Here is an update concerning Tropical Storm Bertha:
Changes from previous update:
- The forecast intensity has increased to 60 mph from the previous advisory before shear likely impacts it more and starts to weaken Bertha before landfall
Overview:
- Bertha is forecast to continue to drift/meander northwest through today before finally turning more to the west as high pressure builds north of it.
- Despite the pressure falling to 998mb and max sustained winds increasing to 50 mph Bertha continues to struggle to get organized due to shear it is already dealing with along with drier air around it.
- No changes to the Tropical Storm and Storm Surge Watches and Warnings from the previous advisory.
- The storm will not have any significant impacts on the area through today, but it is forecast to bring minor to moderate storm surge flooding, strong/gusty winds, and some potential for locally heavy rainfall to portions of the area Wednesday through Thursday morning – with the greatest impacts across immediate coastal areas.
- This storm is forecast to be very lopsided with most of the rain/strong winds/etc on the southern side of the storm. This should keep the greatest impact across the Gulf, but will also mean that if the storm tracks farther north, some of the more impactful weather will move onshore.
Confidence:
- If the current forecast holds, we are confident that minor to moderate impacts will be experienced across the local area.
- However, there is still lower than normal confidence in the intensity forecast and there could still be adjustments to the forecast impacts while the system continues to organize.
Impacts: The following impacts will be possible mainly Wednesday through Thursday morning:
- Storm Surge: Minor to moderate storm surge flooding with up to 2-4ft of flooding above ground for immediate coastal areas east of the MS River. 1-3ft of flooding above ground elsewhere along the coast. Low lying coastal roads may become impassable Some non-elevated structures and under-home storage areas may become flooded in areas where the highest storm surge occurs. Minor to moderate beach erosion will be possible. Some damage to marinas, docks, and piers will also be possible.
- Wind: Tropical storm winds, especially in the form of gusts, are likely with the greatest threat of sustained tropical storm winds along the immediate coast. Lightweight and unsecured outdoor items could be blown around (trashcans, etc). Damage to a few porches, awnings, sheds, etc will be possible. Tree limbs could be downed in some areas, leading to isolated power outages.
- Rainfall; The rainfall forecast and impacts will be HIGHLY dependent on the eventual track of Bertha and whether any significant rain wraps around the northern side of the storm. The heaviest rain will be on the south side of the storm, which means many areas will see less than an inch of rain from this system. However, there is *potential* for 2-4″ of rain mainly in coastal portions of SE LA. Keep in mind that high rainfall rates even in isolated to scattered storms could result in localized flooding.
- Tornadoes: Tornadoes currently appear unlikely (mostly due to the fact that the majority of the storms are expected to remain over the water); however, there is a non-zero risk for one or two tornadoes Tuesday afternoon mainly over southwestern portions of the outlook area.
- Heat; Even though this is not a Tropical Impact, this is a current and likely continuing impact to the region through Bertha’s evolution. Dangerous heat conditions are tomorrow with heat index values of 107-111 across the local area. Due to the lopsided nature of the storm, if there isn’t much cloud cover or rain on the north side, dangerous heat conditions could persist into Wednesday and Thursday even as the center of Bertha moves near or across the area.