An Atlantic tropical wave worth watching

By: Dr. Jeff Masters , 2:46 PM GMT on October 04, 2009

Share this Blog
2
+

A large tropical wave near 9N 40W, midway between Africa and the Lesser Antilles Islands, is generating a considerable amount of heavy thunderstorm activity as it moves west to west-northwest at 15 mph. The wave is under about 10 - 15 knots of wind shear, and this morning's QuikSCAT pass showed a large and disorganized region of converging winds in the region, with top winds of 25 mph. There is very little dry air in the vicinity, and conditions appear favorable for some slow development of this wave. None of the computer models develop the wave, but they do show relatively low wind shear along the wave's path for the next five days. The wave should reach the Lesser Antilles Islands by Wednesday.


Figure 1. The large tropical wave in the middle Atlantic.

In the Philippines, Tropical Storm Parma continues to linger offshore the northern tip of the Philippines' Luzon Island, bringing heavy rain. The storm has been blamed for the deaths of 17 people in the Philippines, but has not not had the devastating impact that was earlier feared. Parma's heaviest rains will stay offshore of the Philippines today (Figure 2).


Figure 2. Forecast rain amounts for Parma for the 24-hour period ending at 06 UTC October 5 (2am EDT Monday). This forecast is based on satellite measurements of Parma's current rainfall rate, plus a projection of the storm's path. Four to eight inches of rain (yellow colors) is expected along the extreme northwest tip of Luzon Island. Image credit: NOAA Satellite Services Division.

Super Typhoon Melor hits Cat 5 strength
Super Typhoon Melor has become the second Category 5 tropical cyclone of the year. Melor is expected to recurve to the north pass just south of the coast of Japan later this week.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 939 - 889

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24Blog Index

939. xcool



Member Since: Posts: Comments:
I had to rub my eyes, twice, we have Grace outta nowhere lol.
Member Since: September 6, 2009 Posts: 2 Comments: 3709
Quoting JRRP:

91L?


Member Since: Posts: Comments:
I-90 in E. Washington closed due to blowing dust
Member Since: June 28, 2006 Posts: 24 Comments: 8185
To be clear to everyone…dwelling on past perceived unreliable forecasts (i.e. unnamed storms) by the NHC is just banging your head against a wall. Just wait till the post-season analysis. It just gets so repetitious sometimes. You were right about Grace…but going back to the beginning of the season and still questioning is a bit too much.
Member Since: Posts: Comments:
933. JRRP
Quoting StormW:


Didn't detect anything on close-up JSL or Shortwave yet...however, there is a decent vort max at the 850mb level near 9N;56W.

Looks like it'll be time to go to work in the a.m. Shear has been on the decrease over 91L.

estaba bien perdido
Member Since: Posts: Comments:
Since 91L has been activated the NHC will most likely bump it up to orange at 2am.
Member Since: Posts: Comments:
Quoting Tazmanian:



why not you go read some post be for you ask that ?s then you no or better yet go too the
Tropical weather pages then you will no evere thing that is going on out there


all ways look back at the postes be for you start asking ?s


sheesh
Member Since: June 28, 2006 Posts: 24 Comments: 8185

AOI

AOI

AOI

AOI

Special Notice (AussieStorm/Caritas)

Daily Chuckles in Comments section
Member Since: Posts: Comments:
Quoting WeatherStudent:
Do we now have 91L out there, folks?
yep and forecasted to become a 68 kts storm in 120 hrs from now
Member Since: Posts: Comments:
927. xcool



91L
Member Since: Posts: Comments:
926. JLPR
Quoting WeatherStudent:


WOW, interesting model tracks there, eh?


yep
although there are only three models xD
Member Since: Posts: Comments:
Quoting WeatherStudent:
Do we now have 91L out there, folks?



why not you go read some post be for you ask that ?s then you no or better yet go too the
Tropical weather pages then you will no evere thing that is going on out there


all ways look back at the postes be for you start asking ?s
Member Since: Posts: Comments:
What an interesting night.

A controversial TS declared and an invest declared.
Member Since: Posts: Comments:
Quoting StormW:


MJO RMM1

CLIMATE PREDICITON CENTER


StormW, thanks for the links :)

I am new to that MJO RMM1 map. I can locate the dates on the map, but what do the regions of the map indicate?

Member Since: Posts: Comments:
Good night. Tropics popping now.
Member Since: Posts: Comments:
CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

0331 UTC MON OCT 5 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL912009) 20091005 0000 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

091005 0000 091005 1200 091006 0000 091006 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 11.2N 42.9W 12.9N 46.1W 14.7N 49.3W 16.4N 52.8W

BAMD 11.2N 42.9W 12.5N 45.8W 14.2N 48.3W 16.0N 50.7W

BAMM 11.2N 42.9W 12.4N 46.0W 13.9N 48.8W 15.3N 51.7W

LBAR 11.2N 42.9W 12.3N 45.9W 13.6N 48.9W 14.9N 51.8W

SHIP 25KTS 28KTS 35KTS 42KTS

DSHP 25KTS 28KTS 35KTS 42KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

091007 0000 091008 0000 091009 0000 091010 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 18.2N 55.7W 20.1N 60.3W 20.4N 64.1W 18.7N 68.3W

BAMD 18.0N 52.5W 21.2N 54.1W 21.8N 54.7W 19.6N 54.9W

BAMM 16.8N 54.2W 18.3N 58.4W 18.4N 63.7W 17.0N 69.2W

LBAR 16.9N 54.4W 20.4N 57.1W 23.0N 55.9W 21.3N 50.5W

SHIP 50KTS 56KTS 60KTS 68KTS

DSHP 50KTS 56KTS 60KTS 68KTS



...INITIAL CONDITIONS...

LATCUR = 11.2N LONCUR = 42.9W DIRCUR = 280DEG SPDCUR = 16KT

LATM12 = 10.6N LONM12 = 39.6W DIRM12 = 280DEG SPDM12 = 15KT

LATM24 = 10.2N LONM24 = 36.8W

WNDCUR = 25KT RMAXWD = 30NM WNDM12 = 25KT

CENPRS = 1009MB OUTPRS = 1011MB OUTRAD = 175NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNN
Member Since: Posts: Comments:
916. JLPR
and then there is 91L

Member Since: Posts: Comments:
Quoting stormpetrol:
What the heck happened, I go from my computer for a few hours come back, and we have TS Grace & Invest 91?!
Its been a storm for days , NHC, finally admitted, that's all.
Member Since: July 31, 2008 Posts: 0 Comments: 730
I would like your opinion on 91L P451...
Member Since: Posts: Comments:
912. xcool
Member Since: Posts: Comments:
Quoting P451:


Now to me this point of view is of interest. (I am quite tired I will try to explain why as best I can).

One the one hand (let us revisit the NJ hybrid) you felt you would name that system based on temperature analysis and felt that despite it having a continued frontal relationship that it should have been named.

Now on this hand you feel that despite the system structure supporting a tropical entity that due to the SST it is presently over you would not support naming it.

Given that in both cases it would seem you are focusing more on temperature and less on structure - what about temperature difference?

What if the water is 70F but the upper atmosphere is extremely cool? Would you not theoretically have the same processes working in favor of being a "tropical" system?

I cite winter thunderstorms. We associated a thunderstorm with 80F surface temperatures and 0F (and much less) upper atmospheric temperatures.

Well, what if we have a surface temperature of 0F and an upper atmosphere temperature of -80F and less?

Would this not allow the same processes to occur?

....again, I'm hanging on by a thread here, so this probably isn't worded very well.



Here is a paper to support that theory (I think you can find this paper in Google)

Kwan-yin Kong. Understanding the Genesis of Hurricane Vince Through the Surface Pressure Tendency Equation . City College of New York.

This paper suggests a new paradigm in the thinking of how hurricanes form and develop.

Here is the current way we think: Deep bursts of convection over the center release latent heat, creating a strengthening vertical warm core over the center. A warmed column of air leads to low surface pressure (cyclonic spin at the surface) and high upper air pressure (upper anticyclone with cirrus outflow).

Here is the way this paper alters the thinking: Deep bursts of convection causes the central column of air to have a moist super-adiabatic lapse rate, thus resulting in a statically unstable atmosphere. The statically unstable atmosphere at the core of a hurricane causes air parcels to rise, causing low surface pressure and higher upper air pressure.

Now, this may explain why you can have a hurricane below 26 deg C water. All you need is to have a significantly unstable lapse rate to cause surface pressure falls. Over cooler sea surfaces, a cold core upper low over a deeply-occluded surface cyclone can allow for a super-unstable lapse rate due to the temp difference btn. the sea surface and cold core upper low.

I may have a post on this on my blog later this week (talk about skew-T diagrams, etc., so that this is understandable).
Member Since: Posts: Comments:
Quoting StormW:


Didn't detect anything on close-up JSL or Shortwave yet...however, there is a decent vort max at the 850mb level near 9N;56W.

Looks like it'll be time to go to work in the a.m. Shear has been on the decrease over 91L.


LOL...I just took the pup out for a quick walk and we have 91L! Thank you StormW for all you do and have a good night. I think you will be busy also tomorrow!
Member Since: Posts: Comments:
Member Since: Posts: Comments:


AOI/XX/XX
MARK
12.1N/55.2W
Member Since: Posts: Comments:
Quoting Weather456:


In one of the PDF presentation on cyclone types, it stated that cyclones occur on a spectrum so indeed they don't jump across the spectrum from extra tropical to tropical. They have to go through a transition (subtropical). Now, I agree that the NHC does go from extra tropical to tropical, no questions there. But in 2002, did not they started to name subtropical cyclones? So to only designate a system after it completely became tropical is not that an inconsistency in their naming policies. In addition, why name Jerry a subtropical system before it became tropical, why not name Jerry after it became fully tropical.



In the majority of cases systems go from tropical to extratropical with no designation of subtropical. If your premise is correct, then ALL systems going through extratropical transistion would have to have the three step process. That is not the current practice.
Member Since: Posts: Comments:
What the heck happened, I go from my computer for a few hours come back, and we have TS Grace & Invest 91?!
Member Since: Posts: Comments:
902. JLPR
Quoting JRRP:


looking ...wow xD
lets see if some consolidation and better spin occur tonight
Member Since: Posts: Comments:
901. beell
Night 456
Gone also.
Member Since: Posts: Comments:
Besides TS Grace this evening, there are also some posts about things getting interesting in the tropical latitudes.

We've got a good looking tropical wave with a nice 200 mb anticyclone above it. Also, there is a huge 200 mb anticyclone spreading in from the west into the Gulf of Mexico and Caribbean. Is that huge anticyclone coming in from the west associated with the MJO in some way? Does anyone have a website where the MJO is trackable?
Member Since: Posts: Comments:
898. 789
no trolls for the last 3 or 4 pages good times! thanks 456 ,stormW been fun
Member Since: Posts: Comments:
Get some rest 456!!!!! We will need you tomorrow!!
Member Since: Posts: Comments:
896. beell
Quoting nrtiwlnvragn:
NHC has updated the best track file on Grace to reflect a Tropical Storm since yesterday this morning at 12Z.

AL 09 2009100406 BEST 0 387N 295W 40 994 EX
AL 09 2009100412 BEST 0 383N 268W 45 993 TS
AL 09 2009100418 BEST 0 388N 239W 50 992 TS
AL 09 2009100418 BEST 0 388N 239W 50 992 TS
AL 09 2009100500 BEST 0 402N 213W 55 990 TS
AL 09 2009100500 BEST 0 402N 213W 55 990 TS


Well there ya go-a compromise lol.
Thanks, nrt!
Member Since: Posts: Comments:
Quoting AllStar17:


Did you get the mail?


yea. and I do understand, I use to make them. I posted this on my blog in June 2006



Now I really have to go.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Night 456...looks like you will be busy on Monday!
Member Since: Posts: Comments:
892. amd
Quoting 1900hurricane:

Yeah, I see that, although I'm not sure if it is due to the ingestion of dry air or if it is merely a convective inconsistency due the the EWRC. Whatever it is though, it will show itself soon as Melor either weakens or strengthens.


looks like it was just a convective inconsistency due to the EWRC. In fact, I wonder if Melor is going to try to become an annular super typhoon soon.

Latest Water Vapor Image for Melor
Member Since: Posts: Comments:
Quoting Weather456:
Night all


night 456
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting Weather456:
Night all


Did you get the mail?
Member Since: Posts: Comments:

Viewing: 939 - 889

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24Blog Index

Top of Page

About JeffMasters

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