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Tropical Storm Beryl Forecast Discussion Number 10

2018-07-07 22:32:54| National Hurricane Center (Atlantic)

Issued at 500 PM AST Sat Jul 07 2018 000 WTNT42 KNHC 072032 TCDAT2 Tropical Storm Beryl Discussion Number 10 NWS National Hurricane Center Miami FL AL022018 500 PM AST Sat Jul 07 2018 Beryl has not changed much in appearance since this morning. The storm still has a tight low-level circulation with all of the deep convection displaced to the east and southeast of the center. Scatterometer data missed the circulation this morning, and we still do not have a good handle on Beryl's maximum winds. Dvorak CI numbers are now 3.0 from both TAFB and SAB, so the initial intensity will be lowered to 45 kt, which could still be generous. Beryl seems to be accelerating sooner than initially anticipated, and the 12-hour motion is now west-northwestward, or 295/15 kt. Not only is the cyclone moving a little faster now, but the track guidance is also showing a faster future motion than it had been indicating. The overall guidance envelope has also shifted slightly northward. Therefore, the new NHC track forecast is a little faster than the previous forecast to be closer to the multi-model consensus aids, and it has been shifted ever-so-slightly to the north as well. With the low-level easterlies around Beryl increasing, and the cyclone expected to run into upper-level westerlies in about 24 hours, the deep-layer shear is forecast to strengthen over the next couple of days. This increased shear and nearby dry air will likely cause Beryl to continue weakening, and the updated NHC intensity forecast now shows the cyclone weakening to a tropical depression by the time it reaches the eastern Caribbean Sea, if not sooner. Beryl is then likely to open up into a trough shortly after 48 hours, which is shown by all the global models. It should be noted that despite the expected weakening, some of the global models show deep convection reigniting due to upper-level divergence to the east of a trough, and even as an open wave the system will still likely produce gusty winds and locally heavy rainfall across the Leeward Islands and portions of the Greater Antilles during the next several days. Key Messages: 1. Beryl has continued to weaken today, but there is still a chance of some islands in the Lesser Antilles receiving direct impacts from wind and rainfall, where tropical storm warnings and watches remain in effect. Gusty winds and locally heavy rainfall will also be possible across the remainder of the Leeward Islands, the Virgin Islands, and Puerto Rico through early next week. 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. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 12.7N 52.7W 45 KT 50 MPH 12H 08/0600Z 13.4N 55.0W 40 KT 45 MPH 24H 08/1800Z 14.6N 58.5W 35 KT 40 MPH 36H 09/0600Z 15.9N 62.4W 35 KT 40 MPH 48H 09/1800Z 17.3N 66.3W 30 KT 35 MPH 72H 10/1800Z...DISSIPATED $$ Forecaster Berg

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Tropical Depression Three Forecast Discussion Number 5

2018-07-07 22:32:23| National Hurricane Center (Atlantic)

Issued at 500 PM EDT Sat Jul 07 2018 000 WTNT43 KNHC 072032 TCDAT3 Tropical Depression Three Discussion Number 5 NWS National Hurricane Center Miami FL AL032018 500 PM EDT Sat Jul 07 2018 An Air Force reconnaissance aircraft investigated the depression a few hours ago and found that the circulation is still somewhat elongated with a minimum pressure of 1015 mb. The plane measured flight-level winds which support an initial intensity of 30 kt. These winds were confined to a convective band south of the center. The satellite presentation has not improved very much since the morning advisory. The cyclone will remain over warm waters and in a relatively low-shear environment for the next 2 to 3 days. Based on these conditions, the NHC forecast calls for gradual strengthening, and the depression is expected to become a tropical storm within the next 12 hours or so. Additional intensification is anticipated when the cyclone moves toward the northeast over the open Atlantic as indicated by most of the models. The cyclone will most likely begin to acquire extratropical characteristics over cold waters by the end of the forecast period. The depression continues to be embedded within very weak steering currents, and little motion is anticipated for the next 2 days. After that time, the cyclone will be steered toward the northeast with increasing forward speed within the southwesterly flow ahead of an approaching mid-level trough. Guidance continues to clearly indicate the cyclone's slow drift during the next 2 days, and unanimously forecast the cyclone to accelerate to the northeast thereafter. The NHC forecast continues to be in the middle of the guidance envelope, and very closely follows the multi-model consensus. Guidance continues to suggest that the cyclone will not approach the coast and that the forecast tropical-storm-force winds will not reach the U.S. coast. On this basis, no watches or warnings are required at this time, however, interests along the North Carolina coast should monitor the progress of the system. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 32.9N 75.3W 30 KT 35 MPH 12H 08/0600Z 33.0N 75.3W 40 KT 45 MPH 24H 08/1800Z 33.0N 74.7W 45 KT 50 MPH 36H 09/0600Z 32.9N 74.1W 50 KT 60 MPH 48H 09/1800Z 33.0N 73.9W 55 KT 65 MPH 72H 10/1800Z 34.5N 71.5W 65 KT 75 MPH 96H 11/1800Z 40.0N 63.5W 60 KT 70 MPH 120H 12/1800Z 48.0N 54.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Avila

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Tropical Depression Three Forecast Discussion Number 4

2018-07-07 16:50:16| National Hurricane Center (Atlantic)

Issued at 1100 AM EDT Sat Jul 07 2018 000 WTNT43 KNHC 071450 TCDAT3 Tropical Depression Three Discussion Number 4 NWS National Hurricane Center Miami FL AL032018 1100 AM EDT Sat Jul 07 2018 Although the convection has increased this morning and it seems a little better organized, surface observations and satellite intensity estimates from TAFB and SAB indicate that the winds remain at 25 kt. An Air Force reconnaissance aircraft will check the depression later this morning, so we will have more information about the intensity and structure of the depression later today. The cyclone will remain over warm waters and in a relatively low-shear environment for the next 2 to 3 days. Based on these conditions, the NHC forecast calls for gradual strengthening at a rate very close to the HCCA corrected consensus model. The cyclone will most likely begin to acquire extratropical characteristics by the end of the forecast period. The depression is embedded within very weak steering currents, and little motion is anticipated for the next 2 days. After that time, the cyclone will be steered toward the northeast with increasing forward speed within the southwesterly flow ahead of an approaching mid-level trough. Guidance clearly indicates the cyclone's slow motion during the next 2 days, and unanimously forecast the cyclone to accelerate to the northeast thereafter. The NHC forecast is in the middle of the guidance envelope, and very closely follows the multi-model consensus. Guidance continues to suggest that the forecast tropical-storm-force winds associated with the cyclone will not reach the U.S. coast. On this basis, no watches or warnings are required at this time, however, interests along the North Carolina coast should monitor the progress of the depression. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 33.1N 74.8W 25 KT 30 MPH 12H 08/0000Z 33.4N 74.8W 30 KT 35 MPH 24H 08/1200Z 33.5N 74.2W 40 KT 45 MPH 36H 09/0000Z 33.5N 73.5W 45 KT 50 MPH 48H 09/1200Z 33.5N 72.5W 50 KT 60 MPH 72H 10/1200Z 35.5N 70.0W 50 KT 60 MPH 96H 11/1200Z 39.5N 64.0W 65 KT 75 MPH 120H 12/1200Z 47.0N 54.5W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Avila

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Tropical Storm Beryl Forecast Discussion Number 9

2018-07-07 16:47:49| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Sat Jul 07 2018 000 WTNT42 KNHC 071447 TCDAT2 Tropical Storm Beryl Discussion Number 9 NWS National Hurricane Center Miami FL AL022018 1100 AM AST Sat Jul 07 2018 Beryl's small size was always going to make it prone to wild and unpredictable fluctuations in intensity, and that appears to have come to fruition this morning. The cyclone's low-level center is now completely exposed with all associated deep convection displaced to the east and southeast. Dvorak estimates from TAFB and SAB have decreased accordingly, and the initial intensity is set at 55 kt, with Beryl being downgraded to a tropical storm. Even though upper-level winds over the system remain light, and upper-level cloud motions are still from east to west, strengthening low-level flow is likely leading to an increase in the deep-layer westerly shear. In fact, analyses from UW-CIMSS indicate that about 15 kt of westerly shear is now over the system. The shear and a very dry ambient environment have likely caused the small and fragile cyclone to suddenly weaken. Since the low-level flow is expected to increase further, and Beryl will be running into upper-level westerlies in 36-48 hours, the shear is only expected to become more hostile. This will make it extremely difficult for Beryl to become more organized again, and its chances of being a hurricane before reaching the Lesser Antilles have decreased significantly. The updated NHC intensity forecast has been lowered from the previous advisory, and now keeps Beryl as a tropical storm through the forecast period. The forecast intensities could still be a little high, and this prediction will remain low confidence until we get a better handle on Beryl's initial intensity. Even though a 72-hour forecast is provided, it is entirely possible that Beryl will open up into a trough over the eastern Caribbean Sea before that time. Regardless of whether the system has a closed circulation, it is likely to continue producing strong gusty winds and locally heavy rainfall over portions of the Greater Antilles next week. Beryl is now gaining more latitude and has an initial motion of 295/12 kt. The cyclone is still expected to accelerate toward the west-northwest during the next several days, and the track guidance remains tightly clustered through the forecast period. The new NHC track forecast has been shifted slightly northward due to Beryl's recent northwestward jog, and it lies relatively close to the HCCA guidance. Key Messages: 1. Beryl is no longer forecast to be near hurricane strength when it approaches the Lesser Antilles Sunday night or Monday, but the chance of some islands receiving direct impacts from wind and rainfall continues. Tropical storm warnings and watches are in effect for some of the countries in the Lesser Antilles, and additional watches or warnings could be required for other islands later today. 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 07/1500Z 12.1N 51.1W 55 KT 65 MPH 12H 08/0000Z 12.6N 52.9W 50 KT 60 MPH 24H 08/1200Z 13.6N 56.0W 50 KT 60 MPH 36H 09/0000Z 14.8N 59.6W 50 KT 60 MPH 48H 09/1200Z 15.9N 63.6W 45 KT 50 MPH 72H 10/1200Z 18.3N 71.7W 35 KT 40 MPH...INLAND 96H 11/1200Z...DISSIPATED $$ Forecaster Berg

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Hurricane Beryl Forecast Discussion Number 8

2018-07-07 10:59:13| National Hurricane Center (Atlantic)

Issued at 500 AM AST Sat Jul 07 2018 000 WTNT42 KNHC 070859 TCDAT2 Hurricane Beryl Discussion Number 8 NWS National Hurricane Center Miami FL AL022018 500 AM AST Sat Jul 07 2018 Although there has been no recent microwave imagery to help examine the inner-core structure of Beryl, the small tropical cyclone appears to have lost some organization since yesterday afternoon. Shortwave GOES-16 infrared imagery suggests that the center is near the northwestern portion of the small convective mass. Dvorak data T-numbers from both TAFB and SAB have dropped to T3.5 while CI numbers support keeping Beryl a 65-kt hurricane, but this could be generous. The hurricane seems to have finally gained some latitude and the initial motion estimate is west-northwest or 285/12 kt. Beryl is located to the south of a strong mid-level ridge that is anchored over the west-central Atlantic. This should keep the cyclone on a general west-northwestward heading with some increase in forward speed over the next few days. The track models did not change much this cycle and only slight adjustments were made to the previous NHC forecast. The official forecast is once again along the southern side of the guidance envelope, in best agreement with the UKMET and FSSE models. Beryl is expected to remain in a light vertical wind shear environment today, but an increase in westerly shear is expected on Sunday, and the shear is forecast to become quite strong as Beryl moves over the eastern Caribbean early next week. As a result, the new NHC intensity forecast calls for little change in strength during the next 24-36 h, but predicts steady weakening after that time. The updated intensity forecast is lower than the previous advisory due to the lower initial intensity and less bullish intensity guidance. The new NHC forecast also shows Beryl degenerating into an open trough in 3 to 4 days, which is in good agreement within the global models that all predict this to occur while the system moves across the eastern Caribbean. Regardless of whether the system has a closed circulation, it is likely to continue producing strong gusty winds and locally heavy rainfall over portions of the Greater Antilles next week. Key Messages: 1. Beryl is forecast to be near hurricane strength when it approaches the Lesser Antilles Sunday night or Monday, and the chance of some islands receiving direct impacts from wind and rainfall continue to increase. 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 today. 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 07/0900Z 11.1N 49.8W 65 KT 75 MPH 12H 07/1800Z 11.7N 51.6W 65 KT 75 MPH 24H 08/0600Z 12.6N 54.4W 65 KT 75 MPH 36H 08/1800Z 13.7N 57.9W 60 KT 70 MPH 48H 09/0600Z 14.8N 61.6W 55 KT 65 MPH 72H 10/0600Z 17.2N 70.0W 45 KT 50 MPH 96H 11/0600Z...DISSIPATED $$ Forecaster Brown

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