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Tropical Storm Maria Forecast Discussion Number 3

2017-09-17 04:59:05| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Sat Sep 16 2017 000 WTNT45 KNHC 170258 TCDAT5 Tropical Storm Maria Discussion Number 3 NWS National Hurricane Center Miami FL AL152017 1100 PM AST Sat Sep 16 2017 Maria has become a little better organized this evening, with satellite imagery showing the formation of a small convective area near the center that may reflect the formation of an inner wind core. However, this has not yet resulted in intensification, as various subjective and objective satellite intensity estimates remain about 45 kt. The longer-term initial motion is 280/14, while recent satellite imagery suggests the system may be turning a little more to the right. A mid-level ridge to the north of the cyclone is expected to gradually weaken through the forecast period, which would allow Maria to move generally west-northwestward with a decrease in forward speed during the next five days. The track guidance is tightly clustered, and the new forecast track is nudged only slightly to the left of the previous track based on the initial location. The forecast continues to take the core of Maria near the Leeward Islands in 48 to 72 hours, close to the Virgin Islands and Puerto Rico in about 96 hr, and near eastern Hispaniola at about 120 h. Maria is expected to remain in an environment of good moisture, light shear, and warm sea surface temperatures for at least the next 4 days. This should result in steady to rapid intensification. The new intensity forecast is similar to the previous forecast in calling for Maria to become a hurricane in 24 h and a major hurricane in 72 h, and it lies at the upper edge of the intensity guidance. However, rapid intensification is a distinct possibility, and it would be no surprise if Maria got significantly stronger than currently forecast. KEY MESSAGES: 1. Maria is expected to strengthen and affect portions of the Leeward Islands as a hurricane early next week, bringing dangerous wind, storm surge and rainfall hazards. Hurricane and tropical storm watches have been issued for portions of the Lesser Antilles, and additional watches will likely be issued on Sunday. 2. Maria could also affect the British and U.S. Virgin Islands and Puerto Rico by mid week as a dangerous major hurricane, and hurricane watches could be issued for these islands as early as Sunday. Interests in these areas should monitor the progress of Maria and follow any advice given by local officials. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 12.5N 53.7W 45 KT 50 MPH 12H 17/1200Z 13.1N 55.7W 55 KT 65 MPH 24H 18/0000Z 13.9N 57.6W 65 KT 75 MPH 36H 18/1200Z 14.6N 59.2W 75 KT 85 MPH 48H 19/0000Z 15.3N 60.7W 90 KT 105 MPH 72H 20/0000Z 16.5N 63.5W 105 KT 120 MPH 96H 21/0000Z 18.0N 66.5W 110 KT 125 MPH...COAST OF PUERTO RICO 120H 22/0000Z 19.5N 69.0W 100 KT 115 MPH...OVER WATER $$ Forecaster Beven

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Tropical Storm Lee Forecast Discussion Number 9

2017-09-17 04:50:25| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Sat Sep 16 2017 000 WTNT44 KNHC 170250 TCDAT4 Tropical Storm Lee Discussion Number 9 NWS National Hurricane Center Miami FL AL142017 1100 PM AST Sat Sep 16 2017 Lee has a classic shear pattern appearance in satellite imagery this evening, with the center on the northern edge of a large convective burst due to the effects of 15-20 kt of northwesterly vertical shear. Two recent ASCAT overpasses indicate that the maximum winds are about 35 kt in the southern semicircle, with no winds of tropical-storm-force in the northern semicircle. The initial intensity of 35 kt is based on the scatterometer data. The initial motion is 275/7. Lee is moving along the south side of a weak mid-level ridge. After about 24 h, the ridge is expected to weaken and allow Lee to turn west-northwestward, a motion that should continue through the forecast period. The new track forecast is similar to the previous forecast and lies mainly between the ECMWF and the HFIP corrected consensus models. Lee is expected to encounter strong upper-level winds through the forecast period, with vertical shear values likely to exceed 30 kt after 48 h. While some short-term spin up due to convective bursts cannot be ruled out, overall the environment is not favorable for significant strengthening. Indeed, the intensity guidance calls for gradual weakening, and the GFS and ECMWF models forecast the cyclone to completely dissipate by 120 h. The new intensity forecast is weaker than the previous forecast and now calls for Lee to degenerate to a remnant low by 96 h. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 12.8N 34.9W 35 KT 40 MPH 12H 17/1200Z 12.9N 36.0W 35 KT 40 MPH 24H 18/0000Z 13.1N 37.5W 35 KT 40 MPH 36H 18/1200Z 13.7N 39.2W 35 KT 40 MPH 48H 19/0000Z 14.4N 41.0W 30 KT 35 MPH 72H 20/0000Z 16.0N 44.5W 30 KT 35 MPH 96H 21/0000Z 17.5N 48.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 22/0000Z 19.0N 52.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Beven

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Tropical Storm Norma Forecast Discussion Number 11

2017-09-17 04:44:30| Tropical Depression LIDIA

Issued at 900 PM MDT Sat Sep 16 2017

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Tropical Storm Otis Forecast Discussion Number 22

2017-09-17 04:42:01| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Sat Sep 16 2017 000 WTPZ45 KNHC 170241 TCDEP5 Tropical Storm Otis Discussion Number 22 NWS National Hurricane Center Miami FL EP152017 800 PM PDT Sat Sep 16 2017 Convection has increased near the center of Otis since the last advisory, and an AMSR-2 pass around 2030 UTC indicated that the tropical storm was beginning to develop an inner-core. A consensus of Dvorak current intensity estimates from TAFB and SAB supports raising the initial intensity to 40 kt. Otis is expected to remain over moderate SSTs and within a low-shear environment for the next 24 to 36 h. Given that the storm finally appears to be supporting persistent deep convection near the center, at least a little more intensification seems likely, and this is supported by the statistical-dynamical models. After about 48 h, lower SSTs and some increase in shear should cause the cyclone to gradually weaken. The new intensity forecast is a little higher than the previous forecast for the first 48 h, but still shows Otis becoming a remnant low by 96 h. Otis has continued to move very slowly westward, and has not yet turned northward, toward a weakness in the subtropical ridge. All of the global models still indicate that this turn is imminent, but regardless of when exactly it occurs, little overall movement is expected for the next 72 h. Beyond that time, a faster west-southwest track is still anticipated as the remnants of Otis become steered primarily by the low-level tradewinds. Little change overall has been made to the track forecast. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 15.9N 127.3W 40 KT 45 MPH 12H 17/1200Z 16.3N 127.7W 40 KT 45 MPH 24H 18/0000Z 17.0N 127.8W 45 KT 50 MPH 36H 18/1200Z 17.9N 127.8W 45 KT 50 MPH 48H 19/0000Z 18.3N 128.0W 40 KT 45 MPH 72H 20/0000Z 18.3N 128.8W 35 KT 40 MPH 96H 21/0000Z 17.1N 131.4W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 22/0000Z 16.5N 134.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Zelinsky

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Hurricane Jose Forecast Discussion Number 47

2017-09-17 04:40:01| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT Sat Sep 16 2017 000 WTNT42 KNHC 170239 TCDAT2 Hurricane Jose Discussion Number 47 NWS National Hurricane Center Miami FL AL122017 1100 PM EDT Sat Sep 16 2017 Jose's cloud pattern has not changed much since the previous advisory. The center is embedded within a fairly symmetric CDO but deep convection and the overall cloud shield is elongated northeastward due to some westerly shear. The latest satellite intensity estimates from TAFB, SAB, and UW/CIMSS range from 60 kt to 77 kt. Since the earlier aircraft data suggest that Jose's intensity was near the midpoint of this range, a 70-kt initial wind speed is maintained for this advisory. The satellite fixes are little to the east of the previously estimated positions, but given the westerly shear the surface center is likely located a little west of these, resulting in an initial motion estimate of 360/5 kt. Jose is forecast to move northward at a slightly faster pace around the western portion of a subtropical ridge over the next few days. After that time, Jose is predicted to turn northeastward, then eastward as it enters the mid-latitude westerly flow. The 18Z GFS has trended a bit slower at days 4 and 5, so the NHC track forecast has been adjusted accordingly. The ECMWF and UKMET models remain to the west of the official forecast and it is still possible that Jose will track somewhat closer to the U.S. east coast than indicated here. Jose still has a small window of opportunity to strengthen before westerly shear increases, however, most of the intensity guidance now calls for gradual weakening to begin within 12-24 hours. Decreasing sea surface temperatures after 72 hours should cause an additional decrease in intensity later in the period. The NHC intensity prediction is near the higher statistical guidance during the first couple of days, and near the global model guidance later in the period. KEY MESSAGES: 1. The center of Jose is forecast to pass well east of the North Carolina coast on Monday, and tropical-storm-force winds are currently expected to remain offshore of the North Carolina Outer Banks. However, an additional increase in the size of the storm or a westward adjustment in the track forecast could bring tropical storm conditions closer to the Outer Banks, and interests there should monitor the progress of Jose through Monday. 2. While Jose is currently forecast to remain offshore of the U.S. coast from Virginia northward to New England, the large cyclone could cause some direct impacts to these areas and any deviation to the left of the NHC forecast track would increase the likelihood and magnitude of those impacts. Interests along the U.S. east coast from Virginia to New England should monitor the progress of Jose through the next several days. 3. Swells generated by Jose are affecting Bermuda, the Bahamas, the northern coasts of Hispaniola and Puerto Rico, 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. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 29.2N 71.8W 70 KT 80 MPH 12H 17/1200Z 30.0N 71.7W 75 KT 85 MPH 24H 18/0000Z 31.4N 71.5W 70 KT 80 MPH 36H 18/1200Z 32.9N 71.4W 70 KT 80 MPH 48H 19/0000Z 34.4N 71.3W 65 KT 75 MPH 72H 20/0000Z 37.7N 70.5W 60 KT 70 MPH 96H 21/0000Z 40.2N 67.5W 55 KT 65 MPH 120H 22/0000Z 40.5N 64.0W 50 KT 60 MPH $$ Forecaster Brown

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