First Alert Weather

Talking the Tropics With Mike: Powerful Idalia makes landfall on the Big Bend of Florida

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REMEMBER WHEN A TROPICAL STORM OR HURRICANE IS APPROACHING: Taping windows is *not* recommended & will not keep glass from breaking. Instead close curtains & blinds.

Realize the forecast cone (”cone of uncertainty”) is the average forecast error over a given time - out to 5 days - & *does not* indicate the width of the storm &/or where damage that might occur.


* “Idalia”: Impacts centered on Wednesday...

* Hurricane Franklin: Rip currents & an easterly swell (waves) at the beaches through Tue. while 1,000+ miles to the east of Jacksonville

The Atlantic Basin Overview:

“Idalia” made landfall on the Florida Big Bend a little before 8am Wed.

A Storm Surge WARNING: Englewood northward to Indian Pass, including Tampa Bay ... St. Catherine’s Sound to South Santee River. A Hurricane WARNING: Middle of Longboat Key northward to Indian Pass, including Tampa Bay ... Altamaha Sound Georgia to Edisto Beach South Carolina. A Tropical Storm WARNING: Chokoloskee northward to the Middle of Longboat Key ... West of Indian Pass to Mexico Beach ... Sebastian Inlet Florida to Surf City North Carolina. A Storm Surge WATCH: Bonita Beach northward to Englewood, including Charlotte Harbour ... Mouth of the St. Mary’s River to St. Catherine’s Sound Georgia ... Beaufort Inlet to Ocracoke Inlet North Carolina ... Neuse and Pamlico Rivers North Carolina. A Hurricane WATCH: Mouth of the St. Mary’s River to Altamaha Sound ... Edisto Beach to South Santee River

Meanwhile...“Franklin” hit Haiti & especially the Dominican Republic with very heavy rain last Wed. The hurricane rapidly intensified to a high end Cat. 4 Monday when the storm finally found the “sweet spot” of the SW Atlantic but at least is not a threat to land. There will be some distant impacts (waves & rip currents) on the U.S. east coast through midweek. Franklin will accelerate to the north/northeast, & there will be some impacts for Bermuda Tuesday but *not* a direct hit on the island. A turn toward the northeast over the NW Atlantic looks be sharp enough to keep most impacts east of Canada.

And tropical depression #11 formed Tue. morning over the Central Atlantic but will not likely be around long.

(1) The area of disturbed weather near the Yucatan - Tropical depression #10 - strengthened into tropical storm “Idalia” late Sunday morning & the third hurricane of the ‘23 Atlantic season early Tuesday... & steadily strengthened overnight into early Wed. with a peak at Cat. 4 Tue. night before making landfall early Wed. - about 7:50am - during an eyewall replacement cycle. This cycle along with friction from land helped begin a slight & slow weakening trend while moving ashore. The eye will continue northeast across Southern Ga. through Wed. moving offshore near Charleston early Thu. shortly after midnight.

Local (Jacksonville/NE Fl./SE Ga.) Impacts (BASED ON CURRENT FORECAST & SUBJECT TO CHANGE) centered on Wednesday with rapid improvement Wed. night/Thu.:

Rain - An average of 2-4″, locally more west of Highway 301.... 1″(+) from Highway 301 to the beaches. The fast movement of Idalia will keep amounts lower than what’s often experienced w/ tropical cyclones. The area has also been unseasonably dry the last few weeks so there is not an overly large amount of water “in the system” which will help some when it comes to fresh water flooding. In the end, water wont be a big deal for most neighborhoods, towns & cities.

Winds - averaging 30-50+ mph west of Highway 301 with gusts 65+ mph. Closer to I-75 - from Lake City to near & south of Waycross eastward to Nahunta to near & north of Brunswick - sustained winds near hurricane force of 60-70 mph can be expected with hurricane force gusts 75+ mph will be possible. From Highway 301 to the beaches of NE Fl., sustained winds Wed. averaging 25-40 mph with gusts 45+ mph, a few gusts 50-60+ mph at the coast.

Direction: winds will be out of the south by early Wed. veering to out of the SW in the afternoon then out of the west & eventually NW (offshore) by evening into the overnight.

Bridges: local protocol is a bit wishy-washy to say the least regarding the threshold to close bridges in Duval Co. & surrounding areas. For the most part the threshold has always been sustained winds of 40 mph. But that’s not across the board & sometimes closing a bridge is based on sight or even feel. So the forecast - & real-time - winds may or may not translate into whether or not bridges are ultimately closed.

Coast/beaches/intracoastal of NE Fl.: windy with winds of 30-45 mph & gusts 50-60+ mph. There will be a high rip current risk enhanced by distant hurricane Franklin & an easterly swell. A full moon Wed. evening will also give an astronomical boost to surf. Based on the current forecast, this should not be particularly severe for our beaches from an erosion standpoint (compared to Nicole & Ian from last year, for example). Seas will peak at an average ~6-9 feet Wed. with surf averaging 4-7 feet, locally higher. The best advice is to stay out of the ocean through at least Thu. but if you do insist on going in the water, always swim & surf with a buddy & as close to a lifeguard as possible. Winds will become offshore & “clean up” the surf by late Wed./Wed. night but with a continued high & dangerous risk of rip currents.

Storm surge is forecast to average 1-3 feet along the NE Fl. coast & St. Johns River... & 2-4 feet for the coast of Southeast Georgia (far lower than previous storms Matthew, Irma, Ian & Nicole).

St. Johns River: Based on the latest forecast... strong winds from the south will push water northward to downtown causing potential flooding, but not likely extensive & not to the extent of Nicole last year & certainly not to the extent of Irma in ‘17. Once the center of Idalia moves by & away, strong winds on the backside out of the west & northwest will help to “empty” some of the water to the east. All areas along the river & its tributaries - from Putnam Co. through Clay/St. Johns & Duval Co. will be subject to some flooding & backwash. Unique & varied topography along the river, intracoastal & coast can & will lead to localized higher surge & flooding. As a whole, storm surge is forecast to average 1-3 feet which - as just mentioned - is *below” the levels of Nicole & Ian last year & well below Irma in ‘17 & Matthew in ‘16.

Tornadoes: Isolated tornadoes can be expected into early Wed. afternoon.

Damage: Idalia’s winds will be the biggest threat along with a few tornadoes. The most widespread & significant wind damage potential looks to be west of I-95 & especially west of Highway 301 to near I-75 north across much of SE Ga. so largely an inland storm. At least some power outages can be expected & may be fairly long lasting in some areas with highest likelihood for longer term & more widespread loss of power near & west of Highway 301 or well inland.

Travel & Infrastructure Thursday after the passage of Idalia: I expect most roads, businesses & airports to be able to operate rather “normally” by Thursday [if they want to/choose to] across most of Northeast Florida along the I-95 corridor to the beaches. It does not appear damage will be widespread from Wednesday’s winds but there will be some downed trees & tree limbs, some power outages & some ponding of water though - again - water does not look to be a big issued with Idalia. Virtually all highways & interstates should be pretty clear rather quickly.

Of course, the exception will be west of Highway 301 & much of Southeast Ga. If traveling west or northwest to NW Florida, the Eastern Panhandle &/or Southern Ga., some highways may be impassable. These areas will be much closer to the center of Idalia & will correspondingly suffer more severe damage. And some of this heavier damage will include Waycross, Blackshear, Nahunta & Fargo, Ga. - all within the Action News Jax CBS47/Fox30 Action News Jax viewing area.



Forecast Discussion: After meandering most of Sunday, Idalia turned northward, has organized & is starting to pick up its forward speed. With a core becoming established, Idalia rapidly intensified. Idalia will move northeast - while accelerating - turning more E/NE across Southern Ga. through early Wed. evening.

Idalia will move off the coast of the Carolina’s shortly after midnight Wed. night.

Based on the latest forecast:

Track: The upper Big Bend of Florida is where landfall occurred. Weakening will be slowed because of otherwise favorable meteorological conditions (high atmospheric moisture content, strong upper level “ventilation” + the fast movement means Idalia could still be a hurricane for much of its journey inland all the way to the Atlantic! Once offshore, it appears the upper level trough will “lose” Idalia & the storm may meander over the W. Atlantic through much of next week. In fact, the GFS model - & now some other global models as well - shows a return to Fl. mid next week as a weak system (”Ivan” pulled of a similar stunt in 2004).

Timing: Accelerating to the north/northeast into Wed. Highest impacts on Florida through late Wed. Winds will diminish west to east through Wed. night/early Thu.

Strength: since Idalia is over land, weakening will continue though it appears Idalia will make move through SE Ga. as a high end Cat. 1, possibly still as a Cat. 2 hurricane then exit as a Cat. 1 hurricane or strong tropical storm.

Summary:. The biggest impacts will be from approximately the Central/Eastern Panhandle to the Big Bend to north of Tampa on the west coast of Fl. There will be lots of folks traveling late in the week with Labor Day weekend just around the corner so stay up to date on the latest forecasts, but it does appear that Idalia will have cleared the U.S. by at least Fri. though may linger east of the Carolina’s but offshore into the weekend. Don’t focus too much on the center of the storm as impacts will be far away from the center point of Idalia including a storm surge possibly near half a foot for Tampa Bay. Travel west on I-10 from Lake City to the Eastern Panhandle will be difficult at best. High winds will likely down trees & power lines & cause property damage across a good part of Southeast Ga.

Once over the W. Atlantic, a loop back to the south & then southwest will be *possible* next week, but Idalia looks to be a good deal weaker at that point & - while interesting & topical - I would expect whatever is left of Idalia will be much weaker. Some forecast models simply slow Idalia over the Atlantic while meandering (rather then make the full turn to the southwest). Such tracks have occurred before, by the way as Ivan in 2004 powered though the Western Fl. Panhandle then looped across the Eastern U.S. to the Atlantic before turning southwest then west & moving back across South Fl. - much weaker but Ivan literally went full circle.

Spaghetti plots including ensemble (instead of running just a single forecast, the computer model is run a number of times from slightly different starting conditions. The complete set of forecasts is referred to as the ensemble, and individual forecasts within it as ensemble members.) “Idalia”:

Peak storm surge forecast in feet above ground level - double digits in sparsely populated Big Bend area:

The times below correlate with “most likely” arrival time of winds equal to or greater than 39 mph:

Brighter colors indicate higher probabilities of winds greater than or equal to 39 mph. Realize any probability above zero is significant considering most days the probability is zero.

Forecast rainfall in inches:

From S. Fl. Water Management District:

Charleston radar:

Tallahassee radar:

Moody AFB radar:

Water vapor loop. Blue color indicates dry mid & upper level air, white & green indicates high moisture levels:

Oceanic heat content is pretty impressive, especially within a narrow ribbon from Cuba through Central to the Northern Gulf:

Forecast rainfall, European model:

Forecast rainfall, GFS model (is forecasting landfall farther to the west):

(2) “Franklin” (upgraded late last Sunday) over the Northern Caribbean becoming a powerful hurricane east of the Bahamas over the SW Atlantic making the sharp turn to the north. The combination of lessening shear plus strong upper level diffluence thanks to a trough of low pressure to the north with very warm water below helped intensify Franklin to a Cat. 4 Monday. There will be some impacts for Bermuda into Wed. as the eye moves by to the west & north but not a direct hit on the island. Franklin should take a sharp enough turn to the east to *not* have significant direct impacts on Canada with the possible exception of some wind + rough seas & surf for far Eastern Newfoundland & Labrador.

Franklin will also be strong enough - while still well to the east of Florida - to produce an easterly swell at area beaches resulting in a heightened rip current risk all up & down the U.S. eastern seaboard through Wed. into at least Thu. A full moon will also add an astronomical boost to seas & surf.

The forecast track is pretty straight forward with a well established alleyway across the Western Atlantic with Franklin accelerating over the next several days while maturing then bending rather sharply to the northeast.

A Tropical Storm WARNING is in effect for Bermuda

(3) Tropical depression #11 has formed over the Central Atlantic & is expected to be short-lived. No threat to any land areas.

(4) And yet another tropical wave is moving west off the coast of Africa. Some gradual development will be possible over the open E. Atlantic.

Check out the upper oceanic heat content (UOHC) [tropical cyclone heat potential/TCHP] across the SW Atlantic, Gulf & Caribbean. The warmth is very deep. But keep in mind warm ocean temps. alone doesn’t necessarily equate to a “big” hurricane season (need other ingredients & factors to be favorable too) but it’s obvious there is a lot of very warm water at great depths over the Caribbean & Gulf of Mexico:

Water vapor loop (dark blue/yellow is dry mid & upper level air):

July tropical cyclone origins:

Averages below based on climatology for the Atlantic Basin for August:

Wind shear:

Saharan dust spreads west each year from Africa by the prevailing winds (from east to west over the Atlantic). Dry air - yellow/orange/red/pink. Widespread dust is indicative of dry air that can impede the development of tropical cyclones. However, sometimes “wanna’ be” waves will just wait until they get to the other side of - or away from - the plume then try to develop if other conditions are favorable. In my personal opinion, way too much is made about the presence of Saharan dust & how it relates to tropical cyclones. In any case, the peak of Saharan dust typically is in June & July.

2023 names..... “Jose” is the next name on the Atlantic list (names are picked at random by the World Meteorological Organization... repeat every 6 years). Historic storms are retired [Florence & Michael in ’18... Dorian in ’19 & Laura, Eta & Iota in ‘20, Ida in ‘21 & Fiona & Ian in ‘22]). In fact, this year’s list of names is rather infamous with “Katrina”, “Rita” & “Wilma” retired from the ‘05 list & “Harvey”, “Irma”,“Maria” & “Nate” from the ‘17 list. The WMO decided - beginning in 2021 - that the Greek alphabet will be no longer used & instead there will be a supplemental list of names if the first list is exhausted (has only happened three times - 2005, 2020 & 2021). The naming of tropical cyclones began on a consistent basis in 1953. More on the history of naming tropical cyclones * here *.

East Atlantic:

Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear:

Water vapor imagery (dark blue indicates dry air):

Deep oceanic heat content over the Gulf, Caribbean & deep tropical Atlantic. The brighter colors are expanding dramatically as we near the peak of the hurricane season.:

Sea surface temp. anomalies:

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:


GFS wave forecast at 48 & 72 hours (2 & 3 days):

Atlantic Basin wave period forecast for 24, 48 & 72 hours respectively:

East/Central Pacific:

I wrote about “Hilary” near the top after the Atlantic waves. Elsewhere.....

Irwin” to stay over the open E. Pacific:

West Pacific:

Global tropical activity:

“Saola” is a formidable typhoon not far from the Philippines while making a loop & moving very slowly & may eventually - by Wed. into Thu. - move just south of Taiwan.


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