We did at the *very last* minute get rapid core collapse in Hurricane #Isaias as extreme wind shear finally began ventilating the eye. Central pressure rose 13mb in 2 hours between the last two aircraft measurements, and the eyewall structure on radar fully opened up. However, highly dangerous conditions are ongoing on the ground as Isaias nears imminent landfall in the vicinity of Destin, #Florida. Hope everyone stays safe tonight.

#Isaias on its current heading would make landfall between Pensacola and Destin. Notable erosion of the south side of the inner core is now occurring, but that northern half-moon eyewall remains mean and contains winds >100 mph.

It's possible that the @NOAA_HurrHunter aircraft just measured the first solid evidence of vertical shear directly attacking the eyewall of Hurricane #Isaias. The last penetration measured an anomalous temperature spike at 750mb within the SW eyewall -—not within the eye—7C higher than the previously measured eye maximum. This might be evidence of a rapidly descending flow belt caused by shear laterally forcing external air into the eyewall region, leading to a massive subsidence inversion. This is often observed in high-resolution modeling (see HAFS sounding from this morning's 06Z run). The dewpoint also sharply decreased concurrent with the temperature spike measured by aircraft, supporting the possibility that this phenomenon was observed. This could foretell significant erosion of the southern eyewall in the near future, but time will tell. For now, Isaias remains as strong as ever according to the same aircraft data.

🌀 Friday video update on Category 3 Hurricane #Isaias, expected to cause life-threatening hazards of multiple types as it nears landfall likely in western #Florida tonight. Everyone please stay safe.

#Isaias became a Cat 3 hurricane this morning as central pressure measurements from hurricane hunter aircraft dropped below 960mb and max estimated surface winds increased to around 120 mph. The storm is likely near its peak intensity before shear forces a level-off and potentially some weakening just prior to landfall tonight, but unfortunately a strong hurricane strike looks baked in, regardless of how today unfolds.

Hurricane #Isaias continues to gradually gain strength tonight, with the eye now reappearing in satellite imagery, albeit mostly cloud-filled. Max winds are now estimated at 105 mph based on hurricane Hunter aircraft data. While vertical shear is increasing, it is not yet disrupting the storm core in a significant way. Isaias remains forecasted to be an intense hurricane at landfall Friday night in the far western #Florida panhandle. The exact severity of wind-related hazards will depend on whether rapid weakening begins just prior to landfall due to the onset of extreme wind shear. Regardless, dangerous hazards are expected from storm surge, wind, and flash flooding.

Hurricane #Isaias continues to intensify, with NHC now estimating max winds of 100 mph based on aircraft reconnaissance data. The storm's inner core continues to mature and stay symmetric, with a partially filled eye beginning to appear in satellite imagery. Despite being flanked by dry air while embedded in moderate southwesterly shear, robust dry entrainment pathways relative to the storm motion do not seem to be established, allowing the inner core to strengthen for now. The latest NHC forecast continues to bring Isaias into the Gulf Coast near the #Alabama, #Florida border on Friday night. Life threatening hazards from storm surge, wind, flash flooding, and tornadoes will impact a wide area regardless of the exact landfall location. Please be prepared and stay safe!

🌀 Thursday video update: Hurricane #Isaias intensifying as it begins to turn toward the Gulf Coast

Tropical Storm #Isaias has begun steadily intensifying according to aerial reconnaissance data, with strong flow of 60-65 mph (at flight level) wrapping around the previously much weaker south side of the vortex. This indicates that a nascent inner core is becoming established. Central pressure has also fallen ~5 millibars during the past 3 hours. This trend will likely continue as the inner core matures, bringing Isaias to hurricane intensity in the not-too-distant future.

🌀 Wednesday video analysis of Tropical Storm #Isaias, expected to strike the Gulf Coast as a hurricane late Friday Please forgive my slightly ill voice.

Tropical Depression Nine (#TD9) has formed and the National Hurricane Center has initiated advisories. Satellite imagery shows better defined and compact rotation associated with persistent thunderstorm activity, and nearby surface pressure measurements are falling, indicating an organizing storm. The NHC forecast is aligned with the faster grouping of models, bringing the storm into the central Gulf Coast on Friday. Per our earlier discussions this week, this would favor a stronger storm. NHC expects TD9 to become a hurricane and potentially make landfall as one. Residents in #Louisiana, #Mississippi, #Alabama, and the #Florida panhandle should pay close attention and prepare for a potential hurricane strike.

🌀 Tuesday video discussion on a new tropical storm likely to form and impact the Gulf Coast later this week. 🌀A range of different scenarios remains possible as of this morning. Folks in the region should keep a close eye on the forecast and be prepared for potential hazards.

We are monitoring a tropical disturbance in the Bay of Campeche near the tail-end of a Gulf Coast cold front that could end up impacting Gulf states in a few days. While poorly organized right now, thunderstorm activity is increasing, and this system has a chance to develop into a tropical storm later this week. Environmental conditions won't be a slam dunk here. The cold front is associated with the upper-level jet stream, causing strong wind shear along the Gulf Coast that disfavors an organizing storm. However, the position of a series of shortwave troughs over Texas through ~Friday also facilitates strong upper-level divergence over the Gulf near a jet streak entrance region, which could help the disturbance fight off the wind shear a bit. Computer models are splitting into two broad camps: 1. Most AI-based models (see AIFS example) show the system moving northeast more quickly, prior to the Texas shortwave trough lifting out. This would place the storm in the most favorable position to intensify, and would bring it into the central or eastern Gulf Coast by the weekend. 2. Several physics-based models (see ECMWF example) are slower to lift the disturbance northward, allowing the Texas shortwave to exit and the favorable jet dynamics to subside, giving way to a more purely hostile environment for a potential tropical storm. The result is a weaker, messier storm that waits until next week to attempt a move toward the Gulf Coast, if ever. Significant uncertainty remains in this scenario, but this disturbance is one to watch this week. Even if a strong storm is avoided, heavy rains may stay in the forecast for portions of the Gulf Coast. Keep an eye on the forecast from the National Hurricane Center, which currently gives a 70% chance of a tropical cyclone forming.

Crazy to see yet another hurricane threat to #Hawaii this season. Tropical Storm #Nolo has formed and will intensify into a potentially strong hurricane to the south of the Big Island over the next 3 days within a favorable environment. Complex steering currents will likely bring Nolo close enough to the Big Island to cause at least severe flooding concerns, and possibly wind hazards if it gets too close. A Hurricane Watch has been issued for the island. The other islands aren't out of the woods either, with uncertainty in the forecast track leaving a small possibility of a closer brush with Nolo. Hope everyone has a plan ready to go after dealing with Lala and Lowell earlier this year.

Hurricane #Lowell is approaching the Hawaiian Islands today with a wind field large enough to impact #Kauai, #Niihau, and #Oahu. A Hurricane Warning now extends to Kauai, and a Tropical Storm Warning to O'ahu. The worst conditions will occur later this evening and overnight tonight. Storm surge and flash flooding hazards are also expected, especially closer to the storm track. Hope everyone has a plan to stay safe today.

Watching Hurricane #Lowell move toward its brush-by of the main Hawaiian Islands tomorrow, likely bringing dangerous conditions to #Kauai, where a Tropical Storm Warning and Hurricane Watch are in place. Hope everyone stays safe in Kauai and the outlying islands to its west. Some outer bands may also bring high wind gusts and downpours to #Oahu, where I will hope for no power outages.

Watching Hurricane #Lowell and hoping the primary islands of #Hawaii can avoid a major hit. One trend to watch: whether models' ongoing southward correction for the short-term track continues. Most guidance has shifted the westward track leg closer to the monsoonal belt (pink) and farther from the trade winds (yellow). Too much of that trend would slow Lowell down, forcing the northward turn to occur farther east increasing risk to the main Hawaiian Islands. Ensemble correlation analysis confirms this sensitivity (thanks @burgwx for the 2nd plot). There remains significant uncertainty, and the storm is several days away, but it is smart to have a plan just in case. I've already dusted mine off more this year than I would have guessed.

Tropical Depression #Edouard has unfortunately produced more rainfall than expected as it tracks inland, with storm total reports peaking as high as 16-20 inches in some spots. A Flash Flood Emergency was issued for portions of Hardin and Tyler counties in eastern Texas earlier this morning as severe flooding was observed in the region. High flooding risk continues today, with Flash Flood Warnings still in effect for Liberty, Polk, Hardin, Jasper, and Tyler counties as of this hour. Hoping folks stay safe today.