Midday Update: Harvey now a hurricane, major hurricane likely before landfall

Harvey has been strengthening this morning, with dropping pressure and increasing winds per the latest information from the hurricane hunter aircraft and dropsondes. In fact, a special 1:00pm EDT update has confirmed that Harvey has already strengthened into a hurricane, with winds of 80mph and a pressure down to 981mb. Based on latest satellite imagery, which shows thunderstorms exploding around the eye, as well as the aforementioned new observations, Harvey may be starting to rapidly intensify. It is now expected that the storm will strengthen into a Major Hurricane prior to landfall in Texas.

The potential for the storm to strengthen into a Major Hurricane prior to landfall has been present all along, but remains highly dependent on the exact speed and track of the tropical system. As it stands today, however, the conditions surrounding Harvey are highly favorable for rapid intensification. Within a low shear environment and underneath a larger, broad anticyclone, Harvey appears likely to develop asymmetrical outflow characteristics with a strong, deep core and eyewall.

Forecast model intensity guidance will not be all that useful over the next 24 hours. The issues with these stem mostly from initialization, where model guidance struggles with recognizing the storm upon initial conditions and then moving forward. Utilizing the latest data and observations will be much more useful moving forward — we will have to very carefully monitor the storms intensification through tonight.

500mb analysis shows competing steering mechanisms from two different ridges, thus a resultant very slow movement of Harvey (Pivotal Weather).

500mb analysis shows competing steering mechanisms from two different ridges, thus a resultant very slow movement of Harvey (Pivotal Weather).

The track of the system continues to come into better focus. As discussed in our morning update, the storm system will track between two very distinct atmospheric systems, falling nearly perfectly between a “tug of war” of two upper level atmospheric regions.  This suggests that Harvey will track gradually northwestward towards the coast of Central Texas through the next 24-48 hours. The storm system is then expected to slow down dramatically near or upon landfall.

The National Weather Service has issued Storm Surge Warnings for parts of the Central Texas coast, where the storm is most likely to come ashore. Both near the center and several miles outside of the landfall point, a significant storm surge (6-10 feet, possibly greater) is expected. This will have the potential to cause significant damage in the affected areas. We will continue to work to pin down the landfall point as this will be critical in determining which areas are most affected.

Today's 12z GFS shows a very prolonged, tropical moisture fetch extending from the entire Gulf and right into Harvey. This results in several days of extremely heavy rain (NEXLAB).

Today’s 12z GFS shows a very prolonged, tropical moisture fetch extending from the entire Gulf and right into Harvey. This results in several days of extremely heavy rain (NEXLAB).

As the storm slows near landfall, a tremendous concern exists for high-impact weather with the possibility of significant damage from wind, storm surge, and flooding rainfall. The threat for flooding rainfall will fan outward from the storm system as it moves gradually inland and then drives north and northeastward. Tropical moisture will continue to be drawn into the storm system within a larger area of lift in the atmosphere. With tremendous precipitable water values present in the atmosphere, widespread flooding with the potential for life-threatening impacts is expected.

Over the next 12 hours, we encourage you to stay tuned for the latest information. We will be increasing our update cycle and offering 24/7 consultation on the event. If you have questions or concerns regarding Harvey, please do not hesitate to contact us via email or cell phone. Additionally, please keep an eye out for the latest briefings which will be arriving in your inboxes multiple times per day.