*******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.**********
...THURSDAY AUGUST 25 2022 9:30 AM EDT...
The Atlantic tropics continue to make an attempt at waking up with three areas of interest lined up in from the Lesser Antilles to west coast of Africa as follows:
(1) A pair of vigorous tropical waves of low pressure are expected to merge into a tropical low pressure in the eastern tropical Atlantic in the next couple of days... see area of interest #20 section below for more information.
(2) See area of interest #21 section below for an update on the tropical low wave continuing to advance westward across the central tropical Atlantic.
(3) The southeast side of the tropical wave currently crossing the Lesser Antilles has left behind a tropical low pressure also now advancing into the islands. See area of interest #22 section below for an update on this feature.
Elsewhere...the surface trough of low pressure in the open western Atlantic (previously generated by the upper vortex now near the Bahamas) is currently moving north around the west side of the Atlantic surface ridge...with maximum vorticity of the trough located at its northeast end near 30N-70W according to the CIMSS 850 mb vorticity product (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). Despite passing below the low shear environment beneath an upper ridge axis in the region... there are currently no signs of development as the trough remains in an elongated instead of a circular state on the CIMSS product. Conditions going forward for the trough are expected to become increasingly hostile as it continues north into shearing mid-latitude upper westerlies to the north of the upper ridge axis... and tropical cyclone development here is not anticipated.
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 #22 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...A pair of closely spaced...large... and well-organized rotating tropical waves of low pressure continue sliding west across the eastern tropical/west coast of Africa region. Over the next couple of days the two waves are expected to merge into a large tropical low pressure area in the eastern tropical Atlantic. Favoring additional development of the tropical low pressure area will be the widespread tropical upper ridge with favorable low wind shear and upper outflow that has been dominating the region... which is expected to persist. Going against the tropical low pressure area is widespread dry Saharan air located just to the north. However given the pair of seedling tropical waves continue maintaining a large area of organizing thunderstorms... it appears this could be the system that finally breaks the suppressing spell of the dry Saharan air and I have therefore raised peak 5-day odds of tropical cyclone formation to 40% (note this is slightly higher than the NHC outlook's 20% as of this writing). However short-term odds of tropical cyclone formation are lowered as the two tropical waves have not yet shown signs of merging... and time will be needed for the waves to merge and the subsequent broad tropical low pressure area to consolidate. Regarding the forecast track for this area of interest... the net westward speed is initially slower as the two seedling waves merge into a sprawling area of low pressure. The westward speed around the south side of the steering Atlantic surface ridge is then increased to a typical 5W longitude per day rate.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0600Z Aug 26)...0% chance of tropical cyclone formation (south of the Republic of Cabo Verde Islands near 12.5N-24.5W)
IOH 48 Hr Outlook (0600Z Aug 27)...0% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-30W)
IOH 72 Hr Outlook (0600Z Aug 28)...15% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-35W)
IOH 96 Hr Outlook (0600Z Aug 29)...30% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-40W)
IOH 120 Hr Outlook (0600Z Aug 30)...40% chance of tropical cyclone formation (central tropical Atlantic near 13N-45W)
AREA OF INTEREST #21...The tropical wave of low pressure in the open central Atlantic has once again lost thunderstorm activity. Over the next 48 hours... changes in the upper atmosphere are expected to make conditions more hositle for development. Specifically the current north Atlantic upper ridge has cut-off a sizeable chunk of upper vorticity from the current northeast Atlantic upper trough. Expect this upper vorticity to retrograde southwest around the north Atlantic upper ridge and into the central tropical Atlantic where it will increase westerly wind shear and also suppress upper outflow needed for thunderstorm activity. Odds of tropical cyclone formation are dropped to 0%... and this is my 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 (0000Z Aug 26)...0% chance of tropical cyclone formation (central tropical Atlantic near 16N-47.5W)
AREA OF INTEREST #22...The southeast side of a tropical wave crossing the Lesser Antilles is leaving behind a tropical low pressure area also in the process of moving into the islands. After crossing the Lesser Antilles... the remainder northwest portion of the tropical wave and southwest side of the Atlantic surface ridge are expected to steer the tropical low pressure west-northwest into and across the Caribbean Sea over the next five days. The tropical low has potential to find shelter from wind shear while it slides underneath an axis of Caribbean upper ridging currently present... with the upper ridge axis also potentially allowing this system to establish a favorable upper outflow pattern. This feature has struggled to develop shower and thunderstorm activity... however in the last few short hours the northwest side of the tropical low has done a better job by developing a batch of banding thunderstorm features now moving across some of the southern Lesser Antilles. I dropped short-term odds of tropical cyclone formation and maintain a low 10% peak in the odds over the next five days until we see the thunderstorm activity persist... and also because the GFS model which previously developed this feature has now backed off on that solution. Note that odds of development are dropped back to 0% by day 5 as the latest model runs show some of the upper vortiicty currently near Bermuda retrograding southwest over this disturbance and suppressing upper outflow... this could explain the GFS model run backing off on showing development.
In approximately 4 to 5 days from now... the forecast track of this disturbance brings it near Jamaica and Haiti. Interests here should be aware that it could bring heavy rainfall with flash flooding potential in the day 4 timeframe (Sunday) regardless of tropical cyclone formation or not. By day 5 if the latest upper wind forecasts showing suppressed upper outflow verifies... the potential for rainfall will decrease.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0600Z Aug 26)...0% chance of tropical cyclone formation (just west of the Lesser Antilles near 12.6N-61.5W)
IOH 48 Hr Outlook (0600Z Aug 27)...0% chance of tropical cyclone formation (eastern Caribbean Sea near 14N-65.5W)
IOH 72 Hr Outlook (0600Z Aug 28)...10% chance of tropical cyclone formation (south of the Dominican Republic near 15.5N-70W)
IOH 96 Hr Outlook (0600Z Aug 29)...10% chance of tropical cyclone formation (south of Haiti near 17N-74W)
IOH 120 Hr Outlook (0600Z Aug 30)...0% chance of tropical cyclone formation (just northwes of Jamaica near 18.5N-78W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Aug 24) CMC Model Run...
**For area of interest #20...no development shown
**For area of interest #21...no development shown
**For area of interest #22...no development shown
**Vigorous tropical wave featuring broad low pressure spin emerges from the west coast of Africa at 138 hours... broad low pressure center located just northeast of the Republic of Cabo Verde Islands at 168 hours
1200Z (Aug 24) ECMWF Model Run...
**For area of interest #20...pair of tropical waves in eastern tropical Atlantic and west coast of Africa gradually merge into a large tropical low west-southwest of the Republic of Cabo Verde Islands at 48 hours... tropical low becomes a little stronger and better organized while reaching 13.5N-45.5W at 168 hours
**For area of interest #21...no development shown
**For area of interest #22...no development shown
**Vigorous tropical wave featuring well-defined low pressure center emerges from the west coast of Africa at 144 hours... tropical cyclone formation suggested while organized wave moves into the Republic of Cabo Verde Islands at 168 hours
1800Z (Aug 24) GFS Model Run...
**For area of interest #20...no development shown
**For area of interest #21...no development shown
**For area of interest #22...no development shown
**Vigorous tropical wave featuring well-defined low pressure center emerges from the west coast of Africa at 120 hours... tropical cyclone formation just offshore of Africa near 13.5N-19W at 129 hours... rapidly strengthens into a strong tropical storm or hurricane while moving into the Republic of Cabo Verde Islands at 156 hours... located just west of the Republic of Cabo Verde Islands as a potential hurricane at 168 hours.
1800Z (Aug 24) NAVGEM Model Run...
**For area of interest #20...no development shown
**For area of interest #21...no development shown
**For area of interest #22...no development shown
**Vigorous tropical wave featuring broad low pressure spin emerges from the west coast of Africa at 150 hours