Maria. The models are split on how strong the steering influence a trough of low pressure along the U.S. East Coast will have once Maria approaches the U.S. East Coast. Most of the models foresee that Maria will turn north before arriving at Florida, and potentially threaten North Carolina, Bermuda, or Canada. The latest run of the GFDL model, though, brings Maria through the Bahamas to a point just 100 miles southeast of Miami as a hurricane on Tuesday afternoon. While this forecast is an outlier, and it is more likely that Maria will turn north before reaching Florida, it will be another two days before we will have a fair degree of confidence on when Maria will curve to the north.

Lee's rains trigger historic flooding in New York and Pennsylvania
An extreme rainfall event unprecedented in recorded history has hit the Binghamton, New York area, where 7.49" of rain fell yesterday. This is the second year in a row Binghamton has recorded a greater than 1-in-100 year rain event; their previous all-time record was set last September, when 4.68" fell on Sep 30 - Oct. 1, 2010. Binghamton has also already broken its record for rainiest year in its history. Records go back to 1890 in the city. The rain has ended in Binghamton, with this morning's rain bringing the city's total rainfall for the 40-hour event to 9.02". The Susquehanna River at Binghamton has risen to 25.69', its highest level since records began in 1847, and is now spilling over the flood walls protecting the city, according to media reports. In Hershey, Pennsylvania, Swatara Creek is 19' over flood stage, and more than 9' above its record flood crest. Widespread flash flooding is occurring across the entire area, and over 120,000 people have been evacuated from their homes.


Figure 2. Seven-day precipitation amounts from Tropical Storm Lee and its remnants. Image credit: NOAA/AHPS.


Figure 3. The Susquehanna River at Binghamton has crested this afternoon at its highest flood height on record, 25.69'. Records at this gauge go back to 1847. Image credit: NOAA/AHPS.


Figure 4. In Hershey, Pennsylvania, Swatara Creek is 19' over flood stage, and more than 9' above its previous record flood crest. The river is forecast to crest at 27.2' (green lines are the predictions.) Records at this gage go back to 1930. Image credit: NOAA/AHPS.

The extreme rains are due the the remains of Tropical Storm Lee interacting with a stationary front draped along the Eastern U.S. Adding to the potent moisture mix last night was a stream of tropical moisture associated with Hurricane Katia that collided with the stationary front. You don't often see a major city break its all-time 24-hour precipitation record by a 60% margin, according to wunderground's weather historian, Christopher C. Burt, and he can't recall ever seeing it happen before. It's worth noting that the Susquehanna River Binghamton stream gage, which has been in operation since 1847, is due to be shut off in 3 weeks due to budget cuts. Here's the note at the USGS web site:

NOTICE (03/23/2011)--Data collection at this streamgage may be discontinued after October 1, 2011 due to funding reductions from partner agencies. Although historic data will remain accessible, no new data will be collected unless one or more new funding partners are found. Users who are willing to contribute funding to continue operation of this streamgage should contact Rob Breault or Ward Freeman of the USGS New York Water Science Center at 518-285-5658 or dc_ny@usgs.gov.

I'll have an update in the morning.

Jeff Masters

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Quoting twincomanche:
Our Dear Leader is done. Let the football begin!!!!


Well, he wanted to speak last week, but this is the only date the republicans were available.
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...NATE NEARLY STATIONARY IN THE BAY OF CAMPECHE...
7:00 PM CDT Thu Sep 8
Location: 19.7°N 92.2°W
Max sustained: 70 mph
Moving: Stationary
Min pressure: 994 mb
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Quoting AllyBama:


OMG!..that is more than I needed to know!..ROFL


I believe Dak was referring to the lid. :)
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Quoting MississippiWx:

StormW agrees with your forecast. So, if you're wrong, you can both go down together. LOL.

For what it's worth, I am still thinking your forecast makes the most sense, so I'll go down with you as well. We'll see.




When it comes to track forcasts, it's hard to bet against the NHC. Anybody that goes against them has big brass ones!
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And you gotta love CNN....

Specific, Credible, Unconfirmed and Non-Detailed threat against the US...

Ok... That helps.
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Who thinks Lee may get retired?
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Wow Nate 5 days outt barely moving and they have no idea where it's going an a cat 2 that is some rocket fuel in the BOC will lee or it's energy ever leave, can you say emi em emil emi uggh I can't say that name but possibly something like that horrible thout
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Got some updates from Pennsylvania. There are hundreds of trucks and cars stranded on Route 17 (I86). Most of it is closed and the drivers can't get out. The townspeople are bringing them food and fresh water. They don't know how long they will be there. The flooding is much worse than anything they have ever experienced. The water level is beginning to rise over the levis in Binghamton.
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Hi Grother - so good to see you back posting again and taking care of the crew.
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Hello Grother, glad to see around.
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Quoting Grothar:


Not there yet, Levi, but thanks. What is with these models? Looks like there is no consistency. Well, I guess as Emerson wrote, "A foolish consistency is the hobgoblin of little minds". They better get going because it is confusing looking at the changes they make every update.


Hey Gro.
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Quoting Grothar:


Not there yet, Levi, but thanks. What is with these models? Looks like there is no consistency. Well, I guess as Emerson wrote, "A foolish consistency is the hobgoblin of little minds". They better get going because it is confusing looking at the changes they make every update.


Well I hope you fully recover soon...

I both love and dread these wild situations. It provides a great opportunity to make a forecast without as much bias towards the models, but it also means a larger chance of being dead wrong lol.
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463. jpsb
Quoting blsealevel:


Had them on ice and salt from this morning nice and cold

Temps this morning was close to 60 F to bad this is fixing to change back to the muggies :)
I am enjoying this early norner too, great weather, but I would trade it for a hard rain in a NY second. I've got my fingers crossed that Nate might bring us a little rain here in se Texas. Maybe he can hang in there long enough for remnant Lee to go west and open up a path for him to come there. lol, wish casting, but hey it could happen.
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Hey Gro, nice to see you back. :)
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Courtesy: NASA/Goddard Space Flight Center Scientific Visualization Studio

'Towers in the Tempest' is a narrated animation that explains recent scientific insights into how hurricanes intensify. This intensification can be caused by a phenomenon called a 'hot tower'. For the first time, research meteorologists have run complex simulations using a very fine temporal resolution of 3 minutes. Combining this simulation data with satellite observations enables detailed study of 'hot towers'. The science of 'hot towers' is described using: observed hurricane data from a satellite, descriptive illustrations, and volumetric visualizations of simulation data. The first section of the animation shows actual data from Hurricane Bonnie observed by NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft. Three dimensional precipitation radar data reveal a strong 'hot tower' in Hurricane Bonnie's internal structure.

The second section uses illustrations to show the dynamics of a hurricane and the formation of 'hot towers'. 'Hot towers' are formed as air spirals inward towards the eye and is forced rapidly upwards, accelerating the movement of energy into high altitude clouds.


The third section shows these processes using volumetric cloud, wind, and vorticity data from a supercomputer simulation of Hurricane Bonnie. Vertical wind speed data highlights a 'hot tower'. Arrows representing the wind field move rapidly up into the 'hot tower, boosting the energy and intensifying the hurricane. Combining satellite observations with super-computer simulations provides a powerful tool for studying Earth's complex systems.



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460. HCW
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Quoting Dakster:


If I couldn't lift anything heavy I would have trouble going to the bathroom...


OMG!..that is more than I needed to know!..ROFL
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..wait for it.
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TS Nate Low angle

Storm Relative 1km Geostationary Visible Imagery

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Quoting splash3392:
446

that was good Dak! LOL

Press you left yourself wide open!


oh yea...I usually do ;-)
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Not exactly a world-beating structure:

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446

that was good Dak! LOL

Press you left yourself wide open!
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Quoting Dakster:


I was going to ask about Nate too... but nevermind...


He has been in the French Quarter...
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Quoting Levi32:


Grothar, great to see you are well!


Not there yet, Levi, but thanks. What is with these models? Looks like there is no consistency. Well, I guess as Emerson wrote, "A foolish consistency is the hobgoblin of little minds". They better get going because it is confusing looking at the changes they make every update.
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What is the GFS model smoking for Nates path lmao.........
Member Since: August 22, 2011 Posts: 0 Comments: 162
Quoting presslord:


How do you know about her?!?!?!?!?!?!?! oh...wait...you meant the storm.....nevermind...


I was going to ask about Nate too... but nevermind...
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Quoting presslord:


Pat....I was really disappointed...not much of a flick at all...


I saw the reviews and passed.

Im a Apollo detail Nut so I would have p-oed the audience anyway.

Maybe gotten Banned or sumthing.

: )
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Quoting jpsb:
Time to pop a cold one.


Had them on ice and salt from this morning nice and cold

Temps this morning was close to 60 F to bad this is fixing to change back to the muggies :)
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Quoting P451:
If there is one thing you can really say about Nate it's that he is struggling to sustain any deep convection with cold cloud tops.

This is a very weak convective signature for a tropical storm let alone a 70mph one.

One lone top of -70C (red). Very few -60C tops (green). Primarily -50C's (dk blue).

All I can think of is far more dry air is creating problems for this storm than generally thought.




For comparison sake, here's Maria:



While she is a highly disorganized system I put it up to show what deeper convection looks like on the enhanced imagery. Lots of -70Cs (red) and some -80Cs (yellow) are evident.


Being halfway on land probably isn't helping, either :)
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Quoting Dakster:
Presslord - How goes it?

Ready for Maria to come visit you?


How do you know about her?!?!?!?!?!?!?! oh...wait...you meant the storm.....nevermind...
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Quoting PcolaDan:


What, someone exposed themselves on here? :O


Beat it chickendan.

Dewey is replacing you with a new dan anyway.
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Quoting Patrap:


I could have gotten you and Me to the Moon and Back with what they spent to make Apollo 18, Shucks, I got a Saturn V S-1 First Stage a few miles away just laying on the tractor wheels.

We could of left a Weather Station for wu, too.




Pat....I was really disappointed...not much of a flick at all...
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Presslord - How goes it?

Ready for Maria to come visit you?
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Quoting FLdewey:


Might help your forecasting skills.


How's your Gang tonight?
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Quoting presslord:
just saw Apollo 18...really wish I'd spent that money on crack, instead....


I could have gotten you and Me to the Moon and Back with what they spent to make Apollo 18, Shucks, I got a Saturn V S-1 First Stage a few miles away just laying on the tractor wheels.

We could of left a Weather Station for wu, too.


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Quoting Grothar:


Well, I am not supposed to lift anything heavy, but here you are:



Grothar, so glad to see you back! Can those systems/waves South of the equator move Northerly and become a future threat top Carib/CONUS or does their present position prevent that happening?
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Quoting PcolaDan:

He's picking on me!!!!!


He only picks on bloggers he likes.

I don't buy this yet.

img src="">
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just saw Apollo 18...really wish I'd spent that money on crack, instead....
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Quoting DFWjc:


wait if we can take Pluto out of the planets classification, why can't we take a tomato out of fruits?

Science confuses me.... :(


And how come Pluto can't talk but Goofy can?
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.