Disturbance 91L spins towards Cape Hatteras; Cyclone Aila toll at 180

By: Dr. Jeff Masters , 1:28 PM GMT on May 27, 2009

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An area of disturbed weather, dubbed "91L" by the National Hurricane Center, is centered 120 miles south of Cape Hatteras, North Carolina. While the storm does not have much in the way of heavy thunderstorm activity, it does have a well-developed circulation, and the spin of the system is readily apparent on long range radar animations out of Morehead City, North Carolina. The disturbance is over waters of 25 - 26°C and has wind shear of 10 - 15 knots over it, and these conditions are marginally favorable for some slow development to occur until Thursday afternoon, when the system will begin moving over waters too cold to support tropical cyclone development. The disturbance will track north or north-northeastward at 10 - 15 mph towards North Carolina's Outer Banks today, then get swept northeastwards out to sea on Thursday. It is unlikely that the disturbance has enough time to develop into a tropical depression, but an Air Force hurricane hunter flight is on call to investigate the system this afternoon, if necessary. If the system does develop, the current location of the heaviest thunderstorm activity in a band well removed from the center suggests that 91L would be classified as a subtropical depression. The Outer Banks of North Carolina can expect 20 - 25 mph winds and heavy rain from this system tonight and Thursday morning. In a Special Tropical Weather Outlook issued at 8am EDT this morning, NHC gave 91L a low (less than 30% chance) of developing into a tropical depression.


Figure 1. Latest radar image from the Morehead City, NC radar.

Tropical Cyclone Aila death toll at 180
The year's deadliest tropical cyclone so far, Tropical Cyclone Aila, has killed at least 180 people in India and Bangladesh border region, according to the latest media reports. Aila hit the India/Bangladesh border region on May 25 as a borderline tropical storm/Category 1 hurricane, bringing sustained winds of 65 - 75 mph and a 3 - 4 meter (10 - 13 foot) storm surge to the coast. Aila has left over 150,000 homeless in India and 500,000 in Bangladesh. The cyclone destroyed over 180,000 homes in Bangladesh--a severe blow for a region still recovering from the devastation wrought by Category 4 Tropical Cyclone Sidr of November 2007, which killed 3,500 people. The death toll form Aila will likely go much higher, as over 500 people are still missing. The Bay of Bengal is no stranger to deadly cyclones--fifteen of the world's twenty deadliest tropical cyclones have been Bay of Bengal storms that have hit Bangladesh, India, or Myanmar. The most recent was last year's Cyclone Nargis, which killed 146,000 people in Myanmar.


Figure 2. Satellite image of Aila as it made landfall near the India/Bangladesh border. Image credit: NASA.

Interview tonight on hurricanetrack.com
I'll be doing one of my periodic spiels on Internet radio tonight at 9pm EDT. Tune your browsers to www.hurricanetrack.com and listen in to my interview with host Mark Sudduth. There is also a live chat to participate in. Hurricane season starts Monday!

Jeff Masters

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BBL,

Tropical Update
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting weathermanwannabe:


Thanks...I figured it might have something to do with "convergence" or "divergence" of some kind (nothing to get excited about)....Lol; I'm not quite there yet on my knowledge of these two terms!


Lol I know I've had to use that explanation for at least 4 blobs now in the last week. Those two terms really aren't that complicated.

Divergence basically is "spreading out of air"

Convergence basically is "piling up of air"

See? Pretty simple lol. For most of these blobs I'm talking about upper-level divergence. You can translate that into "spreading out of air in the upper levels". When you think about that, if air is spreading out up there, then new air needs to come in to replace it. The only place it can come from is below, so air at the lower levels rises up to replace the air spreading out at the top. And we all know that when air rises it condenses into clouds and if strong enough, thunderstorms, such as the ones over SE Texas right now.

BTW "diffluence" is another term used synonymously with "divergence", and similarly "confluence" and "convergence" basically mean the same thing.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Levi - sorry was playing farmtown.. ugh I know. The actual radarcast. I like the storm tracks one too!
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Quoting Levi32:


No, it's just another area of upper divergence causing an area of thunderstorms. Shear is actually quite high in the GOM right now. The only area of light shear is confined to the NE gulf coast.


Thanks...I figured it might have something to do with "convergence" or "divergence" of some kind (nothing to get excited about)....Lol; I'm not quite there yet on my knowledge of these two terms!
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Quoting weathermanwannabe:


Are they possibly referrng to that area of covection, at the tail end of the frontal remnant, sweeping off of Texas right now into the NW Gulf?.........Sheer is pretty low in the Northern Gulf right now as we saw this weekend with the best orgnaization of the low just before reaching the coast.


No, it's just another area of upper divergence causing an area of thunderstorms in advance of the front. Shear is actually quite high in the GOM right now. The only area of light shear is confined to the NE gulf coast and will disappear by tomorrow. The surface trough talked about in the NWS discussion will be under 30-50 knots of shear so any chance of a formation of a tropical disturbance is minimal.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
I don't know much about how the satellite senses temperature, but I imagine the shallow reefs in that area have something to do with it. I'm sure the water could reach 100 degrees considering it's only about 10 ft deep and the coral is dark colored
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Quoting windsurfer68:
The one on this website. Go to the top of this page and click "Tropical/Hurricane" and then click "North Atlantic." The temperatures are always extreme compared to other places.


Probably incomplete data...shallow waters.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
GOM IR Loop..
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The one on this website. Go to the top of this page and click "Tropical/Hurricane" and then click "North Atlantic." The temperatures are always extreme compared to other places.
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Quoting HobeSoundShudders:
and here's what they say about "stuff" in Gulf, the afternoon disc. should be out soon

MARINE WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
320 AM EDT WED MAY 27 2009

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA
AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W.

GULF OF MEXICO...
A SHARP UPPER TROUGH IS MOVING ACROSS THE NE GULF THIS
MORNING...ENHANCING A SMALL BUT VIGOROUS CLUSTER OF
THUNDERSTORMS OVER THE SE GULF WATERS. OTHERWISE GENERALLY LIGHT
TO MODERATE SE TO S WINDS PREVAIL AROUND A WEAK SURFACE RIDGE
EXTENDING FROM THE FLORIDA BIG BEND AREA THROUGH THE TEXAS
COAST. A 00Z SCATTEROMETER PASS SHOWED THE NOTABLE EXCEPTION OF
20 KT FLOW ALONG THE WEST COAST OF THE YUCATAN PENINSULA...DUE
TO LOCAL DIURNAL INFLUENCES. ALTHOUGH IT IS NOT APPARENT FROM
SATELLITE OR OBSERVATIONS OVERNIGHT...THERE HAVE BEEN REPORTS OF
THICK SMOKE OVER THE BAY OF CAMPECHE DUE TO WILDFIRES OVER
SOUTHERN MEXICO. MEANWHILE A SHORT WAVE TROUGH OVER THE CENTRAL
PLAINS IS PUSHING WEAK SURFACE FRONT INTO TEXAS. THE FRONT IS
EXPECTED TO MOVE INTO THE FAR NW GULF BY WED NIGHT...THEN REACH
FROM THE MISSISSIPPI DELTA TO SOUTHERN TEXAS BY THU NIGHT. THE
00Z GFS RUN MAINTAINS A SMALL LOW PRES AREA FORMING ALONG THE
FRONT OVER THE EASTERN GULF BY LATE THU. THE ECMWF AND UKMET
SHOW ONLY MODEST TROUGHING OVER THE SW GULF THROUGH THE SAME
PERIOD. THE FAIRLY STRONG SOUTHERN STREAM JET NOSING INTO THE
AREA SOUTH OF THE SHORT WAVE TROUGH SHOWING UP IN ALL THE MODELS
LENDS CREDENCE TO SOME SURFACE TROUGH FORMING THROUGH 48
HOURS...ALTHOUGH PERHAPS NOT STRONG AS THE GFS IS DEPICTED.
WILL
INTRODUCE 15 TO 20 KT FLOW INTO THE EASTERN GULF AHEAD OF THE
FRONT THU...BUT OTHERWISE NO MAJOR CHANGES ANTICIPATED TO THE
MARINE FORECAST.


Are they possibly referrng to that area of covection, at the tail end of the frontal remnant, sweeping off of Texas right now into the NW Gulf?.........Sheer is pretty low in the Northern Gulf right now as we saw this weekend with the best orgnaization of the low just before reaching the coast.
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85. IKE
...
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Weather456:
Recoon still on?


No its canceled.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting windsurfer68:
Looking at the SSTs off the Guatemala coast on the water temperature map, why is the water temperature always in the "Black" (100 degrees)?


Do you have a link to the map you are looking at??
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Looking at the SSTs off the Guatemala coast on the water temperature map, why is the water temperature always in the "Black" (100 degrees)?
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Recoon still on?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Levi32:


Well you need Google Earth....shouldn't have to have the latest version though.


Thanks
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Seeing that it is unlikely that 91L will form, its back to blob watching.

Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting wxhatt:


Will I have to load the Google Earth 5.0 program to view the data/ maps?


Well you need Google Earth....shouldn't have to have the latest version though.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting Levi32:
Oh here's the one most people have been using.


Will I have to load the Google Earth 5.0 program to view the data/ maps?
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91L looks better than yesterday and very subtropical like
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NexSat Se Overview,91L
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Quoting Orcasystems:


Sorry its one of my pet peeves on here.. There are some on here who think if it does not hit CONUS, then its just a fish storm.


No need to apologize, I know it can be frustrating.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting Levi32:


Exactly. 180 people died from a tropical cyclone, and just because it was half a world away doesn't mean it was any less traumatic for the people of India and Bangladesh.


Sorry its one of my pet peeves on here.. There are some on here who think if it does not hit CONUS, then its just a fish storm.
Member Since: October 1, 2007 Posts: 81 Comments: 26516
Quoting Orcasystems:


Disturbance 91L spins towards Cape Hatteras; Cyclone Aila toll at 180

I will leave it at that.. I won't compare the numbers to what Americans call a devestating Hurricane that hits the USA.


Exactly. 180 people died from a tropical cyclone, and just because it was half a world away doesn't mean it was any less traumatic for the people of India and Bangladesh. Our prayers go out to them.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting cycloone:
It%u2019s been quite around the globe and the hasn't been a single extremely devastating cyclone (Thankfully) to make the news and get people thinking about storm preparedness.


Disturbance 91L spins towards Cape Hatteras; Cyclone Aila toll at 180

I will leave it at that.. I won't compare the numbers to what (some) Americans call a devestating Hurricane that hits the USA.
Member Since: October 1, 2007 Posts: 81 Comments: 26516
National Hurricane Center Forecast Verification
Updated 21 May 2008



Contents

1. Introduction
2. Forecast verification procedures
3. Annual NHC verification reports
4. Official five-year mean errors and distributions
5. Official error trends
6. Model error trends
7. NHC official forecast error database
8. Performance measures and goals
9. References

1. Introduction

NHC receives frequent inquiries on the accuracy and skill of its forecasts and of the computer models available to it. To help answer these questions, these verification web pages were established in March 2005. The development of this resource will be completed in stages; ultimately all available records dating back to the earliest NHC forecasts in 1954 will be included. A digital database of NHC official track forecast errors has been constructed for the period 1970 to the present, and it is this period that is presented initially here. A digital database of intensity errors has been constructed dating back to 1990. These pages will be updated as extensions to the database are completed. Questions on NHC forecast verifications may be directed to James.Franklin@noaa.gov.

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Oh here's the one most people have been using.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting eye2theskies:


I presume that we'll be able to track this via Google Earth like last year? Does anyone have that link?


I believe it's this one, but there are a couple other ones out there that I lost the links to when I switched computers, I'll keep looking.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting Levi32:


It will be in there by 4:30 eastern time.


I presume that we'll be able to track this via Google Earth like last year? Does anyone have that link?
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Quoting system645:
has the recon gone in? If not what time will it go in?


It is scheduled to be in there by 4:30 eastern time.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Plan of the Day

000
NOUS42 KNHC 261630
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1230 PM EDT TUE 26 MAY 2009
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 27/1100Z TO 28/1100Z MAY 2009
WSPOD NUMBER.....09-002

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (OFF CAROLINA COAST)
FLIGHT ONE -- TEAL 70
A. 27/2100Z
B. AFXXX 01AAA INVEST
C. 27/1730Z
D. 34.0N 74.5W
E. 27/2030Z TO 28/0030Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 71
A. 28/0600Z
B. AFXXX 0201A CYCLONE
C. 28/0145Z
D. 35.5N 73.0W
E. 28/0500Z TO 28/0830Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: POSSIBLE FIX NEAR 37N 71W
AT 28/1800Z.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
JWP

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has the recon gone in? If not what time will it go in?
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NASA High-Resolution Visible Loop of Invest 91L moving by the NC outer banks
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Great satellite image of the Bay of Bengal storm
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Now back to H-Season; here is a good list of supplies for the season today from the Florida Governor:

Some of the items included on the emergency supply list include:
· Water
· Food - at least enough for 3 to 7 days
o Non-perishable packaged or canned food / juices
o Snack foods
o Non-electric can opener
o Cooking tools / fuel
o Paper plates / plastic utensils
· Flashlights and portable, self-powered light sources
· Portable radios, two-way radios and NOAA weather-band radios
· Flexible waterproof sheeting (tarps)
· Gas or diesel fuel containers
· Batteries
· Medications
· Ice chests or other food storage coolers
· Portable generators
· Carbon monoxide detectors
· Storm shutter devices
· Pet carrier and supplies

Governor Crist also emphasized the importance of maintaining a supply of necessary prescription drugs along with special food for infants or elders. He encouraged Floridians to document all valuables and to consolidate important personal documents including, bank account numbers, Social Security cards and immunization records in a waterproof container.
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ReliefWEB


Tropical Cyclone Aila - May 2009
Updates on India, Bangladesh affected by the Tropical Cyclone Aila - May 2009 emergency. GLIDE No. TC-2009-000105-BGD


Latest Updates


27 May 2009

OCHA

Statement on Cyclone Aila by John Holmes, United Nations Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator
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Weds Lesson from the National Hurricane Prep Week

Inland Flooding

"In the 1970s, '80s, and '90s, inland flooding was responsible for more than half of the deaths associated with tropical cyclones in the United States."

Inland Flooding
"In the 1970s, '80s, and '90s, inland flooding was responsible for more than half of the deaths associated with tropical cyclones in the United States."
Ed Rappaport
National Hurricane Center

When it comes to hurricanes, wind speeds do not tell the whole story. Hurricanes produce storm surges, tornadoes, and often the most deadly of all - inland flooding.

While storm surge is always a potential threat, more people have died from inland flooding from 1970 up to 2000. Intense rainfall is not directly related to the wind speed of tropical cyclones. In fact, some of the greatest rainfall amounts occur from weaker storms that drift slowly or stall over an area.

Inland flooding can be a major threat to communities hundreds of miles from the coast as intense rain falls from these huge tropical air masses.

Tropical Storm Allison (2001) produced extremely heavy rainfall and catastrophic floods in the Houston, Texas area. Allison then acquired subtropical characteristics and continued to produce heavy rainfall and flooding near its track from Louisiana eastward to North Carolina, and then northward along the U.S. east coast to Massachusetts. Forty-one deaths were directly related to the heavy rain, flooding, tornadoes, and high surf. Damage estimates reported by the Federal Emergency Management Agency (FEMA) were near $5 billion, with approximately $4.8 billion in the Houston metropolitan area alone
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Quoting txalwaysprepared:


How so?
It’s been quite around the globe and the hasn't been a single extremely devastating cyclone (Thankfully) to make the news and get people thinking about storm preparedness.
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Quoting txalwaysprepared:
Hi all! Hope everyone had a great weekend.

Question: Is there a site that show a "futurecast?" Where the computers think thunderstorms and such will head? I used to have access to it when I worked in TV, but don't anymore.

TIA!


You talking about storm tracks like this? Or actual "radarcast" predictions of what the radar map will look like.

Member Since: November 24, 2005 Posts: 635 Comments: 26700
THANKS!!
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Where is STORMTOP these days?
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Quoting cycloone:
I beleive this 2009 Hurricane Season may take some people by suprise


How so?
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Hi all! Hope everyone had a great weekend.

Question: Is there a site that show a "futurecast?" Where the computers think thunderstorms and such will head? I used to have access to it when I worked in TV, but don't anymore.

TIA!
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I beleive this 2009 Hurricane Season may take some people by suprise
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Extra-Tropical storm on tap for Friday? GFS is a little deeper with the low on this run and brings it into SFL then trains another, stronger low behind it.

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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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