Hurricane Sally Advisory 13 Date: Monday, September 14, 2020 2:41:33 PM

From: StormGeo To: Lindsey Falconer Subject: Hurricane Sally Advisory 13 Date: Monday, September 14, 2020 2:41:33 PM

Hurricane Sally Advisory 13 Valid: 03:00 PM CDT Monday September 14, 2020

Current Location: 28.8N, 87.3W Geographic Reference: 145 miles Southeast of Biloxi, Mississippi Movement: West-northwest at 6 mph Max Winds: 90 mph gusting to 110 mph Current Hurricane Severity Index: 10 out of a possible 50 points (3 size, 7 intensity) Max Predicted Hurricane Severity Index: 15 out of a possible 50 points (5 size, 10 intensity) Current Radius of Tropical Storm-Force Winds: 125 miles Max Predicted Radius of Tropical Storm-Force Winds: 125 miles Organizational Trend: Steady Forecast Confidence: Average Estimated Central Pressure: 986 mb

Key Points 1. We have adjusted the track slightly to the east and have increased the intensity forecast. 2. Landfall is forecast to occur over coastal Mississippi by early Wednesday morning with maximum winds of 100 mph winds. 3. Flooding from heavy rainfall remains the greatest threat to the Gulf Coast.

Our Forecast It appears that the intensity of Sally has leveled off over the past few hours. We have increased the intensity forecast in this update based on the latest reconnaissance data and model trends. Sally will strengthen through Tuesday as it moves to the west-northwest towards the southeast Louisiana coast and decelerates. Afterward, Sally will turn to the north to north-northeast and move towards the Mississippi Coast Tuesday afternoon and evening. The track was adjusted slightly to the east in this update. We think that landfall will occur early Wednesday morning just east of Biloxi. Afterward, Sally will move inland with an increasing forward speed.

As Sally is expected to be moving very slowly at landfall, there will be a prolonged period of high winds and tidal surges. In addition, there will be a prolonged period of heavy rainfall. Areas of southern Mississippi and Alabama could receive the most rainfall from Sally with some locations receiving more than a foot of rainfall.

Expected Impacts On Land Gulf Coast: Conditions will deteriorate into tonight from east to west across the north- central Gulf coast as rain bands begin to move in. Widespread power outages are likely. Wind and tidal surge damage will be possible, especially along the Mississippi and Alabama coast. Widespread flooding due to the heavy rainfall is also expected. Significant flood damage from heavy rainfall is likely for southern Mississippi and Alabama.

Expected Impacts Offshore Winds of tropical storm force are occurring now for the lease blocks off of Alabama, Mississippi, and Louisiana. Conditions will continue to deteriorate through this evening. Conditions are not expected to improve until Wednesday after Sally moves inland.

The next advisory will be issued by 9 PM CDT.

Meteorologist: Claude Aultman

Hurricane Severity Forecast Confidence: Average Index Max Fcst Max Valid Lat. Lon. Sustained Category Size Intensity Total Hour Gusts Winds 3PM CDT 110 0 28.80N 87.30W 90 mph Category 1 3 7 10 Mon Sep 14 mph 3AM CDT 125 12 29.10N 88.40W 105 mph Category 2 5 9 14 Tue Sep 15 mph 9AM CDT 130 18 29.30N 88.80W 110 mph Category 2 5 10 15 Tue Sep 15 mph 3PM CDT 130 24 29.50N 89.00W 110 mph Category 2 5 10 15 Tue Sep 15 mph 9PM CDT 125 30 29.90N 89.00W 105 mph Category 2 5 9 14 Tue Sep 15 mph 3AM CDT 120 36 Wed Sep 30.40N 88.70W 100 mph Category 2 5 8 13 mph 16 9AM CDT 90 42 Wed Sep 30.90N 88.30W 75 mph Category 1 3 5 8 mph 16 3PM CDT 65 Tropical 48 Wed Sep 31.40N 87.90W 50 mph 1 2 3 mph Storm 16 3AM CDT 45 Tropical 60 32.10N 87.00W 35 mph 0 1 1 Thu Sep 17 mph Depression 3PM CDT 40 Tropical 72 32.50N 85.70W 30 mph 0 0 0 Thu Sep 17 mph Depression 3AM CDT 35 Remnant 84 33.20N 84.00W 30 mph 0 0 0 Fri Sep 18 mph Low

The yellow cone represents track error from the previous five years. Over the past five tropical cyclone seasons, the center of the storm tracked within the yellow cone 75% of the time. The cone does not represent the forecast uncertainty in the current advisory for this storm. In addition, strong winds, very high tides, large waves, and heavy rainfall can often extend well outside the yellow cone.