from local met with Harris Co Flood Control District
Posted by cypresstx
on 6/17/2017, 9:44 am
|via our local board:|
Saturday morning briefing from Jeff (Lindner):
Disturbance over the western Caribbean and strong tropical wave (92L) over the central Atlantic now have a high (70%) chance of development over the next 5 days.
Tropical system continues to be likely in the Gulf of Mexico next week.
Gulf of Mexico:
Surface observations and satellite images indicate that showers and thunderstorms continue to gradually increase across the western Caribbean Sea and that surface pressures are starting to fall. The falling surface pressures indicates that the expected broad area of low pressure is starting to develop as forecast models have been suggesting. Based on satellite images it appears the lowering pressures is very large and likely still an opened trough axis.
Global models continue to be consistent on slowly developing a large low pressure system across the western Caribbean Sea and the southern Gulf of Mexico, but have become as consistently split on what happens with this system over the Gulf. One group of models develops the system faster and is stronger taking it quickly northward out of the western Caribbean Sea and into the western FL panhandle as a strong tropical storm, while another group of models brings a much weaker system WNW/NW into the western Gulf of Mexico with a very large area of tropical storm force winds and heavy rainfall north and east a broad surface center. Given the satellite images this morning without any sustained deep convection over any well defined center and the overall very large nature of the system gives some support to the weaker westward solution. The eastern camp of models show a stronger system evolving out of a possible vorticity center that would be rotating around the average larger circulation. While this is possible, in situations such as this, it is usually a better course to follow the larger mean center circulation which can at times have numerous vorticity centers rotating around it.
Upper air conditions are forecasted to gradually become more favorable for development as wind shear relaxes across the NW Caribbean Sea. Water vapor images show as slight digging trough axis over the southern US currently and this trough is expected to linger into the middle of next week which may help to impart some shear across the Gulf. In fact this may be one reason why the ECWMF is keeping the system weaker and all the weather to the right of the center. This would suggest the possibility of some degree of W/WSW shear across the system.
Uncertainty remains high especially on when and where a broad center may finally form and where the system may track. Will favor the weaker and western solution at this time in agreement with coordinated NHC/WPC points.
For now will make no changes to any of the forecasted seas, winds, tides, or rainfall chances until more certainty emerges. Already expecting 3-4 foot seas by Tuesday/Wednesday which will likely start to push tides up into the 1.0-1.5 foot range. Mid to late week could be very wet or bone dry depending on how much ridging aloft is maintained over the region.
Note: USAF mission is planned for Monday over the Gulf of Mexico to investigate this system
Strong tropical wave 1600 miles east of the Windward Islands is moving westward at 15-20mph and continues to show signs of organization. Conditions appear favorable for some development of this system as it nears the southern Windward Islands next week. While it would be very rare for a tropical system to form this far east this early in the season it does appear that this wave may develop. This system is embedded within the easterly flow on the south side of a sprawling sub-tropical ridge across the central Atlantic which will continue a westward motion between 15-20mph for the next several days. The track forecast is of high confidence as noted by the tight clustering of the track guidance. The intensity guidance is in poor agreement from showing no development at all to a near hurricane. Think development into a least a weak tropical storm is the most likely solution at this time prior to arrival into the southern Windward Islands. Conditions over the eastern Caribbean Sea appear hostile with strong upper level shear in place next week which will likely result in the system weakening however some of the latest ensemble members do keep the system alive into the central Caribbean Sea nowso that is something to watch.
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