Tropical Development In The Caribbean?

A tropical wave in the eastern Caribbean is being monitored by the National Hurricane Center (NHC) for tropical cyclone development as convection slowly increases (see Fig. 1). This tropical wave has been listed as Invest 95L by the NHC and has a 20% chance of tropical development over the next 5 days (see Fig. 2).

Fig. 1: Latest Caribbean satellite imagery
Fig. 2: NHC’s 5-day tropical outlook

Invest 95L is expected to move northwest over the next few days, providing deep tropical moisture for the Greater Antilles. The Greater Antilles will play an important variable in the evolution of this tropical wave; the rugged terrain of these islands will limit the initial development of the wave. As Invest 95L moves north of the Greater Antilles, it is possible the system will begin to organize off the east coast of Florida by late in the week.

Numerical guidance is all over the place with the development of Invest 95L. With that said, there is decent support from guidance that this wave will develop into a tropical cyclone (see Fig. 3). The European model is more aggressive with development (the American model–not so much) and suggests development into a tropical cyclone–similarly, the EPS has around a 45% of this wave developing into a tropical depression over the next 72 hours.

Fig. 3: Invest 95L intensity guidance
Fig. 4: EPS probability oof tropical depression

While development into a tropical cyclone is not imminent, this is something we need to keep an eye on. The development and track of this wave become highly questionable by mid to late week so all interests along the Southeast Coast and Gulf of Mexico need to keep an eye on future forecasts. The next name on the 2019 Tropical Cyclone list (Atlantic) is Chantal.

Tropical Depression 3 Forms East Of Florida

Tropical Depression 3 (TD3) has formed between the east coast of Florida and the Bahamas. The National Hurricane Center (NHC) classified the tropical wave as a depression this afternoon based on satellite imagery indicating a closed low-level circulation formed as well as a noticeable uptick in convection (see Fig. 1). TD3 has maximum sustained winds of 30mph as the tropical low moves northwest at 13mph.

Fig. 1: TD3 on satellite

TD3 will turn more northerly beginning Tuesday followed by a northeasterly turn in the tropical low by late Tuesday into early Wednesday (see Fig. 2). Slight strengthening is possible of TD3 over the next 24 hours. Wind shear north of the tropical low should keep TD3 a Tropical Depression or weak Tropical Storm. The NHC and most of the numerical guidance indicates only Tropical Depression intensity (see Fig. 3).

Fig. 2: NHC’s forecast track
Fig. 3: Numerical guidance intensity forecast for TD3

TD3 will not pose a significant threat to the Southeast Coast but will increase moisture for Florida and coastal areas of Georgia, South Carolina and North Carolina. Heavy rain is possible through mid-week for coastal areas of the Southeast as TD3 moves north and interacts with a cold front. Widespread 2-4″ is possible along the coast of the Southeast (see Fig. 4).

Fig. 4: WPC’s 7-day rainfall forecast

Along with coastal moisture from Florida to North Carolina, enhanced waves & rip-currents are possible for coastal areas in the Southeast. TD3 is forecasted to dissipate Wednesday morning near the coast of North Carolina.

BIG Cool Down On The Way!

The dangerous heat will relax this upcoming week for the eastern United States. A stout pattern change will take place thanks to a deep trough digging into the east Monday into Tuesday (see Fig. 1). This trough will setup a northerly flow across the east allowing a strong cold front to move across the eastern half of the United States Monday through Tuesday. Behind the cold front, temperatures and dewpoints will be much lower–making it feel very pleasant outside for late-July. The Climate Prediction Center has high probabilities of below average temperatures (days 6 through 10) for the eastern half of the United States (see Fig. 2).

Fig. 1: Deep trough (for late-July) across the eastern half of the United States (trough is depicted by blue colors)
Fig. 2: Temperature probabilities days 6 through 10

It appears the below average temperatures will remain across the eastern half of the United States through the end of the upcoming week. By the end of the upcoming week, temperatures will begin to approach seasonal levels and should return to average by next weekend.

Temperatures will be well below average for late-July during the first half of the week. High temperatures will fall into the low to mid-80s for much of the Southeast Tuesday through Thursday with lows in the 60s–a few upper 50s possible. Temperatures climb into the mid-80s by Friday. Farther north, temperatures near the Great Lakes and the Northeast will be in the mid-70s for highs with lows in the 50s. Farther west, the Southern Plains will not cool as readily but highs will fall into the mid to upper-80s with lows in the mid to upper-60s (still below average for late-July).

Atlantic Tropical Activity To Heat Up As El Niño Fades

El Niño conditions continue this summer but not for much longer. The June Niño 3.4 index (the primary ENSO measurement) was 0.6°C above the long-term average (El Niño is present when the average sea-surface temperatures across the central & eastern tropical Pacific are 0.5°C or greater over an extended period of time). The Climate Prediction Center is forecasting ENSO-neutral conditions to resume within the next month or two as the tropical Pacific cools (see Fig. 1). Over the past month, there has been a gradual decrease in equatorial Pacific sea-surface temperature anomalies (see Fig. 2). What are ENSO-neutral conditions? ENSO-neutral conditions are when neither El Niño or La Niña conditions are present.

Fig. 1: Histogram showing probabilities for El Niño (red), neutral (gray) and La Niña (blue) conditions for the remainder of 2019 into 2020 (map by Climate Prediction Center)–**while there is a slight decrease for neutral conditions from fall into winter, neutral conditions is the most likely scenario
Fig. 2: Change in sea-surface temperature anomalies since June 12th (map by Climate Prediction Center)

The state of ENSO is very important in the evolution of tropical activity across both the Atlantic and Pacific Basins. El Niño acts to suppress tropical activity in the Atlantic Basin. The reason for the suppressing of tropical activity in the Atlantic Basin is due to enhanced vertical wind shear (see Fig. 3). What is vertical wind shear? This is the changing of wind speed and direction from around 5,000 feet to 35,000 feet above the ground. Wind shear is not good for tropical cyclogenesis because the shear can act to rip apart a developing hurricane and/or prevent a tropical wave from developing any further.

Fig. 3: Typical influence of El Niño on Pacific and Atlantic seasonal hurricane activity (map by NOAA Climate.gov–based on originals by Gerry Bell)

With El Niño expected to diminish within the next month or two, it is possible the Atlantic Basin will become active if the atmosphere responds in time to the ENSO-neutral conditions. Climatologically, ENSO-neutral and La Niña tropical seasons are more active than El Niño season (see Fig. 4).

Fig. 4: Atlantic hurricane activity during El Niño, ENSO-neutral and La Niña season (map courtesy the Weather Channel)

Keep in mind, hurricane season runs from June 1st through November 30th–leaving plenty of time for tropical activity to become enhanced. It should be noted, the peak of hurricane season is August through September in which El Niño conditions will likely continue through the climatologically busiest period. It looks like the hurricane season will become more active as we head into a more climatologically active period paired with the development of ENSO-neutral conditions. Other factors can and do influence tropical activity such as the strength of the west African monsoon and the sea-surface temperatures across the Atlantic Basin.

Gulf States Likely To Be Impacted By Tropical Cyclone

There is a high probability that a tropical depression or tropical storm will develop this week over the northern Gulf of Mexico. The National Hurricane Center has given the low pressure located over the northeastern Gulf of Mexico an 90% chance of development over the next 48 hours and an 90% chance of development within the next five days (see Fig. 1). The low is currently located over the northeastern Gulf of Mexico and moving slowly west. The low is forecast to intensify into a possible Tropical Storm by late Wednesday night or early Thursday morning.

Fig. 1: NHC’s probability of development graphic

Latest numerical guidance supports the idea of strengthening and development of a Tropical Storm. This Tropical Storm will continue slowly moving west through late week across the northern Gulf of Mexico, and should continue to intensify through Friday. The Euro and GFS have trended slightly east overnight. A majority of the Euro (see Fig. 2) and GFS (see Fig. 3) ensemble members show a projected landfall of a strong topical storm somewhere between the upper-Texas coast and Louisiana by the weekend. The spaghetti plots show a wide spread in projected path (from Florida to Texas); however, there is a clustering in Louisiana (see Fig. 4).

Fig. 2: Euro ensembles track & intensity
Fig. 3: GFS ensembles track & intensity
Fig. 4: Latest spaghetti plots

It should be noted, there is a vast deal of uncertainty with the track of this system and it is too early to forecast where this Tropical Storm will make landfall. All areas from Florida to Texas need to remain on high alert this week and begin preparing for tropical storm impacts. With that said, at this point, guidance indicates the Louisiana Coast has the best chance to see a landfalling tropical system on Saturday. Barry is the next name on the list if this low is classified by the National Hurricane Center.

Regardless of the intensity of “Barry”. Heavy rain is likely along the Gulf Coast, which will lead to isolated flooding. Coastal areas from the western Florida to the upper-Texas coast will see 4-10″ of rain (see Fig. 4) this week; inland areas of Alabama, Mississippi, Texas & Louisiana will also see heavy rain. Rain chances will begin today for Florida, Georgia & Alabama then shift west into Mississippi & Louisiana by Wednesday followed by a continued west movement of precipitation into Texas by the weekend. Isolated tornadoes and rip currents are also likely.

Fig. 5: WPC’s 7-day precipitation forecast

As “Barry” moves inland, heavy rain can be expected for interior parts of the country but we will have more updates on this as the track of the tropical low becomes more certain. Keep checking back for updates!

80% Chance Of Tropical Development; Florida To Texas May See Impacts

There is a high probability that a tropical depression or tropical storm is likely to form by mid to late week over the northern Gulf of Mexico. The National Hurricane Center has given a shortwave located over central Georgia an 80% chance of development within the next five days (see Fig. 1).

Fig. 1: NHC’s probability of development graphic

The shortwave trough is currently located over central Georgia and is forecast to move south and close off into an upper-level low over the northern Gulf of Mexico by tomorrow. This will allow broad surface low to develop and slowly intensify. The steering currents are fairly weak, which will allow the low to meander over the waters of the northern Gulf of Mexico aiding in the aforementioned intensification.

Latest numerical guidance supports this idea and there’s a consensus that the intensifying low over the northern Gulf of Mexico will become a tropical depression or tropical storm by mid to late week. This depression/storm will begin to move west in the northern Gulf of Mexico from mid to late week. The Euro and GFS have trended west with the projected track of the depression/storm and now move the system west towards the coast of Louisiana & Texas by the end of the week. A majority of the Euro (see Fig. 2) and GFS (see Fig. 3) ensemble members concur with a more westward solution, too, and have a projected landfall somewhere between the upper-Texas coast and Louisiana by the weekend.

Fig. 2: Euro ensembles track & intensity
Fig. 3: GFS ensembles track & intensity

It should be noted, there is a vast deal of uncertainty with the track of this system and it is too early to forecast where this depression/storm will make landfall. All areas from Florida to Texas need to remain on high alert this week and begin preparing for tropical storm impacts. Confidence is high that a tropical depression or tropical storm will develop! Barry is the next name on the list if this low is classified by the National Hurricane Center later this week.

Regardless of tropical development. Heavy rain is likely along the Gulf Coast, which will lead to flooding. Coastal areas from Florida to the upper-Texas coast will see 4-10″ of rain (see Fig. 4) this week; inland areas of Georgia, Alabama, Mississippi & Louisiana will also see heavy rain (eventually, parts of Texas will see heavy rain, too). Rain chances will begin today & tomorrow for Florida, Georgia & Alabama then shift west into Mississippi & Louisiana by mid-week followed by a continued west movement of precipitation into Texas by the weekend. Isolated tornadoes and rip currents are also likely.

Fig. 4: WPC’s 7-day precipitation forecast

Keep checking back for updates!

Increasing Chance For Tropical Cyclone Development In Gulf Of Mexico This Week

There’s an increasing chance for tropical development in the Gulf of Mexico by mid-to late this upcoming week. A shortwave is currently located over the Tennessee Valley (see Fig. 1). This shortwave will continue to advance southeast today into Monday (see Fig. 2). As the shortwave dives southeast, a weak surface low will develop over the northeastern Gulf of Mexico. This is when the processes of tropical development become possible. The National Hurricane Center (NHC) has given this system a 40% chance of tropical development over the next five days (see Fig. 3). The EPS is also on board with tropical cyclone development in the northeastern Gulf of Mexico with probabilities of 90% (see Fig. 4).

Fig. 1: Current location of shortwave
Fig. 2: Shortwave location on Monday (tomorrow)
Fig. 3: NHC probabilities of tropical development over the next five days
Fig. 4: EPS tropical cyclone development probabilities

The low will meander over the northeastern & northern Gulf of Mexico through mid-week before moving west & eventually north. The steering flow is pretty relaxed, which will allow the low to “hangout” over the northern Gulf of Mexico through the end of the upcoming week. The slow movement of the low should allow for the low to begin to obtain tropical characteristics and intensify. By late Wednesday, the low should be located over the northeastern Gulf of Mexico; somewhere just south of the Florida Panhandle according to the Euro (see Fig. 5). At this point, the low should begin to increase in intensity.

Fig. 5: Low’s location late Wednesday

The low, after meandering and slowly moving west, should begin to move north by late week into the weekend. Guidance is indicating a landfall by late Friday into Saturday. The Euro is suggesting the low will gain tropical characteristics and move inland along the Mississippi coast as a Tropical Storm late on Saturday (see Fig. 6).

Fig. 6: Location of the possible tropical storm by late Saturday

While numerical guidance is beginning to get on board with the development of the low and slow intensification over the northern Gulf of Mexico, there are some significant differences in output. The Euro is suggesting a stronger and farther west solution than the GFS. The GFS meanders the low across the northeastern Gulf of Mexico before making landfall late Friday as a weak surface low. The Euro is much stronger and farther west, and has landfall late Saturday.

One thing is evident in the guidance. The low (or tropical storm) will be rather lopsided. The eastern side of the system would have an interaction with the Bermuda high, which would cause rapidly rising air, pull in rich & deep moisture and increase the pressure gradient. This would allow for the majority of the impacts to be realized on the eastern side of the low. Regardless of tropical development, heavy rain is likely this upcoming week along the Gulf Coast. From Florida to Louisiana, coastal areas will see 4-10″ of rain (see Fig. 7). It should be noted, the heavy rain will move inland by the weekend across the Southeast, which is not well depicted on Fig. 7.

Fig. 7: WPC’s 7-Day rainfall forecast

Forecasting the development & track of a tropical cyclone before it has developed is extremely difficult. It is possible this disturbance will not acquire tropical characteristics and possible the Euro is over intensifying this low (the Euro is by far the strongest & farthest west but the Euro has handled the shortwave well thus far and has a history of forecasting tropical cyclogenesis well). Regardless of tropical development, extremely heavy rain is likely for parts of the Gulf States. If this system becomes tropical in nature, Barry will be the designated name. Everyone from east Texas to Florida should keep abreast to the forecast this week.

Barry To Develop In The Gulf Of Mexico?

The Atlantic Basin has been fairly quiet thus far this season thanks to strong wind shear and widespread Saharan dust. However, tropical trouble is a possibility for the northern Gulf of Mexico next week. Numerical guidance is flirting with the idea of a tropical cyclone (Barry) developing by mid to late next week in the northern Gulf of Mexico. The latest runs of the European (Euro) continue to suggest tropical development next week in the northern Gulf. The GFS, which had suggested tropical development, has now backed off of this solution.

Currently, a shortwave is digging into western Tennessee (see Fig. 1). This shortwave is expected to continue advancing southeast over the weekend and move into Georgia by Monday (see Fig. 2). It appears a weak surface-low will begin to develop by early next week in response to this shortwave. This low will sit over the northeastern Gulf through mid-week and possibly begin to deepen. By late Wednesday, the Euro suggests the low will deepen and begin to retrograde west across the northern Gulf (see Fig. 3).

Fig. 1: Shortwave digging into western Tennessee today (Euro)
Fig. 2: Shortwave over Georgia by Monday (Euro)
Fig. 3: Intensifying system over northeastern Gulf by mid-week (Euro)

The solution from the Euro is possible but it should be noted the Euro solution is an outlier right now. Why is this solution possible? Wind-shear is expected to remain light (see Fig. 4) across the northern Gulf next week paired with anomalously warm sea-surface temperatures in the Gulf (see Fig. 5). These two variables may allow for deepening of the low as it moves west.

Fig. 4: Forecast wind shear mid-week (Euro)
Fig. 5: Current sea-surface temperature anomalies

By Friday morning, the Euro is suggesting the low will continue to deepen over the north-central Gulf (see Fig. 6) and be well over the warm Gulf waters (limiting iteration with land), which will continue sustaining what would be Barry. The Euro indicates Barry will remain over the north-central Gulf waters through late Saturday before making landfall Saturday evening somewhere along the Mississippi coast (see Fig. 7).

Fig. 6: “Barry” over the waters of the north-central Gulf by late week (Euro)
Fig. 7: “Barry” making landfall across the north-central Gulf over the weekend (Euro)

It should be noted, it is entirely too early to forecast a track of this potential tropical cyclone. It is difficult to forecast a track of a tropical cyclone before it has developed. It is possible this disturbance will not acquire tropical characteristics and possible the Euro is over intensifying this low. The Euro is the outlier and the only model showing such a solution (at this time).

Everyone along the Gulf (from east Texas to the Florida Panhandle) should keep abreast to the forecast next week. IF a tropical cyclone developed, any location along the Gulf would have the possibility of seeing impacts. We are not forecasting a landfall in the north-central Gulf–just showing what the Euro is currently suggesting. We will continue to have updates on this fluid situation.