Tropical Depression Alex Advisory
...Alex emerges into the Gulf...strengthening expected on Monday...could become the season's first hurricane before landfall later this week...
4p.m. CDT Sunday, June 27, 2010
Latitude: 19.2 N
Longitude: 90.9 W
This is about 55 miles SSW of Campeche, Mexico.
Maximum Sustained Wind: 35 mph w/ higher gusts. Alex will begin to re-strengthen shortly as the low-level center emerges over the Gulf waters. Alex should re-gain tropical storm status on Monday, and a steady state strengthening period is expected beyond that point.
Movement: WNW or 300 degrees @ 9 mph. The forward speed has slowed just a bit in the last 12 hours. A motion more to the NW with a reduction in forward speed is expected over the next couple of days. Steering currents over the Southern Gulf are forecast to weaken and nearly collapse.
Minimum Central Pressure: 999 mb. or 29.50". This is a sign that Alex remains well intact, and will strengthen once more over the Gulf, because the pressure has actually dropped a mb. or two this afternoon while the circulation was still over the SW Yucatan Peninsula.
No watches are warnings are currently in effect, but new watches and warnings are expected downstream later this week.
Rainfall totals of 4-8" with isolated amounts of near 15" in mountainous areas are expected through Monday afternoon for the Yucatan Peninsula, Southern Mexico, and Guatemala through Monday.
Discussion...Alex continues to look very impressive on satellite imagery, and the circulation most definitely remains in tact after crossing the landmass of the Yucatan Peninsula overnight and much of today. The center has just emerged into the warm waters of the Southern Gulf of Mexico, and the environment in this area is very supportive of development. Thus, re-strengthening is expected to begin overnight into Monday. Alex will attain tropical storm status once again likely during the next 12 hours. Further strengthening is expected to continue this week as long as the circulation is over the open waters of the Gulf of Mexico. Now, that the center has emerged into the Gulf, recon data will once become available as the hurricane hunters resume flying into the storm. One such plane will be investigating Alex this evening. More data will become available then. Alex is a large tropical cyclone, and tropical squalls, showers, and thunderstorms have reached the Northern Gulf coast this afternoon. The cloud mass from Alex extends all the way from Central America to the Northern Gulf. The forward motion of Alex has slowed a bit this afternoon in response to weakening steering currents. Also, Alex has begun to move more to the NW this afternoon. This motion is expected to continue the next couple of days as Alex moves around the edge of a large dome of high pressure over the Gulf coast states. The environment over the Gulf supports the idea of Alex becoming the season's first hurricane by mid-week. The current forecast still aims Alex at the coast of Northern Mexico, although the uncertainties in the forecast have increased a bit this afternoon.
Most of the forecast models have made a shift to the right (NE) further up the coast, thus increasing the threat to the U.S. However, most of them are clustered between Brownsville, TX and Corpus Christi, TX at this time. The official forecast track was shifted a bit further to the right based on the expected short-term movement to the NW, and the model shift to the right, but it remains in the middle of the pack with landfall occurring somewhere along the Mexican coast north of Tampico Thursday. This could be a trend or just a temporary rightward bias in the models. We'll see. There are always a few outliers when it comes to models, and that is certainly the case this time around. The 3-4 outliers indicate a more Northward track, which would increase the threat for an early season hurricane in our area. It is possible that Alex is beginning to feel a nudge due to a developing weakness in the aforementioned Gulf coast ridge. This is the same weakness I have discussed since the storm's inception on Friday. If a weakness has developed and is helping to steer Alex, then a revision of the forecast track further North will be forthcoming in later advisories. At this juncture, it is prudent to not only observe the model runs, but also study the movement of the synoptic features that will ultimately affect Alex. This is what we have to work with over the next couple of days. At this point, I see no reason to deviate from the official forecast track, however, I still urge everyone to keep a watchful eye on Alex. It is certainly feasible that the threat to our area will increase. When the storm became classified on Friday, I pegged Corpus Christi for landfall, and I will stick with this idea for now. I also believe that hurricane status will be obtained. The current forecast of category 2 status at landfall seems reasonable, even though many of the forecast models keep it at a lower intensity. The environs that the storm will be in are very conducive to development, and with high pressure over the top of the storm moving in tandem with it will help it develop.
The uncertainties lie with how strong the weakness that develops will be, and will it be strong enough to pull Alex further northward increasing the threat to the Northern Gulf coast. Also, there is still the previously mentioned trough hanging in the balance. This trough is on the board, and it is en route towards the Gulf, but how far will it dive, and will it be strong enough to have any effect on Alex. If indeed, Alex feels the weakness and moves on a more Northerly course, it is likely that it will feel the influence of the trough as well towards the latter half of the week. This will likely deflect Alex to the NE. It is unclear where this would make landfall occur, but as I stated yesterday, landfall is inevitable once a storm is in the Gulf. Therefore, Louisiana is by no means off the hook with Alex, but as of right now, there is no reason to believe that Alex will be an immediate threat to our area. The impacts to SW Louisiana on the current track will be minimal. Moisture will certainly increase each day, and the chances for showers and thunderstorms mainly during the afternoon hours will increase, perhaps into the likely category by mid-week through the end of the week. Winds and seas will certainly increase in the offshore waters, and there will also be a small rise in tides along the coast with a stiff onshore flow developing. It is unclear how the oil spill zone to our East will be affected by Alex, but certainly clean up operations will have to be ceased because of the increased winds and seas. What if Alex moves further North than forecast, how will that affect the intensity and when would landfall occur? The intensity forecast could change drastically if Alex does indeed move further Northward, but in my opinion the current forecast of category 2 strength at landfall will still apply for a landfall point further North. I believe this because if Alex is impacted by the advancing trough, the environment in the Northern Gulf will be a bit more hostile than the current environment over Alex. This will likely create some wind shear from the SW, and would result in weakening of the storm. However, that being said, Alex could certainly reach major hurricane status of category 3 or higher at some point in his journey over the Gulf. Again, this is not forecast at this time, and there's no reason to believe that Alex will pose a more significant threat to SW Louisiana at this time. I believe the future of Alex will be a little clearer on Monday. Stay tuned and make sure that this is your only source for complete storm information. The graphic suite follows.
That's all for this update. The next update from the National Hurricane Center will be at 10p.m. CDT, and my next update will be shortly after that time. I will also post a regular forecast discussion later tonight as well. Please check back for the latest information on Alex, and thank you in advance for reading. Audio blogs will also return tonight. Help spread the word about this blog, this is the only weather source you'll ever need here in SW Louisiana. This is Drew's Wonderful World of Weather...your source for the most accurate & complete weather information...the weather information that SW Louisiana can count on and depend on!
Have a good evening & God Bless!
-DM-
No comments:
Post a Comment