Hawaii braces for Felicia; 99L near the Cape Verdes Islands may develop

By: Dr. Jeff Masters , 3:55 PM GMT on August 10, 2009

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A strong tropical wave (99L) is just south of the Cape Verdes Islands, 800 miles off the coast of Africa. This morning's QuikSCAT pass showed a nearly closed surface circulation, stretched out along one axis. The satellite saw winds of up to 45 mph in a band of heavy thunderstorms well south of the Cape Verdes Islands. The islands have seen winds of only 10 - 15 mph and some occasional rain showers thus far from the disturbance. Heavy thunderstorm activity associated with 99L died down this morning, but appears to be making a comeback late this morning. Wind shear is moderate, about 10 knots, and sea surface temperatures are moderately warm, about 27 - 28°C. There is a large area of dry air to 99L's north that is interfering with the storm's organization, though.


Figure 1. Current satellite image of disturbance 99L.

Wind shear is expected to be moderate, 5 - 15 knots, through Wednesday. SSTs will remain relatively constant at 27°C, but the dry, stable air of the Saharan AIr Layer (SAL) to 99L's north will be problem for it. NHC has given 99L a moderate (30 - 50% chance) of developing into a tropical depression by Wednesday morning, which is a reasonable forecast. Most of the models show some weak development, but none of them predict 99L will become a hurricane. It is too early to say if 99L will recurve north of the Lesser Antilles Islands or not, since it will be at least 5 days before the storm makes it that far. It is unusual, though, for storms forming this far north to make it all the way across the Atlantic to hit the Lesser Antilles Islands.

The GFS and ECMWF models are predicting the possible development of a new tropical wave coming off the coast of Africa late this week.

Felicia continues to weaken, but is a flash flooding threat to Hawaii
Tropical Storm Felicia has weakened steadily over the past 24 hours, thanks to cool sea surface temperatures and increasing shear. Recent satellite loops show that strong upper-level winds from the west have pushed the storm's heavy thunderstorm activity to the northeast side of the center, exposing the surface center as a swirl of low clouds. Felicia's relatively meager heavy thunderstorm activity is steadily moving away from the center of the storm.


Figure 2. History of hurricane activity over Hawaii since 1950. Hawaii islands have been hit by only 9 tropical cyclones of tropical depression or greater strength, with 4 others passing withing 75 miles of an island. Image credit: NOAA Coastal Services Center.

Sea surface temperatures (SSTs) under Felicia are 25°C, well below the 26°C threshold typically needed to sustain a hurricane. SSTs will slowly increase to 26°C by Tuesday. Wind shear has increased to a high 30 knots, and is expected to increase further to 40 knots by Tuesday. The high shear combined with the cool SSTs should continue to weaken Felicia today. I give a 30% chance that the shear will completely rip away Felicia's heavy thunderstorm activity by the time the storm reaches Hawaii, leaving only a swirl of low-level clouds that will not cause significant flooding problems. The wind speed probabilities forecast shows about a 25% chance Felicia will still be a weak tropical storm at 3 am Hawaiian time Tuesday morning, and a 15% chance the storm will have dissipated. If Felicia does hold together that long, it would be only the tenth tropical cyclone of tropical depression or higher strength to affect the islands since 1950 (Figure 2). Large swells from Felicia are already affecting the Big Island, and a high surf warning has been posted for east-facing shores of the Big Island and other Hawaiian islands. Felicia or its remnants may bring heavy rain, flash flooding, and mud slides to the islands beginning this afternoon, and a Flash Flood Watch has been posted for most of the islands.

Links to follow:
Long range radar from the Big Island
Wundermap for Hawaii

I'll have an update Tuesday morning.

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1139. NRAamy
JERRY!!

:)
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Ity do get fun in here at times, Keeper...I just scan until I find the good stuff...LOL
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1137. Patrap
Fine here in NOLa Ike..enjoying the summer.

Yeah,when I visited JSC last April..they wouldnt even consider my application for NASA.
Even with a wunderground reference.
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1136. ssmate
Quoting Patrap:
What I always find humorous after 3 years here,is the folks who think the only eyes on anything are here.

This a Blog,..an internet source.
Nothing is gonna sneak up and develop on anyone .

The Folks at the NHC,US Navy and other reliable sources are always on top the frays. Not anyone here.

We observe,banter and yack
24 7 365,but at the end of the day,..were Hobbyists at best,..

Theres no such thing as a amateur Met.

Either you are are arent.

Just like there no amateur astronauts,..


True Pat, but I'm a professional blogger.
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1135. Greyelf
Cotillion and Louisianaboy444 - thanks for the info! I'll be reading up on it.
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1134. KEEPEROFTHEGATE (Mod)
Quoting Floodman:
How are you, by the way, Keeper? Been a while
yes it has doing good just sitting back watchin whats going on this place has been a little zoo the past little while hard to have a conversation flood moves quick here
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Pat, my friend, how are you? You're breaking my heart, by the way; no amateur astronauts? Then my chances are slim, huh?
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Quoting Patrap:
What I always find humorous after 3 years here,is the folks who think the only eyes on anything are here.

This a Blog,..an internet source.
Nothing is gonna sneak up and develop on anyone .

The Folks at the NHC,US Navy and other reliable sources are always on top the frays. Not anyone here.

We observe,banter and yack
24 7 365,but at the end of the day,..were Hobbyists at best,..

Theres no such thing as a amateur Met.

Either you are are arent.

Just like there no amateur astronauts,..

Well said.
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Quoting pipelines:


Very unlikely. A tsunami is just energy moving in the water. While this energy does extend down to the thermocline, it doesn't cause the water to move at all at that level. A very small amount of water may be moved at the surface, but it is so little it is almost impossible to notice a tsunami in the open ocean at the surface.


Dr. Masters actually did a whole entry on this topic a long while back about the 2004 tsunami's effect on local and global weather conditions.

Tsunami Weather

...However, an examination of the sea surface temperature imagery from the days immediately following the earthquake shows that the tsunami had very little effect on the ocean temperature. While there was some minor cooling observed within 1 km of the shorelines closest to the earthquake's epicenter, by two days later, sea surface temperatures in the region showed no trace that anything unusual had happened. The impact of the tsunami on sea surface temperatures was less than that of a weak tropical storm! This is because while a tsunami can create tremendous waves and mixing of the water when it crashes ashore, this effect is limited to shallow waters 1 km or less from shore. The tsunami's impact in deep water is very limited. Satellite measurements of the tsunami's passage over the open ocean revealed a maximum wave height of only 50 cm (20 in), which caused very little stirring of the water over the open ocean. There is nothing at all to suggest that this tsunami, or any tsunami in recorded history, has had a significant impact on regional or global weather.

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1130. Walshy
Quoting Patrap:
What I always find humorous after 3 years here,is the folks who think the only eyes on anything are here.

This a Blog,..an internet source.
Nothing is gonna sneak up and develop on anyone .

The Folks at the NHC,US Navy and other reliable sources are always on top the frays. Not anyone here.

We observe,banter and yack
24 7 365,but at the end of the day,..were Hobbyists at best,..

Theres no such thing as a amateur Met.

Either you are are arent.

Just like there no amateur astronauts,..


I am a certified Met at NC State. Well, ill be back later tonight to see if the convection fires back up.
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hmmm what do you guys think about this
Link
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Quoting Drakoen:
Forecast to dissipate:


No surprises there...
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Quoting louisianaboy444:
you are correct, sir...,

yes but it wouldn't bring up cooler waters from the depths and disrupt the TCHP


Well not really, it wouldnt cause upwelling. Imagine a wave that moves accross all layers of different temperature without disturbing them, that's basically what I believe a tsunami would do based on my knowledge of the type of wave they are.
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even if the barbados AOI did survive through tonight once it gets into the central carribean upper level winds are not favorable for development. I don't get why you guys bash everything TWC says because dr. lyons was right about the unfavorable upper level winds
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1125. KEEPEROFTHEGATE (Mod)
Quoting ALCoastGambler:
Post #1086 pics will not upload on mine. Probably not from there but just throwing that out there.
its from FNMOC US NAVY site from norfolk virg. its safe just havn't updated there info
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Quoting ALCoastGambler:
Not blaming you KOTG just not sure where these virusesare coomiing from


WHOA! Viruses? What do you mean, viruses?
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Sky99 you were close, meaning that we are all learning here,ty Lousianaboy444.

.
Quoting louisianaboy444:
Shear is only 5 to 10 knots over the Antilles wave which is very favorable for development. However, something else is keeping it in check as there still is a lack of any well-established outflow, but because of my limited meteorological skill I cannot determine what the inhibiting factor is!

it needs more Upper Level Divergence or in other words an Anticyclone to help it breathe and create outflow
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1122. Patrap
Hiya Floodman,..always good to see Jerry's face in Mid August coming.
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1121. Drakoen
Forecast to dissipate:
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Amen, Pat! Amen...amen...and amen...
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I actually had asked a similar question here quite awhile ago about whether the drop in pressure from a typhoon could possibly facilitate an impending earthquake. I ended up corresponding with a professor who I believe was at one of the universities in Texas, but he couldn't direct me to any specific studies on it. I wonder if any have been done since then...

They had something similar i read about it was a show actually on History channel about this place in Alaska which they could use certain kind of beams to control weather in the trosphere...i dont know if it was Alpha beams or not but these two guys were doing a test and sent Alpha beams into the ground and 5 Minutes after they were done a 6.9 earthquake hit so the question was if the guys triggered the Earthquake with electromagnetic beams and they were saying that one day we could possibly make earthquakes
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Quoting ALCoastGambler:
Post #1086 pics will not upload on mine. Probably not from there but just throwing that out there.
Not blaming you KOTG just not sure where these virusesare coomiing from
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How are you, by the way, Keeper? Been a while
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Quoting Greyelf:

I actually had asked a similar question here quite awhile ago about whether the drop in pressure from a typhoon could possibly facilitate an impending earthquake. I ended up corresponding with a professor who I believe was at one of the universities in Texas, but he couldn't direct me to any specific studies on it. I wonder if any have been done since then...


Here's something I remember reading a little while ago, hope it helps somewhat:

"Can storms prevent nasty earthquakes? That's the suggestion of study showing that typhoons can trigger benign, "slow" quakes that ease the stress between tectonic plates.

Beneath Taiwan, a tectonic plate is diving under its neighbouring plate at one of the world's fastest rates. "You can almost watch them," says study co-author Alan Linde of the Carnegie Institution in Washington DC. Yet the island has had fewer big rumbles than you'd expect from such movement."

Link

Here has a little bit more:

Link

Not saying whether I agree with it or not, as it does seem quite far-fetched yet thought provoking in the same breath.
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Quoting KEEPEROFTHEGATE:
if its from navy site that i just posted its safe they just havn't updated there info


The Navy site has security cert errors; oddly most of the scientific sites posted by the military have security cert errors
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Quoting louisianaboy444:
you are correct, sir...,

yes but it wouldn't bring up cooler waters from the depths and disrupt the TCHP



not so much bring them up, as I understand it, as take them to shallower areas, as Flood said...
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Quoting louisianaboy444:
Heres a thought to ponder...If there is a developing Tropical Cyclone and a large tsunami passes under it can it have an effect on the system i mean i know a tsunami ain't much in mid ocean but could it stir up the water?


Very unlikely. A tsunami is just energy moving in the water. While this energy does extend down to the thermocline, it doesn't cause the water to move at all at that level. A very small amount of water may be moved at the surface, but it is so little it is almost impossible to notice a tsunami in the open ocean at the surface.
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1112. KEEPEROFTHEGATE (Mod)
Quoting nrtiwlnvragn:
Looks like TPC is expecting the Barbados AOI to dissipate.

what it should do as we get later in the evening hopefully
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1111. Patrap
What I always find humorous after 3 years here,is the folks who think the only eyes on anything are here.

This a Blog,..an internet source.
Nothing is gonna sneak up and develop on anyone .

The Folks at the NHC,US Navy and other reliable sources are always on top the frays. Not anyone here.

We observe,banter and yack
24 7 365,but at the end of the day,..were Hobbyists at best,..

Theres no such thing as a amateur Met.

Either you are are arent.

Just like there no amateur astronauts,..
Member Since: Posts: Comments:
Post #1086 pics will not upload on mine. Probably not from there but just throwing that out there.
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TCFA is still active but will be reissued/canceled 24 hours from the time of issuance (7 AM EDT tomorrow/1106Z).
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1107. KEEPEROFTHEGATE (Mod)
if its from navy site that i just posted its safe they just havn't updated there info
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ok guys what I think is that 99l will increase in heavy thunderstorm activity tonight then be upgraded to red at 8pm today or 2am tuesday
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you are correct, sir...,

yes but it wouldn't bring up cooler waters from the depths and disrupt the TCHP
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Looks like TPC is expecting the Barbados AOI to dissipate.

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1103. Greyelf
Quoting louisianaboy444:
Heres a thought to ponder...If there is a developing Tropical Cyclone and a large tsunami passes under it can it have an effect on the system i mean i know a tsunami ain't much in mid ocean but could it stir up the water?

I actually had asked a similar question here quite awhile ago about whether the drop in pressure from a typhoon could possibly facilitate an impending earthquake. I ended up corresponding with a professor who I believe was at one of the universities in Texas, but he couldn't direct me to any specific studies on it. I wonder if any have been done since then...
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Quoting TerraNova:


Good question...since tsunamis (whatever the plural of that is) tend to extend from the surface down through the deepest levels of the ocean, it might cause cooler water from the depths to surge up to the surface. Just an educated guess, though...


Not much mixing, from what I've read, until the feature finds a shallower area; the energy is realtively evenly spread through the water column and does not cause much by way of preturbation. I'd guess it wouldn't have much effect on development and wouldn't even if it did move a lot of cold water upward as the tend to move very quickly(surface speeds over 200 knts?)
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Quoting ALCoastGambler:
Guys just got another virus warning. Don't know where it came from though


Yeah my browser says this page has "security certificate errors". Somebody must have posted something from a restricted access site.
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It would basically move under all the other waves and leave the surface undisturbed.

...you are correct, sir...,
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1099. KEEPEROFTHEGATE (Mod)
Quoting extreme236:


There was a TCFA issued but I doubt it gets renewed tonight.
its for tonight as darkness falls it has to refire or its done
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Good question...since tsunamis (whatever the plural of that is) tend to extend from the surface down through the deepest levels of the ocean, it might cause cooler water from the depths to surge up to the surface. Just an educated guess, though...

yeah thats what i was thinking also i knew it would inhibit developement if anything
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Guys just got another virus warning. Don't know where it came from though
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Quoting louisianaboy444:
Heres a thought to ponder...If there is a developing Tropical Cyclone and a large tsunami passes under it can it have an effect on the system i mean i know a tsunami ain't much in mid ocean but could it stir up the water?


Doubtful, I dont think a moving tsunami wave would cause much upwelling since it is a different type of wave than surface waves cause by wind.

Tsunami's generally only move one direction away from the main energy source leaving waters relatively undisturbed till they get to shore. It would basically move under all the other waves and leave the surface undisturbed.

Of course I could be totally wrong, but that's the best description based on my understanding of tsunami's...which isnt much. haha
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1095. KEEPEROFTHEGATE (Mod)


AOI/XX/XXL
MARK
13.3N/59.4W
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1094. sctonya
I refreshed my page and got this: "To help protect your security, IE has blocked this website from displaying content with security certificate errors" Is someone posting bad links again?
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Quoting Floodman:


Apparently it's a new word, having something to do with the spin axis of Rick Moranis...maybe Canadian, huh?



...ah....that explains it...thanks ; )
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Outflow is the major inhibiting factor with the wave near Barbados

Yes Voricity levels are there in the 850 mb level but it is imbalanced...The convergence and divergence are the same if it can gain some divergence aloft which could happen with sustainable convection or an anticyclone then the low will be able to deepen and pressure could start falling....Looking at the maps it looks to be a mid level low it will have to deepen to make its way down to the surface
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Quoting KEEPEROFTHEGATE:
POSS T.C.F.A.
INV/99L/XX




There was a TCFA issued but I doubt it gets renewed tonight.
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Winds are starting to increase here in Barbados...just had a 35 mph gust
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Quoting presslord:
"aximoranic"

...just curious...from what language does this word come?


Apparently it's a new word, having something to do with the spin axis of Rick Moranis...maybe Canadian, huh?
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.