Tuesday, July 6, 2010

Two tropical systems...heavy rain threat through Friday

Here we go again....we are currently watching two tropical systems that will have an impact on southeast Texas this week. The first is a well defined tropical low that moved inland across south-central Louisiana yesterday, producing flash flooding and is moving toward southeast Texas; the other is a strong tropical wave over the Yucatan peninsula that is forecast to head toward the lower to middle Texas coast by Thursday. All in all, these two systems will once again bring in some very deep tropical moisture out of the gulf and give us another threat for heavy rain.

LA System:
The small area of low pressure that moved inland in south-central LA yesterday is now located to the northeast of the Lake Charles area and is starting to take on more semi-tropical characteristics. As this low moves west, very deep tropical moisture, marked by precip water values in the 2.4-2.6'' range will spread into southeast Texas from east to west this afternoon and evening. Current thinking is that we will see scattered shower and thunderstorm activity on the west side of the low this afternoon before things transition over to more of a nocturne core rain event overnight tonight. Right now, it looks as if areas east of I-45 will have the greatest likelihood of seeing these core rains. Tomorrow, the surface low will be off to the northwest of the region allowing for a deep moisture tap to setup across the area. Expect widespread showers and thunderstorms to develop with heavy rain. With the moist ground conditions, the flooding threat will be high, especially in areas of poor drainage.

Invest 96L currently impacting the Yucatan peninsula and is forecast to move off into the southern Gulf of Mexico over the next 24 hours. At this time the system is not showing any signs of significant organization in the shower and thunderstorm activity and therefore the NHC has given the system about a 30 percent chance of development. The latest models have backed down on trying to develop a well defined low with the system, although upper level winds will be favorable for the development so this will need to be watched closely over the next few days. Will be watching for several scenarios to possibly play out as far as the rainfall threat is concerned. Models indicate that the tropical wave, or possible surface reflection should reach the middle-Texas coast Thursday with a significant amount of moisture advection on the northeast side of the system. Therefore, they really hammer the middle to upper Texas coast and southeast Texas with a significant amount rain late Wednesday and Thursday. If the system manages to close off into a low, then the heaviest rains could be focused closer to where the center crosses the coastline...which would be more toward the middle-lower Texas coast. Needless to say, there is still a good bit of uncertainty as to how this system will impact the region; therefore it will be important to monitor the latest forecasts over the next few days concerning the development of the system.

Look for additional updates throughout the week concerning the tropical and heavy rainfall threats to the region.

Friday, July 2, 2010

Heavy Rain Threat Continues

Heavy rain has plagued portions of southeast Texas since the landfall of Hurricane Alex two days ago. Very deep tropical moisture remains in place across the region with extremely high precip water values in the 2.6-2.8'' range. The boundary that plagued western Brazoria and Matagorday counties yesterday dropping 6-10'' of rain is slowly starting to move inland and is edging closer to metro Houston this morning. Scattered showers and thunderstorms continue to develop along this boundary and move northwest. We are going to have to keep a very close eye on the training situation today as the boundary moves into the city as flash flooding could become a problem. Heavy rain will remain the main weather threat into tomorrow across southeast Texas.

Storm Total Precip through 6:30am