Good afternoon all,
Jeff Lindner’s afternoon update – Feel free to share with your industry members as warranted.
HCOHSEM is continuing to monitor Hurricane Delta at Level III, Increased Readiness, with HCOHSEM staff only. Based on the current forecasted track and impact, we do not see a need for an industry brief webinar at this time. If conditions change such that the storm might impact Harris County, we’ll schedule an industry Zoom meeting to discuss the details of potential impacts.
Sent by Pamela Parker, EHCMA, on behalf of:
Harris County Office of Homeland Security & Emergency Management
From: Lindner, Jeffrey (Flood Control)
Sent: Thursday, October 8, 2020 4:05 PM
Subject: Delta (Thurs PM)
Large and dangerous hurricane Delta moving toward the NW Gulf of Mexico.
Delta becomes a category 3 hurricane with winds of 115mph
Tropical Storm Warning is extended west to Sargent TX
Hurricane Warning is in effect from High Island to Morgan City
Storm surge warning is extended west to High Island
Delta has continue to organized today with an eye finally starting to show up on both visible and IR satellite images. Most recent USAF mission pass through the center recorded a central pressure down from 968mb to 954mb and flight level winds of 110-120kts in the NE eyewall. Dropsonde data in the SW eyewall recorded winds near the surface of 110kts (125mph) The overall structure of the hurricane continues to improve and Delta will likely continue to intensify through the night. Delta is moving toward the NW around 15mph and should begin to turn toward the NNW and N tonight.
Tropical storm force winds extend outward 160 miles from the center and hurricane force winds 35 miles from the center
There has been no changes in the track forecast and Delta is moving along the forecasted track as expected. Along this track, Delta should make landfall over SW Louisiana Friday afternoon and evening. Due to the expected expansion of the wind field, TS warnings have been extended westward along the TX coast.
As mentioned the overall structure of Delta continues to improve with an eye appearing in satellite images and dual outflow channels to the north and the south helping to move rising air near the center of the hurricane outward. Conditions are near ideal for intensification through tonight, but as Delta moves northward over the western Gulf on Friday upper level winds will be increasing from the SW due to a trough over TX and sea surface temperatures will be decreasing as Delta nears the US coast. Both of these factors will likely lead to some degree of weakening, but exactly how much is in question and the point should be clear that regardless of weakening Delta will be a large and significant hurricane at landfall over SW Louisiana
- Tides and seas will begin to increase today and peak on Friday as Delta moves into the NW Gulf. Water levels along the upper TX coast are expected to reach 1-3 feet above normally dry ground which will be similar to hurricane Hanna and hurricane Laura. At times of high tide some coastal flooding will be possible on Bolivar, the west end of Galveston, Surfside, Sargent, and the west side of Galveston Bay. Additionally wave run-up along the coast could result in locally higher values. Late Friday as winds become NNW and NW over Galveston Bay, this will drive water in the Bay southward and toward the north sides of Galveston and Bolivar which may result in some backside flooding in those areas.
- Rainfall will generally average less than 2 inches east of I-45 in some outer squalls on the west side of Delta. There may be some interaction with the trough over central TX and the western side of the circulation of Delta that may result in some enhancement of rainfall a bit further inland on Friday.
- Tropical storm force winds will be possible in the TS warning area, although this will be heavily dependent on the expansion of the wind field and Chambers and southern Liberty Counties have the greater risk of sustained tropical storm force winds. Could see sustained tropical storm force winds in and around Galveston Bay on Friday and over southeast Harris, Galveston, and coastal Brazoria Counties.
- Life threatening storm surge of 7-11 feet above the ground now likely over SC LA from where the center makes landfall east toward the Grand Isle and Port Fourchon areas including Vermillion Bay. In areas around Vermillion Bay this level of storm surge would be about 5-6 feet higher than that observed with hurricane Laura. Values between Cameron and Pecan Island which were heavily impacted by Laura are forecast to be between 4-7 feet including Grand Chenier and Creole. It should be noted that storm surge may extend well inland over the flat marsh lands of southern Louisiana and those locations that are not directly on the coast, could still experience significant storm surge impacts.
- Rainfall will generally be 6-10 inches along the track of the hurricane and due to the fast forward motion, widespread significant flooding is no expected.
- Tropical storm and hurricane force winds will impact a large area of SW and SC LA including those areas recently impacted by hurricane Laura. Due to the fast forward motion, strong winds will extend well inland along the track of Delta including the Abbeville, Lafayette, New Iberia, and Crowley areas.