*******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.**********
...SUNDAY NOVEMBER 6 2022 5:22 AM EDT...
The Atlantic tropics remain exceptionally and unusually active for November due to multiple areas of interest as follows:
(1) See Lisa section below for a final statement on the dissipating former tropical cyclone.
(2) See area of interest #44 section below for more information on the subtropical cyclone forecast to form in the western Atlantic and swing west toward the northwestern Bahamas and Florida peninsula later this week.
(3) See area of interest #45 section below for an update on the frontal low pressure area well east of Bermuda showing signs of tropical characteristics.
(4) An additional frontal low pressure area well southwest of the Azores... located near 32.5N-36W as of this writing... is also producing shower and thunderstorm activity. This activity however has recently become sheared eastward from its surface circulation as a fragment of the current upper trough associated with ex-Martin is becoming pushed toward it by the deep-layer ridge currently in the western Atlantic. In addition after this upper trough fragment passes southeastward over this system... upper convergence on its northwest side will weaken it. Therefore this frontal low pressure area is not expected to develop as a tropical system.
(5) A tropical wave of low pressure in the open central Atlantic has potential to develop over the next five days while heading toward the southern Lesser Antilles... Trinidad and Tobago... northeastern Venezuela... and the southeastern Caribbean Sea. See area of interest #47 section below for more information.
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 is designated #44... #45... and #47 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.
REMNANTS OF LISA... The circulation of Lisa has continued to meander aimlessly in the western Bay of Campeche as the surface cold front over the central US has passed too far north to steer it... and only a weak surface ridge built to the north of Lisa over Texas/NE Mexico under the western convergence zone of the front's upper trough. This ridge is too weak to effectively move Lisa... furthermore as the upper trough is already pivoting eastward the weak surface ridge is following suit and has already quickly shifted east and away from Lisa while currently located over Louisiana... and will soon merge with the surface layer of the deep-layer ridge located well northeast of Lisa. Upper-level westerly winds on the south side of the front's upper trough have meanwhile sheared off and stripped away Lisa's thunderstorms from its nearly-stationary surface circulation... and whatever remains of the circulation has given up while no longer producing thunderstorms. The weakening circulation has therefore been downgraded to from a tropical depression to a remnant surface low pressure and is expected to soon dissipate. This is my final statement on Lisa on this blog as it is no longer a tropical cyclone.
AREA OF INTEREST #44... Over the last 24 hours... the upper trough located near the eastern Bahamas is evolving into an upper vortex cut-off from the mid-latitude westerlies thanks to an unseasonably warm deep-layer ridge emerging into the western Atlantic from eastern North America. The eastern divergence zone of the vortex has caused the surface trough in the eastern Caribbean Sea to strengthen into a broad surface low pressure spin centered near the eastern tip of the Dominican Republic as of this writing. The expansive upper divergence zone is also producing a sprawling comma shaped region of thunderstorms which is now lifting northward into the western Atlantic after earlier affecting the northeastern Caribbean islands with heavy rainfall. The increasingly defined surface spin along with the increasingly consolidated and organizing comma-shaped cloud mass... along with ongoing high computer model support... suggest subtropical cyclone formation of this system is very likely within the next few days. As such I have begun a subtropical cyclone formation forecast with specific track and intensity points as outlined below. The initial subtropical designation of this system is due to its hybrid nature... with the surface low pressure spin to be supported by a combination of the divergence zone on the east side of the cold core upper vortex and the warm core upper outflow to be induced by the thunderstorm latent heat release of the comma-shaped region of thunderstorm activity.
This system is expected to initially track north around the east side of the upper vortex... then curve westward toward the northwestern Bahamas and Florida peninsula while steered between the north side of the upper vortex and south side of the current western Atlantic deep-layer ridge. The westward swing in track is expected to continue through day 4 as another unseasonably warm deep-layer ridge develops over Canada in the warm sector of a vigorous frontal system to develop over the western US. The Canadian ridge is also expected to trap the south fragment of the current central US upper trough near ex-Lisa in the eastern Gulf of Mexico... with this energy potentially merging with the west side of the upper vortex to re-enforce the upper vortex which will all the more help promote the westward track. I have made some small adjustments to the westward arcing track... initially electing a more north position for the 48 hour forecast point as the lastest model runs indicate the south part of the upper trough associated with area of interest #45 will merge with the northwest part of the upper vortex... and before the merge produce a northward-located upper divergence maximum that would act to both attract and then potentially strengthen the surface cyclone. Between 48 and 72 hours the track is then deflected back west-southwest to the previous forecast due to the strength of the approaching Canadian deep-layer ridge... with an increase in forward speed that takes this system near/over the northwestern Bahamas and then Florida peninsula by day 4 as this deep-layer ridge takes over the steering. The vigorous western US frontal system and associated amplified upper trough then makes its approach by 5+ days to bend the track of this system north. There is some uncertainty as to when exactly the north turn occurs as this will depend on exactly how fast the upper trough approaches... a slower approach will result in a later north turn across the Florida peninsula or far eastern Gulf of Mexico and a faster approach will result in a sooner north turn just east of the peninsula and toward/along the Georgia/Carolina coast. Noting as of late the longer-term model consensus is shifting toward the sooner turn... however the model consensus could shift again and so as usual the longer-range forecast track has some uncertainty.
Regarding forecast intensity... I forecast a high-end subtropical cyclone by 48 hours as decent strengthening of the surface low pressure/cyclone is anticipated due to the expansive eastern divergence zone of the cut-off upper vortex... along with a potential second dose of upper divergence from the south fragment of the upper trough near area of interest #45 that gets ingested into the northwest side of the upper vortex. By 72 hours... as we see with any typical post-mature non-tropical or subtropical system the surface circulation then whirls into the core of the upper vortex where upper divergence is lacking and therefore I taper off the strengthening rate between 48 and 72 hours. In the 72+ hour window... thunderstorms in the circulation will be supported by water temps above 26 deg C... and will also be able to stay stacked vertically in a low shear environment caused by deep-layer cyclonic flow caused by the combo of the surface subtropical circulation and upper vortex... potentially allowing for the formation of a fully tropical core to the subtropical circulation that establishes warm anticyclonic outflow below the upper vortex and supported by the thunderstorm latent heat release. I think the chances of a fully tropical core are high for this system as it will be left undisturbed to the south of unseasonably warm deep-layer ridges for much of the forecast period such that it will have plenty of time to obtain its fully tropical core. As a result I forecast the core of this system to transition into a strengthening hurricane by day 4. For now the forecast track takes this system into the Florida peninsula... therefore weakening is shown in the forecast track by day 5.
Regarding impact to land areas:
(1) The thunderstorm activity of this system has consolidated to the north of the northeastern Caribbean Islands (Dominican Republic to Lesser Antilles) as this system becomes better organized which is bringing an end to rainfall over the islands. Noting that a mid-level trough of low pressure remains defined near the north coast of Colombia by a band of vorticity in the CIMSS 850 mb product (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) and associated band of thunderstorms... the remnants of what was tagged area of interest #46 in the previous blog post. This mid-level trough could be flung northeastward into the islands by the deep-layered cyclonic circulation of this system... it is possible while over the islands this trough becomes enhanced by the eastern divergence zone of the upper vortex which would result in a second round of rainfall. Any rainfall that develops could result in flash flooding potential over grounds already soaked/saturated by this system.
(2) Due to the large outer circulation of this system... a large area of wind blowing toward shore could produce notable coastal surf for the northwestern Bahamas as well as the southeast US coast from the Carolinas to east coast of Florida by Wednesday and Thursday. Gusty winds could also spread onshore during this timeframe.
(3) Confidence is increasing that the core of this system could transition into a strengthening hurricane... as a result chances are increasing that more significant wind and coastal storm surge affects the northwestern Bahamas and Florida peninsula by Thursday and Friday. Interests here should be aware of this system... preparations for this system maybe required Tuesday and Wednesday if the current forecast holds (for the Florida peninsula... that means on and after election day).
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0600Z Nov 6)... Surface low located just south of the eastern Dominican Republic near 17.8N-69W
IOH 24 Hr Forecast (0600Z Nov 7)... Subtropical surface low centered in the western Atlantic near 24.5N-67.5W
IOH 48 Hr Forecast (0600Z Nov 8)... 60 mph maximum sustained wind subtropical storm centered in the western Atlantic at 28N-71W
IOH 72 Hr Forecast (0600Z Nov 9)... 65 mph maximum sustained wind tropical storm centered in the western Atlantic at 27.5N-74.5W
IOH 96 Hr Forecast (0600Z Nov 10)... 85 mph maximum sustained wind hurricane centered just north of the northwestern Bahamas and east of the Florida peninsula at 27.5N-78.5W
IOH 120 Hr Forecast (0600Z Nov 11)... 60 mph maximum sustained wind tropical storm centered over the northwestern Florida peninsula at 29.2N-83W
AREA OF INTEREST #45...Colorized infrared image of the surface frontal low pressure area in the open central Atlantic located well east of Bermuda and showing signs of tropical characteristics while featuring a thunderstorm mass and well-defined surface rotation beneath... image taken on Saturday November 5 at 1950Z. Red arrow points to the center of surface rotation:
The frontal low pressure area in the open central Atlantic spent much of Saturday making a run for tropical cyclone status while firing persisting thunderstorms over its surface spin featuring latent heat release driven upper outflow to the east of its parent upper trough. Upper westerly flow then increased directly over the surface spin as the parent upper trough was pushed closer by the deep-layer ridge that has recently entered the western Atlantic from eastern North America... and also due to the outflow of the sprawling thunderstorm activity to the southwest associated with area of interest #44. This upper westerly flow has displaced the thunderstorm activity east of low-level cloud swirl associated with the surface circulation... just in time to prevent tropical cyclone formation. This system also has not moved as far to the west as previously forecast... perhaps as the circulation became stronger/taller while it tried to develop on Saturday such that it coupled with the upper westerly flow which in turn shunted the circulation eastward. Also noting that the slightly more north position of this system along 32N latitude instead of yesterday's 31N latitude (32N-53.5W as of 0600Z) suggests this system has become trapped in a notch of surface low pressure within the aforementioned deep-layer ridge and induced by the eastern divergence zone of the parent upper trough. Being within such a notch prevents this system from moving freely westward around the southern periphery of the ridge. As a result the model projections and updated forecast track has taken a notable eastward shift. The forecast track still calls for this system to anticyclonically curve around the deep-layer ridge as the ridge passes to the north of this system... with this system ultimately curving eastward in the long range (48+ hours) in the flow ahead of a high-latitude upper trough to approach from its current position over western Canada.
Given the early increase in westerly wind shear... I have now dropped my peak odds of tropical cyclone formation to 50%... with the odds continuously tapered down from the peak going forward as the forecast track takes this system over increasingly cooler water with time. Although this system has drifted into water temps below 26 deg C... I still have development odds above 0% as the divergence zone of the nearby parent upper trough may aid in thunderstorm generation... as such my 48-hour forecast point also leans toward the location of this trough's divergence maximum from this past 0000Z GFS model run. The shear may also not be prohibitvely high for tropical development... especially as the anticyclonically curving track increasingly aligns the forward motion of this system with the upper westerly flow. Odds of tropical development are droppped to 0% at 72 hours once this system is overran by the cold front of the high-latitude upper trough.
On a final note... the potential for this system to produce coastal surf to the island of Bermuda has dropped with the latest shift in the forecast track.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0600Z Nov 7)... 50% chance of tropical cyclone formation (central Atlantic near 32.5N-56W)
IOH 48 Hr Outlook (0600Z Nov 8)... 40% chance of tropical cyclone formation (central Atlantic near 35N-54.5W)
IOH 72 Hr Outlook (0600Z Nov 9)... 0% chance of tropical cyclone formation (north Atlanitc near 41N-40W)
AREA OF INTEREST #47...A tropical wave of low pressure in the open central Atlantic... located along 42W longitude as of this writing... is taking advantage of an upper outflow environment caused by a regional upper ridge cell while producing organized squalls of thunderstorm activity. Over the next five days... the upper ridge cell is forecast to expand as the upper vortex associated with area of interest #44 moves westward and away while also weakening out of isolation from high-latitude cold air. Intermittently recent runs of the GFS model suggest that this tropical wave could develop under this favorable upper air pattern... and as of late the NAVGEM seems to also hint at this tropical wave developing into a tropical low pressure. Given all of the above... I have added this tropical wave as an area of interest for tropical development... making this the forty-seventh tropical Atlantic area of interest I have tracked on this blog this year.
This tropical wave is expected to continue west toward Trinidad and Tobago... the southern Lesser Antilles... and southeastern Caribbean Sea at varying speeds over the next five days. The forward speed slows a bit at 72 hours as the current deep-layer ridge moving into the Atlantic and associated surface easterly trade winds weakens once the current west Canada upper trough moves into the Atlantic. After the trades recover at 96 hours with the approach of another deep-layer ridge from Canada... this system is likely to slow down again at 120+ hours once encountering another area of weaker trades associated with the surface ridge weakness created by area of interest #44. In this update I have already assigned a 30% peak odds of tropical cyclone formation given the organized thunderstorm activity and favorable upper wind outlook that lies ahead. I did not select higher odds as model support is lacking... should this system become better organized or later model support develops then odds of development will be increased in future updates. Regardless of tropical cyclone formation or not... the southern Lesser Antilles... Trinidad and Tobago... and northeastern Venezuela may see heavy rainfall and gusty winds from this system by Thursday and Friday.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0600Z Nov 7)... 0% chance of tropical cyclone formation (central tropical Atlantic near 8.5N-47W)
IOH 48 Hr Outlook (0600Z Nov 8)... 10% chance of tropical cyclone formation (central tropical Atlantic near 9.5N-52W)
IOH 72 Hr Outlook (0600Z Nov 9)... 20% chance of tropical cyclone formation (east of Trinidad and Tobago near 10N-56W)
IOH 96 Hr Outlook (0600Z Nov 10)... 30% chance of tropical cyclone formation (Trinidad and Tobago near 11N-61W)
IOH 120 Hr Outlook (0600Z Nov 11)... 30% chance of tropical cyclone formation (southeastern Caribbean Sea offshore of northeastern Venezuela near 11.5N-64W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Nov 5) CMC Model Run...
**For area of interest #44... center of broad eastern Caribbean surface low passes between Puerto Rico and the Virgin Islands at 18 hours... subtropical cyclone formation suggested near 26.5N-71W at 66 hours... subtropical cyclone continuously strengthens while swinging west with center arriving to a position just north of the northwestern Bahamas and just east of Cape Canaveral Florida at 120 hours.
**For area of interest #45... while surface low curves north in track becomes a tropical cyclone near 35.5N-53.8W at 66 hours... upper trough to approach from its current western Canada position recurves the tropical cyclone eastward with cold front driven by the upper trough causing a loss in tropical characteristics while cyclone located near 37N-47.5W at 78 hours... cyclone loses identity on the cold front while located near 47N-26W at 102 hours.
**For area of interest #47... no development shown
1200Z (Nov 5) ECMWF Model Run...
**For area of interest #44... broad surface low forms near 21.5N-68.5W at 30 hours... broad surface low gradually strengthens and develops a better defined center over the northwestern Bahamas at 102 hours suggesting subtropical cyclone formation... center of subtropical cyclone moves into the southern Florida peninusla by 126 hours.
**For area of interest #45... surface low curves north to 33N-54W at 66 hours... upper trough to approach from its current western Canada position recurves the surface low eastward with cold front driven by the upper trough absorbing the surface low while located near 35N-47.5W at 84 hours.
**For area of interest #47... no development shown
0000Z (Nov 6) GFS Model Run...
**For area of interest #44... surface low develops near 21N-66W at 12 hours... subtropical cyclone formation suggested near 25N-70W at 36 hours... cyclone continuously strengthens while swinging west and moves into the northwestern Bahamas at 90 hours... makes landfall on east coast of Florida peninsula just south of Cape Canaveral at 114 hours... center of cyclone located over the central Florida peninsula at 120 hours.
**For area of interest #45... surface low curves north to 35N-56W at 51 hours... upper trough to approach from its current western Canada position recurves the surface low eastward with cold front driven by the upper trough absorbing the surface low while located near 41.5N-40.2W at 78 hours.
**For area of interest #47... no development shown
1800Z (Nov 5) NAVGEM Model Run...
**For area of interest #44... broad surface low develops over Puerto Rico at 12 hours... subtropical cyclone formation suggested near 24.5N-68W at 36 hours... cyclone continuously strengthens while swinging west and reaches a postion north of the northwestern Bahamas and east of the Florida peninsula near 28.8N-77W at 120 hours.
**For area of interest #45... surface low weakens to a trough near 32N-54.5W at 24 hours.
**For area of interest #47... no development shown