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Tropical Storm Paulette Forecast Discussion Number 5
2020-09-08 04:32:59| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Mon Sep 07 2020 000 WTNT42 KNHC 080232 TCDAT2 Tropical Storm Paulette Discussion Number 5 NWS National Hurricane Center Miami FL AL172020 1100 PM AST Mon Sep 07 2020 Satellite images show that Paulette continues to become better organized, with a more symmetric presentation and very deep convection near or just north of the center. The initial wind speed is increased to 40 kt, a little higher than recent subjective Dvorak estimates, but close to the objective estimates and the UW-CIMSS satellite consensus. Further strengthening is expected during the next day or so while the storm remains in a warm SST and low-to-moderate shear environment. By midweek, some weakening is forecast due to an increase in shear from an enhanced mid-oceanic upper-level trough. There's a fair amount of uncertainty on how quickly the tropical cyclone moves across the trough axis, which would then allow Paulette to find an area of lighter shear, plus very warm water, by the end of the forecast period. The intensity forecast is slightly higher in the short-term, and lower in the day-4 period just before the environment is forecast to improve. Paulette appears to be moving slowly north-northwestward this evening. A mid-level ridge is likely to build over the western and central North Atlantic in a day or two, and this pattern should cause Paulette to move faster toward the northwest tomorrow, and west-northwestward or westward through late week. A turn back toward the west-northwest or northwest is possible over the weekend as the cyclone reaches the western periphery of the ridge. This is not a particularly certain forecast because the track models aren't in good agreement, perhaps linked to the strength of Paulette, and there is significant spread in the various ensemble guidance. With no clear trends to rely on, and since the new model consensus came in very close to the previous NHC forecast, the new NHC track prediction is basically unchanged from the previous one. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 17.8N 42.5W 40 KT 45 MPH 12H 08/1200Z 18.4N 42.9W 45 KT 50 MPH 24H 09/0000Z 19.2N 44.1W 50 KT 60 MPH 36H 09/1200Z 19.9N 45.9W 55 KT 65 MPH 48H 10/0000Z 20.5N 47.9W 55 KT 65 MPH 60H 10/1200Z 20.9N 49.9W 50 KT 60 MPH 72H 11/0000Z 21.3N 51.8W 50 KT 60 MPH 96H 12/0000Z 22.5N 55.0W 45 KT 50 MPH 120H 13/0000Z 25.0N 58.0W 50 KT 60 MPH $$ Forecaster Blake
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Tropical Storm Rene Forecast Discussion Number 4
2020-09-08 04:32:00| National Hurricane Center (Atlantic)
Issued at 200 AM CVT Tue Sep 08 2020 000 WTNT43 KNHC 080231 TCDAT3 Tropical Storm Rene Discussion Number 4 NWS National Hurricane Center Miami FL AL182020 200 AM CVT Tue Sep 08 2020 Convection has noticeably waned during the past few hours as Rene's center moved directly over Boa Vista island between 07/2200 UTC and 08/0000 UTC. The highest observed wind speed thus far has been a 10-minute average wind of 25 kt at Sal/GVAC. Satellite intensity estimates range from 35 kt from TAFB to 30 kt from SAB. A 07/2323 UTC ASCAT-B overpass indicated peak winds of 27 kt, but land obscuration likely has resulted in some missed higher wind speeds. For now, the intensity will remain at 35 kt. The initial motion is 280/12 kt. A westward motion is expected today, followed by a west-northwestward motion through Thursday as Rene rounds the southwestern periphery of a deep-layer subtropical ridge. On days 4 ad 5, the cyclone is forecast to move more slowly northwestward to north-northwestward through a weakness in the aforementioned ridge. The track guidance appears to have stabilized on the latest set of model runs and, thus, the new NHC forecast track is very similar to the previous advisory track, and lies close to a blend of the TVCA and NOAA-HCCA consensus track models. The intensity forecast was held steady for the next 12 h or so until Rene clears the negative influence of the mountainous Cabo Verde Islands. It's possible that Rene could even weaken by the time it passes the western Cabo Verde Islands. Thereafter, however, environmental conditions appear conducive for the cyclone to gradually strengthen, becoming a hurricane on day 3. By days 4 and 5, an increase in southwesterly vertical wind shear is expected to induce a weakening trend. The new NHC intensity forecast is similar to a blend of the IVCN and the HCCA intensity consensus models, and the GFS model. Key Messages: 1. Rene is expected to produce tropical storm conditions across portions of the Cabo Verde Islands this morning and afternoon. A Tropical Storm Warning is in effect for those islands. 2. Rene will bring locally heavy rainfall to portions of the Cabo Verde Islands through this afternoon. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 16.2N 23.5W 35 KT 40 MPH 12H 08/1200Z 16.5N 25.5W 35 KT 40 MPH 24H 09/0000Z 16.8N 28.2W 45 KT 50 MPH 36H 09/1200Z 17.3N 30.9W 50 KT 60 MPH 48H 10/0000Z 18.2N 33.6W 60 KT 70 MPH 60H 10/1200Z 19.1N 36.1W 65 KT 75 MPH 72H 11/0000Z 20.2N 38.3W 70 KT 80 MPH 96H 12/0000Z 23.1N 41.9W 65 KT 75 MPH 120H 13/0000Z 27.6N 44.1W 55 KT 65 MPH $$ Forecaster Stewart
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Tropical Storm Rene Forecast Discussion Number 3
2020-09-07 22:34:55| National Hurricane Center (Atlantic)
Issued at 800 PM CVT Mon Sep 07 2020 000 WTNT43 KNHC 072034 TCDAT3 Tropical Storm Rene Discussion Number 3 NWS National Hurricane Center Miami FL AL182020 800 PM CVT Mon Sep 07 2020 The cyclone is getting better organized on its approach to the Cabo Verde Islands. Banding features are now well established over the western part of the circulation, and some smaller bands are filling in east of the center. The satellite intensity estimates currently range from 30 to 35 kt. Based on this data and the improved satellite appearance of the system, the initial intensity is raised to 35 kt, making the cyclone Tropical Storm Rene. Rene is the 17th named storm of the 2020 Atlantic hurricane season. It is also the earliest 17th named storm of any Atlantic season by 11 days. The previous record was Rita, which formed on September 18, 2005. Rene is moving west-northwestward at 10 kt, and it should continue moving in that direction with some increase in forward speed for at least the next few days while subtropical ridging builds westward to the north of the storm. Toward the end of the forecast period, a turn to the northwest is expected as Rene moves into a weakness in the ridge. The models have shifted eastward at the longer ranges, especially the ECMWF model, and the NHC forecast has been adjusted in that direction at days 3 through 5. Rene is forecast to gradually strengthen during the next few days as the storm is expected to remain over relatively warm water while moving through an environment consisting of low vertical wind shear and high amounts of moisture. An increase in southwesterly shear late this week and this weekend should end the strengthening trend and induce some weakening. The NHC intensity forecast is again an update of the previous one, and is now in line with the HCCA and IVCN consensus models. Key Messages: 1. Rene is expected to produce tropical storm conditions across portions of the Cabo Verde Islands tonight and early Tuesday. A Tropical Storm Warning is in effect for those islands. 2. Rene will bring locally heavy rainfall to portions of the Cabo Verde Islands through Tuesday morning. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 16.1N 22.3W 35 KT 40 MPH 12H 08/0600Z 16.3N 24.1W 40 KT 45 MPH 24H 08/1800Z 16.7N 26.8W 50 KT 60 MPH 36H 09/0600Z 17.2N 29.6W 55 KT 65 MPH 48H 09/1800Z 17.8N 32.3W 60 KT 70 MPH 60H 10/0600Z 18.6N 35.0W 65 KT 75 MPH 72H 10/1800Z 19.6N 37.4W 70 KT 80 MPH 96H 11/1800Z 22.1N 41.3W 70 KT 80 MPH 120H 12/1800Z 26.0N 44.0W 65 KT 75 MPH $$ Forecaster Cangialosi
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Tropical Storm Paulette Forecast Discussion Number 4
2020-09-07 22:31:22| National Hurricane Center (Atlantic)
Issued at 500 PM AST Mon Sep 07 2020 000 WTNT42 KNHC 072031 TCDAT2 Tropical Storm Paulette Discussion Number 4 NWS National Hurricane Center Miami FL AL172020 500 PM AST Mon Sep 07 2020 Recent visible imagery shows that Paulette's circulation has become better defined since this morning. There has also been some evidence of increased banding, however the tropical storm remains sheared, with deep convection occuring primarily in its northeast quadrant. Recent satellite-based intensity estimates range from just below to just above the 35-kt intensity estimate. The NHC forecast still calls for modest strengthening over the next day or two, and this seems like a good bet given the recent observed improvement of Paulette's organization and structure. Moderate shear and some surrounding dry air appear to be inhibiting factors for substantial intensification, though the HWRF is a notable outlier that forecasts Paulette to become a hurricane in about 48 h. No major changes to the official intensity forecast were required at this time, and the NHC forecast is between the IVCN and HCCA consensus aids. Paulette appears to have moved slowly toward the northwest during the past several hours. The guidance spread has increased a little, though the models all have the same general idea. For the next 12 to 24 hours, Paulette will be embedded in an area of weak steering flow, though reformations of the center closer to the convection could result in a northwest to north-northwestward motion. A mid-level ridge is forecast to build over the western and central North Atlantic in a day or two and this should cause Paulette to turn back toward the west. The NHC forecast is slightly north of the previous one and is close to the latest multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 17.5N 42.4W 35 KT 40 MPH 12H 08/0600Z 17.9N 42.7W 40 KT 45 MPH 24H 08/1800Z 18.8N 43.6W 45 KT 50 MPH 36H 09/0600Z 19.6N 45.0W 50 KT 60 MPH 48H 09/1800Z 20.3N 46.8W 50 KT 60 MPH 60H 10/0600Z 20.8N 48.8W 50 KT 60 MPH 72H 10/1800Z 21.1N 50.7W 50 KT 60 MPH 96H 11/1800Z 21.8N 53.8W 50 KT 60 MPH 120H 12/1800Z 24.0N 56.5W 50 KT 60 MPH $$ Forecaster Zelinsky
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Tropical Storm Paulette Forecast Discussion Number 3
2020-09-07 16:39:52| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Mon Sep 07 2020 000 WTNT42 KNHC 071439 TCDAT2 Tropical Storm Paulette Discussion Number 3 NWS National Hurricane Center Miami FL AL172020 1100 AM AST Mon Sep 07 2020 Visible imagery and recent ASCAT data indicate that the circulation of Paulette is quite elongated from southwest to northeast. However, the ASCAT data indicated that winds up to tropical-storm-force were present, and this was corroborated by a 35 kt Dvorak-based intensity estimate from TAFB. Paulette is the 16th named storm of the 2020 Atlantic hurricane season. It is also the earliest 16th named storm of any Atlantic season by 10 days. The previous record was Philippe, which formed on September 17, 2005. Although it is elongated, the tropical storm's structure seems to have improved over the past few hours, with convection increasing in both coverage and organization. Although moderate southerly shear and some dry environmental air appear to be limiting factors, most of the intensity guidance suggests that modest strengthening is likely for the next couple of days. Near the end of the week, the models indicate that Paulette's winds will plateau or possibly decrease. This appears to be the result of increasing southwesterly shear associated with a upper-level trough that is forecast to deepen over the central Atlantic on Thursday and Friday. The official intensity forecast remains very near the multi-model consensus. Paulette has moved very little during the past few hours, but a west-northwestward to northwestward motion is expected to resume shortly. Fluctuations in the strength of a mid-level ridge over the western and central Atlantic will likely cause Paulette's exact speed and heading to fluctuate during the next several says, but the guidance agrees that it should generally head northwestward through the end of the week. It is likely that the stronger Paulette gets, the farther north it will move since the aforementioned upper-level trough will have a greater influence on its track. The NHC track forecast is based on a blend of the previous forecast and the latest multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 17.2N 42.2W 35 KT 40 MPH 12H 08/0000Z 17.4N 42.5W 40 KT 45 MPH 24H 08/1200Z 17.9N 43.2W 40 KT 45 MPH 36H 09/0000Z 18.7N 44.4W 45 KT 50 MPH 48H 09/1200Z 19.6N 46.0W 50 KT 60 MPH 60H 10/0000Z 20.3N 48.2W 50 KT 60 MPH 72H 10/1200Z 20.7N 50.0W 50 KT 60 MPH 96H 11/1200Z 21.0N 53.0W 45 KT 50 MPH 120H 12/1200Z 23.0N 56.5W 45 KT 50 MPH $$ Forecaster Zelinsky
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