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Tropical Storm NICOLE Forecast Discussion Number 14
2016-10-07 16:36:34| National Hurricane Center (Atlantic)
Issued at 1100 AM AST FRI OCT 07 2016 000 WTNT45 KNHC 071436 TCDAT5 TROPICAL STORM NICOLE DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152016 1100 AM AST FRI OCT 07 2016 Strong shear has taken its toll on Nicole overnight. The cyclone's cloud pattern has rapidly deteriorated, with the low-level center now exposed to the northwest of a greatly reduced area of deep convection. Dvorak Final T-numbers have decreased quickly to T3.5 from SAB and TAFB, and a blend of these and CI-numbers was used to set the initial intensity to 65 kt at 1200 UTC. Since the cloud pattern has degraded even further since that time, the advisory intensity is lowered to 60 kt, which could prove to be generous. Nicole has barely been moving, and the initial motion estimate is nearly stationary. Although Nicole remains in a region of weak steering at the moment, a blocking mid-level high should build north of the cyclone soon, and impart a slow motion generally toward the south for the next couple of days. Around 48 hours, a mid-level ridge is forecast to develop to the east of Nicole, which should result in the cyclone gradually turning northward with some increase in forward speed through the remainder of the forecast period. Most of the model guidance is in better agreement than yesterday on this scenario, which increases the overall confidence of the track forecast. The new track forecast is based on a consensus of the regional and global models minus the GFDL. A potent mid- to upper-level shortwave trough digging to the east of Nicole should cause deep-layer northerly shear over the cyclone to increase further today. In the wake of the shortwave, the shear should veer to the north-northeast but remain just as strong through about 72 hours. Nicole is also shown interacting with a lobe of vorticity that fractures from the shortwave, but it remains unclear how this interaction would affect the cyclone's intensity or structure. Regardless, the overall hostile environment should cause weakening, perhaps even more than indicated in this forecast. Indications are that late in the forecast period the large- scale environment should become more conducive for Nicole to re-intensify, but to what extent is in doubt. As a result of developments overnight, the new intensity forecast is substantially lower than the previous one and is below all of the intensity guidance through 72 hours. It is near the multi-model consensus after that time, although this part of the forecast is of low confidence. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 27.5N 65.3W 60 KT 70 MPH 12H 08/0000Z 27.0N 65.1W 50 KT 60 MPH 24H 08/1200Z 26.1N 64.8W 45 KT 50 MPH 36H 09/0000Z 25.4N 64.7W 40 KT 45 MPH 48H 09/1200Z 25.3N 65.1W 40 KT 45 MPH 72H 10/1200Z 26.6N 65.7W 35 KT 40 MPH 96H 11/1200Z 28.8N 66.1W 40 KT 45 MPH 120H 12/1200Z 32.0N 65.6W 50 KT 60 MPH $$ Forecaster Kimberlain
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