Imelda rain threat largely west, tropical Atlantic is busy
The local area is caught between tropical moisture to the southwest and dry air to the northeast. This makes the forecast a bit tricky, creating a significant difference in rain chances from the coastal parishes to southwest Mississippi.
On Tuesday, the forecast called for isolated showers and thunderstorms, generally west of the Amite River with the possibility of downpours and gusty wind. Indeed, storms produced some brief heavy rain but the most attention-getting storm of the day led to a few planes being flipped at Metro Airport in Baton Rouge. 60-70mph wind gusts occurred as dry air from the northeast was pulled into the tropical thunderstorms associated with Imelda. Dry air rapidly cools the storm cloud and because cold air is heavier than warm air, it rapidly falls to the surface causing gusty wind.
Today and Tonight: Not much change is expected for Wednesday although the chance for isolated showers and thunderstorms may nudge just a bit farther west. Thanks to the tropical nature of the showers, brief downpours could lead to some nuisance street and poor drainage flooding. Frequent lightning and gusty wind could also accompany any storms. Prior to any clouds and rain, some sun and warm temperatures are expected. Highs will be near 93 with lows near 75.
Up Next: A weak front will push into the area on Thursday. This boundary will likely kick out isolated to scattered showers and thunderstorms. Due to the relatively drier air mass aloft, some of the storms could produce gusty wind. Unfortunately, the front is not expected to bring major changes to temperatures or humidity with numbers only going down a few clicks for Friday and the weekend. The long-term outlook from the Climate Prediction Center holds above average temperatures through the end of the month. In fact, the Baton Rouge area is on pace for its hottest September on record.
The Tropics: The Atlantic Basin is rather busy. The remnants of Tropical Storm Imelda will bring 7-10 inches of rain to southeastern Texas over the next few days. Hurricane Humberto has become a major hurricane, racing out to sea but expected to clip Bermuda along the way. Gusty wind, 2-4 inches of rain and 2-4 feet of storm surge are expected Wednesday and Thursday. Tropical Storm Jerry formed overnight and will become a hurricane as it approaches the Lesser Antilles this weekend. At the moment, a turn to the north is expected to occur next week, but it is too early to rule out impacts to the United States. Two other waves, one near the Cabo Verde Islands and another near the Windward Islands, are given a 20 percent chance of formation over the next 5 days.
As Imelda moves across Texas on Wednesday, drier air will remain steadfast across the Mid-South. A battleground between these two air masses is set across the local area making for a tricky rain coverage forecast. The best bet for rain on Wednesday will be closer to that deeper tropical moisture in the western half of the 13 Parish, 3 County forecast area. Much heavier action is anticipated into southeast Texas where there is a “high risk” for excessive rainfall today. As the remnants slide farther northwest into Texas, a weak cold front may move into the area by late Thursday. This front is not expected to modify temperatures or dew points much, but it may be able to stir up some showers and thunderstorms Thursday and Friday. Any rain would be beneficial to the area, but thunderstorms will be capable of producing gusty wind due to the continued presence of dry air in the middle of the atmosphere. Generally, dry and warm conditions will prevail through the weekend into early next week. While the end of September is a time we start to see some fronts making it into the region, there is no immediate sign of a significant passage and the Climate Prediction Center is calling for above average temperatures and drier conditions to end the month.
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