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Potential Tropical Cyclone Three Prompts Warnings and Watches for Louisiana and Texas

An area of low pressure designated Potential Tropical Cyclone Three moved into the Gulf of Mexico on Monday and the National Hurricane Center issued Tropical Storm Warnings and Watches for Louisiana and Texas.  At 11:00 p.m. EDT on Monday the center of Potential Tropical Cyclone Three was located at latitude 24.4°N and longitude 89.5°W which put it about 380 miles (610 km) south-southeast of Morgan City, Louisiana.  It was moving toward the north-northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1000 mb

A Tropical Storm Warning is in effect for the portion of the coast from Intracoastal City, Louisiana to the mouth of the Pearl River.  A Tropical Storm Watch has been issued for the portion of the coast from High Island, Texas to Intracoastal City, Louisiana.

The circulation of Potential Tropical Cyclone 03 is not very well organized.  The system does have a well defined low level center of circulation.  However, there are no thunderstorms near the low level center.  All of the strong showers and thunderstorms are occurring in bands well to the east of the center of circulation.  Some of those bands do contain winds to tropical storm force.  An upper level low over the northwestern Gulf of Mexico is producing strong southwesterly winds which are blowing over the top of the low level center.  The strong vertical wind shear created by those winds is preventing the development of storms closer to the low level center.

The environment around Potential Tropical Cyclone 03 will remain unfavorable for intensification on Tuesday.  The system will move move water where the Sea Surface Temperature is near 29°C.  So, there will be enough energy to support intensification.  However, the upper level low will continue to produce strong vertical wind shear over the low level center of circulation.  The upper low is forecast to move slowly toward the northwest.  It is possible that the strength of the upper level winds over the northwestern Gulf of Mexico could diminish in a day or two.  If the shear decreases, thunderstorms could form closer to the center and if the structure of the system takes on a more tropical appearance, it could be designated Tropical Storm Cindy.

Potential Tropical Cyclone 03 is moving around the western end of the subtropical high over the Atlantic Ocean.  The high is steering the system toward the north-northwest and that general motion is expected to continue.  On its anticipated track Potential Tropical Cyclone 03 is expected to approach the coast of Louisiana in about 48 hours.  The steering winds could weaken when the system gets closer to the coast and the uncertainty about the future track increases after about 48 hours.

Strong southerly flow on the eastern side of Potential Tropical Cyclone 03 will bring very humid air over the southeastern U.S.  The biggest risk is likely to be heavy rain and the potential for floods.  The system will also bring gusty winds and some storm surge to parts of the coast.

Invests 92L, 93L Monitored for Possible Development

Two weather systems designated as Invest 92L and Invest 93L are being monitored for possible development into tropical cyclones.  Invest 92L is a tropical wave that is speeding toward the Windward Islands.  At 2:00 p.m. EDT on Sunday the center of Invest 92L was located at latitude 7.3°N and longitude 49.4°W which put it about 800 miles (1290 km) east-southeast of the Windward Islands.  It was moving toward the west-northwest at 24 m.p.h. (39 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1008 mb.

Invest 93L consists of a broad area of low pressure over the northwestern Caribbean Sea.  At 2:00 p.m. EDT on Sunday the surface center of Invest 93L was located at latitude 19.0°N and longitude 87.1°W which put it about 145 miles (230 km) south of Cancun, Mexico.  It was moving toward the north-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1006 mb.

Invest 92L is a tropical wave and it has not yet develop a well defined surface center.  There is some evidence of cyclonic rotation on visible satellite imagery and there could be a center in the middle levels of the circulation.  Most of the stronger thunderstorms are located north and west of the center.  The are some bands of showers and thunderstorms south and west of the center.  There is some upper level divergence from the thunderstorms north and west of the center, but it is not well developed at the current time.

Invest 92L is in an environment that is moderately favorable to development of a tropical cyclone.  It is moving over water where the Sea Surface Temperature is near 28°C.  It is in a region of rapid easterly flow, but the wind speed is fairly similar at all levels.  So, there is not a lot of vertical wind shear.  The rapid easterly flow could be inhibiting the formation of a well defined center of circulation.  Invest 92L will be in a moderately favorable environment for about another 36 hours.  An upper level trough over the eastern Caribbean Sea will create increased vertical wind shear when Invest 92L reaches that location.  The National Hurricane Center is indicating that there is a 60% probability that Invest 92L will develop into a tropical cyclone during the next two days.

Invest 92L is being steered rapidly toward the west-northwest by a subtropical high north of it.  A fairly quick motion toward the west-northwest is expected to continue for the next few days.  On its anticipated track Invest 92L could be near the Windward Islands by late Monday.  Even it if does not develop into a tropical cyclone, the system will bring gusty winds and locally heavy rain to those islands.

The structure of Invest 93L is much more complicated.  There is a very broad but weak surface low pressure system over the Yucatan peninsula and the center of that low is being used as the center of the Invest.  However, there is a strong mid-level center of circulation near latitude 18.7°N and longitude 82.9°W which is about 115 miles (185 km) west-southwest of Grand Cayman.  Invest 93L is producing winds to near tropical storm force and those winds are occurring in thunderstorms associated with the mid-level circulation.  It is possible that downdrafts in those thunderstorms could transport enough momentum to the surface to generate a new surface center beneath the mid-level center.

Invest 93L is moving in an environment that will be favorable for the development of a tropical cyclone.  An upper level ridge is building between the trough over the eastern Caribbean Sea and another upper level trough over the northwestern Gulf of Mexico.  The trough over the northwestern Gulf is producing strong southwesterly winds which are causing vertical wind shear over the surface low over the Yucatan peninsula.  However, the upper level ridge is producing an area of slower winds over the mid-level center and there is less vertical wind shear there.  In fact, the upper level ridge is enhancing upper level divergence over the mid-level center.  If that continues, surfaces pressure will begin to decrease in that region.  The National Hurricane is indicating that there is a 70% probability of development of a tropical cyclone or a subtropical cyclone during the next two days.

Invest 93L is moving slowly north-northwestward around the western end of the subtropical high over the Atlantic Ocean.  A general north-northwesterly motion is expected to continue for another day or two, but there is some spread in the guidance from the numerical models.  If a cyclone forms from the surface low over the Yucatan peninsula, then the greatest risk would be to the western Gulf of Mexico.  If a new surface center forms farther east under the mid-level center, then there would be a greater risk for the central and eastern Gulf of Mexico.  Interests around the Gulf should monitor Invest 93L.

Two Areas to Watch for Potential Tropical Development

There are two areas to watch for the potential development of a tropical cyclone during the next week.  One location to watch for potential development is the area around the western Caribbean Sea, Yucatan peninsula and southern Gulf of Mexico.  The other area to watch is the tropical Atlantic between Africa and the Lesser Antilles.

Numerical models have been suggesting possible development of an area of low pressure somewhere over the western Caribbean Sea, Yucatan peninsula or southern Gulf of Mexico.  The scenario suggested by the models includes a surge of southerly winds across Central America, which contributes to the spinning up of an area of low pressure.  There are currently strong westerly winds in the upper levels over this area.  The strong vertical wind shear will prevent development of a tropical cyclone in the short term.  An upper level ridge could develop over the area in several days.  If that happens, the wind shear would decrease.  Some runs of the numerical models create a broad, weak area of low pressure, which would primarily be a rain threat for the Yucatan peninsula and nearby regions.  Other models develop a low pressure system that is a little stronger, although those lows also weaken when they move over the Yucatan.  The models generally move the low pressure system northwestward over the southern Gulf of Mexico.  However, there are fairly significant deviations in how far north the low moves once it is in the Gulf.  As of 8:00 p.m. EDT on June 14 the National Hurricane Center was indicating that there was a 30% probability of the development of a tropical cyclone in this area during the next five days.

Some numerical models have also been suggesting potential development of a tropical cyclone near latitude 10°N over the tropical Atlantic Ocean between Africa and the Lesser Antilles.  A tropical wave is interacting with the Intertropical Convergence Zone and there has been a persistent area of showers and thunderstorms.  The disturbance is moving slowly toward the west.  There is some vertical wind shear in this region, but the stronger upper level winds are north of the disturbance.  The disturbance is over water where the Sea Surface Temperature is near 27°C.  It would be unusual to see a tropical cyclone develop over the tropical Atlantic in June, but it has happened at least three times in the past.  As of 8:00 p.m. EDT on June 14 the National Hurricane Center is indicating that there is a 20% probability of the development of a tropical cyclone in this region during the next five days.

Tropical Storm Beatriz Brings Heavy Rain to Southern Mexico

Tropical Depression Two-E intensified into Tropical Storm Beatriz on Thursday and Beatriz brought heavy rain to parts of southern Mexico.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Beatriz was located at latitude 15.5°N and longitude 96.8°W which put it about 25 miles (40 km) southwest of Puerto Angel, Mexico.  Beatriz was moving toward the north-northeast at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1004 mb.  A Tropical Storm Warning was in effect for the portion of the coast from Salina Cruz to Puerto Escondido.

Tropical Depression Two-E intensified into Tropical Storm Beatriz on Thursday even though its structure evolved into a more asymmetrical system.  Tropical Storm Beatriz appeared to consist of a larger low pressure system which was centered just off the coast of Mexico.  The weather radar from Puerto Angel confirmed that the center of circulation was still offshore.  There were several smaller (mesoscale) counterclockwise rotating circulations that were revolving around the center of the larger low.  At least one of the smaller circulations was already over southern Mexico.  Many of the thunderstorms were occurring in a broad band that wrapped around the eastern and northern portions of the larger low pressure system.  The strongest winds were occurring within this primary rainband.  There were far fewer thunderstorms in the western half of the circulation.  It seemed that after air descended from mountains in Mexico then the air was drawn into the western side of Tropical Storm Beatriz.  The warmer drier air was inhibiting the formation of thunderstorms in the western half of Beatriz.

Although Tropical Storm Beatriz is over water where the Sea Surface Temperature is near 30°C, other environmental factors are unfavorable for intensification.  The proximity to land and the apparent ingestion of drier air are both negative factors.  A narrow upper level ridge oriented from the south-southwest to the north-northeast and a upper level trough to the west of Beatriz are producing brisk southerly winds that are blowing toward the top of the circulation.  Those upper level winds are causing moderate vertical wind shear.  Therefore, Tropical Storm Beatriz is unlike to intensify further during the next several days.

The future track of Tropical Storm Beatriz is uncertain.  If the circulation of Beatriz remains intact then the upper level trough and upper level ridge are likely to steer it toward the north-northeast.  Tropical Storm Beatriz would dissipate over the mountains of Mexico if that scenario occurs.  If the upper level winds are strong enough, the vertical shear could detach the upper portion of the circulation from the low level circulation.  That scenario sometimes occurs when slow moving storms approach the south coast of Mexico.  If that happens, the upper half of the circulation could be transported across Mexico and move over the southern Gulf of Mexico.  Some models are suggesting that a new surface low could form over the southern Gulf in several days, but the wind shear would have to decrease in order for that to occur.  The lower level circulation could be left behind near the coast of Mexico where it would drift slowly near the coast.

Tropical Storm Beatriz is bringing heavy rains to parts of southern Mexico and the heavy rain will continue to fall on Friday.  Locally heavy rain in the more mountainous portions of Oaxaca could create the potential for dangerous flash floods.

Tropical Depressions Form South of Key West & Southeast of Cape Hatteras

Two tropical depressions formed near the U.S. on Sunday.  Tropical Depression Nine formed south of Key West, Florida and Tropical Depression Eight formed southeast of Cape Hatteras, North Carolina.  Both depressions could have an impact on the U.S., but Tropical Depression Nine could pose a greater risk to the southeastern U.S.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Nine was located at latitude 23.7°N and longitude 81.7°W which put it about 60 miles (95 km) south of Key West, Florida.  It was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1009 mb.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Eight was located at latitude 31.8°N and longitude 70.9°W which put it about 355 miles (570 km) southeast of Cape Hatteras, North Carolina.  It was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1010 mb.

The circulation of Tropical Depression Nine is still organizing.  A NOAA plane found a distinct center of circulation, but most of the stronger thunderstorms are south and east of the center.  There is a broader counterclockwise rotation with numerous showers and thunderstorms indicated by the National Weather Service radar in Key West.  An upper level low east of Florida is contributing to easterly winds that are blowing across the northern side of the depression.  The vertical wind shear is inhibiting the development of thunderstorms north and west of the center.

The circulation of Tropical Depression Eight was more well organized earlier today.  Strong easterly winds from the same upper level low that is affecting Tropical Depression Nine are creating significant vertical wind shear.  Those winds and the shear they caused blew the upper portion of the depression’s circulation west of the low level center of circulation.  The low level circulation is presently exposed as seen on visible satellite imagery and by an Air Force Reserve Hurricane Hunter aircraft.

The intensity forecast for Tropical Depression Nine is challenging because it is moving through a complex environment.  The depression is moving over water where the Sea Surface Temperature is near 31°C.  So, there is plenty of energy in the upper ocean.  However, as mentioned above, an upper low is causing vertical wind shear which will inhibit intensification.  Tropical Depression Nine could move into a region where there is less shear when it moves over the Gulf of Mexico.  Tropical Depression Nine has a good chance to intensify into a tropical storm, but it is unclear if it could become a hurricane before it reaches the coast.

There is also significant uncertainty in the track forecast for Tropical Depression Nine.  A ridge over the southeastern U.S. is steering the depression toward the west and that general motion should continue for several more days.  The ridge is forecast to weaken during the middle of the week and that should allow Tropical Depression Nine to turn toward the north.  The timing of that turn and how sharp it will be are still uncertain.

The upper low is expected to continue to generate wind shear over Tropical Depression Eight.  If the upper levels winds remain as strong as they are now, the depression will slowly weaken.  If the upper level winds weaken, then Tropical Depression Eight could strengthen into a minimal tropical storm.  The upper level low is steering the depression west and that general motion is expected to continue in the short term.  The depression could stall just off the coast of North Carolina.

Tropical Depression Nine could intensify and bring wind and rain to the Gulf Coast later this week.  The Gulf Coast is also vulnerable to storm surges.  Given the uncertainty in both the track and intensity, interests along the coast should monitor official sources of information for updates on Tropical Depression Nine.  The primary effects of Tropical Depression Eight are likely to be higher than normal surf, rip currents and some beach erosion along the North Carolina coast.  People along the Mid-Atlantic coast should pay attention to the depression in case the forecast changes.

Tropical Storm Earl Strengthens Near Veracruz

Tropical Storm Earl regained strength on Friday after the center moved over the southern Bay of Campeche near Veracruz, Mexico.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Earl was located at latitude 18.8°N and longitude 95.0°W which put it about 85 miles (135 km) east-southeast of Veracruz, Mexico.  Earl was moving toward the west at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 70 m.p.h. (115 km/h).  The minimum surface pressure was 1001 mb.

Because Tropical Storm Earl re-intensified and the radius of tropical storm force winds expanded to the north, the government of Mexico extended Tropical Storm Warnings farther north along the coast.  A Tropical Storm Warning is in effect for the portion of the coast from Puerto Dos Bocas to Tecolutla, Mexico.

Most of the circulation of Tropical Storm Earl remained intact while it moved over land from Belize to the Bay of Campeche.  As a result, the surface part of the circulation on the northern side of Earl began to redevelop quickly as the center approached the water in the Bay of Campeche.  A primary rainband wrapped most of the way around the center of circulation and other rainbands reformed over the Bay of Campeche.  There have been hints on an incipient eye forming at the center of circulation on recent visible satellite images.  Earl is a very well organized tropical storm.

The Sea Surface Temperature is near 30°C in the southern Bay of Campeche.  The upper level winds are weak and there is little vertical wind shear.  Upper level divergence is well formed in Tropical Storm Earl and it is pumping out mass.  The environment is favorable for further intensification.  However, the center of circulation is close to the coast and approximately 40% of the circulation is over land.  So, the proximity to land is the main factor inhibiting further strengthening.  Tropical Storm Earl does have a few hours to intensify and it could get stronger.

A subtropical ridge north of Earl is steering the tropical storm toward the west and that general motion is expected to continue.  On its anticipated track the center of Tropical Storm Earl will be very near Veracruz, Mexico in 10-12 hours.

The winds in Tropical Storm Earl are strong enough to create a storm surge of several feet (1-2 m) near where the center makes landfall and north of that location.  The primary risks from Tropical Storm Earl will be very heavy rainfall and flash flooding.

Earl Becomes a Hurricane As It Moves Toward Belize

A NOAA aircraft investigating Tropical Storm Earl found that there were sustained winds to hurricane force and the National Hurricane Center upgrade it to Hurricane Earl at 5:00 p.m. EDT on Wednesday.  At 5:00 p.m EDT the center of Hurricane Earl was located at latitude 17.1°N and longitude 86.0°W which put it about 150 miles (240 km) east of Belize City, Belize.  Earl was moving slightly north of due west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 988 mb.

A Hurricane Warning is in effect for the Bay Islands of Honduras and the portion of the coast from Puerto Costa Mayo, Mexico to the Belize/Guatemala border.  A Tropical Storm Warning is in effect for the coast of Honduras from Cabo Gracias a Dios to the Honduras/Guatemala border and from Punta Allen, Mexico to Puerto Costa Mayo.

The Hurricane Intensity Index (HII) for Earl is 10.4.  The Hurricane Size Index (HSI) is 8.0 and the Hurricane Intensity Size Index (HWISI) is 18.4.  Those indices mean that Earl is capable of causing localized minor wind damage.

The structure of Hurricane Earl improved significantly on Wednesday as it moved farther from the northern coast of Honduras.  An eye developed at the center of circulation and a band of thunderstorms wrapped about two thirds of the way around the eye.  The eyewall is broken southwest of the center.  Additional bands of thunderstorms are rotating around the periphery of the circulation.  The core of strongest winds is relatively small and only extends about 60 miles (95 km) from the center.  However, outer rainbands extend at least 250 miles (400 km) from the center of circulation and the overall size of Hurricane Earl is much larger than it was yesterday.

Hurricane Earl is moving through an environment that is favorable for further intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  It is located beneath an upper level ridge and the upper level winds are weak.  So, there is little vertical wind shear and the ridge is enhancing the upper level divergence.  Hurricane Earl has another 10 – 15 hours to intensify before it reaches the coast.  Earl will weaken as it moves inland, but it could re-intensify after it moves over the Bay of Campeche.  The amount of re-intensification will depend on how long Hurricane Earl remains over land and where it enters the Bay of Campeche.

A subtropical high pressure system is steering Hurricane Earl on a track that is a little north of due west and that general motion is expected to continue for several more days.  On its anticipated track the center of Hurricane Earl will reach the coast near the border between Mexico and Belize in about 10 – 15 hours.

Since it is a hurricane, Earl will be capable of causing some wind damage.  Hurricane Earl will also create a storm surge near and to the north of where the center makes landfall because the winds will be pushing water toward the coast.  The size and number of the rainbands in Hurricane Earl will create the potential for very heavy rainfall and serious flooding as it moves inland over Belize and Mexico.

TD 4 Intensifies to Tropical Storm Danielle As It Nears Mexico

A large area of thunderstorms developed near the center of Tropical Depression 4 during during the overnight hours.  An Air Force Reserve Hurricane Hunter reconnaissance aircraft found sustained winds to tropical storm force and at 8:00 a.m. EDT on Monday the National Hurricane Center classified the system as Tropical Storm Danielle.

At 8:00 a.m. EDT on Monday the center of Tropical Storm Danielle was located at latitude 20.6°N and longitude 96.0°W which put it about 95 miles (150 km) east-southeast of Tuxpan, Mexico.  Danielle was moving toward the west-northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1008 mb.  The government of Mexico has issued a Tropical Storm warning for the portion of the coast from Laguna Verde to Rio Panuco.

The center of an upper level ridge moved near the center of Danielle on Sunday night, which caused the upper level winds to be weaker over the core of the circulation.  As a result, a large area of thunderstorms was able to develop and persist around the center of circulation.  Since Danielle was over water where the Sea Surface Temperature was near 30°C, the circulation was able to extract energy from the ocean and Danielle intensified into a tropical storm.

The thunderstorms at the core of Danielle are generating upper level divergence that is pumping mass out in all direction.  The pressure at the surface is likely to decrease which should produce an additional increase in the wind speed.  Danielle will be over very warm water until it makes landfall on the coast of Mexico later today.  It is likely to intensify further before it reaches the coast.

An ridge of high pressure extends from the Atlantic Ocean into the Gulf of Mexico.  The ridge is steering Danielle toward the west-northwest and that general motion is expected to continue.  On its anticipated track the center of Danielle could be very near Tuxpan on the coast of Mexico in about 12 hours.  Danielle could produce a storm surge of several feet along the coast.  It could also cause some wind damage, although that should be minimal.  The increase in thunderstorms near the center of circulation means that Danielle will produce locally heavy rain when it moves inland.  The heavy rain will create the risk of flash floods and mudslides on steeper slopes.

Danielle was designated a tropical storm on June 20, which makes it the fourth Atlantic tropical storm of 2016.  June 20th is the earliest date on record on which the fourth Atlantic tropical storm has formed.  The previous record was June 23, which was the date when Tropical Storm Debbie was named in 2012.   During the record setting year of 2005, the fourth Atlantic tropical storm was not named until July 5.

Tropical Depression 4 Forms Over Bay of Campeche

An Air Force Reserve Hurricane Hunter aircraft investigated an area of low pressure over the Bay of Campeche on Sunday afternoon and found that there was sufficient organization for the National Hurricane Center to designate the system Tropical Depression 4.  At 11:00 p.m. EDT on Sunday the center of Tropical Depression 4 (TD4) was located at latitude 20.1°N and longitude 95.4°W which put it about 145 miles (230 km) east-southeast of Tuxpan, Mexico.  TD4 was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1009 mb.  The government of Mexico has issued a Tropical Storm Warning for the portion of the coast from Laguna Verde to Rio Panuco.

Although the reconnaissance aircraft found that the circulation was better organized than it was on Saturday, it still is not well organized.  There is a distinct center of circulation, but the thunderstorms near the center have been developing and then weakening.  The circulation appears to be somewhat elongated and stretches from the southeast toward the northwest.  A persistent rain band is east and north of the center of circulation and some of the stronger winds are occurring in the rainband.  A new cluster of thunderstorms appears to be developing near the center, and it could represent an improvement in the organization of the depression.

The environment is marginally favorable for intensification.  Tropical Depression 4 is over water where the Sea Surface Temperature is near 30°C.  An upper level ridge is producing some vertical wind shear, but the upper level ridge is also enhancing upper level divergence to the east of the depression.  The depression is close to tropical storm intensity and it has another 12-18 hours to intensify before it makes landfall in Mexico.

A ridge of high pressure that extends from the Atlantic Ocean over the Gulf of Mexico is steering the depression toward the west and that general steering motion is expected to continue.  On its anticipated track, Tropical Depression 4 will make landfall in Mexico on Monday.  The depression could produce locally heavy rainfall and flash flooding will be the primary risk when it makes landfall.

Invest 94L Moves Over Southern Bay of Campeche

A tropical disturbance designated as Invest 94L moved out over the southern Bay of Campeche on Saturday morning.  At 2:00 p.m. EDT on Saturday the center of Invest 94L was located at latitude 19.0°N and longitude 91.8°W which put it about 20 miles (35 km) northeast of Ciudad del Carmen, Mexico.  Invest 94L was moving toward the west-northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 35 m.p.h. (55 km/h).  The minimum surface pressure was 1010 mb.  The National Hurricane Center is putting the probability of development of a tropical cyclone at 50%.  A reconnaissance plane has tentatively been tasked to investigate the system on Sunday afternoon, if necessary.

There is a broad area of lower pressure centered over the extreme southern Bay of Campeche.  However, there is no well formed core at the center of the circulation.  In addition there are only thin fragmented lines of showers and thunderstorms instead of well formed spiral bands.  The circulation seems to exist primarily in the lower portion of the atmosphere.  An upper level ridge east of Invest 94L is providing some upper level divergence.

The center of Invest 94L has moved over water and the Sea Surface Temperatures in the southern Bay of Campeche are 30°C – 31°C.  So there is plenty of energy in the upper ocean to support tropical development.  However, the western side of the upper level ridge is causing southerly winds to blow over the top of Invest 94L which is creating vertical wind shear.  The southern portion of the circulation is still over land, which is also an inhibiting factor.  The combination of positive and negative environmental factors are contributing to the uncertainty over the possible development of Invest 94L.

Invest 94L is being steered toward the west-northwest by a ridge of high pressure to its northeast.  On its anticipated track, the center of Invest 94L will remain over water for another 24 to 48 hours.  That time period represents the window during which Invest 94L could develop into a tropical depression or a tropical storm.  Invest 94L is likely to reach the coast of Mexico in about two days and when it moves inland, the chance for development will end.