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Tropical Storm Kristy Forecast Discussion Number 10
2018-08-09 10:44:48| National Hurricane Center (East Pacific)
Issued at 200 AM PDT Thu Aug 09 2018 158 WTPZ43 KNHC 090844 TCDEP3 Tropical Storm Kristy Discussion Number 10 NWS National Hurricane Center Miami FL EP132018 200 AM PDT Thu Aug 09 2018 Deep convection has continued to increase near and to the north and east of Kristy's center, and cirrus outflow has expanded some in all quadrants. Satellite intensity estimates supported an intensity of 40 kt at 0600 UTC, but the recent increase in convection, along with a Dvorak estimate of T3.0/45 kt from TAFB and and a UW-CIMSS ADT estimate of T2.9/43 kt, justify increasing the advisory intensity to 45 kt. Kristy has turned to north-northwest and is now moving 345/05 kt. The cyclone is expected to turn toward the north later today, followed by a motion toward the north-northeast or northeast in the 24-48 h time period as Kristy and much larger Tropical Storm John undergo some weak binary interaction. However, the two cyclones separate by 72 h as John weakens over cold waters and its influence on Kristy diminishes, resulting in a turn to the north. By 96 h and beyond, Kristy will also be located over much colder water and is expected to have degenerated into a shallow remnant low pressure, becoming steered more westward by the deep-layer easterly trade wind flow. There remains considerable divergence among the global and regional hurricane models, with the GFS, HWRF, and HMON models keeping Kristy moving northward after 72 h, and the ECMWF and UKMET models moving Kristy westward. The guidance envelope has shifted markedly to the right of the previous forecast track, and the new official forecast track has also been shifted in that direction. However, the new track forecast was not shifted as far east as the consensus models HCCA and FSSE, out of respect for the reliable ECMWF model. There is a narrow window of opportunity of about 24 h for Kristy to strengthen a little more while the cyclone remains over SSTs of 26-26.5 deg C and in a low-shear environment. After that time, however, cooler waters and the entrainment of much drier mid-level air is expected to induce steady weakening through the remainder of the forecast period, with the cyclone becoming post-tropical by 72 h, if not sooner. The official intensity forecast is similar to the intensity consensus model IVCN through 24 h, and then is a little lower than IVCN after that due to Kristy moving over sub-25 deg C SSTs. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 15.8N 130.1W 45 KT 50 MPH 12H 09/1800Z 16.5N 130.2W 45 KT 50 MPH 24H 10/0600Z 17.6N 129.9W 50 KT 60 MPH 36H 10/1800Z 18.7N 129.3W 45 KT 50 MPH 48H 11/0600Z 19.8N 128.9W 45 KT 50 MPH 72H 12/0600Z 21.4N 129.0W 35 KT 40 MPH...POST-TROPICAL 96H 13/0600Z 22.8N 129.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 14/0600Z 23.5N 132.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
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Tropical Storm Debby Forecast Discussion Number 8
2018-08-09 10:37:16| National Hurricane Center (Atlantic)
Issued at 500 AM AST Thu Aug 09 2018 444 WTNT44 KNHC 090837 TCDAT4 Tropical Storm Debby Discussion Number 8 NWS National Hurricane Center Miami FL AL042018 500 AM AST Thu Aug 09 2018 Debby is still hanging on to tropical storm status with a new burst of deep convection having recently developed just south of the low-level center. However, the cyclone's overall cloud pattern has deteriorated significantly since the previous advisory, and there are no longer any convective bands in the region where earlier 40-plus-kt ASCAT winds were observed. As a result, the initial intensity has been lowered slightly to 40 kt, which is consistent with an average of consensus current T-number and current intensity estimates of T2.5 and T3.0, respectively, from both TAFB and SAB. Debby has begun to accelerate northeastward, and the motion estimate is now 055/15 kt. A faster northeastward motion is expected as Debby gets caught up in the high-latitude westerlies ahead of a fast-moving shortwave trough. The small cyclone is forecast to open up into a surface trough by 24 h or so due to Debby moving faster than 20 kt and steady weakening of the circulation over the cold waters of the far north Atlantic. The new NHC track forecast is similar to the previous advisory and basically lies down the middle of the tightly packed guidance envelope. Although Debby has been and is forecast to continue straddling a tight SST gradient with 26+ deg C water just to the southeast and south of the center, the ingestion of drier and more stable air from the north is expected to induce gradual weakening until dissipation or absorption occurs in about 24 h. Debby could briefly become extratropical in about 18 h, followed by dissipation shortly thereafter. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 43.6N 45.1W 40 KT 45 MPH 12H 09/1800Z 45.4N 41.4W 35 KT 40 MPH 24H 10/0600Z...DISSIPATED $$ Forecaster Stewart
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Tropical Storm Debby Forecast Discussion Number 7
2018-08-09 04:41:17| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Wed Aug 08 2018 190 WTNT44 KNHC 090241 TCDAT4 Tropical Storm Debby Discussion Number 7 NWS National Hurricane Center Miami FL AL042018 1100 PM AST Wed Aug 08 2018 A very recent ASCAT pass indicates that Debby is stronger than previously estimated. The pass showed maximum winds of about 40 kt, and since the entire circulation was not captured, the initial intensity is set at 45 kt. This estimate is also in agreement with a Dvorak CI-number from TAFB. Although the relatively compact tropical storm is maintaining an area of moderate convection, the thunderstorm activity is displaced to the south-southwest of the center due to about 15 kt of wind shear. Debby is currently over fairly cool 25 deg C SSTs, but it will be headed for much cooler water during the next 24 to 36 hours. These unfavorable oceanic conditions combined with an increasingly stable airmass should cause weakening and extratropical transition. The NHC intensity forecast shows Debby becoming extratropical by 24 hours and dissipating shortly thereafter, following the GFS and ECMWF models. The tropical storm is moving northeastward, or 040 degrees, at 13 kt. A faster northeastward motion is expected until the cyclone opens into a trough as Debby becomes more embedded in the mid-latitude flow. The NHC track forecast lies near the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 42.8N 46.5W 45 KT 50 MPH 12H 09/1200Z 44.4N 43.7W 40 KT 45 MPH 24H 10/0000Z 46.8N 37.7W 35 KT 40 MPH...POST-TROP/EXTRATROP 36H 10/1200Z...DISSIPATED $$ Forecaster Cangialosi
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Tropical Storm Kristy Forecast Discussion Number 9
2018-08-09 04:40:45| National Hurricane Center (East Pacific)
Issued at 800 PM PDT Wed Aug 08 2018 762 WTPZ43 KNHC 090240 TCDEP3 Tropical Storm Kristy Discussion Number 9 NWS National Hurricane Center Miami FL EP132018 800 PM PDT Wed Aug 08 2018 Deep convection associated with Kristy has increased near and to the east of the center during the past few hours. However, microwave images still show that the convective pattern is not symmetric due to westerly shear associated with a mid- to upper-level low to the north-northeast of the cyclone. The satellite intensity estimates range from 35 to 45 kt, so the initial intensity is again held at 40 kt for this advisory. Kristy will likely have an opportunity to strengthen some during the next day or two while it pulls away from the mid- to upper-level low and remains over relatively warm water. In about 48 hours, however, Kristy is expected to cross the 26 degree C isotherm. These cooler waters along the forecast track and a more stable environment should end the opportunity for strengthening and result in a gradual weakening trend. The intensity models remain quite divergent, with the SHIPS and LGEM models showing little or no strengthening while the HWRF model predicts Kristy to reach hurricane intensity. The NHC intensity forecast lies between these scenarios and is in best agreement with the intensity model consensus. This forecast shows Kristy becoming a post-tropical cyclone by day 4 when the system is expected to be over 23 degree C SSTs. The tropical storm has turned northwestward, with the latest initial motion estimated to be 315/6 kt. A turn to the north is expected on Thursday as Kristy gets drawn toward the larger and stronger Hurricane John. The spread in the models remains really large with the GFS and HWRF models showing Kristy moving northeastward and even merging with John. Conversely, the ECMWF and UKMET models show a northward and then more westward motion when Kristy becomes a weak and shallow system in 4 to 5 days. The NHC track forecast has been adjusted a little to the right, but it remains to the west of the consensus models in favor of the UKMET and ECMWF solutions. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 15.3N 130.0W 40 KT 45 MPH 12H 09/1200Z 16.0N 130.3W 45 KT 50 MPH 24H 10/0000Z 16.9N 130.3W 50 KT 60 MPH 36H 10/1200Z 18.0N 130.1W 50 KT 60 MPH 48H 11/0000Z 19.2N 129.7W 50 KT 60 MPH 72H 12/0000Z 21.0N 129.5W 45 KT 50 MPH 96H 13/0000Z 22.5N 130.0W 35 KT 40 MPH...POST-TROPICAL 120H 14/0000Z 23.0N 131.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Cangialosi
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Hurricane John Forecast Discussion Number 14
2018-08-09 04:32:19| Tropical Depression LIDIA
Issued at 900 PM MDT Wed Aug 08 2018
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