*******Note that forecast and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.*********
...UPDATE...WEDNESDAY JUNE 19 2024 8:40 PM EDT...
Colorized infrared satellite imagery as the broad tropical low pressure area in the Bay of Campeche and western Gulf of Mexico... tagged as area of interest #5 in this blog post... intensified into Tropical Storm Alberto:
The south side of the broad tropical low pressure area spanning the Bay of Campeche and western Gulf of Mexico proceeded to fire concentrated thunderstorm activity this morning... and by 11 AM EDT the latent heat release warm core upper outflow generated by the thunderstorm activity caused a well-defined 995 mb surface low pressure center to form toward the south and within the broad circulation. As a result this system was promptly upgraded to Tropical Storm Alberto. Despite this low of a pressure... maximum sustained winds only remain 40 mph as the 995 mb center remains in a broad low pressure field... thus is there is less wind-driving pressure gradient from the center to outer edge of the circulation. The southward relocation of the best-defined center is allowing tropical storm force conditions (gusty winds and coastal surf) to spread onshore as far south as northern Veracruz... while these conditions continue spreading onshore across coastal Tamaulipas and southern Texas. See area of interest #5 section in the full update below... and the official NHC website (www.nhc.noaa.gov) for more information regarding what is now Tropical Storm Alberto.
...WEDNESDAY JUNE 19 2024 1:55 AM EDT...
The Atlantic tropics remain busy for mid-June while still monitoring three concurrent areas of interest as follows:
See area of interest #5 section below for an update on the large gyre of low pressure currently covering the western Gulf of Mexico and Bay of Campeche and now heading for northeastern Mexico and southern Texas. See area of interest #7 section below for another gyre that could materialize over the Caribbean and Central America... and head toward the Gulf of Mexico in the immediate wake of area of interest #5. Together... both gyres are forecast to produce a dangerously extended period of heavy rainfall across western Central America and eastern Mexico over the next several days.
See area of interest #6 section below for an update on the current western Atlantic surface trough of low pressure. This disturbance is forecast to shift west toward the northwestern Bahamas and southeastern United States coastal region by Friday and Saturday.
Elsewhere... a vigorous tropical wave of low pressure featuring rotating thunderstorm activity has emerged from the west coast of Africa while underneath favorable low shear and outflow beneath regional tropical upper ridging. However the northwest side of the wave is ingesting dry Saharan air and tropical development of this wave is not forecast.
AREA OF INTEREST #5 (POTENTIAL TROPICAL CYCLONE ONE)... The broad tropical low pressure over the Bay of Campeche has expanded northward across the western Gulf of Mexico over the last 24 hours... likely due to the eastern divergence zone of the recently-dissipated central US upper trough which extended into the northwestern Gulf of Mexico and dropped surface pressures in that region. This has resulted in a northward shift in the centroid of the broad surface low and my updated forecast track is adjusted accordingly. The forecast track angle is generally west-northwest toward the surface ridge weakness associated with the current central US surface front... with the front and its upper trough not able to fully curve the track of this system north while lifting quickly to the northeast and away (while failing to defeat the current eastern North America heat wave upper ridge). Instead the surface ridge that then builds behind the front finishes the job by continuing to push this area of interest west-northwest into northeastern Mexico by 48+ hours. Regarding odds of tropical cyclone formation... sea surface temps are rather warm and this system is forecast to remain under low shear and outflow beneath upper ridging all the way until it makes landfall with northeastern Mexico. An additional bonus is that this system continues to have signs of organization while having peripherial curved thunderstorm bands in all quadrants of the circulation. While I continue to agree with the NHC in having high odds of tropical cyclone formation (above 50%)... I have begun to taper down my peak odds of development as most of the model runs in the last couple of days suggest this system never develops a well-defined surface center necessary for tropical storm status... and this system is not making progress in developing further while failing to produce a thunderstorm core in the region of its centroid that would help generate a well-defined center.
Regardless of whether or not this area of interest develops into a tropical cyclone... the impacts to land areas will remain the same. The pressure gradient between steering surface ridging to the north and this system's surface low pressure field will cause gusty winds and coastal surf to push into southern Texas and Tamaulipas through 48 hours. Due to the aforementioned northward expansion of this system... gusty winds are possible as far north as San Luis Pass Texas where the NHC recently expanded tropical storm warnings to (meanwhile the potential for gusty winds for Veracruz has reduced due to the northward shift of the forecast track combined with the fact this system is not developing a more conventional center with central wind field). The rainfall flooding risk remains for much of eastern Mexico... and has recently expanded northward into southern Texas given the aforementioned northward expansion of this system. Note this region may not be done with inclement weather conditions after this area of interest moves into northeastern Mexico as another disturbance potentially develops in its wake... see area of interest #7 section below for more information.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Jun 20)... 70% chance of tropical cyclone formation (offshore of northern Veracruz near 23N-96W)
IOH 48 Hr Outlook (0000Z Jun 21)... 70% chance of tropical cyclone formation (Tamaulipas Gulf coast near 24N-98W)
IOH 72 Hr Outlook (0000Z Jun 22)... 0% chance of tropical cyclone formation (interior northeastern Mexico near 25N-100W)
******National Hurricane Center (hurricanes.gov) official forecast as of 11 PM EDT***************************
Peak Strength (0000Z Jun 20)... 45 maximum sustained wind tropical storm centered offshore of northeastern Mexico at 22.8N-96.3W
Landfall (1200Z Jun 20)... 40 mph maximum sustained wind tropical storm centered over southern Tamaulipas at 22.9N-98.5W
Dissipation (0000Z Jun 21)... 25 mph maximum sustained wind dissipating remnant low centered over interior northeastern Mexico at 23N-100.5W
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT***************************
Formation chance through 48 hours... 80%
Formation chance through 7 days... 80%
AREA OF INTEREST #6... The western Atlantic surface trough positioned between the northern Caribbean Islands and Bermuda persists due to an area of upper divergence on the east side of a large upper vortex in the region. Global models have been moving away from developing the surface trough while forecasting the trough to move into the northeast part of the upper vortex where supportive upper divergence is lacking. This has not happened yet as the surface trough has not moved much to the west... instead is currently located in the vicinity of 26N-66W. Despite still being in an upper divergence environment... the surface trough and its associated showers and thunderstorms have shown signs of weakening. During the forecast period the regional upper vortex is forecast to retrograde west-southwest around the SW/NE tilted eastern North America upper ridge while at the same time the surface trough moves west-northwest toward the northwestern Bahamas and southeastern US coastline while pushed by the NW/SE tilted surface ridge currently in the northwest Atlantic... followed by the next NW/SE tilted surface ridge that quickly fills in behind the current central US frontal system. Despite the more east initial position of the surface trough... the models more quickly move the trough to the west-northwest as it is already weaker (lower in amplitude) such that it can more easily flow around the aforementioned surface ridges... thus my updated track forecast below is similar to the previous as the faster forward speed allows this system to catch up to the previous forecast points. I carry 0% odds of tropical cyclone formation through 24 hours as the track moves this system underneath the suppressive northeast quadrant of the regional upper vortex. Due to the different tilt angles of the upper vortex and surface trough trajectories... the surface trough escapes the upper vortex by 48 and 72 hours. However I show low 10% odds of tropical cyclone formation as any breathing room in the upper-levels will be small as another upper vortex (originating as a piece of energy ejecting southwestward from the current north Atlantic upper trough) encroaches from the northeast. Forecast track after 72 hours is for more of a northward turn in the flow ahead of the next frontal system in the mid-latitude westerlies that approahces from western North America... and I drop odds of tropical cyclone formation to 0% for 96+ hours as the track increases land interaction with the southeastern US... especially as the the second suppressing upper vortex from the northeast moves in over this system.
Given the above-discussed and dynamic and uncertain upper wind forecast... there is an equal probability that this system brings heavy rainfall to the northwestern Bahamas and parts of the coastal southeastern United States by Friday and this weekend... and also an equal probability that the impacts from this system to land areas could end up being negligble. Interests in this region can check back for the latest forecast on this area of interest in future updates.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Jun 20)... 0% chance of tropical cyclone formation (western Atlantic near 27N-71W)
IOH 48 Hr Outlook (0000Z Jun 21)... 10% chance of tropical cyclone formation (east-northeast of the northwestern Bahamas near 27.5N-76W)
IOH 72 Hr Outlook (0000Z Jun 22)... 10% chance of tropical cyclone formation (offshore of northeastern Florida near 29N-79W)
IOH 96 Hr Outlook (0000Z Jun 23)... 0% chance of tropical cyclone formation (coastal Georgia near 31.5N-81.5W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT***************************
Formation chance through 48 hours... 10%
Formation chance through 7 days... 20%
AREA OF INTEREST #7... Surface pressures remain generally low across the south-central Caribbean due to a developing area of split flow upper divergence between the southwest side of the upper vortex tied to area of interest (AOI) #6 and southeast side of the expansive eastern North America upper ridge. As the upper vortex retrogrades southwestward around the upper ridge and through the region... divergence zones around its periphery are forecast to produce another gyre of low surface pressures that generally chases AOI #5. My forecast track for this area of interest is generally west-northwest from the central Caribbean and into the Yucatan peninsula through day 4 while steered by the same surface ridges that steer AOI #6. Note that by day 5 I slow the forecast track speed and apply a northward bend toward the surface ridge weakness associated with a series of frontal systems to push in from western North America. The slow speed is due to the frontal systems being forecast to pass well north of this area of interest. Through 24 hours my forecast position aligns with the aforementioned supportive split flow upper divergence on the southwest side of the incoming upper vortex... however northerly shear will be excessive for tropical development and I have 0% development odds during that window. By 48+ hours the upper vortex accelerates westward and away while weakening from its prolonged isolation from high-latitude cold air... this results in this area of interest being enhanced by the southeastern divergence zone of the departing upper vortex at 48 hours but with excess southerly wind shear such that I still show 0% chance of tropical cyclone formation. The shear relaxes and anticyclonic outflow over this disturbance expands once the decaying upper vortex finishes moving away... and by 72 hours is when I show odds of development above 0%. However my development odds are at a low 10% as this system would have a narrow window to develop as the upper winds become favorable only right before landfall with Belize or the Yucatan peninsula of Mexico. By day 5... as this system works its way into the Gulf of Mexico from the Yucatan... there is a second small upper vortex that also surges toward the Gulf of Mexico (see area of interest #6 section above for more info on this second vortex). There is some uncertainty as to how favorable the upper winds would be for this system to develop in the Gulf after day 5 as the southwest side of the vortex could induce some unfavorable westerly wind shear... thus my development odds for day 5 are also at a low 10%.
Regardless of tropical cyclone formation or not... the main takeaway for this area of interest is that it could produce heavy rainfall with flash flooding potential across western Central America and southeastern Mexico in the days ahead. The flooding risk here is enhanced as area of interest #5 recently saturated the grounds in this region.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Jun 20)... 0% chance of tropical cyclone formation (Caribbean Central America coast at Nicaragua/Honduras border near 15N-83.5W)
IOH 48 Hr Outlook (0000Z Jun 21)... 0% chance of tropical cyclone formation (western Caribbean and offshore of northeastern Honduras near 16.5N-85W)
IOH 72 Hr Outlook (0000Z Jun 22)... 10% chance of tropical cyclone formation (western Caribbean and offshore of southern Quintana Roo near 18N-86.8W)
IOH 96 Hr Outlook (0000Z Jun 23)... 0% chance of tropical cyclone formation (southern Yucatan peninsula near 19N-89W)
IOH 120 Hr Outlook (0000Z Jun 24)... 10% chance of tropical cyclone formation (northwestern Yucatan peninsula coast near 20.5N-90.5W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT***************************
Formation chance through 48 hours... 0%
Formation chance through 7 days... 30%
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
1200Z (Jun 18) CMC Model Run...
**For area of interest #5... center of broad tropical low makes landfall over southern Tamaulipas by 42 hours without tropical cyclone formation... rapidly dissipates inland shortly thereafter
**For area of interest #6... no development shown
**For area of interest #7... Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #5 (42 to 66 hours)... consolidates into an eastern Bay of Campeche tropical low by 90 hours with tropical cyclone formation suggested as this system makes landfall near the Veracruz/Tamaulipas border by 144 hours... rapidly dissipates inland shortly thereafter
1200Z (Jun 18) ECMWF Model Run...
**For area of interest #5... center of broad tropical low makes landfall near the Tamaulipas/Veracruz border by 42 hours without tropical cyclone formation... rapidly dissipates inland shortly thereafter
**For area of interest #6... no development shown
**For area of interest #7... Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #5 (42 to 66 hours)... Bay of Campeche portion of circulation becomes the dominant through 90 hours... the broad system proceeds northwest across the southwestern Gulf of Mexico and makes landfall just south of the Texas/Mexico border by 144 hours without tropical cyclone formation... rapidly dissipates inland shortly thereafter
1200Z (Jun 18) GFS Model Run...
**Fore area of interest #5... broad tropical low consolidates into a tropical cyclone while making landfall over southern Tamaulipas at 48 hours... rapidly dissipates inland shortly thereafter
**For area of interest #6... no development shown
**For area of interest #7... Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #5 (48 to 63 hours)... through 105 hours the western Bay of Campeche portion of the circulation becomes the dominant... due to surface ridge weakness of a pair of North American frontal systems passing to the north this system turns northwest from the western Bay of Campeche (albiet the northwest track of this system is slow as the frontal systems pass well to the north)... by 168 hours the slow northwest track takes the broad low pressure area into northern Veracruz with no tropical cyclone formation shown prior to the landfall
1200Z (Jun 18) NAVGEM Model Run...
**For area of interest #5... center of broad tropical low makes landfall near the Tamaulipas/Veracruz border by 48 hours without tropical cyclone formation... rapidly dissipates inland shortly thereafter
**For area of interest #6... no development shown
**For area of interest #7... Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #5 (48 to 60 hours)... Bay of Campeche portion of the circulation becomes the dominant with rapid tropical cyclone formation shown near 20.5N-94.5W at 84 hours... tropical cyclone weakens to remnant low while moving northwest into Tamaulipas/Veracruz border through 132 hours and rapidly dissipates inland shortly thereafter
**Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #7 (120 to 138 hours)... due to enhancing split flow upper divergence between southwest side of small upper vortex approaching from northeast and east side of regional tropical upper ridge the western Caribbean portion of the circulation becomes the dominant through 150 hours and proceeds to make landfall on the east coast of the Yucatan peninsula (east-central Quintana Roo) through 168 hours while intensifying further into a tropical cyclone.
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