ATL: IRMA - Models

[jlauderdal]

is 885mb pressure even possible in that vicinity (Carolinas) given the cooler water temps?

to put it in perspective, hugo was 935 at landfall...so we really going to shave off 50mb from that monster, unlikely

andrew 922

legendary typhoon tip was 870...tip was a massive storm in size too...this storm has a long way to go before getting close to hugo let alone near tip

all that said, any hurricane even a 1 is dangerous and irma is very likely going to be a major on approach to the united states so whatever it is if you are in a hurricane warning area dont take any of it lightly just because it might have underperformed these low pressures we are seeing modeled

[Hybridstorm_November2001]

ECMWF control run:

Donna's revenge on that run.

[MississippiWx]

The biggest key to take from the models that are showing sub 900mb strength is that the environment is going to be very supportive of an intense hurricane. A Cat 5 is possible upon approach to the coastline. Is it likely? No. However, models show that the environment is going to be very supportive. 900mb or less is probably a bit dramatic.

[Dean4Storms]

Somebody tell my at the 240hr ECM when you saw 500mb trough stretching from West TX across all of the SE USA clear out to the middle of the North Atlantic in early Sept.?
Me? Not buying it!

This has been well advertised for quite some time. take a look at the current 6-10 day outlook...it shows below normal temp probs to lake Okeechobee and local WFOs like Mobile are forecasting lows into the 50's in the Florida panhandle by next Thursday.

Yes, I am not doubting the trough by this Wed/Thur, I am talking about how long it takes to lift out and the disappearance of any ridge by 240hr.

[p1nheadlarry]

is 885mb pressure even possible in that vicinity (Carolinas) given the cooler water temps?

Someone correct me if I'm wrong, but the furthest north a Cat-5 has gone is about 29-30ºN and that was the Gulf. Also other factors are at hand there, such as dry continental air. We've seen storms ride the Gulf Stream and weaken, Irene comes to mind.

Not saying a 5 couldn't be north of 30ºN and hit the Carolinas, but stronger than Gilbert, Labor Day, etc? Doubt it. But there's a more scientific explanation as far as how much energy is required to reach and sustain that intensity given the conditions surrounding the hurricane; that's what the HWRF tries to solve after all.

[SapphireSea]

is 885mb pressure even possible in that vicinity (Carolinas) given the cooler water temps?

Someone correct me if I'm wrong, but the furthest north a Cat-5 has gone is about 29-30ºN and that was the Gulf. Also other factors are at hand there, such as dry continental air. We've seen storms ride the Gulf Stream and weaken, Irene comes to mind.

Not saying a 5 couldn't be north of 30ºN and hit the Carolinas, but stronger than Gilbert, Labor Day, etc? Doubt it. But there's a more scientific explanation as far as how much energy is required to reach and sustain that intensity given the conditions surrounding the hurricane; that's what the HWRF tries to solve after all.

Models are likely factoring in some instability forcing which is unrealistic to some extent, depending on trough interaction; it could be Baroclinic. As for the potential, i'd say that there is likely no strength limit at any latitude given that all the ingredients exist. (Warm SST, Instability, Low Shear).

[Steve]

is 885mb pressure even possible in that vicinity (Carolinas) given the cooler water temps?

Someone correct me if I'm wrong, but the furthest north a Cat-5 has gone is about 29-30ºN and that was the Gulf. Also other factors are at hand there, such as dry continental air. We've seen storms ride the Gulf Stream and weaken, Irene comes to mind.

Not saying a 5 couldn't be north of 30ºN and hit the Carolinas, but stronger than Gilbert, Labor Day, etc? Doubt it. But there's a more scientific explanation as far as how much energy is required to reach and sustain that intensity given the conditions surrounding the hurricane; that's what the HWRF tries to solve after all.

I can't think of any in recent history (outside of Camille <--- BSL is 30.3) though you'd think prior to keeping records era it's probably happened countless times. Cat 3/4 most likely if it landfalls appreciably farther north than Miami and that could be anywhere up the coast. I also think sub 900's are unrealistic though not impossible. Best guess would be this could get as far down as the 9-teens.

[Steve]

Oh, GFS is running for 18Z. If it hits the US, it's Run #9 in a row. About to go look at what the NAMs did at 18Z for the continental pattern even though they only go out 3.5 days. I expect a deep trough in the SE, but what it does is the 90 billion dollar questions. Last few runs had a massive front draped across the entire US East Coast before the low lifts out and high pressure builds back in from the NE and more importantly NW. Again, unfortunately they don't go out that far. Comments on NAM 12km/32km in a few minutes.

[toad strangler]

Through 48 18z GFS about one degree due W from 12z

[Bocadude85]

Though 60 hours the GFS is wsw of the 12z

[Steve]

Okay NAM 12km out to 84 hours (3.5 days so through 1am Thursday Central Time).

If you look at the upper pattern, the trough swings down but is centered farther east than the last several runs. Massive block nosing in off the Atlantic pushing back on it, and the high I've been talking about is centered over Manitoba/Saskatchewan. Unfortunately this stops at the critical point where you would see the evolution of the trough as everyone has been saying (split, cut off, lift out, whatever). Nam tracks below 25N are useless, but it is coming up on a track that would take it north of the Bahamas.


https://www.tropicaltidbits.com/analysi ... 0&ypos=300

[toad strangler]

Through 72 now a degree NW over 12z

[CrazyC83]

Could the Gulf models be those that hit Hispaniola and Puerto Rico first, leaving a shallower system that does not immediately respond to the trough?

[Alyono]

new GFS basically is Luis 2.0

[Steve]

78 Hour Comparison:

12Z - 19.44N 64.06W
18Z - 19.56N 64.97W

So between just north of due West and WNW. Faster could mean future trough/ridge implications. The slower it went the more likely the block would come in from Canada, but that's when it was showing landfalls farther up the coast.

[Kingarabian]

18z GFS through hour 72:

[Kingarabian]

18z GFS 72 -> 90:

[Bocadude85]

Though 96 hours the 18Z GFS is faster and southwest of the 12z

[WeatherEmperor]

Much firther SW. Dont like these trends...


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[Steve]

90 Hours looks to be a 1/2 degree west and maybe a hair south of 12Z. It's hard to position exactly on the center of what the model runs showed, but the difference now is:

12Z 20.47N 66.79W
18Z 20.47N 67.70W

So it's a degree farther west on the 18Z model at 90 Hours.

102 Hours:
12Z - 21.75N 69.22W
18Z - 21.62N 70.43W

So it picks up slightly more than a degree west in this run over 6 hours ago.