| Track: https://www.nhc.noaa.gov/refresh/graphics_at1+shtml/?cone#contents Satellite: https://rammb-data.cira.colostate.edu/tc_realtime/storm.asp?storm_identifier=al262020 https://www.star.nesdis.noaa.gov/GOES/floater.php?stormid=AL262020 Cayman Islands radar: http://www.weather.gov.ky/portal/page/portal/nwshome/forecasthome/radar While the NHC discussion says "little change has been made to the intensity forecast near landfall" it seems like it has been upped a little more. Having points 24 hours apart before landfall makes it harder to tell. Previously, at 11pm EDT Monday, the forecast was: 96H 10/0000Z 28.6N 91.2W 85 KT 100 MPH 120H 11/0000Z 33.6N 88.4W 35 KT 40 MPH...INLAND Now at 5am EDT Tuesday: 72H 09/0600Z 25.8N 92.0W 110 KT 125 MPH 96H 10/0600Z 29.8N 91.1W 85 KT 100 MPH...INLAND The prior forecast had the 100mph forecast point just offshore. Now the 100mph forecast point is just inland. It would have weakened some at that point. I don't want to get too caught up in those details though as it could be stronger. I would note that they mention the HWRF and it seems to make landfall with winds of around major hurricane strength: https://www.tropicaltidbits.com/analysis/models/?model=hwrf®ion=26L&pkg=mslp_wind I am looking at 0Z run on Tuesday as of posting and the landfall has winds of around 98.1 knots which is about 113 mph. Again, don't focus too much on that specifically, people just need to prepare for a major hurricane landfalling somewhere along the U.S. Gulf coast. I never like counting on shear. The HWRF for example has winds as of that run at 110.8 knots (about 128mph) just six hours prior to that landfall. I don't like counting on a drop like that happening just before landfall. What if it didn't or what if it got even stronger than the forecast and then started weakening, but was still above what was expected because of being stronger earlier on and therefore had a higher peak to come down from. I am just pointing that out because so far it is strengthening rapidly. It's better to plan for it to be stronger and then hopefully have it weaken just before landfall. But you can't count on the weakening, you have to plan for the stronger storm. We'll have to see what kind of size the storm is after the Yucatan, in terms of more surge possibly if larger and in terms of how susceptible it might be to shear later on. Smaller storms can be more susceptible. Hurricane Delta Discussion Number 7 NWS National Hurricane Center Miami FL AL262020 500 AM EDT Tue Oct 06 2020 Delta has maintained a very deep central dense overcast during the past several hours, with overshooting cloud-top temperatures to -90C, and perhaps hints of an eye trying to emerge. On the last pass through the center, the Air Force plane reported a 4-mb pressure fall in one hour to 968 mb, with believable SFMR values of 80-85 kt. Thus, the initial wind speed is set to 85 kt. The hurricane is in the midst of a very impressive rapid intensification episode, having strengthened over 50 kt during the past 24 hours. I honestly don't see much that will stop it until it reaches Yucatan, due to low vertical wind shear, high deep-layer moisture, and the very warm and deep waters of the northwestern Caribbean. This is also supported by SHIPS rapid intensification probabilities that are well above 50 percent for most categories. Thus, the intensity forecast is raised to 115 kt near Yucatan landfall, closest to the HWRF forecast model, which has been a good performer this year, especially after ingesting NOAA radar data. Some weakening is expected due to land interaction, but conditions look ripe for re-intensification over the Gulf of Mexico. Almost all the guidance is higher, now showing Delta reaching category 4 status in the 2-to-3 day time frame, and the new NHC intensity forecast reflects this likelihood. However, an increase in southwesterly shear and cooler shelf waters near the northern Gulf coast should promote weakening, and little change has been made to the intensity forecast near landfall. Delta is moving much faster this morning to the west-northwest, with the latest estimates at about 13 kt. A strengthening mid-level ridge across Florida should steer the hurricane to the west-northwest or northwest during the next couple of days. Likely because of the deterioration of Gamma, model guidance is showing less poleward motion before Yucatan, and the official track is shifted to the west for the first day or so. Over the Gulf of Mexico, Delta should slow down and turn northward ahead of a trough moving eastward across Texas in a few days. Model guidance has again shifted westward, like the last cycle, and the official forecast is trended in that direction. However, it remains slightly east of the model consensus, due to a notable westward bias in some of the guidance during this hurricane season. Users are reminded to not focus on the details of the track or intensity forecasts, as the average 4-day track error is around 150 miles and the average 4-day intensity error is close to 15 mph. Key Messages: 1. Extremely dangerous storm surge and hurricane conditions are expected within portions of the northern Yucatan Peninsula of Mexico beginning tonight, and a Hurricane Warning is in effect. 2. Heavy rainfall will affect portions of the Cayman Islands, western Cuba and the northern Yucatan Peninsula through midweek. This rainfall could lead to significant flash flooding and mudslides. The potential for heavy rain and flash flooding will increase across portions of the central Gulf Coast, Tennessee Valley, and southeastern United States as Delta moves inland later this week. 3. Delta is forecast to approach the northern Gulf Coast late this week as a hurricane. While there is large uncertainty in the track and intensity forecasts, there is a significant risk of dangerous storm surge, wind, and rainfall hazards along the coast from Louisiana to the western Florida Panhandle beginning Thursday night or Friday. Residents in these areas should ensure they have their hurricane plan in place and monitor updates to the forecast of Delta. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 17.5N 81.3W 85 KT 100 MPH 12H 06/1800Z 18.7N 83.1W 100 KT 115 MPH 24H 07/0600Z 20.4N 85.8W 115 KT 130 MPH 36H 07/1800Z 21.8N 88.5W 105 KT 120 MPH 48H 08/0600Z 23.0N 90.4W 110 KT 125 MPH 60H 08/1800Z 24.2N 91.5W 115 KT 130 MPH 72H 09/0600Z 25.8N 92.0W 110 KT 125 MPH 96H 10/0600Z 29.8N 91.1W 85 KT 100 MPH...INLAND 120H 11/0600Z 34.0N 88.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Blake Hurricane Delta Advisory Number 7 NWS National Hurricane Center Miami FL AL262020 500 AM EDT Tue Oct 06 2020 ...DELTA RAPIDLY INTENSIFIES INTO A CATEGORY 2 HURRICANE... ...EXTREMELY DANGEROUS HURRICANE CONDITIONS EXPECTED FOR THE NORTHEASTERN YUCATAN PENINSULA STARTING EARLY WEDNESDAY... SUMMARY OF 500 AM EDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...17.5N 81.3W ABOUT 420 MI...675 KM ESE OF COZUMEL MEXICO ABOUT 125 MI...200 KM S OF GRAND CAYMAN MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H PRESENT MOVEMENT...WNW OR 300 DEGREES AT 15 MPH...24 KM/H MINIMUM CENTRAL PRESSURE...968 MB...28.59 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Mexico has extended the Hurricane Warning westward along the north coast of the Yucatan Peninsula to Dzilam. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Hurricane Warning is in effect for... * Tulum to Dzilam Mexico * Cozumel A Tropical Storm Warning is in effect for... * Cayman Islands including Little Cayman and Cayman Brac * Cuba province of Pinar del Rio * Isle of Youth * Punta Herrero to Tulum * Dzilam to Progresso A Tropical Storm Watch is in effect for... * Cuba province of La Habana A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 500 AM EDT (0900 UTC), the center of Hurricane Delta was located near latitude 17.5 North, longitude 81.3 West. Delta is moving toward the west-northwest near 15 mph (24 km/h). A faster northwestward motion is expected to begin later today through Wednesday night. On the forecast track, the center of Delta is expected to pass southwest of the Cayman Islands this morning, and move over the northeastern portion of the Yucatan peninsula early Wednesday. Delta is forecast to move over the southern Gulf of Mexico Wednesday afternoon, and be over the southern or central Gulf of Mexico through Thursday. Data from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds have increased to near 100 mph (155 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours, and Delta is expected to be a major hurricane over the Yucatan Peninsula Wednesday and over the Gulf of Mexico through Thursday. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 90 miles (150 km). The latest minimum central pressure reported by an Air Force Reserve Hurricane Hunter aircraft is 968 mb (28.59 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Delta can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT1, WMO header WTNT41 KNHC, and on the web at www.hurricanes.gov/text/MIATCDAT1.shtml. STORM SURGE: An extremely dangerous storm surge will raise water levels by as much as 6 to 9 feet above normal tide levels along coast of the Yucatan peninsula within the hurricane warning area, near and to right of where the center makes landfall. Near the coast, the surge will be accompanied by large and dangerous waves. WIND: Tropical storm conditions are expected in the Cayman Islands later this morning. In the Yucatan Peninsula, hurricane conditions are expected in the warning area early Wednesday, with tropical storm conditions expected later today. Tropical storm conditions are expected in the tropical storm warning area tonight and Wednesday. In Cuba, tropical storm conditions are expected tonight in the warning area and possible in the watch area near the same time. RAINFALL: 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 through midweek. This rainfall may result in areas of significant flash flooding. Over the next few days, Delta is expected to produce 2 to 4 inches of rain, with isolated higher amounts, across portions of the Cayman Islands and western Cuba. This rainfall may result in areas of flash flooding and mudslides. Later this week, Delta is expected to bring heavy rainfall to portions of the central Gulf Coast, Tennessee Valley, and southeastern United States. SURF: Swells generated by Delta will be affected land areas around the northwestern Caribbean Sea for the next day or so. 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 800 AM EDT. Next complete advisory at 1100 AM EDT. $$ Forecaster Blake |