ATL Invest 91L: Models

[mcheer23]

GFS has a sharper trough this run with much higher vorticity

Sure does...this is starting to get at least a bit more interesting

[stormlover2013]

Yeah seems like there is a window for opportunity for slight development

[mcheer23]

NAM, GFS and CMC are all more bullish tonight.

[Cpv17]

GFS rainfall totals can’t be right ..1 to 3” is all it’s showing in SETX.

[Haris]

Thats exactly my post on twitter! Do u follow me? Im harry... I want to be credited next time.

[Clearcloudz]

Thats exactly my post on twitter! Do u follow me? Im harry... I want to be credited next time.

I apologize, I found this on twitter while surfing and found it to be very helpful, should've credited you.
 https://twitter.com/harrywx1999/status/1006967607428124672

[Clearcloudz]

06Z NAM continues to show exactly what the 00Z NAM was showing a much more organized system by Sunday morning.

[i mg]https://www.tropicaltidbits.com/analysis/models/nam/2018061406/nam_mslp_pcpn_frzn_us_28.png[/img]

[Steve]

Morning Model Review

06Z NAM 12km/32km - Looks like closed low or depression. NAM available runs out 3.5 days (84 hours) so Sunday afternoon. Bulk of the rain through the period is offshore south of Louisiana.
https://www.tropicaltidbits.com/analysi ... 1406&fh=84

06Z GFS - Slightly less organized than the NAM though looking like some turning at the surface. Bulk of the rain is around Lake Charles/Sulphur but spreads into the Golden Triangle through 120 hours with 2-5"

00 CMC - Closed surface low comes ashore around Port Aransas/Corpus Christi in 90 hours (Sunday 7pm) with most of the rain to the east of the center. Through 144 hours, most of the rain is on the SE TX Coast though a large 8+ is over W and NW Houston.

00Z NAVGEM - Pulls a hook and moves low pressure into the NE Mexican Coast 150-200 miles south of Brownsville in about 72 hours. Scattered rainfall is mostly offshore and in Mexico.

06Z ICON - ICON tightens right after landfall around South Padre Island. Bulk of the rain on this model is in South Texas just north of McAllen in that sparsely populated area seeing 10"+.

(valid for) 12Z QPF shows a large area of 3-5" right along the SE Texas Coast.


FV3-GFS - Shows a surge with the bulk of the rain over Galveston/Galveston Bay. Does show a secondary surge after 7 days with a closed Low hitting SE LA from the SW. ECMWF is also hinting at this.

[jaguars_22]

my guess is that it will try to develop 150 miles off the coast of Texas and come ashore at Port A as a depression. It should have a day and a half over the water, could it surprise us all...

[Nederlander]

my guess is that it will try to develop 150 miles off the coast of Texas and come ashore at Port A as a depression. It should have a day and a half over the water, could it surprise us all...

After Harvey, I don’t put much stock into model strength forecasting in the Gulf. Consensus model support was TS to Cat 1... we all know how that turned out.. Not to get off-topic, but I have wondered how the models were so far off in regards to strength with Harvey.

[Steve]

my guess is that it will try to develop 150 miles off the coast of Texas and come ashore at Port A as a depression. It should have a day and a half over the water, could it surprise us all...

After Harvey, I don’t put much stock into model strength forecasting in the Gulf. Consensus model support was TS to Cat 1... we all know how that turned out.. Not to get off-topic, but I have wondered how the models were so far off in regards to strength with Harvey.

IMHO, NAM was the one that telegraphed it even though 20N is pretty much out of its range. I was guessing that it saw the potential and structure vs. the open wave GFS and EC had after it crossed the Yucatan. The biggest difference was that was August and not June. It's not impossible to have strong systems in June in the Gulf. But it's much rarer than August or September. The Western Gulf is weird though and often features tightening near to the shoreline. Models often under-forecast final intensity whereas they might see a higher end TS, you get a system making a run for Cat 2 or whatever. In this case, it seems pretty obvious there will be a surface circulation. I'm just not sure if it's going to tighten sufficiently to obtain classification. But I think most of coastal Texas and SC/SW LA should be in the rain by this weekend.

[stormreader]

Morning Model Review

06Z NAM 12km/32km - Looks like closed low or depression. NAM available runs out 3.5 days (84 hours) so Sunday afternoon. Bulk of the rain through the period is offshore south of Louisiana.
https://www.tropicaltidbits.com/analysi ... 1406&fh=84

06Z GFS - Slightly less organized than the NAM though looking like some turning at the surface. Bulk of the rain is around Lake Charles/Sulphur but spreads into the Golden Triangle through 120 hours with 2-5"

00 CMC - Closed surface low comes ashore around Port Aransas/Corpus Christi in 90 hours (Sunday 7pm) with most of the rain to the east of the center. Through 144 hours, most of the rain is on the SE TX Coast though a large 8+ is over W and NW Houston.

00Z NAVGEM - Pulls a hook and moves low pressure into the NE Mexican Coast 150-200 miles south of Brownsville in about 72 hours. Scattered rainfall is mostly offshore and in Mexico.

06Z ICON - ICON tightens right after landfall around South Padre Island. Bulk of the rain on this model is in South Texas just north of McAllen in that sparsely populated area seeing 10"+.

(valid for) 12Z QPF shows a large area of 3-5" right along the SE Texas Coast.


FV3-GFS - Shows a surge with the bulk of the rain over Galveston/Galveston Bay. Does show a secondary surge after 7 days with a closed Low hitting SE LA from the SW. ECMWF is also hinting at this.

Unusual last scenario....and you say Euro is hinting at it too.

[jaguars_22]

12z NAM is spinning her up right at TExMEx coast. HMM

[Steve]

....

Unusual last scenario....and you say Euro is hinting at it too.

Yeah. It shows up best on the dilatation axis run. You can see that around 96 hours, so it might just be a pressure pocket moving up as I don't have access to high enough resolutions to see what's really happening with that. It also noses the ridge from the SW Atlantic into the Gulf, so anything in Texas would probably just continue off around the perimeter of whatever ridging is in place to its east.

NAM 12Z is a little stronger and paralleling the Texas coast heading for somewhere between Matagora and Galveston Bays (possibly with a NE component toward the end?). It shows up nicely on the wind/precipitable water run.
https://www.tropicaltidbits.com/analysi ... 1412&fh=84

[Clearcloudz]

12Z NAM model continues to shows a system organizing 24 hours before coming ashore. This result would focus rainfall onto a specific location resulting in much higher amounts.

[Haris]

Thats exactly my post on twitter! Do u follow me? Im harry... I want to be credited next time.

I apologize, I found this on twitter while surfing and found it to be very helpful, should've credited you.
 https://twitter.com/harrywx1999/status/1006967607428124672

No problem bud! Just remember next time

[stormlover2013]

I would trust nam over Cmc for short range

[jaguars_22]

I wonder why the nam is showing the low moving northeast nearing texas coast?? Isnt there a High Pressure pushing west??

[Steve]

I wonder why the nam is showing the low moving northeast nearing texas coast?? Isnt there a High Pressure pushing west??

Might just be a nudge at the end of the run. The ICON was the most interesting run for the 12Z models I've seen so far. It gets to South Texas and just sort of stops and pumps in waves of rain as it's spinning down. The JMA seems to like South Texas as well.

Icon Total Precip:
https://www.tropicaltidbits.com/analysi ... 412&fh=180

[Weather150]

Don't use NAM for tropical weather forecasting. A huge NO NO.