Matthew: No Certainty to Track, Difficult Forecast ahead

Updated: 2240z/18:40/6:40pm

This is a special update for Hurricane Matthew. No forecast will be given in this post.

Dillon has been on top of the daily forecasts in the last couple of weeks, and I was feeling like showing my face in here, so what better topic than to talk about Matthew! He certainly is a strong storm right now, a high end Category 4 storm with winds 145mph gusting to 172mph, located at just about 14.3°N 74.7°W, SE of Jamaica and S of Haiti. It has been continuing on a NW track, and this should take it between Jamaica and Haiti in the next 2 days.

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SO – Where is this strong storm heading? The short answer is, we really do not know…to an extent. As I said before it will continue to head on a NW track putting it between Haiti and Jamaica (closer to Haiti), and then making landfall on Cuba’s SE coastline by late afternoon Tuesday. This part is pretty consistent on the models, and the “easy” part to forecast. If anybody you know is travelling in the Western Caribbean in the next week, especially Cuba, Haiti, Dominican Republic, Bahama’s, Turks and Caico’s, etc, then they might want to change their plans. This is a very dangerous, and large storm, and it is unlikely to weaken that much.

Let’s get on to the more “scientific” stuff…what is steering this storm?

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Let’s dissect this map. Sub Tropical ridging (A) or the big blob of high pressure in the Atlantic is creating an anti-cyclonic flow (out of the center flow) of air, which is then flowing W (Easterly flow) into a broad area of Troughiness, or low pressure in the Eastern Gulf. The gradient caused by the Easterly flow out of the High is going to cause Matthew to be “pulled” or steered slightly to the NW as it makes it trek N, instead of going directly North. Part of the reason for this is also the shape of the high pressure. This brings me to the next point, our Upper Low S of the high pressure, that is dying out. This is deforming the anticyclonic flow and preventing it from “spreading” out as much, which would have likely caused Matthew to head west for a lot while longer. This UL also is tugging at Matthew a little bit, but that is not significant.

With all this in mind, you are left with a “path” between the trough in the eastern Gulf, and the Sub Tropical ridging that goes through the southern Bahamas and then off the Coast of Florida. The question is, what happens when it gets to the Bahama’s? The map above will be changed, and things in different positions. Let’s take a look at the GFS and see what it thinks will be the setup 4 days from now when Matthew is in the Bahamas:

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The ridging in the sub tropical Atlantic has moved slightly S, and the UL currently over the Ohio Valley has moved into the Atlantic, and we have another UL moving Northward into Maritime Canada. In addition to this, we have blocking, or ridging over Matthew. These leads to a difficult forecast, since there is no clear “path”. Furthermore, there are many piece of the puzzle that will determine the exact setup, or what is in place once Matthew get’s into the Bahamas.

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The progression of (A) which is our Upper Low, will have a big impact on the progression of (B), which then will leave room for (C) to come Northward (where exactly?) and then let (D) dive. Where (C) and (D) are when Matthew is in the Bahama’s and moving Northward is the KEY to where the eventual track will be. Piece (C), which is an Upper Low is not going to move due E across the US like normal low’s do, which would act as a “kicker” for Matthew pushing him out to sea. Instead, (C) will move almost NNE, which means that Matthew has more time to come UP the coast before either being kicked out when it eventually meets with (C), OR get phased into (C) which would pull it into the coastline, somewhere.

AS YOU CAN SEE – This is no easy forecast! At this point I would say the Carolina’s and outer banks need to keep a GOOD EYE on Matthew, as does SE Florida. Southern New England should keep a wary eye on it as well, but any impacts would not be until LATE next week/weekend, if any at all.

NWS will be launching extra data collection balloons and aircraft, etc., to help give the models more data to ingest to help with the forecast. Right now, there is NO USE to looking at the models outside of day 4. There is too much divergence in ensemble ideas at that point (see pic below), for a number of reasons:

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And finally, here is the current NHC cone. There is good reason they do not go past Day 4-5 on their cones. Also note that uncertainty expands by 75-mi per day on the cone.

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We will update you as Matthew gets closer. Enjoy the rest of the long weekend!

Forecaster: Remy M.

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