Home › discussion
 

Keywords :   


Tag: discussion

Tropical Storm Hilda Forecast Discussion Number 4

2021-07-31 16:49:43| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Sat Jul 31 2021 029 WTPZ43 KNHC 311449 TCDEP3 Tropical Storm Hilda Discussion Number 4 NWS National Hurricane Center Miami FL EP082021 800 AM PDT Sat Jul 31 2021 Hilda is strengthening quickly this morning. Satellite images show an eye feature trying to form, and convection has deepened and become increasingly symmetric around the center. The latest Dvorak estimates supported raising the initial intensity to 55 kt at 12Z, and since Hilda continues to organize, the initial intensity is set a little higher at 60 kt for this advisory. This makes Hilda just below hurricane strength. The current favorable environmental conditions of low wind shear, high amounts of moisture, and warm SSTs should continue to allow Hilda to intensify during the next day or so. In addition, given that Hilda now has a tight inner core, rapid intensification (RI) is a decent possibility, and the SHIPS RI index now shows a 30 percent chance of that occurring during the next 24 hours. In a couple of days, however, decreasing moisture and progressively cooler SSTs should end the strengthening trend and gradually cause weakening during the remainder of the forecast period. The NHC intensity forecast is above than the previous one in the short term and it lies at the high end of the model guidance. The long term forecast is largely similar to the previous one and lies near the middle of the guidance envelope. Hilda is moving west-northwestward at 11 kt. A subtropical ridge should keep the storm on a general west-northwest heading during the next several days, but there could be some interaction with Tropical Depression Nine-E to the west and a low pressure area to the east that could cause slow downs and wobbles in the future track. There is a fair amount of spread among the models, especially at the longer range forecast times, but the latest consensus models are right on top of the previous track. Therefore, the NHC track forecast is largely just an update of the previous one. FORECAST POSITIONS AND MAX WINDS INIT 31/1500Z 13.7N 116.7W 60 KT 70 MPH 12H 01/0000Z 14.0N 118.2W 70 KT 80 MPH 24H 01/1200Z 14.4N 119.9W 85 KT 100 MPH 36H 02/0000Z 15.0N 121.5W 85 KT 100 MPH 48H 02/1200Z 15.5N 122.9W 85 KT 100 MPH 60H 03/0000Z 16.1N 124.3W 80 KT 90 MPH 72H 03/1200Z 16.9N 125.7W 70 KT 80 MPH 96H 04/1200Z 18.5N 128.6W 55 KT 65 MPH 120H 05/1200Z 19.3N 132.6W 45 KT 50 MPH $$ Forecaster Cangialosi

Tags: number discussion storm tropical

 

Tropical Depression Nine-E Forecast Discussion Number 4

2021-07-31 16:47:12| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Sat Jul 31 2021 798 WTPZ44 KNHC 311447 TCDEP4 Tropical Depression Nine-E Discussion Number 4 NWS National Hurricane Center Miami FL EP092021 800 AM PDT Sat Jul 31 2021 The depression has become increasingly elongated west-to-east since the previous advisory. Although deep convection has increased somewhat near the center, with cloud tops now colder than -70C, the convection isn't organized very well. The initial intensity is being maintained at 25 kt until new ASCAT data arrives this afternoon. The initial motion estimate is 270/04 kt. The latest NHC track guidance is in decent agreement on the depression moving in a slow westward direction for the next 24 hours or so, followed by a west-northwestward motion as the ridge to north of the cyclone weakens slightly. By around 72 hours, some binary interaction between the depression and rapidly strengthening Tropical Storm Hilda, located about 650 nmi to the east, is expected. However, the degree of interaction varies widely among the models. The GFS is the most extreme and takes the depression northward on days 4 and 5, with the ECMWF being the weakest, showing little if any interaction and keeps the cyclone moving generally westward through 120 h; the other global and regional models lie somewhere in between these two extremes. For now, the new official NHC track forecast was only nudged slightly northward, and lies inside the southern edge of the guidance envelope near the TVCE consensus model. The depression's future intensity and existence depends heavily on the track over the next 5 days. A more westward motion would keep the cyclone over warmer water and in a better upper-level flow regime. In contrast, a sharp northward motion, as per the GFS solution, would place the system over colder water and within strong vertical wind shear. Another negative factor is the effect of intensifying Hilda to the east, which has started to draw in the southerly/southwesterly cross-equatorial inflow away from TD-9E. This deflection of the low-level flow eastward away from the depression could result in the cyclone's cyclone getting stretched out/elongated east-to-west even further, which would induce weakening or even dissipation of the cyclone. For now, the previous intensity forecast is being maintained for this advisory until the track model guidance comes into better agreement, and the interactive effects of Tropical Storm Hilda become clearer. FORECAST POSITIONS AND MAX WINDS INIT 31/1500Z 12.1N 127.6W 25 KT 30 MPH 12H 01/0000Z 12.1N 128.2W 25 KT 30 MPH 24H 01/1200Z 12.1N 129.2W 30 KT 35 MPH 36H 02/0000Z 12.3N 130.7W 30 KT 35 MPH 48H 02/1200Z 12.5N 132.3W 35 KT 40 MPH 60H 03/0000Z 12.8N 133.7W 35 KT 40 MPH 72H 03/1200Z 13.1N 135.0W 40 KT 45 MPH 96H 04/1200Z 13.8N 137.2W 45 KT 50 MPH 120H 05/1200Z 15.5N 139.9W 45 KT 50 MPH $$ Forecaster Stewart

Tags: number discussion tropical depression

 
 

Tropical Storm Hilda Forecast Discussion Number 3

2021-07-31 10:36:34| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Sat Jul 31 2021 000 WTPZ43 KNHC 310836 TCDEP3 Tropical Storm Hilda Discussion Number 3 NWS National Hurricane Center Miami FL EP082021 200 AM PDT Sat Jul 31 2021 A prominent convective band now wraps about halfway around the southeast to west side of Hilda's center, and another band is taking shape to the north of the center. With the improved organization, Dvorak estimates increased to a consensus T3.0/45 kt from TAFB and SAB, and a 0520 UTC ASCAT-B pass confirmed that indeed maximum winds are about 45 kt. This is being set as Hilda's initial intensity, although it could be a little conservative since objective ADT estimates have trended higher than that since 0600 UTC. A mid-tropospheric ridge currently extends from northern Mexico westward across the Baja California peninsula to about 120W and is steering Hilda west-northwestward at 290/12 kt. Although this ridge is expected to build westward and keep Hilda on a west-northwestward course, potential interactions with Tropical Depression Nine-E to the west and another low pressure area to the east could cause the storm to slow down over the next 3 days and oscillate a bit around that general heading. There is slightly more spread among the track models than is typical, with the HWRF a notable southern outlier and the GFS and HMON models having some of the faster solutions due to greater interaction with T.D. Nine-E. That being said, the overall track guidance has trended a little slower and farther south on this cycle, and the updated NHC track forecast has therefore been adjusted in that direction from the previous forecast, lying close to the TVCE multi-model consensus but not nearly as far south as the HCCA consensus aid. Hilda is currently in a light-shear regime and over sea surface temperatures of about 29 degrees Celsius, so continued strengthening is anticipated in the short term with Hilda likely to reach hurricane strength by tonight or early Sunday. However, global models are suggesting that the shear may increase out of the east during the next 24 hours, and then Hilda will be near cooler waters in 2 to 3 days. Therefore, Hilda is likely to reach its peak intensity in about 48 hours, and the NHC intensity forecast at that time is near the upper end of the guidance suite. Hilda is expected to move over even cooler waters after 48 hours, which should cause a gradual weakening trend through the end of the forecast period. FORECAST POSITIONS AND MAX WINDS INIT 31/0900Z 13.3N 115.7W 45 KT 50 MPH 12H 31/1800Z 13.6N 117.3W 55 KT 65 MPH 24H 01/0600Z 14.1N 119.1W 65 KT 75 MPH 36H 01/1800Z 14.6N 120.8W 70 KT 80 MPH 48H 02/0600Z 15.1N 122.3W 75 KT 85 MPH 60H 02/1800Z 15.7N 123.7W 70 KT 80 MPH 72H 03/0600Z 16.3N 124.8W 65 KT 75 MPH 96H 04/0600Z 17.8N 127.6W 55 KT 65 MPH 120H 05/0600Z 18.9N 131.5W 45 KT 50 MPH $$ Forecaster Berg

Tags: number discussion storm tropical

 

Tropical Depression Nine-E Forecast Discussion Number 3

2021-07-31 10:36:10| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Sat Jul 31 2021 000 WTPZ44 KNHC 310836 TCDEP4 Tropical Depression Nine-E Discussion Number 3 NWS National Hurricane Center Miami FL EP092021 200 AM PDT Sat Jul 31 2021 The depression remains poorly organized this morning. Deep convection remains limited, and recent scatterometer data show that the circulation is elongated from east to west. The initial intensity is maintained at 25 kt, which could be generous based on the latest ASCAT data. As mentioned in the previous advisory, the confidence in the track and intensity forecast for the depression is quite low due to the current lack of organization of the system, and the potential for some interaction with Tropical Storm Hilda located to its northeast. The ASCAT data was helpful in pinpointing the center location overnight, and the latest fixes indicate that the cyclone is moving just south of due west or 265/5 kt. The track guidance generally agrees on a slow west or west-southwest heading over the next 12-24 hours followed by a west or west-northwest motion through 48-60 hours. After that time, the track guidance begins to diverge with the GFS showing a binary interaction of the depression and Hilda by days 4 and 5. Most of the remainder of the guidance keeps enough separation between the systems that the depression continues generally moving westward or west-northwestward through the end of the forecast period. The NHC track forecast is once again close to the various multi-model consensus aids, and is slightly slower than the previous official forecast. Although the depression is located over warm water, moderate easterly shear and dry air entrainment have prevented strengthening since genesis occurred. Given the current poor organization of the system and the marginal environment, only slow strengthening is indicated over the next few days. Another plausible scenario is that the system fails to produce organization deep convection within the next 12 to 24 hours, and it degenerates into a broad low pressure area along the ITCZ. Given this uncertainty, the NHC intensity forecast has been lowered slightly and is in best agreement with the IVCN intensity aid. FORECAST POSITIONS AND MAX WINDS INIT 31/0900Z 12.3N 127.0W 25 KT 30 MPH 12H 31/1800Z 12.2N 127.5W 25 KT 30 MPH 24H 01/0600Z 12.1N 128.3W 30 KT 35 MPH 36H 01/1800Z 12.2N 129.6W 30 KT 35 MPH 48H 02/0600Z 12.5N 131.3W 35 KT 40 MPH 60H 02/1800Z 12.8N 132.8W 35 KT 40 MPH 72H 03/0600Z 13.1N 134.2W 40 KT 45 MPH 96H 04/0600Z 13.7N 136.5W 45 KT 50 MPH 120H 05/0600Z 14.5N 138.5W 45 KT 50 MPH $$ Forecaster Brown

Tags: number discussion tropical depression

 

Tropical Depression Nine-E Forecast Discussion Number 2

2021-07-31 04:36:33| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Fri Jul 30 2021 000 WTPZ44 KNHC 310236 TCDEP4 Tropical Depression Nine-E Discussion Number 2 NWS National Hurricane Center Miami FL EP092021 800 PM PDT Fri Jul 30 2021 The depression is struggling. Aside from a stray cell or two, the cyclone has been nearly devoid of deep convection since the diurnal convective minimum earlier this evening. AMSR data near 22Z indicated that multiple weak swirls may be embedded within the broader circulation sampled earlier today by ASCAT. The initial intensity remains 25 kt for this advisory. Confidence in the track forecast is unusually low. The initial position, and therefore also the motion estimate, is highly uncertain due to the disorganized nature of the depression. On top of that, the track guidance is in extremely poor agreement regarding even the basics of the future track of the cyclone. Hilda, located relatively close to the east (about 10 degrees) may have some impact on the depression's track during the next 5 days. In fact, the GFS explicitly forecasts that a binary interaction will occur between the two tropical cyclones. Other models like the ECMWF move both systems steadily, and mostly independently, westward. As a course of least regret, the NHC track forecast is close to the previous advisory and multi-model consensus, between those two scenarios. Large changes to the track forecast may be necessary on Saturday if the track guidance begins to converge on a single solution. Warm water and moderate shear could allow for some strengthening during the next few days, if the depression can redevelop and sustain organized convection. The NHC intensity forecast assumes that will happen to some degree and has not been substantially changed. It is also possible that dry air in the environment could continue to inhibit convection as the depression moves westward. In that case, the official intensity forecast could wind up being a little too high. The NHC intensity forecast is well within the guidance envelope, but is a touch above the latest consensus. FORECAST POSITIONS AND MAX WINDS INIT 31/0300Z 12.5N 126.2W 25 KT 30 MPH 12H 31/1200Z 12.4N 126.6W 30 KT 35 MPH 24H 01/0000Z 12.3N 127.3W 30 KT 35 MPH 36H 01/1200Z 12.4N 128.4W 35 KT 40 MPH 48H 02/0000Z 12.7N 130.0W 35 KT 40 MPH 60H 02/1200Z 13.1N 131.6W 35 KT 40 MPH 72H 03/0000Z 13.4N 133.0W 40 KT 45 MPH 96H 04/0000Z 13.8N 135.9W 45 KT 50 MPH 120H 05/0000Z 14.5N 138.9W 50 KT 60 MPH $$ Forecaster Zelinsky

Tags: number discussion tropical depression

 

Sites : [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] [96] [97] [98] [99] [100] next »