Thursday, May 22, 2014

Mainly Dry through Memorial Day Weekend

By Jay Grymes & Steve Caparotta

WAFB Storm Team QuickCast:

- staying mainly-dry through Monday
- flirting with highs around 90° over the next four days
- finally a chance of rain by the middle of next week

The daily forecast for the Capital City is getting awfully repetitive: morning starts in the mid to upper 60°s with some patchy fog, afternoons in the upper 80°s to near 90° under fair to partly cloudy skies, and not a drop of rain falling anywhere for hundreds of miles!

And there’s no real change to the daily outlook through the Memorial Day weekend. That’s good news for the festivals, fun and outdoor memorials that will be on-going through the holiday, but it’s getting very, very dry across the viewing area with no immediate relief in sight -- unless you’re doing the watering yourself!

We’ve mentioned this before: around this time of year, most of our outdoor environments -- both the natural and the ‘landscaped’ -- prefer about an inch of water or more per week, especially given the plentiful sunshine we’ve seen the last several days. But for most of us, the last significant rain was ten or more days ago.

We’re still a long way from “drought” right now, but a prolonged run of more days like the last several would push the area toward drought quickly. Thankfully, our extended outlook offers some relief by the middle of next week. Here’s hoping that pans out.

In the meantime, maybe today’s most anticipated weather story was the NOAA official tropical outlook for the 2014 Hurricane Season. With most models suggesting the onset of an El Niño in the coming months, plus a forecast for near-normal sea-surface temperatures (SSTs) across the tropical Atlantic this season, the NOAA tropical outlook team of experts are claiming a 90% likelihood for a near-normal to below-normal tropical season this year (in terms of storm numbers). Their forecast calls for a 70% chance of only 8 to 13 named storms this season.

El Niño -- characterized by warmer-than-normal SSTs over the central and eastern equatorial Pacific -- is associated with a seasonal increase mid-level wind shear over the tropical Atlantic Basin. More mid-level shear over the Atlantic means a more hostile atmosphere for tropical systems to form and develop. At the same time, the anticipated near-normal SSTs over the tropical Atlantic this season would be a departure from recent years, when Atlantic SSTs have tended to be above normal. As warm water is the source for most of a tropical system’s energy, lower SSTs are presumed to mean a slight reduction in available storm energy for developing systems. Taken together, the NOAA experts -- and most of the private-sector tropical forecasters as well -- see these two factors as key in assessing a lower storm count for the coming season compared to most of our recent years.

However, reduced storm numbers do not directly translate into a reduced threat. Three history-makers for the Bayou State -- Audrey (1957), Betsy (1965) and Andrew (1992) -- all developed during, or in the waning months, of past El Niño periods. Steve Caparotta will take a closer look at the details of El Niño’s role in Atlantic tropical activity in our coming Hurricane Special, “The 5th Season” -- slated for airing on June 2nd!

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