ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 1100 PM AST SAT AUG 23 2014 Satellite imagery indicates that Tropical Depression Four has changed little in organization during the past several hours. While the convection remains somewhat ragged, a persistent area of stronger convection has formed near the center. Data from NOAA and Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds are near 30 kt, which is in agreement with the satellite intensity estimate from TAFB. The cirrus outflow is good over the eastern semicircle and poor elsewhere. The initial motion is a somewhat uncertain 320/8. The cyclone should continue moving northwestward and north-northwestward into a developing break in the subtropical ridge cause by a mid- to upper- level trough off of the U.S. east coast. As the trough begins to lift out and steering currents weaken, a slow motion is expected in 36 to 48 hours. The track guidance becomes very divergent at that time. The UKMET and the NAVGEM models build enough ridging north of the cyclone to steer it across Florida and into the Gulf of Mexico. The Canadian model currently forecasts a quick right turn with the cyclone moving well out to sea. The ECMWF and the GFS keep a stronger ridge east of the cyclone and thus forecast a more northward motion east of the southeastern United States, followed by a northeastward turn. However, the GFS does show a westward wobble just north of the Bahamas before the turn. The new forecast track is nudged a little to the east of the previous track, and it lies a little to the left of the TVCA consensus and the center of the guidance envelope. As mentioned in the previous discussion, the confidence in the track forecast is lower than normal. The large-scale models suggest that the cyclone should experience light to moderate westerly or northwesterly vertical wind shear throughout the forecast period. The intensity guidance forecasts less strengthening than earlier, which necessitates some downward adjustment of the new intensity forecast. Even with this change, the new forecast is on the upper edge of the intensity guidance. Overall, the forecast is close to the IVCN intensity consensus. FORECAST POSITIONS AND MAX WINDS INIT 24/0300Z 22.3N 72.6W 30 KT 35 MPH 12H 24/1200Z 23.1N 73.4W 35 KT 40 MPH 24H 25/0000Z 23.9N 74.0W 40 KT 45 MPH 36H 25/1200Z 24.4N 74.3W 45 KT 50 MPH 48H 26/0000Z 24.8N 74.6W 50 KT 60 MPH 72H 27/0000Z 27.0N 76.0W 60 KT 70 MPH 96H 28/0000Z 29.5N 77.0W 65 KT 75 MPH 120H 29/0000Z 32.5N 75.0W 70 KT 80 MPH $$ Forecaster Beven NNNN