August 2014 - Showers/Storms Possible To End The Month

[srainhoutx]

Enough daylight and we have our first zoomed visible imagery. The convection is displaced to the NE of the low level center due to around 30 kts of wind shear. That wind shear may relax a bit later today into tonight. The low level center is located near 95W and 27N.

[djmike]

I know its too early, but looks like the Caribbean system to form next week looks to hug the Yucatan and progress towards MX. Is this the thinking or is there a possibility of this system getting picked up and progressing northward a little. Reason Im asking is I need rain like many of you guys and Im watching these systems closely hoping for the moisture. Can do without the winds and destruction though. Thoughts?

[srainhoutx]

Update from Jeff:

Radar and satellite data along the offshore buoys and platforms indicate a surface low pressure system has formed about 150 miles south of Freeport, TX.

Deep convection has developed on the northeast side of the surface low in conjunction with low level speed convergence of an extremely moist air mass. The low is drifting toward the west at less than 10mph and should approach the middle TX coast early Thursday. Upper level winds are out of the SW over the surface system resulting in a shearing of convection off toward the north and northeast. Additionally, dry air in the mid levels is found across much of the central Gulf of Mexico which is limiting deep convection on the SW and S flanks.

Currently NHC is giving the system a 20% chance of development before it crosses the coastline on Thursday morning. A USAF recon. aircraft is scheduled to investigate the system this afternoon to determine if a tropical depression is forming.

With a defined surface circulation having now developed, this will result in some forecast changes.

Rainfall:
NE winds inland on the north side of the circulation are helping to draw drier air over W LA into E TX. PWS range from 1.5 inches north to over 2.0 inches along the coast. This will result in a strong rainfall gradient across the region today and possibly again on Thursday. Expect incoming rain bands along the coast to move inland to roughly US 59 or I-10 today and then fizzle out as they run against the drier air to the north. Rainfall amounts of 1-3 inches will be possible along the coast tapering down to less than .25 of an inch inland (north of HWY 105).

As the surface circulation moves to the middle TX coast on Thursday morning expect deep convection to develop on the N/NE sides of the low and this could be anchored across our S and SW counties from Galveston to Matagorda Bays. Could see some decent rainfall coverage and rates with this activity on Thursday morning, but once again it does not look to push very far inland of the coast…maybe I-10.

The surface low starts to become stretched out into a shear axis along the coast Friday-Saturday and this may be when the best chance of rain materializes for the entire area as deeper moisture is allowed to push further inland.

Winds:
Well defined wind pattern of low pressure over the NW Gulf has developed. NE has increased along the coast with Galveston (NE 16g23 mph) with the buoy 20 E of Galveston (NE 19g 23kts). Wave height at this buoy is 4.0 ft with a wave period of 6 seconds. Apache Platform south of High Island is ENE at 22 g 28kts. Wind profile plots at Galveston North Jetty and Pier 21 indicate a wind speed increase from roughly 12-14kts at 400am this morning to 18-22kts at 700am this morning. Wind direction is also backing from the E to the ENE and NE along the coast currently as would be expected with a develop surface low just to the south. Unless the surface low deepens more than expected should see coastal winds peak in the 20-30mph range today and early Thursday.

Tides:
ENE to NE winds will start to push water toward the coast. Pleasure Pier ran just over 1.0 ft total water level at the high tide this morning and Sabine Pass was a touch higher than that. ENE to NE winds will continue to push water today the coast today into Thursday and Friday with low pressure S and SSW of the upper TX coast producing an onshore flow. Current water levels are running higher than predictions, so not sure how accurate those predictions are looking out of the ET surge guidance using the GFS pressure fields. Appears there was a nice bump in the surge last evening of about .50 of a foot which has pushed the total water levels up and over a foot this morning. Still not expecting any overwash with these levels…really need to get up around 3.5 feet or 4.0 feet for problems to begin. With the 20E GLS buoy showing a 4.0 ft swell with a 6 second period that is not too much wave action heading for the coast…but offshore winds are increasing and swells may get up around 4-6 ft by this evening.

Will update again if needed today per USAF mission (if it happens) or any changes in the organization of the tropical system over the NW Gulf.

[Texaspirate11]

Most models have it going into South Texas?

[srainhoutx]

Most models have it going into South Texas?

The early track guidance is W into S Texas.

Here is a good link where you can watch satellite imagery as well as other data for 98L. (Note) it is updating because of the short time that this was designated an invest.

http://rammb.cira.colostate.edu/product ... r=AL982014

[rgweathergeek]

There must be some dry air inland still. Watching the radar this morning, there was a nice band just offshore of Galveston. As it rotated in the band fizzled out right over Galveston. All of the Weatherbug stations on the island are showing gusts over at or just over 20 MPH. Although the official weather station at Scholes Field was still showing mostly sunny and light winds less than 10 MPH at 8:52 AM.

https://www.dropbox.com/s/wi9pj0nvcv0cc ... m.gif?dl=0

*EDIT* And as of 9:52 Scholes Field is reporting +RA.

[Andrew]

There must be some dry air inland still. Watching the radar this morning, there was a nice band just offshore of Galveston. As it rotated in the band fizzled out right over Galveston. All of the Weatherbug stations on the island are showing gusts over at or just over 20 MPH. Although the official weather station at Scholes Field was still showing mostly sunny and light winds less than 10 MPH at 8:52 AM.

https://www.dropbox.com/s/wi9pj0nvcv0cc ... m.gif?dl=0

*EDIT* And as of 9:52 Scholes Field is reporting +RA.

The organization of the storms in the gulf has helped to bring some dry air from the NE at the lower levels. This is due to the cyclonic flow that is present from 98L. Furthermore, an anticyclonic flow that is positioned in the southern part of the gulf is shearing storms around 98L to the NE. These two factors for us is helping to keep things pretty dry locally. Going to have to look for outflow boundaries to initiate storms this evening if we get any.

[Andrew]

For reference look at what PW values look like currently across the state. Notice the tight gradient across the coastal counties and the 1.1 inches to the NE. Unfortunately this drier air is being advected this way.

[srainhoutx]

RECON is in the air S of New Orleans enroute to 98L.

[davidiowx]

Great. We probably won't get any rain out of this storm at this rate.

[Andrew]

Great. We probably won't get any rain out of this storm at this rate.

Eventually winds will start shifting from the south as the system continues moving west. On top of that a trough should make its way through parts of the state this weekend, further increasing rain chances.

[tireman4]

Any idea when the plane is supposed to arrive at 98L?

[srainhoutx]

Any idea when the plane is supposed to arrive at 98L?

In an hour or so. The plane is SSE of Houma over the Gulf.

[tireman4]

Understood. Thank you sir.

[tireman4]

Found this....

http://www.tropicaltidbits.com/recon/

[wxman57]

With luck, 98L will produce a bit of rain for Texas. Regardless of whether or not it is classified as a TD or even a weak TS, the main impact (hopefully) will be the potential for heavy rain in Texas.

My eyes are drawn to the disturbance moving into the Eastern Caribbean today (99L to be?). That one may pose a more significant risk to the Gulf by next Tue-Wed.

[tireman4]

You know Wxman 57, a nice cold front would be nice right now with lots of rain. I digress, thanks for keeping us updated ( you, Andrew and Steve). We need you all when folks get antsy.

[srainhoutx]

The AF C-130 is about 200 mile S of Lake Charles. It will not be much longer.

[Portastorm]

With luck, 98L will produce a bit of rain for Texas. Regardless of whether or not it is classified as a TD or even a weak TS, the main impact (hopefully) will be the potential for heavy rain in Texas.

My eyes are drawn to the disturbance moving into the Eastern Caribbean today (99L to be?). That one may pose a more significant risk to the Gulf by next Tue-Wed.

I'm with ya on 98L. Would love the rain!

The 12z GFS operational run develops 99L-to-be somewhat and rolls it into the central Mexican Gulf coast, well south of Texas in about a week. Maybe we could get lucky and the remnants would be drawn northward.

[srainhoutx]

The weak low is around 26.5N /95.1 W.