Rains From Invest 96L Kill 55 in Mali

By: Dr. Jeff Masters , 3:40 PM GMT on August 31, 2013

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A tropical wave that emerged from the coast of Africa on Friday (Invest 96L) is headed west-northwest towards the Cape Verde Islands. This wave is struggling against high wind shear of 20 - 25 knots. The shear is expected to drop to the moderate level on Sunday, then increase again to the high level on Monday through Thursday. In their 8 am EDT Saturday Tropical Weather Outlook, NHC put the 5-day odds of development at 40%, and the 2-day odds at 40%. Our reliable models for tropical cyclone genesis show little or no development of 96L. This disturbance is unlikely to affect any land areas except the Cape Verde Islands.


Figure 1. MODIS satellite image of Invest 96L off the coast of Africa, taken at 8:30 am EDT on August 31, 2013. Image credit: NASA.

Disturbance 96L moved very slowly across the Sahel region of Africa during the week, dumping torrential rains on Wednesday that triggered flash floods that killed at least 55 people in Mali's capital city, Bamako. Serious flooding also affected neighboring Burkina Faso, Gambia, Guinea, Niger and Senegal. Buildings have collapsed, roads have been rendered impassable, and valuable farmland is submerged beneath flood water, affecting over 200,000 people. More than 100 homes were swept away as the Niger River burst its banks, bringing down bridges and submerging entire streets.


Figure 2. People hold a rope to help rescuers climbing down a roof of a house in a flooded area of Bamako, Mail, on August 28, 2013. At least 55 people have been killed in flash floods caused by torrential rain. Image credit: HABIBOU KOUYATE/AFP/Getty Images)


Figure 3. MODIS satellite image of tropical wave 96L over Mali on August 28, 2013. The storm dumped torrential rains on Mali's capital city, Bamako, which killed at least 55 people. Image credit: NASA.

Disturbance approaching Lesser Antilles no immediate threat to develop
A tropical wave located about 400 miles east of the Lesser Antilles Islands is moving westward at 15 mph, and has changed little over the past three days. The wave has a modest amount of spin, but only a limited amount of heavy thunderstorm activity. In their 8 am EDT Saturday Tropical Weather Outlook, NHC put the 5-day odds of formation of this disturbance at 10%, and the 2-day odds at 0%. Wind shear is a high 20 - 30 knots over the system, and is expected to stay high through Monday. An area of dry air and dust from the Saharan Air Layer (SAL) surrounds the disturbance and is interfering with development. Wind shear may fall to the moderate level in 4 - 5 days when the wave reaches the Central Caribbean, increasing the odds of development then. Of our three reliable models for predicting genesis, the UKMET, GFS, and European models, only the UKMET model develops the disturbance, predicting it will become a tropical depression south of Haiti on Thursday. The wave will spread heavy rains and gusty winds to the Lesser Antilles Islands on Sunday and Monday.

Jeff Masters

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1469. Relix
I don't think it'll make it before 63W. It will be a heavy rain event for PR though its staying south. More rain. Yay.
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something definitely occurring north to northwest of Barbados...
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Have to run now. Back this afternoon unless my game gets rained out :-(
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1466. GatorWX
Quoting 1463. kmanislander:


It has slowed it down already. I don't think it is so much they are competing. It is more a case that the rotation at the upper levels is not aligned with the surface circulation. If you look at the 850 mb vort map it stretches from NE to SW all the way to the coast of Venezuela and well below the area of strongest inflow to the NNW of Barbados.

What we need to see happen is for a strong symmetrical core of deep convection become dominant just around the area I have centered in the image below.That is the part of 97L that we need to follow, not what is East of there.





True true. Well you have a great day kman. See ya later if you're around.
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1465. hydrus
Quoting 1460. Sfloridacat5:
97L must stay south of the Islands to survive (or develop).
NAM is hinting at 97L smashing into Haiti/D.R. and weakening.

I also don't like to bet against the GFS. But the GFS has been late to the party with some systems this year.
Hispaniola is the cyclone shredder. That land mass has probably saved the U.S from many hurricane strikes at a great cost to the folks there.
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1464. GatorWX
Looks like it's awaiting its anticyclone further east in that wv. Piling up some like that will likely burn off a lot of that deep convection, but if it's moving as slow as it appears there, the anticyclone should catch up and more than help it overcome a break in deep convection.
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Quoting 1451. GatorWX:


Absolutely agree, but wouldn't you think, assuming the possibility dual circulations exist, they'll compete enough to slow it down? As you said, it likely has a small window for now.


It has slowed it down already. I don't think it is so much they are competing. It is more a case that the rotation at the upper levels is not aligned with the surface circulation. If you look at the 850 mb vort map it stretches from NE to SW all the way to the coast of Venezuela and well below the area of strongest inflow to the NNW of Barbados.

What we need to see happen is for a strong symmetrical core of deep convection become dominant just around the area I have centered in the image below.That is the part of 97L that we need to follow, not what is East of there.



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1462. GatorWX
Also, I posted earlier on this likely impediment. Notice the direction of shear and the appearance of 97. Lots of dry air sw of it.


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1461. hydrus
Quoting 1455. Grothar:


they moved more west
Could you please take the blue line off. TIA..Mornin Gro..:)
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97L must stay south of the Islands to survive (or develop).
NAM is hinting at 97L smashing into Haiti/D.R. and weakening.

I also don't like to bet against the GFS. But the GFS has been late to the party with some systems this year.
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1459. hydrus
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1458. GatorWX
Quoting 1455. Grothar:


they moved more west


Groth,

Hey guy! I don't like that blue one lol.
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So activity would reach my area as well I guess
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1456. GatorWX
Quoting 1447. kmanislander:


I have not had time to read back and can only stay on for a few more minutes but what I think we have going on is a stretched 850 mb vort which is responsible for the convection being linear in appearance while at the surface the circulation appears to be a lot tighter. This is holding it back from being able to focus all that energy where the low is centered but it may still get there by this evening.

Very interesting to see this unfold.


If you have a second, click that last sat pic I posted above vort maps, speed it all the way up. Sure looks like a circulation to me. Otherwise, enjoy golfing today, if that's still in your plans. :)
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1455. Grothar


they moved more west
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Looking better with some good lower convergence. The blowup of convection to the NE of the center is making its way over the dry spot as the center moves across the Lesser Antilles it should continue to organized and the ULL allow it to breathe.



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Quoting 1440. wunderkidcayman:


Wow 82kts hurricane ESE of us in Grand Cayman


Take another sip of coffee :-)
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1451. GatorWX
Quoting 1436. kmanislander:
The way to look at 97L is to appreciate that what actually constitutes the core of the system is the Western half and in particular the circulation just to the NNW of Barbados.

The convection East of there is actually trailing the low. I personally think 97L is organizing much faster than the NHC outlook gives it credit for. Those West wind obs tell us that it has done a lot of work overnight.


Absolutely agree, but wouldn't you think, assuming the possibility dual circulations exist, they'll compete enough to slow it down? As you said, it likely has a small window for now.
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Does anyone know why the ASCAT site isn't showing any data?

Anyway, 97L is looking better. Lots of deep convection to help it re-organize now. Shear is around 20kts above it, but if it can get another anticyclone it could potentially work through that and develop a bit faster.
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Can't say the intensity models aren't excited.
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1448. SLU
LGEM 103KTS in 120HRS
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Quoting 1432. GatorWX:


Morning kman,

Good luck today! What do think of my dual circulation theory I posted on? Stretched 850mb vort would seemingly support it, but hard to actually say with all the convection as to what's going on. At least we have radar for 14.5 62.


I have not had time to read back and can only stay on for a few more minutes but what I think we have going on is a stretched 850 mb vort which is responsible for the convection being linear in appearance while at the surface the circulation appears to be a lot tighter. This is holding it back from being able to focus all that energy where the low is centered but it may still get there by this evening.

Very interesting to see this unfold.
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Quoting 1443. wunderkidcayman:
12Z not much different from 06Z runs


Infact the models did shift further S and W
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Quoting 1438. SFLWeatherman:
The experts will always tell you,dont take the models seriously till something forms.If I did South Texas would be wiped out by a major hurricane from 92l
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1444. GatorWX
Quoting 1431. JLPR2:


Look at that! D-max was very good to 97L, the Low level circulation regained dominance while the weak mid-level spin we were watching last night was left behind. Now it needs to build up another one over the LLC but that shouldn't be much trouble considering it's finally under some heavy convection.


You think this is in the mid levels? Click and speed it up all the way. An obvious swirl at least.



Not a lot of help from maps.




This one shows a bit of energy at 500mb, which is what I assume is the old mlc:



On satellite, it^ seems evident, but dying fast.
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12Z not much different from 06Z runs

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1442. SLU
* ATLANTIC SHIPS INTENSITY FORECAST *
* GOES AVAILABLE, OHC AVAILABLE *
* INVEST AL972013 09/01/13 12 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 30 32 34 37 40 47 55 64 70 75 78 82 82
V (KT) LAND 30 32 34 37 40 47 55 64 70 75 78 82 82
V (KT) LGE mod 30 32 35 37 39 45 53 63 75 87 96 102 103

Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 6 6 9 8 6 11 2 9 4 13 6 10 9
SHEAR ADJ (KT) 0 -1 3 0 1 -3 0 -1 -2 -3 -3 -4 -4
SHEAR DIR 224 188 193 175 163 165 167 155 130 140 213 198 237
SST (C) 28.9 28.9 29.0 29.1 29.1 29.2 29.1 28.9 28.7 28.7 28.7 28.9 28.9
POT. INT. (KT) 151 150 151 153 153 154 153 150 147 148 148 151 150
ADJ. POT. INT. 150 145 146 149 148 150 148 146 144 145 144 146 144
200 MB T (C) -54.1 -53.6 -53.5 -53.7 -53.6 -53.3 -53.5 -53.1 -53.4 -53.1 -53.3 -53.0 -53.2
TH_E DEV (C) 10 12 12 11 11 11 10 11 10 11 11 12 12
700-500 MB RH 57 55 55 57 58 62 65 63 64 60 62 61 64
GFS VTEX (KT) 8 8 7 7 7 6 6 6 5 4 LOST LOST LOST
850 MB ENV VOR 19 22 28 29 35 52 64 69 69 68 61 44 33
200 MB DIV 34 43 33 22 19 29 18 29 30 22 25 12 -3
700-850 TADV -3 -3 -5 -3 -2 -2 -2 1 0 2 4 1 0
LAND (KM) 425 419 422 400 378 368 282 228 237 279 161 76 234
LAT (DEG N) 14.6 14.6 14.5 14.3 14.1 13.9 13.7 14.0 14.6 15.5 16.4 17.3 17.9
LONG(DEG W) 60.5 61.5 62.4 63.3 64.2 65.8 67.5 69.2 71.3 73.5 75.8 78.2 80.5
STM SPEED (KT) 12 9 9 9 8 8 8 9 11 12 12 12 11
HEAT CONTENT 43 39 42 43 48 48 44 48 51 43 50 39 58

FORECAST TRACK FROM BAMM INITIAL HEADING/SPEED (DEG/KT):270/ 15 CX,CY: -14/ 0
T-12 MAX WIND: 25 PRESSURE OF STEERING LEVEL (MB): 668 (MEAN=624)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 33.9 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 47.0 (MEAN=65.0)

INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
6 12 18 24 36 48 60 72 84 96 108 120
-------------------------------------------------- --------
SAMPLE MEAN CHANGE 1. 2. 3. 4. 6. 8. 9. 11. 12. 12. 13. 14.
SST POTENTIAL 0. 0. 1. 2. 6. 11. 17. 21. 25. 28. 30. 31.
VERTICAL SHEAR MAG 1. 2. 3. 5. 6. 8. 10. 11. 11. 12. 12. 11.
VERTICAL SHEAR ADJ 0. 0. 0. 0. 0. 1. 1. 1. 2. 2. 2. 2.
VERTICAL SHEAR DIR 0. -1. -2. -2. -3. -4. -4. -4. -3. -5. -6. -8.
PERSISTENCE 1. 1. 2. 2. 2. 2. 2. 1. 1. 0. 0. 0.
200/250 MB TEMP. 0. 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 2.
THETA_E EXCESS 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 2. 2.
700-500 MB RH 0. 0. 0. 0. 0. -1. -1. -1. -2. -2. -2. -1.
GFS VORTEX TENDENCY 0. 0. -1. -1. -2. -2. -3. -4. -6. -6. -6. -6.
850 MB ENV VORTICITY 0. 0. 0. 0. 0. 1. 1. 2. 2. 3. 3. 3.
200 MB DIVERGENCE 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
850-700 T ADVEC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
ZONAL STORM MOTION 0. 0. 1. 1. 2. 2. 2. 3. 3. 4. 4. 4.
STEERING LEVEL PRES 0. 0. 0. 0. 0. -1. 0. -1. -1. -1. -1. 0.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
GOES PREDICTORS -1. -1. -2. -2. -2. -2. -2. -2. -2. -1. -1. -1.
OCEAN HEAT CONTENT 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
-------------------------------------------------- --------
TOTAL CHANGE 2. 4. 7. 10. 17. 25. 34. 40. 45. 48. 52. 52.

** 2013 ATLANTIC RI INDEX AL972013 INVEST 09/01/13 12 UTC **
( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)

12 HR PERSISTENCE (KT): 5.0 Range:-49.5 to 33.0 Scaled/Wgted Val: 0.7/ 1.9
850-200 MB SHEAR (KT) : 7.2 Range: 28.8 to 2.9 Scaled/Wgted Val: 0.8/ 1.0
STD DEV OF IR BR TEMP : 33.9 Range: 37.5 to 2.9 Scaled/Wgted Val: 0.1/ 0.1
850-700 MB REL HUM (%): 67.2 Range: 43.2 to 93.5 Scaled/Wgted Val: 0.5/ 0.6
POT = MPI-VMAX (KT) : 117.5 Range: 28.4 to 139.1 Scaled/Wgted Val: 0.8/ 0.5
Heat content (KJ/cm2) : 43.0 Range: 0.0 to 155.1 Scaled/Wgted Val: 0.3/ 0.1
D200 (10**7s-1) : 30.2 Range:-23.1 to 181.5 Scaled/Wgted Val: 0.3/ 0.1
% area w/pixels <-30 C: 44.0 Range: 15.3 to 100.0 Scaled/Wgted Val: 0.3/ 0.1

Prob of RI for 25 kt RI threshold= 20% is 1.7 times the sample mean(11.9%)
Prob of RI for 30 kt RI threshold= 11% is 1.4 times the sample mean( 7.6%)
Prob of RI for 35 kt RI threshold= 1% is 0.3 times the sample mean( 4.6%)
Prob of RI for 40 kt RI threshold= 1% is 0.3 times the sample mean( 3.0%)

## ANNULAR HURRICANE INDEX (AHI) AL972013 INVEST 09/01/13 12 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL972013 INVEST 09/01/2013 12 UTC **
TIME(HR) 0-12 12-24(0-24) 24-36(0-36) 36-48(0-48)
CLIMO(%) 0 0( 0) 0( 0) 0( 0) <-- PROB BASED ON INTENSITY ONLY
PROB(%) 0 0( 0) 0( 0) 0( 0) PC4 UNAVAIL...MODEL SKILL DEGRADED


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1441. Kyon5
Quoting 1438. SFLWeatherman:

It's north of all the model guidance.

Edit. They just got updated.
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Quoting 1435. SLU:
* ATLANTIC SHIPS INTENSITY FORECAST *
* GOES AVAILABLE, OHC AVAILABLE *
* INVEST AL972013 09/01/13 12 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 30 32 34 37 40 47 55 64 70 75 78 82 82
V (KT) LAND 30 32 34 37 40 47 55 64 70 75 78 82 82
V (KT) LGE mod 30 32 35 37 39 45 53 63 75 87 96 102 103
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 6 6 9 8 6 11 2 9 4 13 6 10 9
SHEAR ADJ (KT) 0 -1 3 0 1 -3 0 -1 -2 -3 -3 -4 -4
SHEAR DIR 224 188 193 175 163 165 167 155 130 140 213 198 237
SST (C) 28.9 28.9 29.0 29.1 29.1 29.2 29.1 28.9 28.7 28.7 28.7 28.9 28.9
POT. INT. (KT) 151 150 151 153 153 154 153 150 147 148 148 151 150
ADJ. POT. INT. 150 145 146 149 148 150 148 146 144 145 144 146 144
200 MB T (C) -54.1 -53.6 -53.5 -53.7 -53.6 -53.3 -53.5 -53.1 -53.4 -53.1 -53.3 -53.0 -53.2
TH_E DEV (C) 10 12 12 11 11 11 10 11 10 11 11 12 12
700-500 MB RH 57 55 55 57 58 62 65 63 64 60 62 61 64
GFS VTEX (KT) 8 8 7 7 7 6 6 6 5 4 LOST LOST LOST
850 MB ENV VOR 19 22 28 29 35 52 64 69 69 68 61 44 33
200 MB DIV 34 43 33 22 19 29 18 29 30 22 25 12 -3
700-850 TADV -3 -3 -5 -3 -2 -2 -2 1 0 2 4 1 0
LAND (KM) 425 419 422 400 378 368 282 228 237 279 161 76 234
LAT (DEG N) 14.6 14.6 14.5 14.3 14.1 13.9 13.7 14.0 14.6 15.5 16.4 17.3 17.9
LONG(DEG W) 60.5 61.5 62.4 63.3 64.2 65.8 67.5 69.2 71.3 73.5 75.8 78.2 80.5
STM SPEED (KT) 12 9 9 9 8 8 8 9 11 12 12 12 11
HEAT CONTENT 43 39 42 43 48 48 44 48 51 43 50 39 58

FORECAST TRACK FROM BAMM INITIAL HEADING/SPEED (DEG/KT):270/ 15 CX,CY: -14/ 0
T-12 MAX WIND: 25 PRESSURE OF STEERING LEVEL (MB): 668 (MEAN=624)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 33.9 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 47.0 (MEAN=65.0)

INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
6 12 18 24 36 48 60 72 84 96 108 120
-------------------------------------------------- --------
SAMPLE MEAN CHANGE 1. 2. 3. 4. 6. 8. 9. 11. 12. 12. 13. 14.
SST POTENTIAL 0. 0. 1. 2. 6. 11. 17. 21. 25. 28. 30. 31.
VERTICAL SHEAR MAG 1. 2. 3. 5. 6. 8. 10. 11. 11. 12. 12. 11.
VERTICAL SHEAR ADJ 0. 0. 0. 0. 0. 1. 1. 1. 2. 2. 2. 2.
VERTICAL SHEAR DIR 0. -1. -2. -2. -3. -4. -4. -4. -3. -5. -6. -8.
PERSISTENCE 1. 1. 2. 2. 2. 2. 2. 1. 1. 0. 0. 0.
200/250 MB TEMP. 0. 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 2.
THETA_E EXCESS 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 2. 2.
700-500 MB RH 0. 0. 0. 0. 0. -1. -1. -1. -2. -2. -2. -1.
GFS VORTEX TENDENCY 0. 0. -1. -1. -2. -2. -3. -4. -6. -6. -6. -6.
850 MB ENV VORTICITY 0. 0. 0. 0. 0. 1. 1. 2. 2. 3. 3. 3.
200 MB DIVERGENCE 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
850-700 T ADVEC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
ZONAL STORM MOTION 0. 0. 1. 1. 2. 2. 2. 3. 3. 4. 4. 4.
STEERING LEVEL PRES 0. 0. 0. 0. 0. -1. 0. -1. -1. -1. -1. 0.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
GOES PREDICTORS -1. -1. -2. -2. -2. -2. -2. -2. -2. -1. -1. -1.
OCEAN HEAT CONTENT 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
-------------------------------------------------- --------
TOTAL CHANGE 2. 4. 7. 10. 17. 25. 34. 40. 45. 48. 52. 52.

** 2013 ATLANTIC RI INDEX AL972013 INVEST 09/01/13 12 UTC **
( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)

12 HR PERSISTENCE (KT): 5.0 Range:-49.5 to 33.0 Scaled/Wgted Val: 0.7/ 1.9
850-200 MB SHEAR (KT) : 7.2 Range: 28.8 to 2.9 Scaled/Wgted Val: 0.8/ 1.0
STD DEV OF IR BR TEMP : 33.9 Range: 37.5 to 2.9 Scaled/Wgted Val: 0.1/ 0.1
850-700 MB REL HUM (%): 67.2 Range: 43.2 to 93.5 Scaled/Wgted Val: 0.5/ 0.6
POT = MPI-VMAX (KT) : 117.5 Range: 28.4 to 139.1 Scaled/Wgted Val: 0.8/ 0.5
Heat content (KJ/cm2) : 43.0 Range: 0.0 to 155.1 Scaled/Wgted Val: 0.3/ 0.1
D200 (10**7s-1) : 30.2 Range:-23.1 to 181.5 Scaled/Wgted Val: 0.3/ 0.1
% area w/pixels <-30 C: 44.0 Range: 15.3 to 100.0 Scaled/Wgted Val: 0.3/ 0.1

Prob of RI for 25 kt RI threshold= 20% is 1.7 times the sample mean(11.9%)
Prob of RI for 30 kt RI threshold= 11% is 1.4 times the sample mean( 7.6%)
Prob of RI for 35 kt RI threshold= 1% is 0.3 times the sample mean( 4.6%)
Prob of RI for 40 kt RI threshold= 1% is 0.3 times the sample mean( 3.0%)

## ANNULAR HURRICANE INDEX (AHI) AL972013 INVEST 09/01/13 12 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL972013 INVEST 09/01/2013 12 UTC **
TIME(HR) 0-12 12-24(0-24) 24-36(0-36) 36-48(0-48)
CLIMO(%) 0 0( 0) 0( 0) 0( 0) <-- PROB BASED ON INTENSITY ONLY
PROB(%) 0 0( 0) 0( 0) 0( 0) PC4 UNAVAIL...MODEL SKILL DEGRADED




Wow 82kts hurricane ESE of us in Grand Cayman
Member Since: June 13, 2009 Posts: 2 Comments: 9598
1439. ncstorm
Good Morning..

Member Since: August 19, 2006 Posts: 13 Comments: 13481
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Quoting 1424. Neapolitan:
97L up to 30 knots:

AL, 97, 2013090112, , BEST, 0, 146N, 605W, 30, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1012, 200, 80, 0, 0, L, 0, , 0, 0, INVEST, M,


Good day WU, Its seems 97L is more organized than what it appears on satellite. The system is interacting with a area of disturb weather caused by the diffluent flow from the ULL. This is making it look elongated when its actually merging with the area that was over the Lesser Antilles yesterday. Which is why Stewart raise the odds to 20/30.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
The way to look at 97L is to appreciate that what actually constitutes the core of the system is the Western half and in particular the circulation just to the NNW of Barbados.

The convection East of there is actually trailing the low. I personally think 97L is organizing much faster than the NHC outlook gives it credit for. Those West wind obs tell us that it has done a lot of work overnight.
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1435. SLU
* ATLANTIC SHIPS INTENSITY FORECAST *
* GOES AVAILABLE, OHC AVAILABLE *
* INVEST AL972013 09/01/13 12 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 30 32 34 37 40 47 55 64 70 75 78 82 82
V (KT) LAND 30 32 34 37 40 47 55 64 70 75 78 82 82
V (KT) LGE mod 30 32 35 37 39 45 53 63 75 87 96 102 103
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 6 6 9 8 6 11 2 9 4 13 6 10 9
SHEAR ADJ (KT) 0 -1 3 0 1 -3 0 -1 -2 -3 -3 -4 -4
SHEAR DIR 224 188 193 175 163 165 167 155 130 140 213 198 237
SST (C) 28.9 28.9 29.0 29.1 29.1 29.2 29.1 28.9 28.7 28.7 28.7 28.9 28.9
POT. INT. (KT) 151 150 151 153 153 154 153 150 147 148 148 151 150
ADJ. POT. INT. 150 145 146 149 148 150 148 146 144 145 144 146 144
200 MB T (C) -54.1 -53.6 -53.5 -53.7 -53.6 -53.3 -53.5 -53.1 -53.4 -53.1 -53.3 -53.0 -53.2
TH_E DEV (C) 10 12 12 11 11 11 10 11 10 11 11 12 12
700-500 MB RH 57 55 55 57 58 62 65 63 64 60 62 61 64
GFS VTEX (KT) 8 8 7 7 7 6 6 6 5 4 LOST LOST LOST
850 MB ENV VOR 19 22 28 29 35 52 64 69 69 68 61 44 33
200 MB DIV 34 43 33 22 19 29 18 29 30 22 25 12 -3
700-850 TADV -3 -3 -5 -3 -2 -2 -2 1 0 2 4 1 0
LAND (KM) 425 419 422 400 378 368 282 228 237 279 161 76 234
LAT (DEG N) 14.6 14.6 14.5 14.3 14.1 13.9 13.7 14.0 14.6 15.5 16.4 17.3 17.9
LONG(DEG W) 60.5 61.5 62.4 63.3 64.2 65.8 67.5 69.2 71.3 73.5 75.8 78.2 80.5
STM SPEED (KT) 12 9 9 9 8 8 8 9 11 12 12 12 11
HEAT CONTENT 43 39 42 43 48 48 44 48 51 43 50 39 58

FORECAST TRACK FROM BAMM INITIAL HEADING/SPEED (DEG/KT):270/ 15 CX,CY: -14/ 0
T-12 MAX WIND: 25 PRESSURE OF STEERING LEVEL (MB): 668 (MEAN=624)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 33.9 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 47.0 (MEAN=65.0)

INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
6 12 18 24 36 48 60 72 84 96 108 120
-------------------------------------------------- --------
SAMPLE MEAN CHANGE 1. 2. 3. 4. 6. 8. 9. 11. 12. 12. 13. 14.
SST POTENTIAL 0. 0. 1. 2. 6. 11. 17. 21. 25. 28. 30. 31.
VERTICAL SHEAR MAG 1. 2. 3. 5. 6. 8. 10. 11. 11. 12. 12. 11.
VERTICAL SHEAR ADJ 0. 0. 0. 0. 0. 1. 1. 1. 2. 2. 2. 2.
VERTICAL SHEAR DIR 0. -1. -2. -2. -3. -4. -4. -4. -3. -5. -6. -8.
PERSISTENCE 1. 1. 2. 2. 2. 2. 2. 1. 1. 0. 0. 0.
200/250 MB TEMP. 0. 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 2.
THETA_E EXCESS 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 2. 2.
700-500 MB RH 0. 0. 0. 0. 0. -1. -1. -1. -2. -2. -2. -1.
GFS VORTEX TENDENCY 0. 0. -1. -1. -2. -2. -3. -4. -6. -6. -6. -6.
850 MB ENV VORTICITY 0. 0. 0. 0. 0. 1. 1. 2. 2. 3. 3. 3.
200 MB DIVERGENCE 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
850-700 T ADVEC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
ZONAL STORM MOTION 0. 0. 1. 1. 2. 2. 2. 3. 3. 4. 4. 4.
STEERING LEVEL PRES 0. 0. 0. 0. 0. -1. 0. -1. -1. -1. -1. 0.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
GOES PREDICTORS -1. -1. -2. -2. -2. -2. -2. -2. -2. -1. -1. -1.
OCEAN HEAT CONTENT 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
-------------------------------------------------- --------
TOTAL CHANGE 2. 4. 7. 10. 17. 25. 34. 40. 45. 48. 52. 52.

** 2013 ATLANTIC RI INDEX AL972013 INVEST 09/01/13 12 UTC **
( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)

12 HR PERSISTENCE (KT): 5.0 Range:-49.5 to 33.0 Scaled/Wgted Val: 0.7/ 1.9
850-200 MB SHEAR (KT) : 7.2 Range: 28.8 to 2.9 Scaled/Wgted Val: 0.8/ 1.0
STD DEV OF IR BR TEMP : 33.9 Range: 37.5 to 2.9 Scaled/Wgted Val: 0.1/ 0.1
850-700 MB REL HUM (%): 67.2 Range: 43.2 to 93.5 Scaled/Wgted Val: 0.5/ 0.6
POT = MPI-VMAX (KT) : 117.5 Range: 28.4 to 139.1 Scaled/Wgted Val: 0.8/ 0.5
Heat content (KJ/cm2) : 43.0 Range: 0.0 to 155.1 Scaled/Wgted Val: 0.3/ 0.1
D200 (10**7s-1) : 30.2 Range:-23.1 to 181.5 Scaled/Wgted Val: 0.3/ 0.1
% area w/pixels <-30 C: 44.0 Range: 15.3 to 100.0 Scaled/Wgted Val: 0.3/ 0.1

Prob of RI for 25 kt RI threshold= 20% is 1.7 times the sample mean(11.9%)
Prob of RI for 30 kt RI threshold= 11% is 1.4 times the sample mean( 7.6%)
Prob of RI for 35 kt RI threshold= 1% is 0.3 times the sample mean( 4.6%)
Prob of RI for 40 kt RI threshold= 1% is 0.3 times the sample mean( 3.0%)

## ANNULAR HURRICANE INDEX (AHI) AL972013 INVEST 09/01/13 12 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL972013 INVEST 09/01/2013 12 UTC **
TIME(HR) 0-12 12-24(0-24) 24-36(0-36) 36-48(0-48)
CLIMO(%) 0 0( 0) 0( 0) 0( 0) <-- PROB BASED ON INTENSITY ONLY
PROB(%) 0 0( 0) 0( 0) 0( 0) PC4 UNAVAIL...MODEL SKILL DEGRADED


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1432. GatorWX
Quoting 1430. kmanislander:


Good morning. It's not raining yet so all is not lost.

97L looking much better today but still not well organized. It is getting there though and at 60W there is still a very small window for this to become
classified before the historical cut off boundary of 63 West after which development odss tend to wait for the Western Caribbean. Based upon the NHC outlook though I doubt they will classify this as a TD unless there is some significant change to the overall structure during the next 12 to 24 hours.


Morning kman,

Good luck today! What do think of my dual circulation theory I posted on? Stretched 850mb vort would seemingly support it, but hard to actually say with all the convection as to what's going on. At least we have radar for 14.5 62.
Member Since: January 1, 2008 Posts: 0 Comments: 2386
1431. JLPR2
Quoting 1428. GatorWX:




Look at that! D-max was very good to 97L, the Low level circulation regained dominance while the weak mid-level spin we were watching last night was left behind. Now it needs to build up another one over the LLC but that shouldn't be much trouble considering it's finally under some heavy convection.
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Quoting 1419. GatorWX:


Poor kman and his golf excursion :(


Good morning. It's not raining yet so all is not lost.

97L looking much better today but still not well organized. It is getting there though and at 60W there is still a very small window for this to become
classified before the historical cut off boundary of 63 West after which development odss tend to wait for the Western Caribbean. Based upon the NHC outlook though I doubt they will classify this as a TD unless there is some significant change to the overall structure during the next 12 to 24 hours.
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215
WHXX01 KWBC 011213
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1213 UTC SUN SEP 1 2013

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 (AL972013) 20130901 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
130901 1200 130902 0000 130902 1200 130903 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 14.6N 60.5W 14.6N 62.6W 14.4N 64.6W 14.2N 66.2W
BAMD 14.6N 60.5W 14.9N 62.3W 14.9N 64.0W 14.9N 65.6W
BAMM 14.6N 60.5W 14.5N 62.4W 14.1N 64.2W 13.9N 65.8W
LBAR 14.6N 60.5W 14.9N 63.0W 15.1N 65.3W 15.3N 67.6W
SHIP 30KTS 34KTS 40KTS 47KTS
DSHP 30KTS 34KTS 40KTS 47KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
130903 1200 130904 1200 130905 1200 130906 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 13.9N 67.9W 14.6N 71.5W 16.5N 76.1W 18.0N 81.1W
BAMD 15.2N 67.4W 16.7N 71.6W 19.0N 76.1W 21.1N 79.9W
BAMM 13.7N 67.5W 14.6N 71.3W 16.4N 75.8W 17.9N 80.5W
LBAR 15.6N 70.0W 17.0N 74.8W 19.9N 79.4W 22.9N 82.8W
SHIP 55KTS 70KTS 78KTS 82KTS
DSHP 55KTS 70KTS 78KTS 82KTS

...INITIAL CONDITIONS...
LATCUR = 14.6N LONCUR = 60.5W DIRCUR = 270DEG SPDCUR = 15KT
LATM12 = 14.6N LONM12 = 57.5W DIRM12 = 270DEG SPDM12 = 15KT
LATM24 = 14.6N LONM24 = 54.5W
WNDCUR = 30KT RMAXWD = 80NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1012MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN
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1428. GatorWX


Member Since: January 1, 2008 Posts: 0 Comments: 2386
Quoting 1424. Neapolitan:
97L up to 30 knots:

AL, 97, 2013090112, , BEST, 0, 146N, 605W, 30, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1012, 200, 80, 0, 0, L, 0, , 0, 0, INVEST, M,

Yeah that's just about where I have this thing and also the pressure dropped 1mb as well
Member Since: June 13, 2009 Posts: 2 Comments: 9598

2004 Jeanne
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Quoting 1421. GatorWX:


Do you see what I was referring to ene of what you referenced?


The only thing I see with that area is the outer circulation being slightly elongated pointing into that area that you called out that's it the only strong spin is where I called out
Member Since: June 13, 2009 Posts: 2 Comments: 9598
97L up to 30 knots, while pressure is down another millibar:

AL, 97, 2013090112, , BEST, 0, 146N, 605W, 30, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1012, 200, 80, 0, 0, L, 0, , 0, 0, INVEST, M,
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WOW THE DISTURBANCE TTHE SE OF 97L LOOKS RATHER OMINOUS
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1422. Kyon5

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1421. GatorWX
Quoting 1416. wunderkidcayman:
I see LLCOC near 14.5N 59.9W


Do you see what I was referring to ene of what you referenced?
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1420. GatorWX
Morning Logic!
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1419. GatorWX
Quoting 1418. wunderkidcayman:

That's just great more rain


Poor kman and his golf excursion :(
Member Since: January 1, 2008 Posts: 0 Comments: 2386

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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.