ATL: IRMA - Post-Tropical - Discussion

[PTPatrick]

She's not looking quite as nice and summetrical on satellite this morning. Wonder if she will back down a little bit. She does have a huge eye, which maybe I'm wrong but I'm not used to that in cat 5s.

[SkeetoBite]

stupid question, but I noticed a near full moon this morning, wondering if that could make flooding worse on the eastern coast?

Tides have to do with the Moon's location, not it's fullness. There are no stupid questions.

Tides are indeed affected by the moon's phase. Tides are most extreme (higher high tide, lower low tide) during the full moon and to a lesser extent during the new moon.

While that is technically true, it is easy to infer that the question related to a landfall at high tide and whether the fullness of the moon meant more flooding. Not to split hairs, but the differences would be minimal this time of year. The affect on inland flooding in relation to the Moon would be entirely based on the tide stage at the time of landfall.

[supercane4867]

EWRC clearly in progress while still not weakened much at the moment(150kt by recon).
The inner eyewall is quite stubborn so it may take some time to complete. Let hope this can weaken it further.

[NDG]

How much of a chance is a Myrtle Beach landfall? I am not able to get too much information on the area. Are we in the clear now?

If you are in the cone, your are NOT in the clear.

Not only that but Irma will be expanding as it reaches GA/SC line area, taking on a more subtropical structure so her strongest winds will be expanding to its east.

[terstorm1012]

We aren't in "perigean spring tide" time, I think that's usually toward the end of October after the equinox. Spring tides aren't named for the season, it's when the tidal range is at its maximum.

[hurricaneCW]

I think the scariest thing is that models show substantial deepening in the straits though that doesn't necessarily mean a wind increase as it it does an expansion in its size.

[NDG]

[GCANE]

RALEIGH, NC (WITN) - Governor Roy Cooper has declared a state of emergency ahead of Hurricane Irma possibly impacting the state.
The governor says the declaration, which is for the entire state, takes effect at 8:00 a.m. Thursday.

http://www.witn.com/content/news/Gov-Co ... 32563.html

[SEASON_CANCELED]

how can it continue to deepen?? What is it feeding on ??? I have never seen a category 5 sustain itself this long. This storm looks like it belongs on jupiters

[jasons2k]

Also, let's talk intensity. NHC, in its latest discussion, is mentioning some shear in 72 hours and generally thinking it as a high Cat 4 on its approach near Florida. Yet, some on this board seem to be calling for sub-900 mb and a 1935 Labor Day redo. Who's correct?

Both. There are subtleties there. The pro-mets I know thinking this will make a run at Sub-900 (and we're talking right at 899mb) in the straights, ALSO forecast some shear and a slight weakening just prior to landfall. In addition, there is not a perfect relationship to wind and pressure. Irma will be a very large hurricane with those pressures, so the winds won't wrap as tight as a storm like Wilma or Patricia.

Like I said last night, we'll be splitting hairs over pressures and wind speeds on final approach. The main message is SE FL needs to prepare for a worst case, and just leave if you can.

[GCANE]

 https://twitter.com/HappeningsRadio/status/905774874102255617

[GCANE]

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 7th day of the month at 12:51Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5305
Storm Number & Year: 11 in 2017
Storm Name: Irma (flight in the North Atlantic basin)
Mission Number: 17
Observation Number: 11 ( See all messages of this type for this mission. )
A. Time of Center Fix: 7th day of the month at 12:28:10Z
B. Center Fix Coordinates: 20°09'N 69°04'W (20.15N 69.0667W)
B. Center Fix Location: 128 statute miles (206 km) to the NNE (26°) from Santo Domingo, Dominican Republic.
C. Minimum Height at Standard Level: 2,402m (7,881ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 140kts (~ 161.1mph)
E. Location of the Estimated Maximum Surface Wind Inbound: 10 nautical miles (12 statute miles) to the W (261°) of center fix
F. Maximum Flight Level Wind Inbound: From 358° at 130kts (From the N at ~ 149.6mph)
G. Location of Maximum Flight Level Wind Inbound: 11 nautical miles (13 statute miles) to the W (260°) of center fix
H. Minimum Sea Level Pressure: 921mb (27.20 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 12°C (54°F) at a pressure alt. of 3,047m (9,997ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 3,053m (10,016ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Closed
M. Eye Shape & Diameter: Circular with a diameter of 24 nautical miles (28 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile

Remarks Section:
Maximum Flight Level Wind: 152kts (~ 174.9mph) which was observed 3 nautical miles to the NE (35°) from the flight level center at 11:18:00Z
Maximum Flight Level Wind Outbound: 150kts (~ 172.6mph) which was observed 17 nautical miles (20 statute miles) to the NE (55°) from the flight level center at 12:33:00Z
Maximum Flight Level Temp: 18°C (64°F) which was observed 8 nautical miles to the W (265°) from the flight level center

[GCANE]

[tolakram]

Another question. I'm aware I'm trying to grasp on to anything that might lessen the severity of Irma's impact on S. Florida, but hey, that's understandable, right, and beyond that, I do want to fully understand what's going on.

Take a look at the current extrapolated motion. It would cut just below Andros and into the middle-upper Keys, say Islamorada/Tavernier area. The extrapolated is north of NHC's current forecast track. Are we for sure expecting Irma to take more of a due westerly course soon, so it gets closer in line with the NHC track for its sickening approach on S. Florida? Otherwise, it would look like the current HWRF and/or GFS track is kind of on point for now, no?

Sorry, but with all due respect I don't understand and it's not understandable. It's a fools game to watch the models at this point. I can't say it any stronger than that without violating s2k rules. If you are really insistent on following models you should have, at your fingertips, the current model error report, the model bias report, and the NHC verification statistics which show them out performing every individual model except for the euro. If you don't know or don't have these ...

Over in the model thread we enjoy following models, trying to guess where this is going and looking at some of the tools the NHC uses. Unfortunately there seems to be some who believe they can out forecast the NHC. Fools game. Sorry to call you out but time is running short and this needed to be said.

[BlueWater36]

My wife, family, and a few friends will be hunkering down in our home in Port Saint Lucie.

We live in a frame house 11 miles from the coast. Solid roof with straps. Stucco walls and soffits (stucco goes under the roof line.) No trees or telephone poles within falling distance. Hurricane shutters up. Gable ends boarded up. Impact back door, hurricane rated garage door, shutters for the front door. We're as best prepared as we can be. Hoping she weakens a bit by the time she gets up here. Wish us luck.

[Blown Away]

Very little wobbling today, Irma steady on track hitting NHC forecast points... About to cross 70W, closing in...

[terstorm1012]

Most of my South Dade family has chosen to stay put. I really wish they hadn't. I realize they're all old-school Floridians and Conchs and this is hardly their first time at the rodeo but, the forecast just does not look good.

[tolakram]

My wife, family, and a few friends will be hunkering down in our home in Port Saint Lucie.

We live in a frame house 11 miles from the coast. Solid roof with straps. Stucco walls and soffits (stucco goes under the roof line.) No trees or telephone poles within falling distance. Hurricane shutters up. Gable ends boarded up. Impact back door, hurricane rated garage door, shutters for the front door. We're as best prepared as we can be. Hoping she weakens a bit by the time she gets up here. Wish us luck.

That's all good but do you have at least 10 days of supplies? Filling bathtubs with water, etc? A lot of folks were gob smacked when Wilma moved through and no one could get supplies into some areas. Good luck.

[mrbagyo]

I think the scariest thing is that models show substantial deepening in the straits though that doesn't necessarily mean a wind increase as it it does an expansion in its size.

superimposed image of Irma, past and present.

I wonder how large she'll gonna get at the Bahamas, a possible interaction with the trough will surely make her appear even larger.

[dukeblue219]

Also, let's talk intensity. NHC, in its latest discussion, is mentioning some shear in 72 hours and generally thinking it as a high Cat 4 on its approach near Florida. Yet, some on this board seem to be calling for sub-900 mb and a 1935 Labor Day redo. Who's correct?

Both. There are subtleties there. The pro-mets I know thinking this will make a run at Sub-900 (and we're talking right at 899mb) in the straights, ALSO forecast some shear and a slight weakening just prior to landfall. In addition, there is not a perfect relationship to wind and pressure. Irma will be a very large hurricane with those pressures, so the winds won't wrap as tight as a storm like Wilma or Patricia.

Like I said last night, we'll be splitting hairs over pressures and wind speeds on final approach. The main message is SE FL needs to prepare for a worst case, and just leave if you can.

I think it's very plausible (but I won't give odds) that this storm's pressure will slowly decrease over the next 48 hours while the winds slightly decrease as well, and in exchange the radius increases substantially. There's no doubt conditions support a powerful, deep low pressure system while we also know there are fundamental limits on core wind speed and plenty of complex core dynamics that we don't seem to fully understand. Either way, it's gonna be a big one and nobody in the Florida Peninsula or the GA/SC/NC coast should be claiming they're in the clear until the storm is passing them by. (Not a Met)