ATL: SANDY - Models

[RVAHudson]

Hey guys... I've been lurking here for a while, but a quick question... Am I seeing this correctly that this latest euro run has Sandy coming in farther south, along the Chesapeake Bay, 96-120 hours out, or am I looking at this completely wrong?

http://www.instantweathermaps.com/ECMWF ... b&hour=120

You are seeing that correctly.

This isn't the usual steering deal. Usually we're used to see systems pushed west by building high pressure to the north.

This time, Sandy will be "pulled" westward by the flow around the negatively-tilted trough over the upper midwest, it's acting like a magnet.

Moreover, the Sandy will have a lot of energy injected into it from that weather system. That baroclinic forcing will make this much larger than a normal tropical system. Winds will be very strong well north of the center. Could be historic.

This isn't without precedent, this has happened a lot of times over the years. It just hasn't happened since the internet has been around, so this a new experience for a lot of weather people.

MW

I was hoping that I was simply misinterpreting it. I work in public safety here in Richmond Virginia, and am trying to decide how plausible this scenario is, and consequently how prepared I should have my people at the station get; I have no meteorological training, just a hobby interest. Looking at that wind field makes me nervous, since we're only 70-100 miles SW of where the euro has her coming on shore. Then again, the GFS has her going much farther north, and I don't want to unduly alarm my people and look like Chicken Little

[artist]

In this case (noting the graphic just posted) there will be a strong high well to the north, the flow between that ridge and the inverted trough will create a super-highway in the steering layer, so to speak...and Sandy will be sling-shotted into the US coast.

Interesting the 0Z GFS from overnight missed the connection, but all of the other models since then have not.

MW

good to see you Mike, and as always, enjoy hearing & trust your opinions.

[tolakram]

Saved images from 12z euro run

[MWatkins]

Hey guys... I've been lurking here for a while, but a quick question... Am I seeing this correctly that this latest euro run has Sandy coming in farther south, along the Chesapeake Bay, 96-120 hours out, or am I looking at this completely wrong?

http://www.instantweathermaps.com/ECMWF ... b&hour=120

You are seeing that correctly.

This isn't the usual steering deal. Usually we're used to see systems pushed west by building high pressure to the north.

This time, Sandy will be "pulled" westward by the flow around the negatively-tilted trough over the upper midwest, it's acting like a magnet.

Moreover, the Sandy will have a lot of energy injected into it from that weather system. That baroclinic forcing will make this much larger than a normal tropical system. Winds will be very strong well north of the center. Could be historic.

This isn't without precedent, this has happened a lot of times over the years. It just hasn't happened since the internet has been around, so this a new experience for a lot of weather people.

MW

I was hoping that I was simply misinterpreting it. I work in public safety here in Richmond Virginia, and am trying to decide how plausible this scenario is, and consequently how prepared I should have my people at the station get; I have no meteorological training, just a hobby interest. Looking at that wind field makes me nervous, since we're only 70-100 miles SW of where the euro has her coming on shore. Then again, the GFS has her going much farther north, and I don't want to unduly alarm my people and look like Chicken Little

Yeah, that is the tough line you have to walk, but why you get paid the big bucks, right

It's easy to get absorbed into the individual model runs, but at the end of the day, the NHC does a great job of dealing with the probabilities in their official forecast track. They have a tremendous process and make verifiable forecasts accounting for what we do and don't know. That is worked into the cone of uncertainty...because nobody knows for sure how this going to go down 4-5 days out.

From a probabilistic standpoint, their forecasts are the best possible blend of the disparate guidance, and they know how to adjust for the uncertainty.

I did not know until a recent visit to the NHC that the wind probability graphic is a Monte Carlo simulation of 1000 outcomes of the storm, starting with the official forecast track and working from there. That wind speed probability graphic is probably your best reference for the likelihood of dealing with Sandy, although their probabilities are understated because the product wasn't built for hybrid storms.

There is some time before decisions have to be made (I think) so stick to your plan and good luck.

MW

[xironman]

I did not know until a recent visit to the NHC that the wind probability graphic is a Monte Carlo simulation of 1000 outcomes of the storm, starting with the official forecast track and working from there. That wind speed probability graphic is probably your best reference for the likelihood of dealing with Sandy, although their probabilities are understated because the product wasn't built for hybrid storms.

There is some time before decisions have to be made (I think) so stick to your plan and good luck.

MW

Interesting tidbit from the 11am NHC discussion

Code: Select all

NOTE THAT THE TROPICAL CYCLONE WIND SPEED PROBABILITIES ARE NOT
DESIGNED TO HANDLE THE TYPE OF STRUCTURAL CHANGES ANTICIPATED WITH
SANDY DURING THE FORECAST PERIOD. AS A RESULT...THESE PROBABILITIES
WILL UNDERESTIMATE THE ACTUAL RISK OF STRONG WINDS AWAY FROM THE
CENTER OF SANDY.

[ROCK]

did I see a 930MB at landfall? wow!! that is unbelievable if verified...

[gatorcane]

Look at the bend NW in the Bahamas by the 12Z Global FIM model that just ran....look how close Sandy is to Florida. Models are latching onto the building mid-atlantic ridge that is for sure:

[chris_fit]

I think it's going to do a loop in the N. Bahamas - More an more model support for this. Scare the pants off some people on the EC of FL...

[ROCK]

12Z NOGAPS

https://www.fnmoc.navy.mil/wxmap_cgi/cg ... t=Tropical

[Blown Away]

Look at the bend NW in the Bahamas by the 12Z Global FIM model that just ran....look how close Sandy is to Florida. Models are latching onto the building mid-atlantic ridge that is for sure:

Can you provide a link?

[storm4u]

did all the nws offices collect data for the 18z models or do we have to wait until 0z?

[Ptarmigan]

did I see a 930MB at landfall? wow!! that is unbelievable if verified...

If that is the case, that would be one of the most intense storm to hit the East Coast.

[gatorcane]

Link to FIM model:

http://fim.noaa.gov/

[WxGuy1]

did all the nws offices collect data for the 18z models or do we have to wait until 0z?

See http://www.spc.noaa.gov/exper/soundings/ and notice all the blue dots on the 1800 UTC image. I don't think I've ever seen nearly every NWS office in the CONUS launch special "off-hour" (e.g., 18 UTC, 6 UTC, etc.) like this before...

[Miami Storm Tracker]

Look at the bend NW in the Bahamas by the 12Z Global FIM model that just ran....look how close Sandy is to Florida. Models are latching onto the building mid-atlantic ridge that is for sure:

I know the NAM is the NAM but it has had two runs in a row that show some strange spreading out and doing a loop to the west as well.

[Aric Dunn]

18z NAM givien the satellite appearance and structure with all that mess well to its west some version of the 18z NAm may actually happen..

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

[ROCK]

did all the nws offices collect data for the 18z models or do we have to wait until 0z?

See http://www.spc.noaa.gov/exper/soundings/ and notice all the blue dots on the 1800 UTC image. I don't think I've ever seen nearly every NWS office in the CONUS launch special "off-hour" (e.g., 18 UTC, 6 UTC, etc.) like this before...

well they are sure concerned about it...Did they fly any G-IV missions? or they just relying on balloons?

[Evil Jeremy]

did all the nws offices collect data for the 18z models or do we have to wait until 0z?

See http://www.spc.noaa.gov/exper/soundings/ and notice all the blue dots on the 1800 UTC image. I don't think I've ever seen nearly every NWS office in the CONUS launch special "off-hour" (e.g., 18 UTC, 6 UTC, etc.) like this before...

well they are sure concerned about it...Did they fly any G-IV missions? or they just relying on balloons?

GIV this Saturday.

[ROCK]

ok that makes sense....they have plenty of obs right now along the EC

[ROCK]

12Z CMC...didnt see it posted on here....same as 0Z....brutal...

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation