Favorable MJO pattern to set off east Pacific hurricane season

National Hurricane Center 5-day Graphical Tropical Weather Outlook map for the east Pacific indicating two areas of interest over the coming days.

National Hurricane Center 5-day Graphical Tropical Weather Outlook map for the east Pacific indicating two areas of interest over the coming days.

The east Pacific hurricane season officially began on May 15. So far, we have not had a named storm in that region but it’s still early. I am seeing signs that point to a change in the pattern which should allow for some activity to begin flaring up in the coming days.

As for the Atlantic, the season begins on June 1 but we’ve already had one tropical storm: Ana. Right now, there are no indications of anything trying to organize on the Atlantic side so I will focus on the east Pacific.

As of this morning, the NHC was outlining two areas of disturbed weather, both well to the southwest of Mexico, that have potential for additional development. The eastern most disturbance seems to have the best chance right now as it moves generally westward over the open waters of the Pacific.

The Pacific is now in an El Niño state which means that water temps along the Equator and then several degrees of latitude north (not so much south) are quite a bit warmer than normal.

GFS MJO status and forecast

GFS MJO status and forecast

Add to the El Niño the fact that a more favorable MJO or upward motion pattern is setting up and we have the makings of a busy time coming up for the eastern Pacific. The MJO can be thought of as a period of enhanced upward motion in the atmosphere, mainly in the tropics. Since tropical storms and hurricanes need vertical motion to thrive, a favorable upward motion pattern helps this process and leads to more convection (thunderstorms) over the tropics. Both the GFS and the ECMWF global models agree that a favorable MJO pattern is setting up shop across the region. This should act to enhance the probability for tropical storm formation in the region.

Fortunately, what ever does manage to get going is likely to remain far away from land areas due to a steering pattern that will keep any storms or hurricanes moving generally westward.

We are likely going to see quite a busy east Pacific hurricane season, similar perhaps to last year. It won’t be long before we see development closer to Mexico but for now, the action is taking root much farther to the southwest and is of no concern. It does mean, however, that the hurricane season is about to commence beyond just a point on the calendar. Pacific Mexico residents and tourists alike will need to be ready this season as El Niño years can feature powerful hurricanes due to the warmer water temperatures.

I will have more on the east Pacific activity throughout the weekend.

M. Sudduth 8:40 AM ET May 22


Ana now dumping heavy rain on portions of the Carolinas

Latest radar image from NWS Wilmington showing well defined spiral structure to TS Ana - along with very heavy rain at times under the bands

Latest radar image from NWS Wilmington showing well defined spiral structure to TS Ana – along with very heavy rain at times under the bands

The first tropical storm of the soon-to-be-official 2015 Atlantic hurricane season made landfall in South Carolina early this morning. Top winds were only about 45 mph though most places likely only saw 25 to 30 mph winds with spotty higher gusts.

The main issue with this storm has been rain and a lot of it. Some locations in southeast North Carolina have picked up over 3 inches of rain and more is expected as the day wears on.

Ana is still moving slowly, only about 5 miles per hour but should begin to increase its forward speed tonight and tomorrow. However, this is still not going to alleviate the threat of continued torrential rain as strong bands move around the circulation.

Fortunately, the wind has diminished so there should be little if any issues related to strong wind. This is good since the soil is loose now due to the excessive rainfall as of late.

Once Ana moves out of the region, it will begin to lose its tropical characteristics and transition back in to a more typical mid-latitude storm system. The remnant circulation will move out over the Atlantic by early this coming week and that will be end of the “A” storm for this season.

I’ll have more here tomorrow.

M. Sudduth 1:40 PM ET May 10


Ana now purely tropical but will not amount to much for Carolinas

Recent radar shot showing limited bands of showers moving onshore of the Carolina coastline

Recent radar shot showing limited bands of showers moving onshore of the Carolina coastline

The National Hurricane Center designated Ana as becoming purely tropical overnight. This means that the wind field has contracted more and overall resembles a tropical storm rather than the hybrid mix subtropical storm previously.

None of this will affect the outcome really. Bands of showers and occasional heavy rain will rotate onshore from the Atlantic across parts of the Carolina coastline. These bands will have periods of brief gusty winds, especially right along the immediate coast. Other than that, Ana is not expected to cause any significant issues for the region.

The official forecast track takes the storm inland over North Carolina early tomorrow morning. As the weakening system moves over cooler water beginning today, the coverage of heavy rain will decrease. However, for anyone traveling along I-95 and I-40 through the eastern Carolinas, be mindful of possible reduced visibilities within these scattered rain bands. Slow down, take it easy and don’t let the season’s first storm ruin your Mother’s Day weekend.

If you have plans to visit the beach, keep in mind that the surf is a little roughed up and the risk of rip currents is high right now. Avoid going in the water but enjoy the incredible beaches of the area.

Once Ana moves inland, it will weaken to a remnant low and move northeast and out to sea as nothing more than an interesting beginning to the Atlantic hurricane season. Does this mean we will have a busier than forecast season ahead? Not likely. In fact, storms that form from old cold fronts as Ana did, are common during El Nino years which we are in now. Ana will contribute a few ACE points to the overall score for the season. This is the measure of energy output from tropical cyclones. We typically expect to see anywhere from 95 to 105 ACE points in any given season. This year, some forecasts are calling for the total to be as low as 40. Ana will start things off with single digits and we’ll have to wait and see when and if we get another named storm or hurricane somewhere in the Atlantic to add more to the seasonal score. Right now, there is nothing to indicate any development chances coming up over the next week to 10 days.

I’ll have more here tomorrow.

M. Sudduth 8:55 AM ET May 9


Meandering Ana to bring heavy rain to the Carolinas this weekend

Subtropical storm Ana as seen in this early morning satellite picture

Subtropical storm Ana as seen in this early morning satellite picture

Ana became official late last night as the season’s first named (subtropical) storm. It is being classified as subtropical for now due to a rather large wind field, typical of a non-tropical origin storm system, especially this early in the soon-to-be-season.

The latest from the NHC tells us that Ana is moving quite slowly. Steering currents are generally weak but a slow northwest drift is likely today. This will bring the storm system on shore somewhere in South Carolina, north of Charleston, this weekend.

The effects will be minimal overall but periods of heavy rain are possible with some areas expected to receive upwards of 3 inches between now and Monday.  As a result, a flood watch is in effect for parts of the Carolinas this weekend.

Along the beach, an increase in surf, along with dangerous rip currents is likely. Water temps are still pretty cool, low 70s at best, so any swimmers/surfers who venture out will need to be mindful of the hazards. Don’t think that a weak storm like Ana can’t produce overwhelming surf conditions, play it safe.

Wind should not be too much of a problem, perhaps some gusts reaching 40 mph or so. I wouldn’t be shocked  to see scattered power outages, especially considering the ice storm we had here this past winter. Weakened or dead limbs that haven’t been trimmed back may pop loose and cause brief outages. Outside of that, the effects will be little more than something novel to discuss over the weekend.

I am going to head out to the beach, probably in South Carolina, some time tomorrow. A lot will depend on how well organized (or not) Ana becomes. It would be great to test some equipment, make sure it’s all working now as we approach the official start of the hurricane season. I also have a new camera system that was tested twice this past winter in New England for a pair of powerful Nor’easters. Here too, I think it would be a fantastic opportunity to test things in a much warmer environment. If I do venture out, I will stream live on our public Ustream channel. I’ll also post a few video clips to our app, Hurricane Impact. Figure I might as well take advantage of the situation and get a rehearsal in, so to speak, in case we have something much bigger somewhere else this coming season.

I’ll post another update on Ana early this evening.

M. Sudduth 8:55 AM ET May 8


Increasing chance for ‘something’ to develop off the Southeast coast

GFS computer model showing the potential for the coastal storm or what ever it turns out to be impacing the Carolina coast later this week

GFS computer model showing the potential for the coastal storm or what ever it turns out to be impacting the Carolina coast later this week

Quick evening update about the system trying to develop off the Florida coast…

The NHC has increased the chances of development now to 40% over the next few days. While this does not seem like much, it is interesting since the players are on the field, so to speak, to have ‘something’ develop.

When it comes to the ‘something’ part, let me explain.

Since it is only early May and water temps are marginal at best, we’re probably not looking at a true tropical storm here. It’s likely to have limited deep thunderstorms or convection and probably won’t be too well organized on satellite images. However, it has a chance, and some of the model guidance is seeing this, to develop and become a tropical storm by definition. The alternative is that is forms as a subtropical storm meaning that it is getting most of its energy from the atmosphere instead of the warm ocean. Also, a subtropical storm would have a wider, less intense wind field. The results are generally the same: squally weather over the ocean, an increase in rough surf, passing bands of rain for the coast with breezy conditions. If this were August, we would be much more concerned.

As of now, I see this as being a nuisance and something of an anomaly for the region. Any golf plans late this week along the Carolina coast may have to be put on hold. Most computer models indicate a track towards the coast or just off shore. Either way, the beaches will not be the best places to visit unless you like generally gray skies with a nice breeze off the water – with a bit of rain thrown in for good measure.

Stay tuned, it won’t be until later tomorrow or Thursday that we really see this system get going but once it does, it will provide plenty of chatter around the water cooler as we get closer to the official start of the Atlantic hurricane season. I’ll post more tomorrow morning.

M. Sudduth 7:45 PM ET May 5