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Tropical Storm NICOLE Forecast Discussion Number 23
2016-10-09 22:40:49| National Hurricane Center (Atlantic)
Issued at 500 PM AST SUN OCT 09 2016 000 WTNT45 KNHC 092040 TCDAT5 TROPICAL STORM NICOLE DISCUSSION NUMBER 23 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152016 500 PM AST SUN OCT 09 2016 Nicole's cloud pattern has become better organized this afternoon. Deep convection has been pulsing but, unlike yesterday, it has not diminished. The cyclone's maintenance of deep convection suggests that the vertical shear has decreased, which is supported by the SHIPS analyses. In addition, the low-level center is underneath but on the northwestern side of a formative and expanding central dense overcast, consisting of cold cloud tops. Dvorak classifications are T3.5 from TAFB and SAB, and the initial intensity estimate is therefore raised to 55 kt. Nicole has been nearly stationary during the last several hours. A slow motion generally toward the north or north-northwest is expected to commence soon, now that the blocking high north of it has slid to the northeast of Nicole. A shortwave trough currently over the northeastern United States is shown in global model solutions bypassing Nicole in about 2 days. The ECMWF has stronger ridging in the wake of this feature than the GFS, and thus carries Nicole farther to the west as did the 0000 UTC ECMWF ensembles. A turn toward the north and northeast is likely after 72 hours once Nicole reaches a belt of stronger mid-latitude southwesterly flow. The new track forecast is adjusted slightly to the left of the previous one and is slower, and it is shifted again toward the ECMWF. The NHC track is close to an average of the ECMWF and GFS models and to the west of the other model consensus aids. Northerly vertical shear of 20 to 25 kt over Nicole will continue for about another 24 hours, which should prevent significant intensification from occurring. After that time, the shear is forecast to gradually diminish and remain relatively low until about 3 days. The reduction of shear, in combination with near-record warm SSTs, a relatively moist environment, and an increasingly diffluent flow aloft, suggest that intensification is likely. The only caveat involves much a cooler and drier air mass in the wake of Post-Tropical Cyclone Matthew would affect Nicole. The new intensity forecast is increased again, much more than in the previous advisory, and is near the high end of the guidance in closest agreement with the SHIPS model. It is worth mentioning that global models continue to show significant deepening in 2 to 3 days, still more than indicated in the current forecast. The guidance shows a sharp increase in shear by 96 hours, which ordinarily would curb any further intensification. However, baroclinic forcing could offset the negative effects of the shear and Nicole should at a minimum maintain its intensity if not intensify a bit further. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 24.2N 65.3W 55 KT 65 MPH 12H 10/0600Z 25.0N 65.2W 60 KT 70 MPH 24H 10/1800Z 25.9N 65.3W 65 KT 75 MPH 36H 11/0600Z 26.6N 65.5W 70 KT 80 MPH 48H 11/1800Z 27.2N 65.9W 75 KT 85 MPH 72H 12/1800Z 28.4N 66.4W 80 KT 90 MPH 96H 13/1800Z 31.3N 65.0W 80 KT 90 MPH 120H 14/1800Z 35.4N 59.0W 75 KT 85 MPH $$ Forecaster Kimberlain
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