Monday, August 27, 2012
***Tropical Weather Mode.***
We remain in tropical weather mode until Isaac is out of our hair.
It is not necessary for me to wax eloquently as I did last night due to time constraints, and the fact that is a more certain forecast. However, it is still prudent at this juncture to post some storm thoughts & tidbits. See the video for more details.
There is good news all around tonight. Isaac has not become a hurricane yet. We have a more definitive forecast for Isaac, and lastly only very minimal effects are expected across SW Louisiana. I would almost dub Isaac as "Irritating Isaac." It is astonishing that Isaac hasn't become a hurricane yet based on some of the Recon data & especially given the low pressure reading of 979 mb. (equal to a high end category 1 or low end category 2). However, when you look at Isaac on satellite representation it isn't as big of a surprise that he hasn't climbed to the next step on the tropical ladder yet. It is still a very disorganized, ragged, & lopsided storm. This is illustrated by the strongest convection & strongest winds currently being found on the S & W side of the center of circulation. This is the complete opposite of what you normally expect. Isaac has had to fight off many mitigating factors since its inception last week. Dry air intrusion seems to be the main issue at this point, and it is clearly evident that it is being fed into the center of circulation as it has been choked off every time it tries to get going.
Certainly, we are not complaining about the fact that Isaac is a weaker storm by any means. However, Isaac will still be a force to be reckoned with for our neighbors in SE Louisiana. Isaac is forecast to make landfall late Tuesday night or early Wednesday as a category 1 storm with winds around 90 mph. This is down from the previous forecast which said 100 mph (category 2). I am starting to wonder if Isaac reaching hurricane status at all. Surely, you would think that the winds will ultimately catch up to the pressure, but if the dry air entrainment continues then it just might not. The other thing to note this evening is the reduction in forward speed. That was predicted to occur. Isaac is moving into an area that is between two surface highs, and so steering currents may collapse for a couple of days before a trough digs in & lifts out the remnants of Isaac. The storm's forward speed is around 10 mph to the NW at this time. This is compared to around 15 mph, 24 hours ago. The storm is generally moving in the aforementioned NW direction, but it has wavered between WNW and NW for the better part of the past 24 hours. This forward motion should continue until landfall before it begins to make that right hand turn and lift out as it becomes extratropical over the Mid Mississippi Valley in the latter half of the work week.
The intensity at landfall is still a big question mark. I will forecast Isaac to become a hurricane, but the current 90 mph shown by the NHC might even be a stretch at this point. However, Isaac could just as quickly ramp up to a category 2 if it becomes more right side up & symmetrical. The models were onto something when they all showed nothing stronger than a low end category 3 with most of them showing category 2 at the strongest. SE Louisiana remains the target for a direct hit with landfall likely to occur in the vicinity of the Mouth of the Mississippi River late Tuesday night or early Wednesday. I believe landfall will be in generally the same area, I see no reason to deviate from the forecast the NHC has laid out, however, I still couldn't rule out a landfall as far West as Morgan City, but between the Mouth of the Mississippi River & Grand Isle seems more logical at this point. This means SW Louisiana will only experience fringe effects on the "good side" of the storm. What does this mean for our neighbors in SE Louisiana from New Orleans and the Northshore region? Let me briefly discuss their weather before I focus on ours for just a moment or two. Isaac is a large storm, and tropical storm force winds will be felt over a large area, however, it he reaches hurricane status, the hurricane force winds will likely be confined to very small area right around the center of circulation. Based on the current track, hurricane conditions are expected for a good portion of the Southshore area of Lake Pontchartrain & the Mississippi Delta itself. The official calls for 75 mph winds with the eye or center of circulation passing near New Orleans Wednesday morning. Isaac will weaken to a tropical storm, provided he does reach hurricane status. He will weaken regardless of what intensity he is beginning shortly after landfall. The storm will then continue a slow NW heading towards Baton Rouge and they should see 60-70 mph winds with higher gusts. Winds will gradually lessen as the circulation moves into Western Mississippi. Aside from the wind, heavy, flooding rains will be the issue with as much as 8-15" of rain expected across all of SE Louisiana East of the center of circulation. Isolated areas could see 20" of rain or more. Spin off tornadoes will also be a good bet along & to the right of this center. A storm surge over 10' will be possible along the SE Louisiana coastline through Coastal Mississippi. An area totally devastated by Katrina, and is still re-building in many spots. It is ironic that Conditions will greatly improve by Thursday.
For SW Louisiana, winds will only gradually increase on Tuesday as the storm approaches the coastline. We'll have an offshore wind, so we will have no issue with storm surge it would appear. Winds will be from the N to NE at start at around 10 mph gradually increasing to 20-25 mph during the afternoon. The outermost rain bands will start to move across South Louisiana Tuesday afternoon as well, so look for rain chances to start to increase as well. Overnight winds increase to 30-35 mph with occasional gusts into tropical storm range (40-45 mph) as more squalls move across the region in the NW quadrant of the storm. It appears that our strongest winds will occur during the day Wednesday as Isaac makes his closest approach to the Lake Area. Sustained winds should be in the 35 mph range with gusts possibly up to 50 mph in the strongest squalls, but sustained tropical storm force are not expected in the Lake Area. Lafayette has a better chance of experiencing sustained tropical storm force winds due to their closer proximity to the center of circulation. Rainfall totals on our side of the state will be considerably less. Instead of the 8-15" East of the Mississippi, I'm talking about 1-4" depending on where you are across the area. The tornado threat should be non-existent for us barring any unforeseen jogs to the West of the current forecast track. Winds will subside Wednesday night into Thursday as Isaac spins down to our NE. Rain chances will continue high into Thursday before normalcy returns to South Louisiana for Friday & the all important Labor Day weekend. All watches/warnings issued on Monday morning remain in place until further notice. The Lake Charles area is under a Tropical Storm Watch & the Lafayette area is under a Tropical Storm Warning & Hurricane Watch. The Hurricane Watch extends from Morgan City, LA to the Alabama/Florida border.
Tonight, I will just post the latest advisory & a satellite picture. Models are nearly useless now since we are inside of 24 hours.
Tropical Storm Isaac
Monday, August 27, 2012
...Isaac Trying to Become a Hurricane off the SE coast of Louisiana...
Latitude: 27.1 N
Longitude: 87.0 W
This position is about 440 miles ESE of Lake Charles & 190 miles SE of the Mouth of the Mississippi River.
Winds: 70 mph w/ higher gusts. Some strengthening is expected on Tuesday before Isaac interacts with land by late Tuesday night into Wednesday. Isaac is forecast to become a category 1 hurricane sometime Tuesday.
Moving; NW @ 10 mph. This general motion is expected to continue through Tuesday, though a reduction in forward speed is expected to occur until after landfall.
Pressure: 28.91" or 979 mb.
Finally, to wrap it up...here is my forecast in text form only through Labor Day.
*Tropical Storm Watch in effect.*
Tonight...Increasing High Clouds. Low 73. NE wind 10 mph.
Tuesday...Mostly Cloudy & Breezy with a 30% chance of showers & thunderstorms in the afternoon. High 91. NE wind 20-25 mph & gusty.
Tuesday Night...Tropical Storm Conditions. Mostly Cloudy & Windy with occasional squalls. Locally heavy rainfall possible. Low 76. NE wind 25-35 mph with gusts to 45 mph after midnight. Chance of rain 60%.
Wednesday...Tropical Storm Conditions. Cloudy w/ tropical squalls off and on through the day. Rain heavy at times. High 87. North wind 30-40 mph with gusts up to 50 mph. Chance of rain 70%.
Wednesday Night...Cloudy & Windy with off and on squalls through the night. Rain heavy at times. Low 75. NW wind 25-30 mph with gusts to 40 mph, gradually decreasing through the night. Chance of rain 60%.
Thursday...Mostly Cloudy & Windy with a 60% chance of showers & thunderstorms. High 88. SW wind 15-20 mph & gusty.
Thursday Night...Mostly Cloudy with a 30% chance of showers & thunderstorms. Low 76. South wind 10 mph.
Friday...Partly Cloudy with a 20-30% chance of afternoon showers & thunderstorms. High 92. SSE wind 10-15 mph.
Friday Night...Mostly Clear. Low 75. Light SE wind. Just a bit humid for High School Football.
Saturday...Partly Cloudy with a 20% chance of showers & thunderstorms. Hot for the first weekend of college football. High 94. SE wind 10 mph.
Saturday Night...Partly Cloudy. Low 76. Light SE wind.
Sunday...Partly Cloudy with a 20% chance of showers & thunderstorms during the afternoon. High 93. SSE wind 10 mph.
Sunday Night...Mostly Clear. Low 77. Light SE wind.
Labor Day...Partly Cloudy with a 30% chance of showers & thunderstorms. No worries for your Labor Day plans! High 93. SSE wind 10 mph.
That's all for now, keep your eyes on Isaac! My next update here will be after 10p.m. Tuesday.
Have a great night & God bless!
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