(ABOVE IMAGE) A National Weather Service image shows the latest 5 day track for Tropical Storm Ana.
- Tropical Storm Ana is 680 miles southeast of Hilo, Hawaii. Ana is moving toward the west near 9 mph, and the National Weather Service says, “this general motion is expected to continue today, with a gradual turn toward the west northwest expected tonight or early Thursday, and this motion is expected to continue through late Thursday.”
- Maximum sustained winds are near 70 mph with higher gusts. Ana is forecast to gradually intensify through Thursday night, and it may become a hurricane later today or tonight. Tropical storm force winds extend outward up to 65 miles, 100 km from the center.
Ana remains a strong tropical storm early this morning. An ascat scatterometer pass at 0644z over the center of ana plus multiple passes from microwave imagery available on the fnmoc/nrl web sites indicated that the llcc of Ana was along the northeastern edge of the persistent cold central dense overcast… Which has been over the system for almost 36 hours now. As a result… We have nudged the initial track northward… Which is often the case when we are tracking cloud system centers… Especially with infrared satellite imagery. The location of the llcc is also indicative of the vertical wind shear… Which has been from the northeast or east northeast at 5 to 10 kt since late Wednesday. The most recent subjective dvorak intensity estimates for Ana are 3.5/55 kt from phfo and jtwc… While the sab estimate is 4.0/65 kt. The initial intensity for this advisory will remain 60 kt. Note that the ascat pass was used to refine the initial wind radii for this advisory.
Strong tropical storm ana is currently moving toward the west…Or 275 degrees… At 8 kt. Ana continues to be steered along this course by a deep layer ridge which developed to its north starting
Tuesday. The current track forecast has been nudged slightly to the left toward the most recent tvcn track consensus guidance. The hwfi and gfdi are to the right of the tvcn… While most of the global models are to the left of the tvcn. The guidance remains rather tightly clustered through the next 36 to 48 hours… Followed by a wider spread beyond that time. This is likely due to the ridge shifting toward the southeast by Friday… Which will begin to steer ana more toward the northwest this weekend. Despite the fact there is still significant vertical wind shear of 40 to 50 kt between Ana and the main Hawaiian Islands… The forecast models do not currently show that Ana will be impacted by these hostile environmental conditions along the forecast track. Instead…Ana is expected to remain in minimal wind shear conditions south of the ridge for at least the next 48 hours. Starting Friday…All of the forecast models appear to show a mid-latitude upper level trough passing by to the north of Ana will weaken the steering currents. Each model has a slightly different solution about the strength and location of this upper level trough. As a result… There is still a great deal of uncertainty about the impact this upper level feature will have on Ana. One final note… The NOAA g-iv aircraft is scheduled to sample the environment surrounding Ana… Which will help to better define the steering currents for the forecast models.
The intensity forecast is close to the previous one… With Ana potentially becoming a hurricane later today or tonight due to the relatively light vertical wind shear and warm ssts along the forecast track. The intensity forecast remains close to the icon consensus guidance. In addition… The latest cira ocean heat content analyses along the projected track show the value will ramp up during the 48 to 72 hour period… So there should be plenty of ocean warmth available to the system while its surface winds are very strong. The peak intensity is expected Thursday and Friday. A gradual weakening trend is forecast this weekend as the previously mentioned vertical wind shear values start to increase in the forecast guidance. Also… There may be some interruption of the low-level circulation if it interacts with any of the main Hawaiian Islands… Especially the Big Island.
Interests in the main Hawaiian Islands should continue to monitor the future progress of Ana. A hurricane watch may be required for portions of the island chain later today or tonight.National Weather Service on Oct. 15 at 5 a.m. HST.