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Hurricane Eta Forecast Discussion Number 13

2020-11-03 21:45:46| National Hurricane Center (Atlantic)

Issued at 400 PM EST Tue Nov 03 2020 000 WTNT44 KNHC 032045 TCDAT4 Hurricane Eta Discussion Number 13 NWS National Hurricane Center Miami FL AL292020 400 PM EST Tue Nov 03 2020 After meandering just offshore of the coast of northeastern Nicaragua this morning, the eye of Eta began moving westward and is currently making landfall along the coast of Nicaragua about 15 n mi south of Puerto Cabezas. Visible satellite imagery has shown that the eye of Eta became larger as the hurricane completed an eyewall replacement. A blend of the earlier aircraft data and recent subjective and objective satellite intensity estimates yields an initial intensity of 120 kt. Eta remains an extremely dangerous category 4 hurricane, and is likely producing a very high storm surge and catastrophic damage. In addition, the slow-moving system is likely to produce torrential rains and inland flooding that will continue to be an extremely serious threat over the next couple of days. Once the eyewall is fully onshore, rapid weakening should begin, and Eta is forecast to weaken to a tropical storm by early Wednesday, and become a tropical depression Wednesday night. Although it appears unlikely that the surface circulation will remain intact while Eta moves over Central America, most of the global model guidance indicates that the low-level vorticity center will emerge over the northwestern Caribbean Sea within 60-72 hours. At that time, the system is forecast to interact with an upper-level trough over the northern Gulf of Mexico, and re-development later in the period appears likely with some strengthening by days 4 and 5. Due the interaction with the upper-level trough, the system is likely to have a more hybrid or subtropical structure late in the period. Eta appears to be moving westward at about 4 kt. A ridge to the north of the hurricane should steer the system westward to west- northwestward at a faster forward speed over the next couple of days. By late in the week, Eta or its remnants should turn northward, and then northeastward around the southeastern portion of the aforementioned trough. Although the 12z GFS and ECMWF models are in general agreement on the overall forecast scenario, there are large differences in how fast Eta accelerates northeastward. The NHC track forecast is near the HFIP corrected consensus model which lies between the faster GFS and slower ECMWF solutions. There is still significant spread among the various global models and the ensembles, which results in a higher than normal level of uncertainty regarding the details of the track and intensity forecast later in the period. Key Messages: 1. Catastrophic wind damage is expected during the next few hours as Eta's eyewall moves onshore along the northeastern coast of Nicaragua. 2. A catastrophic and life-threatening storm surge, along with destructive waves, are expected along portions of the northeastern coast of Nicaragua near and to the north of where the center has crossed the coast. Water levels could reach as high as 14 to 21 feet above normal tide levels in some parts of the hurricane warning area. 3. Through Friday evening, heavy rainfall from Eta will lead to catastrophic, life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Flash and river flooding is also possible across Jamaica, southeast Mexico, El Salvador, southern Haiti, and the Cayman Islands. 4. Eta is forecast to regain tropical storm strength as it moves across portions of Cuba and approaches southern Florida this weekend. While it is too soon to determine the exact timing, magnitude, and location of possible impacts from wind and rainfall, interests in Cuba, southern Florida and the Florida Keys should monitor the progress of Eta through the week. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 13.8N 83.5W 120 KT 140 MPH 12H 04/0600Z 13.8N 84.2W 75 KT 85 MPH...INLAND 24H 04/1800Z 14.1N 85.5W 40 KT 45 MPH...INLAND 36H 05/0600Z 14.7N 87.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 05/1800Z 15.4N 88.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 06/0600Z 16.3N 88.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 06/1800Z 17.0N 87.7W 30 KT 35 MPH...OVER WATER 96H 07/1800Z 20.0N 83.5W 40 KT 45 MPH 120H 08/1800Z 24.0N 80.5W 45 KT 50 MPH $$ Forecaster Brown

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Tropical Storm Odalys Forecast Discussion Number 1

2020-11-03 21:41:09| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Tue Nov 03 2020 000 WTPZ45 KNHC 032041 TCDEP5 Tropical Storm Odalys Discussion Number 1 NWS National Hurricane Center Miami FL EP202020 200 PM PDT Tue Nov 03 2020 The low pressure area well south-southwest of the southern tip of the Baja California Peninsula has become significantly better organized today. A curved band of deep convection is noted to the northwest of the low-level center, and a second weaker band is located to its southeast. Satellite-derived wind data indicate the low-level center is still somewhat broad, but it appears to have enough definition to justify starting advisories as a tropical cyclone. Recent ASCAT-B data show numerous 30+ kt wind barbs, with a couple barbs peaking at 33-34 kt in the eastern semicircle of the cyclone. Considering known under-sampling issues with this data source, the initial intensity is set at 35 kt, which is consistent with a T2.5 subjective Dvorak classification from TAFB. Thus, the system has become a tropical storm, and advisories are initiated on Tropical Storm Odalys. Weak to moderate vertical wind shear and sufficient oceanic heat content may support modest strengthening during the next 12 h or so. By 24-36 h, strong southwesterly deep-layer shear associated with an approaching shortwave trough to the northwest, along with intrusions of drier mid-level air, will induce a steady and perhaps rapid weakening trend. The system is forecast to weaken to a depression by 48 h and a remnant low by 96 h, but this could occur even sooner if the stronger shear values noted in the SHIPS guidance are realized. The GFS simulated satellite imagery suggests the system could be devoid of deep convection as early as day 3 of the forecast period. The storms estimated motion is a somewhat uncertain 295/11 kt. A slight increase in forward speed is expected during the next couple of days as Odalys is steered northwestward by a low- to mid-level ridge centered over southern Texas and northern Mexico. Then, the cyclone should gradually slow down and turn westward as this ridge weakens due to the aforementioned shortwave trough. By 72 h, the storm will be steered southwestward by another low- to mid-level ridge building to its northwest. The track models are in decent agreement, and the official NHC track forecast lies near the center of the guidance envelope closest to the track consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 14.1N 116.1W 35 KT 40 MPH 12H 04/0600Z 15.2N 117.9W 40 KT 45 MPH 24H 04/1800Z 16.8N 120.1W 40 KT 45 MPH 36H 05/0600Z 17.9N 122.0W 35 KT 40 MPH 48H 05/1800Z 18.5N 123.7W 30 KT 35 MPH 60H 06/0600Z 18.5N 125.4W 25 KT 30 MPH 72H 06/1800Z 18.0N 126.5W 25 KT 30 MPH 96H 07/1800Z 16.0N 128.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 08/1800Z...DISSIPATED $$ Forecaster Reinhart/Beven

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Hurricane Eta Forecast Discussion Number 12

2020-11-03 15:48:10| National Hurricane Center (Atlantic)

Issued at 1000 AM EST Tue Nov 03 2020 000 WTNT44 KNHC 031448 TCDAT4 Hurricane Eta Discussion Number 12 NWS National Hurricane Center Miami FL AL292020 1000 AM EST Tue Nov 03 2020 Eta appears to have peaked in intensity overnight as an eyewall replacement cycle occurred early this morning. Radar data from San Andres revealed concentric eyewalls and the last images received from that radar early this morning suggests that the inner-eye wall had weakened. Around that time, the eye became cloud filled and less distinct in infrared satellite imagery. An Air Force Reserve reconnaissance aircraft that provided a couple of center fixes this morning reported that the minimum pressure has risen about 15 mb since last evening. The plane measured a peak flight-level wind of 127 kt, and a few SFMR winds slightly higher, but those winds were flagged as suspect. A dropwindsonde in the southeastern eyewall measured a surface wind of 138 kt, but the mean-layer average winds from the sonde supports a much lower intensity, and the instantaneous surface wind from that instrument is likely more representative of a wind gust. Based on the above data, the initial intensity is set at 125 kt for this advisory. Nonetheless, Eta is an extremely severe hurricane, capable of causing very high storm surges and catastrophic damage. Once the center of the hurricane moves onshore later today, rapid weakening is expected. It is still not certain if the surface circulation will survive its trek over Central America during the next several days, but the official forecast continues to show the remnants of Eta emerging over the northwestern Caribbean Sea late this week. Eta has been meandering just offshore of the coast of Nicaragua this morning, but the longer term motion is 255/4 kt. The hurricane should turn westward very soon with the center crossing the coast today. A ridge to the north of Eta should steer the cyclone on a faster westward to west-northwestward heading over northern Nicaragua and Honduras over the next couple of days. After 72 hours, a developing trough over the northern Gulf of Mexico should cause Eta or its remnants to turn northward and then northeastward. Given that the system is expected to remain over land for at least a couple of days, there continues to be significant uncertainty in the long range portion of the track and intensity forecast. Since Eta is likely to be a very slow-moving system after it makes landfall in Central America, torrential rains and inland flooding will be an extremely serious threat over the next few days. Key Messages: 1. Catastrophic wind damage is expected where Eta's eyewall moves onshore along the northeastern coast of Nicaragua. Tropical-storm- force or greater winds are already occuring within the Hurricane Warning area in Nicaragua. A Tropical Storm Warning is also in effect for the northeastern coast of Honduras. 2. A catastrophic and life-threatening storm surge, along with destructive waves, are expected along portions of the northeastern coast of Nicaragua near and to the north of where the center makes landfall. Water levels could reach as high as 14 to 21 feet above normal tide levels in some parts of the hurricane warning area. 3. Through Friday evening, heavy rainfall from Eta will lead to catastrophic, life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Flash and river flooding is also possible across Jamaica, southeast Mexico, El Salvador, southern Haiti, and the Cayman Islands. FORECAST POSITIONS AND MAX WINDS INIT 03/1500Z 13.6N 83.2W 125 KT 145 MPH 12H 04/0000Z 13.5N 83.8W 100 KT 115 MPH...INLAND 24H 04/1200Z 13.7N 84.9W 45 KT 50 MPH...INLAND 36H 05/0000Z 14.2N 86.5W 30 KT 35 MPH...INLAND 48H 05/1200Z 14.7N 88.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 06/0000Z 15.2N 89.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 06/1200Z 15.7N 89.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 07/1200Z 17.5N 86.5W 25 KT 30 MPH...OVER WATER 120H 08/1200Z 20.0N 82.5W 35 KT 40 MPH $$ Forecaster Brown

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Hurricane Eta Forecast Discussion Number 11

2020-11-03 09:55:04| National Hurricane Center (Atlantic)

Issued at 400 AM EST Tue Nov 03 2020 000 WTNT44 KNHC 030854 TCDAT4 Hurricane Eta Discussion Number 11 NWS National Hurricane Center Miami FL AL292020 400 AM EST Tue Nov 03 2020 Eta remains an extremely well-organized hurricane with a distinct eye embedded within cloud tops colder than -80C. Based on continuity from the earlier Hurricane Hunter observations and Dvorak classifications from TAFB and SAB, the current intensity estimate remains 130 kt. Images from the San Andres radar show at least one concentric eyewall, and this structure has likely stopped the rapid deepening process. Nonetheless, Eta is an extremely severe hurricane, capable of causing very high storm surges and catastrophic damage. After the center moves inland later today, rapid weakening is likely while the circulation interacts with land. The official forecast is similar to the Decay-SHIPS guidance, and shows the cyclone weakening to a depression by tomorrow. It is not certain that the surface circulation will survive after moving over Central America for the next 3 days or so. The official forecast shows the system, perhaps at first the upper-level remnant of Eta, emerging over the northwestern Caribbean Sea in the latter part of the forecast period. It should be noted that both the intensity and track at 4-5 days are highly uncertain at this time. The hurricane has slowed down and is now moving a little south of west or about 250/4 kt. This motion will take the center across the coast in the Hurricane Warning area very soon. A weak ridge to the north of Eta should cause the cyclone to move west to west-northwest, over Central America, during the next few days. By 96-120 hours, a trough developing over the Gulf of Mexico should cause the system to turn northward and northeastward but, as noted earlier, this future track is quite uncertain. Since Eta is likely to be a very slow-moving system after it makes landfall in Central America, torrential rains and inland flooding will be an extremely serious threat over the next few days. Key Messages: 1. Catastrophic wind damage is expected where Eta's eyewall moves onshore along the northeastern coast of Nicaragua this morning. Tropical-storm-force or greater winds are already occuring within the Hurricane Warning area in Nicaragua. A Tropical Storm Warning is also in effect for the northeastern coast of Honduras. 2. A catastrophic and life-threatening storm surge, along with destructive waves, are expected along portions of the northeastern coast of Nicaragua near and to the north of where the center makes landfall. Water levels could reach as high as 14 to 21 feet above normal tide levels in some parts of the hurricane warning area. Preparations to protect life and property should now be complete. 3. Through Friday evening, heavy rainfall from Eta will lead to catastrophic, life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Flash and river flooding is also possible across Jamaica, southeast Mexico, El Salvador, southern Haiti, and the Cayman Islands. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 13.8N 83.1W 130 KT 150 MPH 12H 03/1800Z 13.8N 83.6W 110 KT 125 MPH...INLAND 24H 04/0600Z 13.8N 84.5W 50 KT 60 MPH...INLAND 36H 04/1800Z 14.0N 85.9W 30 KT 35 MPH...INLAND 48H 05/0600Z 14.5N 87.5W 25 KT 30 MPH...INLAND 60H 05/1800Z 15.0N 88.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 06/0600Z 15.7N 89.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 07/0600Z 17.0N 88.0W 25 KT 30 MPH...OVER WATER 120H 08/0600Z 19.0N 83.5W 35 KT 40 MPH $$ Forecaster Pasch

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Hurricane Eta Forecast Discussion Number 10

2020-11-03 03:59:22| National Hurricane Center (Atlantic)

Issued at 1000 PM EST Mon Nov 02 2020 000 WTNT44 KNHC 030259 TCDAT4 Hurricane Eta Discussion Number 10 NWS National Hurricane Center Miami FL AL292020 1000 PM EST Mon Nov 02 2020 An Air Force Reserve reconnaissance aircraft has found that Eta has explosively deepened into a strong category 4 hurricane with maximum sustained winds of 130 kt and a minimum central pressure of 927 mb. Eta has maintained a small 10-nmi-wide eye that is evident in satellite imagery and on the San Andreas, Colombia, weather radar. The radar data also suggest that concentric eyewalls may be forming, which would be an indication of the onset of an eyewall replacement cycle (ERC) and a capping of Eta's intensity and also an end to the rapid intensification cycle of the past 36 hours. The initial intensity of 130 kt kt is based on 700-mb flight-level winds of 137 kt and SFMR surface winds of 130 kt. Some additional strengthening is expected, and Eta could become a category 5 hurricane before landfall occurs. After landfall, Eta should quickly weaken while it moves over the mountainous terrain of Central America. Eta has slowed and is now moving southwestward or 245/06 kt. There is no significant change to previous track forecast reasoning. A mid-level ridge over the south-central United States should steer Eta west-southwestward toward the coast of Nicaragua with the hurricane making landfall early Tuesday. After landfall, Eta should turn westward and then west-northwestward, and move across Central America through Thursday. Eta's low-level circulation may not survive its passage over the mountainous terrain of Central America, but most of the global models continue to depict a cyclone or its remnants moving over the northwestern Caribbean Sea by late-week and into the weekend. Therefore, the new NHC track forecast continues to show the system emerging over the northwestern Caribbean late in the period, although this portion of the track forecast remains uncertain. Since Eta is likely to be a very slow-moving system after it makes landfall in Central America, torrential rains and flooding will be a major threat. Key Messages: 1. Catastrophic wind damage is expected where Eta's eyewall moves onshore along the northeastern coast of Nicaragua tonight or early Tuesday. Tropical storm force winds are beginning to reach the coast within the Hurricane Warning area in Nicaragua, and residents there should have completed their preparations. A Tropical Storm Warning is also in effect for the northeastern coast of Honduras. 2. A catastrophic and life-threatening storm surge, along with destructive waves, are expected along portions of the northeastern coast of Nicaragua near and to the north of where the center makes landfall. Water levels could reach as high as 14 to 21 feet above normal tide levels in some parts of the hurricane warning area. Preparations to protect life and property should now be complete. 3. Through Friday evening, heavy rainfall from Eta will likely lead to catastrophic, life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Flash and river flooding is also possible across Jamaica, southeast Mexico, El Salvador, southern Haiti, and the Cayman Islands. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 14.1N 82.7W 130 KT 150 MPH 12H 03/1200Z 13.9N 83.3W 140 KT 160 MPH 24H 04/0000Z 13.9N 84.0W 90 KT 105 MPH...INLAND 36H 04/1200Z 13.9N 85.0W 45 KT 50 MPH...INLAND 48H 05/0000Z 14.3N 86.3W 30 KT 35 MPH...INLAND 60H 05/1200Z 14.8N 87.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 06/0000Z 15.4N 88.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 07/0000Z 16.8N 87.9W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 08/0000Z 17.9N 85.3W 40 KT 45 MPH $$ Forecaster Stewart

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