ATL: DANNY - Models

[gatorcane]

I know it's far out but here is the high-resolution GFS showing a strengthening 975MB hurricane near the SE Bahamas. That is a 198 hour graphic and the margin of error is obviously very high for the model that far out:

[Blown Away]

Intensity guidance trending down

Slightly at the top end, but most of them maintain TS/Cat 1 whereas before many tanked Danny below TD...

[gatorcane]

You can see the difference between the model "titans" in what they think the long-range steering will look like as for potential CONUS impact, assuming Danny can stay together and is still around next week. ECMWF has a stronger and more expansive ridge than the GFS which extends all the way to Florida. That would prevent Danny from recurving no matter if it is a strong or weak system. The GFS has some ridging but there is enough of a weakness caused by a more amplified trough over New England that Danny could recurve east of the CONUS as the latest 06Z run show. But the GFS is known to break down ridges too quickly especially in the long-range so we will see what happens here.

ECMWF ensembles:


GFS ensembles:

[ConvergenceZone]

For those saying "recurve", I wouldn't say that quite yet. While it's true that most CV storms do recurve, I do know that it ultimately it comes down the setup down the road and the exact position of highs, troughs and gaps. Na never know..........

[RL3AO]

Thinking about the 10 to 16 day period. Typhoon Atsani will recurve and the models are showing a strong ridge building downstream south of Alaska. In response, you get an unseasonably strong trough into the West Coast next week. This should make a strong trough on the East Coast unlikely. Still means a weaker trough/zonal flow could turn the storm by the Bahamas, but its just something to keep in mind.

[floridasun78]

i was told NAVGEM not good for tropical system dont have good record

[wxman57]

If one of my forecasts turns out ever to be close to the NAVGEM (former NOGAPS) track then I know my forecast is wrong and I need to re-think the track.

[Dean4Storms]

12z ECM run will be vital, if it sticks with the more southern weaker route I would not ignore it. Doing so could be catastrophic to a forecast!

[jlauderdal]

If one of my forecasts turns out ever to be close to the NAVGEM (former NOGAPS) track then I know my forecast is wrong and I need to re-think the track.

there you go folks..all you need to know about navgem, entertainment purposes only

[PTrackerLA]

Wouldn't be surprised to see the 12z GFS trend more towards the EURO (given current appearance of Danny) but who knows. As far as upper level steering currents I wouldn't look at anything too closely after 192 hrs. How many times have we seen the "Mexico, wait now Nova Scotia" model run changes in just one day over the past years?

[Steve]

Thinking about the 10 to 16 day period. Typhoon Atsani will recurve and the models are showing a strong ridge building downstream south of Alaska. In response, you get an unseasonably strong trough into the West Coast next week. This should make a strong trough on the East Coast unlikely. Still means a weaker trough/zonal flow could turn the storm by the Bahamas, but its just something to keep in mind.

Big key. Recurves will indicate downstream troughing which might or might not pick up the system depending on how deep and relative latitude. Indications initially were possibly bends back to the west for dori (EP?) and Atsani but forecasted tracks were nudged right and north. Unfortunately the jtwc has been down for a day or so so I haven't been able to get the evolving forecast tracks put out by the U.S. Navy. Maybe there is an alternate site?

[wxman57]

12Z GFS is definitely indicating a clear recurve channel after the center moves west of 60W. That's not a patter which would indicate continued W-WNW movement. Can the ridge build back to the west fast enough to prevent recurvature east of the Bahamas/U.S.? We'll see...

[TheStormExpert]

I think that area mentioned over and around Bermuda by the NHC helps pave the way for the recurve.

[wxman57]

Here's a combo graphic with MSLP (1mb intervals) and 500mb heights (10m increments contoured) valid Monday evening. It's indicating a path north of the islands. Note the DEEP upper-level low sinking southeastward into the NE U.S. That's not a patter which would indicate an East U.S. threat.

[tolakram]

This appears to show a ridge a little stronger than last run.



http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=atl&pkg=z500a&runtime=2015081912&fh=132&xpos=0&ypos=211

[TheStormExpert]

It'll be interesting to see what that trough over the Great Lakes does.

[tolakram]

[gatorcane]

12Z GFS out through 189 hours looks like a clear recurve.

[Riptide]

Certainly not the most amplified weakness. Will probably meander around like it did in 06z.

[NCSTORMMAN]

12Z GFS out through 189 hours looks like a clear recurve.

A fish it is then. Good for the east coast and the usual too. We have a shield around the CONUS for the past 10 years for the most part. Interested in seeing if the Euro bows to the GFS on this one.