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Hurricane Elida Forecast Discussion Number 14

2020-08-12 10:34:56| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Wed Aug 12 2020 000 WTPZ44 KNHC 120834 TCDEP4 Hurricane Elida Discussion Number 14 NWS National Hurricane Center Miami FL EP092020 200 AM PDT Wed Aug 12 2020 Satellite imagery over the past several hours shows that the deep convection associated with Elida has been shrinking in coverage, while earlier microwave data revealed that the low-level center is on the southern edge of the convection. All of the available Dvorak data-T numbers have been on the decline tonight, and there remains a large spread in the Dvorak CI numbers, ranging from about 50-75 kt. The initial advisory intensity has been set to 65 kt, which is essentially a blend of the TAFB and SAB CI numbers along with the latest UW/CIMSS SATCON estimate. Elida is now moving over water temperatures below 24C, and the cyclone is heading towards even cooler waters. In addition, the cyclone's surrounding environment is expected to become increasingly drier and more stable over the next 24 h. These factors should cause Elida to rapidly weaken over the next day or so, with the cyclone expected to weaken to a tropical storm later today. After 24 h, vertical wind shear is forecast to increase, which should help to dissipate any remaining deep convection associated with Elida around that time. The latest NHC intensity forecast is very close to the various consensus aids through the period of rapid weakening, and is similar to the previous forecast. Elida is now moving west-northwestward at about 11 kt. This general motion is expected to continue through today, as the cyclone moves around the southwestern portion of a mid-level ridge centered over the southwestern United States. By tonight, the western portion of the ridge is forecast to weaken, which should allow Elida to turn northwestward with some additional slowing of its forward speed. This new motion should continue until the system becomes a remnant low. The latest NHC forecast is little changed from the previous and is near the well-clustered track guidance. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 23.0N 117.7W 65 KT 75 MPH 12H 12/1800Z 23.7N 119.1W 50 KT 60 MPH 24H 13/0600Z 24.8N 120.3W 35 KT 40 MPH 36H 13/1800Z 25.9N 121.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 14/0600Z 27.2N 122.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 14/1800Z 28.5N 123.1W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 15/0600Z...DISSIPATED $$ Forecaster Latto

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Hurricane Elida Forecast Discussion Number 13

2020-08-12 04:36:21| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Tue Aug 11 2020 000 WTPZ44 KNHC 120236 TCDEP4 Hurricane Elida Discussion Number 13 NWS National Hurricane Center Miami FL EP092020 800 PM PDT Tue Aug 11 2020 Recent infrared satellite imagery shows that the cloud tops associated with the tropical cyclone have gradually warmed, especially over the southwestern portion of the circulation. A timely 2357 UTC SSMIS microwave overpass indicated that the southern portion of the eye has eroded and that the low-level center is located a little south of recent position estimates using visible satellite imagery. The latest subjective and objective Dvorak satellite estimates range from about 60-90 kt. The advisory intensity has been set at 75 kt, which is in best agreement with the latest UW/CIMSS SATCON estimate, and is a blend of the of the latest Dvorak CI numbers from TAFB and SAB. The cyclone has already crossed the 26C isotherm and is headed toward significantly cooler waters. In addition, the vertical wind shear is predicted to increase slightly over the next 12-24 hours. These negative environmental factors should lead to rapid weakening over the next 24 to 36 hours. Elida is forecast to weaken to a tropical storm on Wednesday, and it should degenerate into a post-tropical cyclone on Thursday when it loses its deep convection. The new NHC intensity forecast essentially follows the trend of the previous advisory, and is in good agreement with the various consensus aids. Elida continues moving west-northwestward at about 13 kt. The cyclone should remain on this general heading through Wednesday as it moves around the southwestern portion of a mid-level ridge centered over the southwestern United States. After that time, a trough located well west of southern California is expected to weaken the western portion of the ridge, causing Elida to slow down and turn northwestward. The dynamical model guidance is in good agreement on this scenario, and no significant change to the previous forecast was required. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 22.5N 116.5W 75 KT 85 MPH 12H 12/1200Z 23.2N 118.2W 65 KT 75 MPH 24H 13/0000Z 24.1N 119.7W 50 KT 60 MPH 36H 13/1200Z 25.1N 120.8W 35 KT 40 MPH...POST-TROPICAL 48H 14/0000Z 26.2N 121.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 14/1200Z 27.5N 122.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 15/0000Z...DISSIPATED $$ Forecaster Brown

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Tropical Depression Eleven Forecast Discussion Number 2

2020-08-12 04:33:49| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Tue Aug 11 2020 913 WTNT41 KNHC 120233 TCDAT1 Tropical Depression Eleven Discussion Number 2 NWS National Hurricane Center Miami FL AL112020 1100 PM AST Tue Aug 11 2020 After weakening in the early evening hours, deep convection has returned to the western semicircle of the tropical cyclone. While this is quite a strong burst, it appears that the convective pattern is indicative of the shear it is encountering, rather than any strengthening. This is confirmed by ASCAT-B data from a few hours ago, which supported maintaining an initial wind speed of 30 kt. By this time tomorrow, the depression is forecast to become a tropical storm due to decreasing vertical wind shear, and this environmental change should also keep some of the surrounding mid-level dry air from mixing near the center. Gradually warming SSTs and relatively low shear conditions suggest further intensification through about 2-3 days. Thereafter, increasing southwesterly shear while the small cyclone moves through fairly dry air aloft is forecast to cause a weakening trend, and it wouldn't be surprising if the cyclone even degenerates to a trough by day 5 as it traverses the hostile environment. The new NHC wind speed prediction is near but slightly higher than the previous advisory through 60h, similar afterwards, and lies near the NOAA corrected-consensus mean. The depression continues moving westward, or 280/12 kt, to the south of a large mid-tropospheric high centered over the central Atlantic. A break developing in the ridge should steer the depression more west-northwestward from 36 hours until the end of the forecast period. For a second advisory, the track models are in remarkably good agreement, and the forecast is near or northeast of the model consensus. The HWRF solution that takes the cyclone near the Leeward Islands is considering less likely at this time, hence the official forecast is shaded toward the other model solutions. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 12.0N 41.5W 30 KT 35 MPH 12H 12/1200Z 12.3N 43.4W 30 KT 35 MPH 24H 13/0000Z 12.8N 45.9W 35 KT 40 MPH 36H 13/1200Z 13.5N 48.3W 40 KT 45 MPH 48H 14/0000Z 14.5N 50.8W 45 KT 50 MPH 60H 14/1200Z 15.7N 53.3W 50 KT 60 MPH 72H 15/0000Z 17.0N 55.7W 45 KT 50 MPH 96H 16/0000Z 19.5N 60.5W 40 KT 45 MPH 120H 17/0000Z 22.0N 65.0W 35 KT 40 MPH $$ Forecaster Blake

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Hurricane Elida Forecast Discussion Number 12

2020-08-11 22:35:48| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Tue Aug 11 2020 000 WTPZ44 KNHC 112035 TCDEP4 Hurricane Elida Discussion Number 12 NWS National Hurricane Center Miami FL EP092020 200 PM PDT Tue Aug 11 2020 Elida has not changed significantly in organization since the last advisory, as the storm continues to have a small cloud-filled eye inside a symmetric central dense overcast. Various objective and subjective satellite intensity estimates are slightly lower than the previous advisory, but they have not decreased enough to justify lowering the initial intensity yet. The initial motion is west-northwestward or 300/13 kt. The track guidance is in good agreement than Elida should move west- northwestward for the next 36 h or so. After that, the guidance is in better agreement that Elida should turn northwestward with a decrease in forward speed due to interaction with an upper-level low off of the coast of California. There is little change to the forecast track, which lies near the various consensus models, from the previous advisory. Elida is moving toward colder sea surface temperatures, with the center forecast to be over 23C water in 24 h and 22C in 48 h. This should lead to rapid weakening beginning in the next 6-12 h, with the global models forecasting the system to weaken to a trough by 72 h. The new intensity forecast follows the trend of the guidance and calls for Elida to drop below hurricane strength in just over 24 h, degenerate to a remnant low by 48 h, and dissipate by 72 h. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 22.1N 115.4W 85 KT 100 MPH 12H 12/0600Z 22.7N 117.2W 75 KT 85 MPH 24H 12/1800Z 23.6N 119.0W 65 KT 75 MPH 36H 13/0600Z 24.6N 120.3W 45 KT 50 MPH 48H 13/1800Z 25.5N 121.1W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 14/0600Z 26.7N 122.1W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 14/1800Z...DISSIPATED $$ Forecaster Beven

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Tropical Depression Eleven Forecast Discussion Number 1

2020-08-11 22:32:51| National Hurricane Center (Atlantic)

Issued at 500 PM AST Tue Aug 11 2020 000 WTNT41 KNHC 112032 TCDAT1 Tropical Depression Eleven Discussion Number 1 NWS National Hurricane Center Miami FL AL112020 500 PM AST Tue Aug 11 2020 Visible satellite imagery and ASCAT-C data from earlier in the day have shown that the area of low pressure NHC has been monitoring over the tropical Atlantic has developed a less-elongated circulation with a well-defined center. For the most part, deep convection has persisted with the system since about this time yesterday, save a brief period of warming cloud tops this morning. The low now meets the criteria of a tropical cyclone, and advisories have been initiated on Tropical Depression Eleven with 30-kt winds, in line with the latest Dvorak Current Intensity numbers from TAFB and SAB. The depression is moving westward, or 280/14 kt, to the south of a large mid-tropospheric high centered over the central Atlantic. This pattern is expected to evolve rather quickly, with a break developing in the ridge over the central Atlantic by 48 hours. This change should allow the depression to begin making more poleward progress, moving west-northwestward from 36 hours until the end of the forecast period. The track models are in good agreement on this scenario, as well as the system's forward speed, and bring the center of the cyclone near or just to the north of the northern Leeward Islands in 4-5 days. This first NHC forecast lies just to the north of the multi-model consensus cluster through day 3, out of respect for the northern-lying ECMWF model, and then is close to HCCA on days 4 and 5. Conventional satellite imagery and Saharan Air Layer analyses suggest that the center of the depression is being shielded from much drier air to its north and west. However, as has been the case for a few days, at least 15 kt of easterly shear has been pushing deep convection to the western side of the circulation. This shear is expected to decrease over the next day or two, which should allow for gradual strengthening to begin by 36 hours, and a peak in the cyclone's intensity should occur in about 3 days. For this period, the NHC intensity forecast is a little above HCCA and the IVCN intensity consensus. After that time, westerly or southwesterly shear is forecast to develop and increase to 20-30 kt by days 4 and 5, which is likely to induce significant weakening. In fact, it's notable that the conditions become hostile enough that the global models are showing the system opening up into a trough near the northern Leeward Islands by day 5, which is a plausible alternate scenario. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 11.7N 40.0W 30 KT 35 MPH 12H 12/0600Z 12.0N 42.1W 30 KT 35 MPH 24H 12/1800Z 12.4N 44.5W 30 KT 35 MPH 36H 13/0600Z 13.0N 46.9W 35 KT 40 MPH 48H 13/1800Z 13.9N 49.4W 40 KT 45 MPH 60H 14/0600Z 15.1N 51.8W 45 KT 50 MPH 72H 14/1800Z 16.4N 54.3W 45 KT 50 MPH 96H 15/1800Z 18.5N 59.5W 40 KT 45 MPH 120H 16/1800Z 21.0N 64.0W 35 KT 40 MPH $$ Forecaster Berg

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