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Thursday, October 1, 2015

Joaquin's Journey

The third hurricane of the 2015 has become the strongest. Today, Joaquin was found to be packing 130 mph winds, making it a dangerous category 4 hurricane. Very warm water and weak upper-level steering conditions are creating the perfect environment for growth. Residents in the southern Bahamas are reporting widespread flooding and wind damage Thursday afternoon. So the question now is, where will Joaquin head next? Here's the latest forecast from the National Hurricane Center:

It still shows the storm remaining just off shore and not making landfall. For the past few days, models that forecast movement have been waffling between sending the storm out to sea and taking aim at some point of the east coast. Not surprisingly, the official track from the National Hurricane Center has been quite wide, nearly paralleling the east coast. This is intended to demonstrate the uncertainty of the forecast.

There are two major complicating factors steering this storm. The first is a stalled cold front, which is draped along the east coast. This has brought some heavy flooding rains from parts of Maine down to South Carolina:

At the same time, there is an upper-level low pressure cell in the southeast that may draw Joaquin northward over the weekend as well as enhance moist conditions from the mid-Atlantic to the southeast:

Computer projections have varied because the location and strength of the upper-low in the Southeast is uncertain. It seems that each day's computer model runs makes a different determination of where the upper-level low will end up.

This afternoon, the so-called spaghetti model plots have a split decision, with roughly half of them trending toward a mid-Atlantic landfall by Sunday and the other half sending the storm toward Bermuda:

There is virtually no chance of Joaquin heading into the Gulf of Mexico, so this will largely be an East Coast concern. It is also interesting to note that in the last 10 years, there have been fourteen Category Four hurricanes, most of them occurring in late September or October. Most have impacted the Caribbean or meandered in the middle of the Atlantic. The last Category Four hurricane to hit the U.S. was Charley in 2004.

Continue to watch for my blog updates on this dangerous storm to see where it ends up. If you know folks along the East Coast, encourage them to remain watchful and to be prepared. Even if the hurricane doesn't make a landfall, the stalled out front could bring more heavy rain that may lead to flooding.

Monday, September 14, 2015

Showers Make A Comeback

Keep the umbrella handy Tuesday as a weak disturbance in the Gulf sends showers toward the upper-Texas coast. The last few days featuring warm, but not overly humid weather, and pleasant mornings is about to change.

High pressure in the Southeast U.S. will allow for southeast winds to develop, which always means a return of muggy weather to Houston. Additionally, there are signs of low pressure in the western Gulf of Mexico.

Typically, a low in the Gulf might raise a few eyebrows, even though we've reached the peak of hurricane season. However, the low is very weak and very disorganized. Also, there isn't high pressure aloft. The latter would make tropical development a bit more favorable.

Expect showers today to develop as those southeast winds send Gulf showers inland. The afternoon could be especially soggy and even in the morning, there may be considerable cloudiness. 

Once Tuesday's rain threat diminishes, the rest of the week looks rain free, although the southeast winds will make the days warm and muggy and the mornings not quite as pleasant as they have been recently. Lows should range in the mid to upper 60s.

Tuesday, September 8, 2015

Change On The Horizon

No sign of summer's end today as the heat beat wears on across the Lone Star. Nothing really unusual about that after Labor Day. However, there are signs of change later in the week. It is very likely that a cold front, currently dragging through the middle of the country is headed toward Texas.

Along the front, showers and in some cases, stronger thunderstorms are likely to develop. The front should make it through Dallas by Wednesday and then arrives along the Upper Texas coast by Thursday. Here is a projection for rain and the front then:

The slow-moving nature of this front means rain chances could linger well into the weekend. It's still a little early for THE cold front that puts and end to the seemingly endless summer, but it will be a welcome sign.

Tuesday, September 1, 2015

Soggy Start To September

Even though rainfall in August was .66" below normal, there were only five days with rain in Houston. So the forecast for wet weather over the next few days is a good thing. The image above shows the water vapor imagery for Texas. The bright white indicates moisture, the red area indicates dry sections. 

An upper-level disturbance near Corpus drifts slowly northward, spreading rain chances upward and inward today and tomorrow. With little steering it, showers could linger through late in the week. Here are projections for Tuesday and Wednesday:

There are no concerns as of yet for flash flooding as there should be decent breaks between rainfall episodes. Best advice: keep the rain gear handy.

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!