je.st
news
Tropical Storm FIONA Forecast Discussion Number 10
2016-08-19 10:46:59| National Hurricane Center (Atlantic)
Issued at 500 AM AST FRI AUG 19 2016 000 WTNT41 KNHC 190846 TCDAT1 TROPICAL STORM FIONA DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016 500 AM AST FRI AUG 19 2016 Fiona hasn't really changed much overall in the past several hours with an earlier burst of convection having dissipated and a new burst taking its place. Microwave data suggest the center is near or south of the main area of thunderstorms, which is a sign of the ongoing southwesterly shear. The initial wind speed is kept at 40 kt for this advisory since the Dvorak estimates are the same as the previous cycle. Little significant change is expected with Fiona's intensity today due to gradually increasing shear. The storm should weaken over the weekend as the shear further increases, along with the likely entrainment of drier mid-level air. While the environmental conditions might get less hostile at the end of the period, it is uncertain how much will be left of Fiona at that time to take advantage of that change, with some suggestion in the global models that Fiona could decay to a remnant low by then. Thus, the new NHC intensity forecast is a bit lower than the previous one, near a model consensus than excludes the GFDL (which has looked consistently too high). A timely AMSR2 pass helped show that Fiona has sped up, and is now moving 300/9. Fiona should move around the Atlantic subtropical ridge for the next few days. The biggest change to the track guidance is that all of the models have shifted a few degrees westward at long range. This appears to be due to less of a trough forecast over the central Atlantic and a weaker representation of Fiona in the global models, both of which would cause the storm to continue moving northwestward for a longer period of time. The new NHC track forecast follows the trend of the models, but remains a fair distance east of the model consensus at days 4 and 5 due to continuity constraints. It would not be surprising if further westward adjustments had to be made later today. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 17.6N 42.7W 40 KT 45 MPH 12H 19/1800Z 18.2N 44.0W 40 KT 45 MPH 24H 20/0600Z 19.1N 46.0W 35 KT 40 MPH 36H 20/1800Z 20.2N 48.1W 35 KT 40 MPH 48H 21/0600Z 21.3N 50.3W 30 KT 35 MPH 72H 22/0600Z 23.5N 54.8W 30 KT 35 MPH 96H 23/0600Z 26.0N 57.5W 30 KT 35 MPH 120H 24/0600Z 28.0N 59.0W 30 KT 35 MPH $$ Forecaster Blake
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics