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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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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Quoting Vincent4989:

So is Nate is the smallest cyclone in terms of convection?
Storm sizes are usually determined by gale width, if I'm not mistaken.
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1574. 3211976
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Best looking storm of 2011 thus far.

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Quoting MoltenIce:
Convection redeveloping?

As for size, Nate's circulation is still larger than Marco's but since Nate's convection fizzled briefly...it may give an appearance that might imply it is smaller than Marco.

So is Nate is the smallest cyclone in terms of convection?
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Convection redeveloping?

As for size, Nate's circulation is still larger than Marco's but since Nate's convection fizzled briefly...it may give an appearance that might imply it is smaller than Marco.
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Marco:

Nate:

Which one is smaller?
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Buoy 41101 down to 1003.4

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Quoting spinningtop:
its funny how they always say these storms will hit florida when they are 6 days out but then by 4 days they change it to the big hook out to sea thats why we never worry about them in florida they always make the hook


All for positive here...but thats a incorrect statement. Floridas day is coming. Just a matter of time.
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1566. 3211976
I thin those new coordinates are too north
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Quoting HurrikanEB:
HURRICANE KATIA DISCUSSION NUMBER 45
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 AM AST FRI SEP 09 2011

THE CLOUD PATTERN CONTINUES WELL ORGANIZED AND IN FACT A DRIFTING
BUOY NEAR THE CENTER OF THE HURRICANE RECENTLY REPORTED A MINIMUM
PRESSURE OF 968 MB. THE INITIAL INTENSITY IS KEPT AT 75 KNOTS.
HOWEVER WEAKENING IS INDICATED SINCE THE HURRICANE IS ALREADY
REACHING COOLER WATERS AND KATIA IS FORECAST TO BECOME
POST-TROPICAL IN ABOUT 36 HOURS.

THE HURICANE IS MOVING TOWARD THE NORTHEAST OR 050 DEGREES AT 21
KNOTS. SINCE THE HURRICANE IS ALREADY EMBEDDED WITHIN THE
MID-LATITUDE WESTERLIES....IT SHOULD CONTINUE ON THIS GENERAL TRACK
WITH AN INCREASE IN FORWARD SPEED FOR THE NEXT FEW DAYS.

NO 96-HOUR POINT IS BEING GIVEN BECAUSE FORECAST POINTS IN THE
EASTERN HEMISPHERE BREAK A LOT OF SOFTWARE.



hahaha... I've never seen something like that in a discussion.


Sounds like someone got frustrated
maybe they ought to think about a software upgrade
Member Since: August 23, 2008 Posts: 0 Comments: 1918
Quoting spinningtop:
the florida force field holds strong again as maria takes the big hook


Looks like it anyway. Hope it holds
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Quoting Gearsts:
Maria is also slowing down.


Maybe gonna make the turn as suggested by HWRF and GFDL, both of which barely clip the islands. Would be nice.
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1560. Gearsts
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Quoting gugi182:
EMILY, IRENE now MARIA well i just figured these ladies are abusing my little island.


I cant help but notice that it seems that the "female" storms more often tend to come in pairs, as far as location of impact goes. Off the top of my head.... 2004: Frances & Jeanne. 2005: Rita, Wilma, and Katrina practically all passed over the same intersection near florida. Aside from Dean/Felix I cant really recall any "guy" groupings.
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Quoting FrankZapper:
Big blackout in southern California. 2 million with no power.


went out at about 4pm pst,mine came back on at 12:15am,over 4million affected, mostly entire san diego county,part of orange county,parts of arizona,new mexico,mexico,heard they had a major line under/over volting and personel in arizona did the wrong thing,utility company lost both lines,san onofre nuclear had to shut down its 2 reactors,probably 50-75% restored at this time.
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HURRICANE KATIA DISCUSSION NUMBER 45
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 AM AST FRI SEP 09 2011

THE CLOUD PATTERN CONTINUES WELL ORGANIZED AND IN FACT A DRIFTING
BUOY NEAR THE CENTER OF THE HURRICANE RECENTLY REPORTED A MINIMUM
PRESSURE OF 968 MB. THE INITIAL INTENSITY IS KEPT AT 75 KNOTS.
HOWEVER WEAKENING IS INDICATED SINCE THE HURRICANE IS ALREADY
REACHING COOLER WATERS AND KATIA IS FORECAST TO BECOME
POST-TROPICAL IN ABOUT 36 HOURS.

THE HURICANE IS MOVING TOWARD THE NORTHEAST OR 050 DEGREES AT 21
KNOTS. SINCE THE HURRICANE IS ALREADY EMBEDDED WITHIN THE
MID-LATITUDE WESTERLIES....IT SHOULD CONTINUE ON THIS GENERAL TRACK
WITH AN INCREASE IN FORWARD SPEED FOR THE NEXT FEW DAYS.

NO 96-HOUR POINT IS BEING GIVEN BECAUSE FORECAST POINTS IN THE
EASTERN HEMISPHERE BREAK A LOT OF SOFTWARE.



hahaha... I've never seen something like that in a discussion.
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1556. Gearsts
Maria is also slowing down.
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Wow NWS might need to update their stuff as per last post

this is from the NHC this morning

4:00 AM CDT Fri Sep 9
Location: 19.9°N 92.3°W
Max sustained: 65 mph
Moving: Stationary
Min pressure: 998 mb
Member Since: August 23, 2008 Posts: 0 Comments: 1918
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1553. SLU
The NHC places it in the middle of the 2 ... at least until the RECON gets there in a couple hours.
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1552. SLU
5:00 AM AST Fri Sep 9
Location: 13.8°N 56.2°W
Max sustained: 40 mph
Moving: WNW at 18 mph
Min pressure: 1003 mb
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1551. SLU
The old LLC appears to be near 13.5n 57.5w
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1550. SLU
Quoting JLPR2:


With those observation and buoy being at 14.6N and Maria at Approx. 13.6N I believe its barometric pressure must be around 1003-1002mb. Winds doesn't seem to be responding to the drop yet.

Also, seems like a reformation of the LLC took place, we are now following a new LLC with the old one accelerating westward towards Barbados.


You are right. That new center could be near 14.5n 55.5w ... give and take a few degrees on either side.
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1549. JLPR2
Quoting Gearsts:
OMG what the Fux is happening? HH plain we need you inside her.


With those observation and buoy being at 14.6N and Maria at Approx. 13.6N I believe its barometric pressure must be around 1003-1002mb. Winds doesn't seem to be responding to the drop yet.

Also, seems like a reformation of the LLC took place, we are now following a new LLC with the old one accelerating westward towards Barbados.
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1548. Gearsts
Quoting JLPR2:
Buoy
14.600 N 56.201 W (14.36'0" N 56.12'2" W)
Wind Direction (WDIR): ENE ( 60 deg true )
Wind Speed (WSPD): 25.1 kts
Wave Height (WVHT): 16.7 ft
Dominant Wave Period (DPD): 11 sec
Atmospheric Pressure (PRES): 29.64 in (1003.7mb)
Pressure Tendency (PTDY): -0.08 in ( Falling )
Air Temperature (ATMP): 79.0 °F
Water Temperature (WTMP): 83.7 °F
Dew Point (DEWP): 77.7 °F
Heat Index (HEAT): 83.5 °F

OMG what the Fux is happening? HH plain we need you inside her.
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1547. JLPR2
Buoy
14.600 N 56.201 W (14.36'0" N 56.12'2" W)
Wind Direction (WDIR): ENE ( 60 deg true )
Wind Speed (WSPD): 25.1 kts
Wave Height (WVHT): 16.7 ft
Dominant Wave Period (DPD): 11 sec
Atmospheric Pressure (PRES): 29.64 in (1003.7mb)
Pressure Tendency (PTDY): -0.08 in ( Falling )
Air Temperature (ATMP): 79.0 °F
Water Temperature (WTMP): 83.7 °F
Dew Point (DEWP): 77.7 °F
Heat Index (HEAT): 83.5 °F

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maria is getting big!!!!!!!!!
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1545. JLPR2
Nuts! The center is under the heaviest convection.

I hope Maria isn't doing hidden RI.
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1544. Gearsts
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31.4n70.2w, 32.9n70.2w, 33.9n70.1w, 35.6n69.4w have been re-evaluated&altered for H.Katia's_6amGMT_ATCF
31.4n70.1w, 32.9n70.2w, 33.9n70.1w, 35.6n69.4w, 36.9n68.5w are now the most recent positions
Starting 8Sept_6amGMT and ending 9Sept_6amGMT

The 4 southern line-segments represent HurricaneKatia's path,
the northernmost line-segment is the straightline projection,
and the coastline dumbbell at YQI-43.481n65.656w is the endpoint of the
most recent
previous straightline projection connected to its nearest airport.

Using straightline projection of the travel-speed&heading derived from the
ATCF coordinates spanning the 6hours between 12amGMT then 6amGMT :
H.Katia's travel-speed was 17.2mph(27.6k/h) on a heading of 29degrees(NNE)
H.Katia was headed toward passage over WineHarbour,NovaScotia ~1day1hour from now

Copy&paste 43.481n65.656w-yqi, 31.4n70.1w-32.9n70.2w, 32.9n70.2w-33.9n70.1w, 33.9n70.1w-35.6n69.4w, 35.6n69.4w-36.9n68.5w, yps, 35.6n69.4w-45.071n61.833w into the GreatCircleMapper for more info

The previous mapping (for 9Sept_12amGMT)
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Marie has some crazy convection going on and she's still riping west..... think the models will shift more west. All the models look to nw to me
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That's Katia's remnants, a 968mb low or so. Mets here have been unusually mentioning this system well in advance over the last two days. Rare they bother doing that.

NHC seem to want to keep it at around 65mph sustained or so, meaning gusts higher than that. UKMET is only talking about 'risk of severe gales' which is around Force 9, lower than 65mph. The way it is worded seems to imply it won't be as strong or most of the stronger winds remain offshore.

Remains to be seen what occurs and how strong it is. Jet stream is still strong in the path and it is interacting with another low.
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1540. JLPR2
Quoting Gearsts:
The magic of 55W


XD
Yeah, the sweet spot.
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1539. Gearsts
Quoting JLPR2:


I'm wondering what caused this explosion of convection too, we are supposed to be in a negative MJO. O.o

Maybe it is slowing down and found nicer and deeper hot waters.
The magic of 55W
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1538. JLPR2
Quoting farupnorth:
When is recon going to Maria?


They are supposed to take off at: 09/0930Z.

A little less than two hours.
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1537. JLPR2
Quoting farupnorth:


Maybe it met the Convectively-Coupled Kelvin Wave doc was talking about heading east?

No idea or just shear relaxed


I'm wondering what caused this explosion of convection too, we are supposed to be in a negative MJO. O.o

Maybe it is slowing down and found nicer and deeper hot waters.
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When is recon going to Maria?
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Quoting JLPR2:
Nate's convection is really shallow.


Compare it to Maria's.


Maybe it met the Convectively-Coupled Kelvin Wave doc was talking about heading east?

No idea or just shear relaxed
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1534. JLPR2
That band of intense convection is basically on top of the circulation now, I wonder if it will wrap around it.

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1533. 3211976
Wow 1004mb
Quoting Gearsts:
Today will be and interesting day

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Quoting LavosPhoenix:


Yes, it is the remnants of Lee and it is pretty unusual for us to get rain from that direction and I agree, we do need the rain.


No, it's not Lee, it's an upper level low pressure system.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
156 AM CDT FRI SEP 9 2011

DISCUSSION

/156 AM CDT FRI SEP 9 2011/

NO SIGNIFICANT CHANGES PLANNED FOR GOING FORECAST. MODELS ARE
SIMILAR IN SLOWLY RETROGRADING THE 500MB LOW CURRENTLY ALONG THE
IL/IN INTO THE CWA TONIGHT. THE LOW WILL EVENTUALLY OPEN UP AND
LIFT OUT ON SUNDAY ALLOWING A LOW AMPLITUDE RIDGE TO MOVE IN
BEHIND IT FOR EARLY NEXT WEEK.
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1531. JLPR2
Quoting Gearsts:
Today will be and interesting day


Today will be a day full of WTF's. XD
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1530. Gearsts
Quoting JLPR2:
Buoy
14.600 N 56.201 W (14.36'0" N 56.12'2" W)

Wind Direction (WDIR): NE ( 40 deg true )
Wind Speed (WSPD): 26.0 kts
Wave Height (WVHT): 15.4 ft
Dominant Wave Period (DPD): 10 sec
Atmospheric Pressure (PRES): 29.66 in
Pressure Tendency (PTDY): -0.09 in ( Falling Rapidly )
Air Temperature (ATMP): 81.3 °F
Water Temperature (WTMP): 83.7 °F
Dew Point (DEWP): 77.5 °F
Heat Index (HEAT): 89.1 °F

1004mb... WTF!

Today will be and interesting day
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1529. JLPR2
925mb vort

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1528. JLPR2
Buoy
14.600 N 56.201 W (14.36'0" N 56.12'2" W)

Wind Direction (WDIR): NE ( 40 deg true )
Wind Speed (WSPD): 26.0 kts
Wave Height (WVHT): 15.4 ft
Dominant Wave Period (DPD): 10 sec
Atmospheric Pressure (PRES): 29.66 in
Pressure Tendency (PTDY): -0.09 in ( Falling Rapidly )
Air Temperature (ATMP): 81.3 °F
Water Temperature (WTMP): 83.7 °F
Dew Point (DEWP): 77.5 °F
Heat Index (HEAT): 89.1 °F

1004mb... WTF!

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1527. 3211976