Hot & Dry Sunday - Wednesday

While everyone seems focused on Erin, the local weather news is that after scattered showers tomorrow and Saturday, few showers will be around starting on Sunday. Upper air conditions should put a lid on the atmosphere. That’s not what you want to see in mid-August if you garden.

For what little can be said of the local forecast, skip ahead to “At-A-Glance” and Forecast Discussion. For Erin and future tropical speculation, it’s “Long-Range Ramblings”. But for the meteorologically curious, what in the world happened with that amazing fireworks show last night? Why did thunderstorms light up the sky from 9:30 PM to midnight?

In order to get lightning, you need cumulonimbus cloud tops to be well below freezing so the rain drops can turn to ice crystals or soft hail. That gives you the charge separation needed. Surprisingly, many tropical clouds which give you downpours don’t get to heights where the temperatures are much below freezing. Last night’s did because an upper air trough helped the air to rise higher and also dropped the temperatures a few degrees up where they jets fly. Because the system was driven more by upper air cooling an instability rather than surface heating, it persisted well past my bed time (Yawn). Too bad that the trough was so subtle that forecasters didn’t see it.

The Foreca graphic makes it look like it will rain everyday, which I doubt, but the amounts are piddly. I think tomorrow, Friday, will feature a few scattered storms anytime from mid-day to evening with the greatest chance happening along or near I-10 in Mississippi (the Buccee’s effect). Saturday could go either way — a dry, hot one, or one with 40% scattered afternoon storms. A one degree difference of temperature at 10,000 ft. will shift it either way. High temperatures generally low 90s.

After that, an upper air high pressure system with warmer air aloft will suppress most showers through Wednesday. The Foreca graphic doesn’t really capture this. I see highs 92-95. After that, back into a more showery regime.

Tropical Storm Erin is strengthening, but the dense overcast shown on the satellite image is not perfectly round indicating that it is fighting some shear. The further west it will go, the more favorable conditions it will encounter. Erin should become a hurricane later tomorrow and a major one a day or two after that.

Though there’s a lot of hype about the track shifting, all of the models show it going a few hundred miles north of the Virgin Islands and Puerto Rico and none of the models show it making U.S. landfall. Sure, I wouldn’t want to be snorkeling on the north side of St. John on Saturday or surfing off the Outer Banks next Wednesday, but other than that, I’m not seeing significant U.S. impacts. Here’s the latest NHC plot with my extreme east-side and west-side paths beyond the 5-day cone.

A feature closer to home is the cloud swirl in the SW Gulf that is making steady progress as it heads NWtowards the Mexican coast just south of Brownsville. It will probably be called a depression, NHC rates this as having a 40% of becoming a tropical storm and it will dump rain on many ripening Ruby Red grapefruit in the Rio Grande. There’s no chance of this heading in our direction.

Models are showing something coming behind Erin that will be near the Dominican Republic a week from Saturday, August 23. That certainly bears watching, but it’s too early to say anything..

Foreca graphic for Pensacola Beach shows much better weather than the last few weeks with highs near 90 or in the low 90s, light winds, and a chance of showers Sunday night through Tuesday.