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Tropical Depression Three Forecast Discussion Number 3

2018-07-07 10:53:11| National Hurricane Center (Atlantic)

Issued at 500 AM EDT Sat Jul 07 2018 000 WTNT43 KNHC 070853 TCDAT3 Tropical Depression Three Discussion Number 3 NWS National Hurricane Center Miami FL AL032018 500 AM EDT Sat Jul 07 2018 A pair of late-arriving ASCAT passes at 0136 UTC and 0216 UTC revealed the the depression has not yet strengthened, and its circulation remains very broad. Although the larger-scale circulation of the cyclone is well-defined, it lacks an inner core, and the center of circulation consists of a wide area of light winds. The initial intensity has been held at 25 kt based primarily on the ASCAT data, and this is also supported by the latest Dvorak classifications from TAFB and SAB. While the cyclone was nearly devoid of deep convection for several hours late last night and early this morning, a broken convective band has since developed to the south of the low-level center. This could indicate that the depression is beginning to become better organized and will begin to slowly strengthen. Warm SSTs will likely allow the depression to gradually strengthen through the next 3 to 4 days, however moderate shear and the lack of an existing inner-core will likely limit the intensification rate. The intensity guidance has come into better agreement since yesterday, and now most of the models show the cyclone nearing or reaching hurricane strength. No change has been made to the NHC intensity forecast, which is now near the middle of the guidance and very close to HCCA throughout the forecast. Nighttime Proxy-Vis imagery has been very helpful in tracking the depression this morning, which has slowed down and is now estimated to be moving north-northwestward or 345/4 kt. For the first 48 h, the track models remain in fairly good agreement that the cyclone will meander off the coast of the Carolinas, as it becomes trapped in the light steering flow between a cold front passing to the north and the subtropical ridge to the east. Beyond that time, there has been a significant change in the track models, all of which now depict a much faster northeastward motion beginning on Tuesday as the cyclone recurves ahead of a mid-level trough approaching from the northwest. Although the NHC track forecast has been adjusted to show a faster motion at day 4 and 5, it is now much slower than all of the global models in an effort to maintain continuity from our earlier forecasts. If this trend continues, larger changes will need to be made to the track forecast in future advisories. Most of the guidance continues to suggest that the tropical-storm-force winds associated with the cyclone will occur primarily to the east of the cyclone's center well away from the U.S. coast. Therefore, no watches or warnings are required for the U.S coast at this time, however, interests along the North Carolina coast should monitor the progress of this system. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 33.2N 74.6W 25 KT 30 MPH 12H 07/1800Z 33.6N 74.8W 30 KT 35 MPH 24H 08/0600Z 33.8N 74.5W 35 KT 40 MPH 36H 08/1800Z 33.9N 74.0W 40 KT 45 MPH 48H 09/0600Z 34.0N 73.6W 45 KT 50 MPH 72H 10/0600Z 34.5N 72.5W 55 KT 65 MPH 96H 11/0600Z 37.0N 69.0W 65 KT 75 MPH 120H 12/0600Z 41.0N 63.5W 65 KT 75 MPH $$ Forecaster Zelinsky

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Hurricane Beryl Forecast Discussion Number 7

2018-07-07 04:40:41| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Fri Jul 06 2018 000 WTNT42 KNHC 070240 TCDAT2 Hurricane Beryl Discussion Number 7 NWS National Hurricane Center Miami FL AL022018 1100 PM AST Fri Jul 06 2018 While Beryl continues to produce a cluster of convection near the center, the system appears a little less organized than earlier. In addition, there are no recent microwave overpasses showing an eye under the overcast. The various satellite intensity estimates are unchanged since the previous advisory, so the initial intensity is held at 70 kt. However, it is possible that this is a bit generous given the observed decay of the cloud pattern. The hurricane continues moving westward or 280/12. The track guidance insists that a turn toward the west-northwest and an increase in forward speed should occur in the next 12-24 h as Beryl continues to be steered by the strong subtropical ridge to the north. The new NHC forecast again follows this scenario, but it lies on the south side of the guidance envelope due to current trends and the overall northeast bias that the track guidance has shown so far. The new NHC track has the center near the Lesser Antilles in about 48 h, over the north central Caribbean Sea in about 72 h, and near eastern Cuba in about 96 h - if the system actually survives that long. Beryl is expected to remain in a light vertical wind shear environment for 36 h or so, then encounter steadily increasing westerly shear as it moves into the Caribbean Sea. The intensity guidance forecasts less strengthening during the time of favorable conditions than previously, and based on this first part of the intensity forecast is lowered slightly from that of the previous advisory. Steady to rapid weakening should occur over the eastern Caribbean due to stronger shear, and the current forecast has Beryl weakening to a tropical wave after 96 h. An alternative scenario, supported by the large-scale models, is that Beryl weakens to a tropical wave near the 72-h point. The technical issue with the NHC wind speed probabilities text products at land locations has been resolved. The wind speed probability values provided in the text product, the graphics on the the NHC website at hurricanes.gov, and the publicly disseminated grid files will all correctly reflect the reduced probabilities over land. Key Messages: 1. Beryl is forecast to be a hurricane when it moves through the Lesser Antilles Sunday night or Monday, and the chance of some islands receiving direct impacts from wind and rainfall are increasing. Hurricane and tropical storm watches are in effect for some of the countries in the Lesser Antilles, and additional watches could be required for other islands early Saturday. 2. Due to its very small size, there is greater-than-usual uncertainty in the analysis of Beryl's current intensity, and confidence in the official intensity forecast is also lower than normal. Rapid changes in intensity, both up and down, that are difficult to predict are possible during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 10.9N 48.9W 70 KT 80 MPH 12H 07/1200Z 11.3N 50.6W 75 KT 85 MPH 24H 08/0000Z 12.3N 53.5W 75 KT 85 MPH 36H 08/1200Z 13.3N 56.8W 75 KT 85 MPH 48H 09/0000Z 14.4N 60.6W 70 KT 80 MPH 72H 10/0000Z 16.5N 68.5W 50 KT 60 MPH 96H 11/0000Z 19.5N 76.5W 35 KT 40 MPH 120H 12/0000Z...DISSIPATED $$ Forecaster Beven

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Tropical Depression Three Forecast Discussion Number 2

2018-07-07 04:37:10| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT Fri Jul 06 2018 000 WTNT43 KNHC 070237 TCDAT3 Tropical Depression Three Discussion Number 2 NWS National Hurricane Center Miami FL AL032018 1100 PM EDT Fri Jul 06 2018 The depression has not become any better organized since the previous advisory. Deep convection has decreased a little near the center, but some banding features are still evident on the south side of the circulation. The initial intensity is held at 25 kt, in general agreement with the Dvorak classifications from TAFB and SAB, and automated values from CIMSS at the University of Wisconsin. The system is currently over the warm Gulf Stream waters, and it is expected to remain over this current during the next several days. These favorable oceanic conditions combined with light to moderate wind shear and a fair amount of moisture near the system should allow for gradual intensification. The SHIPS model is the most aggressive aid and shows the cyclone becoming a hurricane in about 3 days with additional strengthening thereafter. On the other hand, the HMON model shows no strengthening through the period. The NHC intensity forecast continues to lean toward the high end of the guidance due to the conducive environmental conditions for strengthening. The depression is moving north-northwestward at 5 kt steered by the flow on the western periphery of a subtropical ridge. A slow north-northwest to north motion is expected during the next 24 hours while the steering pattern holds. However, by Saturday night, the steering currents are forecast to collapse and the cyclone will likely drift eastward or southeastward on Sunday and Monday. Thereafter, a shortwave trough is anticipated to approach the system and it should finally sweep the cyclone northeastward well east of the U.S. coast beginning on Tuesday. The latest HWRF model run brings the system inland over the southeastern U.S., but this model is an outlier, and the remainder of the guidance shows a track well offshore of the U.S. coast. The NHC track forecast is a tad to the east of the previous one to come into better agreement with the latest consensus models. Most of the guidance suggests that the tropical-storm-force winds associated with the cyclone will occur primarily to the east of the cyclone's center well away from the U.S. coast. Therefore, no watches or warnings are required for the U.S coast at this time, however, interests along the North Carolina coast should monitor the progress of this system. The technical issue with the NHC wind speed probability text product at land locations has been resolved. The wind speed probability values provided in the text product, the graphics on the NHC website at hurricanes.gov, and the publicly disseminated grid files will all correctly reflect the reduced probabilities over land. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 32.6N 74.1W 25 KT 30 MPH 12H 07/1200Z 33.2N 74.4W 30 KT 35 MPH 24H 08/0000Z 33.7N 74.5W 35 KT 40 MPH 36H 08/1200Z 33.7N 74.2W 40 KT 45 MPH 48H 09/0000Z 33.6N 73.7W 45 KT 50 MPH 72H 10/0000Z 33.6N 73.4W 50 KT 60 MPH 96H 11/0000Z 34.7N 71.6W 65 KT 75 MPH 120H 12/0000Z 38.0N 67.0W 65 KT 75 MPH $$ Forecaster Cangialosi

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Hurricane Beryl Forecast Discussion Number 6

2018-07-06 22:41:06| National Hurricane Center (Atlantic)

Issued at 500 PM AST Fri Jul 06 2018 000 WTNT42 KNHC 062041 TCDAT2 Hurricane Beryl Discussion Number 6 NWS National Hurricane Center Miami FL AL022018 500 PM AST Fri Jul 06 2018 Beryl has lost its tiny pinhole eye from earlier this morning, but the system continues to produce a compact area of deep convection near the center. Since Dvorak estimates have changed little from six hours ago, the initial intensity will remain 70 kt for this advisory. Global model fields continue to show an upper-level anticyclone moving westward in tandem with the hurricane for the next 48 hours or so, which would keep the vertical shear low enough to allow for some intensification. After 48 hours, however, the upper-level pattern is expected to evolve to southerlies or westerlies over the system, which would increase the shear and cause weakening. Given the seemingly favorable environment for the next 2 days, the NHC intensity forecast continues to lie along the upper bound of the guidance. After 48 hours, the intensity forecast is closer to the HCCA model and the intensity consensus. It bears repeating that the intensity forecast remains highly uncertain given Beryl's small size, and the cyclone could just as easily dissipate into an open wave sooner than indicated in the official forecast. The hurricane is moving westward, or 270/13 kt, and may have actually lost a little latitude today. Given the more southerly initial position, the track guidance suite has shifted south accordingly, and the new NHC track has been adjusted in that direction as well, lying between the model consensus aids and the southern edge of the solutions. Additional southward adjustments to the forecast track are likely if Beryl does not gain latitude soon. Given the larger-than-normal uncertainties associated with Beryl's future track and intensity, the governments and meteorological services of several of the countries in the Lesser Antilles have elected to issue tropical storm or hurricane watches for their islands, sooner than the typical 48-hour threshold for the onset of tropical-storm-force winds. Please refer to products issued by the meteorological services of those respective countries for additional information. Due to a technical issue, the wind speed probability values at land locations in the wind speed probability text product are too high and do not reflect reduced probabilities that are expected over land. The wind speed probability values provided in the graphics on the NHC website at hurricanes.gov, and in the publicly disseminated grid files do correctly reflect the reduced probabilities over land. As a result, users should refer to the NHC website graphics and gridded products instead of the text product for the most accurate wind speed probability values until this problem is resolved. Key Messages: 1. Beryl is expected to be a hurricane when it moves through the Lesser Antilles Sunday night or Monday, and the chance of some islands receiving direct impacts from wind and rainfall are increasing. Hurricane and tropical storm watches have been issued by some of the countries in the Lesser Antilles, and additional watches could be required for other islands tonight or early Saturday. 2. Due to its very small size, there is greater-than-usual uncertainty in the analysis of Beryl's current intensity, and confidence in the official intensity forecast is also lower than normal. Rapid changes in intensity, both up and down, that are difficult to predict are possible during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 06/2100Z 10.6N 47.8W 70 KT 80 MPH 12H 07/0600Z 11.1N 49.4W 75 KT 85 MPH 24H 07/1800Z 11.9N 51.8W 80 KT 90 MPH 36H 08/0600Z 12.9N 54.7W 80 KT 90 MPH 48H 08/1800Z 13.8N 58.2W 80 KT 90 MPH 72H 09/1800Z 16.1N 66.7W 55 KT 65 MPH 96H 10/1800Z 18.5N 75.0W 40 KT 45 MPH 120H 11/1800Z...DISSIPATED $$ Forecaster Berg

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Tropical Depression Three Forecast Discussion Number 1

2018-07-06 22:39:38| National Hurricane Center (Atlantic)

Issued at 500 PM EDT Fri Jul 06 2018 000 WTNT43 KNHC 062039 TCDAT3 Tropical Depression Three Discussion Number 1 NWS National Hurricane Center Miami FL AL032018 500 PM EDT Fri Jul 06 2018 The area of low pressure located a few hundred miles southeast of the North Carolina coast has developed enough deep convection with a well-defined circulation to be classified as a tropical depression. This is supported by a Dvorak T-number of 2.0 from TAFB, and an earlier ASCAT pass with 25-kt winds, which is the initial intensity assigned to the depression. Given that the system is moving over warm waters and in a low-shear environment, gradual strengthening is indicated, and the NHC forecast shows the depression becoming a tropical storm on Saturday. Additional intensification could occur by the end of the forecast period when the cyclone moves northeastward away from the U.S coast and interacts with a mid-level trough. The intensity forecast is very close to the SHIPS model and the Corrected Consensus HCCA. The depression is moving toward the north-northwest or 335 degrees at about 4 knots. The tropical cyclone is currently located on the southwestern edge of the subtropical ridge, and this weak flow pattern should keep the depression on the same slow track for the next 24 hours or so. After that time, the steering currents are expected to collapse, and the cyclone should begin to meander for a couple of days well off the coast of North Carolina. Then a mid-level trough is expected to approach from the west and force the system on a northeastward track. Most of the guidance suggests that the tropical-storm-force winds associated with the cyclone will occur in the eastern quadrant well away from the U.S. coast. On this basis, no watches or warnings are required for the U.S coast at this time, however, interests along the North Carolina coast should monitor the progress of this system. Due to a technical issue, the wind speed probability values at land locations in the wind speed probability text product are too high and do not reflect reduced probabilities that are expected over land. The wind speed probability values provided in the graphics on the NHC website at hurricanes.gov, and in the publicly disseminated grid files do correctly reflect the reduced probabilities over land. As a result, users should refer to the NHC website graphics and gridded products instead of the text product for the most accurate wind speed probability values until this problem is resolved. FORECAST POSITIONS AND MAX WINDS INIT 06/2100Z 32.2N 73.8W 25 KT 30 MPH 12H 07/0600Z 32.9N 74.3W 30 KT 35 MPH 24H 07/1800Z 33.7N 74.5W 35 KT 40 MPH 36H 08/0600Z 34.0N 74.3W 40 KT 45 MPH 48H 08/1800Z 34.0N 74.0W 45 KT 50 MPH 72H 09/1800Z 33.5N 73.7W 50 KT 60 MPH 96H 10/1800Z 33.5N 73.7W 65 KT 75 MPH 120H 11/1800Z 36.5N 69.5W 70 KT 80 MPH $$ Forecaster Avila

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