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#707812 (Received by flhurricane at: 10:35 AM 05.Aug.2014) TCDAT3 TROPICAL STORM BERTHA DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL032014 1100 AM EDT TUE AUG 05 2014 Increasing westerly vertical shear is displacing deep convection to the east of the low-level center of Bertha, which is clearly exposed in visible satellite images. The current intensity is adjusted down a bit in accordance with observations from a NOAA Hurricane Hunter plane a few hours ago. Since the shear is forecast to become even stronger over the next couple of days, additional weakening would be expected due to those conditions. However, the cyclone might be able to draw energy from baroclinic process associated with a frontal zone not far to its north, and maintain at least some of its intensity. The system is forecast to merge with that front and become an extratropical cyclone within 36 hours. It is also possible, however, that the shear will become so strong that Bertha would be reduced to a convection-free post-tropical cyclone before extratropical transition takes place. The NOAA Ocean Prediction Center has provided input to the official intensity forecast. Bertha continues moving north-northeastward near 19 kt. The tropical, or post-tropical, cyclone is forecast to accelerate northeastward ahead of an amplifying mid-level trough near the United States east coast during the next couple of days. Thereafter, the system should move quickly east-northeastward to eastward in the mid-latitude westerlies over the North Atlantic. The track forecast for 36 hours and beyond is also based on input from the Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 34.8N 71.9W 50 KT 60 MPH 12H 06/0000Z 37.1N 69.2W 50 KT 60 MPH 24H 06/1200Z 39.8N 64.5W 50 KT 60 MPH 36H 07/0000Z 42.5N 59.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 07/1200Z 45.0N 53.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 08/1200Z 49.0N 40.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 09/1200Z 49.0N 22.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 10/1200Z 51.0N 2.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch |