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Tropical Storm Chris Forecast Discussion Number 11
2018-07-09 10:43:15| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Mon Jul 09 2018 000 WTNT43 KNHC 090843 TCDAT3 Tropical Storm Chris Discussion Number 11 NWS National Hurricane Center Miami FL AL032018 500 AM EDT Mon Jul 09 2018 After the expansion of deep convection during the evening it appears that some drier air has been entrained into the circulation which has caused a general warming of the cloud tops and some erosion of the deep convection overnight. However, the banding remains well organized and the overall structure of the cyclone has not changed appreciably. An Air Force Reserve reconnaissance aircraft investigating the system has found that the minimum pressure has dropped to 999 mb, but the flight-level and SFMR winds still support an initial intensity of 50 kt. Recent aircraft and satellite fixes indicate that Chris is drifting southward. Steering currents are expected to remain quite weak during the next 36 hours as Chris is situated between a couple of mid-level highs and a mid- to upper-level trough to its northeast. By late Tuesday, a deep-layer trough moving across the Great Lakes region should begin to lift Chris out toward the northeast. The cyclone is predicted to accelerate northeastward during the remainder of the forecast period as it gets caught in strong southwesterly flow ahead of the aforementioned trough. The track models are in good agreement on this general scenario but there are some differences in how fast Chris accelerates over the western Atlantic. The new NHC track forecast has been shifted slightly northwestward to be in better agreement with the latest guidance, and it remains near the model consensus to account for the forward speed differences among the various track models. The cyclone should be able to mix out the dry air that it entrained while it is located over warm water and in light to moderate vertical wind shear conditions. This should allow strengthening during the next couple of days, but there could be some upwelling beneath the slow moving cyclone which could temper the rate of intensification. The new NHC track forecast shows a slightly slower rate of deepening during the next 24 to 36 h, but still forecasts Chris to become a hurricane later today or tonight, and reach about the same peak intensity as shown in the previous advisory. The hurricane should become extratropical by 96 h, and the global models indicate that steady weakening will occur after that time. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 32.4N 74.6W 50 KT 60 MPH 12H 09/1800Z 32.4N 74.6W 55 KT 65 MPH 24H 10/0600Z 32.5N 74.7W 65 KT 75 MPH 36H 10/1800Z 33.0N 73.9W 70 KT 80 MPH 48H 11/0600Z 34.2N 72.2W 80 KT 90 MPH 72H 12/0600Z 39.0N 66.4W 80 KT 90 MPH 96H 13/0600Z 45.5N 59.3W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 14/0600Z 49.5N 49.5W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown
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