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Tropical Storm Elsa Forecast Discussion Number 30

2021-07-07 17:04:28| National Hurricane Center (Atlantic)

Issued at 1100 AM EDT Wed Jul 07 2021 000 WTNT45 KNHC 071503 CCA TCDAT5 Tropical Storm Elsa Discussion Number 30...Corrected NWS National Hurricane Center Miami FL AL052021 1100 AM EDT Wed Jul 07 2021 Corrected Taylor County to Dixie County in the first paragraph. An Air Force Hurricane Hunter aircraft has made several fixes in Elsa this morning, and recent observations from the plane indicated that the center is now on the coast making landfall. The aircraft found that the central pressure remained about steady with maximum winds of 55 kts up to landfall. Sustained tropical-storm-force winds are being reported from observing sites within the warning area, with an unofficial report of a sustained wind of 54 kt gusting to 62 kt at Horseshoe Beach in Dixie County, Florida during the past half hour. Center fixes indicate that Elsa has continued northward, with a motion estimate of 360/12 kt. Elsa should turn toward the north-northeast today as it moves along the northwestern periphery of an Atlantic subtropical ridge. On Thursday, the cyclone should begin to accelerate northeastward on the southeast side of a broad mid-tropospheric trough over the eastern United States and Canada. The official track forecast is on top of the latest multi-model consensus, TVCA, solution. This is only slightly to left of the previous NHC track, and shows the center moving near the northeastern U.S. coast within the next 48 hours. Weakening will occur while the cyclone moves over land during the next 36 hours or so, and the official intensity forecast closely resembles the decay-SHIPS guidance. Since winds of 35 kt are possible near the coast well to the southeast of the center within the next day or two, a tropical storm warning is in effect for a portion of the southeast U.S. coast. Some slight reintensification is shown when the center moves near the coast in 48-60 hours. However, since the water temperatures are rather cool near the northeast coast, strengthening will probably be influenced by baroclinic forcing associated with a 500 mb shortwave trough. The system will likely become extratropical by 72 hours if not sooner while it moves through Atlantic Canada. Key Messages: 1. As Elsa moves across the western and northern Florida Peninsula today, heavy rainfall may result in considerable flash, urban, and isolated moderate river flooding. Heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across southeast Georgia and the Lowcountry of South Carolina. Heavy rainfall across the Northeast and New England Thursday and Friday could lead to isolated flash and urban flooding. 2. There is still a danger of life-threatening storm surge along portions of the west coast of Florida today, and a Storm Surge Warning is in effect for that area. 3. Tropical storm conditions wile continue today across portions of the northeast Gulf coast today within the warning area. 4. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next day or two, tropical storm conditions are expected along much of the coasts of Georgia and South Carolina. Tropical storm conditions are also possible along the coast of the mid-Atlantic states by Thursday night or Friday. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 29.9N 83.6W 55 KT 65 MPH 12H 08/0000Z 31.7N 82.9W 35 KT 40 MPH...INLAND 24H 08/1200Z 34.3N 80.9W 30 KT 35 MPH...INLAND 36H 09/0000Z 37.3N 77.6W 30 KT 35 MPH...INLAND 48H 09/1200Z 40.6N 73.3W 35 KT 40 MPH...NEAR COAST 60H 10/0000Z 44.5N 68.0W 40 KT 45 MPH...NEAR COAST 72H 10/1200Z 49.0N 60.9W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 11/1200Z 58.0N 47.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 12/1200Z...DISSIPATED $$ Forecaster Pasch

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Tropical Storm Elsa Forecast Discussion Number 29

2021-07-07 11:06:49| National Hurricane Center (Atlantic)

Issued at 500 AM EDT Wed Jul 07 2021 000 WTNT45 KNHC 070906 TCDAT5 Tropical Storm Elsa Discussion Number 29 NWS National Hurricane Center Miami FL AL052021 500 AM EDT Wed Jul 07 2021 The central convection associated with Elsa dissipated for a time earlier this morning, although the latest radar and satellite imagery shows a new band forming in the northern semicircle. This decrease was likely caused by a combination of shear and dry air entrainment, and it has caused the cyclone to weaken. Aircraft and surface observations indicate the central pressure has risen to near 1004 mb, and the initial intensity is decreased to a possibly generous 55 kt based on aircraft and Doppler radar data. After a slight jog to the left, the storm has resumed a motion of 360/12. This motion should continue for the next 12 h or so until landfall occurs across the northwestern Florida peninsula. Thereafter, a gradual turn toward the north-northeast is expected by, followed by acceleration toward the northeast as Elsa moves into the mid-latitude westerlies. The forecast guidance has shifted a little to the left since the last advisory, and the new forecast track is also nudged in that direction. The new track lies a little to the right of the various consensus models. While little change in strength is forecast before landfall, there is a chance that the new convection could cause a short-lived re-intensification. So, based on this possibility a hurricane warning remains in effect for portions of the west coast of Florida. After landfall, Elsa should weaken as it crosses the southeastern United States, followed by some re-intensification as it accelerates back over the Atlantic. The system is expected to become extratropical by the time it reaches the Canadian Maritimes in 72 h. The new intensity forecast is at the upper edge of the guidance envelope and has only minor adjustments from the previous forecast. Key Messages: 1. As Elsa moves across the western and northern Florida Peninsula today, heavy rainfall may result in considerable flash, urban, and isolated moderate river flooding. Heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across coastal Georgia and the Lowcountry of South Carolina. Heavy rainfall across the Northeast and New England Thursday and Friday could lead to isolated flash and urban flooding. 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida today, and a Storm Surge Warning is in effect for that area. 3. Hurricane conditions are possible during the next several hours along a portion of the west coast of Florida, where a Hurricane Warning is in effect. Tropical storm conditions are occurring across portions of the western Florida peninsula and will continue to spread northward along the west coast of the state within the warning area through today. 4. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next day or two, tropical storm conditions are expected along much of the coasts of Georgia and South Carolina. Tropical storm conditions are also possible along the coast of the mid-Atlantic state by Thursday night or Friday. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 28.5N 83.5W 55 KT 65 MPH 12H 07/1800Z 30.2N 83.3W 50 KT 60 MPH 24H 08/0600Z 32.6N 82.0W 40 KT 45 MPH...INLAND 36H 08/1800Z 35.3N 79.4W 35 KT 40 MPH...INLAND 48H 09/0600Z 38.1N 75.6W 40 KT 45 MPH...INLAND 60H 09/1800Z 41.5N 70.9W 45 KT 50 MPH...OVER WATER 72H 10/0600Z 45.6N 64.6W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 11/0600Z 54.0N 50.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 12/0600Z...DISSIPATED $$ Forecaster Beven

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Hurricane Elsa Forecast Discussion Number 28

2021-07-07 04:57:44| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT Tue Jul 06 2021 000 WTNT45 KNHC 070257 TCDAT5 Hurricane Elsa Discussion Number 28 NWS National Hurricane Center Miami FL AL052021 1100 PM EDT Tue Jul 06 2021 After an earlier flurry of convective bursting and even the development of a eye in radar imagery, Elsa appears to have leveled off over the past couple of hours. Between 2100 UTC and 0000 UTC, WSR-88D radars from Tampa and Key West indicated areas of average Doppler velocities of 75-85 kt between 8000-13,000 ft, which were co-located with convective bands consisting of 50 dBZ and higher reflectivity values, which equates to at least 65 kt surface winds. Elsa's center also passed just barely to the east of Buoy 41023 around 2100 UTC, producing a sustained wind of 49 kt at 3-meters elevation, which equals a 10-meter wind speed of 55 kt on the west side of the cyclone. The strongest 850-mb flight-level wind measured by an Air Force reconnaissance aircraft so far has been 74 kt. However, radar data indicate that the aircraft just missed the strongest winds in the convection by only about 5 n mi. The initial intensity is being held at 65 kt just in case convection redevelops around the ragged eye feature later tonight. Elsa is moving northward, or 360/12 kt. This motion should continue tonight and early Wednesday until landfall occurs across the northwestern Florida peninsula. Thereafter, a gradual turn toward the north-northeast is expected by late Wednesday, followed by some acceleration toward the northeast on Thursday as Elsa rounds the western periphery of a deep-layer subtropical ridge and gets caught up by the southwesterly flow ahead of a mid-level trough. The official track forecast lies between the simple and corrected-consensus tracks models and the previous NHC track forecast. Elsa's inner-core convection looks pretty ragged right now, but the vertical structure has improved based on the reconnaissance data, which indicate that the low-, middle- and upper-level circulations are nearly vertically stacked now. Elsa's ragged eye feature along with the very warm water beneath the cyclone and the upcoming nocturnal convective maximum period could combine to allow convection to redevelop. However, proximity to dry mid-level air just to the west should prevent any significant strengthening from occurring. After landfall, rapid weakening is expected due to increased frictional effects and Elsa's small size. The pressure gradient, however, is forecast by the GFS and ECMWF models to increase between Elsa and a sprawling surface high pressure system over the western Atlantic, which should act to increase the winds to tropical storm force near the coastal areas from Georgia to North Carolina on Wednesday and Thursday. The new NHC intensity forecast is similar to the previous advisory and follows the consensus intensity models HCCA and IVCN. Key Messages: 1. Heavy rain will impact Cuba tonight resulting in significant flooding and mudslides. As Elsa moves across the western and northern Florida Peninsula through Wednesday, heavy rainfall may result in considerable flash, urban, and minor to isolated moderate river flooding. Mid to late week, heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across coastal Georgia and the Lowcountry of South Carolina. 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida tonight and Wednesday, and a Storm Surge Warning is in effect for that area. 3. Hurricane conditions are expected tonight and early Wednesday along a portion of the west coast of Florida, where a Hurricane Warning is in effect. Tropical storm conditions are occurring across portions southwest Florida and will continue to spread northward along the west coast of the state within the warning area through Wednesday morning. 4. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next couple of days, tropical storm conditions are expected along much of the coasts of Georgia and South Carolina. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 27.3N 83.2W 65 KT 75 MPH 12H 07/1200Z 29.0N 83.1W 60 KT 70 MPH 24H 08/0000Z 31.4N 82.5W 45 KT 50 MPH...INLAND 36H 08/1200Z 33.9N 80.5W 35 KT 40 MPH...INLAND 48H 09/0000Z 36.4N 77.4W 35 KT 40 MPH...INLAND 60H 09/1200Z 39.3N 73.3W 40 KT 45 MPH...OVER WATER 72H 10/0000Z 42.8N 68.0W 45 KT 50 MPH...OVER WATER 96H 11/0000Z 51.0N 54.4W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 12/0000Z...DISSIPATED $$ Forecaster Stewart

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Tropical Storm Elsa Forecast Discussion Number 27

2021-07-06 22:39:52| National Hurricane Center (Atlantic)

Issued at 500 PM EDT Tue Jul 06 2021 000 WTNT45 KNHC 062039 TCDAT5 Tropical Storm Elsa Discussion Number 27 NWS National Hurricane Center Miami FL AL052021 500 PM EDT Tue Jul 06 2021 The Hurricane Hunters completed their mission into Elsa a little while ago, and observations from the aircraft indicate that the storm's maximum winds are near 60 kt. Elsa is a sheared tropical cyclone, with the low level center situated on the southwest edge of the main area of deep convection. Much of the western half of the circulation continues to lack significant shower or thunderstorm activity. Moderate westerly vertical shear, along with relatively dry mid-level air, should continue to affect the cyclone until landfall within the next day or so. However this environment should not be hostile enough to prevent some slight strengthening, and Elsa is predicted to become a hurricane overnight. Elsa is moving northward, or 350/9 kt. A continued northward track is likely for the next 24 hours or so as the tropical cyclone moves between the western periphery of an Atlantic subtropical ridge and a broad low pressure area over the northwestern Gulf of Mexico. A turn toward the north-northeast along the northwestern side of the ridge is expected by late tomorrow, followed by an acceleration toward the northeast over the next couple of days ahead of a trough over the eastern United States and eastern Canada. The official track forecast is similar to the previous ones and near or slightly to the right of the model consensus tracks. Key Messages: 1. Heavy rain will impact Cuba tonight resulting in significant flooding and mudslides. As Elsa moves across the western and northern Florida Peninsula through Wednesday, heavy rainfall may result in considerable flash, urban, and minor to isolated moderate river flooding. Mid- to late-week, heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across coastal Georgia and the Lowcountry of South Carolina. 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida tonight and Wednesday, and a Storm Surge Warning is in effect for that area. 3. Hurricane conditions are expected tonight and early Wednesday along a portion of the west coast of Florida, where a Hurricane Warning is in effect. Tropical storm conditions are occurring across portions of the Florida Keys and will spread northward along the west coast of the state within the warning area through Wednesday morning. 4. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next couple of days, tropical storm conditions are expected in a portion of southeastern Georgia and are possible elsewhere along much of the coasts of Georgia and South Carolina. FORECAST POSITIONS AND MAX WINDS INIT 06/2100Z 25.8N 83.0W 60 KT 70 MPH 12H 07/0600Z 27.5N 83.1W 65 KT 75 MPH 24H 07/1800Z 30.0N 82.8W 55 KT 65 MPH...INLAND 36H 08/0600Z 32.3N 81.5W 35 KT 40 MPH...INLAND 48H 08/1800Z 34.8N 78.9W 30 KT 35 MPH...INLAND 60H 09/0600Z 37.4N 75.4W 35 KT 40 MPH...OVER WATER 72H 09/1800Z 40.5N 71.0W 40 KT 45 MPH...OVER WATER 96H 10/1800Z 48.5N 58.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 120H 11/1800Z...DISSIPATED $$ Forecaster Pasch

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Tropical Storm Elsa Forecast Discussion Number 26

2021-07-06 20:05:04| National Hurricane Center (Atlantic)

Issued at 200 PM EDT Tue Jul 06 2021 000 WTNT45 KNHC 061804 TCDAT5 Tropical Storm Elsa Special Discussion Number 26 NWS National Hurricane Center Miami FL AL052021 200 PM EDT Tue Jul 06 2021 This is a special advisory to issue a Hurricane Warning for a portion of the Florida Gulf coast. Recent observations from an Air Force Reserve Unit Hurricane Hunter aircraft indicate that the maximum winds in Elsa are now near 60 kt. However, the aircraft has not yet had a chance to sample the northeastern quadrant, so it is possible that higher winds exist. Although the environment is not conducive for significant strengthening before landfall, only a slight increase in intensity would result in Elsa becoming a hurricane tonight or early Wednesday. Aside from the small adjustments to the 12- and 24-intensity forecasts to reflect the revised current intensity estimate, no other changes have been made to the official forecast. The NHC track forecast reasoning is unchanged from the 1500 UTC advisory. Key Messages: 1. Heavy rain will impact Cuba today resulting in significant flooding and mudslides. As Elsa moves near or along the western Florida Peninsula through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding, with considerable flash and urban flooding possible in southwest and western portions of Florida. Mid to late week, heavy rainfall across coastal Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across coastal Georgia and the Lowcountry of South Carolina. 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida tonight and Wednesday, and a Storm Surge Warning is in effect for that area. 3. Hurricane conditions are expected tonight and early Wednesday along a portion of the west coast of Florida, where a Hurricane Warning is in effect. Tropical storm conditions are occurring across portions of the Florida Keys and are expected to spread northward along much of the west coast of the state through Wednesday morning, where a Tropical Storm Warning is in effect. 4. A Tropical Storm Watch is in effect for the Georgia coast and portions of the South Carolina coast, where tropical storm conditions are possible late Wednesday and early Thursday. FORECAST POSITIONS AND MAX WINDS INIT 06/1800Z 25.4N 83.0W 60 KT 70 MPH 12H 07/0000Z 26.5N 83.0W 65 KT 75 MPH 24H 07/1200Z 28.9N 83.0W 65 KT 75 MPH 36H 08/0000Z 31.3N 82.0W 35 KT 40 MPH...INLAND 48H 08/1200Z 33.8N 80.0W 30 KT 35 MPH...INLAND 60H 09/0000Z 36.7N 76.4W 35 KT 40 MPH...INLAND 72H 09/1200Z 39.5N 72.5W 40 KT 45 MPH...OVER WATER 96H 10/1200Z 48.0N 60.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 120H 11/1200Z...POST-TROP/EXTRATROP $$ Forecaster Pasch

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