#186 Postby srainhoutx » Mon Jun 15, 2015 6:17 am
Morning briefing from Jeff:
Tropical system to impact Texas over the next 24-48 hours
Excessive rainfall will potentially produce a dangerous and life threatening flash flood event over portions of SE TX and SC TX.
Discussion:
There has been little change in the overall organization of 91L overnight as the broad surface low remains tangled with an upper level trough. Recon yesterday evening did find a large area of 35-45mph winds over the southern Gulf of Mexico and the next plane will be in the system this morning. Conditions remain marginally favorable for development, but gradually improve today and into tonight. It is possible that 91L may not be purely tropical as it moves inland and this is suggested by some of the computer guidance which actually shows the system intensifying more as it moves inland and interacts with the tail end of an upper level trough…similar to TS Hermine and TS Erin.
Track:
After a very tightly track guidance cluster…more spread has crept into the models overnight and there has been a slight shift toward the west. Generally, the models remain in decent agreement on a landfall along the middle TX coast between Palacios and Rockport which places all of the upper TX coast on the “dirty” side of the system. This track is a little more uncertain than yesterday as to when the northward turn will take place over TX as the system rounds the western edge of the sub-tropical high over the SE US. Timing remains in good agreement with the system approaching the coast late tonight into early Tuesday and then inland on Tuesday. It is important to not focus on the exact track of the center given such a large and disorganized system. Most of the impacts will be east and extend well away of the actual center.
Intensity:
Little change in this aspect with a weak tropical storm the most likely event at landfall. The system looks poorly organized into landfall and then shows some degree of organization post landfall over the coastal bend and central TX. Impacts will be roughly the same if it stays as it is or is upgraded to a tropical storm.
Impacts:
Rainfall:
Rainfall remains the largest threat with this system and a significant threat.
Average rainfall amounts of 5-7 inches with isolated totals of 10-12 inches are possible along and to the east of where the center moves inland. WPC and model guidance has a swath of very heavy rainfall from roughly Galveston Bay to Matagorda Bay and inland to NE TX over the next 2-4 days along the eastern flank of the circulation. Main concerns will be training of south to north feeder bands on the eastern side of the circulation and potential for any nighttime core rainfall which the Texas Tech model is suggesting for portions of SC and SE TX late tonight into Tuesday morning and again Tuesday night.
Moisture levels continue to support very high hourly rainfall rates of 3-5 inches which will result in rapid flooding problems.
A flash flood watch will be issued for the entire region this afternoon.
Tides:
No change to the forecast tides. Tides are running about a foot above normal this morning on the Gulf beaches and up to 1.5 ft above normal in the bays. Critical high tide will be Tuesday morning in combination with strongest onshore winds on eastern side of surface center. Storm surge guidance is slightly higher this morning…nearing 2.0 ft with a total water level at Galveston 0f up to 3.0 ft Tuesday morning. The more organized the system becomes the high the tides will go due to wave run-up and stronger winds.
Tropical storm conditions will arrive into our coastal waters late this afternoon and then spread toward the coast tonight. Offshore seas will build to near 8-12 ft with nearshore seas 6-8 feet which will also bring a decent volume of water toward the coast. Will be very close to the critical 4.0 ft tide levels on Tuesday morning and only expecting a slow fall with sustained onshore winds all day Tuesday into Wednesday.
Winds:
Tropical storm force winds will be possible along the coast starting late tonight and into Tuesday as the circulation makes landfall. Winds of 35-45mph will be likely offshore, inland bays, and along the coast with speeds of 25-35mph inland.
Tornadoes:
SE TX will fall in the favored tornado production section of the landfalling system with models showing good feeder band structures across the area. Expect the tornado threat to increase this afternoon and remain tonight into Tuesday as bands move inland off the Gulf of Mexico
Will await the newest recon data this morning. An upgrade will require some forecast changes mainly to the winds and wind fields…depending on what the plane finds. Other impacts should remain generally unchanged.
0 likes
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Ike/Harvey
Member: National Weather Association
Wx Infinity Forums
http://wxinfinity.com/index.phpFacebook.com/WeatherInfinity
Twitter @WeatherInfinity
my Cowboys 
