WTNT34 KNHC 071453 TCPAT4 BULLETIN Tropical Storm Isaias Advisory Number 4 NWS National Hurricane Center Miami FL AL092026 1000 AM CDT Wed Oct 07 2026 ...HURRICANE AND STORM SURGE WATCHES ISSUED FOR PORTIONS OF THE NORTHERN GULF COAST FOR STRENGTHENING ISAIAS... SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...22.4N 93.6W ABOUT 260 MI...420 KM WNW OF PROGRESO MEXICO ABOUT 540 MI...870 KM SSW OF THE MOUTH OF THE MISSISSIPPI RIVER MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...ENE OR 70 DEGREES AT 8 MPH...13 KM/H MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Storm Surge Watch has been issued from the Mouth of the Mississippi River eastward to Yankeetown, Florida. A Hurricane Watch has been issued for the northern Gulf Coast from Bay St. Louis, Mississippi to Indian Pass, Florida. A Tropical Storm Watch has been issued for the northern Gulf Coast from the Jefferson/Plaquemines Parish line, Louisiana to west of Bay St. Louis, and from east of Indian Pass to Aucilla River, Florida. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Watch is in effect for... * Mouth of the Mississippi River to Yankeetown A Hurricane Watch is in effect for... * Bay St. Louis to Indian Pass A Tropical Storm Watch is in effect for... * Jefferson/Plaquemines Parish line to west of Bay St. Louis * East of Indian Pass to Aucilla River 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 Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests in the Yucatan Peninsula of Mexico and elsewhere around the U.S. northern Gulf Coast should closely monitor the progress of this system. Additional watches and warnings could be required for a portion of the U.S. northern Gulf coast later today. 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. DISCUSSION AND OUTLOOK ---------------------- At 1000 AM CDT (1500 UTC), the center of Tropical Storm Isaias was located by an Air Force Reserve Hurricane Hunter aircraft near latitude 22.4 North, longitude 93.6 West. Isaias is moving toward the east-northeast near 8 mph (13 km/h). A continued east-northeastward motion is expected today, followed by a turn toward the northeast and north on Thursday and Friday. On the forecast track, Isaias is expected to pass to the north of the Yucatan Peninsula on Thursday and approach the U.S. northern Gulf Coast on Friday. Maximum sustained winds have increased to near 45 mph (75 km/h) with higher gusts. Rapid strengthening is forecast over the next day or two, and Isaias is expected to become a hurricane by Thursday. Tropical-storm-force winds extend outward up to 45 miles (75 km) from the center. The estimated minimum central pressure is 1000 mb (29.53 inches) based on Air Force dropsonde data. HAZARDS AFFECTING LAND ---------------------- Key messages for Isaias can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC. 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... Ocean Springs, MS to Indian Pass, FL...5-7 ft Mobile Bay...5-7 ft Mouth of the Mississippi River, LA to Ocean Springs, MS...3-5 ft Indian Pass, FL to Aucilla River, FL...3-5 ft Aucilla River, FL to Yankeetown, FL...2-4 ft Lake Pontchartrain...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. For a complete depiction of areas at risk of storm surge inundation, please see the National Weather Service Peak Storm Surge Graphic, available at hurricanes.gov/graphics_at4.shtml?peakSurge. WIND: Hurricane conditions could begin in the Hurricane Watch area late Friday, and tropical storm conditions could begin in the watches areas midday Friday. Gusty winds are possible in portions of the Yucatan Peninsula on Thursday. RAINFALL: Tropical Storm Isaias is expected to produce rainfall amounts of 2 to 4 inches through Thursday across coastal portions of the Bay of Campeche with isolated higher amounts possible in the states of Campeche and western Yucatan. From Friday through the weekend, the system is expected to produce rainfall amounts of 3 to 6 inches, with localized totals up to 10 inches, across the central U.S. Gulf Coast extending from far southeastern Louisiana to the Florida Panhandle. Rainfall amounts of 1 to 3 inches, with localized amounts up to 5 inches, are possible across much of the Southeast as far north as the Tennessee Valley and the Carolinas. Flash and urban flooding, along with isolated river flooding, will be possible. For a complete depiction of forecast rainfall associated with Tropical Storm Isaias, please see the National Weather Service Storm Total Rainfall Graphic available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero SURF: Swells are expected to affect the western and northern portions of the Yucatan Peninsula beginning on Thursday and spread northward toward the Gulf Coast late this week. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. A depiction of rip current risk for the United States can be found at: hurricanes.gov/graphics_at4.shtml?ripCurrents NEXT ADVISORY ------------- Next intermediate advisory at 100 PM CDT. Next complete advisory at 400 PM CDT. $$ Forecaster Blake