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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1626. Gearsts
Quoting wunderweatherman123:
center reformed i belive its at 13.8 north yesterday at 11pm 13.2 still not much latitude gain but its east of 11pm's coordinate points
Yea but they are not sure about the track yet and are expecting another shift west with the models.
Member Since: August 2, 2010 Posts: 0 Comments: 2000
Quoting stormpetrol:
Sames the more west Maria goes, the more north the cone is shifted, just saying..
center reformed i belive its at 13.8 north yesterday at 11pm 13.2 still not much latitude gain but its east of 11pm's coordinate points
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haha i hate being the negative one but the US got nailed by irene and lee. thats it. i think an average hurricane season has 2 hurricane landalls in the US. i saw the gfs 6z run maria out to sea, nate into mexico, carribean system into mexico, cape verde new system out to sea. right now its starting to become a pattern. i just hope texas gets one because they need it the most
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Sames the more west Maria goes, the more north the cone is shifted, just saying..
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1618. HCW
Quoting Fishaholic25fl:
What a boring hurricane season.....................


All it takes is one hitting you for it too quickly change
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Time: 10:53:30Z
Coordinates: 13.25N 59.1333W
Acft. Static Air Press: 512.5 mb (~ 15.13 inHg)
Acft. Geopotential Hgt: 5,681 meters (~ 18,638 feet)
Extrap. Sfc. Press: -
D-value: 282 meters (~ 925 feet)
Flt. Lvl. Wind (30s): From 228° at 15 knots (From the SW at ~ 17.2 mph)
Air Temp: -4.7°C (~ 23.5°F)
Dew Pt: -6.7°C (~ 19.9°F)
Peak (10s) Flt. Lvl. Wind: 16 knots (~ 18.4 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -
(*) Denotes suspect data
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Quoting stormwatcherCI:
That's what I think too.
They don't seem too secure in their forecast track and I could be wrong but she looks like she is still moving west although they say wnw.


I think they're almost expecting it when they get recon data later today.

Whatever happens, at the very least the models may start to tighten up.
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Thought i would put this out their of course i have no idea what it really means :)



Member Since: August 23, 2008 Posts: 0 Comments: 1918
What a boring hurricane season.....................
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Have a great day all - off to a conference and won't have a chance to even peek until after the 5pm comes out. Still watching the M track even though it doesn't seem likely to impact us here.
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Quoting shfr173:
What is that flair up in southern carrib?
Most likely the Colombian Low or the monsoon trough.


EDIT. I just checked the surface map and seems to be the southern end of a TWave over Haiti.
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1611. aquak9
Yep - Ellie says she is thankful I bought her that giant "GMU" umbrella that she thought was so tacky - it covers the 3 room mates all the way to the dining hall, LOL.


that's "mommy magic"

laterzzz
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Quoting aquak9:
ais- we got smoke here too occasionally, no idea it's source. But nothing like what TX has been going thru.

Hope your SanAn friends are ok.


I think people here are jumpy because we're an hour from Jasper, which has had multiple bad fires in the last couple of weeks. Everyone was calling everyone last night to see if anyone knew where the smoke was coming from. Texas needs that ridge out of there desperately.
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Quoting spinningtop:
sorry just fruastrated with all these wrong tracks with every storm


Thats why they compare hurricanes to well a spinning top :)

Member Since: August 23, 2008 Posts: 0 Comments: 1918
Aqua - forgot that's where Pros lives! Such a beautiful city, and George Mason is a lovely campus - especially for such an urban one.

Yep - Ellie says she is thankful I bought her that giant "GMU" umbrella that she thought was so tacky - it covers the 3 room mates all the way to the dining hall, LOL.

Seriously, they have had a ton of rain there this past week, and here in VB we've gotten only one brief heavy shower and some sprinklies.
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1607. shfr173
What is that flair up in southern carrib?
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1606. aquak9
ais- we got smoke here too occasionally, no idea it's source. But nothing like what TX has been going thru.

Hope your SanAn friends are ok.
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Quoting whepton3:


In Vegas terms, NHC is covering its bets.

Just read that discussion. It almost seems to me they're anticipating a model shift back to the more southern route next go round.

Forecasting the forecast models I guess.
That's what I think too.
They don't seem too secure in their forecast track and I could be wrong but she looks like she is still moving west although they say wnw.
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1604. aquak9
Quoting spinningtop:
sorry just fruastrated with all these wrong tracks with every storm


It's just computers doing math. Nothing to get "frustrated" over. Geeez you'll never handle being an adult if ya can't overlook the small stuff.

Just follow the NHC. Quit beating yourself up over the models.
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Quoting islander101010:
its a blog my character does not make the rules but characters can say what they need to say as long as its not offensive



wow, so early for some to be on. I love the mornings because it has people on who are all pleasant. Nothing wrong in asking someone why they are posting the same thing several times.
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Quoting Gearsts:
Maria found the Convectively-Coupled Kelvin Wave and she likes it :)


Dr. M nailed that one.

Of course, he nails a lot of stuff.

He probably forgot more about all of this today that most of us will never know.

He's the Godfather.
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1600. Gearsts
Maria found the Convectively-Coupled Kelvin Wave and she likes it :)
Member Since: August 2, 2010 Posts: 0 Comments: 2000
Quoting spinningtop:
sorry just fruastrated with all these wrong tracks with every storm

You think you can do better? Givit a shot
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Quoting whepton3:


In Vegas terms, NHC is covering its bets.

Just read that discussion. It almost seems to me they're anticipating a model shift back to the more southern route next go round... which of course they'll have some recon data to plug in over the next few runs.



Forecasting the forecast models I guess.
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Quoting aquak9:
spinning top- why do you just keep saying the same things over and over and over and over?
its a blog my character does not make the rules but characters can say what they need to say as long as its not offensive
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Quoting aquak9:
coops- fairfax? that's where my inlaws are. Gonna hafta get Rain to call Pros, or RainDad, today. Thanks for the bakonzzz..mmm crunch crunch

hi ais! yeah as soon as I saw the map this morning, I already knew what was gonna be nate's demise...so sad for texas...and w/la nina making a quick return, I don't see much hope for the future.

In 20 years, texas is gonna look like the MidEast...heck they already got the oil wells...


I got up this morning and the first thing I saw was the showers predicted for Monday yesterday were gone from the forecast. I knew then Nate wasn't going anywhere near Texas. Driving home yesterday I could smell smoke, but no idea where it was coming from.
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1595. HCW
Game Set and Match ?

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Quoting stormwatcherCI:
Good morning. According to the way the NHC worded the forecast discussion I do not think they are too secure in the forecast track.


THE OFFICIAL FORECAST HAS ALSO BEEN
SHIFTED TO THE NORTH BUT IT IS ON THE SOUTHERN EDGE OF THE NEW
GUIDANCE ENVELOPE IN CASE MODELS SHIFT BACK TO THE SOUTH IN THE
NEXT CYCLE.


In Vegas terms, NHC is covering its bets.

Just read that discussion. It almost seems to me they're anticipating a model shift back to the more southern route next go round.

Forecasting the forecast models I guess.
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1592. aquak9
spinning top- why do you just keep saying the same things over and over and over and over?
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Katia and Nate connected by what i see...
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1590. aquak9
coops- fairfax? that's where my inlaws are. Gonna hafta get Rain to call Pros, or RainDad, today. Thanks for the bakonzzz..mmm crunch crunch

hi ais! yeah as soon as I saw the map this morning, I already knew what was gonna be nate's demise...so sad for texas...and w/la nina making a quick return, I don't see much hope for the future.

In 20 years, texas is gonna look like the MidEast...heck they already got the oil wells...
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1587. luigi18
Quoting CaribBoy:


mm could be strenghtening


looks like a juyir.................
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Quoting barotropic:


All for positive here...but thats a incorrect statement. Floridas day is coming. Just a matter of time.
fl. needs to look sw. maria is a threat to the windwards it would take a hard right not to miss them now
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Good morning, all.

Aqua- Texas needs rain sooo bad. Just heard from friends north of San Antonio who have a fire near them and may need to evacuate.

CoopsWife, thank you, breakfast sounds wonderful!
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Quoting spinningtop:
im wondering if they will ever get the intensity and track of maria correct for a change been like 30 changes in the past 3 days
Good morning. According to the way the NHC worded the forecast discussion I do not think they are too secure in the forecast track.


THE OFFICIAL FORECAST HAS ALSO BEEN
SHIFTED TO THE NORTH BUT IT IS ON THE SOUTHERN EDGE OF THE NEW
GUIDANCE ENVELOPE IN CASE MODELS SHIFT BACK TO THE SOUTH IN THE
NEXT CYCLE.
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mm could be strenghtening
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G'morning, everyone. Just a quick peek before heading out this morning.

Coffee is on the sideboard, along with some (American) bacon and scrambled eggs.

Note re: Lee/front rains - the 3rd floor of my daughter's dorm at GMU (Fairfax, VA) had some slight flooding from heavy rain getting forced under the door sill - she claims she is now amphibious from all the rain this week. :)
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1577. aquak9
Quoting blsealevel:


Sounds like someone got frustrated
maybe they ought to think about a software upgrade

With all the budget cutbacks? They'll be lucky if they get new rulers and pencils.

G'morning all, sadly it looks like Nate will offer no relief to Texas, but no problems to anyone on the CONUS.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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