HURRICANE HARVEY COE Navigation BRIEFING 10:00 AM CDT Friday, August 25, 2017 NWSNewOrleans www.weather.gov/neworleans
Situation Overview New Information Harvey continues to strengthen Max sustained winds 110 mph Category 2 Immediate Concerns Heavy rainfall with afternoon thunderstorms Long-Term Concerns Very heavy rain possible Windy with higher tides (dependent upon track and intensity of Harvey) Tornadoes Tides increasing to above normal
Threat Levels Threat Level Extreme High Moderate Low None Winds Surge Rainfall/ Flooding Tornadoes
Marine / Coastal Concerns Tropical Storm Harvey Near Term Today through Sunday SW Louisiana East wind 15 to 25 increasing to 20 to 30 knots. Seas increasing to 6 to 9 ft. Increasing swells moving northward from Harvey Numerous showers and thunderstorms-especially weekend Tides increasing to 2 to 3 feet above normal. SE Louisiana Near Shore - East wind 10 to 20 knots. Seas 3 to 5 feet. Offshore - East wind increasing 15 to 25 knots. Seas 3 to 6 feet. Increasing swells moving northward from Harvey Scattered showers and thunderstorms increasing late weekend. Tides increasing to 1 to 2 feet above normal late weekend. Longer Term Monday through next week. Highly dependent on track outcome Wind, seas, and tides could increase considerably if Harvey moves toward region Tropical Storm conditions cannot be ruled out over southwest LA coastal waters next week.
Current Satellite View
Current Satellite View Important not to concentrate only on the center of Harvey
Forecast & Rainfall: Today Frontal boundary still remains across the region and will be the focus for showers and thunderstorms today and over the next few days. This is a concern in the short term as rain could be heavy at times. Harvey still well to the south and moving towards the central/lower Texas Coast. Harvey is still strengthening this morning and will continue to strengthen before it makes landfall later today.
Forecast & Rainfall: Saturday Frontal boundary still stalled along the coast and continues to serves as a focus for rainfall. Locally heavy rain continues to be a concern. Harvey should be moving inland over central/lower Texas. Shower activity due to Harvey should start to increase over our area.
Forecast & Rainfall: Sunday Frontal boundary still on the coast and continues to serves as a focus for rainfall. Tropical moisture from Harvey could spread along the stalled frontal boundary enhancing the heavy rain risk as any thunderstorm or shower will be an efficient rain producer. Harvey still remains over south central Texas. Troipical shower with heavy rain spreading eastward. 2-3 inches locally higher in rain bands.
Forecast & Rainfall: Monday & Tuesday Frontal boundary and Harvey continues to spread tropical rainfall across the Gulf Coast. Harvey hugs the TX coastal waters and latest forecast maintains tropical storm status. 2 to 4 inches with locally double (4 to 8 inches) the amounts possible in this timeframe in some places. The risk of tornadoes begins to increase Monday night into Tuesday.
Forecast & Rainfall: Wednesday & Thursday Harvey should begin to weaken but will continue to dump rainfall over the region. An additional 2 to 4 inches with locally double (4 to 8 inches) the amounts possible in this timeframe in some places. The threat of tornadoes continues on Wednesday Still a lot of uncertainty with the track/exit progression of Harvey.
Forecast: Friday Slow moving, could be dealing with rain continuing much of next week. Note: There will likely be locally higher amounts
Expected Storm Total Rainfall Storm total rainfall forecast valid this Morning through next Friday morning Heavy rain possible Sunday night through Friday Note: Amounts MUCH higher in prolonged rainbands
Summary Harvey will be slow moving bringing lasting impacts. Forecast still remains the same as it heads towards the Texas Coast and stalls there for a few days, and then begin a slow turn to the east and northeast pushing towards Louisiana by next week. Prolonged heavy rainfall is STILL the main threat with Harvey. Even outside of Harvey we could still see locally heavy rain the next few days with the front stalled along the coast and very rich moisture builds over the region. Rainfall totals of 5 to 10 inches total for this event higher amounts southwest. Localized double amounts in prolonged rain bands. (Highly dependent on track and stalled frontal boundary)
Summary The exact track and rainfall totals is uncertain to forecast in the long-term. Tides increasing 1-2 feet above normal (SE LA) and 2 to 3 ft above normal (SW LA). Confidence is high in the next 48 hours with Harvey approaching the central/lower Texas coast. ***Even though Harvey is becoming well developed the steering currents are very weak to nonexistent and forecast models do not handle that well*** This forecast could change. Often good at the big picture, very tough to tell where heavy rain bands will set up, be ready for Flash Flood Warnings.
HURRICANE HARVEY BRIEFING Please contact WFO at 504-522-7330 or 985-649-0429 or through the LIXchat NWSChatroom You can get the latest graphics and information on this storm at www.hurricanes.gov NWSNewOrleans www.weather.gov/neworleans