| Forecast to dissipate in the Atlantic. Track: http://www.nhc.noaa.gov/refresh/graphics_at4+shtml/143255.shtml?5day?large#contents At the moment, not even forecast to get a name. Floater: http://www.ssd.noaa.gov/PS/TROP/floaters/09L/09L_floater.html Wide view: http://www.ssd.noaa.gov/imagery/tatl.html TROPICAL DEPRESSION NINE DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092015 1100 AM AST WED SEP 16 2015 Organized convection associated with the area of low pressure in the central tropical Atlantic has now increased to the point that the system is considered a tropical cyclone. The initial intensity is 25 kt based on the latest Dvorak classifications and in agreement with earlier ASCAT wind data. Some southwesterly shear is already affecting the cyclone, with most of the convection displaced east and north of the estimated center position. The environment only becomes less favorable from this point forward, with the shear forecast to quickly increase in 12 to 24 hours and remain high through the remainder of the forecast period. In addition, the southwesterly flow aloft will bring dry mid- to upper-level air over the cyclone. As a result, only slight strengthening is shown in the NHC forecast following the trend of most of the intensity guidance. The cyclone is expected to weaken to a remnant low by 72 hours. After that time, the GFS and ECMWF models show the system weakening and perhaps opening up into a trough in about 5 days, so the official forecast shows dissipation at that time. The initial motion estimate is 340/07, as the depression is moving into a weakness in the Atlantic subtropical ridge. This north- northwestward to northwestward motion should continue for the next 2 to 3 days, with a turn toward the west-northwest forecast by 96 hours as the shallow cyclone comes under the steering influence of the low-level trade wind flow. The NHC track forecast is close to the middle of the guidance envelope and near a blend of the GFS and ECMWF forecasts. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 15.0N 43.1W 25 KT 30 MPH 12H 17/0000Z 16.0N 43.6W 25 KT 30 MPH 24H 17/1200Z 17.3N 44.1W 30 KT 35 MPH 36H 18/0000Z 18.5N 44.6W 30 KT 35 MPH 48H 18/1200Z 19.7N 45.6W 25 KT 30 MPH 72H 19/1200Z 22.0N 47.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 20/1200Z 24.0N 50.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 21/1200Z...DISSIPATED $$ Forecaster Brennan Shear forecast: * ATLANTIC SHIPS INTENSITY FORECAST * * IR SAT DATA AVAILABLE, OHC AVAILABLE * * NINE AL092015 09/16/15 12 UTC * TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120 V (KT) NO LAND 25 27 28 29 31 32 31 31 29 28 29 33 38 V (KT) LAND 25 27 28 29 31 32 31 31 29 28 29 33 38 V (KT) LGE mod 25 25 26 26 26 26 25 23 22 21 20 20 21 Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP SHEAR (KT) 9 8 11 18 24 26 30 26 29 36 22 20 6 SHEAR ADJ (KT) 3 5 6 6 1 7 3 5 5 0 4 -1 -1 SHEAR DIR 256 249 242 246 256 246 263 254 242 237 241 235 270 SST (C) 28.0 28.0 28.0 27.9 28.0 28.1 28.3 28.6 29.0 29.4 29.7 29.8 29.9 POT. INT. (KT) 135 135 135 134 136 137 140 144 151 157 163 165 167 ADJ. POT. INT. 128 126 126 125 126 126 127 131 136 140 145 148 148 200 MB T (C) -53.6 -53.5 -53.8 -54.1 -54.3 -54.4 -54.6 -54.7 -55.1 -55.2 -55.6 -55.3 -55.5 TH_E DEV (C) 8 8 8 8 8 8 8 8 8 9 9 9 10 700-500 MB RH 57 59 62 62 61 60 56 55 57 59 57 52 44 MODEL VTX (KT) 11 11 10 9 9 8 7 7 6 6 6 6 4 850 MB ENV VOR 36 30 32 30 22 21 19 29 21 34 35 57 44 200 MB DIV 48 70 76 57 47 21 1 7 26 16 47 8 -21 700-850 TADV 0 -1 0 2 7 5 3 1 1 1 0 0 0 LAND (KM) 1486 1517 1548 1591 1636 1735 1839 1927 1948 1888 1807 1677 1527 LAT (DEG N) 14.6 xx.x xx.x xx.x xx.x xx.x xx.x xx.x xx.x xx.x xx.x xx.x xx.x LONG(DEG W) 43.0 xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x STM SPEED (KT) 7 6 6 7 7 7 7 8 8 7 7 9 8 HEAT CONTENT 15 17 14 9 8 9 13 15 24 36 36 31 33 FORECAST TRACK FROM OFPI INITIAL HEADING/SPEED (DEG/KT):340/ 7 CX,CY: -1/ 7 T-12 MAX WIND: 25 PRESSURE OF STEERING LEVEL (MB): 628 (MEAN=624) GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 19.3 (MEAN=14.5) % GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 80.0 (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. 1. 1. 2. 6. 11. 16. 21. 25. 28. 31. 32. VERTICAL SHEAR MAG 1. 2. 3. 4. 4. 2. -2. -6. -11. -14. -14. -13. VERTICAL SHEAR ADJ 0. -1. -1. -1. -2. -3. -3. -4. -4. -3. -3. -2. VERTICAL SHEAR DIR 0. -1. -2. -3. -5. -7. -8. -10. -10. -11. -12. -12. PERSISTENCE 0. -1. -1. -1. -1. -1. -1. -1. -1. 0. 0. 0. 200/250 MB TEMP. 0. 0. 0. 0. 1. 2. 3. 4. 5. 6. 8. 10. THETA_E EXCESS 0. 0. -1. -1. -1. -2. -3. -4. -5. -5. -6. -6. 700-500 MB RH 0. 0. 0. 0. -1. -1. -1. -1. -1. -1. -1. -1. MODEL VTX TENDENCY 0. 0. -1. -2. -3. -5. -5. -6. -6. -7. -7. -9. 850 MB ENV VORTICITY 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1. 200 MB DIVERGENCE 0. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 0. 850-700 T ADVEC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. ZONAL STORM MOTION 0. 0. 0. 0. 0. 0. -1. -1. -1. -2. -2. -2. 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. 0. 0. 0. 0. 0. 0. GOES PREDICTORS 1. 1. 2. 2. 2. 2. 1. 1. 0. 0. 0. 1. OCEAN HEAT CONTENT 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. ---------------------------------------------------------- TOTAL CHANGE 2. 3. 4. 6. 7. 6. 6. 4. 3. 4. 8. 13. ** 2013 ATLANTIC RI INDEX AL092015 NINE 09/16/15 12 UTC ** ( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR) 12 HR PERSISTENCE (KT): 0.0 Range:-49.5 to 33.0 Scaled/Wgted Val: 0.6/ 1.7 850-200 MB SHEAR (KT) : 13.9 Range: 28.8 to 2.9 Scaled/Wgted Val: 0.6/ 0.7 STD DEV OF IR BR TEMP : 19.3 Range: 37.5 to 2.9 Scaled/Wgted Val: 0.5/ 0.7 850-700 MB REL HUM (%): 68.0 Range: 43.2 to 93.5 Scaled/Wgted Val: 0.5/ 0.6 POT = MPI-VMAX (KT) : 101.4 Range: 28.4 to 139.1 Scaled/Wgted Val: 0.7/ 0.4 Heat content (KJ/cm2) : 12.6 Range: 0.0 to 155.1 Scaled/Wgted Val: 0.1/ 0.0 D200 (10**7s-1) : 59.6 Range:-23.1 to 181.5 Scaled/Wgted Val: 0.4/ 0.1 % area w/pixels <-30 C: 72.0 Range: 15.3 to 100.0 Scaled/Wgted Val: 0.7/ 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= 6% is 1.2 times the sample mean( 4.6%) Prob of RI for 40 kt RI threshold= 4% is 1.4 times the sample mean( 3.0%) ## ANNULAR HURRICANE INDEX (AHI) AL092015 NINE 09/16/15 12 UTC ## ## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=3 NFAIL=4 ## ## 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 AL092015 NINE 09/16/2015 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) <-- FULL MODEL PROB (RAN NORMALLY) ftp://ftp.nhc.noaa.gov/atcf/stext/ |