8/29/19 8AM Hurricane Dorian Update

Author: || Published: 8/29/2019 at 7:25am
8/29/19 five-day forecast fromt eh NHC // Courtesy: nhc.noaa.gov

Hurricane Dorian ate some dry air overnight and that limited the amount of intensification. As the storm continues to drift NW it will eventually find an area of reduced shear and higher humidity and intensification will continue.

Current stats:

SUMMARY OF 500 AM AST…0900 UTC…INFORMATION
———————————————-
LOCATION…20.5N 66.6W
ABOUT 150 MI…240 KM NNW OF SAN JUAN PUERTO RICO
ABOUT 425 MI…685 KM ESE OF THE SOUTHEASTERN BAHAMAS
MAXIMUM SUSTAINED WINDS…85 MPH…140 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 13 MPH…20 KM/H
MINIMUM CENTRAL PRESSURE…991 MB…29.27 INCHES



From the NHC

At 500 AM AST (0900 UTC), the center of Hurricane Dorian was located near latitude 20.5 North, longitude 66.6 West. Dorian is moving
toward the northwest near 13 mph (20 km/h), and this general motion is expected to continue through Friday. A west-northwestward motion is forecast to begin Friday night and continue into the weekend. On this track, Dorian should move over the Atlantic well east of the southeastern and central Bahamas today and on Friday, and approach the northwestern Bahamas on Saturday.

8/29/19 five day wind-speed probability forecast from the NHC // Courtesy: nhc.noaa.gov

Maximum sustained winds are near 85 mph (140 km/h) with higher gusts. Strengthening is forecast during the next few days, and Dorian is expected to become a major hurricane on Friday.

Hurricane-force winds extend outward up to 15 miles (30 km) from the center, and tropical-storm-force winds extend outward up to 90 miles (150 km).

The minimum central pressure based on earlier Air Force Reserve Hurricane Hunter data is 991 mb (29.27 inches).

Extra NHC Discussion

Hurricane Dorian Discussion Number 20
NWS National Hurricane Center Miami FL AL052019
500 AM AST Thu Aug 29 2019

Soon after the previous advisory was issued, Dorian appeared to have a bit of a hiccup in its structure. A dry slot was noted penetrating into the southeastern portion of the circulation, with the eye becoming cloud- and rain-filled. In fact, dropsonde data from the Air Force Reserve mission indicated that the central pressure had come back up a bit to around 991 mb. That being said, the plane still measured maximum SFMR winds between 70-75 kt, so the initial intensity is being held steady at 75 kt for this advisory.

Dorian continues northwestward, or 325 degrees at 11 kt. Confidence in the track forecast is fairly high for the first 48 hours, with Dorian expected to continue moving northwestward and then begin to turn west-northwestward between mid-level ridging to the north and a mid- to upper-level low retrograding westward across the Straits of Florida. The models, and their ensembles, continue to diverge after 48 hours and have not really budged from their respective solutions compared to yesterday. The GFS is a northern outlier from the rest of the guidance, showing a weaker ridge and bringing Dorian close to the Florida/Georgia border, while the UKMET and ECMWF models show stronger ridges and remain the southernmost solutions near South Florida. Given the spread in the guidance, the new NHC forecast blends the previous forecast with the simple multi-model consensus aids and the HCCA and Florida State Superensemble aids, and it actually ends up in a position very close to the tightly clustered global model ensemble means. The most notable change in the new forecast is that it’s a little bit slower than the previous one as Dorian approaches Florida.

Various shear analyses are indicating 10-15 kt of southwesterly shear over Dorian at the moment, but the global models show this shear diminishing within 12-24 hours. With lower shear and very warm waters, all of the intensity models forecast Dorian to begin strengthening again soon, and rapid intensification could occur. The updated NHC intensity forecast has been increased from the previous one and most closely follows the HCCA and Florida State Superensemble aids during the first day or two. After 48 hours, the official forecast is near or just above the intensity consensus, but it’s still lower than the solutions shown by the HCCA, Florida State Superensemble, and the HWRF. Dorian is likely to reach major hurricane strength in the next day or two and is forecast to maintain that status until it reaches land.




What other meteorologists are saying about the model data

There are a lot of great follows on Twitter full of good information about this storm.

But the best follow on Twitter about this storm will always be the NHC.

Will it get into the Gulf?

We don’t know this yet, sadly. I am still hoping that by this afternoon we will have a much better idea. But the fight between the two ridges of high pressure will be the deciding factor.

I touched on that here: 8/28/19 Tropical Update

And also here: 8/28/19 Dorian data breakdown

The parts of the forecast that are a total lock

No parts. This forecast is likely to change. Sadly, with tropical systems nothing is ever truly ‘locked in’ which is why we always encourage you to follow the forecast with these systems closely. It is also why we try our best to kick out new forecasts as much as possible.

The Bottom Line

Right now – unless you are reading this from the Caribbean – we are in a wait-and-see position. Circling the airport, so to speak. For Gulf Coast folks, as I mentioned last night on the 10p news, we may have to wait until Thursday evening before we get a better idea about what it means for the Louisiana, Mississippi and Alabama region.

So for now, check your Hurricane Preparedness Kit, check your supplies, make sure you have a plan. Double-check your insurance coverage, make sure you don’t have trees with loose branches or dead limbs around or near the house, and check nearby storm drains. But outside of that, just hang tight!




Author of the article:


Nick Lilja

Nick is former television meteorologist with stints in Amarillo and Hattiesburg. During his time in Hattiesburg, he was also an adjunct professor at the University of Southern Mississippi. He is a graduate of both Oregon State and Syracuse University that now calls Houston home. Now that he is retired from TV, he maintains this blog in his spare time.