1WTNT43 KNHC 100244 2TCDAT3 3 4TROPICAL STORM HENRI DISCUSSION NUMBER 5 5NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015 61100 PM AST WED SEP 09 2015 7 8Recently received ASCAT-B scatterometer data showed an area of 35-40 9kt wind vectors in the convection about 75-100 n mi east of the 10center. Based on this, the initial intensity is increased to a 11possibly conservative 35 kt and the cyclone is upgraded to a 12tropical storm. Despite the upgrade, Henri remains a disorganized 13system, with the low-level center remaining exposed to the west of 14the convection due to 15-20 kt of shear. In addition, microwave 15satellite data and experimental European multispectral satellite 16imagery suggest a tongue of dry air is entraining into the cyclone 17around the west, south, and southeast sides of the circulation. 18 19Henri has started its expected northward track with the initial 20motion of 355/4. For the next 36-48 hours, the cyclone should move 21generally northward with an increase in forward speed between the 22subtropical ridge to the east and a deep-layer trough moving 23eastward through the eastern United States. After that time, Henri 24should turn northeastward and eastward as it enters the westerlies. 25The new forecast track is similar to the previous track, but it lies 26a little south of the center of the guidance envelope after 36 hours 27due to a northward shift in the guidance. 28 29The dynamical models suggest that the shear should subside during 30the next 36-48 hours, and that the dry air entrainment should also 31decrease. This combination should allow Henri to strengthen until 32it reaches colder sea surface temperatures north of the Gulf Stream 33in a little under 48 hours. After that, the cyclone is expected to 34become extratropical as it merges with a frontal system. The new 35intensity forecast calls for a peak intensity near 50 kt in 36-48 36hours, followed by gradual weakening. The first 48 hours are in 37best agreement with the SHIPS model, and the intensities after 38extratropical transition are based on input from the NOAA Ocean 39Prediction Center. 40 41FORECAST POSITIONS AND MAX WINDS 42 43INIT 10/0300Z 31.3N 60.7W 35 KT 40 MPH 44 12H 10/1200Z 32.8N 60.9W 40 KT 45 MPH 45 24H 11/0000Z 35.3N 60.9W 45 KT 50 MPH 46 36H 11/1200Z 38.6N 60.2W 50 KT 60 MPH 47 48H 12/0000Z 42.4N 58.0W 50 KT 60 MPH 48 72H 13/0000Z 47.5N 48.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 49 96H 14/0000Z 47.5N 32.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 50120H 15/0000Z 47.0N 17.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 51 52$$ 53Forecaster Beven 54 55 56 57------------=_1441853120-44332-347 58Content-Type: text/plain; charset="US-ASCII" 59Content-Disposition: inline 60Content-Transfer-Encoding: 7BIT 61 62= = = == = = 63WTNT43 KNHC 100836 64TCDAT3 65 66TROPICAL STORM HENRI DISCUSSION NUMBER 6 67NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015 68500 AM AST THU SEP 10 2015 69 70There has been little change in the cloud pattern of Henri since 71the previous advisory. The tropical storm remains sheared with the 72low-level center displaced to the west of the main area of deep 73convection. The initial wind speed is held at 35 kt, which could 74be conservative based on the earlier scatterometer data. This 75intensity estimate is on the high side of the latest Dvorak 76analyses. 77 78Henri is currently being affected by 15-20 kt of west-southwesterly 79wind shear and dry air has wrapped around the west and south sides 80of the circulation. The shear is expected to lessen later today, 81and that could allow Henri to gain some strength. However, 82significant intensification is not expected as the cyclone should 83cross the north wall of the Gulf Stream in 36-48 hours, where a 84sharp gradient in sea surface temperatures exist. Henri is forecast 85to lose tropical characteristics in a little over 2 days, when it is 86expected to be over cold water. Most of the guidance shows the 87extratropical low dissipating by day 5, and the NHC forecast 88follows suit. 89 90The tropical storm has been moving erratically during the last 91several hours, but the general motion has been slowly northward. A 92faster northward motion is expected to begin later today and 93continue for the next 24 to 36 hours as a subtropical ridge 94strengthens to the east of Henri. After that time, an even faster 95northeastward and then eastward motion is predicted when the cyclone 96becomes embedded in the mid-latitude westerlies. The models are in 97good agreement on this overall scenario, and little change was made 98to the previous track forecast. 99 100The latter part of this forecast, when the storm is expected to be 101post-tropical, is based on guidance provided by NOAA's Ocean 102Prediction Center. 103 104FORECAST POSITIONS AND MAX WINDS 105 106INIT 10/0900Z 31.4N 61.0W 35 KT 40 MPH 107 12H 10/1800Z 33.0N 61.3W 40 KT 45 MPH 108 24H 11/0600Z 35.9N 60.9W 45 KT 50 MPH 109 36H 11/1800Z 39.3N 59.7W 50 KT 60 MPH 110 48H 12/0600Z 43.0N 56.5W 45 KT 50 MPH 111 72H 13/0600Z 48.0N 45.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 112 96H 14/0600Z 46.5N 29.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 113120H 15/0600Z...DISSIPATED 114 115$$ 116Forecaster Cangialosi 117 118 119 120------------=_1441874227-44332-424 121Content-Type: text/plain; charset="US-ASCII" 122Content-Disposition: inline 123Content-Transfer-Encoding: 7BIT 124 125= = = == = = 126WTNT43 KNHC 101435 127TCDAT3 128 129TROPICAL STORM HENRI DISCUSSION NUMBER 7 130NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015 1311100 AM AST THU SEP 10 2015 132 133The cloud pattern of Henri remains disorganized with most of the 134convection sheared off to the east and northeast of the center. 135Visible images also indicate that the system has little organization 136in the central core, with multiple smaller vortices rotating around 137a mean center. The initial wind speed remains 35 kt, although some 138Dvorak estimates suggest it could have weakened to a tropical 139depression. 140 141Southwesterly shear and dry air is currently limiting the amount of 142deep convection near the center of the cyclone. Global models, 143however, all weaken the shear later today, which could allow Henri 144to strengthen while it moves over warm waters before it crosses the 145north wall of the Gulf Stream in 36-48 hours. Henri is still 146forecast to lose tropical characteristics in a little over 2 days 147and then weaken while it moves over very cold water with high 148shear. The intensity guidance is in relatively good agreement on 149this scenario and the NHC forecast is very close to the previous 150one. 151 152Satellite fixes indicate that Henri is moving northward at about 8 153kt. The storm should accelerate northward today and northeastward 154tomorrow as it encounters faster steering from the subtropical 155ridge. After that time, an even faster northeastward and then 156eastward motion is predicted when the cyclone becomes embedded in 157the mid-latitude westerlies. There have been no significant changes 158to the guidance, and the NHC track forecast is basically just an 159update of the previous prediction. 160 161The latter part of this forecast, when the storm is expected to be 162post-tropical, is based on guidance provided by NOAA's Ocean 163Prediction Center. 164 165 166FORECAST POSITIONS AND MAX WINDS 167 168INIT 10/1500Z 32.6N 60.8W 35 KT 40 MPH 169 12H 11/0000Z 34.5N 60.7W 40 KT 45 MPH 170 24H 11/1200Z 37.8N 60.0W 45 KT 50 MPH 171 36H 12/0000Z 41.4N 58.2W 45 KT 50 MPH 172 48H 12/1200Z 45.0N 53.5W 45 KT 50 MPH 173 72H 13/1200Z 49.0N 41.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 174 96H 14/1200Z 45.5N 22.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 175120H 15/1200Z...DISSIPATED 176 177$$ 178Forecaster Blake 179 180 181 182------------=_1441895768-44332-558 183Content-Type: text/plain; charset="US-ASCII" 184Content-Disposition: inline 185Content-Transfer-Encoding: 7BIT 186 187= = = == = = 188WTNT43 KNHC 102033 189TCDAT3 190 191TROPICAL STORM HENRI DISCUSSION NUMBER 8 192NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015 193500 PM AST THU SEP 10 2015 194 195Henri continues to struggle with most of its deep convection well 196removed to the northeast of the center. In fact, it is taking on 197some characteristics of a subtropical cyclone with recent 198scatterometer data indicating that the radius of maximum winds has 199increased to a rather high value of 120 n mi. The initial wind 200speed will remain 35 kt on the basis of 30-35 kt winds observed in 201partial scatterometer pass that missed the area that likely 202has the strongest winds. 203 204Southerly shear is still forecast to relax overnight near Henri, 205which theoretically could result in intensification during the next 206day or so before the cyclone moves over cold water on Saturday. 207However, dry air aloft persists near the storm and the overall cloud 208pattern is quite disorganized. The unfavorable factors are starting 209to outweigh the favorable conditions, so the official intensity 210forecast is reduced from the previous one, a little below the model 211consensus. Extratropical transition is expected within 2 days due 212to strong shear and very cold water. A reasonable alternative 213solution provided by some of the global models is that the cyclone 214stays weak and opens up into a trough during the day on Friday. 215 216Henri is moving faster to the north, now about 13 kt. The storm 217should continue to accelerate northward tonight and northeastward 218tomorrow due to it encountering faster steering from the subtropical 219ridge. After that time, an even faster northeastward and then 220eastward motion is predicted when the cyclone becomes embedded in 221the mid-latitude flow. The guidance has trended to the left 222with the track of Henri, perhaps due to a weaker forecast 223representation of the storm. The NHC forecast is shifted in that 224direction, although remains on the right side of the guidance 225envelope. If it survives, the cyclone should become absorbed by a 226larger extratropical low by day 4 over the far North Atlantic. 227 228The latter part of this forecast, when the storm is expected to be 229post-tropical, is based on guidance provided by NOAA's Ocean 230Prediction Center. 231 232 233FORECAST POSITIONS AND MAX WINDS 234 235INIT 10/2100Z 33.9N 60.7W 35 KT 40 MPH 236 12H 11/0600Z 36.1N 60.3W 40 KT 45 MPH 237 24H 11/1800Z 39.7N 59.1W 40 KT 45 MPH 238 36H 12/0600Z 43.5N 56.5W 40 KT 45 MPH 239 48H 12/1800Z 46.8N 51.8W 40 KT 45 MPH...POST-TROP/EXTRATROP 240 72H 13/1800Z 48.5N 36.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 241 96H 14/1800Z...DISSIPATED 242 243$$ 244Forecaster Blake 245 246 247 248------------=_1441917223-44332-744 249Content-Type: text/plain; charset="US-ASCII" 250Content-Disposition: inline 251Content-Transfer-Encoding: 7BIT 252 253= = = == = = 254WTNT43 KNHC 110232 255TCDAT3 256 257TROPICAL STORM HENRI DISCUSSION NUMBER 9 258NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015 2591100 PM AST THU SEP 10 2015 260 261Henri has changed little in organization during the past several 262hours. The system continues to have some characteristics of a 263subtropical cyclone, with the convective banding and strongest 264winds well away from the center in the northeastern semicircle. 265The initial intensity remains 35 kt, as there has been no new 266scatterometer data from the area where the strongest winds are 267likely occurring. 268 269The initial motion is northward or 005/12. Henri should accelerate 270and turn to the northeast during the next 48 hours as it enters the 271mid-latitude westerlies. After that time, a quick eastward motion 272is expected until the cyclone dissipates. The new track forecast 273is an update of the previous forecast and is just to the right of 274the various consensus models. 275 276The vertical wind shear over Henri is diminishing, so there is a 277chance that the system could intensify a little before reaching cold 278water north of the Gulf Stream in about 18 hours. After that, the 279system should begin extratropical transition as it merges with a 280frontal system, and this process is expected to be complete in about 28136 hours. The cyclone is likely to be absorbed by a larger 282extratropical system between 72-96 hours. An alternative scenario 283is that Henri could degenerate to a trough between 24-72 hours as 284indicated by several of the global models. 285 286The latter part of this forecast, when the storm is expected to be 287post-tropical, is based on guidance provided by NOAA's Ocean 288Prediction Center. 289 290 291FORECAST POSITIONS AND MAX WINDS 292 293INIT 11/0300Z 34.8N 60.7W 35 KT 40 MPH 294 12H 11/1200Z 37.5N 60.1W 40 KT 45 MPH 295 24H 12/0000Z 41.2N 58.0W 40 KT 45 MPH 296 36H 12/1200Z 44.9N 54.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 297 48H 13/0000Z 47.6N 48.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 298 72H 14/0000Z 48.0N 33.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 299 96H 15/0000Z...DISSIPATED 300 301$$ 302Forecaster Beven 303 304 305 306------------=_1441938766-44332-1073 307Content-Type: text/plain; charset="US-ASCII" 308Content-Disposition: inline 309Content-Transfer-Encoding: 7BIT 310 311= = = == = = 312WTNT43 KNHC 110840 313TCDAT3 314 315TROPICAL STORM HENRI DISCUSSION NUMBER 10 316NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015 317500 AM AST FRI SEP 11 2015 318 319Overall, Henri's cloud pattern has become slightly better organized 320since the last advisory. While nearly all of the cyclone's deep 321convection is still located well to the northeast of the center, a 322relatively new convective burst over this area has grown in coverage 323and cloud tops have cooled. Subjective Dvorak classifications 324remain below tropical storm strength, but the initial intensity held 325at 35 kt due to the cyclone's increasing forward speed and somewhat 326improved satellite presentation. 327 328Southerly shear appears to be diminishing over the cyclone, as has 329been forecast by the large-scale models. The lower shear could 330allow for some additional intensification to take place during the 331next 12 hours or so while it remains over warm-enough waters. 332However, the continued presence of dry air in the near-storm 333environment and Henri's disorganized appearance suggest that any 334intensification should be negligible. After the cyclone crosses the 335northern wall of the Gulf Stream in less than 18 hours, 336substantially lower sea surface temperatures and increasingly stable 337air should induce weakening soon after that. A plausible alternate 338scenario, presented by some of the global models, is that Henri 339could degenerate into a trough later today. The cyclone or its 340remnants are forecast to undergo extratropical transition in about 34136 hours, with the system likely to be absorbed by a larger 342extratropical cyclone by 72 hours. The new intensity forecast is 343very similar to the previous one. 344 345The initial motion estimate is 010/14. Henri is expected to 346accelerate north-northeastward and then northeastward during the 347next day or so as it encounters the fast-paced flow ahead of a deep 348longwave trough digging into eastern North America and the western 349Atlantic. The post-tropical cyclone or its remnants should then turn 350east-northeastward over the north Atlantic. The new track forecast 351is adjusted to the left of the previous forecast and lies on the 352right side of the guidance envelope. 353 354The latter part of this forecast, when the storm is expected to be 355post-tropical, is partially based on guidance provided by NOAA's 356Ocean Prediction Center. 357 358 359FORECAST POSITIONS AND MAX WINDS 360 361INIT 11/0900Z 36.2N 60.3W 35 KT 40 MPH 362 12H 11/1800Z 39.0N 59.3W 40 KT 45 MPH 363 24H 12/0600Z 43.0N 56.4W 40 KT 45 MPH 364 36H 12/1800Z 46.5N 52.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 365 48H 13/0600Z 48.9N 45.9W 35 KT 40 MPH...POST-TROP/EXTRATROP 366 72H 14/0600Z...ABSORBED 367 368$$ 369Forecaster Kimberlain 370 371 372 373------------=_1441960850-44332-1203 374Content-Type: text/plain; charset="US-ASCII" 375Content-Disposition: inline 376Content-Transfer-Encoding: 7BIT 377 378= = = == = = 379WTNT43 KNHC 111456 380TCDAT3 381 382TROPICAL STORM HENRI DISCUSSION NUMBER 11 383NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015 3841100 AM AST FRI SEP 11 2015 385 386Visible satellite images indicate that the surface circulation of 387Henri has become rather distorted this morning. Multiple low-level 388swirls can be seen in the circulation that is elongated from 389southeast to northwest, with some suggestion that the cyclone may no 390longer be closed in the northwestern quadrant. The intensity is 391being held at 35 kt in agreement with the satellite estimate from 392TAFB. 393 394Although shear is somewhat lower over the cyclone, it appears that 395the low-level structure is too poor to take advantage of the more 396favorable environment. The intensity forecast has been lowered 397a little to reflect the less conducive conditions. The cyclone or 398its remnants are forecast to undergo extratropical transition in 399about 24 hours while moving over colder water with high shear, 400and the system is likely to be absorbed by a larger extratropical 401cyclone by 72 hours. An alternate scenario, one that is becoming 402more likely, is that Henri could degenerate into a trough later 403today. 404 405The initial motion estimate is 020/17. Henri is expected to 406accelerate north-northeastward and then northeastward during the 407next day or so as it encounters increasing flow ahead of a deep 408longwave trough digging into eastern North America and the western 409Atlantic. The post-tropical cyclone or its remnants should then 410turn east-northeastward over the north Atlantic. The new track 411forecast is very similar to the previous one and near or on the 412right side of the model consensus. 413 414FORECAST POSITIONS AND MAX WINDS 415 416INIT 11/1500Z 38.0N 59.4W 35 KT 40 MPH 417 12H 12/0000Z 41.0N 57.7W 35 KT 40 MPH 418 24H 12/1200Z 44.9N 54.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 419 36H 13/0000Z 48.0N 48.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 420 48H 13/1200Z 50.0N 42.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 421 72H 14/1200Z...DISSIPATED 422 423$$ 424Forecaster Blake 425 426 427 428------------=_1441983374-44332-1310 429Content-Type: text/plain; charset="US-ASCII" 430Content-Disposition: inline 431Content-Transfer-Encoding: 7BIT 432 433= = = == = = 434