1. Heavy rainfall will impact portions of southeastern Texas, Louisiana, and southern Mississippi through the middle of the week. Significant rainfall amounts are expected, potentially resulting in areas of life-threatening flash and urban flooding, along the eastern Texas coast into southwestern Louisiana. Minor to isolated major river flooding is also possible in smaller river basins and urban areas.

2. There is the danger of life-threatening storm surge inundation along the coast of Texas from Port Aransas to Sabine Pass. Residents in these areas should follow any advice given by local officials.

3. Hurricane conditions are expected within the Hurricane Warning area and Tropical storm conditions are expected with the Tropical Storm Warning area along the Texas coast.

CHANGES WITH THIS ADVISORY: The Hurricane Watch south of Port O'Connor Texas, is discontinued, and the Tropical Storm Warning south of Port Aransas, Texas, is discontinued.

The Hurricane Watch from Port O'Connor north to Freeport, Texas has been upgraded to a Hurricane Warning. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for...
- Port Aransas Texas to Sabine Pass
- Galveston Bay, Aransas Bay, San Antonio Bay, and Matagorda Bay

A Hurricane Warning is in effect for..
- Port O'Connor to Freeport Texas

A Hurricane Watch is in effect for...
- Freeport to San Luis Pass Texas A Tropical Storm Warning is in effect for...
- North of Port Aransas to Sabine Pass A Storm Surge Watch is in effect for...
- Sabine Pass to Rutherford Beach Louisiana A Storm Surge Warning means there is a danger of life threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. A Storm Surge Watch means there is a possibility of life threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov.

A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical storm force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion.

A Hurricane Watch means that hurricane conditions are possible within the watch area. Interests elsewhere in southwestern Louisiana should monitor the progress of Nicholas. For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office.

Key messages for Nicholas can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC and on the web at hurricanes.gov/graphics_at4.shtml?key_messages

RAINFALL: Nicholas is expected to produce storm total rainfall of 6 to 12 inches, with isolated maximum amounts of 18 inches, across the upper Texas coastal areas into Wednesday. Life threatening flash flooding impacts, especially in urbanized metropolitan areas, are possible across portions of the upper Texas Gulf Coast into far southwestern Louisiana. Across interior southeast Texas into southern central Louisiana and southern Mississippi, rainfall totals of 4 to 8 inches with locally higher amounts near 10 inches are expected into Thursday. This rainfall may produce areas of considerable flash and urban flooding. The potential for minor to isolated major river flooding exists across the entire region especially in smaller river basins and urban areas.

STORM SURGE: 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... Port O'Connor, TX to High Island, TX...3 5 ft Matagorda Bay and Galveston Bay...3 5 ft High Island, TX to Rutherford Beach, LA...2 4 ft Port Aransas, TX to Port O'Connor, TX...2 4 ft Aransas Bay and San Antonio Bay...2 4 ft Rutherford Beach, LA to Intracoastal City, LA...1 3 ft Sabine Lake and Calcasieu Lake...1 3 ft Baffin Bay to Port Aransas, TX...1 3 ft Corpus Christi Bay...1 3 ft Mouth of the Rio Grande to Baffin Bay...1 2 ft The deepest water will occur along the immediate coast in areas of onshore winds, 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: Tropical storm conditions are expected within the warning area across the central and upper Texas coasts through tonight. Hurricane conditions are possible in the Hurricane Watch area for the next few hours. Hurricane conditions are expected in the warning area for the next few hours.

TORNADOES: A tornado or two will be possible through Tuesday morning along the upper Texas and southwest Louisiana coast.

SURF: Swells generated by Nicholas will continue affecting portions of the northwest Gulf coast through Tuesday. These swells are likely to cause life threatening surf and rip current conditions. Please consult products from your local weather office.

At 1000 PM CDT (0300 UTC), the center of Hurricane Nicholas was located near latitude 28.4 North, longitude 95.8 West. Nicholas is moving toward the north northeast near 10 mph (17 km/h) and this general motion is expected to continue through tonight, followed by a turn toward the northeast and a slower motion by late Tuesday and an even slower eastward motion on Wednesday. On the forecast track, the center of Nicholas is expected to make landfall along the Texas coast in a few hours, move over extreme southeastern Texas on Tuesday and early Wednesday, and over southwestern Louisiana later on Wednesday.

Maximum sustained winds are near 75 mph (120 km/h) with higher gusts. Little change in strength is likely before landfall, followed by weakening after the center moves inland. Hurricane force winds extend outward up to 25 miles (35 km) from the center and tropical storm force winds extend outward up to 115 miles (185 km). A Weatherflow station at Matagorda Bay recently reported a 1 minute sustained wind of 76 mph (122 km/h) gusting to 95 mph (153 km/h). The estimated minimum central pressure is 988 mb (29.18 inches).

Very recently, a WeatherFlow Station at Matagorda Bay, Texas, reported sustained winds of 66 kt with a gust to 83 kt. Based on this observation, Nicholas is being upgraded to a hurricane on this advisory, and a Hurricane Warning is issued. No additional strengthening is anticipated until the system makes landfall, and gradual weakening is expected during the next 2-3 days while Nicholas moves over southeastern Texas and southwestern Louisiana.

Nicholas is moving north-northeastward, or around 020/10 kt. The system is currently moving through a weakness in the mid-level subtropical ridge. Within 12 to 24 hours, after Nicholas has moved inland, the ridge is forecast to weaken and leave Nicholas in an area of light steering currents. As a result, during the next couple of days, the cyclone is expected to turn eastward and slow to a crawl near southwestern Louisiana. The official forecast is slower than the previous one, but not as slow as the new model consensus.