Heavy Rain/Snow, Tropical Weather, Weekly Outlook

Weekly Outlook October 3-9, 2016

There’s not much going on in the weather world right now is there? OK, we’re know you’re not that naive. We’ll get to the update on Matthew in a moment. Much of the remainder of the forecast is actually pretty simple.

The gloomy pattern we’ve been in will continue for one more day before the upper-level low pressure system responsible for it finally lifts out. High pressure starts to build in on Tuesday, and we stay dry through Friday.

After that? Well, that’s the $64,000 question, isn’t it? Here’s what’s going to be happening with the atmosphere. A cold front will start to approach from the west, while an upper-level trough of low pressure moves from the Plains states into the Great Lakes. By early Saturday, Matthew should be off the North Carolina coastline.

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GFS forecast for Saturday morning October 8. Note the trough of low pressure (green colors) moving into the Mississippi Valley, the ridge of high pressure off the East coast (red and orange colors), and Matthew just off the NC coast. Image provided by Tropical Tidbits.

How strong that trough is, as well as how strong the ridge of high pressure off the East Coast is, will determine where Matthew goes. The GFS (pictured above), sends the storm north-northeastward, as the trough pulls it in. Other models, such as the ECMWF, do not have a strong trough, and as such, it builds the ridge back in, stalling Matthew’s northward progress, and letting it mill around off the Carolina coast for a few days. Other models don’t build up the ridge to the east, and thus let Matthew head northeastward, farther out to sea, before the trough captures it and pulls it northward well east of New England. The upper-level energy that will help determine how deep that trough gets is still off the West Coast. Once it gets into the West Coast, and an area where there is a lot more data to feed into the models, they should start to converge on a solution, and thus give us a better idea, or at least a little more confidence, as to what will happen.

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GFS Ensemble forecast tracks for Hurricane Matthew. Image provided by Dr. Brian Tang, University at Albany.

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ECMWF Ensemble forecast tracks for Hurricane Matthew. Image provided by Dr. Brian Tang, University at Albany.

Before we get to what, if any, impacts Matthew may have on our area, there’s another problem. The models are picking up on this, but we don’t think they’re hitting it hard enough. We told you that a cold front would be coming in from the west. This is going to set up what is called a “Predecessor Rainfall Event” or PRE for short. This often happens up here ahead of tropical systems, and can even occur when the tropical system doesn’t even get within 500 miles of New England. This was the case with the devastating flooding we had in 1996 from Hurricane Lili and again in October of 2005. This also happened last year in South Carolina with offshore Hurricane Joaquin. In other words, even if Matthew does not come close to New England, we could be looking at extremely heavy rainfall around here on Saturday ahead of a cold front. Earlier this summer, we told you about an old rule of thumb “When in drought, leave it out”, when talking about rainfall. Well, we’ve got another rule of thumb for you “Droughts end in floods”. Just look at Texas from earlier this year to see that play out.

Monday: Partly to mostly cloudy with more showers and maybe even a rumble of thunder possible. High 64-71.

Monday night: Mostly cloudy, chance for a few more showers. Low 50-57.

Tuesday: Becoming partly sunny. High 58-65.

Tuesday night: Partly cloudy.  Low 44-51.

Wednesday: Partly to mostly sunny (yes, really, we mean it). High 60-67.

Thursday: Mostly sunny. High 65-72.

Friday: Sunshine and a few clouds. High 67-74.

Saturday: Becoming cloudy with rain developing. The rain could be heavy, especially at night. High 64-71.

Sunday: Cloudy with rain likely, possibly heavy at times. If Matthew is close enough, it will also be very windy. High 60-67.

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