Hurricane Idalia

[GaWx]

1 hour ago, 40/70 Benchmark said:

Here is my first stab at it.

https://easternmassweather.blogspot.com/2023/08/newly-formed-idalia-likely-to-strike.html?m=1

 Even though Cedar Key is 90 miles from Tampa, a strong cat 3 landfall like your first stab shows would I believe put Tampa Bay at risk for a 7-8 foot storm surge based on analogs. That would make it the highest surge there since 1921. Thus, that might seem overdone. But keep in mind that in 1950 on Sep 5, H Easy initially hit Cedar Key moving NE where it had a 958 mb/120 mph/cat 3 landfall. There was a 6.5 foot surge at Tampa Bay. Adding some for your slightly stronger 125 mph as well as you having it way up at 150 mph 24 hours earlier tells me that there'd probably be a risk of a bit higher than this analog's 6.5 foot surge.

 What's even more scary is that 2020's Eta was only a 50 mph TS when it, too, landfalled at Cedar Key (moving NNE like Idalia is projected to do) and it was able to produce a 4.2 foot surge at Tampa Bay! If a 50 mph TS centered up at Cedar Key can produce a 4.2 foot surge, I'd think that a 125 mph H centered in the same area could conceivably produce near double that. Then again, there may have been some highly unusual circumstances with Eta that won't be present with Idalia.

[CheeselandSkies]

0Z HAFS-B gets it down to 929 MB (strongest non-fantasy range hurricane model output I've seen thus far) at FH057, but brings it back up a bit before landfall. All the hurricane models (and have for several runs) agree on a solid major hurricane, potentially a high-end (125kt+) one.

[40/70 Benchmark]

18 minutes ago, GaWx said:

 Even though Cedar Key is 90 miles from Tampa, a strong cat 3 landfall like your first stab shows would I believe put Tampa Bay at risk for a 7-8 foot storm surge based on analogs. That would make it the highest surge there since 1921. Thus, that might seem overdone. But keep in mind that in 1950 on Sep 5, H Easy initially hit Cedar Key moving NE where it had a 958 mb/120 mph/cat 3 landfall. There was a 6.5 foot surge at Tampa Bay. Adding some for your slightly stronger 125 mph as well as you having it way up at 150 mph 24 hours earlier tells me that there'd probably be a risk of a bit higher than this analog's 6.5 foot surge.

 What's even more scary is that 2020's Eta was only a 50 mph TS when it, too, landfalled at Cedar Key (moving NNE like Idalia is projected to do) and it was able to produce a 4.2 foot surge at Tampa Bay! If a 50 mph TS centered up at Cedar Key can produce a 4.2 foot surge, I'd think that a 125 mph H centered in the same area could conceivably produce near double that. Then again, there may have been some highly unusual circumstances with Eta that won't be present with Idalia.

One saving grace, Larry is that it probably won't have much time to expand.

[LakeEffectKing]

Seen this dog and pony show before....too many parameters trending positive for RI in 18-36 hrs.

Idalia should easily be a major by tomorrow, and may very well be CAT 4 by 06z Wed.

[WxSynopsisDavid]

1 minute ago, LakeEffectKing said:

Seen this dog and pony show before....too many parameters trending positive for RI in 18-36 hrs.

Idalia should easily be a major by tomorrow, and may very well be CAT 4 by 06z Wed.

Once that vertical column stacks, it’s game on. We are close now to that happening.

[LakeEffectKing]

2 minutes ago, WxSynopsisDavid said:

Once that vertical column stacks, it’s game on. We are close now to that happening.

Probably in the next 18-24 hrs. Takes a bit of time to get all levels aligned AND to clear out the center....then boom!

[WxSynopsisDavid]

4 minutes ago, LakeEffectKing said:

Probably in the next 18-24 hrs. Takes a bit of time to get all levels aligned AND to clear out the center....then boom!

I’ll take that bet and say 12hrs tops. So far what Idalia was able to pull off with 30kts of shear was impressive. 
 

Also….Idalia is now beginning to interact with a noticeable warm eddy so I think because of this the process happens much sooner.

[Rtd208]

I know everyone is concentrating on Florida but eventually there are going to be some impacts in GA, SC and NC as well.

[WxSynopsisDavid]

3 minutes ago, Rtd208 said:

I know everyone is concentrating on Florida but eventually there are going to be some impacts in GA, SC and NC as well.

No one has forgotten but there are still uncertainties on track and intensity. Unfortunately we won’t really know for sure what those impacts will be until Tuesday. 

[WxWatcher007]

3 hours ago, 40/70 Benchmark said:

Here is my first stab at it.

https://easternmassweather.blogspot.com/2023/08/newly-formed-idalia-likely-to-strike.html?m=1

Always appreciate seeing your thoughts. Nice write up. 

[SnoSki14]

1 hour ago, LakeEffectKing said:

Seen this dog and pony show before....too many parameters trending positive for RI in 18-36 hrs.

Idalia should easily be a major by tomorrow, and may very well be CAT 4 by 06z Wed.

I think there are much more negative factors than with previous storms. A lot of dry air and shear present and it won't ever get fully favorable.

Plus time will be a factor. I don't think warm SSTs alone will do it.

I don't expect more than a Cat 2 at landfall.

[WxSynopsisDavid]

1 minute ago, SnoSki14 said:

I think there are much more negative factors than with previous storms. A lot of dry air and shear present and it won't ever get fully favorable.

Plus time will be a factor. I don't think warm SSTs alone will do it.

I don't expect more than a Cat 2 at landfall.

Shear has actually rapidly decreased the last 3 hours. Shear values north of Idalia went from 40kts to 25kts now. Dry air has abated the core and there’s little dry air to the north. This is a similar environment that Michael had in all honesty. One could argue a better environment ahead than what Michael had.

[WxWatcher007]

Morning, everyone. There are going to be numerous missions at high and low altitude through landfall for Idalia now. The first morning low altitude flight is descending now. This is mission 5. An additional flight, mission 6, is starting to descend as well. 

[nycwinter]

21 minutes ago, SnoSki14 said:

I think there are much more negative factors than with previous storms. A lot of dry air and shear present and it won't ever get fully favorable.

Plus time will be a factor. I don't think warm SSTs alone will do it.

I don't expect more than a Cat 2 at landfall.

Over the Gulf of Mexico, the environment is forecast to become 
conducive for significant strengthening of Idalia due to a new 
trough dropping south over the western Gulf of Mexico as a 
upper-level ridge builds near the cyclone.  Additionally, Idalia 
will be moving over waters near 31C, and some of the guidance is 
even indicating favorable jet dynamics on Wednesday with Idalia in 
the right-rear quadrant of the jet over the southeastern United 
States.  The bottom line is that rapid intensification is becoming 
increasingly likely before landfall, and the NHC forecast now 
explicitly indicates it between 24-48 h in the forecast.  This is 
consistent with almost all of the regional hurricane models and the 
SHIPS rapid intensification indices, which are 5-10 times the 
climatological mean.  The new prediction shows a 100-kt hurricane 
over the eastern Gulf of Mexico at 48 hours, but Idalia should keep 
strengthening up to landfall along the Gulf coast of Florida.  
Interests within the storm surge and hurricane watch areas are urged 
to prepare for possible significant impacts and monitor future 
updates to the forecast for this increasingly dangerous situation.

[WxWatcher007]

Mission 5 approaching the center to do a NW to SE pass. Getting a better sense of the wind field in each quadrant, as well as if there's a low level attempt at developing an eyewall is what I'm paying close attention to. It looks like it's trying again on radar, but recon will confirm. Idalia is clearly getting closer, however, and we're starting to see--for now at least--some convection to the north trying to wrap around. 

[WxWatcher007]

Mission 5 first pass produced an extrapolated pressure of 990.4mb. Peak FL wind of 50kt and unflagged peak SFMR of 55kt. 

Edit: basically confirms 5am intensity. 

[WxWatcher007]

Center dropsonde

 

Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)
Transmitted: 28th day of the month at 11:25Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF99-5309
Storm Name: Idalia
Storm Number: 10 (flight in the North Atlantic basin)
Mission Number: 5
Observation Number: 06 ( See all messages of this type for this mission. )

Part A...
 

Date: Near the closest hour of 11Z on the 28th day of the month
Highest Mandatory Level For Which Wind Was Reported: 850mb
Coordinates: 20.6N 85.1W
Location: 120 statute miles (193 km) to the ESE (109°) from Cancún, Quintana Roo, Mexico.
Marsden Square: 081 ( About )
 

Surface and Standard Isobaric Surfaces
Level	Geo. Height	Air Temp.	Dew Point	Wind Direction	Wind Speed
1000mb	-93m (-305 ft)	This level does not exist in this area of the storm above the surface level.
990mb (29.24 inHg)	Surface (Sea Level)	27.8°C (82.0°F)	25.7°C (78°F)	125° (from the SE)	12 knots (14 mph)
925mb	599m (1,965 ft)	24.4°C (75.9°F)	22.3°C (72°F)	150° (from the SSE)	9 knots (10 mph)
850mb	1,340m (4,396 ft)	21.2°C (70.2°F)	19.8°C (68°F)	150° (from the SSE)	8 knots (9 mph)

Information About Radiosonde:
- Launch Time: 11:18Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...
 

Dropsonde Location: Dropped in center.

Highest altitude where wind was reported:
- Location: 20.61N 85.14W
- Time: 11:18:37Z

Lowest altitude where wind was reported:
- Location: 20.61N 85.14W
- Time: 11:20:49Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 130° (from the SE)
- Wind Speed: 11 knots (13 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 140° (from the SE)
- Wind Speed: 9 knots (10 mph)
- Depth of Sounding: From 843mb to 989mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:
- Lowest 150m: 155 gpm - 5 gpm (509 geo. feet - 16 geo. feet)
- Wind Direction: 125° (from the SE)
- Wind Speed: 13 knots (15 mph)

Sounding Software Version: AEV 30407
 

Part B: Data for Significant Levels...
 

Significant Temperature And Relative Humidity Levels
Level	Air Temperature	Dew Point
990mb (Surface)	27.8°C (82.0°F)	25.7°C (78°F)
850mb	21.2°C (70.2°F)	19.8°C (68°F)

 

Significant Wind Levels
Level	Wind Direction	Wind Speed
990mb (Surface)	125° (from the SE)	12 knots (14 mph)
957mb	125° (from the SE)	10 knots (12 mph)
904mb	155° (from the SSE)	10 knots (12 mph)
854mb	140° (from the SE)	8 knots (9 mph)
843mb	165° (from the SSE)	8 knots (9 mph)

[beanskip]

Seems to be no mention of the decided westward trends in some of the models (in addition to the pronounced slowing trend). 0z Euro went slightly west. The HMON went more than a full degree of longtitude west. CMC -- west. GFS held serve with its western track.

 

[WxWatcher007]

Mission 6 is doing a pass from N to S and has an extrapolated pressure so far of 985.1mb. The caveat here is that this is being extrapolated from an altitude of ~12,300ft. SFMR peak winds consistent with Mission 5 so far. 

[WxWatcher007]

First VDM from mission 5. No eye observed at this time. 

 

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 11:59Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF99-5309
Storm Name: Idalia
Storm Number & Year: 10 in 2023 (flight in the North Atlantic basin)
Mission Number: 5
Observation Number: 05 ( See all messages of this type for this mission. )

A. Time of Center Fix: 28th day of the month at 11:18:10Z
B. Center Fix Coordinates: 20.61N 85.17W
B. Center Fix Location: 115 statute miles (185 km) to the ESE (109°) from Cancún, Quintana Roo, Mexico.
C. Minimum Height at Standard Level: 1,351m (4,432ft) at 850mb
D. Minimum Sea Level Pressure: 990mb (29.24 inHg)
E. Dropsonde Surface Wind at Center: From 125° at 12kts (From the SE at 14mph)
F. Eye Character: Not Available
G. Eye Shape: Not Available
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 35kts (40.3mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 23 nautical miles (26 statute miles) to the WNW (300°) of center fix at 11:11:00Z
J. Maximum Flight Level Wind Inbound: From 24° at 37kts (From the NNE at 42.6mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 17 nautical miles (20 statute miles) to the WNW (294°) of center fix at 11:13:00Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 57kts (65.6mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 26 nautical miles (30 statute miles) to the SE (128°) of center fix at 11:27:00Z
N. Maximum Flight Level Wind Outbound: From 191° at 56kts (From between the S and SSW at 64.4mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 59 nautical miles (68 statute miles) to the SE (132°) of center fix at 11:39:00Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 1,530m (5,020ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 1,530m (5,020ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 16°C (61°F)
R. Sea Surface Temp (collected at same location as temp inside eye): Not Available
S. Fix Determined By: Penetration, Wind and Pressure
S. Fix Level: 850mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 3 nautical miles

Remarks Section:
 

Maximum Flight Level Wind: 56kts (~ 64.4mph) which was observed 59 nautical miles (68 statute miles) to the SE (132°) from the flight level center at 11:39:00Z
Maximum Flight Level Temp: 23°C (73°F) which was observed 11 nautical miles (13 statute miles) to the WNW (289°) from the flight level center

[WxWatcher007]

Mission 6 extrapolated down to 983.9mb but again, the caveat is that this was extrapolated at ~12,000ft. Nothing earth shattering about FL winds or SFMR so this is probably too low. Dropsonde would confirm. 

Stepping away for a bit unless there's something really interesting.  

[Hotair]

Satellite is suggestive of Idalia forming an eye .  

[CoastalWx]

Still has that elongated area of convection from SSW-NNE.  It has some work to do still as far as organization.

[Hotair]

NOAA3 

 

 

[WxSynopsisDavid]

29 minutes ago, Hotair said:

Satellite is suggestive of Idalia forming an eye .  

Negative. The cloud tops are casting a shadow that is given the appearance of an eye. No eye is developing yet, according to recon.

[Boston Bulldog]

Not quite sure where the shear is decreasing narrative has come from. Currently the storm is dealing with moderate shear which is tilting the core despite the strong convection. We've observed several wrap up attempts that have failed so far, which is likely due to this ~15-20kts of shear, and some dry air still showing up around 800 hPa on dropsonde data.

There has been no observed decrease in vertical wind shear over the past 24 hours ahead of the system or over the system.

Idalia will remain under similar conditions as it lifts into the gulf. We may see a period of little to no shear as the flow switches direction while the tough approaches (likely when we will see the strongest chance for RI). From there the trough will begin to increase vertical shear again, this time southerly. However, favorable synoptic interaction with the equatorward entrance region of the jet streak that will be traversing the eastern US at this time will likely offset the negative effects of this southerly shear as Idalia approaches landfall thanks to diffluence.

Just speculating here, but I wonder if this southerly shear and dry air behind the system at landfall would eat away at the back eyewall upon approach, as we have seen with so many other gulf "halficane" landfalls in recent years

EDIT: Fixed poleward to equatorward

[beanskip]

2 minutes ago, Boston Bulldog said:

Not quite sure where the shear is decreasing narrative has come from. Currently the storm is dealing with moderate shear which is tilting the core despite the strong convection. We've observed several wrap up attempts that have failed so far, which is likely due to this ~15-20kts of shear, and some dry air still showing up around 800 hPa on dropsonde data.

http://tropic.ssec.wisc.edu/real-time/atlantic/winds/wg8shr.GIF

There has been no observed decrease in vertical wind shear over the past 24 hours ahead of the system or over the system.

http://tropic.ssec.wisc.edu/real-time/atlantic/winds/wg8sht.GIF

Idalia will remain under similar conditions as it lifts into the gulf. We may see a brief period of little to no shear as the flow switches direction while the tough approaches (likely when we will see the strongest chance for RI). From there the trough will begin to increase vertical shear again, this time southerly. However, favorable synoptic interaction with the poleward entrance region of the jet streak that will be traversing the eastern US at this time will likely offset the negative effects of this southerly shear as Idalia approaches landfall thanks to diffluence.

Just speculating here, but I wonder if this southerly shear and dry air behind the system at landfall would eat away at the back eyewall upon approach, as we have seen with so many other gulf "halficane" landfalls in recent years

This is excellent. To wit, it does not appear the pressure is dropping per latest recon pass.

 

[Hotair]

TV reminding folks how far Ian track was from actual LF 72 hours out. I do believe the steering patterns are a little better behaved this time given the multi model consensus, but no one inside the cone should let their guard down  

 

 

[eyewall]

5 minutes ago, Hotair said:

TV reminding folks how far Ian track was from actual LF 72 hours out. I do believe the steering patterns are a little better behaved this time given the multi model consensus, but no one inside the cone should let their guard down  

 

 

Yeah Charlie ended up farther down the coast too like that.

[beanskip]

1 minute ago, eyewall said:

Yeah Charlie ended up farther down the coast too like that.

Is there history on the direction of this miss. These two examples are both to the right -- is that a known bias or just a coincidence for these two?