*******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.**********
...WEDNESDAY AUGUST 31 2022 11:59 PM EDT...
For the first time since 1997... the month of August has concluded with zero Atlantic tropical cyclones for the month. However September has the potential to start active due to the following areas of interest in the tropical latitudes:
(1) See area of interest #20 section below for more information on an organizing tropical low pressure in the central tropical Atlantic. Note that this system will pass near the northern Lesser Antilles on Friday.
(2) See area of interest #22 section below for an update on the disturbance in the western Caribbean Sea.
(3) The tropical low pressure in the far eastern Atlantic is currently situated between the Republic of Cabo Verde Islands and Mauritania. See area of interest #23 section below for more information.
(4) Various model runs in recent days depict organized tropical waves of low pressure emerging from western Africa in the wake of area of interest #23 for the days ahead. Additional areas of interest in this region may need declaring in future updates.
In addition... the mid-latitudes of the Atlantic may host tropical development in the days ahead as follows:
(1) See area of interest #25 and #26 sections below for more information on possible open central Atlantic tropical development over the next few days.
(2) A frontal cyclone over eastern Canada has driven a cold front into the western Atlantic waters offshore of the United States east coast. So far there are no signs of tropical development along the tail end of this front.
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 #26 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...Over the last 48 hours... the broad tropical low pressure system in the open central Atlantic has continued to lack westward progress. The CIMSS 850 mb vorticity product (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) showed the circulation was quiet elongated southwest-to-northeast. The slow westward progress could therefore be diagnosed to the elongated circulation consolidating into a more circular one. The more recent circular structure of the circulation is confirmed by the very latest CIMSS 850 mb vorticity analysis. Meanwhile the associated thunderstorm activity continues to make attempts at organizing... with activity limited in the northwest quadrant of the circulation to due light westerly shear caused by upper vorticity located nearby to the northwest.
Given the more organized circular (instead of elongated) circulation... and that computer models all agree on eventually developing this system into a tropical cyclone... I have begun a tropical cyclone formation forecast with specific track and intensity points as outlined below. The updated forecast track is adjusted as needed to comprehend the lack of westward progress in the last 48 hours... and shows a gradually increasing northward bend in the westward track as this system first rounds the southwestern side of the Atlantic surface ridge. The current eastern Canada frontal system is currently heading into the western Atlantic... however by day 3 it will be departing 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 at 3+ days as this system is likely to be tall/strong enough to be steered by the upper vorticity to the northwest. A complete turn to the north is anticipated by day 5 as an additional upper trough... associated with an additional frontal system to pivot into the western Atlantic from North America... teams up with the lingering upper vorticity.
Regarding the intensity forecast... development and intensification is shown to be initially gradual due to the aforementioned shear caused by the upper vorticity. The models then agree that the upper vorticity will weaken while remaining cut-off from high-latitude cold air... resulting in this system moving into a break in the upper vorticity where wind shear will be lower and upper outflow will be higher. This explains the more brisk strengthening rate into a hurricane at days 3 and 4 in the forecast below. However as stated above and by day 5... the upper vorticity in the region will likely be re-invigorated with the approach of an upper trough. Therefore the 5-day intensity forecast ends by showing some weakening.
Regarding impact to land areas... this system on its current forecast track will pass just northeast of the Lesser Antilles on Friday. During this time the southwestern quadrant of the circulation has potential to bring heavy rains... gusty winds... and coastal sea swells. Should this system as a hurricane gain enough strength and size... coastal sea swells could spread to the Virgin Islands... Puerto Rico... Bahamas... and Bermuda this weekend and into early next week.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Aug 31)...Tropical low centered in the central tropical Atlantic at 16N-52W
IOH 24 Hr Forecast (1800Z Sep 1)...Tropical low centered in the central tropical Atlantic at 17.5N-56W
IOH 48 Hr Forecast (1800Z Sep 2)...40 mph maximum sustained wind tropical storm centered just northeast of the northern Lesser Antilles at 18.5N-60W
IOH 72 Hr Forecast (1800Z Sep 3)...60 mph maximum sustained wind tropical storm centered in the western Atlantic at 20.5N-63W
IOH 96 Hr Forecast (1800Z Sep 4)...90 mph maximum sustained wind hurricane centered in the western Atlantic at 22.5N-66W
IOH 120 Hr Forecast (1800Z Sep 5)...75 mph maximum sustained wind hurricane centered in the western Atlantic at 26N-66W
AREA OF INTEREST #22...The surface trough/tropical wave that was traversing westward across the Caribbean Sea has finished crossing Central America and now straddles the Bay of Campeche and eastern Pacific at 93W longitude. However the thunderstorm activity in the western Caribbean did not follow this feature... with rounds of activity continuing to be supported by split flow upper divergence between the west side of upper vorticity hanging around the northern Caribbean islands and southeast side of an upper ridge lingering over the western Gulf of Mexico and Texas. Meanwhile it was previously thought that upper vorticity to be deposited in the Gulf of Mexico by the current eastern Canada upper trough would be disruptive to development potential. However the amount of Gulf upper vorticity actually left behind is less and also located further east than previously forecasted in the models. This will give an opportunity for the Gulf upper vorticity to merge with the northern Caribbean islands upper vorticity and thus continue the above-mentioned split flow upper divergence regime. Regarding surface vorticity... this disturbance has taken advantage of spin from an additional tropical wave passing through the western Caribbean and previously associated with area of interest #21 from a few days ago. The CIMSS 850 mb vorticity product http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) shows the maximum spin of the disturbance is along this tropical wave and north coast of Honduras... southwest of the previous forecast track and therefore the updated one in the outlook below is adjusted accordingly. The new forecast track takes this system west-northwest into the Bay of Campeche from Belize/southeastern Mexico while rounding the southwest side of the steering Atlantic surface ridge. A more westward track into Veracruz is shown by the end of the forecast as steering surface ridging over North America increases after the departure of the current eastern Canada frontal system and additional frontal system to follow behind but also quickly pivoting across North America. I forecast possible tropical cyclone formation as this system moves across the Bay of Campeche as it potentially takes advantage of the ongoing split flow upper divergence... however I set low 10% odds as computer model support showing this is absent.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Sep 1)...0% chance of tropical cyclone formation (east coast of Belize near 17N-88W)
IOH 48 Hr Outlook (1800Z Sep 2)...0% chance of tropical cyclone formation (eastern Bay of Campeche coast of Mexico near 18.8N-91W)
IOH 72 Hr Outlook (1800Z Sep 3)...10% chance of tropical cyclone formation (central Bay of Campeche near 19.8N-94W)
IOH 96 Hr Outlook (1800Z Sep 4)...0% chance of tropical cyclone formation (central Veracruz near 20.2N-98W)
AREA OF INTEREST #23...The tropical low pressure spin located just offshore of the African west coast over the last 48 hours has drifted northward to the waters offshore of Mauritania instead of proceeding westward and further offshore. As covered in previous updates... this system emerged from the merger of two closely-spaced tropical waves that were over western Africa... and perhaps the merged circulation had an initial southwest-northeast elongation. Moreover the observed northward movement could be the result of the northeast side of the elongated circulation becoming the dominant... with the dominant circulation swinging northward around the remainder dissipating southwestern part of initial circulation. This evolution is something that model runs in the past days suggested... and with this actually coming to fruition my updated forecast track below is adjusted accordingly. The forecast track shows an initial westward acceleration around the south side of the Atlantic surface ridge. By day 5 an increasing turn towards the north is anticipated as the ridge develops a weakness induced by area of interest #26. Regarding probabilities of tropical cyclone formation... the initial northward swing in track this system has taken has exposed it to less favorable thermodynamic conditions... specifically a combo of dry Saharan air and marginally warm 26 deg C waters only just enough for tropical development. Therefore I have greatly cut odds of tropical cyclone formation to 30% from the 60% shown in the previous update. As this system turns increasingly northwest into upper westerly shearing flow on the north side of tropical upper ridging in the region and south side of upper vorticity associated with area of interest #26... conditions will become even more hostile for tropical development. Therefore odds of development are trimmed down to 0% by day 5.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Sep 1)...30% chance of tropical cyclone formation (just northwest of the Republic of Cabo Verde Islands near 18.5N-25W)
IOH 48 Hr Outlook (1800Z Sep 2)...30% chance of tropical cyclone formation (eastern tropical Atlantic near 19N-30W)
IOH 72 Hr Outlook (1800Z Sep 3)...20% chance of tropical cyclone formation (eastern tropical Atlantic near 19.5N-35W)
IOH 96 Hr Outlook (1800Z Sep 4)...10% chance of tropical cyclone formation (central tropical Atlantic near 20N-40W)
IOH 120 Hr Outlook (1800Z Sep 5)...0% chance of tropical cyclone formation (central Atlantic near 22.5N-41W)
AREA OF INTEREST #25... The northwestern Atlantic surface low pressure... spawned 48 hours ago by parent upper vorticity left behind the current north Atlantic upper vortex... has begun accelerating north in the flow ahead of the surface frontal cyclone approaching from eastern Canada. The current area of rotating showers and thunderstorms just north of Bermuda should not be confused with the surface low... instead this area is associated with the parent upper vorticity which has recently coalesced into an upper vortex. Instead the surface low is a faint and compact cloud swirl seen further north. Tropical cyclone formation is no longer possible as the surface low will soon reach cool waters on its northward trajectory... 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 (1800Z Sep 1)...0% chance of tropical cyclone formation (just offshore of east tip of Nova Scotia near 46N-59.5W)
AREA OF INTEREST #26...Through Tuesday afternoon and Wednesday... global models remarkably and abruptly came into agreement on bullish subtropical cyclone formation in the north-central Atlantic and to the east of area of interest #25. This appears related to the models struggling in their handling of how exactly the eastern Canadian frontal system would evolve. For example as noted in the above area of interest #22 section the frontal system has actually left behind less upper vorticity in the Gulf of Mexico than previously anticipated. The amount of warm air and associated north Atlantic upper ridging ahead of the frontal system is also higher than previously projected. The stronger north Atlantic upper ridge was just enough for the models to now project that an additional string of upper vorticity would be cut-off from the current adjacent north Atlantic upper vortex... with the cut-off string gradually evolving into an upper vortex whose divergence zone would kick off a surface low that acquires tropical characteristics. Some solutions are bullish enough to suggest the subtropical cyclone would establish enough thunderstorm latent heat release to develop a warm core outflow layer below the upper vortex... enough to make the transition to fully tropical and strengthen into a hurricane. This marks yet another attempt at tropical development in the mid-latitudes of the Atlantic in recent days.
Given the above model solutions and surface low already becoming established with organized thunderstorm activity on Wednesday afternoon... this new area of interest has already been given high 80% odds of subtropical or tropical cyclone formation by the National Hurricane Center. However I start with notably lower 50% odds of tropical cyclone formation as the thunderstorm activity has since waned... a reflection of potentially not so favorable thermodynamic conditions given the position of this system over marginally warm water. In addition the cut-off upper vortex is not forecast to be particularly cold enough to help kick off instability (to measure 1224 dekameters in height at 200 mb instead of 1200 or less). My odds are increased to 60% when the models agree that the upper vortex and its associated focused supportive eastern divergence zone becomes established. The forecast track is initially a slow meander to the east aligned with the position/motion of the upper vortex. By day 5 a faster northeast track is expected once the current east Canada upper trough approaches and absorbs the upper vortex. This would drive this system into cooler waters... with the east side of the upper trough potentially increasing the overhead southwesterly wind shear. As a result I trim development odds back to 50% at the end of the 5-day forecast period.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Sep 1)...50% chance of subtropical cyclone formation (north Atlantic near 37.5N-46W)
IOH 48 Hr Outlook (1800Z Sep 2)...60% chance of subtropical cyclone formation (north Atlantic near 37.5N-46W)
IOH 72 Hr Outlook (1800Z Sep 3)...60% chance of subtropical cyclone formation (north Atlantic near 37.5N-44W)
IOH 96 Hr Outlook (1800Z Sep 4)...60% chance of subtropical cyclone formation (north Atlantic near 37.5N-44W)
IOH 120 Hr Outlook (1800Z Sep 5)...50% chance of subtropical cyclone formation (north Atlantic near 39N-40W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
0000Z (Aug 31) CMC Model Run...
**For area of interest #20...tropical cyclone formation suggested at 22.5N-64.5W at 102 hours... drifts north to 27N-66W at 168 hours as a potentially intense hurricane.
**For area of interest #22...no development shown
**For area of interest #23...tropical low passes just north of the Republic of Cabo Verde Islands at 30 hours... weakens to a tropical wave near 20N-40W at 138 hours
**For area of interest #25...while continuing north surface low dissipates near 40N-57.5W at 18 hours
**For area of interest #26...surface low forms near 38N-47.5W at 18 hours... subtropical cyclone formation suggested near 37.2N-43W at 72 hours... located at 38.8N-44W at 120 hours
0000Z (Aug 31) ECMWF Model Run...
**For area of interest #20... tropical cyclone formation suggested at 22N-63W at 96 hours... while remaining a weak tropical cyclone reaches waters northeast of the eastern Bahamas at 168 hours
**For area of interest #22...no development shown
**For area of interest #23... tropical low passes just north of the Republic of Cabo Verde Islands just after 24 hours... weakens to a tropical wave near 20N-40W at 120 hours
**For area of interest #25... while continuing north surface low dissipates in next 24 hours
**For area of interest #26... subtropical cyclone formation suggested near 39.2N-44W at 48 hours... while meandering acquires fully tropical status and hurricane strength through 120 hours while located near 39N-43W
**Tropical wave emerges from west coast of Africa at 72 hours... organizes into a tropical low east of the Republic of Cabo Verde Islands at 96 hours... tropical cyclone formation suggested near 22.5N-38W at 168 hours
**Tropical wave emerges from west coast of Africa at 144 hours... organizes into a tropical low south of the Republic of Cabo Verde Islands at 168 hours
0600Z (Aug 31) GFS Model Run...
**For area of interest #20... tropical cyclone formation suggested near 22.2N-62W at 84 hours... curves northeast in track and reaches 29N-58W at 168 hours as a potentially intense hurricane
**For area of interest #22...no development shown
**For area of interest #23...passes just north of the Republic of Cabo Verde Islands as a possible tropical depression at 24 hours... weakens to a remnant low near 18.8N-31W at 63 hours... weakens to a tropical wave near 25N-42W at 135 hours
**For area of interest #25... while continuing north surface low dissipates near 40N-58W at 12 hours
**For area of interest #26... subtropical cyclone formation suggested near 38.5N-45W at 48 hours... while meandering acquires fully tropical status and hurricane strength through 120 hours while located near 39N-43W
0600Z (Aug 31) NAVGEM Model Run...
**For area of interest #20... tropical cyclone formation suggested near 20.5N-59.8W at 84 hours... curves north in track and reaches 25.5N-63.5W at 168 hours as a potentially intense hurricane
**For area of interest #22...no development shown
**For area of interest #23... tropical low passes just north of the Republic of Cabo Verde Islands at 36 hours... weakens to a tropical wave near 25N-36W at 102 hours
**For area of interest #25... while continuing north surface low dissipates within next 6 hours
**For area of interest #26... surface low drifts east-southeast and reaches 37.5N-42.5W at 120 hours