ETA trend with west trough

[btangy]

Look at successive runs of the ETA, not for the whereabouts of Frances (note the ETA has been all over the place), but for the 500mb pattern trend. Note that with each run of the ETA, the trough axis in the west is slightly further west (i.e. progresses slower) and is deeper and more positively tilted (all the say into Southern California). With such an amplified flow, usually a slower progressing solution is better. Also, a deeper trough in the west corresponds to a stronger ridge in the east. You can probably figure out where this is headed. The ETA upper level pattern supports those models which are further west and south with Frances.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_084m.gif

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_078m.gif

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_072m.gif

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_066m.gif

Edited: Also, the 00Z run of the GFS agrees much better with the ETA at 72-84hours. The 12Z models were way different with the handling of the western trough with the GFS much more progressive.