je.st

Home › discussion

Tag: discussion

Tropical Storm Kevin Forecast Discussion Number 17

2021-08-11 16:34:56| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Wed Aug 11 2021 000 WTPZ41 KNHC 111434 TCDEP1 Tropical Storm Kevin Discussion Number 17 NWS National Hurricane Center Miami FL EP112021 800 AM PDT Wed Aug 11 2021 Shortwave infrared images show that the center of Kevin's broad circulation is exposed to the northeast of a persistent cluster of deep convection, resulting from 15-20 kt of east-northeasterly shear over the system. With Dvorak T-numbers holding steady at T3.0 from TAFB and T2.5 from SAB, the initial intensity remains 40 kt. Recent geostationary images and a 0943 UTC GCOM overpass warranted a slight adjustment to the initial position, which now makes the initial motion northwestward at 325/9 kt. A mid-tropospheric high located over northern Mexico is expected to keep Kevin on a northwestward to west-northwestward path for the next several days, which is shown by all the track models. Most differences among the models are speed related, with the ECMWF being one of the fastest models and the GFS one of the slowest. In general, the NHC track forecast is close to the consensus aids, but the initial position adjustment required a fairly noteworthy northeastward shift in the forecast track compared to the previous advisory. Kevin's center is just about ready to move over waters cooler than 26 degrees Celsius and should be over waters as cold as 21 degrees in a couple of days. Also, the shear affecting the storm is only expected to diminish gradually, and these conditions should induce imminent weakening. In line with the latest intensity guidance, Kevin is likely to weaken to a tropical depression within 24 hours and then become a remnant low in about 48 hours when it loses all of its deep convection. This scenario is shown by the GFS and ECMWF simulated satellite imagery. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 21.0N 116.8W 40 KT 45 MPH 12H 12/0000Z 22.0N 118.2W 35 KT 40 MPH 24H 12/1200Z 23.2N 120.2W 30 KT 35 MPH 36H 13/0000Z 24.4N 122.5W 25 KT 30 MPH 48H 13/1200Z 25.6N 124.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 14/0000Z 27.0N 126.9W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 14/1200Z 28.3N 128.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 15/1200Z...DISSIPATED $$ Forecaster Berg

Tags: number discussion kevin storm

Tropical Storm Linda Forecast Discussion Number 5

2021-08-11 10:49:22| Tropical Depression LIDIA

Issued at 400 AM CDT Wed Aug 11 2021

Tags: number discussion storm linda

Tropical Storm Fred Forecast Discussion Number 7

2021-08-11 10:46:52| National Hurricane Center (Atlantic)

Issued at 500 AM AST Wed Aug 11 2021 000 WTNT41 KNHC 110846 TCDAT1 Tropical Storm Fred Discussion Number 7 NWS National Hurricane Center Miami FL AL062021 500 AM AST Wed Aug 11 2021 Fred's satellite and radar presentation have changed little since it became a tropical storm yesterday evening. The system consists mainly of a circularly shaped area of deep convection with cloud tops colder than -70C on infrared images, with some rain bands trying to wrap around the center on radar images. The outer banding features have become indistinct on satellite imagery at the moment. Upper-level outflow remains well defined. Wind gusts to tropical storm force were reported at elevated sites at Cabo Rojo on the southwestern tip of Puerto Rico. The current intensity estimate is held at 35 kt, in agreement with Advanced Dvorak Technique estimates from UW-CIMSS. A west-northwestward motion appears to have resumed, at about 14 kt. The system should continue to move on this heading with a gradual decrease in forward speed, on the south side of a mid-level subtropical ridge, for the next 2-3 days. Around 72 hours, Fred should begin to turn to the right as it nears the western periphery of the ridge. During the next 3-5 days a generally northwestward track, toward a weakness in the ridge, is likely. The official forecast track is about the same as the previous one, and in good agreement with the latest TVCA and HCCA model consensus guidance. Again, users are advised that 4- and 5-day track forecasts have average errors of 175 and 200 miles, respectively. Although the vertical shear is currently low, which would normally be conducive for strengthening, the cyclone will soon begin to interact with the land mass of Hispaniola. This should cause some weakening later today and tonight. Some restrengthening should occur after the system moves away from that island. However, given the likely disruption of the circulation by the mountains, Fred may be slow to regain intensity. Moreover, an upper-level low and trough near Florida in 2-3 days could impart increasing west-southwesterly shear and limit intensification. The official intensity forecast is close to the model consensus and the LGEM guidance. As usual, there is significant uncertainty in the intensity forecast for the latter part of the period. KEY MESSAGES: 1. Tropical storm conditions are expected to begin in portions of the Dominican Republic this morning. Tropical storm conditions are possible in northern Haiti and the southeastern Bahamas by late today. 2. Heavy rainfall could lead to flash, urban, and small stream flooding, along with possible rapid river rises and the potential for mudslides across the U.S. Virgin Islands, Puerto Rico, and the Dominican Republic. The greatest threat for flooding impacts will be across eastern and southern Puerto Rico. 3. There is a risk of wind and rainfall impacts elsewhere in portions of Hispaniola, the Bahamas, and Cuba during the next few days, although the forecast is more uncertain than usual since Fred is forecast to interact with Hispaniola today. Interests in these areas should monitor Fred's progress and updates to the forecast. 4. There is a risk of wind and rainfall impacts in Florida beginning Friday in the Keys and spreading northward through portions of the Peninsula and the Panhandle this weekend. However, it is too soon to determine the exact timing, location, and magnitude of any potential impacts. Interests throughout Florida should monitor Fred's progress and check updates to the forecast. FORECAST POSITIONS AND MAX WINDS INIT 11/0900Z 18.0N 68.2W 35 KT 40 MPH 12H 11/1800Z 19.0N 70.2W 30 KT 35 MPH...INLAND 24H 12/0600Z 20.1N 72.5W 30 KT 35 MPH...OVER WATER 36H 12/1800Z 21.1N 74.7W 35 KT 40 MPH 48H 13/0600Z 22.1N 77.0W 35 KT 40 MPH 60H 13/1800Z 23.0N 79.0W 35 KT 40 MPH 72H 14/0600Z 24.1N 80.7W 40 KT 45 MPH 96H 15/0600Z 27.0N 83.0W 45 KT 50 MPH 120H 16/0600Z 29.5N 85.0W 55 KT 65 MPH $$ Forecaster Pasch

Tags: number discussion storm fred

Tropical Storm Kevin Forecast Discussion Number 15

2021-08-11 05:25:48| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Tue Aug 10 2021 000 WTPZ41 KNHC 110325 CCA TCDEP1 Tropical Storm Kevin Discussion Number 15...Corrected NWS National Hurricane Center Miami FL EP112021 800 PM PDT Tue Aug 10 2021 Corrected direction of motion in the second paragraph. Tracking the center of Kevin this evening has been a challenge, as multiple low-level swirls appear to be rotating cyclonically around a broader mean circulation. The deeper convection remains mostly south of the estimated circulation center, though some cooler cloud tops did attempt to build northward, following a mesovortex seen on visible satellite imagery. Subjective Dvorak intensity estimates from SAB and TAFB at 0000 UTC were T2.5/35 kt and T3.0/45 kt, respectively, and the latest UW-CIMSS SATCON estimate was hovering between these values at 42 kt. The initial intensity is held at 45 kt for this advisory, favoring the higher intensity estimates given the earlier ASCAT data. The initial motion is estimated at 320/7 kt, attempting to follow the mean center that has several mesovorticies rotating around. A general northwest to west-northwestward motion is expected to continue over the next several days as the large cyclone is steered by a deep-layer ridge located to its northeast. The latest track guidance was a bit more poleward compared to the previous cycle, and the latest NHC track forecast has been shifted a bit more poleward in the short term, choosing to remain close to the track guidance consensus. Moderate to strong northeasterly wind shear continues to keep Kevin's deepest convection downshear in the southern semicircle of the large circulation envelope. Over the next 24 hours, Kevin will also be crossing a sharp sea-surface temperature (SST) gradient, with sub 26 C SSTs not far away to the north. As the cyclone moves over these progressively cooler waters, gradual weakening should commence. Simulated IR brightness temperature data from both the GFS and ECMWF suggest that Kevin will lose its remaining organized convection by 48-60 hours, and the latest NHC intensity forecast shows Kevin becoming a remnant low by that time. FORECAST POSITIONS AND MAX WINDS INIT 11/0300Z 19.5N 115.4W 45 KT 50 MPH 12H 11/1200Z 20.7N 116.5W 40 KT 45 MPH 24H 12/0000Z 21.9N 118.3W 35 KT 40 MPH 36H 12/1200Z 23.0N 120.3W 30 KT 35 MPH 48H 13/0000Z 24.0N 122.5W 25 KT 30 MPH 60H 13/1200Z 25.1N 124.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 14/0000Z 26.3N 126.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 15/0000Z 28.4N 130.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 16/0000Z...DISSIPATED $$ Forecaster Papin/Stewart

Tags: number discussion kevin storm