Month: September 2017

Thoughts on strengthening

The following bothers me:

The pressure dropped 10 millibars, but the wind speed was held constant at 160 kts (184 m/h).  The decrease in pressure normally indicates an increase in wind speed potential.  However, the scientist think the storm is going through an eye wall replacement cycle, which will stop the wind speed from increasing.

Note: This storm is huge. If it makes it into the Gulf of Mexico, coastal Louisiana will feel the affects of it regardless of where it will make landfall.  The question is only one of severity.  The storm is still a long way off, but it is chugging alone.

ADV LAT LON TIME WIND PR STAT
27 17.10 -59.80 09/05/18Z 160 926 HURRICANE-5
28 17.40 -61.10 09/06/00Z 160 916 HURRICANE-5

 

BULLETIN
Hurricane Irma Intermediate Advisory Number 28A
NWS National Hurricane Center Miami FL AL112017
200 AM AST Wed Sep 06 2017

...EYE OF POTENTIALLY CATASTROPHIC CATEGORY 5 HURRICANE IRMA
PASSING OVER BARBUDA...


SUMMARY OF 200 AM AST...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...17.7N 61.8W
ABOUT 5 MI...10 KM N OF BARBUDA
ABOUT 40 MI...65 KM N OF ANTIGUA
MAXIMUM SUSTAINED WINDS...185 MPH...295 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...914 MB...26.99 INCHES

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Why the uncertainty in the turn?

Ok, it's very simple:  The turn is 5 days out.  Mathematically speaking, you can't accurately forecast 5 days out.  But, there is a small bit of information missing:  The steering current that is supposed to cause the turn is characterized as a "small wave." The question plaguing me is will this "small wave" be strong enough to allow a Cat 4 or 5 storm rotate on its axis?  It's 5 days out.  You can't know.

So, here's the deal:  The storm, as all storms do, wants to turn north, but there is a bulk of air that is forcing it to head west.  This bulk of air isn't supposed to let up until the 5th day allowing Irma to turn.  However.... 5 days is a long time in weather forecasting.

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