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Hurricane Zeta Forecast Discussion Number 18
2020-10-29 03:58:39| National Hurricane Center (Atlantic)
Issued at 1000 PM CDT Wed Oct 28 2020 000 WTNT43 KNHC 290258 TCDAT3 Hurricane Zeta Discussion Number 18 NWS National Hurricane Center Miami FL AL282020 1000 PM CDT Wed Oct 28 2020 The center of Zeta made landfall on the Louisiana coast south of Cocodrie at about 4 pm CDT with maximum sustained winds of about 95 kt. Since then, the hurricane has raced across southeastern Louisiana and is now over southeastern Mississippi. While the sustained winds have been coming down, the satellite presentation is actually not very degraded for a system that has been over land for this long, and there have been reports of 100-mph wind gusts during the past couple of hours. The initial wind speed is set to 70 kt on the basis of radar velocities and the decay-SHIPS model. The hurricane is accelerating tonight toward the northeast or 040/27 kt. While Zeta should continue to weaken due to land effects, strong gusty winds are likely to occur near and east of the center due to the cyclone moving rapidly northeastward, allowing these strong winds to spread well inland. Little change was made to the intensity forecast. Zeta should become extratropical and merge with a front before moving off the Mid-Atlantic coast, eventually merging with a frontal boundary in a couple of days. The official track forecast most closely follows a blend of the model consensus and the GFS, and is faster than the last NHC track. Note that the wind gust factor for this hurricane is higher than typical for a tropical cyclone, and that is reflected in the Forecast/Advisory product. KEY MESSAGES: 1. A dangerous storm surge is continuing along portions of the Mississippi and Alabama coastline and will gradually subside in the early morning hours on Thursday. 2. Dangerous hurricane conditions expected to continue for the next few hours near and along the Mississippi and Alabama coastlines. Tropical storm conditions will also continue for portions of the Tropical Storm Warning area along the Alabama and far western Florida Panhandle coasts. 3. Strong, damaging wind gusts, which could cause tree damage and power outages, will spread well inland across portions of southeastern Mississippi, Alabama, northern Georgia, the Carolinas, and southeastern Virginia overnight and Thursday due to Zeta's fast forward speed. Wind gusts could be especially severe across the southern Appalachian Mountains on Thursday. 4. Through Thursday, heavy rainfall is expected from portions of the central U.S. Gulf Coast into the Mid-Mississippi Valley, Ohio Valley, southern to central Appalachians, and Mid-Atlantic States near and in advance of Zeta. This rainfall will lead to flash, urban, small stream, and minor river flooding. FORECAST POSITIONS AND MAX WINDS INIT 29/0300Z 31.5N 88.7W 70 KT 80 MPH...INLAND 12H 29/1200Z 35.5N 83.5W 45 KT 50 MPH...INLAND 24H 30/0000Z 39.5N 73.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 36H 30/1200Z 42.5N 59.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 31/0000Z...DISSIPATED $$ Forecaster Blake
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Hurricane Zeta Forecast Discussion Number 17
2020-10-28 22:00:35| National Hurricane Center (Atlantic)
Issued at 400 PM CDT Wed Oct 28 2020 000 WTNT43 KNHC 282100 TCDAT3 Hurricane Zeta Discussion Number 17 NWS National Hurricane Center Miami FL AL282020 400 PM CDT Wed Oct 28 2020 The center of Zeta is in the Terrebone Bay area of Louisiana and is making landfall near Cocodrie. Somewhat surprisingly, Zeta has rapidly intensified this afternoon. Although the hurricane has been moving over marginally warm SSTs and relatively low heat content waters, it has intensified from 80 kt to 95 kt in about 6 hours. It is possible that this intensification can be at least partly attributable to a conducive interaction with with an upper-level trough located a few hundred miles to the west-northwest of Zeta. The 95-kt intensity estimate for Zeta is based on a blend of flight-level, SFMR and dropsonde winds from an Air Force Reserve Hurricane Hunter aircraft. Since the center will either be interacting with land or moving over land from this point, a weakening trend should begin tonight. The official intensity forecast is close to the Decay-SHIPS guidance, which should handle the exponential decay of wind seed for tropical cyclones moving over land. In 24 hours or so, the global models depict the system as being embedded in a front while it approaches the United States east coast. Thus the official forecast shows an extratropical cyclone at that point and beyond. After 48 hours, the models show the low becoming elongated and absorbed into the frontal zone. Zeta has turned toward the north-northeast and the forward speed is increasing, with the motion now 025/21 kt. The cyclone should accelerate north-northeastward ahead of a 500-mb trough through tonight. The system should then move even faster toward the northeast, ahead of the trough, and across the southeastern and eastern United States on Thursday. Post-tropical Zeta should move east-northeastward, in the mid-level westerlies, into the Atlantic Friday morning. The official track forecast follows the correct model consensus, HCCA, rather closely. Given Zeta's acceleration after landfall, strong winds are likely to spread well inland over the southeastern U.S. overnight and early Thursday. KEY MESSAGES: 1. A life-threatening storm surge is beginning along portions of the northern Gulf Coast, with the highest inundation expected to occur somewhere between Port Fourchon, Louisiana, and Dauphin Island, Alabama, especially along the Mississippi coast. Overtopping of local, non-federal levee systems is possible within southeastern Louisiana outside of the Hurricane and Storm Damage Risk Reduction System. 2. Extremely dangerous hurricane conditions are spreading across portions of the Hurricane Warning area along the southeastern Louisiana coast and will spread to the Mississippi coast this evening. Tropical storm conditions will spread into portions of the Tropical Storm Warning area along the Alabama and far western Florida Panhandle coasts in the next few hours. 3. Strong, damaging wind gusts, which could cause tree damage and power outages, will spread well inland across portions of southeastern Mississippi, Alabama, northern Georgia, the Carolinas, and southeastern Virginia tonight and Thursday due to Zeta's fast forward speed. Wind gusts could be especially severe across the southern Appalachian Mountains on Thursday. 4. Through Thursday, heavy rainfall is expected from portions of the central U.S. Gulf Coast into the Mid-Mississippi Valley, Ohio Valley, southern to central Appalachians, and Mid-Atlantic States near and in advance of Zeta. This rainfall will lead to flash, urban, small stream, and minor river flooding. FORECAST POSITIONS AND MAX WINDS INIT 28/2100Z 29.2N 90.6W 95 KT 110 MPH...ON THE COAST 12H 29/0600Z 32.8N 87.0W 55 KT 65 MPH...INLAND 24H 29/1800Z 37.5N 78.8W 40 KT 45 MPH...POST-TROP/INLAND 36H 30/0600Z 41.0N 68.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 30/1800Z 44.0N 57.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 60H 31/0600Z...DISSIPATED $$ Forecaster Pasch
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Hurricane Zeta Forecast Discussion Number 16
2020-10-28 15:50:01| National Hurricane Center (Atlantic)
Issued at 1000 AM CDT Wed Oct 28 2020 000 WTNT43 KNHC 281449 TCDAT3 Hurricane Zeta Discussion Number 16 NWS National Hurricane Center Miami FL AL282020 1000 AM CDT Wed Oct 28 2020 Zeta has a well-organized cloud pattern on satellite images, and the eye has been fairly well-defined. Strong upper-level outflow is evident over the northern semicircle of the hurricane. Reports from Air Force and NOAA Hurricane Hunter aircraft indicate that the system had continued to strengthen over the past few hours. Peak 700-mb flight level winds were 89 kt, which equates to a maximum surface wind of about 80 kt, and The central pressure has fallen to 976 mb. Zeta still has a few hours to intensify before it begins to move over the cooler waters of the northern Gulf of Mexico, and southwesterly shear is likely to increase by the time the center reaches the coast. Even if a little weakening begins later today, however, Zeta should maintain hurricane strength through landfall. The official intensity forecast is near the high end of the model guidance. In 36 hours or so, the global models clearly depict the system as a frontal wave approaching the United States east coast so the official forecast shows an extratropical cyclone at that point and beyond. After 48 hours, the models show the low becoming elongated and absorbed into the frontal zone. The hurricane has turned northward and is now moving at around 010/16 kt. A strong 500-mb trough moving into Texas will continue to move eastward during the next 36-48 hours. The flow ahead of this trough will cause Zeta to accelerate north-northeastward and move inland along the central Gulf Coast in 6-12 hours. On Thursday, the cyclone will then move northeastward on the east side of the trough, at an even faster pace, over the southeastern United States. By early Friday, the system should move east- northeastward in the westerlies and into the western Atlantic as an extratropical cyclone. The official track forecast is close to the previous one and generally follows the dynamical model consensus. Given Zeta's acceleration near and after landfall, strong winds are likely to spread well inland over the southeastern U.S. this evening and early Thursday. KEY MESSAGES: 1. A life-threatening storm surge is expected along portions of the northern Gulf Coast beginning later today, with the highest inundation occurring between Port Fourchon, Louisiana, and Dauphin Island, Alabama. Residents in the Storm Surge Warning area should follow any advice given by local officials. Overtopping of local, non-federal levee systems is possible within southeastern Louisiana outside of the Hurricane and Storm Damage Risk Reduction System. 2. Hurricane conditions are expected this afternoon and evening within portions of the Hurricane Warning area along the southeastern Louisiana and Mississippi coasts. Tropical storm conditions are expected within portions of the Tropical Storm Warning area along the Alabama and far western Florida Panhandle coasts. 3. Strong, damaging wind gusts, which could cause tree damage and power outages, will spread well inland across portions of southeastern Mississippi, Alabama, northern Georgia, the Carolinas, and southeastern Virginia tonight and Thursday due to Zeta's fast forward speed. Wind gusts could be especially severe across the southern Appalachian Mountains on Thursday. 4. Through Thursday, heavy rainfall is expected from portions of the central U.S. Gulf Coast into the Mid-Mississippi Valley, Ohio Valley, southern to central Appalachians, and Mid-Atlantic States near and in advance of Zeta. This rainfall will lead to flash, urban, small stream, and minor river flooding. FORECAST POSITIONS AND MAX WINDS INIT 28/1500Z 26.9N 91.7W 80 KT 90 MPH 12H 29/0000Z 30.1N 89.9W 80 KT 90 MPH...INLAND 24H 29/1200Z 35.3N 83.9W 40 KT 45 MPH...INLAND 36H 30/0000Z 39.1N 74.2W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 30/1200Z 41.5N 63.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 31/0000Z...DISSIPATED $$ Forecaster Pasch
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Hurricane Zeta Forecast Discussion Number 15
2020-10-28 10:00:55| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Wed Oct 28 2020 000 WTNT43 KNHC 280900 TCDAT3 Hurricane Zeta Discussion Number 15 NWS National Hurricane Center Miami FL AL282020 400 AM CDT Wed Oct 28 2020 The satellite presentation of Zeta has improved significantly overnight with deep convection wrapping around an eye that at times as been fairly well defined. An Air Force Reserve Hurricane Hunter aircraft that has just began its reconnaissance mission into Zeta has reported a pressure that has fallen to 982 mb and a 25-30 n-mi-wide eye during it first pass through the center. It is somewhat surprising that the plane did not report stronger winds during its northeast eyewall pass given the improved satellite presentation, and using a blend of the aircraft data and recent objective and subjective satellite estimates yields and initial intensity of 75 kt. It is possible the winds have yet to catch up to the improved satellite appearance, but since Zeta will moving over warm waters and in a light wind shear environment this morning some additional strengthening is likely. Although cooler waters and increasing southwesterly upper-level winds over the northern Gulf of Mexico are likely to cause the cyclone's intensity to level-off or even come down slightly, Zeta is expected to reach the northern Gulf coast as significant hurricane by late this afternoon. The NHC intensity forecast is at the upper-end of the guidance, a little above the latest HWRF prediction. After landfall, Zeta will weaken while it moves over the southeastern United States, but the cyclone is forecast to become an extratropical gale-force low pressure area off the Mid-Atlantic coast Thursday night. The post-tropical cyclone should be absorbed by frontal boundary over the western Atlantic on Friday. Zeta has turned north-northwestward and has begun to accelerate as anticipated. A vigorous upper-level low moving into west Texas will cause Zeta to accelerate north-northeastward today, which will bring the center of the hurricane over southeastern Louisiana by late this afternoon. The cyclone is expected to continue to accelerate ahead of the trough over the southeastern United States tonight and Thursday. The dynamical model are in very good agreement and the latest NHC track is a blend of the various global models. The new track forecast is very close the previous official forecast. Given Zeta's acceleration near landfall, strong winds are likely to spread well inland along the northern Gulf coast this evening and tonight. KEY MESSAGES: 1. A life-threatening storm surge is expected along portions of the northern Gulf Coast by late today, with the highest inundation occurring somewhere between the Mouth of the Pearl River and Dauphin Island, Alabama. Residents in the Storm Surge Warning area should follow any advice given by local officials. 2. Hurricane conditions are expected this afternoon within portions of the Hurricane Warning area between Morgan City, Louisiana, and the Mississippi/Alabama border. Damaging winds, especially in gusts, will spread well inland across portions of southeast Mississippi and southern and central Alabama tonight due to Zeta's fast forward speed. 3. Through Thursday, heavy rainfall is expected from portions of the central U.S. Gulf Coast into the Tennessee Valley, Ohio Valley, Southern to Central Appalachians, and Mid-Atlantic States near and in advance of Zeta. This rainfall will lead to flash, urban, small stream, and minor river flooding. FORECAST POSITIONS AND MAX WINDS INIT 28/0900Z 25.1N 91.8W 75 KT 85 MPH 12H 28/1800Z 27.9N 91.1W 85 KT 100 MPH 24H 29/0600Z 32.8N 87.5W 50 KT 60 MPH...INLAND 36H 29/1800Z 37.5N 79.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 48H 30/0600Z 40.5N 67.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 30/1800Z...DISSIPATED $$ Forecaster Brown
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Tropical Storm Zeta Forecast Discussion Number 14
2020-10-28 03:55:26| National Hurricane Center (Atlantic)
Issued at 1000 PM CDT Tue Oct 27 2020 000 WTNT43 KNHC 280255 TCDAT3 Tropical Storm Zeta Discussion Number 14 NWS National Hurricane Center Miami FL AL282020 1000 PM CDT Tue Oct 27 2020 Satellite images show that Zeta is becoming better organized tonight with a ragged eye feature now present, plenty of deep convection and a more symmetric appearance. The Air Force Reserve Hurricane Hunter aircraft has found increasing winds on this flight, recently recording peak flight-level winds of 65 kt and a minimum pressure of around 990 mb. The initial wind speed is raised to 60 kt on the basis of the wind data. The improving cloud pattern of Zeta is usually one that favors intensification in the short term. In addition, microwave data from a couple hours ago indicated that a 37 GHz low-level ring was present, which also can be a harbinger of strengthening, and sometimes that strengthening is on the rapid side. Since the storm remains over warm water with fairly light shear, the NHC forecast still anticipates Zeta regaining hurricane intensity within the next 6 hours and making a second landfall as a hurricane. The new NHC forecast is a little higher than the previous one, remaining on the high side of the guidance. After landfall, Zeta is likely to become an extratropical cyclone while it approaches the eastern United States in a couple of days, and become absorbed by the same frontal system. Zeta is moving northwestward a little faster tonight (325/13 kt). The storm is expected to turn northward and move along the western side of a mid-level anticyclone centered east of Florida through Wednesday morning. A deep cold low (responsible for the southern Plains ice storm) approaching from the west will cause Zeta to sharply accelerate north-northeastward and move inland along the southeastern Louisiana coast Wednesday afternoon. The cyclone should continue to accelerate ahead of the trough and move over the southeastern and eastern U.S. through Thursday. Similar to the last forecast, the official track forecast was moved slightly westward during the first 24 hours, not too dissimilar from a consensus of the latest GFS, UKMET and ECMWF forecasts. Given Zeta's acceleration near landfall, strong winds are likely to spread well inland along the northern Gulf coast Wednesday night. KEY MESSAGES: 1. A life-threatening storm surge is expected along portions of the northern Gulf Coast by late Wednesday, with the highest inundation occurring somewhere between the Mouth of the Pearl River and Dauphin Island, Alabama. Residents in the Storm Surge Warning area should follow any advice given by local officials. 2. Hurricane conditions are expected Wednesday afternoon within portions of the Hurricane Warning area between Morgan City, Louisiana, and the Mississippi/Alabama border. Damaging winds, especially in gusts, will spread well inland across portions of southeast Mississippi and southern Alabama Wednesday night due to Zeta's fast forward speed. 3. Localized heavy rainfall from Zeta will continue tonight in portions of the Yucatan Peninsula of Mexico and western Cuba where additional flash flooding is possible in urban areas. Between tonight and Thursday, heavy rainfall is expected from portions of the central U.S. Gulf Coast into the Ohio Valley and Mid-Atlantic States near and in advance of Zeta. This rainfall will lead to flash, urban, small stream, and minor river flooding. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 23.8N 91.2W 60 KT 70 MPH 12H 28/1200Z 26.0N 91.7W 75 KT 85 MPH 24H 29/0000Z 30.2N 89.7W 65 KT 75 MPH...INLAND 36H 29/1200Z 35.0N 84.5W 30 KT 35 MPH...INLAND 48H 30/0000Z 39.5N 74.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 30/1200Z...DISSIPATED $$ Forecaster Blake
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