PINE BELT (WDAM) - Hurricane Irma is still moving west at 15mph across the Atlantic. It now has wind speeds at 185mph. That makes it a Category 5 storm. This is how it looks on the GOES-16 satellite:
Yup. Still not a Category 6. Because, well, that doesn't exist. And won't until (if they ever even do?) they revamp the scale. As usual, here is an objective look – in plain English – at the storm and what you need to know about it. Because we are all on pins and needles after Harvey, the last thing we need is hyperbole. So here is a #nofilter look at everything Irma.
Still borrowing a line from former United States Secretary of Defense Donald Rumsfeld, we are going to look at the known knowns. The known unknowns. And the unknown unknowns.
As stated above, Irma is a Category 5 storm with wind speeds at 185mph. The minimum centralized pressure is 926mb. Hurricane-force winds extend outward up to 60 miles from the center and tropical-storm-force winds extend outward up to 175 miles.
This storm is much bigger than just a few days ago when the sustained hurricane-force wind was only 10 to 20 miles out from the center. The National Hurricane Center is doing a great job with the forecast.
And they have issued watches and warnings for islands in the Atlantic ahead of this storm.
From the NHC:
Irma is forecast to begin to shift west-northwest overnight tonight and will move through the above-mentioned areas. It move over portions of the northern Leeward Islands tonight and early Wednesday, move near or over portions of the northern Virgin Islands Wednesday, and pass near or just north of Puerto Rico late Wednesday and Wednesday night. Areas that are closeest to the center of the storm and get hit by the eyewall will deal with estimated wind speeds of 185mph with gusts even higher. That is comparable to an EF-4 tornado. At the same time,, storm surge of seven to 11 feet is anticipated in St. Croix on the Virgin Islands. Three to five feet of surge on the northern side of Puerto Rico. One to two feet on the southern side. More from the NHC:
We know this is a dangerous storm and people in the Caribbean islands mentioned need to make plans to protect life and property ahead of this storm.
1. Placement of ridge of High Pressure in the Atlantic
2. Strength of ridge of High Pressure in the Atlantic
3. Placement of the trough in the eastern 2/3 of the US later this week
4. Influence of Typhoon Sanvu on the jet stream
I'm adding a few things that may also change some things, too:
5. Placement of a lingering area of mid-level low pressure behind the trough mentioned above
6. Strength of that mid-level low
7. How close Irma gets to the islands of Puerto Rico, the Dominican Republic/Haiti, and Cuba
While we are stating to get a better idea of 1, 2, 3, and 4 due to the great work by the Hurricane Hunters, we still won't have a good picture of what we are looking at until 48 to 72 hours out. As for 5 and 6, those are new wrinkles pointed out best by Philippe Papin.
The idea is that the relationship between the size and strength of the left-pver mid-level low (numbers 5 and 6 above) and the area of High Pressure in the Atlantic (numbers 1 and 2 above) will dictate the exact track. But until we get closer, this is still a known unknown. And something we will all be watching closely. And the above-mentioned relationship is then also contingent on the results of the number 7 above, too. If Irma tracks over every single island it will likely slow a bit more and weaken. The weaker it gets the more that may change the overall tendencies the storm has to follow the steering flow. So, in a nut-shell, it is complicated. Models are still struggling to figure out (meteorologists call this "struggling to resolve") what will happen given these different scenarios.
There are other differences between the American (GFS) and European (ECMWF) models. And then differences between those and the shorter-term models like the HWRF, HMON and TABS, TABM, TABD models. Some have struggled with outcomes, too. The good news? The Hurricane Hunters continue to take readings and collect data in and around Irma. That added data is helping those above-mentioned models create better forecasts. What those better forecasts look like are also something that we know that we don't know. I will say, though, it is probably encouraging for folks in Louisiana, Mississippi and Alabama to see very few lines on those models pointing toward them. For folks in Florida and Georgia, please keep a VERY close eye on this storm.