je.st
news
Tag: discussion
Tropical Storm Theta Forecast Discussion Number 10
2020-11-12 09:49:43| National Hurricane Center (Atlantic)
Issued at 900 AM GMT Thu Nov 12 2020 000 WTNT45 KNHC 120849 TCDAT5 Tropical Storm Theta Discussion Number 10 NWS National Hurricane Center Miami FL AL302020 900 AM GMT Thu Nov 12 2020 Theta currently is comprised of a large swirl of low- to mid-level clouds with no convection near the center. However, a band of convection is wrapped about three-quarters of the way around the center at a distance of about 200 n mi in the eastern semicircle and 100 n mi in the western semicircle. Overall, the cyclone has somewhat of a subtropical appearance at this time. Since there has been no data from the cyclone's core region since the last scatterometer pass, the initial intensity is held at 55 kt. The storm continued to jog a little to the left since the last advisory, but the last few satellite images suggest a more eastward motion has resumed. The initial motion is a somewhat uncertain 060/10. For the next 24 h or so, Theta is expected to continue to move east-northeastward as it rounds the north side of a mid-level ridge centered over the Cabo Verde islands. An eastward to east-southeastward motion is expected from 24-72 h as the mid-level ridge to the south weakens and mid- to upper-level northerly flow moves over the cyclone. After that time, Theta or its remnants is expected to be steered northeastward in the low-level flow to the southeast of a deep-layer mid-latitude cyclone over the northeastern Atlantic. The new forecast track is adjusted north of the previous track based on the initial position and motion, and it lies near the various consensus models. Theta is forecast to change little in intensity during the next 36 h or so as it moves into the light shear area near an upper-level trough axis. After that time, the trough moves south of the cyclone, and strong northerly vertical shear should occur along with the entrainment of stable air. This combination should cause Theta to quickly weaken, and the intensity forecast calls for the system to decay to a remnant low pressure area by 96 h. The new intensity forecast has only minor adjustments from the old forecast, and it lies a little above the intensity consensus. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 31.7N 30.2W 55 KT 65 MPH 12H 12/1800Z 32.0N 28.5W 55 KT 65 MPH 24H 13/0600Z 32.3N 26.2W 55 KT 65 MPH 36H 13/1800Z 32.3N 24.0W 55 KT 65 MPH 48H 14/0600Z 32.0N 22.1W 50 KT 60 MPH 60H 14/1800Z 31.7N 20.8W 40 KT 45 MPH 72H 15/0600Z 31.6N 20.1W 35 KT 40 MPH 96H 16/0600Z 33.0N 19.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 17/0600Z 37.0N 18.0W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Beven
Tags: number
discussion
storm
tropical
Tropical Storm Eta Forecast Discussion Number 47
2020-11-12 03:46:12| National Hurricane Center (Atlantic)
Issued at 1000 PM EST Wed Nov 11 2020 000 WTNT44 KNHC 120246 TCDAT4 Tropical Storm Eta Discussion Number 47 NWS National Hurricane Center Miami FL AL292020 1000 PM EST Wed Nov 11 2020 Deep convection intensified over the northern portion of the circulation of Eta over the past few hours, however the overall cloud pattern has not become better organized this evening. Adjusted flight-level and SFMR-observed surface winds from an Air Force Reserve Hurricane Hunter aircraft indicate that the maximum winds are near 55 kt, with the central pressure holding about steady for now. Since the storm will be moving over progressively cooler waters, with strong west-southwesterly shear and some incursions of drier air, gradual weakening is likely up to landfall tomorrow morning. A more rapid weakening is likely after the center crosses the coast tomorrow. The dynamical guidance does not indicate significant restrengthening after Eta emerges into the Atlantic within 24 hours, although some baroclinic forcing could allow the system to maintain its intensity for awhile. The cyclone is likely to be absorbed by a frontal zone in 60-72 hours if not sooner. Center fixes indicate that the motion continues to be just a little to the east of due north, or 010/10 kt. A slight turn toward the right is expected soon, and over the next couple of days Eta should move north-northeastward to northeastward, ahead of a broad mid-level trough, until dissipation. The official track forecast follows the general trajectory of the simple and corrected dynamical model consensus, but is somewhat slower than the consensus guidance in deference to the latest GFS prediction. Key Messages: 1. There is a danger of life-threatening storm surge along portions of the Florida Gulf Coast from Bonita Beach to the Suwannee River, including Tampa Bay and Charlotte Harbor. Residents in this area should follow any advice given by local officials. 2. Tropical-storm-force winds are expected tonight and early Thursday along portions of the Florida Gulf Coast from Bonita Beach to the Suwanee River, and are possible tonight on Thursday from the Suwannee River to the Aucilla River. Interests elsewhere along the Florida Gulf Coast should monitor the progress of Eta. 3. Heavy rainfall from Eta will continue to spread northward across West and Central Florida through Thursday. Additional flash and urban flooding will be possible in South Florida through Thursday, especially across previously inundated areas. Flash, urban, and isolated minor river flooding is expected across portions of West and North Florida through Thursday. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 28.3N 83.4W 55 KT 65 MPH 12H 12/1200Z 29.7N 82.4W 40 KT 45 MPH...INLAND 24H 13/0000Z 31.8N 79.8W 35 KT 40 MPH...OVER WATER 36H 13/1200Z 33.7N 76.3W 30 KT 35 MPH 48H 14/0000Z 35.5N 72.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 14/1200Z 37.0N 68.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 15/0000Z...DISSIPATED $$ Forecaster Pasch
Tags: number
discussion
storm
tropical
Tropical Storm Eta Forecast Discussion Number 46
2020-11-11 22:44:07| National Hurricane Center (Atlantic)
Issued at 400 PM EST Wed Nov 11 2020 000 WTNT44 KNHC 112143 CCA TCDAT4 Tropical Storm Eta Discussion Number 46...Corrected NWS National Hurricane Center Miami FL AL292020 400 PM EST Wed Nov 11 2020 Corrected to show dissipated at 72H. Almost as quickly as Eta regained hurricane status, it then lost it shortly thereafter. Dry air entrainment eroded most of the significant convection around the center this afternoon until a slight resurgence recently developed. However, the overall convective pattern has changed little with the bulk of the convection located primarily northeast through southeast of the center. The last recon pass through Eta showed that the central pressure had increased to 990 mb. Recent Doppler velocities of around 70 kt between 5000-6000 ft east of the center supports surface winds of about 56-58 kt, so the 1800Z intensity of 60 kt will also be kept for the 21Z advisory intensity. The initial motion estimate is northward, or 010/10 kt. Eta is expected to move between north and north-northeastward tonight as the cyclone rounds the western periphery of a deep-layer ridge to the east. The new NHC model guidance remains in excellent agreement on Eta turning northeastward after 12 hours, with the cyclone making landfall along the western coast of the northern Florida peninsula in the region from Cedar Key to Crystal River. Eta is then expected to accelerate northeastward across northern Florida as a weakening tropical cyclone, and emerge over the western Atlantic by late Thursday morning or early afternoon. By 72 hours, if not sooner, Eta is forecast to merge with a frontal system off of the southeastern United States. The new official track forecast is similar to the previous advisory track, and lies close to a blend of the consensus models TVCN, NOAA-HCCA, and FSSE. Eta will be moving over progressively cooler waters during the next 12 hours, with SSTs decreasing to less than 25 deg C just before the cyclone makes landfall along the Florida coast. The cooler waters, in conjunction with continued dry air entrainment and increasing westerly vertical wind shear, should result in at least gradual weakening until landfall occurs, followed by more rapid weakening as Eta moves over the northern Florida peninsula. Although the official forecast calls for Eta to be a tropical storm as it nears the northeast coast of Florida, a Tropical Watch or Warning are not required at this time since any tropical-storm-force will likely be occurring over water and not inland or along the coast due to Eta's poor convective structure that is expected at that time. Eta is forecast to degenerate into a remnant low by 60 hours due to even stronger wind shear, and dissipate by 72 hours due to frontal interaction. Key Messages: 1. There is a danger of life-threatening storm surge along portions of the Florida Gulf Coast from Bonita Beach to Suwannee River, including Tampa Bay and Charlotte Harbor. Residents in this area should follow any advice given by local officials. 2. Tropical-storm-force winds are expected this evening and tonight along portions of the Florida Gulf Coast from Bonita Beach to Suwanee River, and are possible tonight and early Thursday from Suwannee River to Aucilla River. Interests elsewhere along the Florida Gulf Coast should monitor the progress of Eta. 3. Heavy rainfall from Eta will continue to spread northward across west and central Florida through Thursday. Additional flash and urban flooding will be possible in south Florida through Thursday, especially across previously inundated areas. Flash, urban, and isolated minor river flooding are expected across portions of west and north Florida through Thursday. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 27.3N 83.6W 60 KT 70 MPH 12H 12/0600Z 28.6N 83.1W 55 KT 65 MPH 24H 12/1800Z 30.4N 81.5W 35 KT 40 MPH...INLAND 36H 13/0600Z 32.0N 78.9W 30 KT 35 MPH...OVER WATER 48H 13/1800Z 33.8N 75.2W 25 KT 30 MPH 60H 14/0600Z 36.0N 69.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 14/1800Z...DISSIPATED $$ Forecaster Stewart
Tags: number
discussion
storm
tropical
Tropical Storm Theta Forecast Discussion Number 8
2020-11-11 21:51:04| National Hurricane Center (Atlantic)
Issued at 900 PM GMT Wed Nov 11 2020 000 WTNT45 KNHC 112050 TCDAT5 Tropical Storm Theta Discussion Number 8 NWS National Hurricane Center Miami FL AL302020 900 PM GMT Wed Nov 11 2020 The deep convection associated with Theta has been trying to wrap around the cyclone's low-level center today, and the system consists of a large curved band feature with clouds tops as cold as -65 degrees C. There was no complete sampling of the cyclone's circulation by the scatterometers today. However, a partial ASCAT-C overpass this morning showed that 40-45 kt winds were occurring in the eastern semicircle. This portion of the circulation has previously been the weaker portion of Theta, which suggests some higher winds could be occurring in the western semicircle. Therefore, the initial intensity is being kept at a somewhat uncertain 50 kt. Theta appears to be holding its own in an environment of strong southwesterly shear and over relatively cool water temperatures of about 24 degrees C, within a favorable unstable atmosphere. The cyclone will be traversing over progressively cooler waters over the next couple of days, and the shear is expected to only abate slightly. These somewhat counteracting factors should either allow Theta to maintain its intensity or slowly weaken during that time. Over the weekend, the upper-level winds are expected to increase and shift out of the north, and force more stable air across the cyclone. This should cause the convection to become displaced to the south of the center and gradually dissipate. The GFS/CMC/ECMWF simulated satellite imagery all indicate that the system should degenerate to a remnant low by 96 h. The latest NHC intensity forecast is similar to the previous one, and remains near the various multimodel consensus aids. The storm is moving east-northeastward at around 11 kt, steered by mid-latitude westerlies to the north of a mid-level ridge. This steering pattern is expected to remain in place for the next couple of days. Model guidance is trending slower over the weekend, as they are indicating that the ridge will weaken at around the same time that the shear vector becomes northerly. This would cause the cyclone to slow its forward motion and turn to the right, which is now indicated in the official forecast. However, the latest NHC track remains a little north of the consensus track guidance during that time frame. By the end of the forecast period, an approaching mid-latitude trough and associated front should pick up what remains of Theta and begin to accelerate it to the northeast. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 30.5N 31.9W 50 KT 60 MPH 12H 12/0600Z 31.1N 30.2W 50 KT 60 MPH 24H 12/1800Z 31.5N 27.8W 50 KT 60 MPH 36H 13/0600Z 31.9N 25.4W 45 KT 50 MPH 48H 13/1800Z 32.1N 23.5W 45 KT 50 MPH 60H 14/0600Z 32.0N 22.3W 45 KT 50 MPH 72H 14/1800Z 31.8N 21.3W 40 KT 45 MPH 96H 15/1800Z 31.7N 19.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 16/1800Z 35.1N 18.2W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Latto
Tags: number
discussion
storm
tropical
Tropical Storm Theta Forecast Discussion Number 7
2020-11-11 15:44:29| National Hurricane Center (Atlantic)
Issued at 300 PM GMT Wed Nov 11 2020 000 WTNT45 KNHC 111444 TCDAT5 Tropical Storm Theta Discussion Number 7 NWS National Hurricane Center Miami FL AL302020 300 PM GMT Wed Nov 11 2020 Theta's center continues to be devoid of deep convection, with the convective mass located primarily to the north of the center due to strong shear. A recent partial ASCAT overpass showed a slight decrease in the winds over the eastern semicircle. However, the pass did not sample the western portion of the circulation which has previously had the strongest winds. Based on the slightly lower ASCAT values, and the assumption that the rest of the vortex has spun down slightly due to the lack of convection over the center, the initial intensity is decreased to 50 kt. Theta is moving east-northeastward at 9 kt, steered by the southern part of the mid-latitude westerlies to the north of a mid-level ridge. This steering pattern is expected to remain in place through much of the weekend. By early next week, the ridge is forecast weaken ahead of an approaching mid-latitude trough. This would cause the cyclone to slow its forward motion temporarily before it gets picked up by the trough. The latest NHC forecast is near the previous one through 72 h, and is a little slower during days 4-5 due to the slowing of the guidance. This latest forecast is very near the clustered track consensus models. Despite the strong shear and cool water temperatures, the instability aloft should continue to support deep convection for at least the next few days. The shear is forecast to lessen somewhat in a day or so, but will still be relatively strong. Since the cyclone has been weakening slowly in the current environment, it is anticipated that the pace of weakening may lessen during the next few days with the decrease in shear. Beyond that time, the upper-level winds are forecast to become more northerly, and at about the same time the instability is forecast to decrease. These factors should cause any remaining convection to dissipate, with Theta likely becoming post-tropical by day 5. The latest NHC intensity forecast was adjusted slightly downward from the previous one mainly due to the lower initial intensity and is near the IVCN and HCCA consensus model forecasts. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 29.8N 33.3W 50 KT 60 MPH 12H 12/0000Z 30.3N 31.9W 50 KT 60 MPH 24H 12/1200Z 30.7N 29.7W 45 KT 50 MPH 36H 13/0000Z 31.1N 27.3W 45 KT 50 MPH 48H 13/1200Z 31.5N 25.1W 45 KT 50 MPH 60H 14/0000Z 31.8N 23.2W 45 KT 50 MPH 72H 14/1200Z 31.9N 22.0W 40 KT 45 MPH 96H 15/1200Z 32.2N 20.6W 35 KT 40 MPH 120H 16/1200Z 34.7N 19.2W 35 KT 40 MPH...POST-TROPICAL $$ Forecaster Latto
Tags: number
discussion
storm
tropical
Sites : [128] [129] [130] [131] [132] [133] [134] [135] [136] [137] [138] [139] [140] [141] [142] [143] [144] [145] [146] [147] next »