Tropical Weather Discussion...Good afternoon! I hope everyone is having a great Sunday so far, please enjoy your day. I will have a regular forecast discussion posted later today, and needless to say it is one that is quite complicated. For now, here's the latest on the big weather story at this time, Tropical Storm (now Depression) Alex.
Tropical Depression Alex Advisory
10a.m. CDT Sunday, June 27, 2010
Latitude: 18.7vN
Longitude: 90.6 W
This puts the center of circulation close to emerging into the Gulf of Mexico, and it is centered about 85 miles S of Campeche, Mexico and 80 miles E of Cuidad del Carmen, Mexico.
Maximum Sustained Winds: 35 mph. This officially makes Alex a Tropical Depression, however it is still very well organized and large on satellite imagery. The temporary weakening trend will come to an end as the center of circulation emerges over the warm Gulf waters later today. Alex should regain tropical storm status either tonight or early Monday, and continued strengthening is expected from that point on.
Movement: WNW or 295 degrees @ 12 mph. Alex continues moving across the Yucatan Peninsula early this afternoon, and a decent clip. It has showed no signs of slowing down overnight, and on this track it should emerge into the Southern Gulf of Mexico later today. The general motion of WNW is expected to continue for the next 24-48 hours, however, a reduction in forward speed is expected as the steering currents weaken.
Minimum Central Pressure: 29.53" or 1000 mb. Pressure is temporarily rising to compliment the current weakening trend of the storm due to land interaction, however, pressure will begin falling almost immediately once the center emerges over the Southern Gulf.
All coastal tropical storm watches/warnings have been discontinued, but additional watches/warnings are expected downstream in the coming days.
Average rainfall amounts of 4-8" with isolated totals over 15" in mountainous areas are expected through Monday morning across Southern Mexico, the Yucatan Peninsula, Belize, and Guatemala. These rains will lead to life-threatening flash floods and mudslides.
Discussion...The interaction with land is the only thing that has impeded Alex's further development. The storm was very organized and was growing in size as it made landfall Saturday evening in Northern Belize. The storm has weakened from a strong tropical storm with 65 mph winds to a tropical depression with 35 mph winds as of this writing. However, re-strengthening is forecast to begin later today as the center of circulation emerges into the Gulf of Mexico. As you know, the storm's fuel source is warm water, and interaction with land chokes off any contact with that source. The overall structure of Alex remains impressive despite his interaction with land. The environment over the Bay of Campeche and Southern Gulf of Mexico is ripe for the expected re-strengthening trend. Alex should easily attain tropical storm status within 24 hours, and a steady state strengthening regime is forecast from there. The low-shear environment over the Gulf will also help Alex strengthen. The official forecast from most models is for Alex to remain a tropical storm until landfall in mainland Mexico, however, there are a few that suggests Alex will reach hurricane status. Based on how well the circulation is holding together, and how organized the tropical cyclone is, it is conceivable that Alex will achieve hurricane status. This is reflected in the official forecast from the NHC. The official intensity forecast is for a stronger system than any model initializes. The entire intensity forecast hinges on just exactly how much time the tropical entity spends the Gulf waters. Right now, landfall is expected in the general vicinity of Tampico, Mexico on Thursday morning as a category 1 hurricane with around 85 mph winds. The current cone of uncertainty stretches from Central Old Mexico all the way up to around Corpus Christi, Texas at 5 days. This is very typical for a forecast this far out. 5 day forecasts are subject to large errors over 200-300 miles on average.
I always stress that you should not focus simply on the black line. The black line only marks the expected forecast track of the center of circulation. The storm is much wider than just the black line. A large portion of the Gulf coast will feel some effects of the storm. However, based on the current projections the effects on SW Louisiana will be minimal. The current track will likely increase tides along the coast, and produce large swells and waves in the coastal waters. Periods of showers and squally weather are also possible during the mid-week period as the storm heads for the coast. However, the current track is not etched in stone, and while forecast confidence is high that the storm will enter the Gulf, it is a little less certain that the current projected track is indeed the one Alex will take. I have been talking for several days now about other synoptic scale features that could ultimately steer the storm. These players are still on the field. The models disagree on how much the current ridge along the Gulf coast, but most depict ridge erosion beginning Monday. Also, the idea of a rare summer cold front and associated trough is still on the table. Both of these features will be monitored as we go through the week. If the ridge holds firm, then Alex will most likely take the projected path because the ridge is a blocking mechanism for tropical systems. Lows and highs detract one another, and storms always follow the path of least resistance. The idea of a digging trough could not only help to erode the Gulf coast ridge, but also cause SW winds to develop over the Northern Gulf of Mexico out ahead of it, and this could cause Alex to bump into the flow, and be deflected to the N or NE towards the Gulf of Mexico coast. The majority of the models this morning kept Alex on the WNW trajectory into Mexico, however, there are a few that suggest an imminent threat to our part of the world. I do believe that Alex will move inland further up the coast than currently projected, increasing the threat for hurricane conditions to the Rio Grande Valley. However, at this time I don't see this storm making landfall any further north than about Corpus Christi. I urge caution here, I am not making an official forecast yet. I will stick with the hurricane center's track for the time being because they generally do a great job. The caution is that everyone needs to keep up to date on the latest information and advisories on Alex, because the entire forecast track can still change. The whole forecast depends on the advancing trough and expected weakening ridge. Only time will tell. For now, enjoy the rest of the weekend and stay tuned! You need not check anywhere else but right here for all the latest on Alex. The graphics follow.
There you see the satellite imagery as Alex gets ready to emerge into the Gulf, the official track from the NHC, the models, and the shear forecast. That's all for now, the next complete update from the National Hurricane Center will be at 4p.m. CDT, and my next update will be shortly after that time. Look for the regular forecast discussion later on this evening as well.
Have a great Sunday & God bless!
-DM-
No comments:
Post a Comment