Atlantic Ocean Analysis: August 31 2012

Isaac
The remnants of Isaac are currently on a northern track, but will be swept east by a frontal boundary also moving to the east. Heavy rains may begin to train over areas as the system takes time to shift directions. Thus, heaviest rains can be expected in Central Illinois.

Kirk
Kirk is in a weakening phase at this time, not moving to the northeast in accordance with a frontal boundary guiding the tropical cyclone along. I am anticipating Kirk dissipating in the next couple of days, before shooting towards Europe.

Leslie (not pictured)
Leslie's track is not well known at the moment, however a general out to sea consensus has been formulated by the models. The frontal boundary guiding Kirk appears to be the instigator, and this out to sea solution appears very valid.

Andrew

Major Rains Expected for Illinois

This image shows a side-by-side of two WRF Ensemble members from the University of Illinois' website. Here, we can see that, over the next several days, the remains of tropical cyclone Isaac will be putting down massive totals.

As of now, the target areas appear to be in Central Illinois, where over 7 inches is possible. However, as the member at the right shows, northern Illinois is also at risk for some heavy rains. It will come down to a very sharp cutoff on totals, which will make a 5 mile difference contain potentially a drastic spread.

Flash flooding is a real concern, as tropical systems typically carry very high amounts of moisture with them, thus enhancing chances for torrential rainfall, possibly reaching beyond 2 inches an hour.

Andrew

Sign Up Here for 2012-2013 Personal Winter Forecasts

This is your opportunity to get a personalized winter forecast for your town!

After last year's massive success, I am bringing back the option to get your own personalized winter forecast!

Here's how you sign up:

-Comment below with your location you want to get a forecast for

I am collecting locations now on a first-come, first-serve basis. I will accomodate all forecasts, but the advantage of signing up first is your forecast will be one of the first issued!

I am collecting locations now, and forecasts will be made later on. Publishing of these forecasts is TBD, but likely in November.

Andrew

Hurricane Ileana Poses Threat to California

UW-Milwaukee

Latest model tracks indicate that Hurricane Ileana, a Category 1 hurricane with winds of 75 MPH and a central pressure of 987 millibars, making this system a minimal hurricane.

Ileana is forecast to weaken today out of hurricane strength, as models differ greatly on the track. There are a few that take the system into California, where it could move north and affect the Plains and Midwest later on, like Isaac will do.

It should be noted that the 0z GFS agrees with this idea.

Andrew

Invest 98 Spins in East Atlantic

Invest 98 is currently swirling in the eastern Atlantic, roughly around 41W, 14N. The system has winds of 30 knots and is currently moving west-northwestward.

Latest model tracks indicate that Invest 98 will not pose a threat to land, instead continuing a northwest track and going out to sea. Notice the high level clouds on the western side of the system. The Invest is very close to reaching tropical depression strength, and may do so today.

Andrew

ISAAC MAKES LANDFALL

In-house radar imagery suggests that Hurricane Isaac made its first landfall on Louisiana soil just after 6:00 PM CT this evening as a Category 1 hurricane.

The eye made it onto land at that time, now on its way to the major landfall on the main Louisiana soil. I will have more detail on this later, as well as verification on my forecasts and projected paths of Isaac.

Andrew

Horrendous Flooding Situation Setting Up in Central Gulf Coast

A horrendous flooding situation is setting up in the central Gulf Coast over the next couple days, as Isaac crawls ashore and stays in place for hours on hours. Here's a new forecast from the WRF. Amounts are in millimeters.

This is a 48 hour total precipitation forecast off the new 12z WRF. It shows 758.6 millimeters of rain that has fallen in southern Louisiana, dangerously close to New Orleans. If one does the calculations, 758.6 millimeters equates to 29.87 inches of rain in 48 hours. That is nothing to mess with, folks.

That's not the only solution printing heavy amounts of precipitation in short periods of time.

Here is the NAM 60 hour total precipitation forecast, also measured in millimeters. The white area shows 1000 millimeters and over. If we put 1000 millimeters to inches, we will find that 39.37 inches or more is predicted by the 12z NAM for the southern Louisiana area- something that cities without major levees would struggle to survive.

The Hydrometeorological Prediction Center (HPC) is being more conservative, with 16 inches predicted to fall over southeast Louisiana. Looking at other models, I find this to be on the low end. Here is my projection.

Andrew

Evacuations Recommended as Rainfall Forecasts Skyrocket

I, personally, am recommending evacuations across the New Orleans area as new rainfall data comes in.

These are two rainfall forecasts by short range models.
The top is the WRF-NMM, the bottom is the WRF-ARW. They are showing total precipitation at 75 hours on top and 72 hours on bottom.

The top image shows 1214 millimeters, or 47.8 inches of rain hitting the MS/AL border.

The bottom image shows 825 millimeters, or 32.48 inches of rain hitting New Orleans.

I am recommending evacuations at my own discretion, NOT from the NHC. Repeat, this is NOT AN OFFICIAL GOVERNMENT EVACUATION.

Andrew

Over 400 Earthquakes Hit Brawley, California

USGS 

Over 400 earthquakes hit the town of Brawley, California in the last seven days, many of which coming from the last 48 hours.

There were several earthquakes, the strongest of which measured approximately a 5.5 on the Richter scale. There have been no reports of severe damage or severe injuries, but small damage to household items has been reported (broken shelves, etc.).

If you are in an earthquake, quickly gather a prepared bag of emergency supplies and head outside to avoid possible falling debris from your house. Gas leaks and other dangerous broken pipelines can pose a serious threat to life.

Andrew

Isaac Running Out Of Time; Storm Surge A Real Threat

Isaac is running out of time as far as strengthening potential goes. He is at tropical storm strength at the moment, and has been for quite a while. Strengthening has been much slower than what had been anticipated, and this is already bumping down strength potentials for Isaac. Let's look at what Isaac looks like now.

Isaac has a very well developed western flank, with strong convection forming a neat eyewall and clear rotation evident within the structure. However, the right side of the storm is much weaker, with little to no reinforcement around Isaac's eye, and leaving the center of circulation practically open to the world.

Recent satellite looping indicates that Isaac continues to strengthen, but why has he not significantly strengthened as was expected?

This is a big part of it- Tropical Cyclone Heat Potential anomalies. When you have warmer colors on the map, that shows warmer waters are present and better for tropical cyclone formation and strengthening. However, where Isaac is now, he is in an area that is not exactly the best when it comes to supporting strong hurricanes. This, combined with persistent wind shear and dry air, has helped hamper Isaac's strengthening.

Latest models indicate the movement of Isaac into southeast Louisiana, right into New Orleans, as a hurricane. The latest model guidance shows a Category 1 hurricane making landfall on New Orleans, but the threat is far greater than that.

Isaac is, and has been, a very large storm. It has tropical storm force winds extending quite a ways from its center. What this brings me to is the concern of some heavy-duty storm surge. Take a look below at the storm surge forecast from the NHC.

This is a probability of storm surge above 10 feet. While the percentages are low, keep in mind that it is quite significant to even see a chance show up on here. Remember that New Orleans is barely above sea level, thus intensifying impacts even further than what those several hundred feet above sea level may think. Here is a forecast from the Ocean Prediction Center for storm surge.

This model from the OPC is indicating storm surge may go above 10 feet right up against New Orleans. This only continues to ignite concerns for a potentially major flooding event. Isaac is indeed large, so rainfall could be quite large as well.

I will keep you posted before, during, and after landfall.

Andrew

Mandatory Evacuations- South Florida

MANDATORY EVACUATIONS are in place for:

-Fort Meyers Beach
-Bonita Beach
-Big and Little Hickory Islands
-Black Island
-Lover's Key
-San Carlos Island

NEW GFS Brings 2x More Rain to New Orleans Than Katrina

If the new GFS were to verify, Hurricane Isaac could bring 2 TIMES MORE rain to New Orleans than Katrina did. Looking at the graphic above, we see that there were a few instances of 7.0 to 9.9 inches of rainfall where Katrina made landfall on the left graphic. There are only a couple reports of 10.0 to 16.3 inches immediately along the Gulf Coast where Katrina made landfall.

On the right graphic is a total precipitation map until Hour 93 of the new GFS. It shows over 12 inches hitting much of southeast Louisiana, with a maximum amount of just over 20 inches shown on the extreme bottom right corner of the image.

If the levees keeled over in 2005 with Katrina due to 10 inches of rain (among other factors), imagine what 20 inches of rain in a large Category 2-3 hurricane could do.

I am not saying this will happen, this is only meant as a comparison and should be treated as such.

Andrew

**ISAAC OFFICIAL FORECAST**

This is The Weather Centre's official forecast for Isaac. The Weather Centre is not related to, or affiliated with the National Hurricane Center. In the event of an evacuation order, always heed NHC warnings over our advice.

This is the official forecast for Tropical Storm Isaac. We will start out with what is making the forecasts so hard to get together.

This is a 500mb chart for 96 hours out. I highlighted two things- a trough disturbance in the Northeast, as well as Tropical cyclone Isaac. We are watching the trough to see if it influences Isaac. If Isaac happens to be in a situation where the trough does influence the system, Isaac would likely make a more easterly landfall.
However, if the trough does not take control of Isaac and goes on its merry way, Isaac would be free to go west, like many new models and ensembles have been saying in the past 24 hours. This is definitely more concerning, as we are now seeing cities like Houston, Texas and New Orleans, LA under the gun. Let's take a look at these ensembles and models.

We'll start with the NCEP ensemble group. This is from 6z, as opposed to other ensemble groups that I will be posting soon that were made at 0z- six hours earlier. Anyhow, these ensemble members are showing a varied landfall anywhere from Houston, Texas to the end of the Florida Panhandle. There does seem to be some middle ground in the Louisiana/Texas border, but the members are just too spread out to confirm that.
I think that this is a perfect example of the trough not influencing Isaac. The ensembles seem to see that the influence will not occur, thus a more westward movement will begin. I do not want to speculate on the extreme member scenarios, such as the lone member showing a Houston landfall.

This is a chart of the 0z CMC Ensembles. You can partially see a consensus of the members, bringing Isaac to New Orleans. However, note the few members also hitting Houston. I don't know if you can see that through all of the disorganized and messy lines on this image, but there are a few more members hitting Houston than there are in the NCEP, and this is concerning. It is also worrying for New Orleans, with such a tight consensus compared to the NCEP.

Lastly (and possibly the scariest) is the FNMOC Ensembles. The FNMOC Ensembles are derived of the NOGAPS model, and these two are made by the Navy. The FNMOC Ensembles are taking a tighter consensus than either of the above groups to hitting the Texas/Louisiana border, and threatening Houston ten-fold over the NCEP. Given, the NOGAPS is not a good model, therefore the FNMOC Ensembles may not be either. However, given that the models have been shifting west, one can only believe that this is a logical solution (which it very well could be).

So, the ensembles are marking out targets between the extreme west Florida Panhandle down to Houston, with a favored track hitting Louisiana and in the New Orleans area. Let's take a look at the 0z model suite.

The 0z model suite is split down the middle, with some models projecting a Florida/Alabama landfall, and others hitting Louisiana head-on. I'll just cut to the chase here. Given that Isaac is still a tropical storm and has not significantly strengthened, I am siding with the western models, as the Coriolis effect that moves storms north when they are strong appears to be working against Isaac, who remains fairly weak. Thus, a more westward movement would be anticipated.

It should be noted that the ECMWF, which originally anticipated a Louisiana track, has shifted east to join the eastern camp in their solution.

Here is a quick sketch of my track and intensity forecast. I believe Isaac will stay weak for a bit before strengthening into a Category 1 hurricane. The waters are not as warm now as they can be during the tropical season, so Category 2 strengthening should occur immediately prior to landfall. I am going with a western solution due to a very good ensemble consensus, with some models also supporting this.

Andrew


Credits: NCEP/EMC for Ensembles, UW-Milwaukee for Late and Early Models

Isaac Ensembles Shifting West; Dangerous Situation Incoming

The global model ensembles are taking a shift west, posing a danger to cities like New Orleans, that were previously not in the path of Isaac. Let's take a look.

This is the NCEP Ensembles, comprised of the GFS Ensembles. In the previous 0z suite, we saw a good consensus on Isaac hitting the Florida Panhandle. However, notice the ensemble members now more spred out. This spread appears to be favoring the west more than the east, and the 12z model suite reflected a westward shift in thinking. I'm not saying that the one member showing a Houston, Texas landfall is correct, but a westward shift is certainly something to take note of, especially on such a large scale of models and ensembles.

This is the CMC Ensemble group. These members are depicting a situation similar to that of the NCEP Ensembles, but more biased towards a MS/AL landfall. This is going along with new model thinking, and is not such a bad idea. However, there remains a considerable amount of spread among the ensembles, which can be mediocre at times, to say the best. However, this time around, the CMC ENS. may have something going for them.

Next, we have the FNMOC Ensembles. The FNMOC Ensembles are based off of the NOGAPS Model, which is from the Navy. The FNMOC ENS. are showing a much more varied, yet arguably well-composed spread, with members stretched from the Florida Panhandle to southern Texas. What I find great about this run of the FNMOC Ensembles is that it is accounting for nearly every reasonable scenario out there. Given, Isaac will likely not hit Mexico/South Texas. However, the FNMOC members are covering ground from Houston to Tallahassee, which is encompassing recent model and ensemble trends. This will be one to watch.

Lastly, the ECMWF Ensembles. Because the institute that runs the ECMWF is so strict about releasing data to the public for free, we are only able to see a mean of the ensembles, this image courtesy of Americanwx. The mean ensembles show a system making landfall in western Florida. This is a nudge to the east of ensemble thinking above, but should very well be counted in, as it was great at indicating that Isaac would be a Gulf threat.

All in all, the latest ensemble runs have been very interesting. Strangely, I am hesitant to count out any of them, for each has its own distinct trait that I find crucial in this forecast. For example, the NCEP has an ensemble group that has shifted with the models, the GEM Ensembles keep the MS/AL landfall as a consensus, and the FNMOC Ensembles account for all reasonable possibilities. This is not a common thing to see, when each group has good things going for them like this.

The question is, will a disturbance moving off the East Coast pick up Isaac?

I have marked the trough moving offshore and Isaac making landfall. The models seem to be having trouble assuming whether the trough influences Isaac and pulls it north, or does not influence Isaac and the hurricane goes west, more towards Louisiana, like the ensembles were beginning to say.

I will make a better calculation on this in the morning, when the ensembles should be a bit more settled than now.

Andrew

Isaac Threatening Florida; Hurricane Warnings Hoisted

Watches and warnings line the northern Caribbean and eastern Gulf Coast this morning, as Isaac leaves Haiti to continue towards the Gulf of Mexico.

Hurricane warnings have been hoisted in the face of Isaac in Florida, as well as tropical storm warnings blanketing Cuba. Isaac has just moved off of Haiti and appears to be heading northwest, towards the Florida Keys and the Gulf of Mexico.
If Isaac makes landfall on Cuba, it appears to be brief, and only a slight change in storm strength would likely be observed. However, if Isaac plows into Cuba, which is unlikely, the tropical storm could have issues with keeping itself together.

The latest Advanced Dvorak Technique (ADT) placement of the center puts Isaac at about 19 N longitude and 74 W latitude. This indicates Isaac has been moving northwest in the past while, but the first NHC graphic appears to show a west-northwest tilt as of the current center.
From this viewpoint, it seems a brief landfall on Cuba is likely, but nothing major as far as going through much of the country.

The forecast from the National Hurricane Center takes Isaac on a northwest path into the Florida Keys before curving north and making landfall on the Florida Panhandle. This does appear to be a fair track, but any wobble in any direction could drastically change the outcome of the track of Isaac. I am looking for hurricane warnings to be spread out across western Florida, the Panhandle, and Mississippi's into Alabama's portions of the Gulf Coast when Isaac nears.

The spread of models appears to be wanting to take Isaac a bit further west, possibly into Alabama or the extreme western Florida Panhandle. Considering the Southern US has been launching special radiosondes at 6z and 18z to aid the models in tracking Isaac, I would expect this to be a good consensus. However, it looks like a few models remain unsure, even 24 hours out, on where Isaac will be.

Intensity forecasts are also very scattered, but seem to have an idea of Category 1 hurricane strength in the next 3-4 days, before making landfall and weakening and possibly degenerating into an extratropical low. After that, some models project Isaac will shoot out to sea.

Storm surge is a big concern. The NHC is projecting that there is anywhere from a 0-30% chance of storm surge levels reaching 5 feet in Florida. The values appear to be so low because of no clear model consensus, but this remains a threat either way. Such a large storm has the potential to produce a very large storm surge area, possibly well inland of western Florida.

Andrew

Isaac Strengthening, Moving Northwest

Tropical Storm Isaac is now strengthening and appears to be in the process of beginning a northwest movement. Let's look at the past track of Isaac.

University of Wisconsin-Milwaukee

The observed track of Isaac shows a recent southern dip, followed by some regulation to the 16N longitude line. Recently, however, a sharp northwest turn was observed, bringing Isaac to about 16.5N. A northward turn is expected as Isaac strengthens. Strengthening of tropical systems commonly leads to the Coriolis effect taking over and turning storms to the north. The Coriolis effect will act as a tugboat, and veer storms to the right (north) in the northern hemisphere, and this could very well be happening now with Isaac.

SSEC CIMSS ADT

The Advanced Dvorak Technique, which helps find the center of tropical systems, has pinpointed Isaac's location at about 16.5 N and 71.35 W in the Caribbean. Looking at the satellite image superimposed with the center of Isaac, we see that the center is dangerously exposed on the west side. When we have a center of circulation (COC) with such an exposed area, it can be very easy for the atmosphere to quickly weaken Isaac. If that should happen, I could see a southward wobble happen, and more model mayhem ensue.

SSEC CIMSS ADT

The ADT also shows the strength of the system, based on satellite estimates and their own Cyclone Intensity scale, which ranges from 1 to 8 on this chart. Looking at recent observations, we see Isaac has endured some weakening in the past 24 hours. However, recent strengthening appears to be rebounding Isaac to a more stable point. This cannot be confirmed, however, until the center of circulation is re-covered.

Now... Model Mayhem Resumes!

Today's 12z European ECMWF model took a 967 millibar hurricane to the central Gulf Coast, keeping the consistency we look for and value so much in model forecasts. While the storm remains a while away, I am pondering this scenario. Isaac has already been shifting west and south and been strengthening and weakening so that a major move north has not been favorable. However, now, with the models recognizing the Gulf Coast threat, and a northwest movement seen above, this could be Isaac's time to shine, as far as moving towards the Gulf.

The GFS is much weaker, taking a 994 millibar tropical system to the Florida Panhandle. I do find this possible, but it is hard to go up against the consistency of the ECMWF. While this solution was shown in the 0z model suite last night, in which data from the Hurricane Hunters in Isaac was used, the ECMWF budged only a small amount east. Should Isaac take any wobble west, or even south, the ECMWF's solution would only become more and more likely.

The SREF is split, but many are projecting a tropical system to hit western Florida and the Panhandle, similar to the GFS. However, notice the major spread along the members. Just because you can make a big spread into a mean forecast does not mean it could be right. The wide variety of forecasts is very concerning to me, and I would like to not count in the SREF until its members can get into a good, solid solution.

Isaac is playing his tricks on us, and all you can do now is prepare. I advise (under my personal discretion, NOT the NHC's) that the Gulf Coast carefully monitor Isaac. The Florida Panhandle area, west to far eastern Louisiana should keep a close eye on Isaac, and consider making preparations for possible impact. We remain a time away, but the models seem to be coming together.

Andrew

All advice and opinions shared on here are those of mine and are not those of the National Hurricane Center. In any case, always disregard my forecasts and advice in favor of the National Hurricane Center's. This is meant as an informative article and should not be used to make major decisions, such as evacuation.

Gulf Coast Preparations Should Begin Now For Isaac

Preword: Do not take the following information as official information. Always disregard other sources in place of government warnings and advice. The following is meant as advice, but is not intended, in any way, to replace NHC forecasts and warnings. Use the following info at your own discretion.

"It's never too early to prepare. Now is the time."

Todays new model forecasts brought in a wide array of solutions, many now hitting the Florida Panhandle rather than affecting the East Coast head-on. What you see above is the European's ECMWF model, recognized as one of the, if not the best, forecasting models out there. Today's forecast off the ECMWF model proved interesting, with a 963 millibar major hurricane slamming into southwest Louisiana/far east Texas. I am not saying it will happen, nor am I saying it will not happen. However, the potential appears to be there.

We are watching a disturbance push its way to the east off the coast of the eastern United States. As you can see, the arrows on the lines show a northeast movement, and this could very well enhance Isaac's track. However, note that the disturbance is largely over the Atlantic and far from Isaac, reducing the potential for a sudden northeast turn that would possibly landfall upon the East Coast.
I want to make it clear that, should the current model consensus hold up, the system would landfall on the Florida Panhandle, move north (and possibly east), and may re-emerge into the Atlantic, where additional landfalling on the East Coast states may occur. However, at that point, Isaac will have dramatically weakened.

 The most recent model guidance as of 18z today shows a general consensus taking Isaac into the Gulf of Mexico and hitting either in the Panhandle of Florida, or more into the central Gulf Coast. Because I don't know these models as well as I do the global ones (GFS, ECMWF), I am not confident giving an assessment on the track. However, if I were to speculate, I would say that the continued westward progression with little north progression is edging the models west, as they should.

As of roughly 20z today, the center of Isaac was observed at roughly 16N longitude and 67W latitude. What I care more about is the longitude. Because Isaac remains in the general 15-17N realm, I cannot see any East Coast forecast models working out. Even a scrape with western Florida is edging out of the question. It is now up to Isaac to either strengthen and get going, or remain weak and disorganized and possibly not make it up to the status the ECMWF is projecting.

Andrew

ECMWF Slams Isaac Into Gulf Coast as Major Hurricane- Why You Shouldn't Count It Out

The 12z ECMWF run today took Tropical Storm Isaac, bombed it out again in the Gulf of Mexico, and slammed Isaac into the Gulf Coast as a major hurricane, with a central pressure of 964 millibars.

Many have been discounting this system as an outlier, and this continues, even as this is not the first time the bombing-out solution has been shown with Isaac. A very similar solution and slightly different track was shown yesterday by the ECMWF.

Now, it's a model war, like the ones we will see in winter: ECMWF vs. GFS for Isaac's track. Let's look at a major component of the track.

In this map, we can see Isaac just about to enter the Caribbean. But notice the large disturbance creating quite a commotion along the East Coast. The models are interpreting this differently. As you can see by the arrows in the dark red off the East Coast, the direction the winds are going is northeast, hence the East Coast-threat tracks being shown by other models.
The question is if the disturbance's influence will be enough to force Isaac north and take an East Coast-threatening track, like the GFS and others say, or will the system be able to pass by the strong northeast winds and pass into the Gulf of Mexico, where a dangerous scenario could unfold, as the ECMWF describes.

I did some deep digging and came upon an observation chart for 12z at 250mb. I also found the 12z GFS' 12z initialization chart at 250mb. I compared the two, and found slightly stronger winds in the GFS' forecast. While it may not seem huge now, the implications could be massive in the long range.

Now, let's check out the 2010 and 2011 model performance statistics for the Atlantic. We will start with 2010.

On the right sidebar is the skill percentage of the models, while the bottom bar has the forecast hour. If we look on the graph and find a light blue line leading the pack in skill, we look to the right and see it is the EMXI model, also known as the ECMWF. This shows that the ECMWF led the model forecasting skill for 2010. While a slight lapse may have occurred towards hour 120, the skill remains at the highest notch.

Moving on to 2011.

In 2011, we see a worse performance by the bottom forecasting models, and a tight race for the best forecasting model for 2011. If we look closely, we see the ECMWF and NHC forecasts tied in the early forecasting hours. But they both dropped off going into hour 120. Here's the thing- the EMXI model (ECMWF) dropped off just a little less than the NHC, showing that the ECMWF emerged victorious for best model track skill.

So, now with two runs of a major Gulf Coast threat under its belt, along with two best model track skill awards, one can not help but wonder if the ECMWF is correct in the assumption that the Gulf Coast is indeed at risk. I, for one, like to keep all options on the table. Frankly, I think the ECMWF is correct, and past analogs with a similar situation as Isaac think so too...

Climatologically, more systems in Isaac's position tend to go into the Gulf of Mexico and make landfall in that area, rather than hitting the East Coast. This is a dramatic shift from a very short time ago, when more analogs were pointing to an East Coast run than the Gulf of Mexico. Time will tell, but this is just another piece to add to the puzzle.

Andrew