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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BULLETIN
TROPICAL STORM NATE INTERMEDIATE ADVISORY NUMBER 7A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL152011
700 AM CDT FRI SEP 09 2011

...NATE DRIFTING NORTHWESTWARD...


SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...20.0N 92.4W
ABOUT 125 MI...200 KM W OF CAMPECHE MEXICO
ABOUT 180 MI...290 KM NE OF COATZACOALCOS MEXICO
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES
Member Since: July 6, 2010 Posts: 113 Comments: 32024
"Hurricane Katia off the east coast of the US could cause stormy weather to hit Scotland on Monday, according to forecasters in Miami.

John Cangialosi, at the US National Hurricane Center, told the Reuters news agency that Katia was expected to head out into open sea.

He said it would change from a tropical storm to a "classic wintertime storm" by the time it reached Scotland.

The Met Office has not issued a severe weather warning at this stage.

However, Northern Constabulary said the Met Office had forecast heavy rain and severe gales for large parts of the north of Scotland on Monday.

Hurricane specialist John Cangialosi said Katia would change from a tropical system to a larger storm once it was over open sea and would head for Scotland.

He said: "It'll likely be a very big, significant weather system.

"It will evolve into a classic wintertime storm by the time it gets there."

Link

A warning from the NHC, an article on the BBC about Pat Tillman who tragically died in the line of duty and a lot of coverage on the upcoming 9\11 anniversary.

A very American touch here as of late.
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Quoting Relix:
I believe Maria will make landfall around Ponce, PR.


It may be possible but what do you base your opinion on?
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Quoting JRRP:
i think
13.9n
57.2w
Link


I concur.
Member Since: July 6, 2010 Posts: 113 Comments: 32024
Sorry Puerto Rico...even if you guys miss a direct hit...guess what you get? Rain...Rain...and more Rain.

Member Since: July 6, 2010 Posts: 113 Comments: 32024
1668. JRRP
i think
13.9n
57.2w
Link
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Quoting cat5hurricane:

Just having a little fun. No reason to take it so personally :-)


Ok :P
Member Since: July 6, 2010 Posts: 113 Comments: 32024
Quoting cat5hurricane:
So, is Nate still going to the Florida Panhandle?

LMAO


Why are you laughing at everybody's opinion? That's the reason we argued with you the other night. There is no reason to "LMAO" at somebody's opinion.

Member Since: July 6, 2010 Posts: 113 Comments: 32024
Good Morning.

Don't let Maria's disorganized look fool you. Under that disorganized, deep convection is a closed low-level circulation, with winds of 40-45 mph, and steadily/rapidly falling pressures.


At least...IMO...

Member Since: July 6, 2010 Posts: 113 Comments: 32024
1661. Relix
I believe Maria will make landfall around Ponce, PR.
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Good Riddance Nate. Sorry Mexico it's going your way. We had our share of rain and need or want no more hurricanes anywhere near close to Mississippi.
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Quoting Drakoen:
Buoy to the north of Maria measured a minimum pressure close to 1003mb
Good morning. What are your thoughts on co-ordinates, movement and track ? TIA
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Thanks Guys for posting those maps and MrPr for the "EC."
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Quoting ncstorm:


yeah, I just posted the run..you beat me to it..rides it up the east coast..I guess we will see if this is a beginning a westward trend with the models..
Judging by the 72 hr. SFC Forecast, there is High directly above Maria when she starts to make her Northwest turn.

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1655. Drakoen
Buoy to the north of Maria measured a minimum pressure close to 1003mb
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lee is going to retired too look at the damage he did to new york agnes like
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Quoting ncstorm:


yeah, I just posted the run..you beat me to it..rides it up the east coast..I guess we will see if this is a beginning a westward trend with the models..


Don't know if you got a chance to look at the 5AM discussion on Maria yet, but it sounds like NHC is expecting a westward move as well:

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. GIVEN THE TRACK AND INTENSITY FORECAST...A TROPICAL
STORM WARNING HAS BEEN ISSUED FOR A LARGE PORTION OF THE
NORTHEASTERN CARIBBEAN ISLANDS.
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Steering 700-850 mb. level
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Quoting Chicklit:
Good morning, can someone please post a steering map?
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Quoting caribbeantracker01:
Time: 11:07:00Z
Coordinates: 12.5333N 58.8W
Acft. Static Air Press: 842.8 mb (~ 24.89 inHg)
Acft. Geopotential Hgt: 1,565 meters (~ 5,135 feet)
Extrap. Sfc. Press: 1008.4 mb (~ 29.78 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 301° at 10 knots (From the WNW at ~ 11.5 mph)
Air Temp: 17.7°C (~ 63.9°F)
Dew Pt: 11.2°C (~ 52.2°F)
Peak (10s) Flt. Lvl. Wind: 11 knots (~ 12.6 mph)
SFMR Peak (10s) Sfc. Wind: 19 knots (~ 21.8 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data
Link

No doubt about west winds.
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1649. ncstorm
Quoting GTcooliebai:
NOGAPS too, tries to bring it on a similiar path as Irene Link


yeah, I just posted the run..you beat me to it..rides it up the east coast..I guess we will see if this is a beginning a westward trend with the models..
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1648. ncstorm
06z NOGAPS has landfall on florida with Maria

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Quoting ncstorm:
Good Morning,

I see the 00Z Euro brings Maria into NC

NOGAPS too, tries to bring it on a similiar path as Irene Link
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Quoting Chicklit:
Good morning, can someone please post a steering map?
click on my name i have lots of eye candy for u on my blog
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1645. ncstorm
The 00Z CMC has come west also with Maria

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Good morning, can someone please post a steering map? It appears the 'death ridge' has won out and Nate will take a sharp left into Mexico.
But Maria's fate would seem less certain since the system has gotten so big. Looks like Potts will get his wish after all and get some rain out of it.

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Quoting aislinnpaps:
My classroom and kids are waiting for me. To all the adults, have a fantastic Friday!!
To all those who need attention... This is all you get from me.


don't give 'em to much hw you would be there favorite teacher
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1641. ncstorm
Good Morning,

I see the 00Z Euro brings Maria into NC

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Quoting wxobsvps:


I think somebody is forgetting the upcoming Pattern Change.


Seems like there's always a pattern change coming.

It changes like the weather.

Wait a minute, it is the weather. ;)
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Quoting wxobsvps:
It's official, CONUS landfalling Hurricanes are a thing of science fiction, save for Irene.


then it's not science fiction
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shaping up to be a pretty messing weekend for me expecting heavy flooding here
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Time: 11:07:00Z
Coordinates: 12.5333N 58.8W
Acft. Static Air Press: 842.8 mb (~ 24.89 inHg)
Acft. Geopotential Hgt: 1,565 meters (~ 5,135 feet)
Extrap. Sfc. Press: 1008.4 mb (~ 29.78 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 301° at 10 knots (From the WNW at ~ 11.5 mph)
Air Temp: 17.7°C (~ 63.9°F)
Dew Pt: 11.2°C (~ 52.2°F)
Peak (10s) Flt. Lvl. Wind: 11 knots (~ 12.6 mph)
SFMR Peak (10s) Sfc. Wind: 19 knots (~ 21.8 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data
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My classroom and kids are waiting for me. To all the adults, have a fantastic Friday!!
To all those who need attention... This is all you get from me.
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irene for sure maybe lee retired names
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What is going on with Maria?


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Quoting Gearsts:
Yea but they are not sure about the track yet and are expecting another shift west with the models.
I don't even think they are too sure about the exact co-ordinates either. HH should help a lot.
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Good morning...

Tropical Storm Maria


SFC Analysis


Tropical Wave assoc. w/ Monsoon Trough
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Maria is back moving west. the track will shift left again.
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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.