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Tropical Depression FOUR-E Forecast Discussion Number 4
2014-06-29 16:50:56| National Hurricane Center (East Pacific)
Issued at 800 AM PDT SUN JUN 29 2014 000 WTPZ44 KNHC 291450 TCDEP4 TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042014 800 AM PDT SUN JUN 29 2014 Satellite pictures show that the cloud pattern of the cyclone has gradually been increasing in organization this morning. A large band consisting of very cold-topped convection covers the western semicircle of the circulation, and deep convection has also begun to develop around the center in what appears to be the beginnings of an inner core. Subjective Dvorak intensity estimates remain at 2.0 from both TAFB and SAB, so the initial intensity estimate is kept at 30 kt for this advisory. However, recent trends suggest that the depression is very near tropical-storm strength. The center position has been difficult to determine, which, in turn, makes the depression's initial motion rather uncertain. A smoothing of the latest fixes suggests that the cyclone continues to move quickly toward the west-northwest, or 295/14, due to a strong subtropical ridge located to the north of the cyclone. Global models show a weak mid- to upper-level trough extending southward offshore of the California coast during the next few days, which is forecast to cause this ridge to weaken. This change in the steering pattern should result in a substantial reduction in the cyclone's forward speed with the track bending toward the west once the circulation becomes more shallow in nature. The NHC forecast track is quite a bit faster and to the right of the previous one, primarily due to the re-location of the center based upon first-light visible images. The forecast track lies on the far left side of the guidance envelope, closest to the ECMWF solution. Environmental conditions are favorable for strengthening during the next couple of days, but the large size and slow evolution of the inner core of the depression suggests that only gradual intensification is likely to occur. Beyond that time, the cyclone should reach cooler waters and move into a somewhat drier and more stable air mass, which should bring a halt to any further strengthening. The large-scale conditions should not, however, be hostile enough to cause a rapid decay of the cyclone, so only slow weakening is indicated late in the forecast period. The NHC intensity forecast is similar to the previous one, and is close to the multi-model consensus through 72 hours, but is a little lower on days 4-5. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 16.4N 110.3W 30 KT 35 MPH 12H 30/0000Z 17.0N 112.4W 40 KT 45 MPH 24H 30/1200Z 17.5N 114.1W 50 KT 60 MPH 36H 01/0000Z 18.1N 115.4W 55 KT 65 MPH 48H 01/1200Z 18.5N 116.5W 55 KT 65 MPH 72H 02/1200Z 18.7N 117.7W 50 KT 60 MPH 96H 03/1200Z 18.7N 118.7W 35 KT 40 MPH 120H 04/1200Z 18.7N 120.0W 30 KT 35 MPH $$ Forecaster Kimberlain
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