This update is based on information from the National Hurricane Center’s 5PM advisory on Hurricane Irma.
Current Situation
Hurricane Irma continues to persist as a large and powerful Category 4 storm with peak sustained winds of 155 mph. Its eye still appears somewhat ragged, suggesting that it’s still undergoing an eyewall replacement cycle. This will continue to lead to fluctuations in its strength.
Headlines
Track forecast continues to edge westward. This decreases the risk Irma poses in any direct way to Georgia and South Carolina coastal areas, though storm surge threat here is still significant.
The threat of a direct hit on Miami is decreasing. However, a track to the west of Miami would result in the South Florida region being on the more dangerous eastern side of the storm.
The risk of devastating impacts to the west coast of Florida is increasing.
Irma’s eye may be moving very close to or make landfall on the northern Cuban coast. The threat of catastrophic wind and storm surge damage to Cuba’s north shore is increasing.
Risk of damage from flooding rains and tornadoes also exists. See this 1-5 day map of possible rainfall totals:
Forecast Track
Forecast models continue to edge slightly westward on a track for Irma and as such the National Hurricane Center has also adjusted its latest forecast slightly more west.
Forecast Intensity
National Hurricane Center forecasts continue to call for Irma to make landfall somewhere in South Florida as a very dangerous and powerful Category 4 storm. Outside of possible internal fluctuations and interaction with Cuba’s high terrain, there are no other inhibiting factors on Irma maintaining Category 4 strength of even possibly intensifying. Irma is entering an area of very warm sea surface temperatures with basically no mid-level wind shear.
We’ve got a wonderful stretch of below average but sunny, fall-like weather ahead of us over the weekend. The main weather story lies far to our south as Florida braces for Hurricane Irma over this same time period. Irma has weakened a bit but is still a large and dangerous Category 4 storm capable of wreaking havoc over the entire state of Florida.
Rest of today – our weather will be dictated by an area of high pressure anchored over the Great Lakes. This will give us mostly sunny skies with a cool high in the mid-70s.
High pressure firmly in control of the weather in our part of the world. You can see Hurricane Irma making its finally approach on Florida in the lower right.
Saturday – sunny with temperatures in the low-70s as the high pressure over the Great Lakes moves east a bit.
Sunday – more of the same as Saturday with sunny skies and high temperatures in the low-70s.
Monday – slightly warmer with high temperatures creeping back into the mid-70s with some more clouds.
Hurricane Irma a Major Threat to South Florida
Current Situation
Hurricane Irma has been weakening in the last 12 hours. It’s evident the storm is undergoing an eyewall replacement cycle, where the inner eye of the storm collapses and is replaced by a larger, outer eye. During these internal cycles, max wind speeds often decrease and fluctuate before the storm consolidates a new eye. It has been downgraded to a Category 4 storm with maximum sustained winds of 150 mph.
Headlines
Landfall somewhere in South Florida over the weekend is a near certainty. Outer bands from Irma are expected to reach South Florida overnight tonight. Life-threatening storm surge inundation and damage from winds of major hurricane force (115 mph) are a near-certainty for parts of South Florida.
Since midday yesterday, forecast models have trended slight back towards a westerly solution for the forecast track of the storm. This almost eliminates the risks to Georgia and South Carolina coastal areas from a direct hit from a major hurricane. However, the risk to these areas from storm surge and strong tropical storm force/marginal hurricane force winds still exists.
There is still a chance Irma could make landfall on Cuba. This would weaken the storm ahead of subsequent landfall on Florida.
Forecast Track
As mentioned above, the best performing forecast models have shifted back to a more westerly track for Hurricane Irma.
Several different forecast models take on Irma’s track.Official National Hurricane Center forecast as of 8AM today.
Forecast Intensity
While Irma has weakened to a Category 4 storm due to an ongoing eyewall replacement cycle, it remains an extremely dangerous storm with an expanding wind field due to this cycle. Hurricane force winds extend 70 miles on each side of the eye and tropical storm force winds well beyond that. It remains possible that Irma can re-strengthen if it completes the eyewall replacement cycle before it interacts with land. Mid-level wind shear remains negligible and Irma will soon be passing over very warm seas with increasing depth. Both of these factors would suggest it maintaining Category 4 strength or possibly re-intensifying to Category 5.
Uncertainties
Any landfall on Cuba or interaction of the core of the storm with the high mountains of that island would disrupt the storm and cause weakening. This would be good news for Florida, at the expense of Cuba of course.
Should the core of the storm avoid Cuba and close off a new eye before too much time elapses, it would have the possibility of re-strengthening before landfall. A strong Category 4 or even a Category 5 storm making landfall on Florida is not out of the question.
