| Track: https://www.star.nesdis.noaa.gov/GOES/floater.php?stormid=AL072021 It's easy to forget that storms can sometimes strengthen much more than expected. Sadly this is happening right before landfall which will occur overnight. Satellite: https://www.star.nesdis.noaa.gov/GOES/floater.php?stormid=AL072021 Recon in Grace and Henri is occurring right now: http://hurricanecity.com/recon/ Hurricane Grace Discussion Number 31 NWS National Hurricane Center Miami FL AL072021 1000 PM CDT Fri Aug 20 2021 Hurricane Grace has rapidly intensified this evening. Deep cold convection has been wrapping around the center, with some evidence of mesovorticies rotating within the eyewall following the GOES-16 GLM lightning data. The Air Force Reserve Hurricane Hunters arrived in Grace around 0000 UTC and found that the storm had intensified into Category 2 hurricane with the pressure dropping down to 967 mb, which is a pronounced deepening rate of 2 mb per hour compared to the previous advisory. More recently, the aircraft was able to pass through the northeastern eyewall, and recently found flight level winds up to 115 kt with SFMR winds of 105 kt. These observations support Grace being upgraded to a major hurricane this advisory, with maximum sustained winds of 105 kt. Some additional strengthening is possible while Grace remains over the very warm waters in the Bay of Campeche, though the hurricane should be making landfall tonight within the next 3-6 hours just south of Tuxpan, Mexico. By tomorrow morning, the storm should be well inland, and rapid weakening will likely be underway over the very mountainous terrain of mainland Mexico. The latest NHC intensity forecast now had Grace dissipating over Mexico in about 36 hours. However, as discussed in previous advisories, while the low-level circulation is expected to dissipate, the mid-level vortex is forecast to survive the passage of Mexico, and this feature is likely to lead to the development of a new tropical cyclone in the eastern Pacific basin later this weekend or early next week. Center fixes from the aircraft indicate that Grace has stayed on a mostly due westward heading, at 270/9 kt. This general motion, though with a bit more southward component should continue through landfall and dissipation. This southward deflection over often occurs with strong hurricanes in this region, due to the topographical effects of the wind field to the north ascending over the higher terrain. The official NHC track is very similar to the previous advisory, and remains near the middle of the guidance consensus. Key Messages: 1. Hurricane conditions and dangerous storm surge are likely along portions of the coast of eastern mainland Mexico beginning tonight and tomorrow morning within the Hurricane Warning area from Puerto Veracruz northward to Cabo Rojo. 2. A dangerous storm surge is likely near and to the north of the where the center of Grace crosses the coast of Mexico. 3. Through the weekend, heavy rainfall across Veracruz, Puebla, Tlaxcala, Hidalgo, northern Queretaro, and eastern San Luis Potosi will lead to significant flash and urban flooding, along with the likelihood of mudslides. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 20.7N 96.3W 105 KT 120 MPH 12H 21/1200Z 20.3N 97.9W 75 KT 85 MPH...INLAND 24H 22/0000Z 20.0N 100.9W 45 KT 50 MPH...INLAND 36H 22/1200Z...DISSIPATED $$ Forecaster Papin/Beven Hurricane Grace Advisory Number 31 NWS National Hurricane Center Miami FL AL072021 1000 PM CDT Fri Aug 20 2021 ...GRACE RAPIDLY INTENSIFIES INTO A MAJOR HURRICANE... ...LANDFALL EXPECTED IN MAINLAND MEXICO LATER TONIGHT... SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...20.7N 96.3W ABOUT 75 MI...120 KM ESE OF TUXPAN MEXICO ABOUT 105 MI...165 KM N OF VERACRUZ MEXICO MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...967 MB...28.56 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Hurricane Warning is in effect for... * The coast of mainland Mexico from Puerto Veracruz to Cabo Rojo A Tropical Storm Warning is in effect for... * The coast of mainland Mexico from north of Cabo Rojo to Barra del Tordo A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. Preparations to protect life and property should have already been completed. A Tropical Storm Warning means that tropical storm conditions are expected somewhere withing the warning area. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 1000 PM CDT (0300 UTC), the center of Hurricane Grace was located near latitude 20.7 North, longitude 96.3 West. Grace is moving toward the west near 10 mph (17 km/h) and this general motion is expected to continue through landfall. On the forecast track, the center of Grace is forecast to make landfall along the coast of mainland Mexico within the hurricane warning area later tonight. Reports from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds have increased to near 120 mph (195 km/h) with higher gusts, making Grace a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some additional strengthening is possible until Grace makes landfall, with rapid weakening expected as Grace moves inland over the mountains of central Mexico. Hurricane-force winds extend outward up to 30 miles (45 km) from the center and tropical-storm-force winds extend outward up to 150 miles (240 km). The estimated minimum central pressure from reconnaissance aircraft data is 967 mb (28.56 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Grace can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT2, WMO header WTNT42 KNHC and on the web at www.hurricanes.gov/graphics_at2.shtml?key_messages. STORM SURGE: A dangerous storm surge will raise water levels by as much as 6 to 9 ft above normal tide levels along the immediate coast within the hurricane warning area near and north of where the center makes landfall tonight. Near the coast, the surge will be accompanied by large and destructive waves. WIND: Hurricane conditions are expected within portions of the hurricane warning area in mainland Mexico tonight, with tropical storm conditions already occuring. Tropical storm conditions are expected to continue within the tropical storm warning area in mainland Mexico through tomorrow morning. RAINFALL: Grace is expected to produce the following rainfall amounts: Over Veracruz, Puebla, Tlaxcala, Hidalgo, Queretaro, and eastern San Luis Potosi...6 to 12 inches of rain with isolated maximum totals of 18 inches are expected today through Sunday. Heavy rainfall from Grace will result in significant flash and urban flooding as well as mudslides. SURF: High surf generated by Grace will affect the southern Gulf of Mexico coastline today and continue into the weekend. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 100 AM CDT. Next complete advisory at 400 AM CDT. $$ Forecaster Papin/Beven |