GFS Butterfly Effect

[MWatkins]

So far...the 00Z GFS is right in line with the 18Z guidence. In fact...I think I can see where the 12Z model went wrong in the steering layer...

First...the 132 hour GFS from the newest run:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_132m.gif

Note that the east coast ridge is starting to rebuild...

Now...the 144 hour GFS (same verify time) from the 12Z model...

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_144m.gif

Note that starting in the day 4/5 period in the model...the old GFS run had cut off a mid layer low and this was responsible for opening up the subsequent trough. By Day 6 (the above image) there' still a cut off 500MB low hanging around the coast of NC/MD...but there isn't one in the newest guidance. The low in the new run is already going up and over a 594DM ridge (no 594 ridge at all in the 12Z guidance).

This low hangs around in the extended period for the 12Z...allowing the next trough to "sweep" off the coast in the 8 to 11 day period. Now...I would "go all in" (poker speak) that the solution from the 18Z GFS will repeat in tonights run from days 8 to 11 (not out yet).... a digging trough in the central US...with the western Atlantic ridge holding strong. We'll see.

That one little low caused all this hubub today...once again proving Lorentz was right on the $.

MW

[MWatkins]

I hate replying to my own post...but...let's find out if my all-in bet won or lost...

New 00Z Guidance end of Day 11:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_264m.gif

Old 12Z GFS, same V-time:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_276m.gif

Perhaps the beginning of a negatively tilted H5 tough in the new guidance...the ridge extension is back to 80W or so.

Interesting...the cut-off low in the mid levels digs further to the south once it flips the ridge (once it gets to the eastern Atlantic) in the 12Z guidance...since it doesnt dig as much east of the US in the new guidance...it does not push the ridge back to the west in the 8-11 day period.

I suppose the key will be if a 500MB low cuts off from the main jet in another week. Again...I must stress anything past 120 hours is for speculation purposes only.

Once again..we'll wait and see.

MW

[bahamaswx]

Hence why accurate weather forecasting will never be possible.