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Tropical Storm CRISTOBAL Forecast Discussion Number 6
2014-08-25 04:33:32| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT SUN AUG 24 2014 000 WTNT44 KNHC 250233 TCDAT4 TROPICAL STORM CRISTOBAL DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 1100 PM EDT SUN AUG 24 2014 Cristobal is not a well-organized tropical cyclone at this time. The deep convection has a ragged appearance, with little or no banding features evident, and this convection is mainly occurring well to the south of the estimated center location. After adjusting for rain inflation, SFMR winds from aircraft observations a few hours ago, indicated that the intensity is no more than 40 kt. Also, the fixes from the Air Force and NOAA planes, which were flying at altitudes of about 1000 and 8000 feet respectively, indicated a southward tilt of the center with height. This is consistent with some northerly shear over the storm as suggested by water vapor imagery. Given the currently disorganized state of Cristobal, not much intensification seems likely for the next 12 hours or so. Afterwards, the global models are predicting a little more favorable upper-tropospheric environment with increasingly diffluent flow over the tropical cyclone. The official intensity forecast is basically a blend of the SHIPS and LGEM guidance, and only a little above the model consensus. By 120 hours, the global models depict the cyclone embedded within a baroclinic zone, so extratropical transition should have occurred by that time. The motion has been rather erratic over the past several hours, but my best estimate is about 350/4 kt. Cristobal is currently situated near a col between 2 anticyclones in the mid-level flow, one over the United States, and one over the central subtropical Atlantic. The dynamical models indicate that, within a couple of days, the steering of the tropical cyclone will become dominated by flow on the northwest side of the Atlantic anticyclone and on the southern side of a mid-latitude trough. Therefore, the motion is expected to gradually bend to the right with some acceleration over the next several days. The official track forecast is somewhat faster than the previous one after 48 hours, but not as fast as the latest dynamical model consensus. FORECAST POSITIONS AND MAX WINDS INIT 25/0300Z 24.8N 73.1W 40 KT 45 MPH 12H 25/1200Z 25.4N 73.1W 40 KT 45 MPH 24H 26/0000Z 26.4N 72.8W 45 KT 50 MPH 36H 26/1200Z 27.8N 72.4W 50 KT 60 MPH 48H 27/0000Z 29.8N 71.8W 55 KT 65 MPH 72H 28/0000Z 33.5N 69.0W 65 KT 75 MPH 96H 29/0000Z 37.5N 62.0W 70 KT 80 MPH 120H 30/0000Z 44.0N 50.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch
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