ATL: HARVEY - Models

[poof121]

https://www.cyclocane.com/harvey-spaghetti-models/

Check out harvey models notice an Eastern shift 1 even brings him to the southern golf interesting week ahead

The one going into the southern gulf is just an extension of its current movement. Not an actual model.

[forecasterjack]

Gonna make the case new ECMWF would be one of the better case scenarios for Houston. N wind helps to drain Galveston Bay allowing for water to move into GOM. Continued onshore flow would do the opposite. Still a disaster either way.

[PTPatrick]

Looking at QPFs there are some decent discrepancies between models...GFS concentrates more toward the area west of Houston. Along I 10 toward San Antonio. It shows sub 10 inches for Houston this week. Euro shows 28 and nam is in the 2 foot neighborhood. Really hard to say. Sref means is 15 inches. Curious if any of the pros have found that one model has performed better in forecasting the actual previous amounts for Harvey?

[tolakram]

18z GFS so far, jumping around again.

[tolakram]

GFS significantly east again.

[tolakram]

[tolakram]

Total precip animation

[Steve]

Looks like GFS re-concentrates the heaviest precipitation at the coast and spreads it over Houston again.

[RL3AO]

GFS seems to match the observation of the frontal type boundary set up just inland near Houston. Should see near constant rainfall to the west of Houston for days.

[Garnetcat5]

Thoughts on dry air making an impact?

[PTPatrick]

Brian norcross was implying that Houston may have seen its worst high water mark in terms of flash flooding...basically making the point that grand totals of 2 ft over the next 4 days will not make water rise like it did last night. I see his point, certainly Houston would have to get very unlucky to have another 24 inch all at once deluge in the next couple day but it seems a risky pronouncement since given the volume of water around, it wouldn't take 24 inches to do the same flooding if it came quick enough. Suffice it to say tho, that even steady rain combined with more onshore flow isn't going to allow those bayous to go down quickly, if at all for a few days. And that doesn't even speak to The Brazos and San Jacinto watersheads, which as Brian pointed out could be elevated for weeks.

[Steve]

Thoughts on dry air making an impact?

It's going to be informative to watch what happens. This is an uncharted storm and as unique as they come. I feel like the models and satellites show both a northern boundary up against Harvey he can't cross and the trough that got into Missouri today tugging at it higher up. So initially it should concentrate the rain to the northern side of the system. But as it is almost back over water, does the convection bubble up from closer to the center? Different models have different ideas.

[stormlover2013]

Euro has been money on this!!!

[psyclone]

Brian norcross was implying that Houston may have seen its worst high water mark in terms of flash flooding...basically making the point that grand totals of 2 ft over the next 4 days will not make water rise like it did last night. I see his point, certainly Houston would have to get very unlucky to have another 24 inch all at once deluge in the next couple day but it seems a risky pronouncement since given the volume of water around, it wouldn't take 24 inches to do the same flooding if it came quick enough. Suffice it to say tho, that even steady rain combined with more onshore flow isn't going to allow those bayous to go down quickly, if at all for a few days. And that doesn't even speak to The Brazos and San Jacinto watersheads, which as Brian pointed out could be elevated for weeks.

eventually a point is reached where the water is so high it's tough to get a new crest. instead of additional rain yielding a new high water mark, it serves to slow the rate of decline. that may well happen in some of the watersheds.

[BRweather]

Man what a big flip in the GFS ensembles throughout the day

Think almost all now going NE

https://www.tropicaltidbits.com/analysis/models/gfs-ens/2017082718/gfs-ememb_lowlocs_us_19.png

[tolakram]

That is a huge flip.

[otowntiger]

That is a huge flip.

Sorry haven't been keeping up- how so??

[tolakram]

That is a huge flip.

[im g]http://i.imgur.com/SulAGHt.png[/img]

Sorry haven't been keeping up- how so??

Just this morning the GFS ensemble members were grouped mostly west, now they are east. It means the GFS is coming into line with the other models.

[PTrackerLA]

That is a huge flip.

[im g]http://i.imgur.com/SulAGHt.png[/img]

Sorry haven't been keeping up- how so??

Just this morning the GFS ensemble members were grouped mostly west, now they are east. It means the GFS is coming into line with the other models.

Not liking the trends tonight for Louisiana either. Tomorrow could be a rough day around here as well as SE Texas.

[Steve]

NAM rolling now. No 3km update yet. 12km sinks it toward and along the coastline to where it is half onshore in 18 hours stil. It concentrates the heaviest rains north of the center.

32km is offshore 21hours and north of the center also is getting the worst.

Last update before it comes in. 3km out to 7 hours looks like Houston and points north nonstop. It's 2 hours old so this is valid at I believe 2am. Ugh

https://www.tropicaltidbits.com/analysi ... 0&ypos=151