June 20: Watching the Tropics, Daily Links


Pleasant weather in store for us today and most of tomorrow, before our attention shifts to a developing system in the Gulf of Mexico that will bring us heavy rain later this week.  Temperatures today will top out around 90°:

Here’s the really good news — the humidity won’t be a problem at all!  Dew points will stay in the 50s all day, which is right where we want to be on the “muggy meter”:

Increasing mugginess tomorrow, and temperatures will be a degree or two hotter as well:

A good chance of showers and thunderstorms moves in Thursday, Friday and Saturday, courtesy of a tropical system brewing in the Gulf of Mexico — that system is currently classified as a “Potential Tropical Cyclone,” but it could be upgraded to Tropical Storm Cindy later today:

If you’re wondering what the heck a potential tropical cyclone is, you’re not alone — it’s a new product from the National Hurricane Center.  Here’s their official statement:

NHC will in 2017 have the option to issue advisories, watches, and warnings for disturbances that are not yet a tropical cyclone, but which pose the threat of bringing tropical storm or hurricane conditions to land areas within 48 hours. Under previous longstanding NWS policy, it has not been permitted to issue a hurricane or tropical storm watch or warning until after a tropical cyclone had formed. Advances in forecasting over the past decade or so, however, now allow the confident prediction of tropical cyclone impacts while these systems are still in the developmental stage. For these land-threatening “potential tropical cyclones”, NHC will now issue the full suite of text, graphical, and watch/warning products that previously has only been issued for ongoing tropical cyclones.

Okay then.  Regardless of the official classification, this system is going to be a troublemaker — the NHC’s forecast path brings the center of circulation onshore near the Sabine River (the border between Texas and Louisiana) tomorrow night:

The main threat will be the abundant moisture that will surge northward on the eastern side of the center of circulation.  Significant flooding is possible along the Gulf Coast of Louisiana, Mississippi and Alabama — the Weather Prediction Center’s rainfall outlook shows the potential of more than a foot of rain between now and Friday morning:

Locally, our weather will become unsettled on Thursday, as some of the moisture sneaks up into our neck of the woods.  An early look at Futurecast (the high-resolution NAM model, if you’re curious about the nerdy weather details) shows just a slight chance of a shower in southern Middle Tennessee Wednesday afternoon, with a much better chance of scattered showers and thunderstorms late Wednesday night and Thursday:

The best chance of widespread heavy rainfall heads our way late Friday into early Saturday…at least, that’s the way it looks right now.  Because the tropical system in question is so disorganized, the various forecast models are having a hard time figuring out what it’s going to do.  I’m heavily tilting my forecast toward the (generally) more-reliable European forecast model, which shows 2″-4″ of rainfall across most of the Midstate through Saturday:

The Weather Prediction Center is mostly following along with that, although they’re shifting the heaviest rain just slightly southward:
That’s enough to cause localized flooding, so plan on staying weather-aware Friday and Saturday — we’ll keep you updated if any watches, warnings or advisories are issued.  And keep in mind: there WILL be changes to this forecast.  We’re still a few days away from the heaviest rain arriving in our area, so there’s a lot that can happen between now and then.

While the heaviest rain should be out of here by Sunday, it looks like there will still be enough moisture hanging out to produce some scattered showers and storms.  I’ll leave the rain chances at slightly lower than 50-50, just because there’s still so much uncertainty about the specifics of Friday and Saturday’s weather:

We’ll dry out early next week — if we’re really lucky the dry weather will arrive already on Sunday, but I wouldn’t wager on that just yet.




About paulheggen33

Morning meteorologist for WNCN-TV in Raleigh.
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