Matthew Churning in the Caribbean, Much Uncertainty in Forecast

Matthew is now a Major Hurricane (meaning Category 3 or higher) located to the north of Venezuela and Colombia. In fact, there are Tropical Storm Warnings in effect for the northeastern coast of Colombia. Here is the latest information from the National Hurricane Center (11 AM EDT):

SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
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LOCATION...13.7N 70.8W
ABOUT 105 MI...170 KM NE OF PUNTA GALLINAS COLOMBIA
ABOUT 495 MI...800 KM SE OF KINGSTON JAMAICA
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WSW OR 255 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...968 MB...28.59 INCHES

Matthew is expected to continue west-southwestward for about the next 24 hours before making its northward turn. Now, where and when Matthew makes that northward turn has implications on where it will go after clearing Cuba. This is why the National Hurricane Center stated this:

It is important to remind users that average NHC track forecast
errors are around 175 miles at day 4 and 230 miles at day 5.
Therefore, it is too soon to rule out possible hurricane impacts
from Matthew in Florida.

It is important to note that the forecast cone is a projection of where the center of the system will go. Impacts can extend well outside the cone. Also, the cone is based on historical errors, and the center is predicted to be within the cone 67% of the time.

There is some concern for impacts on the United States. Generally, after 5 days, models lose skill in forecasting. However, with such high degree of uncertainty, there is decreased faith in the models. Here are the current spaghetti plots for Matthew:

In general, the models are in agreement of taking Matthew toward Jamaica and eastern Cuba and eventually into the Bahamas. However, the models have still been shifting east and west, and a shift in either direction has implications on later impacts.

This map shows the GFS Ensembles (GEFS). Basically, ensembles are just the same model (in this case, the GFS) run multiple times with slightly altered initial conditions. Thus, they help generate multiple different outcomes, giving us a probabilistic forecast. So, on this map, there is good agreement within the GFS ensembles that Matthew will move northward through the Bahamas to off the coast of the South Carolina. Afterward, there is much uncertainty. Now, let's look at the ECMWF Ensemble (EPS).

The ECMWF Ensembles are quite different. They are certain through about 48 hours continuing Matthew off to the west, then they become quite uncertain, ranging from the eastern Gulf of Mexico to well off the East Coast. Also notice the the EPS has a higher certainty in taking Matthew between Haiti and Cuba, whereas the GEFS had it over eastern Cuba.

So, what should you be doing? Well, if you're in Jamaica, eastern Cuba, or Haiti, you need be getting your plans and preparations done. It looks like those areas will be impacted in about 3 days. If you're in the Bahamas, start your preparations now as you are about 4 or 5 days out from impact. If you're along the East Coast of the U.S., you want to keep an eye on Matthew. Right now, it appears the main impacts will be increased swells and rip currents. Southeast Florida may have some gusty winds depending on how close Matthew gets to Florida.

Right now, it's still too early to give specifics on impacts to the U.S. or where Matthew will go after about 4 or 5 days out. So, the best advice is to keep watching if you're in the U.S., especially if you're along the East Coast.

Spaghetti Plots courtesy of TropicalTidbits.com
Ensemble plots courtesy of Dr. Brian Tang from the University of Albany: http://www.atmos.albany.edu/facstaff/tang/tcguidance/