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Tropical Storm BERTHA Forecast Discussion Number 2
2014-08-01 10:48:09| National Hurricane Center (Atlantic)
Issued at 500 AM AST FRI AUG 01 2014 000 WTNT43 KNHC 010847 TCDAT3 TROPICAL STORM BERTHA DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL032014 500 AM AST FRI AUG 01 2014 Bertha is a sheared tropical cyclone with the center located on the western edge of the deep convection as indicated by satellite. The low-level circulation continues to be vigorous, but given the current westerly shear the outflow is very limited. There are no reasons to change the initial intensity which is kept at 40 knots. Another Air Force reconnaissance plane will investigate Bertha in the next several hours. The current shear environment is not particularly favorable for strengthening, but there are some indications by the global models that the shear could decrease some as Bertha moves across the northeastern Caribbean Sea. This should allow some slight intensification during the next 24 to 36 hours. Once Bertha's circulation moves away from Hispaniola beyond 48 hours, there is an opportunity for additional strengthening if the shear becomes lighter as suggested by global and statistical models. At this time, the NHC forecast keeps Bertha with 45-knot winds over the western Atlantic until it becomes more certain that the shear could subside. Bertha continues racing toward the west-northwest or 290 degrees at 17 knots. The cyclone is being steered by the flow around the Atlantic subtropical ridge which is forecast to persist. Once in the western Atlantic near the eastern Bahamas, Bertha will be steered by the southerly flow between the subtropical high and a mid-level trough over the eastern United States. This pattern will force Bertha to turn northward with a decrease in forward speed and to eventually recurve northeastward over the Atlantic. The confidence in the track forecast, primarily in the next 2 to 3 days, is high since most the guidance is tightly clustered. The confidence decreases after 3 days when the guidance becomes divergent. The track envelope, however, brings Bertha northward and then northeastward over the Atlantic, and the NHC forecast follows closely the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 13.0N 57.0W 40 KT 45 MPH 12H 01/1800Z 14.0N 59.6W 40 KT 45 MPH 24H 02/0600Z 15.5N 63.0W 40 KT 45 MPH 36H 02/1800Z 17.2N 66.0W 45 KT 50 MPH 48H 03/0600Z 19.5N 68.8W 45 KT 50 MPH 72H 04/0600Z 24.5N 73.5W 45 KT 50 MPH 96H 05/0600Z 29.0N 74.0W 45 KT 50 MPH 120H 06/0600Z 35.0N 67.5W 45 KT 50 MPH $$ Forecaster Avila
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