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Hurricane NICOLE Forecast Discussion Number 51
2016-10-16 22:45:36| National Hurricane Center (Atlantic)
Issued at 500 PM AST SUN OCT 16 2016 000 WTNT45 KNHC 162045 TCDAT5 HURRICANE NICOLE DISCUSSION NUMBER 51 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152016 500 PM AST SUN OCT 16 2016 Nicole's 70 nmi wide ragged eye remains distinct, surrounded by a nearly closed ring of convection consisting of cloud tops of -45C to -55C. However, the overall cloud pattern is beginning to look more like an extratropical low pressure system than that of a tropical cyclone. The initial intensity has been lowered to 70 kt, which is closer to the latest subjective and objective Dvorak intensity estimate of T4.0/65 kt from both TAFB and NHC. Nicole appears to have finally made the much anticipated turn to the northeast, and is now moving 045/08 kt. Nicole currently is trapped between two high-amplitude ridges -- one located offshore of eastern Canada and the other to the west of Europe. The latest 12Z model guidance remains in excellent agreement on this blocking ridge pattern breaking down over the next few days as a strong shortwave trough currently located over northeastern Canada moves quickly eastward. The increasing southwesterly deep-layer flow ahead of the trough should begin to accelerate Nicole northeastward tonight and Monday, and then turn the cyclone north-northeastward over the far North Atlantic on Tuesday. The track models are in very good agreement on this developing track scenario, so the new NHC forecast track is essentially just an extension of the previous advisory track, and lies close to a blend of the various consensus models and input from the NOAA Ocean Prediction Center (OPC) at 48-72h. Although Nicole is currently located over marginal sea surface temperatures of about 24 deg C, it is beneath a region of unusually cold upper-tropospheric temperatures, creating an unstable condition barely sufficient to support convection in the inner-core region of the cyclone. However, the latest SHIPS intensity guidance indicates that SSTs will be cooling to 22C and less by 24 h, after which the atmosphere is forecast to become too stable to produce convection. As a result, Nicole is expected to become an extratropical low by 36 hours. However, the intensity forecast shows only slight weakening during the next 48 h due to the system receiving a shot of baroclinic energy from the aforementioned shortwave trough. By 96 h, if not sooner, Nicole is expected to be absorbed by a larger extratropical low near the east coast of Greenland. Guidance from the NOAA OPC was used for the forecast wind radii at 48 h and 72 h. The primary hazard associated with Nicole will be high seas. Recent wave-height altimeter data indicate that a large area of 20-ft seas exist near the hurricane. In addition, swells from Nicole are spreading far from the system, and High Seas Forecasts from OPC and TAFB indicate that long-period swells will continue to radiate outward and affect much of the North Atlantic basin during the next few days. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 39.7N 45.6W 70 KT 80 MPH 12H 17/0600Z 40.5N 44.5W 65 KT 75 MPH 24H 17/1800Z 42.6N 42.5W 65 KT 75 MPH 36H 18/0600Z 46.3N 39.6W 65 KT 75 MPH...POST-TROP/EXTRATROP 48H 18/1800Z 51.3N 37.3W 65 KT 75 MPH...POST-TROP/EXTRATROP 72H 19/1800Z 59.6N 32.7W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 20/1800Z...ABSORBED BY LARGER EXTRATROPICAL LOW $$ Forecaster Stewart
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