*******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 SEPTEMBER 20 2022 2:28 AM EDT...
Fiona pulling northward away from the Dominican Republic and toward the easternmost Bahamas while strengthening further into a major hurricane... interests in the easternmost Bahamas should have completed preparations for Fiona by now. See Fiona section below for more information the hurricane. Also monitoring three other areas of interest in the Atlantic tropics as follows:
(1) See area of interest #29 section below for an update on the tropical disturbance in the open central Atlantic.
(2) See area of interest #30 section below for information on a tropical wave making a comeback as it moves toward northeastern Venezuela... Trinidad and Tobago... and the southern Lesser Antilles. There is an increasing risk this wave develops into a tropical cyclone that moves across the Caribbean Sea in the long range.
(3) See area of interest #32 section below for a tropical wave of low pressure that may develop midway between the west coast of Africa and Republic of Cabo Verde Islands in a few days from now.
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 #29... #30... and #32 as the other numbers were used in previous birdseye view posts. 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.
MAJOR HURRICANE FIONA... The second hurricane of the 2022 Atlantic season has spent much of Monday morning and afternoon grazing its eye west-northwest across the eastern tip and north-facing coast of the eastern Dominican Republic. After peaking to 90 mph maximum sustained winds just before moving onto the eastern tip of the Dominican Republic... Fiona's intensity faded to a minimum 80 mph maximum sustained winds during the land interaction. More recently the remainder of the upper vorticity west of the hurricane has finally lifted the track of the hurricane on a more north angle... allowing the eye to peel away from the north coast of the Dominican Republic and in the general direction of the easternmost islands of the Bahamas. Because Fiona's tight core and small eye has remained intact despite the land interaction... this also means that Fiona has also been able to intensify quickly into a category 2 with 105 mph maximum sustained winds. Additional rapid intensification is possible before the hurricane's eye moves over or just near the easternmost Bahamas on Tuesday... preparations for possible life-threatening wind and coastal storm surge should have been completed by now in this area... more on the intensity forecast of Fiona in the next paragraph. Regarding the forecast track... what remains of the dissipating upper vorticity to the west of Fiona should bend the track more north in the next 24 hours. After 24 hours... steering upper southwesterly flow is expected to increase in Fiona's environment and kick the hurricane on a north and then northeast recurvature. The initial increase in the upper southwesterly flow will be brought on when the current southeast US cut-off upper trough gets pushed offshore and toward Fiona by the current northern upper trough streaming eastward across the Great Lakes region of North America... and also by a second northern upper trough to approach from central and eastern Canada. The latest model data regarding the shape of the pair of northern upper troughs now indicates the southeastern US cut-off upper trough will not get dragged toward Fiona as quickly as previously thought... resulting in a delay in the eastward angling of Fiona's track and thus an overall west shift in the long range model guidance. The westward shift in Fiona's long range track is also exacerbated by the more amplified presentation of the second of the northern upper troughs which will have more southerly and less westerly steering flow as it nears Fiona. This will allow Fiona to move more north and less east... right into the eastern divergence maximum of the second upper trough. The sprawling divergence maximum in turn will allow Fiona to grow into a large and powerful non-tropical remnant frontal cyclone once over cooler water... and the west side of the remnant cyclone will pull cold air associated with the trough southward and cause it to amplify further into an upper vortex. In turn this would mean the remnant cyclone swings northwest in track... right into Atlantic Canada... while whirling into the center of the forming upper vortex. The west shift in the long-range model guidance now means Fiona's powerful remnant cyclone could bring substantial wind... rain... and coastal surge impacts to a large part of Atlantic Canada instead of just Newfoundland by day 5.
Regarding forecast intensity... Fiona's currently tight core... small eye... and its improving western outflow... as the upper vorticity west of Fiona continues to weaken... could very well allow Fiona to intensify into a major category 4 hurricane in the next 24 hours... and this is what I forecast below. The exact peak intensity I selected is similar to what the NHC shows in their intensity forecast as of this writing. The increase in all intensity forecasts is reasonable as Fiona's current intensity is already ahead of all previous forecasts from yesterday. I project gradual weakening from 24 to 72 hours as upper southwesterly flow is expected to increase in Fiona's environment as noted in the prior paragraph. The upper southwesterly flow would block the western outflow of the hurricane or even shear it some... however the shear may be mitigated by the storm's forecast northeast acceleration aligned with the upper wind direction which explains the graduated instead of rapid weakening rate in the forecast. Also noted in the prior paragraph... Fiona in the long range now looks to be more aligned with the divergence maximum of a major upper trough to approach from Canada... therefore I show a slower weakening rate than before in what is now the 72 to 96 hour timeframe.
Regarding impact to land areas:
(1) For the Dominican Republic... coastal surf... heavy rainfall... and gusty winds will continue to subside over the next several hours as Fiona pulls northward and away. The hurricane has also moved far west enough and has gained enough strength to bring coastal surf to the north coast of Haiti... however surf here will also be decreasing with time.
(2) For the eastern Bahamas... preparations for tropical storm conditions (winds and coastal surf) should be finished by Monday evening. The Turks and Caicos islands remain under a hurricane warning as the eye of a potentially intense Fiona could pass over or nearby within the next 24 hours... this could be a life-threatening situation due to extreme wind and coastal storm surge and preparations here should have also been completed by now!
(5) Coastal surf is also expected on the shores of the central and western Bahamas. The west shift in the long range track will also be enough to bring more pronounced coastal swells and rip currents to the United States mid-Atlantic and northeast coastline.
(6) The current west shift in the long range track could mean tropical storm instead of hurricane force conditions for Bermuda on Thursday or Friday. However the forecast track can still shift again as computer model data continues to get updated... therefore interests here should remain on guard for potential hurricane-force conditions as well. Preparations here may need to begin Tuesday (later today) or Wednesday.
(7) I recommend interests in the Candian provinces of Nova Scotia... Prince Edward Island... Newfoundland... eastern Quebec... and eastern Labrador remain aware of Fiona as it has potential to move into the region as a hurricane-force remnant frontal cyclone this upcoming weekend. The western portions of Labrador may also see impacts from this system if the westward shift in the long-range model guidance holds.
Update as of 2 AM EDT... Fiona has strengthened into the first major category 3 hurricane of this Atlantic season while obtaining 115 mph maximum sustained winds.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 20)...110 mph maximum sustained wind hurricane centered just offshore of the Dominican Republic north coast and just southeast of the eastern Bahamas at 20.6N-70.3W
IOH 24 Hr Forecast (0000Z Sep 21)...135 mph maximum sustained wind major hurricane centered just north of the easternmost Bahamas at 22.5N-71.2W
IOH 48 Hr Forecast (0000Z Sep 22)...125 mph maximum sustained wind major hurricane centered at 25.5N-70.5W
IOH 72 Hr Forecast (0000Z Sep 23)...115 mph maximum sustained wind major hurricane centered west-southwest of Bermuda at 30N-67.5W
IOH 96 Hr Forecast (0000Z Sep 24)...100 mph maximum sustained wind hurricane centered at 39N-57.5W
IOH 120 Hr Forecast (0000Z Sep 25)...Hurricane-force remnant frontal cyclone centered on the south coast of eastern Quebec at 50N-60.5W
AREA OF INTEREST #29...The surface low pressure in the open central Atlantic that has been enhanced by the eastern divergence zone of an upper vortex in the region has lifted northward while steered by the west side of the Atlantic surface ridge. Light southerly shear induced by the east side of the upper vortex previously displaced all the shower and thunderstorm activity to the north side of the surface low. Over the last 24 hours the surface low has since become better organized while developing a well-defined swirl... with the showers and thunderstorms to the north making attempts at wrapping into the circulation center from the west... a sign of lower shear as the surface low has moved away from the upper vortex. The current amplified northwest Atlantic upper trough is currently sending a smaller and low-amplitude shortwave trough eastward toward this surface low. Given the surface low has become markedly better organized... an abrupt increase in thunderstorms is all that is needed to strengthen the surface low into a tropical depression... and the eastern divergence zone of the approaching shortwave upper trough may provide the kick needed for such thunderstorms. Thus it makes sense the NHC has increased tropical cyclone formation odds... and I have set my odds for the next 24 hours higher than the NHC as of this writing... up at 70% as thunderstorms are already increasing in a flare just northwest of the center. After 24 hours... a surface ridge is expected to build to the north of this disturbance... underneath the western convergence zone of the current northwest Atlantic upper trough as that trough pivots into the northeast corner of the Atlantic. However an east bend in the northward track... shown in some of the model runs... is possible if indeed this system becomes a tropical cyclone strong/tall enough to couple to the mid-latitude upper westerly flow. My forecast track between 24 and 48 hours is weighted toward the west... giving more influence to the building surface ridge to the north and less influence to the upper westerly winds... as I suspect this system will quickly weaken to a shallow feature during that timeframe while moving into waters below 26 deg C and as westerly shear increases once the approaching shortwave upper troughs cuts across the top of this system. I also drop development odds to 0% by 48 hours.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 21)...70% chance of tropical cyclone formation (central Atlantic near 33N-45.5W)
IOH 48 Hr Outlook (0000Z Sep 22)...0% chance of tropical cyclone formation (central Atlantic near 37.5N-44W)
AREA OF INTEREST #30...The central Atlantic tropical wave of low pressure that was tagged as area of interest #30 on this blog... in birdseye view post #104... has made a comeback while generating renewed showers and thunderstorms in the vicinity of 10N-50W. Previously it was anticipated that Hurricane Fiona's upper outflow would push the upper vortex associated with area of interest #29 southward into this tropical wave... thus suppressing upper outflow needed for tropical development. Instead Fiona has moved further west than previously anticipated... thus its upper outflow has not pushed the upper vortex as far south as previously thought... allowing the tropical wave's comeback in a supporting upper outflow environment just south of the upper vortex. In the last 24 hours... the models have latched onto these trends and now develop the tropical wave as it later moves across the Caribbean Sea... where the regional tropical upper ridge axis with low shear and upper outflow is expected to persist. The GFS is most aggressive and suggesting tropical cyclone formation in the short-term as this system moves toward and then across the southern Lesser Antilles. The GFS is picking up on a potential short-term boost the tropical wave may receive in an area of split flow upper divergence to setup between the southwest side of the aforementioned upper vortex and south side of the aforementioned tropical upper ridge axis.
I have set short-term odds of tropical cyclone formation to 0% as the tropical wave does not currently have a consolidated center of circulation needed to take off immediately. However in acknowledgement of the GFS solution... I begin to raise odds of development already just above the 10% mark by 48 hours and increase them to 40% by day 5. This is in agreement with the NHC outlook as of this writing. The already higher odds seem sensible as multiple global model runs are in agreement on developing this wave... and the tropical upper ridge axis that lies ahead in the Caribbean will make upper-level winds supportive for development. Regarding the forecast track... the westward track is expected to bend more north over the next 96 hours toward the surface ridge weakness being induced by Hurricane Fiona. As the weakness closes by 120 hours with Fiona pulling northward and away... the forecast track bends back more westward.
If current trends continue... interests in northeastern Venezuela... Trinidad and Tobago... and the southern Lesser Antilles are likely to see gusty winds and heavy rains from this tropical wave on Wednesday regardless of tropical cyclone formation or not.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 21)...0% chance of tropical cyclone formation (east of Trinidad near 10N-55W)
IOH 48 Hr Outlook (0000Z Sep 22)...15% chance of tropical cyclone formation (just northeast of Tobago near 11.2N-60W)
IOH 72 Hr Outlook (0000Z Sep 23)...25% chance of tropical cyclone formation (eastern Caribbean Sea near 12.5N-64W)
IOH 96 Hr Outlook (0000Z Sep 24)...35% chance of tropical cyclone formation (central Caribbean Sea near 14.5N-67W)
IOH 120 Hr Outlook (0000Z Sep 25)...40% chance of tropical cyclone formation (central Caribbean Sea near 15.5N-71W)
AREA OF INTEREST #32... Satellite image highlighting an organized tropical wave of low pressure moving across western Africa. Satellite image taken at 0300Z:
A vigorous tropical wave of low pressure over western Africa has become better defined while establishing a more consolidated gyre of thunderstorm activity centered in the vicinity of 12N-1W. Computer models insist that the tropical wave has potential to develop at an unusually north location offshore of Africa... between Mauritania and the Republic of Cabo Verde Islands... in approximately 96+ hours. While water temps in this area are currently above the 26 deg C threshold needed for tropical cyclone formation... tropical cyclone development is usually precluded in this region by dry Saharan air. However given the insistence shown in the global models... I have continued this tropical wave of low pressure as an area of interest on this blog. Due to the currently improved organization of the wave and insistence of the models... I have slightly raised my peak odds of tropical cyclone formation to 15%. The slight raise and still-low odds are a reflection of the climatology that does not usually favor development here.
The eastern divergence zone of the current eastern Atlantic upper trough is expected to keep low surface pressures across northwestern Africa and the Iberian Peninsula of Europe... and the models insist the tropical wave will have a north angle in track across Africa caused by this low pressure field such that it later emerges offshore at a more north location. Even though the Atlantic surface ridge is expected to remain intact in the long range... the models see that this system could quickly develop into a strong/tall enough circulation to continue angling north in track due to upper southwesterly flow on the north side of the tropical upper ridge in the region... and out ahead of a fragment of upper troughing to be left behind by the current eastern Atlantic upper trough. The upper southwesterly flow will produce some shear... however not too high to shunt tropical development... especially as the fragment of the cool core upper troughing is forecast to dissipate by day 5 while remaining cut-off from high-latitude cold air.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 21)...0% chance of tropical cyclone formation (western Africa near 13N-6W)
IOH 48 Hr Outlook (0000Z Sep 22)...0% chance of tropical cyclone formation (western Africa near 14N-11W)
IOH 72 Hr Outlook (0000Z Sep 23)...0% chance of tropical cyclone formation (west coast of Africa near 15N-16W)
IOH 96 Hr Outlook (0000Z Sep 24)...10% chance of tropical cyclone formation (east of the Republic of Cabo Verde Islands at 16N-21W)
IOH 120 Hr Outlook (0000Z Sep 25)...15% chance of tropical cyclone formation (just north of the Republic of Cabo Verde Islands at 18N-24W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Sep 19) CMC Model Run...
**For Hurricane Fiona... weakens to a strong tropical storm while moving northwest into the eastern Bahamas over next 24 hours... after lifting north away from the Bahamas re-strengthens into a larger hurricane while reaching 27N-72.5W at 66 hours... turns northeast and passes just northwest of Bermuda at 102 hours... swings more north in track and nears eastern Nova Scotia at 120 hours while transitioning into a large remnant frontal cyclone
**For area of interest #29... surface low curves north and northeast in track and weakens to a trough near 40N-39W at 84 hours
**For area of interest #30... tropical wave develops a tropical low near the ABC Islands (Aruba Bonaire and Curacao) at 90 hours... tropical low moves west-northwest across the Caribbean and passes just north of the eastern Honduras coast by 168 hours.
**Tropical low currently south-southwest of the Republic of Cabo Verde Islands drifts only slowly west while tugged by larger and stronger tropical wave approaching from western Africa (area of interest #32)... on its westward drift it reaches 11N-30W at 72 hours... tropical cyclone formation suggested by 120 hours as tropical low drifts further west to 11N-34W
**For area of interest #32... large and strong tropical wave currently over western Africa emerges from west coast of Africa at 66 hours... organizes into a tropical low midway between Senegal and Republic of Cabo Verde Islands through 96 hours... moves west-northwest and passes just north of the Republic of Cabo Verde Islands through 150 hours while almost becoming a tropical depression... tropical low located at 20N-35.5W at 168 hours.
1200Z (Sep 19) ECMWF Model Run...
**For Hurricane Fiona... center passes just east of the Turks and Caicos Islands over next 24 hours... passes west of Bermuda at 96 hours... swings more north in track and nears eastern Nova Scotia at 120 hours while transitioning into a large remnant frontal cyclone.
**For area of interest #29... surface low turns north then northeast in track and dissipates west-southwest of the Azores by 120 hours.
**For area of interest #30...tropical cyclone formation suggested in the central Caribbean Sea near 15N-77W at 144 hours... rapidly strengthens into a strong tropical storm located near 17N-81.2W at 168 hours.
**For area of interest #32... tropical wave emerges from west coast of Africa at 72 hours... tropical cyclone formation suggested just northeast of the Republic of Cabo Verde Islands at 96 hours... turns northwest and becomes a strong tropical storm near 20.2N-22.5W at 120 hours
1800Z (Sep 19) GFS Model Run...
**For Hurricane Fiona... center passes just east of the Turks and Caicos Islands over next 18 hours... center passes just northwest of Bermuda at 87 hours... transitions into a large non-tropical frontal cyclone whose center moves into the southwest corner of Newfoundland at 114 hours... circulation center whirls northwest into the Gulf of St. Lawrence through 120 hours.
**For area of interest #29... surface low moves north-northeast and becomes a tropical cyclone near 35.5N-43W at 45 hours... subsequently weakens to a remnant trough near 40.5N-37.5W at 90 hours... through 120 hours the northward moving remnant trough gradually loses definition on the outer east side of ex-Fiona's rather large circulation.
**For area of interest #30...tropical cyclone formation suggested east of Trinidad near 10.5N-57W at 48 hours... moves west-northwest across the southern Lesser Antilles through 69 hours as a compact tropical storm... does not gain additional strength while moving west-northwest into the open eastern Caribbean and reaching 15N-66W at 99 hours... bends more west in track and reaches 15.5N-69.5W at 120 hours
**For area of interest #32... tropical wave emerges from west coast of Africa at 69 hours... organizes into a broad tropical low midway between the west coast of Africa and Republic of Cabo Verde Islands through 87 hours... tropical low turns north in track and reaches 20N-20W at 120 hours
1200Z (Sep 19) NAVGEM Model Run...
**For Hurricane Fiona... center passes over the Turks and Caicos Islands at 30 hours... center passes just northwest of Bermuda at 108 hours... curves swings more north in track and reaches 40.5N-60.5W at 120 hours while transitioning into a large and strong non-tropical frontal cyclone
**For area of interest #29... surface low moves north-northeast and weakens to a trough near 34.5N-45.2W at 54 hours.
**For area of interest #30... tropical wave crosses southern Lesser Antilles at 66 hours while evolving into a tropical low... while curving northwest and north toward ridge weakness created by Fiona the tropical low moves into the Virgin Islands and east coast of Puerto Rico by 120 hours.
**For area of interest #32... no development shown