Tuesday, July 12, 2011

Computers see tropical system for S.C. coast

In the midst of all this talk about heat and high humidity, here's something else to think about.

Two of the more highly regarded computer models are hinting at the development of a tropical system late this weekend or early next week off the Carolinas coast.

It's certainly well before the peak of the tropical weather season, but records show that a storm forms off the Southeast Coast once every two years, on average. So it's not beyond the realm of possibility.

We're not talking about Hurricane Hugo here. The GFS and European models show some sort of tropical low or weak tropical storm forming off the South Carolina coast, then meandering along the coast for a day before sprinting out to sea and intensifying (after it leaves the coast).

The catalyst for this formation would be a cold front that is expected to plow into our region late Wednesday and push into southern South Carolina and Georgia by later Thursday or Friday. The idea, according to the computers, is that low pressure would form along the front and then take on tropical characteristics.

It could mean some big-time rain for the eastern half of South Carolina and probably southeast North Carolina. That's an area still suffering from drought, and heavy rain would do wonders in helping put out some stubborn wildfires.

We'll keep an eye on this over the next few days, because while the system would be too far away from Charlotte for much local impact, it certainly could provide a rainy day (or two) at the beach for local folks down there on vacation.

Dew Points: The real culprit in our current heat wave is the humidity, which can be measured by looking at dew point temperatures.

While the actual air temperature has climbed near 100 degrees in some places Tuesday afternoon, it's the dew point readings that are crazy high. Albemarle's reading at 2 p.m. was 81 degrees. Keep in mind that anything above 65 is humid, and anything above 70 is nasty. An 81-degree dew point temperature is like something you'd find on the Saudi Arabian coast.

Speaking of which ... the supposed world record for highest dew point temperature is 95, set July 8, 2003, in the Saudi city of Dhahrain.


Anonymous said...

So what is the Charlotte dewpoint record, and the NC record?

nimbus3553 said...

95 degree dewpoint, but what temp?? 94 d.p.and 120 degrees F. (not out the question in a desert),= 50% r.h. ... not too shabby. 96 d.p. and 110 degrees F. = 70% r.h. now that sucks.

Anonymous said...

You weather guys keep telling us it's not the temp, it's the humidity, and then you tell us what the temps will be the next few days. Is the humidity going to go down!?! If not who cares if the temps will only get to 85 next week!?!

Anonymous said...

Love this blog! It's so interesting. I learn more and more about the still emerging science of predicting weather.

This is the type of thing that never gets reported on since it's such a minor system but is just interesting to discover more about.


Anonymous said...

What gets me is the duplicity of how those numbers are calculated.

One forecaster says, "You calculate the relative humidity using the temperature and the dewpoint." (dewpoint of 52 and temp of 80 = rh of 65%)

So you ask, "How do you find the dewpoint?"

"Simple! You just use the dewpoint and the temperature!" (rh of 65 and temp of 80 = dewpoint of 52)

OK. So relative humidity and dewpoint are caclulated numbers. How do you get the MEASUREMENT of humidity in the air?