10-16-2014, 04:39 AM
Rough day for Ana yesterday. The CPHC says that shear was a contributor to lack of convection on the west and northwest sides of Ana during the last 24-36 hours. Since models, including the SHIPS intensity model, did not show this, and there was no mention of the source of the shear, I will assume that it was from the far eastern edge of the upper level low that brought us rain Monday. But I'm also assuming that it was not the only factor.
The environment around Ana is slightly moister than 24 hours ago, but not by much. So she will still be less efficient at converting sea surface heat into wind, having to fight dry air feeding her circulation.
For the first time in almost 48 hours, the center of convection is centered over the center of circulation. This is allow strengthening, I have no doubt about that.
In 18 hours she is forecast to be over waters that are a little cooler. That means her optimum window of intensification is occurring during the diurnal minimum (daytime over the ocean).
So we have 1 factor that contributes to strengthening. Relaxation of shear on the west side of the storm. And 2 factors helping to keep that in check. Dry air, and the warming of the upper atmosphere during the day. Given the current improving satellite presentation, and the SHIPS intensity model showing only modest strengthening, I'd split the difference and figure on moderate strengthening. Maybe a low end hurricane with the peak of intensity late Friday night.
Now the path... her weakened state allowed lower level winds to guide her west-southwest during the past 24 hours. This pushed her well south of yesterday's CPHC forecast points. So the new forecast points were adjusted south and west to account for her actual position. Given the improving structure, she may be done being steered by the low level winds. So she should turn progressively more northwestward as she strengthens.
Will she turn enough northwestward to place the east side of the island in danger again? VERY POSSIBLY! Just not likely at this point.
Now the rain... when she's west of us, we are in strong southerly flow. In Puna, that means rain and lots of it. Good thing we don't have rivers here
In a nutshell... I've got plywood all ready for my windows. I've got water and gas for our generator. And I suggest you do the same. I don't think I'll need them this time, but this is a potential hurricane and it's close, so don't get fooled!
I will do updates as conditions warrant.
I don't see a delete button for older posts, sorry
The environment around Ana is slightly moister than 24 hours ago, but not by much. So she will still be less efficient at converting sea surface heat into wind, having to fight dry air feeding her circulation.
For the first time in almost 48 hours, the center of convection is centered over the center of circulation. This is allow strengthening, I have no doubt about that.
In 18 hours she is forecast to be over waters that are a little cooler. That means her optimum window of intensification is occurring during the diurnal minimum (daytime over the ocean).
So we have 1 factor that contributes to strengthening. Relaxation of shear on the west side of the storm. And 2 factors helping to keep that in check. Dry air, and the warming of the upper atmosphere during the day. Given the current improving satellite presentation, and the SHIPS intensity model showing only modest strengthening, I'd split the difference and figure on moderate strengthening. Maybe a low end hurricane with the peak of intensity late Friday night.
Now the path... her weakened state allowed lower level winds to guide her west-southwest during the past 24 hours. This pushed her well south of yesterday's CPHC forecast points. So the new forecast points were adjusted south and west to account for her actual position. Given the improving structure, she may be done being steered by the low level winds. So she should turn progressively more northwestward as she strengthens.
Will she turn enough northwestward to place the east side of the island in danger again? VERY POSSIBLY! Just not likely at this point.
Now the rain... when she's west of us, we are in strong southerly flow. In Puna, that means rain and lots of it. Good thing we don't have rivers here
In a nutshell... I've got plywood all ready for my windows. I've got water and gas for our generator. And I suggest you do the same. I don't think I'll need them this time, but this is a potential hurricane and it's close, so don't get fooled!
I will do updates as conditions warrant.
I don't see a delete button for older posts, sorry