*******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...THURSDAY AUGUST 29 2024 10:25 AM EDT...
Surface and upper air charts have now been added to the satellite image associated with this post. The charts were not originally included in this update to allow the update to be released in a timely manner.
...WEDNESDAY AUGUST 28 2024 5:00 PM EDT...
Atlantic tropical activity is increasing with the presence of multiple hot spots as follows:
(1) In the western Gulf of Mexico... thunderstorms continue to increase in association with the eastern divergence zone of the upper vortex over Texas... however the CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) shows no low-level low pressure spin has developed so far to declare an area of interest for tropical development... and computer models are not forecasting development here. However heavy rainfall is possible across coastal regions of Texas and Louisiana over the next couple of days.
(2) The tropical low pressure swirl that saw an increase in thunderstorm overnight... located well southeast of Bermuda... was upgraded by the NHC to an area of interest for possible development... see area of interest #20 section below for more information.
(3) The eastern Atlantic tropical wave... tagged as area of interest #19 in this update... has lost the thunderstorm activity it developed last night. See area of interest #19 section below for more information on this tropical wave.
(4) Satellite imagery suggests another vigorous tropical wave of low pressure is currently approaching the west coast of Africa... this feature will move offshore shortly while potentially taking advantage of an expanding tropical upper ridge axis (environment of low shear and upper outflow)... see area of interest #21 section below for more information.
AREA OF INTEREST #19... The tropical wave of low pressure in the eastern tropical Atlantic saw an increase in thunderstorm activity during the overnight hours... but throughout today the thunderstorm activity has dwindled perhaps due to the surge of dry Saharan air pushing southwest toward the wave and kicked up by the adjacent western Africa tropical wave to the east (area of interest #21). For the updated outlook below this system is initialized at 11.2N-34.5W... where the cyclonic curvature of the remainder cloudiness in the wake of the dwindled thunderstorms suggests a center of rotation as of 1800Z earlier this afternoon. Going forward... the tropical wave still has a window to develop while continuing west where concentrations of dry Saharan air tend to be lower... and as the adjacent string of upper vorticity continues to shift west and away while pushed by the central Atlantic mid-latitude upper ridge... allowing tropical upper ridging (environment of low shear and outflow) to expand in the wake of the upper vorticity string and over the tropical wave. By the end of the 5-day forecast period the central Atlantic mid-latitude upper ridge becomes replaced by an upper ridge north of the Caribbean Islands that expands in the wake of the retreating current northwest Atlantic upper trough... with the replacement mid-latitude upper ridge blocking westward progress of the upper vorticity string. In turn this allows this tropical wave to catch up to the upper vorticity string toward day 5 which is why my track forecast toward that time has an increased north slant... especially if this system becomes stronger/taller to be pulled by the flow on the east side of the upper vorticity string. The catch-up to the upper vorticity string may actually be a negative for development due to the associated shearing upper winds... therefore given the recent loss of thunderstorms... loss of computer model support showing development... and increasingly likely shear towards day 5 I have lowered my odds of tropical cyclone formation for this system to a peak of 15%.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 29)... 0% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-38.5W)
IOH 48 Hr Outlook (1800Z Aug 30)... 5% chance of tropical cyclone formation (central tropical Atlantic near 11.5N-43W)
IOH 72 Hr Outlook (1800Z Aug 31)... 15% chance of tropical cyclone formation (central tropical Atlantic near 12N-48.5W)
IOH 96 Hr Outlook (1800Z Sep 1)... 15% chance of tropical cyclone formation (central tropical Atlantic near 13N-52W)
IOH 120 Hr Outlook (1800Z Sep 2)... 15% chance of tropical cyclone formation (east of the Lesser Antilles near 13.5N-56W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 2 PM EDT***************************
Formation chance through 48 hours... 0%
Formation chance through 7 days... 20%
AREA OF INTEREST #20... Satellite image of tropical low pressure southeast of Bermuda when it featured a strong burst of thunderstorms earlier today... at 0300Z:
A large tropical wave of low pressure emerged from the coast of Mauritania on August 19... since then the north side of the tropical wave separated from the rest of the wave as a surface trough of low pressure that has continued west across the mid-latitudes of the Atlantic. As of August 26 the surface trough appeared to evolve into a surface low... and overnight (last evening) the small surface low pressure swirl while located well southeast of Bermuda saw an increase in thunderstorm bursts while interacting with the boosting divergence zone of the current northwest Atlantic upper trough. This prompted the National Hurricane Center by 2 AM EDT to upgrade the small tropical low into an area of interest for possible tropical cyclone formation... this will mark the twentieth tropical area of interest tracked on this site this year.
The tropical low has been coaxed into a slow northward turn by the surface ridge weakness associated with the pair of surface frontal lows that are currently east and south of Newfoundland... this track has taken the tropical low into increasingly hostile westerly shear imparted by the current northwest Atlantic upper trough... with the shear already separating last night's thunderstorms away from the surface center with no new thunderstorms developing near the center since then. Over the next couple of days the tropical low is expected to undergo a northeast drift while chasing the surface ridge weakness associated with the eastward-shifting surface front that is now approaching from the Great Lakes region of North America... and a one-two punch of westerly shear from the current northwest Atlantic upper trough and a second upper trough that moves into the northwest Atlantic from its current east Canada position is expected to inhibit tropical cyclone formation. This is why tropical cyclone formation odds are currently set to 0%. The long range outlook beyond 48 hours looks interesting if the tropical low can survive the short-term shear. During this time whatever is left of the tropical low would turn northwest into the open northwestern Atlantic waters as the current central Canada surface ridge passes to its north and steers it. In the upper-levels the current upper trough near the Minnesota/Canada border slows down its eastward travel and amplifies into a northwest Atlantic upper vortex due to adjacent amplification of upstream upper ridging over eastern North America in the warm sector of a currently-forecast vigorous Canadian frontal cyclone. In the northwest Atlantic... shear would drop over what would be the remainder of the tropical low while the eastern divergence zone of the upper vortex potentially enhances its thunderstorms. For now this will be my first and final outlook (with track forecast and probabilities of cyclone formation) on this area of interest as I anticipate the NHC dropping this area of interest from their outlook soon... however if this system lingers after the short-term wind shear may consider re-upgrading it to an area of interest for the open northwest Atlantic in future updates.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 29)... 0% chance of tropical cyclone formation (central Atlantic near 32N-59W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 2 PM EDT***************************
Formation chance through 48 hours... 0%
Formation chance through 7 days... 0%
AREA OF INTEREST #21... A vigorous tropical wave of low pressure approaching the west coast of Africa... featuring widespread vigorous thunderstorm activity and located in the vicinity of 10N-12W as of 1800Z earlier this afternoon... has potential to develop underneath the same expanding tropical upper ridge axis that area of interest #19 off to the west may take advantage of. The usually conservative ECMWF model was picking up on this as of this past 0000Z run... therefore I have upgraded the tropical wave to another area of interest for possible tropical development in the Atlantic basin... the twenty-first such area of interest tracked on this site this year. I have already started with a peak 20% odds of tropical cyclone formation due to the current vigor of the wave... and have not assigned higher odds at this time while not all models agree on developing this wave. The 20% odds are weighted toward day 5 instead of the short-term to give time for the wave to move away from higher concentrations of dry Saharan air toward the east part of the Atlantic basin... and to give time for the wave to become better-organized (while the wave features abundant thunderstorm activity... the activity is blobbed in appearance rather than having bands with cyclonic curvature).
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 29)... 0% chance of tropical cyclone formation (just offshore of the west coast of Africa near 10N-17W
IOH 48 Hr Outlook (1800Z Aug 30)... 0% chance of tropical cyclone formation (southeast of the Republic of Cabo Verde Islands near 10.5N-21W)
IOH 72 Hr Outlook (1800Z Aug 31)... 10% chance of tropical cyclone formation (south-southwest of the Republic of Cabo Verde Islands near 11N-25W)
IOH 96 Hr Outlook (1800Z Sep 1)... 20% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-29.5W)
IOH 120 Hr Outlook (1800Z Sep 2)... 20% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-33.5W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 2 PM EDT***************************
Not in the official outlook
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Aug 28) CMC Model Run...
**For area of interest #19... no development shown
**For area of interest #20... no development shown
**For area of interest #21... no development shown
0000Z (Aug 28) ECMWF Model Run...
**For area of interest #19... no development shown
**For area of interest #20... no development shown
**For area of interest #21... tropical wave currently approaching west coast of Africa moves offshore at 42 hours and passes just south of the Republic of Cabo Verde Islands at 102 hours as a broad tropical low... broad tropical low reaches 14N-35W by 168 hours
1200Z (Aug 28) GFS Model Run...
**For area of interest #19... no development shown
**For area of interest #20... no development shown
**For area of interest #21... no development shown
0600Z (Aug 28) NAVGEM Model Run...
**For area of interest #19... no development shown
**For area of interest #20... no development shown
**For area of interest #21... Tropical wave currently approaching west coast of Africa slowly moves offshore and evolves into a broad tropical low that passes just south of the Republic of Cabo Verde Islands through 168 hours
Comments