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Hurricane Maria Forecast Discussion Number 8

2017-09-18 10:36:09| National Hurricane Center (Atlantic)

Issued at 500 AM AST Mon Sep 18 2017 000 WTNT45 KNHC 180836 TCDAT5 Hurricane Maria Discussion Number 8 NWS National Hurricane Center Miami FL AL152017 500 AM AST Mon Sep 18 2017 Maria is maintaining a fairly circular area of intense convection with some accompanying banding features. There has also been considerable lightning occurring near the center over the past several hours, confirming the vigor of the core convection. The current intensity is set at 80 kt which is a blend of Dvorak estimates from TAFB and SAB. An Air Force Reserve Unit Hurricane Hunter aircraft is scheduled to investigate Maria in a couple of hours and will give another estimate of the strength of the hurricane. With warm waters and weak shear anticipated along the projected track of Maria, additional strengthening is forecast. According to the SHIPS-RI guidance, there is a significant probability of rapid intensification over the next day or two. The official intensity forecast is similar to the model consensus and the latest HWRF simulation. Maria is likely to be at category 3 or 4 intensity by the time it moves into the extreme northeastern Caribbean Sea. Geostationary satellite fixes and the position estimates from the Martinique radar give a motion of about 290/11 kt. A high pressure area to the north of Maria should maintain the west-northwestward motion for the next several days. Late in the forecast period, the high weakens and this should cause a turn toward the north-northwest. The official track forecast is similar to the HFIP Corrected Consensus model as well as the ECMWF and lies on the left side of the guidance suite. KEY MESSAGES: 1. Maria is likely to strengthen significantly, and is expected to be at major hurricane intensity when it affects portions of the Leeward Islands over the next few days, bringing dangerous wind, storm surge and rainfall hazards. 2. Maria is likely to affect the British and U.S. Virgin Islands and Puerto Rico by mid week as a dangerous major hurricane. Hurricane watches have been issued for the U.S. and British Virgin Islands as well as for Puerto Rico. Interests in these areas should monitor the progress of Maria and follow any advice given by local officials. FORECAST POSITIONS AND MAX WINDS INIT 18/0900Z 14.6N 59.5W 80 KT 90 MPH 12H 18/1800Z 15.1N 60.6W 90 KT 105 MPH 24H 19/0600Z 15.8N 62.0W 105 KT 120 MPH 36H 19/1800Z 16.6N 63.4W 115 KT 130 MPH 48H 20/0600Z 17.4N 64.8W 120 KT 140 MPH 72H 21/0600Z 19.0N 67.7W 115 KT 130 MPH 96H 22/0600Z 21.0N 70.4W 110 KT 125 MPH 120H 23/0600Z 23.5N 72.0W 105 KT 120 MPH $$ Forecaster Pasch

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Hurricane Otis Forecast Discussion Number 27

2017-09-18 10:33:40| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Mon Sep 18 2017 000 WTPZ45 KNHC 180833 TCDEP5 Hurricane Otis Discussion Number 27 NWS National Hurricane Center Miami FL EP152017 200 AM PDT Mon Sep 18 2017 What goes up must come down -- Otis is a classic example of what can happen with a small tropical cyclone. After rapidly intensifying earlier today, the cloud pattern has become rather poorly organized, with the center on the western edge of an irregular central dense overcast. The wind speed is reduced to 85 kt, on the high side of the latest Dvorak estimates, and this could be generous. Further weakening is likely since Otis has moved over cool SSTs and increasing shear is expected by tomorrow. Thus, rapid weakening is forecast, and the official intensity is reduced from the previous one, lying near the model consensus, although the corrected consensus models are even lower. Global models suggest Otis will degenerate into a remnant low within 2 days. Otis is still moving northward, recently at 5 kt. This northward motion should turn to the west and southwest over the next 36 hours as it is steered by a low-level ridge over the central Pacific. The global models are generally showing a stronger ridge, and the guidance has shifted farther southwest with the track of the expected remnants of the cyclone. The new NHC prediction follows the latest guidance, resulting in a faster track that is to the southwest of the previous official forecast. FORECAST POSITIONS AND MAX WINDS INIT 18/0900Z 18.5N 127.3W 85 KT 100 MPH 12H 18/1800Z 19.2N 127.5W 70 KT 80 MPH 24H 19/0600Z 19.3N 127.9W 50 KT 60 MPH 36H 19/1800Z 19.0N 128.6W 40 KT 45 MPH 48H 20/0600Z 18.2N 129.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 21/0600Z 16.5N 132.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 22/0600Z 14.7N 135.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 23/0600Z...DISSIPATED $$ Forecaster Blake

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Tropical Storm Norma Forecast Discussion Number 16

2017-09-18 10:32:09| Tropical Depression LIDIA

Issued at 300 AM MDT Mon Sep 18 2017

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Hurricane Jose Forecast Discussion Number 51

2017-09-18 04:55:18| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT Sun Sep 17 2017 000 WTNT42 KNHC 180254 TCDAT2 Hurricane Jose Discussion Number 51 NWS National Hurricane Center Miami FL AL122017 1100 PM EDT Sun Sep 17 2017 Jose's cloud pattern has transformed from one with a tight inner core to one with a large convective band over the northern semicircle that wraps around the center. This change in structure can be seen in recent microwave imagery and aircraft data that show an expansion of the radius of maximum winds. Data from NOAA and Air Force Reserve Hurricane Hunter aircraft still support an initial wind speed of 80 kt, but the minimum pressure has risen several millibars since this morning. Strong southwesterly shear and gradually decreasing sea surface temperatures along the track of Jose are expected to cause gradual weakening, however Jose is forecast to maintain hurricane intensity through 48 hours. Around that time, Jose is forecast to pass north of the north wall of the Gulf Stream and over much cooler waters, which will likely result in an additional decrease in intensity at 72 h and beyond. The NHC intensity forecast is in good agreement with the SHIPS guidance through 72 h, and closer to the global models at days 4 and 5. Jose is moving northward at about 8 kt around the western portion of a mid-level ridge over the western Atlantic. The track forecast reasoning is the same as the previous advisory. Jose should continue northward during the next day or so, then turn north- northeastward as a broad mid-latitude trough passes north of the hurricane. After the trough passes Jose's longitude in about 72 h, the cyclone will be left within weak steering currents and is expected to drift eastward, then southeastward and southward late in the forecast period. The NHC track forecast through 72 h is virtually on top of the previous advisory. The latest dynamical model guidance takes Jose a little more westward very late in the period, and the new NHC track forecast has been shifted to the left at day 5, close to the latest ECMWF ensemble mean. KEY MESSAGES: 1. While the center of Jose is currently forecast to remain offshore of the U.S. coast, the large cyclone could cause some direct impacts from Delaware northward to New England, and any deviation to the left of the NHC forecast track would increase the likelihood and magnitude of those impacts. A tropical storm watch is now in effect from the Delaware coast to southeastern Massachusetts. Interests elsewhere along the U.S. east coast from North Carolina to New England should monitor the progress of Jose through the next several days. 2. Minor to moderate coastal flooding is possible from Delaware to southern New England during the next several days. Please see products issued by local National Weather Service forecast offices. 3. Swells generated by Jose are affecting Bermuda, the Bahamas, and much of the U.S. east coast. These swells are likely to cause dangerous surf and rip current conditions for the next several days in these areas. 4. Jose will produce heavy rain as it passes near southern New England and the mid-Atlantic on Tuesday and Wednesday. Total accumulations of three to five inches are expected over eastern Long Island, southern Rhode Island, and southeast Massachusetts, including Martha's Vineyard and Nantucket. Based on the current forecast, the risk of flooding will be limited in scope. Any deviation to the left of the forecast track, however, could bring heavier and more widespread rainfall to southern New England, Long Island, New York City, and New Jersey. If this deviation were to occur, the risk of urban flash flooding and some river flooding would increase. FORECAST POSITIONS AND MAX WINDS INIT 18/0300Z 32.2N 71.6W 80 KT 90 MPH 12H 18/1200Z 33.4N 71.6W 75 KT 85 MPH 24H 19/0000Z 34.9N 71.6W 75 KT 85 MPH 36H 19/1200Z 36.6N 71.6W 70 KT 80 MPH 48H 20/0000Z 38.3N 71.0W 65 KT 75 MPH 72H 21/0000Z 40.2N 68.8W 55 KT 65 MPH 96H 22/0000Z 39.5N 68.0W 50 KT 60 MPH 120H 23/0000Z 38.5N 68.0W 45 KT 50 MPH...POST-TROPICAL $$ Forecaster Brown

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Hurricane Maria Forecast Discussion Number 7

2017-09-18 04:49:56| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Sun Sep 17 2017 000 WTNT45 KNHC 180249 TCDAT5 Hurricane Maria Discussion Number 7 NWS National Hurricane Center Miami FL AL152017 1100 PM AST Sun Sep 17 2017 Reports from an Air Force Reserve Hurricane Hunter aircraft received just after the previous advisory indicated that Maria's maximum sustained winds had increased to 70 kt. Since that time, a large central dense overcast with cloud tops colder than -80C has formed, and data from the radar on Martinique shows 60-70 percent of an eyewall is present under the overcast. Satellite intensity estimates have increased to 75 kt, and that is the initial intensity. The initial motion is 290/11. The subtropical ridge to the north is expected to steer Maria generally west-northwestward for the next 72 h, with some decrease in the forward speed. After that time, the guidance suggests that the hurricane should turn more toward the northwest as it approaches the western end of the ridge. The track guidance remains tightly clustered, and the new forecast track, which is similar to the previous track, is in best overall agreement with the HFIP corrected consensus and ECMWF models. Analyses from CIMSS at the University of Wisconsin suggest that Maria is currently experiencing light to moderate southwesterly shear. However, all indications are that the shear should diminish during the next 24-48 h, which should allow steady to rapid strengthening. The Rapid Intensification Index of the SHIPS model forecast better than a 50 percent chance of 25-30 kt of strengthening during the next 24 h, and about a 35 percent chance of 55 kt of strengthening during the next 48 h. Based on this, the intensity forecast has been increased to show Maria becoming a major hurricane in 24 h and a category 4 hurricane in 48 h. Late in the forecast period, a combination of land interaction and increasing shear should cause some weakening. The new intensity forecast is near the upper edge of the guidance in best overall agreement with the HWRF. KEY MESSAGES: 1. Maria continues to strengthen and is expected to be at major hurricane intensity when it affects portions of the Leeward Islands over the next few days, bringing dangerous wind, storm surge and rainfall hazards. Hurricane and tropical storm warnings have been issued for portions of the Leeward Islands, and these warnings will likely be extended northward and westward on Monday. 2. Maria is likely to affect the British and U.S. Virgin Islands and Puerto Rico by mid week as a dangerous major hurricane. Hurricane watches have been issued for the U.S. and British Virgin Islands and could be extended to Puerto Rico early Monday. Interests in these areas should monitor the progress of Maria and follow any advice given by local officials. FORECAST POSITIONS AND MAX WINDS INIT 18/0300Z 14.2N 58.4W 75 KT 85 MPH 12H 18/1200Z 14.7N 59.8W 85 KT 100 MPH 24H 19/0000Z 15.4N 61.2W 100 KT 115 MPH 36H 19/1200Z 16.2N 62.6W 110 KT 125 MPH 48H 20/0000Z 16.9N 63.9W 115 KT 130 MPH 72H 21/0000Z 18.5N 67.0W 120 KT 140 MPH...OVER PUERTO RICO 96H 22/0000Z 20.0N 69.5W 115 KT 130 MPH...OVER WATER 120H 23/0000Z 22.0N 71.5W 105 KT 120 MPH $$ Forecaster Beven

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