*******Note that forecasts 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.**********
...TUESDAY AUGUST 30 2022 4:00 AM EDT...
Opportunities for tropical cyclone formation in the Atlantic basin are increasing as we end the month of August due to the following three areas of interest in the tropical latitudes:
(1) See area of interest #20 for more information on a broad but organizing tropical low pressure in the central tropical Atlantic. Note that this system will pass near the northern Lesser Antilles on Thursday and Friday.
(2) See area of interest #22 section below for an update on the disturbance in the western Caribbean Sea. Any feature that develops here is expected to head west-northwest toward western Cuba and the northeastern Yucatan peninsula of Mexico in the days ahead.
(3) A tropical low pressure spin has formed in the far eastern tropical Atlantic just offshore of Senegal from the merger of two tropical waves that were over western Africa. See area of interest #23 section below for more information. Note this disturbance has potential to bring heavy rain and gusty winds to the Republic of Cabo Verde Islands tonight and Wednesday.
In addition... the mid-latitudes of the Atlantic may host tropical development in the days ahead as follows:
(1) See area of interest #24 and #25 sections below for more information on possible open central Atlantic tropical development over the next 48 hours.
(2) The tail end of the surface front currently moving across the central United States...driven by the frontal cyclone currently over central Canada... will enter the western Atlantic from the United States east coast in approximately three days. Although some upper westerly flow will likely be over the tail end of the front... any defined surface low pressure feature that develops along the tail end of the front and offshore of the southeastern United States will likely accelerate northeastward toward the surface ridge weakness to be induced by the remainder of the front. This northeastward acceleration would reduce the effect of upper westerly shear... therefore may have to watch for tropical development along the tail end of the front in the days ahead.
New to this site this year... I will be sequentially numbering up areas of interest for possible Atlantic tropical development. In this scheme... will reset back to #1 at the start of next year (January 2023). The current areas of interest in this blog post are designated #20 through #25 as I designated the other nineteen of this year in previous birdseye view posts on the home page. This scheme is to reduce confusion as Atlantic tropical activity increases during the peak of the hurricane season... when multiple simultaneous areas of interest begin and end which previously required shuffling around the area of interest numbers from update to update.
AREA OF INTEREST #20...The broad tropical low pressure system in the open central Atlantic has undergone a few changes since my previous update on this feature nearly 48 hours ago. Specifically by studying long-term satellite loops... it appears the center of rotation that was near 15N-41W in the previous update fizzled while a new center of rotation currently near 14.5N-47.5W has developed further to the southwest. The dissipating northeastern center may have also played a role in initially tugging the new southwestern center such that it was not able to move as fast to the west. Models in previous days suggested a slow-down in the westward progress of this system perhaps while picking up on this evolution... however without that understanding my previous forecast track had this system moving more quickly westward. The updated forecast track in the outlook below is adjusted as needed and is now more in alignment with the global model consensus. The updated forecast track is advantageous to this system's development potential by not immediately tossing this system into the shear being induced by the nearby upper vorticity to the northwest. However this system in the short-term will still be close enough to the upper vorticity to see some shear... and early evidence of this is shown in the current satellite presentation showing a southwest-northeast elongated area of thunderstorms straddling the current center of rotation while thunderstorms are lacking in the northwest quadrant of the circulation. This explains the shorter-term lower odds of tropical cyclone formation being at 40%... with odds trimmed down to 30% by 72 hours as this system potentially moves closer to the shearing upper vorticity. In the longer-term models agree that the cold core upper vorticity and the associated shear will markedly weaken while remaining cut-off from high-latitude cold air... and this is when the models essentially are now in unanimous agreement on tropical cyclone formation. Therefore by days 4 and 5 my odds of tropical cyclone formation quickly climb to 70% (the NHC as of this writing hads odds of 80% for this timeframe).
Regarding the forecast track... a gradually increasing northward bend in the westward track is anticipated over the next five days as this system rounds the southwestern side of the Atlantic surface ridge. The current central US/Canada frontal system will move into the western Atlantic... and then by day 5 begin to depart northeastward out of the region upon which time a surface ridge is expected to build in its wake. However an ongoing north angle in track is expected as this system is likely to be tall/strong enough to be steered by the fading upper vorticity to the west.
Regarding impact to land areas... this system will pass just northeast of the Lesser Antilles Thursday and Friday. During this time the southwestern quadrant has potential to bring heavy rains... gusty winds... and coastal sea swells... particularly if tropical cyclone formation occurs.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 30)...40% chance of tropical cyclone formation (central tropical Atlantic near 14.5N-52W)
IOH 48 Hr Outlook (1800Z Aug 31)...40% chance of tropical cyclone formation (central tropical Atlantic near 15.5N-56W)
IOH 72 Hr Outlook (1800Z Sep 1)...30% chance of tropical cyclone formation (east of the northern Lesser Antilles near 17.5N-59W)
IOH 96 Hr Outlook (1800Z Sep 2)...50% chance of tropical cyclone formation (just north of the northern Lesser Antilles near 19.5N-62W)
IOH 120 Hr Outlook (1800Z Sep 3)...70% chance of tropical cyclone formation (western Atlantic to the north-northeast of Puerto Rico near 21.5N-65W)
AREA OF INTEREST #22...The surface trough/tropical wave that has been traversing westward across the Caribbean Sea has now moved into Central America. However on Monday afternoon showers and thunderstorms in the western Caribbean markedly increased due to an area of split flow upper divergence between the west side of the upper vortex that has been sliding southwest into the north coast of Haiti and southeast side of Gulf of Mexico upper ridging. Since then the thunderstorm activity has fizzled... however curved low cloud bands remain in the region. The GFS model in prior days... which showed possible western Caribbean development from an upper divergence zone either on the west or east side of the upper vortex... has also stopped showing this solution. As a result the NHC has just recently (as of 2 AM EDT) cancelled this disturbance from its 5-day tropical weather outlook. However for now I am maintaining this disturbance as an area of interest due to the presence of the curved low cloud bands and ongoing upper divergence zone. However I have also delayed the low 10% odds of tropical cyclone formation by 24 hours as whatever vorticity is associated with the curved cloud bands is not near the surface as shown in the CIMSS 850 mb vorticity product (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=)...in other words time is needed for this system to establish surface-level vorticity in the wake of the now departing surface trough/tropical wave.
Any surface vorticity feature that develops is likely to head west-northwest toward the northeastern Yucatan peninsula of Mexico and western Cuba while rounding the southwest side of the Atlantic surface ridge. Once in the southern Gulf of Mexico and by days 4 to 5... the track will likely bend west surface ridging over North America recovers in the wake of the current and subsequent central US/Canada frontal systems... as both systems later shift northeastward and away from the region. As this disturbance moves away from the upper vortex currently near the north coast of Haiti... it will encounter more favorable low shear/upper outflow beneath the current Gulf of Mexico upper ridge by day 3. By day 4 this system will interact with the eastern divergence zone of upper vorticity to be left behind by the current central US/Canada frontal system which may also aid in generating thunderstorm activity. However by day 5 the forecast track places this system under the western convergence zone of the upper vorticity... and this is when I bring odds of tropical cyclone formation to 0%.
Regardless of tropical cyclone formation or not... the northeastern Yucatan and western Cuba may see heavy rainfall from this disturbance on Thursday... especially if it can re-establish thunderstorm activity.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 30)...0% chance of tropical cyclone formation (just southwest of the Cayman Islands near 18N-82W)
IOH 48 Hr Outlook (1800Z Aug 31)...0% chance of tropical cyclone formation (west of the Cayman Islands near 19.5N-84W)
IOH 72 Hr Outlook (1800Z Sep 1)...10% chance of tropical cyclone formation (between the western tip of Cuba and northeastern corner of Yucatan peninsula near 22N-86W)
IOH 96 Hr Outlook (1800Z Sep 2)...10% chance of tropical cyclone formation (southern Gulf of Mexico near 23.5N-88.5W)
IOH 120 Hr Outlook (1800Z Sep 3)...0% chance of tropical cyclone formation (southwestern Gulf of Mexico near 23.5N-92W)
AREA OF INTEREST #23...A tropical low pressure spin has formed in the far eastern tropical Atlantic just offshore of southern Senegal from the merger of two tropical waves that were over western Africa. As of this writing the center of rotation appeared to be near 12.5N-17W with organizing thunderstorm features particularly over and west of the center of rotation. Favoring potential development of this system is the ongoing tropical upper ridge in the region featuring low shear and upper outflow. Computer model support showing development has increased... and in this update I have raised peak 5-day odds of tropical cyclone formation to 60% (also note as of this writing the NHC has increased odds to 40%). Regarding the forecast track... this system is expected to eventually slide west around the south side of the Atlantic surface ridge. However satellite animation shows the tropical low pressure has been generally stationary... a sign that the seedling pair of tropical waves are still finishing the merging process. Therefore the forecast track below shows an initial slower speed... followed by a typical westward forward speed for the tropical latitudes. The forecast track and models take this system very near or over the Republic of Cabo Verde Islands by tonight and Wednesday... gusty winds and heavy rains are possible... especially if tropical cyclone formation occurs in the short-term.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 30)...30% chance of tropical cyclone formation (just offshore of western Africa near 13N-19.5W)
IOH 48 Hr Outlook (1800Z Aug 31)...60% chance of tropical cyclone formation (just south of the Republic of Cabo Verde Islands near 13.5N-23.5W)
IOH 72 Hr Outlook (1800Z Sep 1)...60% chance of tropical cyclone formation (eastern tropical Atlantic near 14.5N-27.5W)
IOH 96 Hr Outlook (1800Z Sep 2)...60% chance of tropical cyclone formation (eastern tropical Atlantic near 15N-32W)
IOH 120 Hr Outlook (1800Z Sep 3)...60% chance of tropical cyclone formation (eastern tropical Atlantic near 15.5N-37W)
AREA OF INTEREST #24...The swirl of low surface pressure that was previously near 32N-54.5W has drifted south to 31N-54.5W... likely by the upper northerly flow induced by the west side of the central Atlantic upper vorticity and south side of the current central Atlantic upper ridge axis. The more south position places the surface low under less favorable northerly wind shear... and also away from the outflow environment beneath the upper ridge axis and also the divergence zone of a cut-off upper vortex currently setting up to the northwest that would have otherwise helped this system. Therefore tropical cyclone formation is no longer possible with this feature... with that potential now lying with the aforementioned upper vortex and stalled front just off to the northwest... see area of interest #25 section below for more information. Meanwhile NHC has removed this feature from its tropical weather outlook... and this is the final statement on this area of interest on this blog.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 30)...0% chance of tropical cyclone formation (central Atlantic near 31.5N-54.5W)
AREA OF INTEREST #25... The current north Atlantic/Greenland upper vortex and its associated surface frontal cyclone have left behind a string of upper vorticity in the northwest Atlantic and a surface stalled front. Over the next 24 hours... models agree that a portion of the stalled front near 35N-55W will evolve into a surface low pressure swirl supported by the eastern divergence zone of a small upper vortex to become established by a chunk of the decaying string of upper vorticity. The CIMSS 850 mb vorticity product (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) is already picking up on an increased area of low-level vorticity along the stalled front that will soon slide east to 35N-55W... and an organizing comma shaped area of showers and thunderstorms coincides with the area of increased 850 mb vorticity. Therefore I already assign 20% odds of subtropical cyclone formation in the short-term. The subtropical designation is used as this system could resemble a hybrid supported in a non-tropical fashion by the divergence zone of the upper vortex... and supported in a tropical fashion by thunderstorm-generated warm core upper outflow that could be established just east of the upper vortex. Between 24 and 48 hours the frontal system currently approaching from the central US/Canada will erode the northwest side of the Atlantic surface ridge... allowing this system to make an escape to the north-northwest and then toward the north. A tropical designation is used at 48 hours as the northward track of the surface low pressure system pulls it away from the upper vortex. Odds of development are dropped to 0% at 72 hours as this system's northward track takes it into cool waters.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 30)...20% chance of subtropical cyclone formation (central Atlantic near 35N-55W)
IOH 48 Hr Outlook (1800Z Aug 31)...20% chance of tropical cyclone formation (northwestern Atlantic near 39N-57.5W)
IOH 72 Hr Outlook (1800Z Sep 1)...0% chance of tropical cyclone formation (just south of Newfoundland near 46N-56W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
0000Z (Aug 29) CMC Model Run...
**For area of interest #20...tropical cyclone formation suggested at 18.5N-57W at 96 hours... strengthens into a hurricane which reaches 24N-66W at 168 hours
**For area of interest #22...no development shown
**For area of interest #23...vigorous broad tropical wave emerges from the west coast of Africa at 24 hours... a tight circulation develops within the east side of the broad wave and just offshore of Senegal at 30 hours... tight circulation swings northwest around the remainder of the broad circulation and passes just north of the Republic of Cabo Verde Islands through 72 hours as a possible tropical cyclone... subsequently the tight circulation weakens and dissipates near 19N-31W at 114 hours... remainder of the broad wave's circulation continues west and reaches 20N-40W at 168 hours.
**For area of interest #24...small surface low currently located near 32N-55W dissipates over the next 36 hours.
**For area of interest #25...Stalled front located just northwest of area of interest #24 develops a new surface low supported by cut-off upper vortex near 36.2N-60.5W at 24 hours... possible tropical cyclone formation near 37N-58W at 42 hours... subsequently turns north in southerly flow out ahead of frontal system currently approaching from central North America and dissipates just east-southeast of Nova Scotia at 90 hours.
0000Z (Aug 29) ECMWF Model Run...
**For area of interest #20...tropical cyclone formation suggested near 23N-61W at 120 hours... reaches 26N-70W at 168 hours as a strong tropical storm
**For area of interest #22...no development shown
**For area of interest #23...vigorous broad tropical wave emerges from the west coast of Africa at 24 hours... organizes into a broad tropical low whose center passes just north of the Republic of Cabo Verde Islands at 72 hours... at 96 hours two smaller circulations develop in the broad low (one to the north near 22.5N-27W and one to the south near 16N-26.5W)...at 144 hours both circulations degnerate into a single broad wave axis near 25N-35.5W
**For area of interest #24...no development shown
**For area of interest #25...Stalled front located just northwest of area of interest #24 develops a new surface low supported by cut-off upper vortex near 37N-61.5W at 24 hours... drifts east to 35.5N-58.5W through 48 hours... subsequently turns north in southerly flow out ahead of frontal system currently approaching from central North America and dissipates offshore of Nova Scotia between 72 and 96 hours
**Tropical wave emerges from west coast of Africa at 120 hours... tropical cyclone formation suggested just east of the Republic of Cabo Verde Islands at 144 hours... begins to weaken while moving west-northwest across the islands through 168 hours.
1200Z (Aug 29) GFS Model Run...
**For area of interest #20...tropical cyclone formation suggested near 20N-57.5W at 93 hours... moves northwest while strengthening into an intense hurricane which reaches 29N-69.5W at 168 hours
**For area of interest #22...no development shown
**For area of interest #23...vigorous broad tropical wave emerges from the west coast of Africa at 12 hours... tight circulation develops within northeast part of the broad wave which strengthens into a tropical cyclone just northeast of the Republic of Cabo Verde Islands at 45 hours... after passing just north of the Republic of Cabo Verde Islands and proceeds to weaken to a remnant low near 18.8N-34W at 105 hours... remnant low weakens to a trough near 24N-33W at 168 hours.
**For area of interest #24...no development shown
**For area of interest #25...stalled front located just northwest of area of interest #24 develops a new surface low supported by cut-off upper vortex near 36.5N-61W at 12 hours... moves north and dissipates at 54 hours near 39N-57.5W
1200Z (Aug 29) NAVGEM Model Run...
**For area of interest #20...tropical cyclone formation suggested near 16.5N-57.5W at 66 hours... strengthens into a hurricane near 21.2N-63W by 120 hours... as a potentially intense hurricane located near 25.5N-70.5W at 168 hours
**For area of interest #22...no development shown
**For area of interest #23...tropical cyclone formation suggested just offshore of the Mauritania/Senegal border at 42 hours... passes just north of the Republic of Cabo Verde Islands at 84 hours... reaches 21.5N-34W at 120 hours...subsequently turns more north in track and reaches 27.8N-39W at 168 hours.
**For area of interest #24...no development shown
**For area of interest #25...no development shown
Commenti