ATL: IRMA - Models

[tolakram]

00z GFS

[Steve]

GFS hits lowest pressure on the 6 hour run at 18 hours so valid 2PM EDT tomorrow. Maybe a move just West of Due North? Drops it to 911 which would be coincidental with the day after and then has it up to 925 at 24 hours inland in SW FL. 30 hours a hair North of Tampa Metro. 36 hours over +/- Gainesville

I don't know how much I agree with the GFS pressure. Recon will confirm everything, but there are some raggedy aspects of Irma with the slots between some of the bands and the environment won't be all that great. So I guess if the GFS is right, we should be in a deepening phase until tomorrow afternoon.

[LAwxrgal]

I don't know if I necessarily agree with the numbers on the GFS, I think they've been overcooked for days, but it's been remarkably consistent with the trend of intensification once it clears Cuba.

[brghteys1216]

Thoughts on 00z GFS? More east over peninsula.

[shah83]

The GFS doesn't seem to show a storm suffering from shear until well above Tampa...because it think it will be far enough east of the front?

[Otown_Wx]

What's making the GFS turn east after landfall? Closer to Orlando then shifting back west? Is that possible?

[NFLnut]

That trough in the Gulf is really diving ... How will Irma make much more westward progress? Is the dramatic slowdown in forward progress a sign of an impending turn? Just wondering ...

At the time of your post, it had already made a northward turn an hour earlier.

[NFLnut]

What's making the GFS turn east after landfall? Closer to Orlando then shifting back west? Is that possible?

Magic 8 ball says "Most Likely Not."

NOTE: This is my opinion only and should not be used to make decisions which concern life, limb or property.

[skillz]

What's making the GFS turn east after landfall? Closer to Orlando then shifting back west? Is that possible?

I'm wondering the same exact thing.....

[Digital-TC-Chaser]

[Digital-TC-Chaser]

[Alyono]

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC AND ATLANTIC

GLOBAL MODEL DATA TIME 0000UTC 10.09.2017

HURRICANE IRMA ANALYSED POSITION : 23.6N 80.5W

ATCF IDENTIFIER : AL112017

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 10.09.2017 0 23.6N 80.5W 938 89
1200UTC 10.09.2017 12 24.7N 81.2W 939 87
0000UTC 11.09.2017 24 26.9N 81.4W 944 76
1200UTC 11.09.2017 36 29.7N 82.4W 964 64
0000UTC 12.09.2017 48 32.5N 83.8W 984 38
1200UTC 12.09.2017 60 34.9N 86.1W 997 22
0000UTC 13.09.2017 72 35.8N 88.7W 1001 14
1200UTC 13.09.2017 84 35.4N 90.0W 1005 16
0000UTC 14.09.2017 96 CEASED TRACKING

[Blinhart]

So why don't we see her decide to dig back down into the GoM after moving into GA/AL and then restrengthen. Right now it doesn't look like that will happen, but hey you never know.

[CFLHurricane]

I'm not posting this to argue because other than caneman, I'm the last one to use the term you said did not contribute to the discussion. However, it has been better than the NHC at every point (12, 24, 48, 72 and 96 hours) for Irma over time spanning since August 30th. NHC has done great, I'm not knocking them. But in this particular case, reliance on the Euro up to a point would not have been a bad decision. Obviously that is not the case for every storm or even the future of Irma. That's not my point. But if you followed EC as your sole source for Irma, you'd generally know closer than any other source what's going to be up for the next 5 days (for the past 11 days).

Steve is right. I despise the term King Euro. Not because it's not good but because you're always better to go with the blend. The Euro also has misses so that term can lull people into a false sense of security or panic. However, I give credit where credit is due. The Euro, UKMET and TVCN have been pretty spot on with this system. The UKMET had the West trend well before the Euro. Having said all that..... you have to give credit where credit is due, IRMA has been shockingly well modeled by above modeling. In fact, I can't recall a storm so well modeled. Any one else? The NHC has also modeled this very well by knowing where and how to weight each model

Obviously a poor term I echoed.
Having never Used it before, I shall clearly never use it again.
It has had a dominant influence on my perception of the current storm, and I'll just leave it at that.

Peace and Godspeed

No need to explain. Model rivalry improves the accuracy of them all. Not to mention if one's life depended on one model's forecast, we all know who they'd come crawling to

[Steve]

What's making the GFS turn east after landfall? Closer to Orlando then shifting back west? Is that possible?

I haven't looked at the numerical plots, but it doesn't look like has an eastern component. It goes inland and sort of just tracks north and then moves NNW. You can see how dry the air is as in the deep south as you get maybe 2" of rain out of it toward Memphis before it tries to get out but get absorbed. One very interesting thing to note about the GFS is the way it treats the subsequent high pressure after the one that is north of Irma moves out then the next trough comes through. Cold high mid-late summer means you look south or southeast for tropical activity in that pattern. GFS loops Jose by the Bahamas and comes back up aiming toward the Carolinas with high pressure pushing against it from the Atlantic and a block over top. Maybe there's an alleyway out Northeast, but this pattern should bring Jose into the US. GFS underestimates ridging in the NE US and Western Atlantic. When it shows one 7-8 days out, you have to wonder if we don't have a 3rd threat. Also Jose is piling up the ACE as well and probably taking some of the heat out of the western Atlantic.

https://www.tropicaltidbits.com/analysi ... 0&ypos=400

[MrJames]

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC AND ATLANTIC

GLOBAL MODEL DATA TIME 0000UTC 10.09.2017

HURRICANE IRMA ANALYSED POSITION : 23.6N 80.5W

ATCF IDENTIFIER : AL112017

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 10.09.2017 0 23.6N 80.5W 938 89
1200UTC 10.09.2017 12 24.7N 81.2W 939 87
0000UTC 11.09.2017 24 26.9N 81.4W 944 76
1200UTC 11.09.2017 36 29.7N 82.4W 964 64
0000UTC 12.09.2017 48 32.5N 83.8W 984 38
1200UTC 12.09.2017 60 34.9N 86.1W 997 22
0000UTC 13.09.2017 72 35.8N 88.7W 1001 14
1200UTC 13.09.2017 84 35.4N 90.0W 1005 16
0000UTC 14.09.2017 96 CEASED TRACKING

Mapped

Shift to the east.

[WxGuy1]

So why don't we see her decide to dig back down into the GoM after moving into GA/AL and then restrengthen. Right now it doesn't look like that will happen, but hey you never know.

Because there's an upper-tropospheric trough in the south-central U.S. into the western/central Gulf of Mexico by the time Irma gets to the central GA/AL line. Irma is not going back into the Gulf considering the 40-60 kt southwesterly 200 mb flow (it strengthens after the 48 hr forecast period shown in the image below).

It's not going back into the Gulf, at least not as a tropical cyclone (I haven't looked out far enough to see if there are any indications of a Hurricane Ivan-like path. However, given the rarity of that evolution, I'll say Irma most likely will be done as a tropical cyclone in a few days).

[PTPatrick]

Ukmet looks weird...but gfs shifted east too so who knows. It's initialized too high though on pressure and wind. Of note Is it no longer calls for strengthening...just stasis.

[Steve]

GFS with the block on Jose while it stalls out and grows larger around 210. It probably triples in size over those 8+ days. Still stalled out and still getting larger at 216. Another big high is coming across but there's a break in the shading. I wouldn't trust this out to 210, but the GFS usually goes the other way with weather. The EPAC storm coming in off Mexico toward New Mexico is interesting too. Not sure if Katia remains spark the genesis because I haven't been watching. Out to 222 and still stalls out Jose off the NC Coast. Jose wants to turn us back to a -AMO.

HWRF coming into SW FL at 18 hours/2pm tomorrow - skirts the coast at Naples and goes in about Cape Coral.
https://www.tropicaltidbits.com/analysi ... 0&ypos=300

HMON comes into Cape Coral

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

If they're right, hang in their Sanibel!

[GBPackMan]

Another piece of the puzzle related to the trough is it has kept the temperatures 10-15 degrees cooler here in the western panhandle (down to low 60s at night), so as it tracks north, that cooler dryer air is sucked in likely dropping the intensity further.
While GFS shows the pressure drop, and other models leveling off around 920-950, in my opinion this should start affecting it soon as the upper level cooler air helps weaken it slightly before mainland landfall, meaning slightly elevated pressure as it heads north-ish, not dropping pressure. This could be a possibility to help lessen the impact in the northern end of the state, IF it happens soon enough.
Granted the sheer size and power of this storm may mean it brushes it off and keeps the power running all the way into GA.