Hurricane Idalia

[Floydbuster]

6 minutes ago, GaWx said:

Isn't it more like 32 hours from now til landfall rather than 48 hours?

Probably a little less. I'm thinking 8-10am Wednesday. 

[RU848789]

30 minutes ago, beanskip said:

Coarse maps on Euro annoyingly hard to extrapolate when the 36-hour mark is the key window. 

This might help - the 0Z Euro moved landfall about 15-20 miles NW vs. 12Z today (was 976 mbar, 3 hours earlier)...

[Roger Smith]

I hope the model consensus proves accurate and this doesn't do a Charley-2004 style swerve towards Tampa Bay; in any case the impact there will be considerable given (a) we are closing in on full moon, (b) the track is close enough to permit strong TS level winds to blow for many hours from the south, all pointing to a considerable storm surge into the Bay. 

Even if the track was along the eastern edge of the cone, it would be bad news for the TBSP metro and any further east could be disastrous. An eastward jog means a considerably earlier landfall also. Instead of Wednesday morning near Cedar Key it would be closer to Tuesday midnight around Dunedin FL. Let's hope this does not happen. 

[SluggerWx]

Lighting in the core of Idalia now in last 4 frames from GOES. You can also see some towers going up.

Sent from my Pixel 6 using Tapatalk

[HillsdaleMIWeather]

Officially a Hurricane 

Nice blowup going on rn

[WxSynopsisDavid]

Finally appears that the centers are aligned and stacked. Vertical column significantly healthier and less tilted. Idalia now into the southern Gulf…and rapidly getting symmetrical. Idalia has that look now, as soon as the eye clears this thing bombs. Hopefully it’s when we have recon inside the storm.

[LovintheWhiteFluff]

000
WTNT45 KNHC 290859
TCDAT5

Hurricane Idalia Discussion Number  11
NWS National Hurricane Center Miami FL       AL102023
400 AM CDT Tue Aug 29 2023

Radar data from western Cuba indicates that Idalia is becoming 
better organized.  Most of an eyewall has formed, with much more 
curvature in the banding features and overall radar pattern.  
Satellite imagery also shows the center of Idalia firmly within the 
central dense overcast.  Thus, the initial wind speed is raised to 
65 kt, in accordance with the latest TAFB satellite classification.

The hurricane is accelerating northward this morning, now moving at 
about 9 kt.  Idalia should move faster to the north or 
north-northeast through landfall on Wednesday between mid-level 
ridging over Florida and a trough dropping into the western Gulf of 
Mexico.  There has been a westward shift in the model guidance 
overnight, perhaps due to the trough tugging Idalia more 
northward before taking a north-northeast turn.  It should be 
noted that the ECMWF ensemble shows many of its strongest members 
on the eastern side of its guidance envelope, which is a 
reasonable place to be given the synoptic pattern.  The new NHC 
forecast is adjusted a little to the west but is now east of the 
model consensus on the eastern side of the reliable model guidance. 
After Idalia leaves the eastern United States coastline, the track 
forecast becomes highly uncertain and little change was made to the 
previous forecast.  

With an inner core now present, the stage is set for Idalia to 
rapidly intensify before landfall. Shear should continue to lower 
over the cyclone as an upper-level trough departs the northeastern 
Gulf of Mexico and ridging builds closer to the cyclone.  These 
changes, combined with extremely warm and deep waters the hurricane 
will be traversing, all strongly point to rapid intensification.  
The new forecast is similar to the previous one, and confidence is 
increasing in an extremely dangerous major hurricane making landfall 
Wednesday along the west coast or Big Bend region of Florida.

KEY MESSAGES:

1. There is a danger of life-threatening storm surge inundation
along portions of the Florida Gulf Coast where a Storm Surge Warning
is in effect, including Tampa Bay and the Big Bend region of
Florida. Inundation of 8 to 12 feet above ground level is expected
somewhere between Chassahowitzka and Aucilla River.  Residents in
these areas should follow any advice given by local officials.

2. Hurricane conditions are expected within portions of the
Hurricane Warning area along the Florida Gulf Coast, with the
potential for destructive winds where the core of Idalia moves
onshore. Strong winds will also spread inland across portions of
northern Florida near the track of the center of Idalia.

3. Heavy rainfall is expected across portions of western Cuba and 
may produce areas of flash and urban flooding as well as landslides. 
Areas of flash and urban flooding, some of which may be locally 
significant, are expected across portions of the west coast of 
Florida, the Florida Panhandle, and southern Georgia beginning today 
into Wednesday, spreading into portions of the eastern Carolinas 
Wednesday into Thursday.


FORECAST POSITIONS AND MAX WINDS

INIT  29/0900Z 23.1N  85.0W   65 KT  75 MPH
 12H  29/1800Z 24.9N  84.8W   85 KT 100 MPH
 24H  30/0600Z 27.8N  84.3W  105 KT 120 MPH
 36H  30/1800Z 30.6N  82.9W   70 KT  80 MPH...INLAND
 48H  31/0600Z 32.7N  80.5W   50 KT  60 MPH...INLAND
 60H  31/1800Z 33.8N  77.5W   50 KT  60 MPH...OVER WATER
 72H  01/0600Z 33.9N  74.4W   50 KT  60 MPH
 96H  02/0600Z 33.3N  71.5W   45 KT  50 MPH
120H  03/0600Z 32.5N  70.5W   40 KT  45 MPH

$$
Forecaster Blake

[LovintheWhiteFluff]

[TriPol]

I'd wager a hefty sum that the likelihood of a landfall event in the Florida Panhandle is rather minimal, a hypothesis that I find somewhat at odds with the current projections from the National Hurricane Center. Since the case of Hurricane Charlie, Gulf-originating hurricanes to veer westward in their tracks, particularly when their initial trajectories are not aimed at Texas, Louisiana, or the Mississippi/Alabama coastline. This westward bias is often less pronounced when a robust anticyclonic system is situated over Florida, effectively serving as a protective barrier for the state's western coastline. One could argue that the NHC's forecasting methodology could benefit from a reevaluation of these recurrent patterns, especially in the context of recent advancements in ensemble forecasting and data assimilation techniques.

[Hotair]

Cuban weather radar indicates the eyewall of Idalia has closed off. Some RI is expected now.  Storm is moving at a healthy 14 mph which is nearly 2x as fast as day prior.  This is good as it limits the amount of uncertainty in the cone. 

[WxSynopsisDavid]

Just now, Hotair said:

Cuban weather radar indicates the eyewall of Idalia has closed off. Some RI is expected now.  Storm is moving at a healthy 14 mph which is nearly 2x as fast as day prior.  This is good as it limits the amount of uncertainty in the cone. 

Faster forward speed also limits the likelihood of eyewall replacement cycles being induced. This means the chances are increasing that Idalia rolls in at peak intensity on landfall.

[dan11295]

Tbh anything within 20 miles or so of current forecast is probably a best case scenario as far as damage. less surge for Tampa, but keeps it E of Apalachee Bay.

[WxWatcher007]

Recon is in the air and will soon provide critical structural and heading data on a strengthening Hurricane Idalia. 

Idalia has remained resilient in the face of moderate shear the last few days, gradually organizing and attempting to fire convection consistent enough to establish an inner core. This morning satellite and radar show that with shear decreasing Idalia is beginning to develop an inner core, with deep convection rotating around the center in the image above and an eye feature evident on radar. 

Recon will be important in assessing just how far along this inner core process has progressed, and whether there is still significant vortex tilting, which can still be possible if there's enough shear still present. My guess looking at the radar however, is that the vortex tilting that was an issue 24 hours ago is no longer enough to keep this from increasing its rate of intensification. 

According to CMISS analysis, shear is now in the favorable zone and expected to remain so until landfall.

As the trough sets up during Idalia's final approach, upper diffluence combined with increasing OHC and SSTs will almost certainly allow for rapid intensification. 

(SST image courtesy of Brian McNoldy)

Once rapid intensification occurs, and it is explicitly forecast by the NHC, we don't know where it'll stop. Time will be a limiting factor, but it cuts both ways. On on hand, there may not be enough time for the very high ceiling for Idalia to be reached. On the other, the lack of time means that a structural change, such as an Eyewall Replacement Cycle (ERC) is less likely. 

There is also modest but meaningful divergence in track.

The consensus among most guidance is to bring this further north, while the European Model and stronger members of the EPS have a further east landfall. It's been talked about around here but we will need to watch for deviations closely, as there are almost always small changes that have a substantial impact on sensible weather.

To be clear--nobody living in the region should merely look at the center track. Heavy rain, storm surge, and strong to destructive winds will be possible far outside the center. Given the parallel run up the west coast of Florida however, where the center landfalls is obviously important for surge and strongest wind impacts. The 06z GFS ticked ever so slightly east relative to 00z. 

Watch the organizational trends, pace of intensification, and the wobbles relative to long term heading.

It should be an active day.

[WxWatcher007]

Didn't add to the post, but recent microwave imagery suggests a nearly completed eyewall. 

[NorthHillsWx]

The only silver lining from the trends this morning is, if the current track holds, the storm could not have found a much more sparsely populated area than where it’s currently forecast to make landfall 

[Eskimo Joe]

 

 

[NERMAN]

1 hour ago, TriPol said:

I'd wager a hefty sum that the likelihood of a landfall event in the Florida Panhandle is rather minimal, a hypothesis that I find somewhat at odds with the current projections from the National Hurricane Center. Since the case of Hurricane Charlie, Gulf-originating hurricanes to veer westward in their tracks, particularly when their initial trajectories are not aimed at Texas, Louisiana, or the Mississippi/Alabama coastline. This westward bias is often less pronounced when a robust anticyclonic system is situated over Florida, effectively serving as a protective barrier for the state's western coastline. One could argue that the NHC's forecasting methodology could benefit from a reevaluation of these recurrent patterns, especially in the context of recent advancements in ensemble forecasting and data assimilation techniques.

I'm not quite sure I follow you? Are you suggesting the current NHC cone area for landfall (say cedar key to big bend) is unlikely to play out?

[WxSynopsisDavid]

8 minutes ago, Eskimo Joe said:

 

 

Good lord that’s a tight, compact eye. If that thing stays looking like a pinhole, I would hate to be the recon hunters having to fly into that sucker later today. 

[WxWatcher007]

Looking at Cuba and now Key West radar you can see an increasingly organized system. That first recon pass and VDM will be very interesting. 

[NERMAN]

28 minutes ago, WxWatcher007 said:

Recon is in the air and will soon provide critical structural and heading data on a strengthening Hurricane Idalia. 

Idalia has remained resilient in the face of moderate shear the last few days, gradually organizing and attempting to fire convection consistent enough to establish an inner core. This morning satellite and radar show that with shear decreasing Idalia is beginning to develop an inner core, with deep convection rotating around the center in the image above and an eye feature evident on radar. 

Recon will be important in assessing just how far along this inner core process has progressed, and whether there is still significant vortex tilting, which can still be possible if there's enough shear still present. My guess looking at the radar however, is that the vortex tilting that was an issue 24 hours ago is no longer enough to keep this from increasing its rate of intensification. 

According to CMISS analysis, shear is now in the favorable zone and expected to remain so until landfall.

As the trough sets up during Idalia's final approach, upper diffluence combined with increasing OHC and SSTs will almost certainly allow for rapid intensification. 

(SST image courtesy of Brian McNoldy)

Once rapid intensification occurs, and it is explicitly forecast by the NHC, we don't know where it'll stop. Time will be a limiting factor, but it cuts both ways. On on hand, there may not be enough time for the very high ceiling for Idalia to be reached. On the other, the lack of time means that a structural change, such as an Eyewall Replacement Cycle (ERC) is less likely. 

There is also modest but meaningful divergence in track.

The consensus among most guidance is to bring this further north, while the European Model and stronger members of the EPS have a further east landfall. It's been talked about around here but we will need to watch for deviations closely, as there are almost always small changes that have a substantial impact on sensible weather.

To be clear--nobody living in the region should merely look at the center track. Heavy rain, storm surge, and strong to destructive winds will be possible far outside the center. Given the parallel run up the west coast of Florida however, where the center landfalls is obviously important for surge and strongest wind impacts. The 06z GFS ticked ever so slightly east relative to 00z. 

Watch the organizational trends, pace of intensification, and the wobbles relative to long term heading.

It should be an active day.

Great write-up. I've been comparing this storm to Michael and there are a lot of similarities in the conditions, path, profile and current status. If it can get to a Cat 2 quickly then it would have more time than Michael needed to make a run at Cat 5. I know it's HIGHLY UNLIKELY because that was a perfect scenario, and I'm not doomcasting or wishing, just throwing it out there the real possibility of intense RI over the next 24 hours. 

[the_other_guy]

1 hour ago, dan11295 said:

Tbh anything within 20 miles or so of current forecast is probably a best case scenario as far as damage. less surge for Tampa, but keeps it E of Apalachee Bay.

Couldnt be better for Tampa metro on current track. Another dodge

[Eskimo Joe]

 

 

[beanskip]

From the top of the TLH AFD:

National Weather Service Tallahassee FL
510 AM EDT Tue Aug 29 2023

...IDALIA EXPECTED TO SLAM THE FLORIDA BIG BEND AS A MAJOR HURRICANE
EARLY WEDNESDAY MORNING...
...New NEAR TERM, SHORT TERM, LONG TERM, AVIATION, MARINE, FIRE WEATHER, HYDROLOGY...

.NEAR TERM...
(Today)
Issued at 504 AM EDT Tue Aug 29 2023

You need to complete your preparations today if you live in the
Florida big bend. To put this system into the historical context,
there are NO major hurricanes in the historical dataset going back
to 1851 that have tracked into Apalachee Bay. None. Don`t mess
around with this. Follow the advice of your local emergency
management.

[beanskip]

It's pretty remarkable that the GFS and all 3 hurricane models show a direct hit on Wakulla and Leon counties -- in a little over 24 hours -- and both counties are only under a Tropical Storm Warning. I worry that an Apalachee Bay hit will catch many off guard. 

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

https://www.tallahassee.com/story/news/hurricane/2023/08/29/hurricane-idalia-updates-for-tallahassee-big-bend-models-track-florida/70705962007/

[WxWatcher007]

First pass from N to S has an extrapolated pressure of 973.9mb at about 10k ft. Awaiting dropsonde and sampling of southern portion of possible eyewall.

[40/70 Benchmark]

1 hour ago, WxWatcher007 said:

Recon is in the air and will soon provide critical structural and heading data on a strengthening Hurricane Idalia. 

Idalia has remained resilient in the face of moderate shear the last few days, gradually organizing and attempting to fire convection consistent enough to establish an inner core. This morning satellite and radar show that with shear decreasing Idalia is beginning to develop an inner core, with deep convection rotating around the center in the image above and an eye feature evident on radar. 

Recon will be important in assessing just how far along this inner core process has progressed, and whether there is still significant vortex tilting, which can still be possible if there's enough shear still present. My guess looking at the radar however, is that the vortex tilting that was an issue 24 hours ago is no longer enough to keep this from increasing its rate of intensification. 

According to CMISS analysis, shear is now in the favorable zone and expected to remain so until landfall.

As the trough sets up during Idalia's final approach, upper diffluence combined with increasing OHC and SSTs will almost certainly allow for rapid intensification. 

(SST image courtesy of Brian McNoldy)

Once rapid intensification occurs, and it is explicitly forecast by the NHC, we don't know where it'll stop. Time will be a limiting factor, but it cuts both ways. On on hand, there may not be enough time for the very high ceiling for Idalia to be reached. On the other, the lack of time means that a structural change, such as an Eyewall Replacement Cycle (ERC) is less likely. 

There is also modest but meaningful divergence in track.

The consensus among most guidance is to bring this further north, while the European Model and stronger members of the EPS have a further east landfall. It's been talked about around here but we will need to watch for deviations closely, as there are almost always small changes that have a substantial impact on sensible weather.

To be clear--nobody living in the region should merely look at the center track. Heavy rain, storm surge, and strong to destructive winds will be possible far outside the center. Given the parallel run up the west coast of Florida however, where the center landfalls is obviously important for surge and strongest wind impacts. The 06z GFS ticked ever so slightly east relative to 00z. 

Watch the organizational trends, pace of intensification, and the wobbles relative to long term heading.

It should be an active day.

Nice post. Only two issues with my thoughts from late Sunday/early Monday is that I rushed the RI by about 12 hours by underplaying the initial shear a bit, and probably need to adjust west a tad.

[WxWatcher007]

Kind of a ho hum pass there. Good look structurally but FL and SFMR are not particularly strong. Peak SFMR just under 64kt. That said, that was N to S. I expect stronger findings on the eastern side. 

[Griizzcoat]

EYE getting going for sure

https://weather.cod.edu/satrad/?parms=meso-meso1-14-96-1-25-1&checked=map&colorbar=undefined

[StantonParkHoya]

This thing is booking it north

[WxWatcher007]

As expected. Dropsonde in the southern eyewall is quite a bit stronger than the northern side right now. 

Product: NOAA Temp Drop (Dropsonde) Message (UZNT13 KWBC)
Transmitted: 29th day of the month at 11:45Z
Agency: National Oceanic and Atmospheric Administration (NOAA)
Aircraft: Lockheed WP-3D Orion (Reg. Num. N43RF)
Storm Name: Idalia
Storm Number: 10 (flight in the North Atlantic basin)
Mission Number: 10
Observation Number: 06 ( See all messages of this type for this mission. )

Part A...
 

Date: Near the closest hour of 12Z on the 29th day of the month
Highest Mandatory Level For Which Wind Was Reported: 850mb
Coordinates: 23.5N 84.7W
Location: 151 statute miles (242 km) to the W (280°) from Havana, Cuba.
Marsden Square: 081 ( About )
 

Surface and Standard Isobaric Surfaces
Level	Geo. Height	Air Temp.	Dew Point	Wind Direction	Wind Speed
1000mb	-99m (-325 ft)	This level does not exist in this area of the storm above the surface level.
989mb (29.21 inHg)	Surface (Sea Level)	27.2°C (81.0°F)	25.8°C (78°F)	210° (from the SSW)	66 knots (76 mph)
925mb	591m (1,939 ft)	23.2°C (73.8°F)	22.4°C (72°F)	230° (from the SW)	75 knots (86 mph)
850mb	1,328m (4,357 ft)	20.4°C (68.7°F)	17.9°C (64°F)	255° (from the WSW)	76 knots (87 mph)
700mb	2,988m (9,803 ft)	Other data not available.

Information About Radiosonde:
- Launch Time: 11:30Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...
 

Dropsonde Location: Dropped in eyewall 180° (S) from the eye center.

Highest altitude where wind was reported:
- Location: 23.52N 84.74W
- Time: 11:30:11Z

Lowest altitude where wind was reported:
- Location: 23.55N 84.66W
- Time: 11:34:30Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 220° (from the SW)
- Wind Speed: 73 knots (84 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 250° (from the WSW)
- Wind Speed: 66 knots (76 mph)
- Depth of Sounding: From 707mb to 988mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:
- Lowest 150m: 154 gpm - 4 gpm (505 geo. feet - 13 geo. feet)
- Wind Direction: 215° (from the SW)
- Wind Speed: 71 knots (82 mph)

Sounding Software Version: AEV 30409
 

Part B: Data for Significant Levels...
 

Significant Temperature And Relative Humidity Levels
Level	Air Temperature	Dew Point
989mb (Surface)	27.2°C (81.0°F)	25.8°C (78°F)
935mb	23.6°C (74.5°F)	23.0°C (73°F)
850mb	20.4°C (68.7°F)	17.9°C (64°F)
700mb	13.0°C (55.4°F)	12.6°C (55°F)

 

Significant Wind Levels
Level	Wind Direction	Wind Speed
989mb (Surface)	210° (from the SSW)	66 knots (76 mph)
967mb	220° (from the SW)	76 knots (87 mph)
961mb	220° (from the SW)	72 knots (83 mph)
939mb	225° (from the SW)	76 knots (87 mph)
850mb	255° (from the WSW)	76 knots (87 mph)
707mb	275° (from the W)	56 knots (64 mph)