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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Maria is loving the Kelvin wave.

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Quoting Chicklit:


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. -- Jeff Masters



Not sure what would show this Aussie but she looks pretty fired up and Dr. Masters is usually right.



When you hold a position of authority, and you're often right, sadly you'll get criticized a lot, probably because people are jealous. Its crazy how often people criticize Dr. Masters on his own blog. He writes huge blogs, so yeah sometimes he might write a misprint or *GASP* make a mistake so people go crazy and question his ability... Why are people so darn critical of others???
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"Nate" is really getting on my nerves. The biggest Texas tease ever! The 7 a.m. NHC track is just downright depressing, especially after the "hope" track of yesterday.
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fpl ad on this weather underground i use less than last yr acc/ to their figures and pay more. as for weather its is getting that time of yr for the sw carib to perk up and look could there be something there soon? maria it looks unless she makes a hard right prico is in harms way good luck boriquens
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1920. kwgirl
Good morning all. Why are we fascinated by extreme events? I spent most of last night watching TWC. Yes, they have a lot of hype, but they are covering the flooding in the NE and it is amazing to me to see the flooding. My heart and prayers go out to all the people affected by floods. I went through it in Wilma and realize how lucky we were in the Keys to get a gentle rise of the ocean, rather than a thundering torrent of muddy water. I keep thinking, though no one wants them, that the disasters this year will put a lot of people to work. Watch what you wish for....
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1919. WxLogic
For now... I wouldn't expect much of a northerly component to Maria for a while:

Member Since: August 14, 2008 Posts: 4 Comments: 5038
1918. Caner
Nate finally starting some western movement in latest sat images, after a jog to the N/NE.
Member Since: June 27, 2011 Posts: 0 Comments: 179
1917. will40
When using Dr. Masters' blog, please refrain from posting material not relevant to the discussion of tropical weather, or the topic of the blog entry itself. Please do not engage in personal attacks or bickering. Material not conforming to these standards should be flagged with the button and ignored.
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Cluster of thunderstorms heading toward Tampa Bay.
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1915. Hoff511
Quoting Hawkeyewx:


I don't think you will find many weather enthusiasts like us who want to see anything but full funding given to the NWS/NHC. We realize how important things like upper-air-sampling recon missions, stream gauge maintenance, etc. are. This is certainly an important topic of discussion.

Posters just need to remember that terms like "faux news" and "pmsnbc", et al, are red flags. The rest of the post may be filled with exceptionally intelligent commentary and important links, but political red flag terms will have some of the readers immediately skipping to the next post without reading yours.


+100
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1912. TheMom
Quoting Chicklit:

Or maybe exuberant!
Sure will be an interesting day.
Note the blob off the east coast of Florida, and Nate isn't even in this picture!
LinkIRLoop
Gottago.
Blob off Florida looks like our regular 5pm on Friday rain ;-)
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Considering it is almost mid-September, let's examine the Arctic ice extent trends:



Tropical storm Nate will be in a line of Bay of Campeche mini-storms and mini-hurricanes that bring severe weather to a small area: Marco 2008 and Karl 2010. Not much relief for Mexico's drought.

Meanwhile, Maria is a very large storm currently encountering dry air, and spans about 10 lat/lon degrees across. Although it is currently in the MDR, at a low latitude, it is still extremely large. Since storms typically expand as they head north, dangerous rip currents could be in store for the Bahamas, Florida and the US East Coast.
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Quoting AussieStorm:

Could be worse, you could be here, was a 55°F here and got 0.22" of rain today.


What I would give for 50s and some nice rain right now. Warm/hot and muggy as usual here.
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I feel as long as the military relies on our weather forecasting capabilities I don't see a major cut in NOAA, etc.

They will do like they do in every aspect of politics. They will show a cut in funding, but just shuffle it around in a different department, or name.
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Quoting Chicklit:

Or maybe exuberant!
Sure will be an interesting day.
Note the blob off the east coast of Florida, and Nate isn't even in this picture!
LinkIRLoop
Gottago.

Enjoy your day, I have enjoyed mine. Pity it rained all day and was only 55F. Especially when we had 78.3F here on Tuesday.
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Quoting ElConando:


Is it 1993 Mississippi river flood bad?

My parents picked the summer of 93 to take my brother and I on a cross country road trip, and we had to come back in a hurry before it became impassable.Remember looking out the car window on the way back while we were going over a highway bridge and seeing the Mississippi river starting to climb the trees on the bank below.Hope for the sake of the people up North that it's not that bad,but from some of the stories I've heard,it's going to be close.
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1905. JNCali
mornin' all.. Still looking for Maria to get her act together over the next 36 hours. Nate.. he's just a tease, wish he'd just get of his butt and head somewhere!
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Here's Nate IR Loop:
Link
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Quoting kilgores97:


Aussie, why are you so dependent upon the government to get you your weather? In the true spirit of American inginuity, if NOAA gets funded, what is stopping private industry from stepping up and filling the void? Oh yeah, government red tape and regulations.

Sorry everyone for posting an opinion piece, Just thought I would bring it to everyone's attention. I will refrain from posting any further information.
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1900. Caner
>.<

Think i'm going to head over to the Real Clear Politics blog and discuss tropical weather systems for awhile.
Member Since: June 27, 2011 Posts: 0 Comments: 179
Unhid a few people today and now I regret it. Someone needs to start a seperate blog where the funding of NOAA etc. can be discussed before I blow my top and get banned.
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Quoting lickitysplit:


I know! So much irony since Bill is ALL spin!


At least it's entertaining!
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Quoting AussieStorm:

She does look very angry.

Or maybe exuberant!
Sure will be an interesting day.
Note the blob off the east coast of Florida, and Nate isn't even in this picture!
LinkIRLoop
Gottago.
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retire lee too
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Nate fistbumps Katia.
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Quoting Chicklit:


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. -- Jeff Masters



Not sure what would show this Aussie but she looks pretty fired up and Dr. Masters is usually right.

She does look very angry.
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1891. 3211976