Monthly Archives: September 2017

Irma continues to fade

Monday, Sept 11, 2017

Irma continues to fade

Damage estimates far below early expectations

Irma’s winds keep getting weaker and weaker, but she still has plenty of water as northern Georgia is now finding out.  Heavy rains will be hard to transport westward over the Appalachians but Irma is going to try tonight and tomorrow.  Heaviest rains (2″-4″) should fall over eastern TN with lighter amounts working into Kentucky.  Some showers could reach as far north as the Ohio River toward morning.  Then, we’ll continue to see a few periods of rain around the Louisville area through Wednesday, at least.  An inch of rain is possible.

One forecaster who specializes in storm damage estimates yesterday predicted around $200 billion in insured damages from Irma.   By this morning, his forecast had dropped to $50 billion.  Other predictions were lower to start, but were down to $20 to $40 billion.  Still massive totals, but far less than authorities had led us believe.  What’s that old comment?  Question authority.

Hurricane Jose is still a potential problem.  Jose has been weakening and wandering aimlessly over the Atlantic for the past few days.  Today’s GFS model keeps Jose wandering for another day or two.  Then, the GFS pushes him westward for a few days then northwestward.  He should also be strengthening, but probably not to “major” hurricane.  Eventually, according to the GFS, Jose ends up in the vicinity of the Outer Banks by about next Tue/Wed and into New England a day or two later.

So, we may not see an end to Jose’s story until late next week.

Hurricane Irma, part 6

3 P.M. Sunday, Sept 10, 2017

Irma Should hit land soon

“Ground truth” so far has been far below NHC predictions

Weakening Irma is now a low Cat 3 and could drop to a 2 in a few hours.  Cuba took out a lot of Irma’s punch yesterday and she did rebound a bit overnight.  Now, however, even with the eye still at sea, a large part of the eastern half of Irma is over Florida.  Plus, a pocket of drier air is invading the southwestern quadrant of the storm.  The result is a weakening Irma.  Her current path should put her over Marco Island within a hour.  Then move north to Naples, Sanibel Island and Cape Coral during the next 4-5 hours.  With the exception of some of the Keys, the above mentioned places will most likely see the worst that Irma has to offer.  While certainly significant, the current wind field contains only about 73% of the force compared to the wind field predicted yesterday.

So, Irma in her present condition poses much less of a threat than had been predicted for days.  A lot of the extreme conditions that had been hyped for days will not happen, but 110-120 mph winds can still cause a LOT of damage.

Note:  It still looks like the remnants of Irma will bring rain to Kentucky beginning Tuesday and ending Thursday.  So kudos to the GFS model which was the first model I know of that picked up on this idea. (2-3 days ahead of the other major models.)  A lot of forecasters deride the GFS and prefer to use the European Model.  But, in this case the GFS was the clear winner.

Hurricane Irma, part 5

Sat. Sept 9, 2017

Landfall likely tomorrow in southwest Florida

Strongest winds still an open question

Not much more to say than in yesterday’s part 4 post.  Storm path pretty much the same forecast with adjustments probably no more than a few miles east or west.  Landfall should be around midday Sunday between Cape Coral (Fort Myers) and Port Elizabeth.  Then a slow journey north over Florida through early Monday.

I’m still not buying the wind forecast from the hurricane center.  As expected, Cuba has reduced Irma’s winds – now about 125 mph (Cat 3).  NHC predicts they will rebound to about 140 mph by landfall.  Continual interaction with Cuba and Florida should keep Irma from regaining that much strength.  I expect no more than 130 mph, and probably a little less.  Nevertheless, still a very potent hurricane.

It’s going to be a very agonizing wait for Floridians.

Hurricane Irma, part 4

Friday, Sept. 8, 2017

Irma down to a strong Category 4

Worst-case scenario coming into focus

At this point, it is mostly a case of waiting and waiting.  Forecast models have converged into a pretty strong consensus.  The only lingering question is how strong she’ll be at landfall?

After mostly giving up on the west coast (of Florida) solution on Wednesday, the models came roaring back yesterday.  Today, most of the holdouts have joined the chorus.  Irma will hit land over southwestern Florida Sunday morning and continue slowly north over the state for at least 24 hours.  Of the various ideas suggested by the models this week, that’s the “worst case scenario.”  And, now that’s the solution that seems to be most likely.

We can now be pretty confident  as to the where and when of landfall, but the strength remains a question.  NHC has it still with winds of 145 mph at landfall.  I feel that estimate is too high because from now until landfall its circulation will be affected by land masses.  That will disrupt the storm enough to weaken its winds by at least 10-15 mph.  That’s the low end of Cat 4, but Cat 3 is still a possibility.  Even with reduced winds, this storm is very bad news for Florida.

interim Irma update

6 P.M. Thursday, Sept.7.2017

Trend highlighted in earlier post today is now showing up strongly in latest GFS output.

Idea of landfall Sunday morning over southwest Florida is looking more and more likely.  If trend continues, it’s VERY bad news for Florida.  Latest NHC update is starting to incorporate these ideas.

Hurricane Irma, part 3

Thursday, Sept.7, 2017

Models shift a bit…looking worse for Florida

Model solutions converge as U.S. landfall gets closer.  However, an old model idea is regaining favor and that, if it happens, could be really bad news for Florida.  More on that later.

First, The official National Hurricane Center’s forecast track has shifted a little westward from yesterday.  That’s in line with the model consensus which tracks Irma either along, or just east of Florida’s east coast.   A similar storm last fall followed this path and Florida fared pretty well.  Irma is stronger, however, so this path would create more problems this time around.

Following that path, landfall would occur somewhere around the GA/SC coast.  That area would have the highest risk of devastating winds/storm surge.

The current forecast follows the path described above with Irma either over Miami or just off the coast by about 7-8 P.M. Saturday, slowly moving north overnight and Sunday.  During this time it is expected to be either a strong Category 4 or Category 5. (winds 145 mph or higher).  Landfall would occur Sunday night near the GA/SC border.

New thoughts:

While the above remains the official forecast, I’ll wait awhile before I totally agree.  Tuesday, I mentioned that the forecast models fell into two camps.  One brought Irma up the Florida east coast; the other took it inland over the Gulf side.  That idea disappeared yesterday as the models shifted to a more easterly path.  Today, several models have brought back that idea, in what amounts to a very ugly way.

Hurricanes are purely tropical systems, but as they approach North America and recurve (turn) northward mid-latitude wind systems also get involved in the steering mechanism.  Our current cool weather has arrived do to an unseasonably strong upper level trough digging into eastern North America.  Apparently, yesterday the models felt the trough was stronger (and slower) than it actually is.  The result was to predict the storm path farther east.  Today, however, the models have corrected yesterday’s overreach.  That greatly reduces the trough’s ability to encourage Irma to turn northeast over the weekend as mid-latitude winds will become very weak.  How does that change things?

The models predicting the movement of Irma into the Gulf have also slowed her speed, probably due to the relaxing of the wind fields over the U.S.  They have also delayed the northward turn.  The result is Irma drifting between Florida and Cuba Saturday night, then turning northward Sunday into southwest Florida.  Furthermore, the delay will allow steering currents to weaken even more.  As a result, this model idea would allow a dying Irma to remain over Florida 24-36 hours!  You don’t even want to think about that scenario.

I’m hoping the models will present a clearer picture by tomorrow.  I’m also hoping that the current NHC prediction is very close to correct.  If it isn’t and the slower developing idea wins out, Irma will become a name we’ll remember for a long, long time.

Personally, I’m getting very worried about Florida.

Hurricane Irma, part 2

Wed. Sept. 6, 2017


Models change:  better prospects for Florida

Today’s model runs are shifting the path of Irma slightly north and the expected turn north a little sooner.  That adds up to slightly better news for residents of Florida.  Most models now have Irma hugging the Florida east coast Saturday night and Sunday.  That path would still create huge problems for the coast, but not as much as a direct hit would.

Florida’s slightly better news means worse news for Georgia and South Carolina.  Model consensus now puts landfall near the GA/SC border late Sunday.  Irma should still be a major hurricane so that area could well bear the brunt of the winds/storm surge.

Beyond that, a weakened Irma is expected to diminish while spreading tropical rains northward along the Atlantic Coast (mostly east of the Appalachians).

Other model ideas:

There is pretty good model agreement up to about 3-4 days.  After that, two models offer “outlier” solutions.

First, the Canadian model is much farther east than the consensus.  It keeps Irma far enough east of Florida’s east coast to ease the coastal erosion significantly.  Irma then brushes by the Outer Banks.  Later, a much weakened Irma could make landfall near Cape Cod.  At the moment, that’s the best case scenario for the U.S.

Second, the GFS continues to hang on to its ideas mentioned yesterday.  And, it is faster than the other models by 12-24 hours.  It is the only model to push the remnants of Irma northwest. It still pushes the dying storm over the lower Ohio Valley by Tue/Wed.

Those two model ideas sum up the frustrations facing forecasters every day.  The farther you try to look into the future, the more the uncertainty increases.   Two reliable models (for the short term), starting out with the same data, predicting the same major storm’s path.  At 6-7 days time, one has the parent system over western KY and the other has it near Cape Cod.  Go figure?

My ideas:

History has shown me that once a hurricane track forecast changes to a more easterly path, that trend usually continues.  And, very little forecast path change is likely in the 48 hours leading up to landfall or near miss.

With this in mind, I believe that by tomorrow morning (Thursday) the model consensus will continue to shift eastward.  Not as far as the Canadian, but in that direction.  By Friday, the forecast will be pretty well “locked in” with only minor adjustments after that.

Thus, I expect Irma will not make a direct hit on Florida.  East Florida will suffer from high surf and beach erosion, but problems will be minor to what a direct hit would create.

As Irma heads NNE, I expect the North Carolina coast to be hit hard.  It’s possible it could only be the Outer Banks area, not the whole coast.  After that, I don’t even want to speculate.

Stay tuned, by tomorrow we could have a whole set of new ideas!


Hurricane Irma

Irma’s a Category 5


Irma is a long way from the U.S., but some islands like the U.S. and British Virgin Islands will get hit hard soon.  After that the various models seem to fall into two central ideas – both bring Irma WNW staying just north of Puerto Rico and Cuba (while wiping out the Turks and Caicos) until things change while she’s just south of Florida.  About half the models bring the storm north either over Florida or just off the east coast.  Then a move inland anywhere between Georgia and Myrtle Beach. (Hilton Head ?)
   Second set of models brings Irma along the west coast of Florida with landfall over the panhandle to as far west as Mobile.
   It’s anybody’s guess at this time – a few minor changes over the next few days could alter the forecast significantly.
As to intensity, Irma’s a Category 5 now.  The strongest hurricane ever observed purely over the Atlantic Ocean.  Stronger hurricanes have formed over the Atlantic Basin, but they were in either the Gulf of Mexico or the Caribbean Sea.
     While hurricane position forecasting has steadily improved, the same cannot be said for intensity forecasts.  They are notoriously poor!  Just yesterday the forecast for Irma was to remain a Cat 3 through tomorrow, then slowly weaken; today she’s a Cat 5. Today’s prediction is for Irma to slowly weaken over the next five days, but remain a major hurricane.
P.S. Just a final thought…The morning run of the U.S. workhorse forecast model, the GFS, brings Irma northward along the Florida Coast this weekend with landfall near the Georgia/South Carolina border.  The GFS then weakens the storm as it drifts northwest.  Finally, the GFS has Irma’s remnants fading away over Kentucky next Wed/Thu.  Just something to think about.
(I think you should NEVER believe  a weather forecast that far in advance – let’s see what happens.)