Hurricane Hunters to check out remains of Fred; 98L more organized

By: Dr. Jeff Masters , 1:06 PM GMT on September 19, 2009

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A tropical disturbance (98L), is located midway between Africa and the Lesser Antilles Islands. This disturbance has shown a modest increase in heavy thunderstorm activity over the past day. This morning's QuikSCAT pass showed an elongated circulation, with top winds around 30 mph. Wind shear is low, 5 - 10 knots, and Sea Surface Temperatures are 28°C, which is about 2°C above the 26°C threshold needed to support a tropical cyclone. There is a large amount of dry air to the north and west of 98L, and this dry air is interfering with development.

Wind shear over 98L is expected to remain in the low range, 5 - 10 knots, through Sunday evening, according to the SHIPS model. This may allow the storm to organize into a tropical depression, assuming it can fight off the dry air that surrounds it. By Monday, the SHIPS model predicts shear will increase to the high range, 15 - 30 knots, so in is unlikely 98L will become anything stronger thatn a weak tropical storm over the coming 5-day period. The models predict that a strong trough of low pressure will turn 98L to the northwest and then north beginning on Monday, with the result that 98L misses the Lesser Antilles Islands by at least 500 miles. NHC is giving 98L a high (greater than 50%) chance of developing into a tropical depression by Monday. At this time, it does not appear that 98L will ever threaten any land areas.

Fred-ex
The remains of Hurricane Fred are still spinning away about 700 miles east of Florida. There has been a modest increase in heavy thunderstorm activity on the south side of Fred's circulation over the past day, but high wind shear and dry air have kept the thunderstorms from building over Fred's center. Wind shear is moderate, 15 - 20 knots, and there is substantial dry air surrounding ex-Fred on all sides. This morning's QuikSCAT pass showed top winds of 30 mph.

None of the computer models develop ex-Fred, and conditions for development are expected to remain marginal over the next three days, with wind shear of 15 - 20 knots and plenty of dry air around. Most of the models predict ex-Fred should move over Florida on Tuesday, but steering currents may weaken early next week, and ex-Fred could end up slowing down and turning northwest towards South Carolina. A hurricane hunter aircraft this afternoon was cancelled.


Figure 1. Morning visible satellite image of 98L and the remains of Hurricane Fred.

Twenty years ago today
On September 19, 1989, Hurricane Hugo moved away from Puerto Rico, and headed northwest at 15 mph. An upper-level low over Georgia, in combination with the steering currents imparted by the Azores-Bermuda High, were responsible for the northwesterly motion of the storm. Wind shear from strong upper-level winds continued to weaken the hurricane, and Hugo diminished to a Category 2 hurricane with 105 mph winds.


Figure 2. GOES visible satellite image of Hurricane Hugo taken on September 19, 1989. Wind shear had weakened Hugo to a Category 2 storm with 105 mph winds. Image credit: Google Earth rendition of the NOAA HURSAT data base.

I'll have an update this afternoon if there's any major developments to report.

Jeff Masters

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Quoting Grothar:


Hey Seastep, fun evening on the blog last night, eh? Does it appear 007L is trying to grasp the moisture from its south, or could that be upper level winds knocking off the convection try to wrap back around?


Yeah, interesting. When something's close and has a defined center, I don't turn my back until it's gone.

I was commenting on that as you were posting. See 507.

Have to see if it continues to increase or not.
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510. JLPR
Quoting Weather456:


it was supporting your post.


JLRP, yeah it had the T# from about 19/0600


yep and it maintained it
I don't get it, why did the NHC downgraded it to orange? :| They should have left it red since quickscat and the T# supports at least a red circle
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting futuremet:


I was talking about the new convective fluxes at 26N. That it self, however, may be caused the frontal boundary.


it was supporting your post.


JLRP, yeah it had the T# from about 19/0600
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Quoting Stormchaser2007:
Ouch...three cheap shots in one TWO.

Wishcatsers must be hurtin.



Let me get this straight, we can no longer have a discussion without someone being called a wishcaster? Not saying people weren't being a little er, well hyped up about ex-Fred. I've been more interested in 98L actually.
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Quoting Stormchaser2007:


Yeah...not a big surprise.

Nothing really to look at. Just a wave interacting with a frontal boundary.






Nice little blowup in the SE quadrant, very close to the center. Thanks for sharing.

We'll see if it persists and increases or not.
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.
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Quoting Seastep:
Looking at updated loop as of 1715, much more activity around the center.



New vortices appearing, yes, but still think center is on the southern edge of that.

Have to see what happens, but Fred isn't going to be naked much longer, imo. We'll see if he can do anything with the added moisture.


Hey Seastep, fun evening on the blog last night, eh? Does it appear 007L is trying to grasp the moisture from its south, or could that be upper level winds knocking off the convection try to wrap back around?
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Quoting Weather456:


The convection we are seeing maybe originating from pre-frontal flow rather than the low itself

Repost

While doing my update this morning, I noticed this frontal boundary and hinted to myself "hey it might do something to Fred" but it does appear it has.




But a great tool to look the flow through the entire atmosphere reveals it maybe having some effect on Fred



I was talking about the new convective fluxes at 26N. That it self, however, may be caused the frontal boundary.
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503. JLPR
ummm???

19/1145 UTC 13.8N 42.2W T2.0/2.0 98L

so? 98L has the T# of a TD
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting futuremet:


Yes, it is trying to increase convection again. How tedious; it'd be best if it degenerate already.



The convection we are seeing maybe originating from pre-frontal flow rather than the low itself

Repost

While doing my update this morning, I noticed this frontal boundary and hinted to myself "hey it might do something to Fred" but it does appear it has.




But a great tool to look the flow through the entire atmosphere reveals it maybe having some effect on Fred

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501. JLPR
Quoting Stormchaser2007:


Yeah...not a big surprise.

Nothing really to look at. Just a wave interacting with a frontal boundary.






its a low interacting with a frontal boundary
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Is it safe to come back on the blog now? Name calling over? I guess the one good thing about being color blind is that red and orange look alike, so one does not get too upset if the color changes. Question: To what ridge are they referreing moving too late over 007L? Would this prevent further strengthening of the system? No need for an expert opinion?
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499. hercj
I have learned one thing about the NHC. When they are truly interested in a feature, they will send up the GIV. No GIV, no interest. I wondered for two days why they didn't put up a flight and now I know. They do not believe this to be a player.
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Quoting Seastep:
Looking at updated loop as of 1715, much more activity around the center.



New vorticities appearing, yes, but still think center is on the southern edge of that.

Have to see what happens, but Fred isn't going to be naked much longer, imo. We'll see if he can do anything with the added moisture.


Yes, it is trying to increase convection again. How tedious; it'd be best if it degenerate already.

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Quoting IKE:


They've just about all left or gone into lurking. I went back and read the posts before recon was canceled. OMG...


Yeah...not a big surprise.

Nothing really to look at. Just a wave interacting with a frontal boundary.




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Fred disgusts me
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Quoting IKE:


They've just about all left or gone into lurking. I went back and read the posts before recon was canceled. OMG...


lol
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As long as it gets swallowed and not spit out...

Can't wait to call this season finished. (I know I have to wait until Dec. 1 to do this officially...)
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Looking at updated loop as of 1715, much more activity around the center.

Quoting futuremet:


Getting sucked in



New vortices appearing, yes, but still think center is on the southern edge of that.

Have to see what happens, but Fred isn't going to be naked much longer, imo. We'll see if he can do anything with the added moisture.
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492. IKE
Quoting Stormchaser2007:
Ouch...three cheap shots in one TWO.

Wishcatsers must be hurtin.


They've just about all left or gone into lurking. I went back and read the posts before recon was canceled. OMG...
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AOI


98L

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Ouch...three cheap shots in one TWO.

Wishcatsers must be hurtin.
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489. JLPR
Quoting CybrTeddy:
If 98L has a good DMAX (no reason it wont) then they'll bump it back to Red.

I have a feeling serious downcasting by trolls (rallying up the blog) is about to occur, So im going to head out again.


yep 98L should get more organized convection tonight, plus with all the convection that has dissipated the environment has become more moist, so expect a healthy 98L tonight
Member Since: September 4, 2007 Posts: 36 Comments: 5223
BurnedAfterPosting,

Ok, I understand.

Also I disagree with the NHC putting it back to orange since the chances they give apply to 48 hrs, not entirely on what's happening now. But I'm not complaining because it does not lead us anywhere. They are the experts. Besides it could easily go back red.
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Quoting Seastep:


Very plausible.


Getting sucked in

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If 98L has a good DMAX (no reason it wont) then they'll bump it back to Red. Thats when everyone will be all 'oh TD by 11 am', then the convection will dissipate again tomorrow, and well all my fellow ole timers know the routine. :)

I have a feeling serious downcasting by trolls (rallying up the blog) is about to occur, So im going to head out again.
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Tick Tock.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
I don't understand why they didn't wait till later to lower it to orange. 98L still has a great structure and all it needs is some more persistent convection then it would be a TD.

I still think 98L will become a TD by tommorow.
Member Since: September 21, 2008 Posts: 9 Comments: 688
I suspect 98L will become the 3rd hurricane of the 2009 season and become the 3rd major hurricane at that, jmo.I've learned something this season about the nhc, they get very frustrated and hate when systems seems to defy the models in regards track and strength, of course this is just my personal observation & opinion.
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Quoting Weather456:


I'm not sure what you mean since the intensity guidance only place it between 40-45 mph.

You mean overdoing as in it would get stronger?


yes, I also think they are overdoing the weakness. To me 98L will only be a weak TS over the next few days, therefore it wont go north

we all know, if this takes longer to develop, it will go further west; if it misses that weakness then its a whole new ballgame
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Quoting futuremet:


If that ridge establishes too late, it might get sucked in.


Very plausible.
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Quoting BurnedAfterPosting:


456, now 98L is back to orange, but the structure is really good

My thoughts are again, consensus is overdoing the strength of 98L and the timing with how long it takes to get strong

This new development to me says 98L will be further south and west again then the consensus shows.


I'm not sure what you mean since the intensity guidance only place it between 40-45 mph.

You mean overdoing as in it would get stronger?
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98L back to orange, I would have thought the nhc would have waited til at least 8 tonight before they lowered it from red, I'm not 2nd guessing the experts but to me even though convection has waned 98L appears more organized in structure to me, jmo though.
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Quoting cchsweatherman:


Definitely not good for you folks in the Caribbean, since if I'm not mistaken, you have been suffering a pretty dramatic rainfall deficit throughout the past year.


yep, due to El Nino and lack of healthy tropical disturbances. The current forecast through November is showing a greater chance of below normal rains than above/near normal.
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477. hercj
Quoting Skyepony:
I was spot on when I suspected AF300 got sent to Caribbean the other day..

Date: Near the closest hour of 16Z on the 19th day of the month
Highest Mandatory Level For Which Wind Was Reported: 400mb
Coordinates: 16.4N 63.1W (View map)
Location: 240 miles (386 km) to the SE (125) from San Juan, Puerto Rico (USA).
Marsden Square: 043 (About)

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1014mb (29.94 inHg) Sea Level (Surface) 28.2C (82.8F) 23.7C (74.7F) Unavailable
1000mb 121m (397 ft) 27.0C (80.6F) 23.4C (74.1F) 80 (from the E) 11 knots (13 mph)
925mb 807m (2,648 ft) 22.4C (72.3F) Approximately 17C (63F) 95 (from the E) 18 knots (21 mph)
850mb 1,539m (5,049 ft) 17.8C (64.0F) 14.6C (58.3F) 95 (from the E) 15 knots (17 mph)
700mb 3,178m (10,427 ft) 11.0C (51.8F) Approximately -14C (7F) 125 (from the SE) 13 knots (15 mph)
500mb 5,890m (19,324 ft) -6.7C (19.9F) Approximately -17C (1F) 175 (from the S) 4 knots (5 mph)
400mb 7,600m (24,934 ft) -10.9C (12.4F) Approximately -32C (-26F) 265 (from the W) 13 knots (15 mph)

How about that shear:)
Where did you get this? I got it. Its in the training mission data.
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Quoting Weather456:
98L is large

reminds me of Bill 09'.
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Quoting Weather456:
98L is large



456, now 98L is back to orange, but the structure is really good

My thoughts are again, consensus is overdoing the strength of 98L and the timing with how long it takes to get strong

This new development to me says 98L will be further south and west again then the consensus shows.
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Quoting Weather456:


part of my winter outlook. Drought relief coming to SE Texas. And most likely wetter conditions for the Southern USA. While below normal rainfall for parts of the Caribbean.


Definitely not good for you folks in the Caribbean, since if I'm not mistaken, you have been suffering a pretty dramatic rainfall deficit throughout the past year.
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455. - It would be neat. I remember in 1977 when snow fell, even though I was 4 1/2.

Was 1976 - 1977 an El Nino year? After reading about it, it was caused by two Artic Fronts dipping low.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Quoting Seastep:
Fred's COC is still at around 26N/70W based on sat.

The interaction is creating convection to the N.

From what I see, it is not being absorbed. It is new convection. Absorbed would imply that the convection fired over Fred and was being pulled N. Quite the opposite is what I see. Convection firing to the N and moving S, towards Fred's coc. Which makes sense based on shear direction.

I think it will help Fred, actually. Introduces more moisture.

Judge for yourself. RAMSDIS Flash floater



If that ridge establishes too late, it might get sucked in.
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471. IKE
So much for the red circle.
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98L is large

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469. JRRP
out!
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468. IKE
A trifecta....


TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SAT SEP 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A SURFACE TROUGH ASSOCIATED WITH THE REMNANTS OF FRED IS LOCATED
ABOUT 475 MILES EAST-NORTHEAST OF THE NORTHWESTERN BAHAMAS AND IS
PRODUCING DISORGANIZED SHOWERS AND THUNDERSTORMS. THIS SYSTEM HAS
BECOME LESS ORGANIZED DURING THE DAY
AND THE RECONNAISSANCE MISSION
SCHEDULED FOR THIS AFTERNOON HAS BEEN CANCELED. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES SLOWLY TOWARD THE
WEST-NORTHWEST.

SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED IN ASSOCIATION WITH
A BROAD AREA OF LOW PRESSURE CENTERED ABOUT 1200 MILES EAST OF THE
WINDWARD ISLANDS.
HOWEVER...THIS SYSTEM STILL HAS THE POTENTIAL TO
BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR TWO AS IT MOVES
TOWARD THE WEST-NORTHWEST AT AROUND 10 MPH. THERE IS A MEDIUM
CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

AN AREA OF DISTURBED WEATHER LOCATED A COUPLE HUNDRED MILES
NORTHEAST OF THE CAPE VERDE ISLANDS HAS BECOME LESS ORGANIZED OVER
THE PAST SEVERAL HOURS.
DEVELOPMENT OF THIS SYSTEM IS NOT
ANTICIPATED AS IT MOVES TOWARD THE WEST-NORTHWEST AT ABOUT 10 MPH.
THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BLAKE
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Quoting hurricane23:


Pretty typical with el nino years as the storm track is futher southward.


part of my winter outlook. Drought relief coming to SE Texas. And most likely wetter conditions for the Southern USA. While below normal rainfall for parts of the Caribbean.
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Fred's COC is still at around 26N/70W based on sat.

The interaction is creating convection to the N.

From what I see, it is not being absorbed. It is new convection. Absorbed would imply that the convection fired over Fred and was being pulled N. Quite the opposite is what I see. Convection firing to the N and moving S, towards Fred's coc. Which makes sense based on shear direction.

I think it will help Fred, actually. Introduces more moisture.

Judge for yourself. RAMSDIS Flash floater

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Quoting Weather456:
Track guidance did not verified over the past 24 hrs



Yep too many variables
Member Since: September 19, 2005 Posts: 2 Comments: 4111
Quoting futuremet:
Messy...



Agreed. It appears to have become part of the pre-frontal flow now as the circulation and associated convection has become elongated in response to the frontal boundary crossing very near to the north.
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000
ABNT20 KNHC 191732
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SAT SEP 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A SURFACE TROUGH ASSOCIATED WITH THE REMNANTS OF FRED IS LOCATED
ABOUT 475 MILES EAST-NORTHEAST OF THE NORTHWESTERN BAHAMAS AND IS
PRODUCING DISORGANIZED SHOWERS AND THUNDERSTORMS. THIS SYSTEM HAS
BECOME LESS ORGANIZED DURING THE DAY AND THE RECONNAISSANCE MISSION
SCHEDULED FOR THIS AFTERNOON HAS BEEN CANCELED. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES SLOWLY TOWARD THE
WEST-NORTHWEST.

SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED IN ASSOCIATION WITH
A BROAD AREA OF LOW PRESSURE CENTERED ABOUT 1200 MILES EAST OF THE
WINDWARD ISLANDS. HOWEVER...THIS SYSTEM STILL HAS THE POTENTIAL TO
BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR TWO AS IT MOVES
TOWARD THE WEST-NORTHWEST AT AROUND 10 MPH. THERE IS A MEDIUM
CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

AN AREA OF DISTURBED WEATHER LOCATED A COUPLE HUNDRED MILES
NORTHEAST OF THE CAPE VERDE ISLANDS HAS BECOME LESS ORGANIZED OVER
THE PAST SEVERAL HOURS. DEVELOPMENT OF THIS SYSTEM IS NOT
ANTICIPATED AS IT MOVES TOWARD THE WEST-NORTHWEST AT ABOUT 10 MPH.
THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BLAKE
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462. Skyepony (Mod)
I was spot on when I suspected AF300 got sent to Caribbean the other day..

Date: Near the closest hour of 16Z on the 19th day of the month
Highest Mandatory Level For Which Wind Was Reported: 400mb
Coordinates: 16.4N 63.1W (View map)
Location: 240 miles (386 km) to the SE (125°) from San Juan, Puerto Rico (USA).
Marsden Square: 043 (About)

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1014mb (29.94 inHg) Sea Level (Surface) 28.2°C (82.8°F) 23.7°C (74.7°F) Unavailable
1000mb 121m (397 ft) 27.0°C (80.6°F) 23.4°C (74.1°F) 80° (from the E) 11 knots (13 mph)
925mb 807m (2,648 ft) 22.4°C (72.3°F) Approximately 17°C (63°F) 95° (from the E) 18 knots (21 mph)
850mb 1,539m (5,049 ft) 17.8°C (64.0°F) 14.6°C (58.3°F) 95° (from the E) 15 knots (17 mph)
700mb 3,178m (10,427 ft) 11.0°C (51.8°F) Approximately -14°C (7°F) 125° (from the SE) 13 knots (15 mph)
500mb 5,890m (19,324 ft) -6.7°C (19.9°F) Approximately -17°C (1°F) 175° (from the S) 4 knots (5 mph)
400mb 7,600m (24,934 ft) -10.9°C (12.4°F) Approximately -32°C (-26°F) 265° (from the W) 13 knots (15 mph)

How about that shear:)
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461. JRRP
Quoting Relix:
98L looks HUUUUUGE on the Satellite link poste by JRRP. Looks like one of those major CV hurricanes in formation =P . Thankfully it seems it will go north of us here in the islands and to the sea.

not as fast...
:D
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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.