
INVEST 99L, 2009

A comparison between both Cape Verde systems. The image of TD 2 was the first to announce the upgrade. I think the NHC is being conservative, which is normal and understandable since the disturbance is so far away.
Moderator: S2k Moderators
which is a little odd given some models are tracking this over Cape Verde Islands in about 12-18hrs time.
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* ATLANTIC SHIPS INTENSITY FORECAST *
* GOES DATA MISSING, PROXY USED *
* OHC DATA AVAILABLE *
* INVEST AL992009 08/09/09 18 UTC *
TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 25 27 29 32 35 40 45 50 52 53 50 47 42
V (KT) LAND 25 27 29 32 35 40 45 50 52 53 50 47 42
V (KT) LGE mod 25 26 27 28 30 33 36 39 41 43 45 45 43
SHEAR (KT) 9 6 6 9 4 5 4 4 8 11 18 26 32
SHEAR DIR 29 340 345 336 270 282 231 219 219 245 253 245 259
SST (C) 27.1 26.9 26.7 26.5 26.2 25.9 25.8 25.7 25.8 25.9 26.3 26.5 26.7
POT. INT. (KT) 127 124 122 120 117 113 112 111 112 113 117 118 120
ADJ. POT. INT. 127 122 119 116 112 107 106 105 105 106 108 108 108
200 MB T (C) -52.2 -52.5 -52.9 -52.8 -52.4 -52.9 -52.6 -52.6 -52.3 -52.3 -52.2 -52.7 -53.0
TH_E DEV (C) 7 7 7 7 7 7 7 6 6 6 7 7 7
700-500 MB RH 65 61 60 58 57 57 52 53 48 48 44 46 47
GFS VTEX (KT) 11 11 12 12 12 12 12 13 12 13 10 10 9
850 MB ENV VOR 20 13 13 23 34 24 31 48 50 42 12 -8 -29
200 MB DIV 48 19 20 34 35 11 0 11 1 12 12 0 3
LAND (KM) 532 672 816 957 1099 1341 1585 1815 2050 2207 2129 2104 2110
LAT (DEG N) 14.1 14.6 15.0 15.5 15.9 16.6 17.4 18.0 18.9 19.6 20.5 21.4 22.3
LONG(DEG W) 22.4 23.8 25.1 26.4 27.7 29.9 32.1 34.2 36.5 38.7 41.0 42.8 44.4
STM SPEED (KT) 15 14 13 13 12 11 11 11 11 12 10 9 8
HEAT CONTENT 3 2 0 0 0 0 0 0 0 0 4 9 12
FORECAST TRACK FROM BAMM INITIAL HEADING/SPEED (DEG/KT):290/ 15 CX,CY: -13/ 5
T-12 MAX WIND: 25 PRESSURE OF STEERING LEVEL (MB): 599 (MEAN=624)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 17.0 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 59.0 (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. 11. 12. 13. 13.
SST POTENTIAL 0. 1. 1. 2. 4. 8. 13. 17. 20. 22. 23. 24.
VERTICAL SHEAR MAG 1. 2. 4. 5. 8. 11. 12. 13. 13. 12. 10. 7.
VERTICAL SHEAR DIR 0. 1. 1. 1. 0. -2. -3. -5. -6. -7. -8. -9.
PERSISTENCE 0. -1. -1. -1. -1. -1. -1. -1. -1. 0. 0. 0.
200/250 MB TEMP. 0. 0. -1. -1. -1. -2. -2. -2. -3. -3. -3. -3.
THETA_E EXCESS 0. -1. -1. -1. -2. -3. -4. -6. -8. -9. -11. -12.
700-500 MB RH 0. 0. 0. 0. 0. -1. -1. -1. -1. -1. -1. -1.
GFS VORTEX TENDENCY 0. 0. 0. 1. 0. 0. 1. 0. 0. -2. -2. -3.
850 MB ENV VORTICITY 0. 0. 0. 0. 0. 0. 0. 0. 1. 1. 0. 0.
200 MB DIVERGENCE 0. 0. 0. 0. 0. 0. -1. -1. -1. -1. -1. -1.
ZONAL STORM MOTION 0. 0. 1. 1. 2. 2. 3. 4. 4. 5. 5. 5.
STEERING LEVEL PRES 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. -1. -1. -1. 0. 0. -1.
GOES PREDICTORS 0. 0. 0. 0. 0. -1. -1. -2. -2. -2. -2. -1.
OCEAN HEAT CONTENT 0. 0. 0. 0. 0. 0. -1. -1. -1. -1. 0. 0.
----------------------------------------------------------
TOTAL CHANGE 2. 4. 7. 10. 15. 20. 25. 27. 28. 25. 22. 17.
** 2009 ATLANTIC RI INDEX AL992009 INVEST 08/09/09 18 UTC **
( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
12 HR PERSISTENCE (KT): 0.0 Range:-45.0 to 30.0 Scaled/Wgted Val: 0.6/ 1.3
850-200 MB SHEAR (KT) : 6.7 Range: 26.2 to 3.2 Scaled/Wgted Val: 0.8/ 1.1
D200 (10**7s-1) : 31.2 Range:-21.0 to 140.0 Scaled/Wgted Val: 0.3/ 0.5
POT = MPI-VMAX (KT) : 94.2 Range: 33.5 to 126.5 Scaled/Wgted Val: 0.7/ 0.4
850-700 MB REL HUM (%): 60.2 Range: 56.0 to 85.0 Scaled/Wgted Val: 0.1/ 0.1
% area w/pixels <-30 C: 999.0 Range: 16.0 to 100.0 Scaled/Wgted Val:999.0/999.0
STD DEV OF IR BR TEMP : 999.0 Range: 30.6 to 3.2 Scaled/Wgted Val:999.0/999.0
Heat content (KJ/cm2) : 1.0 Range: 0.0 to 130.0 Scaled/Wgted Val: 0.0/ 0.0
Prob of RI for 25 kt RI threshold= 999% is 999.0 times the sample mean(12.3%)
Prob of RI for 30 kt RI threshold= 999% is 999.0 times the sample mean( 8.0%)
Prob of RI for 35 kt RI threshold= 999% is 999.0 times the sample mean( 4.8%)
Sanibel wrote:Interesting to see what the negative conditions will do to it. Maybe nothing. Interesting to see that formation depends on getting over the hump of whatever inhibiting factors existed. I assume this favorability will migrate west.
jinftl wrote:What are the inhibiting factors short-term? Water is around 27C, shear is 10kts or less, SAL is to it's north.....the way it looks now, if anything, is a testament to the favorable conditions it is under.
Sanibel wrote:jinftl wrote:What are the inhibiting factors short-term? Water is around 27C, shear is 10kts or less, SAL is to it's north.....the way it looks now, if anything, is a testament to the favorable conditions it is under.
Not sure. But the last wave had a fairly good look before it vaporized. Perhaps it is a simple matter of the low pressure finally being driven by seasonal latent heat to the point where it is able to puncture and overcome the surrounding prevailing high pressure regime.
In any case the best indicator is always the disturbance itself. If dry subsiding conditions are still in place it will struggle.
jinftl wrote:The atmosphere is always in flux and clearly the hostile conditions have been replaced by more typical favorable conditions for the time of year. 99L may develop due to the conditions around it, not 'in spite of'....that is a first this season.
Sanibel wrote:jinftl wrote:The atmosphere is always in flux and clearly the hostile conditions have been replaced by more typical favorable conditions for the time of year. 99L may develop due to the conditions around it, not 'in spite of'....that is a first this season.
Whether the change of conditions is a part of the tropical "forcing" a stronger Low creates is beyond me. Either way there it is.
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