Since 2012 on the now retired Weather Underground blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at 

  • NCHurricane2009


Updated: Sep 28

*******Note that forecast and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********


The east side of Hurricane Ian has been producing multiple radar rotation signatures and tornado warnings across south Florida as of this afternoon and evening. Vertical wind shear favoring tornadoes is on the east side of the hurricane due to the surface southerly flow below a layer of upper southwesterly flow in advance of the amplified upper trough currently over the eastern United States. This pattern is expected to continue across the Florida peninsula over the next day or so as Ian moves slowly and as upper southwesterly flow persists. If in the Florida peninsula... be sure to watch local news feeds to be aware of tornado warnings over the next day or so... if under a warning take shelter in the interior-most room and lowest-level of your building. See more complete update below from 1:50 PM EDT for other hazards to consider across the Florida peninsula.

...TUESDAY SEPTEMBER 27 2022 1:50 PM EDT...

Major Hurricane Ian emerging offshore of northwestern Cuba and into the southeastern Gulf of Mexico while intact... upper-level winds continue to remain favorable for further intensification of the category 3 hurricane and Ian is expected to become a category 4 later today. The following is a special update to increase my intensity forecast for the storm. See full update #113 available on the home page of this site for information regarding the rest of the Atlantic tropics.

MAJOR HURRICANE IAN... Left... colorized infrared satellite image as Ian's eye made landfall in western Cuba overnight. Right... true-color visible satellite image of Ian which shows an intact and healthy hurricane emerging into the southeastern Gulf of Mexico from western Cuba:

Ian's eye crossed over the western Cuban mainland early this morning while strengthening to a peak of 125 mph maximum sustained winds. The land interaction weakened Ian just slightly to an estimated 115 mph maximum sustained winds with the central surface pressure climbing from the 950s of mb to now 961 mb. Ian's eye is now over the southeastern Gulf of Mexico with ominous signs of re-strengthening... with the eye clearing out on visible and infrared satellite imagery and a symmetric core of thunderstorms around the eye. The circular structure of the hurricane indicates that is is not yet sheared by the upper southwesterly flow ongoing out ahead of the strong upper trough currently over the eastern United States. Instead this flow continues to ventilate the north side of the hurricane by pulling air away from the top of the storm... which will only help Ian's surface pressure fall back down. This special update is to raise the intensity forecast... and also the latest model data and current observations require some small adjustment to the track forecast as follows:

The latest satellite loops show that Ian's eye has an eastward angle in its northward track... and the updated forecast track listed below is nudged eastward. Ian is moving north in response to the surface ridge weakness over the eastern US being generated by the eastern divergent side of the upper trough mentioned in the previous paragraph. Toward the mid and latter part of the 5-day forecast period... models agree that the upper trough and associated surface ridge weakness will gradually lift northeastward and away... trapping Ian south of a potent surface ridge that builds under the western convergence zone of the amplified departing upper trough. In addition the upper trough is expected to leave behind a cut-off trough over the southeastern US. Ian's northward speed is expected to slow in the 24 to 48 hour timeframe...a combination of Ian being embedded in steering upper southerly flow ahead of the leftover cut-off upper trough while the potent surface ridge resists Ian's northward progress. Using the latest current observations... models now suggest the departing upper trough will break up into smaller pieces of upper vorticity... resulting in a slightly longer time for the whole upper trough system to depart. That means the blocking surface ridge supported by the convergent back side of the upper trough system could remain north of Ian for an additional 12 hour period... and really we could be talking about Ian drifting slowly north in the 24 to 60 hour window instead of 24 to 48 hours. This will only worsen the prolonged exposure to wind... coastal storm surge... and flash flooding heavy rainfall over west-central and northwestern parts of the Florida peninsula. Once the departing main upper trough system and blocking surface ridge finally do depart eastward... the northward forward speed of Ian in the late part of the forecast period is increased.

Regarding the intensity forecast... the NHC as of this writing still shows Ian becoming a category 4... but just a little weaker than their prior forecast while projecting at 130 mph maximum sustained wind peak. Based on the latest satellite appearance of Ian... I think this could be a little too low and I now forecast Ian to explosively intensify into a higher-end category 4 with 150 mph maximum sustained winds in the next 12 hours. After that time Ian's core will move directly into the upper southwesterly flow which should shear it... and so I predict weakening after the 12 hour mark. The shear will only be exacerbated as Ian slows down and falls behind the upper southwesterly wind speed. However for those in west-central Florida... do not let your guard down as Ian's short-term strengthening will result in it needing time for its winds and coastal storm surge to wind down... therefore life-threatening coastal storm surge and damaging winds are still on the table. Also noteworthy... I have extended the amount of time Ian remains an inland tropical storm as it lumbers across northern Florida and southern Georgia. This is a result of a potentially favorable interaction between Ian and the leftover cut-off upper trough over the southeast US. The northerly surface flow on Ian's west side may help to pull cool air associated with this trough southward... helping to amplify the trough. An amplifying adjacent warm core central US upper ridge wave to be bolstered by the warm sector of a western US frontal system may also amplify the trough... with increased divergence on the east side of the more amplified trough helping Ian. The slight eastward adjustment in the forecast track is such that Ian could be centered still inland but now close enough to the Georgia coast such that tropical storm wind could occur along and just offshore of the coast where frictional effects from land are less... resulting in Ian hanging on to its tropical storm status for a bit longer.

Regarding impacts to land areas:

(1) Weather conditions and coastal surf across western Cuba will gradually improve for the remainder of the day as Ian lifts northward and away.

(2) For the Florida Keys... the core of what is expected to be a major category 4 Hurricane Ian will pass just to the west by this evening. Coastal storm surge and strong wind is anticipated as the eastern core and rain bands of the hurricane pass over... with impacts being most severe in the westernmost keys. Preparations here should have been completed by now... if not then being rushed to completion.

(3) For the Florida peninsula... the east side of Ian is expected to overspread the area this evening further south... and the entire peninsula by Wednesday. The expected slow down in the forward speed will subject the peninsula to prolonged impacts such as high rainfall totals creating a risk of major flash flooding... do not drive your car into a water-covered roadway if you encounter one. Ian's center is expected to be located just offshore of the west coast of the peninsula... subjecting this side of coastline to a long period of onshore pushing wind and coastal storm surge. Based on the latest forecast track... the largest potential for damage from prolonged exposure to hurricane-force wind and storm surge on the west coast is from the Tampa Bay area and points north. The east side of peninsula could also be near enough to Ian's center to experience tropical storm force gusts with some damage potential... particularly north of Miami all the way to the Florida/Georgia border. Continue preparing now for the above-listed impacts... and I recommend preparations finish by this afternoon.

(4) For the Florida panhandle... expect coastal surf across all of the panhandle... and tropical storm force winds with some damage potential in the eastern half of the panhandle by late Wednesday and Thursday. The eastern half of the panhandle may also see a prolonged period of heavy rainfall with significant flash flooding potential due to the storm's forecast slow motion. Prepare now... and finish preparing by Wednesday afternoon at the latest.

(5) Southern Georgia can expect a prolonged period of heavy rainfall with significant flash flooding potential due to the storm's forecast slow motion... as well as tropical storm force winds with some damage potential by late Thursday through Friday. Along Georgia's coast... gusty winds could last through Saturday with the development of coastal surf given Ian's eastward shift in the forecast track which may allow it to be centered still inland but near enough to the coast to keep some of its strength where land friction will be less. Prepare now... and finish preparing by Wednesday afternoon at the latest.

(6) Some heavy rainfall with isolated flash flooding potential is possible for northern Georgia and the Carolinas by Sunday if the current forecast holds. The east shift in the long range track reduces Ian's rainfall potential in eastern Tennessee.

The following are recent wind reports at National Weather Service stations in south Florida... listed in mph. Observe that tropical storm force wind (40+ mph) is beginning to move into the western Florida Keys.

**Key West FL... sustained 29... gust 43... now

**Key West FL... sustained 31... gust 46... 11:53 AM EDT

**Marathon FL... sustained 22... gust 36... now

**Fort Lauderdale FL... sustained 26... gust 36... now

**Naples FL... sustained 14... now

****** forecast. Visit (hurricanes dot gov) for official forecast***********

0 Hr Position (1200Z Sep 27)...115 mph maximum sustained wind major hurricane centered just offshore of the northwest Cuban coast at 23N-83.5W

IOH 12 Hr Forecast (0000Z Sep 28)...150 mph maximum sustained wind major hurricane centered just northwest of the Florida Keys at 25N-83W

IOH 24 Hr Forecast (1200Z Sep 28)...115 mph maximum sustained major hurricane centered just offshore of the southwestern coast of the Florida peninsula at 26.2N-83W

IOH 48 Hr Forecast (1200Z Sep 29)...75 mph maximum sustained wind hurricane centered on the west coast of Florida and just north of Tampa Bay at 28.2N-82.5W

IOH 72 Hr Forecast (1200Z Sep 30)...50 mph maximum sustained wind tropical storm centered over the northwestern Florida peninsula at 29N-82.2W

IOH 96 Hr Forecast (1200Z Oct 1)...45 mph maximum sustained wind tropical storm centered over the eastern Florida/Georgia border at 30.5N-82W

IOH 120 Hr Forecast (1200Z Oct 2)...Remnant low centered over the Georgia/South Carolina border at 32.5N-81.8W

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