Matthew Weakens Some Moving North Now
Update 5:05 PM: I am working on the next discussion but will wait until after the 18Z GFS run to finish and post. Hopefully will be completed before 7:00 PM.
Update: I have reviewed the 12Z GFS run and looks like a shift in forecast track. This shift is a result in a weaker upper-level trough off the northeast coast. I explained yesterday and today (paragraph near the bottom here) what effects a weak trough would have and this has been reflected in today’s models. If this forecast holds, the speed of Matthew will be the next variable to watch. A faster storm leads to a track further inland near South Carolina and North Carolina. A slower storm will miss land before being absorbed in the trough traveling across the US. I will also be keeping an eye out on the 12Z Euro model that should be available in a couple of hours. I might not be able to comment on the run at that time but will discuss all options later this afternoon in my update (there are other factors to consider in this situation that I will mention later). I must remind everyone that this is one forecast and could change at any time. The trend is for a close encounter with the NC coast which is why I am mentioning the forecast this far out. Please use this opportunity to prepare if you are along the east coast from Florida to North Carolina.
Hurricane Matthew
5:00 AM EDT on October 03, 2016
Location 15.2 N -74.9 W
Winds: 130 mph Gust: 160 mph
Pressure: 943 mb
Category: 4
Moving: N at 6 mph
Hurricane Matthew has weakened some overnight with winds down 10 mph to 130 mph. This storm is still a dangerous category 4 hurricane and this weakening hasn’t changed that fact.
Yesterday afternoon/evening, the storm motion was NW with some “wobbling” giving the impression that the motion was to the west. The center of the storm missed a couple of forecast points but not by much. The forecast points aren’t a set point that the storm must hit for the forecast track to be accurate. A position slightly to the west or east, unless it is a huge shift, is still within the cone of uncertainty and unlikely to make a difference this far away from land. Once you approach land these shifts one way or another could decide who make direct landfall and who doesn’t but that is a story for another day.
Now on this northward track, this storm is still forecast to travel very close to the west coast of Haiti. Hurricane warnings have been issued and this is a very dangerous storm that will not only bring strong winds to the country but very heavy rain. Rainfall forecasts for these areas are stunning and still definitely create major problems for the country. Jamaica will be on the western side of the storm. Strong winds will still affect the country, but the heavy rain will be a major problem for them as well.
This storm is forecast to be a category 3 hurricane as it makes its passage between the two countries. There is still a chance that it reaches the area as a category 4 hurricane but at this point the difference between the two categories is pretty much irrelevant in terms of how dangerous this storm will be.
The official forecast track hasn’t changed too much from the forecast track last night. Matthew will move passed the islands and set its sights on eastern Cuba. The mountainous terrain of Haiti and Jamaica will help disrupt the storm which will lead to some weakening during this time period. The storm will still be a dangerous hurricane as it approaches Cuba and like before, the specific classification is of little importance. They should expect to see the same type of conditions that Haiti and Jamaica experienced.
Once it moves over Cuba, the storm will have weakened to a category 2 hurricane. Increased wind shear over the storm at that time should help limit its intensification some keeping it away from the strength it is now. The forecast track at this point going forward is going to be uncertainty at this early stage. If you remember from my forecast discussion from yesterday afternoon, there are several key features to watch over the coming days that will ultimately decide the fate of Matthew.
The 06Z GFS run this morning still has the storm rounding the ridge in the mid-Atlantic by mid-week. An upper-level low and trough will be situated off the northeast coast which will serve to weaken the ridge over the Atlantic. As Matthew rounds the western side of the ridge it will begin to feel the tug of the weakness created by the trough. During this time, the storm will be large and very close to the east coast of the US which could bring some of it over the coastal sections even though the center may not make landfall. Since the storm is still forecast to be moving slowly it will meet the trough over US as it moves into the eastern US.
The weakness created earlier by the upper-trough will help give Matthew an opportunity to exit the coast ahead of the trough over the US. This should occur just off the North Carolina coast with the center potentially a couple of hundred miles off the coast.
Above the the GFS forecast showing the approaching trough from the west and the weakened ridge to the north. The 00Z Euro showed a similar situation but had the ridge a little stronger as the trough approaches from the west. The storm gets caught up by the ridge as the trough escapes to the north leaving Matthew in the mid-Atlantic.
So what does this all mean?
Things are very complicated and little changes in the features I mentioned can have a major impact on future tracks and interaction with land.
So if the upper-level trough is weaker, the ridge doesn’t get eroded and the storm stays close to the coast until the trough from the west pushes it out to sea. In this situation, the east coast could experience a landfall, most likely over the North Carolina coast. If the ridge is very strong and connect to the northeast CONUS the storm could make landfall south of North Carolina.
If the upper-trough is stronger, it could erode the ridge even more which will keep it further from the coast and most likely out to sea once the trough approaches.
In other words, if you live on the east coast, pay careful attention to the forecast and any changes to the forecast as it will probably change several times between now and the end of the week.
I will have an update later this afternoon.