SUMMARY OF 400 PM CDT
LOCATION…22.1N 89.5W
ABOUT 55 MI…90 KM NNE OF PROGRESO MEXICO
ABOUT 580 MI…935 KM SSE OF CAMERON LOUISIANA
MAXIMUM SUSTAINED WINDS…85 MPH…140 KM/H
PRESENT MOVEMENT…NW OR 305 DEGREES AT 17 MPH…28 KM/H
MINIMUM CENTRAL PRESSURE…977 MB…28.85 INCHES
FORECAST POSITIONS AND MAX WINDS
INIT 07/2100Z 22.1N 89.5W 75 KT 85 MPH
12H 08/0600Z 23.2N 91.2W 85 KT 100 MPH
24H 08/1800Z 24.8N 92.9W 95 KT 110 MPH
36H 09/0600Z 26.7N 93.4W 100 KT 115 MPH
48H 09/1800Z 29.1N 92.9W 90 KT 105 MPH
60H 10/0600Z 31.6N 91.9W 45 KT 50 MPH…INLAND
72H 10/1800Z 33.7N 90.5W 30 KT 35 MPH…INLAND
96H 11/1800Z 37.0N 85.5W 20 KT 25 MPH…POST-TROP/REMNT LOW
120H 12/1800Z…DISSIPATED
KEY MESSAGES
1. Winds and water levels along the northern coast of the Yucatan Peninsula will gradually subside this evening. Heavy rainfall, which could lead to significant flash flooding, will affect the
northern Yucatan Peninsula through early Thursday.
2. Delta is expected to grow in size as it approaches the northern Gulf Coast, where life-threatening storm surge and dangerous hurricane-force winds are likely beginning Friday, particularly for portions of the Louisiana coast. Storm Surge and Hurricane Watches are in effect, and residents in these areas should follow advice given by local officials.
3. Flash, urban, small stream and minor to isolated moderate river flooding is likely Friday and Saturday from portions of the central Gulf Coast into portions of the Lower to Middle Mississippi Valley. As Delta moves farther inland, additional heavy rainfall is expected in the Ohio Valley and Mid Atlantic this weekend.
OUTLOOK
At 400 PM CDT (2100 UTC), the center of Hurricane Delta was located near latitude 22.1 North, longitude 89.5 West. Delta is moving toward the northwest near 17 mph (28 km/h). A northwestward motion with a reduction in forward speed is expected through early Thursday. A north-northwestward motion is expected by late Thursday, and a faster northward to north-northeastward motion is
forecast on Friday and Friday night. On the forecast track, the center of Delta will move over the southern and central Gulf of Mexico through Thursday, and approach the northern Gulf coast within
the hurricane watch area on Friday. Delta is forecast to move inland within the hurricane watch area by late Friday or Friday night.
Data from an Air Force Reserve Hurricane Hunter aircraft indicate that the maximum sustained winds are near 85 mph (140 km/h) with higher gusts. Re-strengthening is forecast when the hurricane moves
over the southern and central Gulf of Mexico through Thursday, and Delta is expected to become a major hurricane again. Some weakening is is forecast as Delta approaches the northern Gulf coast on
Friday.
Hurricane-force winds extend outward up to 35 miles (55 km) from the center and tropical-storm-force winds extend outward up to 125 miles (205 km).
The latest minimum central pressure estimated from Air Force Reserve reconnaissance aircraft data is 977 mb (28.85 inches).
HAZARDS AFFECTING LAND
STORM SURGE: Water levels along the northern coast of the Yucatan peninsula will gradually subside this evening.
The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide…
Pecan Island, LA to Port Fourchon, LA including Vermilion Bay…7-11 ft
Cameron, LA to Pecan Island, LA…4-7 ft
Port Fourchon, LA to Ocean Springs, MS including Lake
Borgne…4-6 ft
Lake Pontchartrain and Lake Maurepas…3-5 ft
Ocean Springs, MS to AL/FL border including Mobile Bay…2-4 ft
High Island, TX to Cameron, LA including Calcasieu Lake…2-4 ft
Sabine Lake…1-3 ft
Port O’Connor, TX to High Island, TX including Galveston Bay…1-3 ft
The deepest water will occur along the immediate coast near and to the east of the landfall location, where the surge will be accompanied by large and dangerous waves. Surge-related flooding
depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.
WIND: Hurricane and tropical storm conditions will continue within portions of the warning area in the Yucatan peninsula during the next few hours. Tropical storm conditions are possible within the
watch areas along the Gulf coast by late Thursday night or early Friday with hurricane conditions possible within the hurricane watch area by Friday.
RAINFALL: Through early Thursday, Delta is expected to produce 4 to 6 inches of rain, with isolated maximum totals of 10 inches, across portions of the northern Yucatan Peninsula. This rainfall may result in areas of significant flash flooding.
Friday through Saturday, Delta is expected to produce 4 to 8 inches of rain, with isolated maximum totals of 12 inches across portions of the central Gulf Coast north into portions of the Lower to Middle Mississippi Valley. These rainfall amounts will lead to flash, urban, small stream and minor to isolated moderate river flooding. As Delta moves farther inland, 1 to 3 inches of rain, with locally higher amounts, is expected in the Ohio Valley and Mid Atlantic this weekend.
TORNADOES: The risk of a few tornadoes will increase late Thursday night into Friday over portions of southern Louisiana, southern Mississippi, and southwest Alabama.
SURF: Swells from Delta will begin to affect portions of the northern and western Gulf coast on Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please
consult products from your local weather office.
TECHNICAL DISCUSSION
The center of Delta has moved off the northern coast of the Yucatan peninsula and is now located over the southern Gulf of Mexico. The hurricane remains well organized in satellite imagery with a large curved band wrapping around the center and a fairly symmetric CDO. An Air Force Reserve reconnaissance aircraft has provided a few center fixes this afternoon, and found that Delta’s passage over land has resulted in weakening, and the initial wind speed is set at 75 kt, which is based on a peak flight-level wind of 81 kt. The aircraft also reported a minimum pressure of 977 mb on its final center penetration, and data from the plane indicate that there has been some increase in the radius of maximum winds.
Re-strengthening is anticipated over the next 24-36 hours while Delta moves within a favorable upper-level environment and over the relatively deep warm waters of the southern and central Gulf of
Mexico. Most of the intensity guidance brings Delta back up to major hurricane status, and so does the official forecast. The global models also significantly deepen Delta during the next 36
hours, lending confidence to re-intensification. After 36 hours, increasing shear and cooler waters over the northern Gulf of Mexico are likely to cause some decrease in intensity before Delta makes
landfall, however the hurricane’s wind field is forecast to expand, which will increase the storm surge and wind threats. Regardless of Delta’s landfall intensity, life-threatening storm surge and strong winds are likely over a large portion of the northwestern and northern Gulf coast.
Delta has been moving on a consistent northwestward heading of 305 degrees at about 15 kt. Delta should continue on this general heading with some reduction in forward speed tonight and early
Thursday as it approaches the western extent of the subtropical ridge. A mid- to upper-level trough over Texas is forecast to slide eastward over the next couple of days, which is expected to cause Delta to turn north-northwestward on Thursday, and northward toward the northern Gulf coast by Friday. A faster northward to north-northeastward motion in 48-60 hours will bring the center onshore along the northern Gulf coast late Friday. The cross track spread in the dynamical models has decreased this cycle, with the model predictions converging on the previous NHC track forecast.
Therefore, little change has been made to the previous official forecast, and it lies near the center of the now tightly clustered guidance envelope.
