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Thursday, August 27, 2015

Erika Emerges As A Potential Threat

Tropical Storm Erika drenched and damaged parts of the Leeward Islands Thursday with Puerto Rico and Hispanola in its sights for Friday. Unlike its predecessor Danny, which barely brought much rain to the Caribbean earlier this week, Erika may make more of an impact.

Already four lives were lost in Dominica as torrential rain sparked mudslides and several homes and buildings were damaged. Even though the storm only has 45 mph winds, weak construction often leads to quicken ruin.

The latest track from the National Hurricane Center has Erika becoming a Category 1 hurricane threatening the Florida peninsula early next week:

Danny was no match for a strong shear zone as it approached the eastern Caribbean. That storm was torn apart by the stronger winds aloft. Erika is moving into a somewhat weaker shear zone, which should slow its growth. However, it will still likely bring some substantial rains to drought-stricken Puerto Rico.

Once Erika crosses Hispanola, things get more interesting as there is less shear and water temperatures are extremely warm. Take a look at the pool of water warmer than 30° C (85° F) degrees in the Bahamas, eastern Gulf and around Florida's Atlantic coast:

As Erika emerges from Haiti and the Dominican Republic this weekend, it could experience explosive growth as it moves over that water. The majority of computer models have the storm heading toward Florida with only a few keeping it away from the U.S. and a handful nudging it into the Gulf:

One of the challenges for this storm is that once it moves toward the Bahamas, there isn't much in the way of upper-level winds to steer it. Based on the so-called spaghetti plots of the various computer models, Erika could linger off the Georgia and South Carolina coasts for several days. 

It's not quite deja vu as the 10 year anniversary of Katrina's landfall approaches this weekend, but it doesn't help allay fears. If indeed Erika does become a hurricane and strikes Florida, it would be the first time in ten years that the Sunshine State has been hit by a hurricane. The last one was Wilma in 2005.

As with all storms, this one needs to be monitored as it continues to move and develop and forecasts change (and they will). As I am fond of saying - stay tuned...and be prepared.

Tuesday, August 18, 2015

Talking Tropics - Danny...and more?

Circled above is the fourth named storm of the 2015 season, Danny. It began as a wave emerging off the west coast of Africa late Sunday. Current projections show Danny will continue moving westward in the Atlantic and likely strengthen. Here is the current forecast track from the National Hurricane Center:

Of course, a lot can and will happen over the next five days. Danny is close to the equator and relatively warm Atlantic water. Those factor contribute to growth. However, as it approaches the eastern edge of the Caribbean, it may run into enough shear to disrupt it.
Here is a depiction of shear by early week:

Currently, long-range models show this shear stopping any more of Danny's (indicated by the red "L") westward progress. Check back here later in the week to see how things develop.

In the meantime, on the 32nd anniversary of Hurricane Alicia's arrival in Houston, I noticed this blob of clouds in the western Gulf:

The extremely warm water and high pressure aloft make for a good environment for growth, however, the approaching cool front should nudge this mass of clouds into the Gulf. It is curious, however, that as of this writing, none of the computer models have seemed to pick up on this feature.

Again, stay tuned as we continue to lurch toward the heart of the season. 

Friday, August 7, 2015

Record-Breaking Heat On The Way

Forecast temperatures over the next week.

The triple-digit drumbeat isn't anything too unusual for the Bayou City in the summer. However, this round of high heat will break records and possibly set a new all-time record.

Depicted above is the temperature forecast from various computer models. Note the white line which represents the model average. It approaches 105° could even go higher. In fact, it is possible that the highest ever mark of 109° set memorably on August 27, 2011, could be challenged. During that month in 2011, all but one day registered 100° or higher.

Here are the forecast temperatures and records for the up-coming misery:

                     Forecast             Record
Aug 7               102°                  104° (2003)
Aug 8               102°                  104° (1962)
Aug 9               103°                  106° (1962)
Aug 10             106°                  104° (1962)
Aug 11             106°                  102° (2011)
Aug 12             105°                  105° (1962)

Additionally, there will be enough humidity to push the heat index over 110°.  This is a depiction of the forecast for how hot it will feel. It is a reminder to be sure you exercise caution when outside, especially keep the young ones in and check in on elderly neighbors. 

Whenever southeast Texas roasts like this, it's because a ridge of high pressure is parked over the state. Under the ridge, the air is sinking and compressed, leading to 100° days. Here is the upper-level wind pattern depicted centered firmly over southeast Texas by late Sunday:

The ridge won't break down appreciably until the end of next week. As it shifts to the west, a slight chance of isolated showers could return. Ah...summer in H-town!