“Perfect” Fair opener! Irene: Growing threat to New York City?

You can't write it up any better (batter?) than this for the Minnesota State Fair. It's all sunshine on a stick at the Fair today.

Some opening day numbers may be as close to "weather perfection" as it gets!

State Fair Microcast:

63 degrees at 6am Thursday when the Fairgrounds opened

76 degrees at noon (much warmer in the Food Building for lunch)

82 degrees at 4pm (Thursday's day's high temperature at Ye Old Mill)

73 degrees at 10pm (With a brightly lit Midway)

53 degree average dew point Thursday. (Ideal for human comfort!)

5-10 mph west wind (Great food smells wafting on a gentle breeze)

Synopsis:

A clear comfortable late August high pressure will drift right over Minnesota Thursday. Low humidity will bring clear sunny skies. Light west winds will be almost perfect at the Fair, with temps peaking in the low 80s between 2pm and 6pm.

Does it get any better for day 1 of the Fair? Bring the sunscreen!

Looking ahead the first weekend of the Fair looks pretty great. The best chance of T-Storms appears to be late Saturday night into Sunday.

Friday: A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 84. South wind 5 to 9 mph becoming west.

Friday Night: A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 60. North northwest wind between 6 and 8 mph.

Saturday: Mostly sunny, with a high near 78.

Saturday Night: A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 62.

Sunday: A slight chance of showers and thunderstorms. Partly sunny, with a high near 75.

Irene: "Textbook" hurricane now

This is how they teach hurricanes in weather school.

Consider some of Hurricane Irene's features as she ramps up toward likely Category 4 strength Thursday.

-Large (beautiful?) concentric cloud shield with well established outflow

-Clear eye developing

-Concentric central dense overcast (COD) surrounding the eye

-Warm ocean SST's in the mid 80s to feed the growing storm

"Beautiful Monster?"

Irene looks simply beautiful from GOES satellites 22,000 miles above the earth. But she's a monster underneath.

The storm now shows near perfect symmetry. It's a textbook example of how hurricanes form and grow.

Eyewall replacement cycles:

Now that Irene has a distinct eye, look for so called "eyewall replacement cycles" to begin. This process of building-decaying-replacing the eyewall is one way the storm intensifies.

The good news?

The good news is model trends continue to push Irene further to the east. Florida and Georgia, and most of South Carolina are now outside the cone of possible landfall.

The bad news:

North Carolina's Outer banks still may take a direct hit, and it is looking increasingly likely that Irene may pose a threat for a rare direct hit on New York City Sunday night.

The latest model trends bring Irene to near New York City by Sunday night as a Category 1 or 2 hurricane with winds of nearly 100mph.

At this point I would say there is a 50-50 chance that Irene may produce significant damage in New York City. The potential for winds of 100mph, 3-5 foot storm surge into the Hudson River and Lower Manhattan is real.

Rare "Heat Burst" hits southwest Iowa Tueday night:

From NWS Des Moines....a rare heat burst spiked temps 15 to 20 degrees in just a few minutes Tuesday night.

Heat Burst Affects Southwest Iowa

"During the evening of August 23, a rare phenomenon known as a heat burst affected portions of southwest Iowa. A heat burst is characterized by a sudden rise in temperature, a drop in humidity, and strong winds that can approach or exceed severe levels. They are associated with high based decaying thunderstorms with a substantial dry layer beneath the base of the storm. As rain from the thunderstorm falls into the underlying dry air, it cools the air immediately around it, which becomes denser than the surrounding air and begins to sink. As this air sinks, it drys and compresses adiabatically, which results in the hot and dry readings recorded with heat bursts."

Observations

A number of weather stations recorded the heat burst as it passed through. The highest wind gust recorded was 60 mph at the Fontanelle schoolnet site, while both the Atlantic AWOS and Fontanelle schoolnet sites recorded a temperature of 102 degrees. To show just how quckly the weather conditions changed as a result of the heat burst, the tabular data from the Atlantic AWOS is shown below.

Atlantic AWOS Data

Time (CDT) Temp (F)

Dew Point (F)

Wind

5:55pm 84 75 Calm

6:05pm 86 61 16 G 28 mph

6:15pm 93 54 21 G 41 mph

6:25pm 88 61 10 G 39 mph

6:35pm 86 59 12 mph

6:45pm 86 61 14 mph

6:55pm 88 64 16 G 26 mph

7:05pm 90 54 20 G 30 mph

7:15pm 99 18* 8 G 38 mph

7:25pm 102 7* 3 mph

7:35pm 91 52 Calm

7:45pm 88 64 10 G 18 mph

7:55pm 84 72 13 G 21 mph

8:05pm 84 75 8 mph

*AWOS sites typically have problems reporting dew points in low humidity environments, so these two dew point measurements are likely incorrect.

NASA Images: African Dust, Dismal Swamp fires

It's amazing how beautiful our planet is form space. Check out these NASA MODIS Terra images from NASA'a Earth Observatory this week.

Studies have show African dust from the Sahara desert can travel all the way across the Atlantic and end up in the soil in Florida. You can see how that can happen below.

The "Great Dismal Swamp" (sounds like a great vacation destination huh?) in Virginia is a strange place, and this year it's on fire. Check out the smoke plume form space.

Just a little reminder how very small we are in a really big world.

Enjoy our fine late August weather pattern, and open those windows for "good sleeping weather" the next few nights!

PH