Show Selection: |
#712561 (Received by flhurricane at: 4:57 AM 24.Aug.2014) TCDAT4 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 500 AM AST SUN AUG 24 2014 The satellite presentation of the tropical depression has gradually improved overnight. Convection has increased to the northeast of the center and a little more banding is noted. Although the pressure has dropped a few millibars during the past 6 to 12 hours, data from an Air Force Reserve Hurricane Hunter aircraft indicate that the cyclone remains a 30-kt tropical depression. Fixes from the aircraft yield an initial motion of 325/8 kt. The cyclone is expected to slow down and turn north-northwestward today into a break in the ridge caused by a mid- to upper-level trough that is currently moving off the U.S. east coast. This trough is forecast to dig southeastward during the next 24 to 36 hours before lifting northeastward on Tuesday. The track guidance has shifted significantly eastward this cycle, with the exception of the latest ECMWF, which is very similar to its 1200 UTC run. The eastward shift in most of the models appears to be the result of increased interaction of the cyclone with the aforementioned trough during the next 48 hours. This leads to a more north-northwestward or northward motion during the next day or so. Once the trough lifts out, most of the guidance shows a bend back toward the northwest, before the cyclone turns northward and northeast around a subtropical ridge to its east. The NHC track has been shifted eastward, but it remains along the western side of the guidance envelope out of respect for the ECMWF and continuity of the previous forecasts. The new track forecast is closest to the HWRF, but is well west of the latest multi-model consensus. Future eastward adjustments may be required if the eastward model trend continues. Given that a large spread remains in the guidance, the confidence in the track forecast remains lower than normal. Light to moderate northwesterly shear is expected during the next few days. However, the shear is not expected to be strong enough to prevent strengthening, and the official forecast calls for gradual intensification throughout the forecast period. The NHC intensity forecast is close to the SHIPS guidance and the intensity consensus ICON. FORECAST POSITIONS AND MAX WINDS INIT 24/0900Z 22.9N 73.3W 30 KT 35 MPH 12H 24/1800Z 23.7N 73.7W 40 KT 45 MPH 24H 25/0600Z 24.4N 73.9W 45 KT 50 MPH 36H 25/1800Z 25.0N 74.0W 50 KT 60 MPH 48H 26/0600Z 25.9N 74.1W 55 KT 65 MPH 72H 27/0600Z 28.5N 75.5W 60 KT 70 MPH 96H 28/0600Z 31.5N 75.0W 65 KT 75 MPH 120H 29/0600Z 34.0N 70.0W 70 KT 80 MPH $$ Forecaster Brown |