what was the last category 5 hurricane to hit florida

Hurricane Irma Synopsis

Hurricane Irma was a classic Cape verde hurricane that will long exist remembered for its severity and wide-ranging impacts to several islands in the Caribbean Sea and Florida. Similar many of the most notorious Atlantic hurricanes, Irma began as a weak moving ridge of low pressure level accompanied past disorganized showers and thunderstorms which emerged off the west African coast on Baronial 27^th, about the elevation of the Atlantic hurricane season (Fig. 1). Such disturbances move off the African declension every few days during Baronial and September, however, most of them neglect to develop into tropical cyclones. This can be due to a number of factors, including blasts of dry, stable air from the Saharan desert, stiff upper-level westerly winds, or a lack of the necessary atmospheric "spin" needed to generate a counterclockwise circulation.

In late August and early September, however, the atmospheric and oceanic weather in the tropical Atlantic were favorable for tropical whirlwind development. Bounding main surface temperatures were to a higher place average (generally in the lower to mid 80s F across the tropical Atlantic), and in that location was an area of low-cal winds in the upper atmosphere, which immune the developing tempest circulation to grow vertically deep (Fig. 2).

Fig. 1 National Hurricane Heart's 5-day forecast probability for a tropical disturbance emerging off the westward African coast on August 27th. Image courtesy of NHC.

Fig. ii Upper-level menstruum (white lines with arrows), based on satellite estimates of 200 mb winds (forty,000 ft AGL). Image is vertical current of air shear in knots, with blackness and dark blue beingness well-nigh favorable for tropical whirlwind intensification (i.due east. calorie-free current of air shear). Hurricane Irma shown using cerise hurricane symbol. Prototype courtesy of UW CIMSS.

Tropical Tempest Irma formed in the far eastern Atlantic Bounding main, merely west of the Republic of cape verde Islands, on the morn of August 30^th. Over the following xxx hours Irma intensified into a major hurricane with highest sustained winds of 115 MPH, a category-3 storm on the Saffir-Simpson Hurricane Current of air Calibration. Such rapid strengthening is unusual for storms in the far eastern Atlantic. Irma'southward intensity remained fairly steady for the next few days while moving into a region with drier air aloft (Fig. three)

Fig. 3 Water vapor prototype. Image courtesy of UW CIMSS.

Equally Irma began to approach the northern Leeward Islands on September 4^th and 5^th, the hurricane quickly intensified while moving over warmer water and into a more moist temper. The storm became a rare category-5 hurricane on September v^th, with maximum sustained winds of 185 MPH. This made Irma the strongest hurricane e'er observed in the open Atlantic Sea, and one of only 5 hurricanes with measured winds of 185 MPH or college in the entire Atlantic basin. Over the next few days Irma continued moving due west, passing through the northeast Leeward Islands, Virgin Islands, and only n of the islands of Puerto Rico and Hispaniola, while maintaining its category-v winds. While category-5 hurricanes are rare, information technology is even more than rare for such storms to maintain this status for such a long period of time. Irma was a category-5 hurricane for three days (Fig. 4).

Fig. four Satellite montage of Irma using GOES IR images and NHC advisories. Courtesy of UW CIMSS.

While it volition have time to realize all of the impacts from Irma, some were immediately apparent, even from infinite. Fig. v shows the massive defoliation across some of the Virgin Islands which were struck by Irma at tiptop intensity. The islands, which used to announced green to the special satellite sensor due to their dense coverage of plants and trees, are now brown.

Fig. 5 NASA'south landsat-eight satellite images, before & after Irma.

The tempest finally "weakened" to a category-four hurricane on September 8^th, but still had devastating winds of 155 MPH while moving through the southern Bahamas. Irma intensified to a category-5 level once once more that evening, with top winds of 160 MPH, every bit it approached the northern coast of Cuba. Irma moved w forth or just inland from the northern coast of Cuba on September 9^thursday. This interaction with land disrupted Irma'southward structure a bit, as a hurricane requires plenty of deep warm h2o beneath the storm's eye to maintain the extremely low pressure and strong winds. Thus Irma weakened slightly to a category-3 hurricane with winds of 125 MPH.

For many days Irma had been steered steadily westward beyond the tropical Atlantic and Caribbean islands past a strong ridge in the mid to upper atmosphere (10k to 30k ft AGL) to Irma's north. The  numerical conditions prediction models, which are used past forecasters to assist them predict the future rails and intensity of hurricanes, had consistently forecast this ridge to weaken somewhere around Florida. However, these models differed as to exactly when or where this would occur, so that Irma's forecast tracks ranged from just off the east coast of Florida to the farthermost eastern Gulf of United mexican states. This breakdown in the loftier pressure level ridge finally began to develop September nine^thursday, and Irma made its much predictable turn to the northwest, into the Florida Straits (Fig. 6).

Fig. 6 Estimated steering currents for Hurricane Irma on the afternoon of September 9th. White lines with arrows indicate management of steering, image indicates forward speed. Annotation Irma's location over the northward declension of Cuba, betwixt the Bermuda ridge to the east and a ridge over the western Gulf of Mexico. The mid-upper trough between these ridges steered Irma to the northwest, then n. Prototype courtesy of UW CIMSS.

Resilient Irma made a final attempt to re-intensify while crossing the open up waters of the Florida Straits. The storm speedily reached category-four intensity with 130 MPH winds early in the morning time of September 10^th, while budgeted the vulnerable Florida Keys. Fortunately for much of the rest of Florida, Irma finally began to encounter unfavorable atmospheric atmospheric condition for hurricanes. The shear, which had been so lite for so long, was rapidly increasing in Irma's path every bit a trough of low pressure adult in the Gulf of Mexico (Fig. 7). Additionally, dry air associated with this trough was beginning to disrupt Irma'southward inner core.

Fig. 7 Upper-level flow (white lines with arrows), based on satellite estimates of 200 mb winds (40,000 ft AGL). Prototype is vertical wind shear in knots, with yellows and reds existence unfavorable for tropical cyclones (i.eastward. strong current of air shear). Annotation Irma's location over southwest Florida on the afternoon of September 10th. Prototype courtesy of UW CIMSS.

The major hurricane made landfall near Marco Isle in southwest Florida effectually 3 pm EDT on September 10^th, as a category-3 storm  with 115 MPH. Naples, Florida reported a superlative wind gust of 142 MPH. Irma moved quickly north, simply inland from the west declension of Florida on September 10^thursday and 11^th. When Irma first adult in the far eastern Atlantic, despite its strength, its current of air field was quite pocket-size. As the tempest approached Florida, however, its wind field expanded dramatically. As Irma striking Florida, tropical tempest force winds extended outward up to 400 miles from the center, and hurricane force winds extended up to lxxx miles. Hurricane force wind gusts (i.e. 74 MPH or more) were reported along much of the east coast of Florida, from Jacksonville to Miami. In addition to the long periods of heavy rain and potent winds, storm surge flooding as well occurred well abroad from the storm heart, including the Jacksonville area, where strong and persistent onshore winds had been occurring for days before Irma's heart made its closest arroyo.

Past the time the minimal hurricane reached northwest Florida (on the morning of September 11^thursday), the wind gusts across south Georgia and northwest Florida were generally in the 45 to 60 MPH range (Fig. 8). Conditions improved rapidly in one case the tempest centre passed by as potent, dry southwest winds aloft made the system asymmetric, with nearly all of the pelting and most of the strongest winds being along and north of the poorly-defined center. Irma weakened to a tropical storm in south Georgia in the afternoon, and further into a tropical depression while moving northward across central Georgia in the evening.

Fig. 8 Measured local wind gusts associated with Irma.

The residents of northwest Florida and south Georgia were fortunate compared to much of the residue of Florida. Had Irma taken its turn to the n slightly later, the center of Irma would have remained offshore the Florida w declension. Irma would still have weakened due to the increasingly unfavorable atmospheric atmospheric condition, but this weakening tendency may have been slower with the centre even so over the warm waters of the eastern Gulf of United mexican states. A slightly more western track could also have allowed for a brief catamenia of onshore winds in Apalachee Bay, increasing the gamble for storm surge. Irma'due south track to the east of Tallahassee resulted in a prolonged period of strong offshore winds, which actually kept the tides in Apalachee Bay lower than normal for much of the issue (Fig. 9).

Fig. 9 Picture show taken by Taylor Canton Emergency Managing director showing the coast of Taylor County on the forenoon of September xith. During this time the stiff offshore winds really caused beneath-normal tides forth the coast of Apalachee Bay. In this moving picture, the Gulf of Mexico waters, which normally covers much of the area shown, appear far away. The tide did come up later in the twenty-four hour period equally the winds shifted from northward to west after the passage of Irma's middle, merely no significant flooding was reported.

Fig. 10 Satellite IR prototype showing Hurricane Irma, ane of the strongest hurricanes ever in the Atlantic basin, nigh peak intensity on the afternoon of September half dozenth, just north of Puerto Rico. Maximum sustained winds are 185 MPH, and central force per unit area is 914 mb on the 5 pm EDT NHC advisory. Image courtesy of UW CIMSS.

Coldest clouds are shown in white, warmest surface temperatures in blue. Notation the perfectly circular cloud design, the warm spot (the eye of the hurricane, where the satellite sensor can "run across" to the warm bounding main surface) surrounded by the symmetrical band of extremely cold (tall) thunderstorm cloud tops, and the fanning out of thin, high-level clouds indicative of air being evacuated from the core of the tempest. This is a textbook epitome of how an intense hurricane appears in a low shear, moist atmosphere with very warm h2o below.

Fig. 11 Satellite IR image showing the heart of Hurricane Irma, as a minimal hurricane, forth the northwest Florida declension just inland from Cedar Key early in the morning of September 11th. Maximum sustained winds are 75 MPH, and primal force per unit area is 965 mb on the 5 am EDT NHC advisory. Image courtesy of UW CIMSS.

Note how the coldest cloud tops (white) are north and east of the storm center. This is due to strong wind shear (from strong southwest winds in the upper atmosphere), and dry air in the mid and upper levels of the atmosphere wrapping into the storm, and the fact that the hurricane's center had been over land for at least 12 hours.

perezwhisair1941.blogspot.com

Source: https://www.weather.gov/tae/Irma_technical_summary

Share this post