Irma Turning Into Monster Hurricane: "Highest Windspeed Forecasts I've Ever Seen"

Hurricane Irma continues to strengthen much faster than pretty much any computer model predicted as of yesterday or even this morning.  Per the National Hurricane Center"s (NHC) latest update, Irma is currently a Cat-3 storm with sustained winds of 115 mph but is expected to strengthen to a devastating Cat-5 with winds that could top out at 180 mph or more.  Here is the latest from the NHC as of 5PM EST:

Irma has become an impressive hurricane with intense eyewall convection surrounding a small eye.  Satellite estimates continue to rapidly rise, and the Dvorak classifications from both TAFB & SAB support an initial wind speed of 100 kt.  This is a remarkable 50-kt increase from yesterday at this time.

Irma continues moving west-northwestward, now at about 10 kt. There has been no change to the forecast philosophy, with the hurricane likely to turn westward and west-southwestward over the next few days due to a building ridge over the central Atlantic.  At long range, however, model guidance is not in good agreement on the strength of the ridge, resulting in some significant north-south differences in the global models.  I am inclined to stay on the southwestern side of the model guidance, given the rather consistent forecasts of the ECMWF and its ensemble.  In addition, the strongest members of the recent ensembles are on the southern side on the consensus, giving some confidence in that approach.

FORECAST POSITIONS AND MAX WINDS

INIT  31/2100Z 17.3N  34.8W  100 KT 115 MPH

12H  01/0600Z 17.8N  36.2W  105 KT 120 MPH

24H  01/1800Z 18.2N  38.3W  105 KT 120 MPH

36H  02/0600Z 18.3N  40.7W  105 KT 120 MPH

48H  02/1800Z 17.9N  42.9W  105 KT 120 MPH

72H  03/1800Z 16.8N  47.5W  110 KT 125 MPH

96H  04/1800Z 16.0N  52.0W  115 KT 130 MPH

120H  05/1800Z 16.5N  56.5W  120 KT 140 MPH

As of now, Irma remains in the far eastern Atlantic ocean and is moving west at roughly 11.5 mph.  Based on current projections, the storm will make its first landfall in the eastern Caribbean sometime toward the middle of next week.

Longer term computer models still vary widely but suggest that Irma will make landfall in the U.S. either in the Gulf of Mexico or Florida.  Meteorological Scientist Michael Ventrice of the Weather Channel is forecasting windspeeds of up to 180 mph, which he described as the "highest windspeed forecasts I"ve ever seen in my 10 yrs of Atlantic hurricane forecasting."

These are the highest windspeed forecasts I"ve ever seen in my 10 yrs of Atlantic hurricane forecasting. #Irma is another retiree candidate. pic.twitter.com/e6nMsp1myY

— Michael Ventrice (@MJVentrice) August 31, 2017

In a separate tweet, Ventrice had the following troubling comment: "Wow, a number of ECMWF EPS members show a maximum-sustained windspeed of 180+mph for #Irma, rivaling Hurricane #Allen (1980) for record wind"

The Weather Channel meteorologist also calculated the odds for a landfall along the eastern seaboard at 30%.

Up to a 30% chance via the 12Z Calibrated ECMWF EPS for a landfalling Major Hurricane somewhere along the eastern seaboard #Irma pic.twitter.com/nUmZkPGJpY

— Michael Ventrice (@MJVentrice) September 1, 2017

Meanwhile, the Weather Channel has the "most likely" path of Irma passing directly over Antigua, Puerto Rico and Domincan Republic toward the middle of next week.

pic.twitter.com/XTQtUur1PH Nuevo análisis del huracán #Irma por The Weather Channel

— Roberto F. Pardo A. (@robertofaridp) August 31, 2017

"Rapidly Intensifying" Hurricane Irma Barreling Straight Toward The East Coast

The National Hurricane Center (NHC) has just updated its forecast for what it is now referring to as a "rapidly intensifying" Category 2 hurricane in the Eastern Atlantic ocean and the results look disastrous for a large swath of the Caribbean and Southeastern United States.  Here is a brief summary of Hurricane Irma from the National Hurricane Center released at 11AM EST:

Satellite images indicate that Irma is rapidly intensifying. Very deep convection has formed in the central dense overcast, which is now displaying a small and clearing eye.  Dvorak estimates were up to 77 kt at 1200 UTC, and since the cloud pattern continues to quickly become more organized, the initial wind speed is set to 85 kt.

At 1100 AM AST (1500 UTC), the center of Hurricane Irma was located near latitude 16.9 North, longitude 33.8 West. Irma is moving toward the west-northwest near 10 mph (17 km/h).  This general motion is forecast through early Friday, followed by a generally westward motion on Saturday.

Maximum sustained winds have increased to near 100 mph (155 km/h) with higher gusts.  Irma is forecast to become a major hurricane by tonight and is expected to be an extremely dangerous hurricane for the next several days.

Hurricane-force winds extend outward up to 15 miles (30 km) from the center and tropical-storm-force winds extend outward up to 80 miles (130 km).

A 50% chance that the northern Antilles experiences a Hurricane landfall next week; topography may cause models some issues with intensity. pic.twitter.com/ux1YzICbMD

— Michael Ventrice (@MJVentrice) August 31, 2017

Irma is expected to grow into a "major hurricane" within the next 24 hours with maximum sustained winds of 120 mph before growing even stronger throughout the weekend and eventually becoming a Category 4 storm.

The storm is moving west at roughly 10 mph and isn"t expected to pose its first threat to land until next week.

That said, longer term models suggest that Irma could make a turn to the northwest towards the middle of next week and head straight for Florida.

Meanwhile, other computer models predict that Hurricane Irma will move through the Gulf of Mexico and make its U.S. landfall in Texas just 2 weeks after Hurricane Harvey devastated the state.

Major development: The best ECMWF EPS members via initialization score are west of ensemble mean track, taking #Irma into the Gulf of Mexico pic.twitter.com/qT3RQTbZsy

— Michael Ventrice (@MJVentrice) August 31, 2017

That said, a lot could obviously change over the next week and, as the NHC notes, Irma is currently tracking further south than models predicted as of yesterday.

Irma has moved somewhat south of and slower than all of the model guidance since yesterday.  Consequently, it stayed longer over the warmer ocean temperatures away from the drier air to the north, possibly allowing the rapid strengthening.  Irma should move over cooler waters tomorrow with some increase in mid-level dry air, so hopefully the hurricane"s intensity will level off by then.  In a few days, the hurricane will be moving over warmer waters with light shear shown by all of the model guidance.  This should promote further strengthening of Irma, and the NHC forecast shows an extremely dangerous category 4 hurricane next week, similar to the solutions provided by the HWRF and the ECMWF models. The intensity forecast is raised considerably from the previous one due to initial trends, and is on the high end of the guidance at long range.

Of course, with FEMA resources already stretched thin by Hurricane Harvey, another U.S. landfall of a Cat 4 hurricane could be devastating blow.