ATL: HARVEY - Models

[tarheelprogrammer]

12z GFS brings this back over SE TX in the 5-6 day period. Moving SE.

SE!? Yikes.

Southeast towards matagorda bay and then due east towards galveston bay. Very slow movement during hours 114-150.

This also shows that any change in movement speed will be critical. If the GFS is too fast then this thing could stall out before landfall, and head SE I believe. Eventually hitting LA I would guess. That would be a worse case scenario though.

[Siker]

12z UKMET just SW of Galveston:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 24 HOURS
FORECAST POSITION AT T+ 24 : 21.7N 91.5W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.08.2017 24 21.7N 91.5W 1007 23
0000UTC 24.08.2017 36 22.8N 92.1W 1004 29
1200UTC 24.08.2017 48 23.6N 92.5W 999 31
0000UTC 25.08.2017 60 24.7N 93.3W 993 41
1200UTC 25.08.2017 72 26.2N 94.4W 984 51
0000UTC 26.08.2017 84 27.8N 95.1W 972 63
1200UTC 26.08.2017 96 29.4N 95.1W 970 59
0000UTC 27.08.2017 108 30.4N 94.4W 977 50
1200UTC 27.08.2017 120 30.9N 93.7W 983 43
0000UTC 28.08.2017 132 31.4N 92.9W 988 36
1200UTC 28.08.2017 144 32.3N 92.3W 993 28

[Ivanhater]

Strengthening again over water off SW Louisiana

[ROCK]

Strengthening again over water off SW Louisiana

yep Mike the trof gives way to a big fat high that builds in and pushes this back into LA and eastward...its timing..

[ronyan]

I agree on the timing point if it slows down in the short term, but it is well inland into central TX on the GFS before the SE shift starts.

[Portastorm]

That 12z GFS run ... I'm laughing to keep from getting really worried.

Never seen the eye of a tropical system over our area. This would be a first.

[stormlover2013]

Would be devastating flooding

[shah83]

Check out the rainfall totals, about as bad as GFS ever gotten for any landfall, worldwide.

[PTrackerLA]

12z UKMET just SW of Galveston:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 24 HOURS
FORECAST POSITION AT T+ 24 : 21.7N 91.5W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.08.2017 24 21.7N 91.5W 1007 23
0000UTC 24.08.2017 36 22.8N 92.1W 1004 29
1200UTC 24.08.2017 48 23.6N 92.5W 999 31
0000UTC 25.08.2017 60 24.7N 93.3W 993 41
1200UTC 25.08.2017 72 26.2N 94.4W 984 51
0000UTC 26.08.2017 84 27.8N 95.1W 972 63
1200UTC 26.08.2017 96 29.4N 95.1W 970 59
0000UTC 27.08.2017 108 30.4N 94.4W 977 50
1200UTC 27.08.2017 120 30.9N 93.7W 983 43
0000UTC 28.08.2017 132 31.4N 92.9W 988 36
1200UTC 28.08.2017 144 32.3N 92.3W 993 28

UKMET holding firm on a Galveston hit but remains the eastern outlier. The rain totals on the 12z GFS are just obscene. 45.9" on the weatherbell Hi-res just north of Beaumont .

[shah83]

The CMC rainfall map is nuts

[CYCLONE MIKE]

Strengthening again over water off SW Louisiana

Well unless the euro suddenly changes its tune in a couple hours, looks like the gfs has fallen in line with the euro. we have pretty good agreement that whatever this becomes could definitely stall and get forced back out into the gulf and reorganize somewhat before making a second landfall in LA. Will really have to start watching that trough and shortwave that will be dropping down south in the coming days. Like yall said it all about the speed of the systems. If it slows down just a little bit wont make it as far inland before getting blocked and forced back into the gulf. Faster it goes much further inland before the north turn and will just get kicked up and out.

[hohnywx]

12z UKMET just SW of Galveston:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 24 HOURS
FORECAST POSITION AT T+ 24 : 21.7N 91.5W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.08.2017 24 21.7N 91.5W 1007 23
0000UTC 24.08.2017 36 22.8N 92.1W 1004 29
1200UTC 24.08.2017 48 23.6N 92.5W 999 31
0000UTC 25.08.2017 60 24.7N 93.3W 993 41
1200UTC 25.08.2017 72 26.2N 94.4W 984 51
0000UTC 26.08.2017 84 27.8N 95.1W 972 63
1200UTC 26.08.2017 96 29.4N 95.1W 970 59
0000UTC 27.08.2017 108 30.4N 94.4W 977 50
1200UTC 27.08.2017 120 30.9N 93.7W 983 43
0000UTC 28.08.2017 132 31.4N 92.9W 988 36
1200UTC 28.08.2017 144 32.3N 92.3W 993 28

UKMET holding firm on a Galveston hit but remains the eastern outlier. The rain totals on the 12z GFS are just obscene. 45.9" on the weatherbell Hi-res just north of Beaumont .

Reviewing performance statistics on the UKMET...looks like the model has a mean error of about 125mi at 96 hours out:



http://www.metoffice.gov.uk/weather/tro ... errors/nat

[Frank P]

Strengthening again over water off SW Louisiana

Well unless the euro suddenly changes its tune in a couple hours, looks like the gfs has fallen in line with the euro. we have pretty good agreement that whatever this becomes could definitely stall and get forced back out into the gulf and reorganize somewhat before making a second landfall in LA. Will really have to start watching that trough and shortwave that will be dropping down south in the coming days. Like yall said it all about the speed of the systems. If it slows down just a little bit wont make it as far inland before getting blocked and forced back into the gulf. Faster it goes much further inland before the north turn and will just get kicked up and out.

Kinda of reminds me a little of Allison, albeit not exactly the same track, but she went inland, dumped biblical amounts of water in Houston, then kicked back out in the Gulf and strengthened again... She really rack my house on the beach in Biloxi with at least 60mph winds...

[PTrackerLA]

Last time I saw rain total this high on the global models in the USA was the days before the August 2016 LA Flood. This could be another devastating even for TX and LA.

[stormreader]

12z UKMET just SW of Galveston:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 24 HOURS
FORECAST POSITION AT T+ 24 : 21.7N 91.5W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.08.2017 24 21.7N 91.5W 1007 23
0000UTC 24.08.2017 36 22.8N 92.1W 1004 29
1200UTC 24.08.2017 48 23.6N 92.5W 999 31
0000UTC 25.08.2017 60 24.7N 93.3W 993 41
1200UTC 25.08.2017 72 26.2N 94.4W 984 51
0000UTC 26.08.2017 84 27.8N 95.1W 972 63
1200UTC 26.08.2017 96 29.4N 95.1W 970 59
0000UTC 27.08.2017 108 30.4N 94.4W 977 50
1200UTC 27.08.2017 120 30.9N 93.7W 983 43
0000UTC 28.08.2017 132 31.4N 92.9W 988 36
1200UTC 28.08.2017 144 32.3N 92.3W 993 28

UKMET holding firm on a Galveston hit but remains the eastern outlier. The rain totals on the 12z GFS are just obscene. 45.9" on the weatherbell Hi-res just north of Beaumont .

Reviewing performance statistics on the UKMET...looks like the model has a mean error of about 125mi at 96 hours out:



http://www.metoffice.gov.uk/weather/tro ... errors/nat

This model is very close to my own thinking.

[CYCLONE MIKE]

Strengthening again over water off SW Louisiana

Well unless the euro suddenly changes its tune in a couple hours, looks like the gfs has fallen in line with the euro. we have pretty good agreement that whatever this becomes could definitely stall and get forced back out into the gulf and reorganize somewhat before making a second landfall in LA. Will really have to start watching that trough and shortwave that will be dropping down south in the coming days. Like yall said it all about the speed of the systems. If it slows down just a little bit wont make it as far inland before getting blocked and forced back into the gulf. Faster it goes much further inland before the north turn and will just get kicked up and out.

Kinda of reminds me a little of Allison, albeit not exactly the same track, but she went inland, dumped biblical amounts of water in Houston, then kicked back out in the Gulf and strengthened again... She really rack my house on the beach in Biloxi with at least 60mph winds...

Yeah that's what I'm thinking as well. I think the gfs has the right idea just maybe a little too fast with the nw movement of Harvey. Track seems reasonable but don't think it will make it as far inland before it stalls and gets turned back out into the gulf. Now if that trough slows and/or is weaker than forecast then it is definitely possible.

[hohnywx]

UKMET holding firm on a Galveston hit but remains the eastern outlier. The rain totals on the 12z GFS are just obscene. 45.9" on the weatherbell Hi-res just north of Beaumont .

Reviewing performance statistics on the UKMET...looks like the model has a mean error of about 125mi at 96 hours out:



http://www.metoffice.gov.uk/weather/tro ... errors/nat

This model is very close to my own thinking.

I followed the UKMET closely this season along with this past winter and it seems to have been performing very well (much above the GFS).

[Alyono]

looks like HMON has shifted southward into Mexico

[Rgv20]

looks like HMON has shifted southward into Mexico

Just took a quick glance at 12zHMON and HWRF and it looks like they slowed the timing down on the initial NW movement. Harvey is going to be a headache until final landfall!

[Alyono]

HWRF substantially weaker so far

The models are trending away from a cat 3 hurricane striking Texas