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Tropical Storm FAY Forecast Discussion Number 13
2014-10-13 10:48:37| National Hurricane Center (Atlantic)
Issued at 500 AM AST MON OCT 13 2014 000 WTNT42 KNHC 130848 TCDAT2 TROPICAL STORM FAY DISCUSSION NUMBER 13 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072014 500 AM AST MON OCT 13 2014 A series of microwave images indicate that Fay has begun extratropical transition. The cloud pattern has become quite asymmetric and the remaining central deep convection, situated well to the northeast of the center of circulation, is decreasing. An earlier AMSU-B overpass showed significant erosion of the southern flank of Fay due to intruding cold, dry, low to mid-level air associated with an approaching strong baroclinic frontal zone. Furthermore, the GFS model-forecast cyclone phase diagram shows Fay completing transition to an asymmetric cold core system in 12 hours or so. A compromise of the objective and subjective satellite intensity estimates keeps the initial intensity at 55 kt for this advisory. Although the cyclone is expected to remain generally in warm water south of the Gulf Stream's north wall, strong, persistent, vertical shear is forecast to further weaken Fay through the 72 hr period. Afterward, the post-tropical cyclone should continue to decay and open up into a trough of low pressure within the aforementioned frontal boundary and dissipate over the northeastern Atlantic. Based on a consensus of the global models, an adjustment to the length of the official forecast has been made, and it now postpones dissipation until day 4. The tropical storm is gradually accelerating eastward and is now moving at 23 kt within the mid-latitude westerlies. Fay is forecast to slow a bit during the next 24 hours, in response to interaction with the cold front, and track eastward to east-southeastward until dissipation. The NHC forecast is close to the TVCA multi-model consensus and the post-tropical cyclone forecast guidance from the Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 34.3N 55.3W 55 KT 65 MPH 12H 13/1800Z 34.3N 51.2W 50 KT 60 MPH...POST-TROP/EXTRATROP 24H 14/0600Z 33.7N 47.2W 40 KT 45 MPH...POST-TROP/EXTRATROP 36H 14/1800Z 32.7N 43.2W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 15/0600Z 32.1N 39.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 72H 16/0600Z 32.0N 32.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 17/0600Z...DISSIPATED $$ Forecaster Roberts
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