Major Hurricane Irma- STORM MODE

[78Blizzard]

The 18Z GFS didn't have Irma really going to town until between 03z and 06z, and then for the next 6 hours while crossing the Florida Straits, and for another 6 hours just before landfall.  So the next 3 hr update should tell us if that intensification process is underway, if that GFS run is correct.  We are about to get a new run right now.

[40/70 Benchmark]

3 minutes ago, CaWx said:

I'd like to know what flaws that is, I want to hear some reasoning. 

The IEW remnant and the residual impacts of Cuba....coupled with encroaching external factors, as evidenced by the impaired western flank of the system. 

ERCs coinciding with land interaction can do funny things to these systems.

I don't know all of the answers....believe me.

Not trying to pound my chest, I was all about this trending east, which obviously was azz backwards.

These things are humbling.

 

[Radtechwxman]

Irma def injested some dry air. I think that could really be hindering the strengthening for now

[cwc]

6 minutes ago, KPITSnow said:

Wait a minute...and I'm sorry I go off on a tangent, and I am not criticizing the NHC...but as of last night, they forecasted the storm to not be really weakened by Cuba, and stay 150-155 mph storm.

 

We also have several METS on here saying they believe this could be about to RI, so I would generally say cool it here.

and conditions change....clearly so do interpretations and opinions based upon analysis of those conditions

and y'know what, I'm a lawyer but there's about 30 different types of law that i'm not qualified to practice because I specialize in only a few.

 

[40/70 Benchmark]

3 minutes ago, donsutherland1 said:

Intensity forecasting is still very challenging. Models don't do well on it.

Absolutely.

[larrye]

3 minutes ago, CaWx said:

Don't get me wrong, I have great great respect for the NHC, but I would just like to here their reasononing behind not reaching Cat 4. If Irma was currently experiencing strong shearing, I'd be inclined to agree with their rationale. The reality is Irma isn't suppose to get those destructive shear readings until after passing the keys. Irma is about to strengthen, mark it down. It has all the fuel in the world and a clearing eye, things are going to be very interesting over the next 18hrs. 

If there's one thing I've learned from the past week ... it's not to speak in such absolutes. I'm not a met. But frankly ... over the past day or two, I've seen signs that Irma just isn't as well organized as it once was. The northern Cuba coast and the islands may not be mountainous, but there is still land interaction going on. And someone earlier did mention some possible dry air entrainment. Am I saying that it definitely won't strengthen once it makes it's northward turn? No. But somehow, my gut is telling me that this just isn't the storm it once was. I could be wrong.

[mempho]

Mandatory evacuation have been ordered for Levels A and B. Residents in Level B must begin evacuating immediately.

Pinellas County - Clearwater area

https://twitter.com/PinellasEM

wow...can't believe they waited so long.

Wow, I can't believe this. There are 5 evacuation zones in Pinellas and they've only evacuated two of them. If this thing bombs and funnels all that water into Tampa Bay- it's an epic disaster.

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[SN_Lover]

4 minutes ago, Buckeye05 said:

The outer eyewall that took over is looking rather oblong to me right now. Hmm... 

WV imagery is suggesting some drier air might have gotten into the core. Irma might be trying to mix that out. Wasn't much dry air, so should mix out fast. 

[jasons]

Even thought the eye has been offshore for several hours, it's only just now that the entire core is offshore, unimpeded by land friction, and has all that warm water for fuel. I really don't see any reason why Irma cannot further deepen until she hits the shear, which is still a ways off. Plenty of time to get back to a Cat 4. The surge will be beyond imagination.

[tim123]

Gfs gets down to 908 with landfall around ft myers..still think it's to far east. 

[TPAwx]

5 minutes ago, CaWx said:

I'd like to know what flaws that is, I want to hear some reasoning. 

Hurricane Irma Discussion Number  44
NWS National Hurricane Center Miami FL       AL112017
1100 PM EDT Sat Sep 09 2017

Irma's nearly 24-hour traversal of the north coast of Cuba appears
to have affected the hurricane's structure and intensity.  An
earlier NOAA Hurricane Hunter aircraft and a more recent Air Force
reconnaissance flight both measured maximum flight-level winds near
105 kt and surface winds near 95 kt.  The planes have reported
a double eyewall structure, which has also been observed in WSR-88D
Doppler radar data from Miami and Key West.  Irma's intensity has
been conservatively lowered to 105 kt, and I'd rather wait to lower
the winds further until we've seen the full data set from the Air
Force mission.

Irma has stuttered near the north coast of Cuba for the past few
hours, which may be a harbinger of the north-northwestward turn
that we've been waiting for.  In any event, Irma appears to be
moving very slowly toward the northwest, or 305/5 kt, very gradually
shifting away from the north coast of Cuba.  With the hurricane
located near a break in the subtropical ridge, it should turn
north-northwestward soon and accelerate near or along the west
coast of Florida during the next 36-48 hours.  Because of Irma's
hesitation to move northwestward, the new track guidance has shifted
ever so slightly westward, and the new NHC track is just a little
left of the previous one.  Although it is likely that the eye will
move near or over the Lower Keys Sunday morning, the hurricane's
angle of approach to the west coast of Florida makes it very
difficult to pinpoint exactly where Irma will cross the Florida Gulf
coast.

If an eyewall replacement occurs within the next 6-12 hours, Irma
has an opportunity to restrengthen a bit while it moves across the
Straits of Florida.  After that time, however, southwesterly shear
is expected to increase to 25-30 kt in about 24 hours and then
continue increasing through 48 hours.  This shear, in addition to
Irma's core interacting with Florida, is likely to cause a
weakening trend after 24 hours.  The new intensity guidance calls
for an adjustment from the previous forecast, although it
conservatively lies near the upper bound of the reliable models.
Irma is still expected to approach the Florida Keys and Florida
west coast as a major hurricane, and combined with its large size,
will produce significant storm surge flooding in those areas.

[beanskip]

Don't see a significant trend in strength or track on 0z GFS. 

[OceanStWx]

16 minutes ago, CaWx said:

IEW weakening and the OEW takening over. 85F+ water temps, not much shear before the keys, a warming eye, and clearing out and strengthening with possible RI. So many things are going for Irma not to reach 140mph again, and honestly I don't get what the NHC is basing their logic on. 

In addition to thinking that the core took a larger hit from Cuba than expected, they state:

If an eyewall replacement occurs within the next 6-12 hours, Irma
has an opportunity to restrengthen a bit while it moves across the
Straits of Florida.  After that time, however, southwesterly shear
is expected to increase to 25-30 kt in about 24 hours and then
continue increasing through 48 hours.  This shear, in addition to
Irma's core interacting with Florida, is likely to cause a
weakening trend after 24 hours.

[Floydbuster]

Irma may or may not achieve Cat 4 again. The pressure being in the low 930s and the core still being tight could allow her to make a run at Cat 4 near or over the Keys. Nevertheless, a tremendously dangerous hurricane.

[jaxjagman]

Getting some good rain

[mempho]

Also, Hillsborough County (Tampa) has only evacuated zone A. Am I the only who feels terror upon hearing this?

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[geddyweather]

13 minutes ago, JoMo said:

You think so? The whole "Irma isn't going to be weakened by Cuba" forecast last night sure hurts their credibility with their forecast now.  

Ok, and? As far as I know, a large portion of this board thought the same way given the variation in models, atmospheric conditions, water temps, etc. 

One thing to remember: we are placing an inordinate amount of responsibility on these guys at the NHC. They are experts, but guess what, they are also humans. Humans trying to predict an act of nature we do not fully understand yet. They've gotten a lot better at it, but there is still always work to be done. Not every wobble can be nailed, not every land interaction can be correctly interpreted, etc. At the end of the day, we still have a strong, deadly Category 3 hurricane heading for the Gulf Coast of FL. 

[David Reimer]

Ike made landfall as a 110 MPH Cat 2 hurricane near Galveston. A ~15' surge devastated the Bolivar peninsula and locations near Galveston with no seawall. The story from this storm for the United States will be the massive storm surge. If it makes it back up to Cat 4? Just another punch in a KO round. 

[Stormlover74]

NHC director on cnn now

[RUNNAWAYICEBERG]

14 minutes ago, donsutherland1 said:

Intensity forecasting is still very challenging. Models don't do well on it.

They don't and all we need to do is look back in Irma's history to see how guidance struggled to forecast cat 5 status, prior to attacking the Leeward Islands. 

I'd still be on edge down there... prep for the worst and hope for the best. 

[mempho]

Ike made landfall as a 110 MPH Cat 2 hurricane near Galveston. A ~15' surge devastated the Bolivar peninsula and locations near Galveston with no seawall. The story from this storm for the United States will be the massive storm surge. If it makes it back up to Cat 4? Just another punch in a KO round. 

Which is why I'm horrified by the "light" evacuation decisions made in Hillsborough and Pinneles counties. Something needs to be done about this right now, IMO.

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[Buckeye05]

SW side of the eyewall is no longer closed off with deep convection... 

[HillsdaleMIWeather]

New Raw T is up to 6.2

[40/70 Benchmark]

My honest opinion is that this system is going to leave a lasting impact, but not the transcendent one that most of us had feared.

Its going be like an Opal......bad enough, but not talked about all that frequently 15 years from now.

Carribean and Bahamas...different story.

That was epic.

I know that I'll get flamed for this, but not my intention to piss anyone off.

That is how I see it.

 

Dangerous storm, and I hope everyone in its path is prepared.

[jasons]

http://www.tampabay.com/news/weather/hurricanes/tampa-bay-area-rated-nations-most-vulnerable-to-hurricane-storm-surge/2249075

Of the eight most vulnerable cities in the United States, KCC's analysis put four in Florida, three on the Gulf Coast: Tampa; Miami (No. 4, with $80 billion in potential losses); Fort Myers (No. 5, with $70 billion in potential losses); and Sarasota (No. 7, with $50 billion in potential losses).

[F-5]

1 minute ago, Buckeye05 said:

SW side of the eyewall is no longer closed off with deep convection... 

That is most likely an illusion caused by the precip falling on top of KBYX

[TPAwx]

10 minutes ago, mempho said:

Also, Hillsborough County (Tampa) has only evacuated zone A. Am I the only who feels terror upon hearing this?

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Zone A covers a surge to 11 feet.  It's appropriate for the current 5-8 foot expected surge.  And obviously may not be if Irma strengthens or takes a different track beyond NHC's current expectations.

[Deck Pic]

1 minute ago, 40/70 Benchmark said:

My honest opinion is that this system is going to leave a lasting impact, but not the transcendent one that most of us had feared.

Its going be like an Opal......bad enough, but not talked about all that frequently 15 years from now.

Carribean and Bahamas...different story.

That was epic.

I know that I'll get flamed for this, but not my intention to piss anyone off.

That is how I see it.

Good post, but for the sake of accuracy, I would change the word "feared" to "hoped for"

[40/70 Benchmark]

Just now, Deck Pic said:

Good post, but for the sake of accuracy, I would change the word "feared" to "hoped for"

Diplomacy is a virtue-

[78Blizzard]

I had said last night when Irma began toying with the north coast of Cuba that the northern coast projects in a WNW direction, and that she would spend many hours hugging that coast.  Many were looking for that turn from the W to the WNW, but that turn wasn't going to take Irma away from Cuba.  That is essentially what happened and why the intensity went down.  I'm surprised that the NHC said that little weakening would occur, given that their projected path was along that coast.