Tropical Troubles For Gulf?

Saturday Morning Update:
The NHC has given this tropical wave a 40% chance to develop over the next five days.

Friday Evening Update:
The tropics may begin to heat up “close to home” next week as a tropical wave eventually encounters more favorable conditions for intensification. Currently, the tropical wave is sitting south and east of Florida (near the island of Hispaniola) and has a 10% chance of development over the next five days according to the National Hurricane Center (see Fig. 1).

Fig. 1: NHC monitoring tropical wave
The tropical wave will move north and westward into the eastern Gulf of Mexico by early next week. At this point, the tropical wave may begin to organize and intensify into a tropical cyclone. Wind shear is currently preventing organization (see Fig. 2) but this should lessen by mid next week across the Gulf (see Fig. 3). Numerical guidance is struggling with the evolution and movement of the tropical wave. The European is currently stronger and shows the wave intensifying potentially into a tropical cyclone (see Fig. 4). The GFS, however, keeps this as an open wave. The strength will play a role in the movement of the wave. An open wave would likely track towards the northwestern Gulf whereas a tropical cyclone would likely move towards the north-central Gulf.

Fig. 2: Current wind shear (Friday)

Fig. 3: Future wind shear (Wednesday morning)

Fig. 4: European 850mb winds (Wednesday morning)
Regardless of intensity, tropical moisture will aid in heavy rainfall for much of the Gulf. Heavy rainfall and gusty winds will impact parts of Florida as soon as this holiday weekend followed by rain chances increasing for the northeast and north-central Gulf by early to mid next week. Several inches are possible across the northern Gulf next week (see Fig. 5).

Fig. 5: 7-day rainfall totals
This tropical wave needs to be closely monitored over the weekend. Updates on potential track and intensity will be provided as uncertainty decreases.

Hurricane Lane Likely To Directly or Indirectly Impact Hawaii Later This Week

Hurricane Lane is currently a powerful category 4 hurricane with maximum sustained winds of around 150 mph, making it a borderline category 5 storm. Earlier model projections had Lane skirting to the south of the Hawaiian islands, but over time, model guidance has begun to trend northward, increasing the likelihood that Hawaii with either be indirectly or directly impacted by Lane. Hopefully, the residents of Hawaii have undertaken procedures to protect their homes such as installing High Impact Windows.

When a hurricane strengthens, the wind flow in the mid and upper-levels of the atmosphere becomes increasingly important, since those winds have a strong influence on the steering of the storm. Over the last several days, Lane has remained positioned to the south of a mid-level high pressure system that has extended as far west as the Hawaiian islands. Given that the flow around a high pressure feature in the Northern Hemisphere is clockwise and given Lane’s previous position relative to the high, the hurricane has generally been on a westward track. The issue is that as Lane continues westward, the high is going to weaken over/near Hawaii, which will eventually put Lane on the western periphery of that feature. This means that Lane will likely begin to make a northwestward turn towards the Big Island in a day or so.

There is generally a consensus between the operational European and GFS models that Hurricane Lane is going to begin making a turn northwestward towards Hawaii by mid-week. The GFS projects that the Big Island will be directly impacted by the storm, while the European model brings the storm a bit farther westward and directly has it impacting the smaller Hawaiian islands to the west.

GFS hurricane lane forecast

European hurricane lane forecast

Hurricane Lane is currently in an environment with low vertical wind shear and sufficiently warm sea surface temperatures. This has played a significant role in Lane’s recent strengthening. Lane is expected to encounter strengthening southwesterly wind shear as it approaches the islands, but the issue is that this probably won’t occur until Lane is already impacting the islands. The low-level flow is generally from east-to-west, which would be much more influential on Lane’s motion if it were weaker. In this scenario, Lane would be steered more westward. However, as long as Lane remains adequately strong which is now the most likely scenario, it will begin moving dangerously close to the islands later this week.

The Central Pacific Hurricane Center is going with a consensus between the GFS and European models in their latest track projection and has issued hurricane watches for the eastern half of the islands. Note that the Big Island, along with several of the smaller islands to the west are now in the cone of uncertainty. The forecast will have to be fine-tuned over the next couple of days, as far as whether or not there will be an actual landfall or where that could occur. However, given the size of Lane, impacts will most likely occur to Hawaii even if Lane does not technically make landfall on any of the islands. Once Lane begins to interact with Hawaii’s mountainous terrain and becomes more heavily influenced by increasing vertical wind shear, it will begin to weaken and steer westward. Since Lane will gain a lot of latitude over the next several days, this increases the odds that a large part of the island will at least be impacted, to some extent.

Hurricane Lane Track

If you are planning to be in Hawaii this week, please continue to monitor these forecasts closely. If you have plans to travel to the island and can change those plans, I encourage you to keep an eye on the latest forecasts through today and tomorrow and change plans, if necessary. Please continue to follow Firsthand Weather on Facebook and Twitter, as we will be continuously posting updates on social media.

Hector To Impact Hawaii

Hurricane Hector appears it will move close enough to Hawaii to bring gusty winds and heavy rainfall from Tuesday night into early Thursday for parts of the islands (see Fig. 1). At this hour, Hector is a major hurricane (Category 4) with maximum sustained winds of 130 mph. As Hector continues its westward movement, it should remain a hurricane as it approaches the Big Island. This is due to the favorable environmental conditions including the anomalously warm waters in the region (see Fig. 2).

Fig. 1: National Hurricane Center Forecast For Hector

Fig. 2: Current Sea-Surface Temperature Anomalies (Tropical Tidbits)

While Hector is moving westward at this hour. A northerly component to its forward motion is expected early this upcoming week. This is because Hector is moving along the southern periphery of an upper-level high (forcing the westward motion) but the high should slowly weaken as a trough builds southward allowing the northerly component (see Fig. 3). How far north Hector will track is unknown. In the latest advisory, the National Hurricane Center believes the center of Hector will remain just south of the Big Island. With that said, it is possible Hector could make landfall in Hawaii. The average track errors are still close to 150 miles this far out.

Fig. 3: 500mb Geopotential Heights (Tropical Tidbits)

Regardless of landfall, Hector will cause tropical storm conditions for parts of the Big Island and possibly Maui, Moloka’i and O’ahu. Gusty winds of 30-45mph, heavy rain showers, and rough seas are likely. Please remain on high-alert if you’re in Hawaii or have plans to travel to Hawaii this week as just a small northerly jog could bring more severe impacts.

102-Year Sea-Surface Temperature Record Broken

Crowds have been flocking to Southern California beaches this summer, and for good reason. The water temperatures are anomalously warm (see Fig. 1). Ocean temperatures have been well above-average along the Southern California coastline for much of the summer. 80°F+ water temperatures have been reported (San Diego Bay).

Fig. 1: Current SST Anomalies (TropicalTidbits.com)

Earlier this week, the sea-surface temperature (SST) at the Scripps Pier in San Diego, California hit its highest reading in the pier’s 102-year history. According to Scripps Institution of Oceanography, UC San Diego, the SST at the pier was measured was 78.6°F, which broke the previous record of 78.4°F (1931). Scripps Institution of Oceanography, UC San Diego, has measured the SSTs at the pier since 1916 as a part of its scientific research.

Winter 2018-2019 Discussion and Modoki El Niño

July and August are important months for climatologists and meteorologists to begin analyzing certain trends and variables to start the preliminary process of obtaining an idea of what may come during the winter season. There are certain areas around the World we can look to, to aid in providing a ‘snapshot’ of what the winter season may look like for the U.S. One area that is important to look at is the equatorial Pacific. The state of this region can play one of the puzzle-pieces (an important puzzle-piece) into how the winter will shape up. There are three very important variables to analyze when looking at the equatorial Pacific: I) sea-surface temperature (SST) anomalies, II) the positioning of the anomalously warm or cool SSTs, and III) the depth of the anomalously warm or cool SSTs.

As of mid-July, the state of the equatorial Pacific is trending anomalously warm which is signaling El Nino conditions developing (see Fig. 1). This is supported and is expected to continue per the majority of the models (see Fig. 2). We are currently in a neutral condition (not El Niño or La Niña); however, due to this region continuing to warm since March, the chances of El Niño developing are increasing. The Climate Prediction Center has increased the odds of El Niño developing in the winter to 65%.

Fig. 1: Current SST anomalies (Tropical Tidbits)

Fig. 2: Models ENSO predictions (IRI and CPC)

So what is El Niño? El Niño is simply a climate pattern that occurs when SSTs (in the equatorial Pacific) are above-normal for a long period of time. This climate pattern is a cycle (ENSO) in which below-normal SSTs can occur, too, in which the development of La Niña can occur. This climate cycle play an important role in shaping weather patterns around the entire World. Of significance, are the impacts of this cycle on the winter in the U.S. During an El Niño, the storm-track tends to shift significantly southward (see Fig. 3). This causes an increase in cloud-cover and precipitation for the southern U.S. In return, due to the cloud-cover and precipitation, temperatures tend to be below-average in this region. It can also lead to above-average temperatures in northern parts of the U.S. The impacts on temperatures and precipitation, however, are dependent upon the strength of the El Niño and the positioning of the warm SSTs.

Fig. 3: El Niño winter pattern in North America (CPC)

Based on the current trends and available data, it appears a weak to moderate Modoki El Niño may develop by late fall/winter. I am sure you’re wondering what differences, if any, are there between Modoki El Niño and El Niño. And yes, there are differences. An Modoki El Niño is slightly different than the conventional El Niño (see Figures: 4 and 5). Modoki El Niño features stronger warming, and at a great depth, of the central equatorial Pacific and cooling in the eastern and western tropical Pacific. This is what is occurring based on the latest SST anomalies (see Fig. 1). Also, notice the cooler temperatures along the West Coast of South America. This is a signature, when paired with the central warming, of Modoki El Niño.

Fig. 4: El Niño SST anomalies (JAMSTEC)

Fig. 5: Modoki El Niño SST anomalies (JAMSTEC)

This type of warming and cooling pattern in the tropical Pacific alters the normal winter pattern in the U.S. and has different implications than the typical El Niño on temperatures and precipitation (see Figures: 6, 7, 8 and 9). Instead of the Southwest seeing an increase in rainfall, as expected with El Niño, Modoki El Niños can cause an increase in temperatures and lack of precipitation in this region. An increase in storminess and cool temperatures can occur for South-central and Southeastern parts of the U.S. during a Modoki El Niño.

Fig. 6: El Niño temperatures (JAMSTEC)

Fig. 7: Modoki El Niño temperatures (JAMSTEC)

Fig. 8: El Niño precipitation (JAMSTEC)

Fig. 9: Modoki El Niño precipitation (JAMSTEC)

Updates will be needed as we head into August and September, but I wanted to give some insight into what I am currently analyzing for the winter season in the U.S. Please note, this is only one puzzle-piece in a medium to long range forecast. Other teleconnections can influence fall and winter patterns that have big implications on temperatures and precipitation.

Tropical Depression Three

5:30PM Eastern Update

Tropical Depression Three (TD3) has officially developed off of the coast of North Carolina. TD3 has maximum sustained winds of 30 mph and moving to the NNW at 5 mph (see Fig. 1). TD3 is expected to strengthen into a weak Tropical Storm by Saturday followed by further intensification into a hurricane by late Sunday or early Monday.

Fig. 1: National Hurricane Center Forecast

While intensification of TD3 is likely due to the warm sea-surface temperatures and a low environmental shear, landfall across the Carolinas does not look likely at this time. TD3 is slowly moving towards the NNW but should begin to meander (or nearly become stationary) over the weekend due to weak steering currents. By early next week, it appears a trough will pick-up the tropical cyclone and shunt it off the NE, thus, landfall is not expected across the Carolinas. Due to the Carolinas being on the west side of the tropical cyclone, no direct impacts are likely. The majority of the rain and wind associated with the system should remain offshore (however, there is an outside chance the outerbanks see scattered showers/storms).

With that said, if you live along the coast from Virginia down to South Carolina, it is wise to keep a close eye on the forecast. The National Hurricane Center does include the outerbanks of North Carolina in the official cone of uncertainty. Any small changes to certain upper-level features may make landfall more possible. Rip currents are a guaranteed hazard with this system along the East Coast so be careful if you’re headed to the beach.

Firsthand Weather will have updates as needed!

Tropical Update (Carolinas Need To Remain Alert)

Things have heated up in the Atlantic this week. Firsthand Weather is closely monitoring two systems: I) Invest 96 L and 2) Hurricane Beryl.

Invest 96 L
At this hour, we are keeping a close eye on a well-defined low that is spinning off of the coast of the Carolinas (see Fig. 1). Looking at the 850 mb vorticity, which shows the structure of the storm (see Fig. 2), shows Invest 96 L is compact and circular which is a positive sign for further development into a tropical cyclone (tropical depression or tropical storm) in the near future. The atmosphere has moistened paired with upper-level divergence (see Fig. 3), which has led to a substantial increase in convection associated with Invest 96 L (see Fig. 4). The National Hurricane Center (NHC) has given this low a 70% chance of development into a tropical cyclone over the next 48 hours and an 80% chance of development over the next five days.

Fig. 1: National Hurricane Center Forecast

Fig. 2: Current Vorticity Map (University of Wisconsin)

Fig. 3: Upper-Level Divergence Map (University of Wisconsin)

Fig. 4: Current Satellite Imagery

As Invest 96 L develops into a tropical cyclone (tropical depression or tropical storm) over the next couple of days, the system will track slowly north and westward towards the outerbanks of North Carolina. At the same time, a potent cold front will move into the Carolinas along with an approaching shortwave by Saturday night. Depending on the intensity of the low, it is possible it will get absorbed by the frontal system and eventually dissipate. Another possible scenario is the low intensifies and meanders just off of the coast of the Carolinas before either moving out-to-sea or towards land.

Right now, it is too early to determine if landfall will occur or if an out-to-sea scenario will occur. This situation needs to be closely monitored. If the low sits off of the coast of the Carolinas, it is possible (being on the western side) that rain and wind impacts may be minimal to nonexistent, but it is also possible that impacts may be felt if the system gets closer to the coast. Regardless, if you have beach plans in this area, it is best to stay out of the water. Rip currents will be a guaranteed hazard with this system.

Hurricane Beryl
We are also monitoring Hurricane Beryl (see Fig. 5). Beryl quickly strengthened into a hurricane and has maximum sustained winds of 80 mph with higher gusts and is moving to the west at 14 mph. Beryl should continue to strengthen over the next 24-36 hours with maximum sustained winds increasing to 100 to 110 mph. As Beryl approaches the Lesser Antilles by late this weekend, it should feel the influence of the shear over the eastern Caribbean (see Fig. 6) and weakening back into a tropical storm looks likely.

Fig. 5: National Hurricane Center Forecast

Fig. 6: Shear Map (University of Wisconsin)
Beryl should impact the islands as a tropical storm. Regardless of weakening, an increase in rain chances and gusty winds will occur for the Lesser Antilles followed by an increase in rain chances for Puerto Rico and the U.S. Virgin Islands early next week.

Please keep checking back for updates!

Tropical Storm Beryl

Satellite imagery indicates Tropical Depression Two has strengthened into a Tropical Storm. Tropical Storm Beryl developed in the central Tropical Atlantic and has maximum sustained winds of 50 mph with higher gusts. Beryl is moving to the W at 16 mph.

Fig. 1: National Hurricane Center Forecast

Shear is currently high ahead of the storm over the eastern Caribbean (see Fig. 2), which should prevent significant strengthening. However, Beryl should slowly increase in intensity over the next 24-48 hours. Right now, it appears Beryl should reach weak-hurricane status with strengthening up to around 75 mph by Saturday morning. As Beryl approaches the Lesser Antilles by late this weekend, it should feel the influence of the shear over the eastern Caribbean and weakening looks likely. Regardless of weakening, an increase in rain chances will occur for the Lesser Antilles followed by an increase in rain chances for Puerto Rico and the U.S. Virgin Islands on Sunday into Monday.

Fig. 2: Current Shear Map (University of Wisconsin)

Fig. 3: Sunday Morning Shear Map (Tropical Tidbits)

Updates will be provided as needed!

Tropical Depression Two Forms

Tropical Depression Two (TD2) formed in the central Tropical Atlantic this morning. TD2 will track westward through this week into the weekend (see Fig. 1). At this hour, TD2 has maximum sustained winds of 35 mph and moving to the W at 16 mph. TD2 is expected to strengthen into a weak Tropical Storm by Friday morning.

Fig. 1: National Hurricane Center Forecast

Shear is currently high ahead of the storm over the eastern Caribbean (see Fig. 2). As TD2 continues its trek westward, shear values are forecast to remain high in this region (see Fig. 3), which appears to keep TD2 from strengthening any further than a weak Tropical Storm. Right now, it appears TD2 may reach 50 mph intensity. As TD2 (likely as a Tropical Storm) approaches the Lesser Antilles by this weekend, it should feel the influence of the shear and it is possible weakening will occur. Regardless of weakening, an increase in rain chances will occur for the Lesser Antilles followed by an increase in rain chances for Puerto Rico and the U.S. Virgin Islands on Sunday into Monday.

Fig. 2: Current Shear Map (University of Wisconsin)

Fig. 3: Sunday Morning Shear Map (Tropical Tidbits)

This is a fluid situation so please keep checking back for updates from Firsthand Weather!

2018 Atlantic Hurricane Season Revisions

Revisions have been made to the 2018 Atlantic Hurricane Season according to Colorado State University (CSU). CSU is expecting the season to be less active than originally thought, which would lead to a below-average hurricane season for the Atlantic. This is according to an updated outlook (July 2nd, 2018) from CSU.

The main variable in the predicted reduction of named storms is due to cooler Sea-Surface Temperatures (SSTs) across the tropical Atlantic (see Fig. 1). Below-average SSTs have persisted throughout the early hurricane season and has expanded since May. Below-average SSTs in this region tends to lead to a less-active hurricane season.

Fig. 1: Sea-Surface Temperature Anomaly Map From Tropical Tidbits

Another variable that may influence the hurricane season is the potential return of El Nino conditions later this year. The waters near the equator across the eastern Pacific and central Pacific have warmed to above-average (see Fig. 2). While not technically reaching the El Nino threshold yet, wind shear has been abnormally strong over the southern Gulf of Mexico and Caribbean Sea thus far during the hurricane season. This along with the equatorial-Pacific waters warming, typically is indicative of the development of El Nino.

Fig. 2: Sea-Surface Temperature Anomaly Map From Tropical Tidbits

The new outlook from CSU now includes 11 named storms, which includes already named Subtropical Storm Alberto, for the 2018 season (see Fig. 3). Of the 11 named storms, four hurricanes are expected with one of the hurricanes reaching major status (Category 3 or higher). The previous outlook from CSU called for 14 named storms (6 hurricanes with 2 being major hurricanes).

Fig. 3: Updated 2018 Atlantic Hurricane Season Outlook

Firsthand Weather is also forecasting an average to below-average season for the Atlantic. Regardless of the number of named storms in a hurricane season, it only takes one storm making landfall to cause significant impacts.