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Tropical Storm Jose Forecast Discussion Number 65

2017-09-21 16:37:34| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Thu Sep 21 2017 000 WTNT42 KNHC 211437 TCDAT2 Tropical Storm Jose Discussion Number 65 NWS National Hurricane Center Miami FL AL122017 1100 AM AST Thu Sep 21 2017 Satellite and radar data suggest that Jose is gradually spinning down. The convective bands are relatively shallow, except over the western quadrants where the cloud tops are a bit colder. The outer-most bands are very near the offshore islands of southeastern New England, where there have been reports of tropical-storm-force winds, especially in gusts. The Air Force Hurricane Hunters investigated Jose earlier this morning, and a combination of the flight-level winds, SFMR observations, and dropsonde data support holding the initial intensity at 50 kt. The intensity forecast appears straightforward. Cool waters, dry air, and an expected increase in wind shear should cause Jose to steadily weaken and lead to post-tropical transition within the next 24 hours. The post-tropical system is predicted to degenerate into a trough by day 4, as suggested by the GFS and ECMWF models. The NHC intensity forecast is just an update of the previous one, and it lies close to the consensus models. As previously predicted, Jose has become stationary. Since the storm is expected to remain in weak steering currents for the next few days, Jose is forecast to meander off the coast of southeastern New England until it dissipates. This track prediction is not too different from the previous one, and it lies near the middle of the guidance. KEY MESSAGES: 1. Tropical-storm-force winds, especially in gusts, are occuring within the tropical storm warning area. These conditions are expected to continue through tonight. 2. Minor coastal flooding is possible along portions of the coast of southern New England during the next few days. Please see products issued by local National Weather Service forecast offices. 3. Swells generated by Jose are affecting Bermuda and much of the U.S. east coast, and will likely cause dangerous surf and rip current conditions for the next few days in these areas. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 39.6N 68.2W 50 KT 60 MPH 12H 22/0000Z 39.5N 68.3W 45 KT 50 MPH 24H 22/1200Z 39.6N 68.9W 40 KT 45 MPH...POST-TROPICAL 36H 23/0000Z 39.5N 69.2W 40 KT 45 MPH...POST-TROPICAL 48H 23/1200Z 39.4N 69.3W 35 KT 40 MPH...POST-TROPICAL 72H 24/1200Z 39.1N 68.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 25/1200Z...DISSIPATED $$ Forecaster Cangialosi

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Hurricane Maria Forecast Discussion Number 21

2017-09-21 10:43:29| National Hurricane Center (Atlantic)

Issued at 500 AM AST Thu Sep 21 2017 000 WTNT45 KNHC 210843 TCDAT5 Hurricane Maria Discussion Number 21 NWS National Hurricane Center Miami FL AL152017 500 AM AST Thu Sep 21 2017 Although the large, 40 n mi diameter, eye of the hurricane is still a little ragged-looking, it is gradually becoming better defined, and a ring of cold cloud tops is intensifying around the eye. The current intensity estimate is 100 kt based on earlier Air Force Hurricane Hunter data and recent Dvorak classifications from TAFB and SAB. Maria is likely to move over warm waters with moderate southwesterly vertical shear for the next couple of days. Maria's well-developed upper-level outflow suggests that shear is probably not having much influence over the hurricane at this time. Although the numerical guidance is not very aggressive about intensification, based on the current trends of the cloud pattern, some strengthening seems likely over the next day or so. Later in the forecast period, shear will probably cause gradual weakening. The official intensity forecast is a little above the latest model consensus. Maria continues its northwestward motion, at about 315/8 kt. The hurricane is expected to turn north-northwestward and northward around a subtropical ridge over the Atlantic for the next 2 to 3 days. Late in the forecast period, a mid-level high over the northeastern U.S. could slow the forward motion somewhat. This high is forecast by the global models to subsequently weaken however, which should allow Maria to turn north-northeastward in the flow on the northwestern edge of a subtropical ridge over the west-central Atlantic. The official track forecast lies between the corrected consensus guidance and the latest ECMWF prediction. This is quite similar to the previous NHC track. KEY MESSAGES: 1. Heavy rainfall is expected to continue, and catastrophic flash flooding is occurring in Puerto Rico, especially in areas of mountainous terrain. Everyone in Puerto Rico should continue to follow advice from local officials to avoid these life-threatening flooding conditions. 2. A Hurricane Warning is in effect for the northern coast of the Dominican Republic, the Turks and Caicos Islands, and the southeastern Bahamas, where Maria is expected to bring dangerous wind, storm surge, and heavy rainfall. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 19.6N 68.4W 100 KT 115 MPH 12H 21/1800Z 20.5N 69.3W 105 KT 120 MPH 24H 22/0600Z 21.6N 70.4W 110 KT 125 MPH 36H 22/1800Z 22.9N 71.1W 105 KT 120 MPH 48H 23/0600Z 24.3N 71.7W 100 KT 115 MPH 72H 24/0600Z 27.4N 72.3W 100 KT 115 MPH 96H 25/0600Z 30.0N 72.0W 90 KT 105 MPH 120H 26/0600Z 32.5N 70.5W 80 KT 90 MPH $$ Forecaster Pasch

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Tropical Storm Jose Forecast Discussion Number 64

2017-09-21 10:38:31| National Hurricane Center (Atlantic)

Issued at 500 AM AST Thu Sep 21 2017 000 WTNT42 KNHC 210838 TCDAT2 Tropical Storm Jose Discussion Number 64 NWS National Hurricane Center Miami FL AL122017 500 AM AST Thu Sep 21 2017 Jose's structure continues to consist of bands of shallow to moderate convection that are well removed to from the center, mainly in the northeast and northwest quadrants. Dvorak Final-T numbers from TAFB and SAB have fallen a little bit, but due to the lack of deep convection near the center, it isn't clear how applicable the Dvorak technique is in this case. The intensity has therefore been held at 50 kt, in deference to earlier ASCAT and aircraft data. Another reconnaissance mission is scheduled for later this morning, and this should provide more information on Jose's intensity and wind radii. The intensity guidance is still in very good agreement that Jose will continue to gradually weaken. I have no reason to doubt this, since Jose will remain over cold waters and embedded within a fairly dry environment. Little change was made to the previous intensity forecast, except to show Jose becoming post-tropical within 36 hours, based on the latest GFS and ECMWF model runs. A deep-layer trough to the northeast of Jose has continued to pull away, and the tropical storm has come to a near stop. The estimated motion is 90/2 kt, but it may be even slower than that. The global models continue to agree that Jose will remain within weak steering flow through the forecast period. The new NHC forecast remains close to the various consensus aids and keeps Jose nearly stationary through 96 h. KEY MESSAGES: 1. While the center of Jose is forecast to remain offshore of the U.S. east coast, the large cyclone is expected to cause some direct impacts in portions of extreme southeastern New England during the next day or two, and a tropical storm warning remains in effect for Cape Cod, Block Island, Martha's Vineyard, and Nantucket. 2. Minor coastal flooding is possible along portions of the coast of southern New England during the next few days. Please see products issued by local National Weather Service forecast offices. 3. Swells generated by Jose are affecting Bermuda and much of the U.S. east coast, and will likely cause dangerous surf and rip current conditions for the next several days in these areas. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 39.8N 67.8W 50 KT 60 MPH 12H 21/1800Z 39.7N 67.7W 45 KT 50 MPH 24H 22/0600Z 39.8N 68.3W 45 KT 50 MPH 36H 22/1800Z 39.8N 68.8W 40 KT 45 MPH...POST-TROPICAL 48H 23/0600Z 39.6N 69.2W 35 KT 40 MPH...POST-TROPICAL 72H 24/0600Z 39.4N 69.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 25/0600Z 39.5N 68.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 26/0600Z...DISSIPATED $$ Forecaster Zelinsky

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Hurricane Maria Forecast Discussion Number 20

2017-09-21 05:00:30| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Wed Sep 20 2017 000 WTNT45 KNHC 210300 TCDAT5 Hurricane Maria Discussion Number 20 NWS National Hurricane Center Miami FL AL152017 1100 PM AST Wed Sep 20 2017 The satellite presentation is a little better organized than a few hours ago, and Maria now has a large ragged eye. However, data from an Air Force Hurricane Hunter plane indicate that the winds are still 95 kt, while the central pressure has remained unchanged oscillating near 959 mb. Even with the current favorable low-shear environment and warm ocean, it takes in general about 24 hours for the boundary layer of the hurricane to recover from the passage over high terrain, in this case Puerto Rico. In addition, the reconnaissance plane reported two wind maxima and two concentric eyewalls in the previous penetration, and it just reported that the inner one has collapsed in the last fix. This suggest that an eyewall replacement cyclone has occurred. With this complex scenario, the NHC forecast allows for some small increase in intensity as suggested by guidance and brings Maria back to category 3 status in about 24 hours. Maria continues right on track, moving toward the northwest or 310 degrees at 8 kt. The hurricane is expected to be steered north-northwestward and northward around a subtropical ridge over the Atlantic for the next 2 to 3 days. The only change to the previous forecast is a small shift to the east by the end of the forecast period as indicated by most of the track models. By then, Maria should have reached the northwestern edge of the ridge. The NHC forecast is basically on top of the multi-model consensus and very near the HFIP corrected consensus. KEY MESSAGES: 1. Maria is moving away from the northwestern coast of Puerto Rico, and strong winds and storm surge flooding should continue to subside through early Thursday. However, heavy rainfall is expected to continue, and catastrophic flash flooding is occurring on the island, especially in areas of mountainous terrain. Everyone in Puerto Rico should continue to follow advice from local officials to avoid these life-threatening flooding conditions. 2. A Hurricane Warning is in effect for the northern coast of the Dominican Republic, the Turks and Caicos Islands, and the southeastern Bahamas, where Maria is expected to bring dangerous wind, storm surge, and heavy rainfall. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 19.2N 67.9W 95 KT 110 MPH 12H 21/1200Z 19.9N 68.8W 95 KT 110 MPH 24H 22/0000Z 21.0N 70.0W 100 KT 115 MPH 36H 22/1200Z 22.3N 70.8W 100 KT 115 MPH 48H 23/0000Z 23.7N 71.5W 100 KT 115 MPH 72H 24/0000Z 26.8N 72.2W 100 KT 115 MPH 96H 25/0000Z 29.5N 72.0W 90 KT 105 MPH 120H 26/0000Z 32.0N 71.0W 80 KT 90 MPH $$ Forecaster Avila

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Tropical Storm Jose Forecast Discussion Number 63

2017-09-21 04:55:30| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Wed Sep 20 2017 000 WTNT42 KNHC 210255 TCDAT2 Tropical Storm Jose Discussion Number 63 NWS National Hurricane Center Miami FL AL122017 1100 PM AST Wed Sep 20 2017 There has been little overall change to Jose's cloud pattern since the previous advisory, as shallow convective bands remain over the northern and western portions of the circulation. Some of these bands are moving across portions of eastern Cape Cod, Martha's Vineyard, and Nantucket. The initial intensity has been reduced to 50 kt, which is supported by earlier aircraft data and a recent partial ASCAT pass that showed peak winds of 40-45 kt Water vapor imagery shows that the trough moving over eastern Canada has now passed to the northeast of Jose. As a result, the tropical storm is beginning to slow down. Jose is foreast to meander within weak steering currents over the next day or so. After that time, the cyclone is forecast to drift westward or southwestward as a ridge builds to the northwest and north of the cyclone over the weekend. There has been little change in the track guidance, and the new NHC forecast is essentially an update of the previous advisory. Cool sea surface temperatures, a drier mid-level airmass, and increasing westerly shear should result in gradual weakening during the next several days. Jose is likely to lose its remaining convection and become post-tropical in about 48 hours. The global models predict dissipation in 96 to 120 h, and the new NHC forecast follows suit. KEY MESSAGES: 1. While the center of Jose is forecast to remain offshore of the U.S. east coast, the large cyclone is expected to cause some direct impacts in portions of extreme southeastern New England during the next day or two, and a tropical storm warning remains in effect for Cape Cod, Block Island, Martha's Vineyard, and Nantucket. 2. Minor coastal flooding is possible along portions of the coast of southern New England during the next few days. Please see products issued by local National Weather Service forecast offices. 3. Swells generated by Jose are affecting Bermuda and much of the U.S. east coast and will likely cause dangerous surf and rip current conditions for the next several days in these areas. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 39.5N 68.2W 50 KT 60 MPH 12H 21/1200Z 39.6N 67.7W 45 KT 50 MPH 24H 22/0000Z 39.5N 67.7W 45 KT 50 MPH 36H 22/1200Z 39.5N 68.5W 40 KT 45 MPH 48H 23/0000Z 39.4N 69.0W 35 KT 40 MPH...POST-TROPICAL 72H 24/0000Z 39.1N 69.4W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 25/0000Z 39.0N 70.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 26/0000Z...DISSIPATED $$ Forecaster Brown

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