Major Hurricane Irma

[Casualbrain]

16 minutes ago, bdgwx said:

From: http://www.atmos.albany.edu/facstaff/tang/tcguidance/

UKMET has been doing well too, but the NHC is beating it at 96 hours. We should have the 120 hour verifications tomorrow evening. You can also see that NHC has positive skill compared to the TVCN consensus at least at 72 and 96 hours. That doesn't always happen.

Some good stats on model performance over at http://rammb.cira.colostate.edu/products/tc_realtime/storm.asp?storm_identifier=AL112017 as well

EDIT - meant this page - sorry http://rammb.cira.colostate.edu/products/tc_realtime/storm_model_data.asp?storm_identifier=AL112017

 

[RU848789]

12 minutes ago, bdgwx said:

From: http://www.atmos.albany.edu/facstaff/tang/tcguidance/

UKMET has been doing well too, but the NHC is beating it at 96 hours. We should have the 120 hour verifications tomorrow evening. You can also see that NHC has positive skill compared to the TVCN consensus at least at 72 and 96 hours. That doesn't always happen.

 

Thanks!  That's an awesome graphic.  Euro truly is kicking ass.  

[beanskip]

54 minutes ago, kvegas-wx said:

Nice dose of reality from DT.  Everyone here hoping for a LF (God only knows why) should read it and understand the biases of the GFS and the historical preference granted to the Euro for correctly sniffing out some unusual storms.  OTS is ABSOLUTELY still on the board here!

Whatever. Thursday 12z Euro had Irma over Key West. It has been all over the place which works for DT because he can claim it's right no matter what happens.

 

[MattPetrulli]

The Euro sucking in this thread needs to stop. While in the short term it has been doing well, we also have to remember it has been inconsistent with model runs. 

[Coach McGuirk]

2 minutes ago, MattPetrulli said:

The Euro sucking in this thread needs to stop. While in the short term it has been doing well, we also have to remember it has been inconsistent with model runs. 

Who's saying that?  The Euro is usually the best when it comes to Tropics.  It certainly may go out to sea, we don't don't. 

[MattPetrulli]

Just now, Coach McGuirk said:

Who's saying that?  The Euro is usually the best when it comes to Tropics.  It certainly may go out to sea, we don't don't. 

It may certainly go out to sea, but we have to remember it has been inconsistent the last few model runs.

[MattPetrulli]

Irma is trying to clear a ragged eye amid a ragged appearance too. 

[TPAwx]

1 minute ago, MattPetrulli said:

It may certainly go out to sea, but we have to remember it has been inconsistent the last few model runs.

The Euro op or any op model run showing different solutions 120+ hours out is not inconsistency, it's just assimilating evolving data and producing different variations on the larger synoptic features that translate to the track of a specific low pressure system.  It would be unusual to see the same op solution this far out, run after run, with minimal deviation.  We're dealing with the 180 hour timeframe here.

[Casualbrain]

GOES 16 slider really shows off this beautiful beast Irma

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=full_disk&x=15620&y=6752&z=2&im=60&ts=1&st=0&et=0&speed=160&motion=loop&map=1&lat=1&p[0]=16&opacity[0]=1&hidden[0]=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&s=rammb-slider

[Coach McGuirk]

Just now, Casualbrain said:

GOES 16 slider really shows off this beautiful beast Irma

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=full_disk&x=15620&y=6752&z=2&im=60&ts=1&st=0&et=0&speed=160&motion=loop&map=1&lat=1&p[0]=16&opacity[0]=1&hidden[0]=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&s=rammb-slider

Meh, it's no beast at the moment.  115 MPH cane.

[Jackstraw]

Recon dropped some AXBT's in front of the storm.  As the NHC mentioned it's heading into progressively warmer SST's. The 26 degree isotherm goes down to about 240 feet which is around the depth they were finding in the western gulf with Harvey.  I find that interesting as I would think that would not be as deep in the Atlantic as it is in the gulf.  

[MattPetrulli]

Just now, TPAwx said:

The Euro op or any op model run showing different solutions 120+ hours out is not inconsistency, it's just assimilating evolving data and producing different variations on the larger synoptic features that translate to the track of a specific low pressure system.  It would be unusual to see the same op solution this far out, run after run, with minimal deviation.  We're dealing with the 180 hour timeframe here.

That's literally the definition of inconsistency. No model will be locked in 180 hours out +. However, some here are acting like we should put a little more thought into the Euro than some of the more consistent models so far. Yes I do know the Euro is the better model, but GFS has been fairly consistent as of late. At this point, it should be equally balanced track wise between GFS and euro so far. Equal amount of thought should be put into the tracks for both runs. 

[Torchageddon]

After having a good laugh with the 18z HMON run, I wondered why it uncoupled from the ocean and what exactly that means. If its a serious model and not in experimental mode what's the deal? You could tell it was glitched just by the equal drops of pressure (4-5 mb) in 3 hr increments. Other runs by it and the HWRF show it going sub-890 mb for more than a few runs...were those all bugged too?
 

[SnowLover22]

You can see an eye  starting to clear out on sat.

[Jackstraw]

7 minutes ago, Torchageddon said:

After having a good laugh with the 18z HMON run, I wondered why it uncoupled from the ocean and what exactly that means. If its a serious model and not in experimental mode what's the deal? You could tell it was glitched just by the equal drops of pressure (4-5 mb) in 3 hr increments. Other runs by it and the HWRF show it going sub-890 mb for more than a few runs...were those all bugged too?
 

If it was supposed to replace the crack model then the user went to jail but the dealer is still in town 

As to Irma, somethings been messing with the inner core and I think it might be the ridge pushing it SW.  Last night shortwave IR showed the entire north side of the storm flatten like it was getting stepped on, for about 6 hours.  The northern eye wall was disrupted earlier today.  It's inner core has just been behaving erratically.  I think if you read between the lines in some of the NHC's past discussions  it has raised an eyebrow there too.  Just an observation.

[yoda]

6 minutes ago, Jackstraw said:

If it was supposed to replace the crack model then the user went to jail but the dealer is still in town 

As to Irma, somethings been messing with the inner core and I think it might be the ridge pushing it SW.  Last night shortwave IR showed the entire north side of the storm flatten like it was getting stepped on, for about 6 hours.  The northern eye wall was disrupted earlier today.  It's inner core has just been behaving erratically.  I think if you read between the lines in some of the NHC's past discussions  it has raised an eyebrow there too.  Just an observation.

From the 5pm disco:

There is evidence
of some northerly flow beneath the cirrus outflow, which may be
disrupting the inner core and preventing Irma from strengthening.

[yoda]

BULLETIN
Hurricane Irma Advisory Number  19
NWS National Hurricane Center Miami FL       AL112017
1100 PM AST Sun Sep 03 2017

...MAJOR HURRICANE IRMA EXPECTED TO BE NEAR THE NORTHERN LEEWARD
ISLANDS TUESDAY NIGHT...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.2N 51.0W
ABOUT 710 MI...1145 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WSW OR 255 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...961 MB...28.38 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Watch is in effect for...
* Antigua, Barbuda, Anguilla, Montserrat, St. Kitts, and Nevis
* Saba, St. Eustatius, and Sint Maarten
* Saint Martin and Saint Barthelemy

Interests in the remainder of the Leeward Islands, the British and
U.S. Virgin Islands, and Puerto Rico should monitor the progress of
Irma.  Additional Hurricane and Tropical Storm Watches may be
required for portions of this area on Monday.

[Santa Claus]

17 minutes ago, Philadelphia Snow said:

You can see an eye  starting to clear out on sat.

Pretty pronounced now, wonder if we'll start to see some of this strengthening we've been waiting for.  Convection is still sort of disorganized but lets see those thunderstorms in the NE quad start to spin a bit.

I'm on the edge of my seat waiting to see how these intensity forecasts shake out.  I've never followed a storm where so many models had such ridiculous central pressure predictions.  It would be a shock to see anything remotely close to that verify.

Here's a question, if I set the over/under of minimum pressure at 900 mb, who here would take the under?  I would not.

[yoda]

Hurricane Irma Discussion Number  19
NWS National Hurricane Center Miami FL       AL112017
1100 PM AST Sun Sep 03 2017

Observations from a NOAA Hurricane Hunter aircraft indicated a 25 n
mi diameter eye and maximum SFMR-observed surface winds close to
100 kt.  That value will be retained for the official intensity.
Central core convection is beginning to become a little better
organized on satellite imagery and the upper-level outflow is
well defined.  Given the favorable environment, Irma is likely to
strengthen some more over the next day or two.  The official
intensity forecast follows the model consensus.

Based on center fixes from the Hurricane Hunters, Irma has been
moving a little south of west or around 255/12 kt.  A strong high
pressure ridge over the central Atlantic should steer Irma on a
west-southward to westward course over the next couple of days.
After that time, a turn toward the west-northwest is likely while
Irma nears the western portion of the ridge.  There continues to be
a rather small cross-track spread in most of the track guidance
models, but there are some speed differences.  The official track
forecast is roughly in the middle of the guidance and is just
slightly south of the previous NHC prediction.

Users are reminded to not focus on the exact forecast track since
strong winds and heavy rainfall extend well away from the center.

KEY MESSAGES:
1. Irma is expected to affect the northeastern Leeward Islands by
the middle of this week as a major hurricane, accompanied by
dangerous wind, storm surge, and rainfall impacts, along with rough
surf and rip currents.  Hurricane watches have been issued for
portions of the Leeward Islands and additional hurricane or tropical
storm watches or warnings may be required on Monday.  Residents in
these areas should monitor the progress of Irma and listen to advice
given by officials.

2. Irma is expected to remain a dangerous major hurricane through
the upcoming week and could directly affect the British and U.S.
Virgin Islands, Puerto Rico, Hispaniola, the Turks and Caicos, and
the Bahamas.  Residents in all of these areas should monitor the
progress of Irma and listen to advice given by officials.  Tropical
storm or hurricane watches could be issued for the British and U.S.
Virgin Islands and Puerto Rico on Monday.

3. It is too early to determine what direct impacts Irma might have
on the continental United States.  Regardless, everyone in
hurricane-prone areas should ensure that they have their hurricane
plan in place, as we are now near the peak of the season.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 17.2N  51.0W  100 KT 115 MPH
 12H  04/1200Z 16.7N  52.6W  105 KT 120 MPH
 24H  05/0000Z 16.5N  54.8W  110 KT 125 MPH
 36H  05/1200Z 16.8N  57.1W  115 KT 130 MPH
 48H  06/0000Z 17.4N  59.6W  120 KT 140 MPH
 72H  07/0000Z 19.3N  65.0W  120 KT 140 MPH
 96H  08/0000Z 21.2N  70.2W  115 KT 130 MPH
120H  09/0000Z 22.8N  74.5W  115 KT 130 MPH

$$
Forecaster Pasch

[Jim Marusak]

8 minutes ago, Will - Rutgers said:

Pretty pronounced now, wonder if we'll start to see some of this strengthening we've been waiting for.  Convection is still sort of disorganized but lets see those thunderstorms in the NE quad start to spin a bit.

I'm on the edge of my seat waiting to see how these intensity forecasts shake out.  I've never followed a storm where so many models had such ridiculous central pressure predictions.  It would be a shock to see anything remotely close to that verify.

Here's a question, if I set the over/under of minimum pressure at 900 mb, who here would take the under?  I would not.

900? heck no, way too low for an o/u bet. now if you set that o/u line at say 930 or 935 for an opening line, I think you might get some action on both sides.

[Isotherm]

The key determinants of cyclone trajectory are the mid latitude synoptic scale features predominantly in the D6+ period, a time frame in which all model verification scores, including the ECMWF, decrease substantially. So again, I think it's important to note that the ECMWF too will almost certainly change from its current depiction. Whether that alteration will yield a lesser or greater threat to the coast is indeterminate, but it seems that there may be an implicit intimation by some that the Euro's current output is much more likely to verify due to its short-medium range skill in prognosticating Irma's path. Important to remember that the synoptic evolution at this lead time is quite capricious and will invariably be different again at 00z.

[Santa Claus]

Just now, Jim Marusak said:

900? heck no, way too low for an o/u bet. now if you set that o/u line at say 930 or 935 for an opening line, I think you might get some action on both sides.

That's fine, I'm just reacting to these model runs.  Like I said I haven't seen anything like this in numerical weather prediction.

You're the met, any input as to why there's been such consistently insane runs here?

[Jim Marusak]

from what everyone is saying in here, we have a model issue. basically, the heat balance is off as it's going off of statistical normal ocean water temperatures, not what actually is going on. it's de-coupling the ocean. and when you de-couple the ocean like that, things tend to go towards the extremes more than what might be more typical as it doesn't take into potential account things like upwelling, anomalies in temperatures, or other issues.

[beanskip]

6 minutes ago, Jim Marusak said:

from what everyone is saying in here, we have a model issue. basically, the heat balance is off as it's going off of statistical normal ocean water temperatures, not what actually is going on. it's de-coupling the ocean. and when you de-couple the ocean like that, things tend to go towards the extremes more than what might be more typical as it doesn't take into potential account things like upwelling, anomalies in temperatures, or other issues.

Which leads me to ask, what impact, if any, would there be on a track from a model which is overmodeling the intensity of the storm?

[Santa Claus]

1 minute ago, Jim Marusak said:

from what everyone is saying in here, we have a model issue. basically, the heat balance is off as it's going off of statistical normal ocean water temperatures, not what actually is going on. it's de-coupling the ocean. and when you de-couple the ocean like that, things tend to go towards the extremes more than what might be more typical as it doesn't take into potential account things like upwelling, anomalies in temperatures, or other issues.

Don't we have slightly above average SST anomalies in the storm's path?

I'm not sure how anyone could use a model for a tropical system that isn't taking into account ocean conditions (but I guess that's the point and that's why the intensity forecasts are being discounted).  To my point, I've looked at the GFS in other tropical situations before and haven't seen these kind of predictions.

Not trying to argue btw... novice trying to make sense of things.

[SN_Lover]

Never knew or noticed they did buoy drops. Anyways, "shocker" bathtub water ahead of the Irma. 

 

Quote

Product: Bathythermal Data (SOFX01 KWBC)
Date Profile Data was Processed: September 4th, 2017 at 0:47:14Z
Agency: National Oceanic and Atmospheric Administration (NOAA)
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Name: None 
AXBT Buoy Drop (Airborne eXpendable Bathythermograph)

Profile Date: September 4th, 2017
Profile Time: 0:39:54Z

Profile Coordinates: 17.523N 53.476W 
Profile Location: 510 statute miles (820 km) to the NE (53°) from Bridgetown, Barbados.

AXBT Channel: 16

Sea Surface Temperature: 29.00°C (84.2°F)
Depth of 26°C Isotherm: 67.5 m (221 ft)
Deepest Depth of AXBT: 403.5 m (1,324 ft)

 

[Jim Marusak]

1 minute ago, beanskip said:

Which leads me to ask, what impact, if any, would there be on a track from a model which is overmodeling the intensity of the storm?

I'm not a modeling specialist, i'm more a forecaster, so please take this with a grain of salt. it can have some effect on the synoptic scale. but more than anything else, it has effects on things like strength and precipitation, things most affected by latent heat and heat balance (like the old LFM model, where you had a famous issue to cut the qpf by 1/2 because of an extra 2 in the latent heat equations)

1 minute ago, Will - Rutgers said:

Don't we have slightly above average SST anomalies in the storm's path?

I'm not sure how anyone could use a model for a tropical system that isn't taking into account ocean conditions (but I guess that's the point and that's why the intensity forecasts are being discounted).  To my point, I've looked at the GFS in other tropical situations before and haven't seen these kind of predictions.

Not trying to argue btw... novice trying to make sense of things.

no argument. the big issue came about when they made the most recent changes to the GFS, as I understand things. They couldn't have the model perfectly coupled with the ocean in the atlantic apparently due to model stability and other issues. others in here know more about those changes than I do. But the discussion floating around is that this season, the changes have just not been good on the intensity side while on the track is hasn't been too bad. sort of a compromise done with this version which I hope they don't have to do with the next update.

[LongBeachSurfFreak]

Another factor, its been years since a major came out of the MDR during peak season. Multiple years without a good mixing event. Lots of untouched water ahead. 

[Jackstraw]

Recon dropped some AXBT's in front of the storm.  As the NHC mentioned it's heading into progressively warmer SST's. The 26 degree isotherm goes down to about 240 feet which is around the depth they were finding in the western gulf with Harvey.  I find that interesting as I would think that would not be as deep in the Atlantic as it is in the gulf.  

[KPITSnow]

Can someone explain to me what uncoupling is?