*******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.*********
...WEDNESDAY NOVEMBER 1 2023 1:09 PM EDT...
The Atlantic tropics finally show signs of slowing down as we start the month of November with only one area of interest remaining:
(1) The remaining area of interest is a broad surface low pressure system currently located in the central Caribbean Sea near Haiti and Jamaica. This feature has a medium chance at tropical cyclone formation while forecast to move west-southwest into Central America... see area of interest #51 section below for more information.
(2) The remnant low pressure swirl of Tammy... located in the open central Atlantic... has not re-developed thunderstorm activity and time has ran out for it to re-develop. See area of interest #52 section below for a closing statement on ex-Tammy.
AREA OF INTEREST #51... The Caribbean surface low that has been near Jamaica is merging with the additional surface low that has been approaching from the eastern Carribean at a location south of Haiti based on the position of the associated thunderstorm activity. This position is a little west of my previous forecast track and so my updated one is adjsuted accordingly. A west-southwest track of the merged system toward Central America is expected through 72 hours under the influence of the rather strong surface ridge now approaching from the central US. Even if this system were to become stronger/taller to couple with upper winds... the initial south slant in the forecast track from the push of the strong surface ridge will move this system into the south side of the current Caribbean upper ridge where the upper flow is forecast to also be east-northeasterly (ENE)... particularly as some of the current central tropical Atlantic upper vorticity tries to retrograde around the south side of the Caribbean upper ridge and toward this system... with the incoming upper vorticity from the east modulating the upper wind vectors from easterly (E) to east-northeasterly (ENE). Regarding peak odds of tropical cyclone formation... satellite animation as of this writing does not show a well-defined rotation in association with the thunderstorm activity and so I have not raised them above 40%. I have also lowered the short-term odds of tropical cyclone formation. Peak odds below 50% also makes sense to me as this system may struggle to develop a well-defined center while in an initially broad state caused by the merger between the two surface lows as noted above... and as this system may have to contend with ENE shear while being on the south side of the Caribbean upper ridge cell rather than underneath it. The global models may be picking up on these negative factors as many members are not developing this system. Noting between 72 to 120 hours the forecast track is more westward into Central America instead of continuing west-southwest as the steering surface ridge shifts east which causes this system to begin rounding the southwest side of the ridge. The Caribbean upper ridge also shifts south and becomes more stacked with this system due to the push provided by a series of upper troughs passing over North America. I have odds of tropical cyclone formation above 0% by 96 and 120 hours despite landfall with Central America as this system may still be large/broad enough to take advantage of the low shear/outflow below the Caribbean upper ridge's core to develop into a tropical cyclone centered over land with offshore western Caribbean squalls containing the gusty winds. If development does not occurr toward the Caribbean side of Central America... it is possible this system in the long range goes on to trigger development toward far eastern Pacific side of Central America.
The short-term potential for heavy rainfall appears concentrated toward Haiti and Jamaica as the thunderstorm shield on satellite pictures is not covering the Dominican Republic nor eastern Cuba. By days 3 and 4 the rainfall potential shifts southwest toward Nicaragua and Honduras... this is also the area most likely to see tropical cyclone impacts (gusty winds and coastal surf) should tropical cyclone formation in fact occur. The potential for possible tropical cyclone impacts extends westward into Belize and Guatemala by day 5... with heavy rainfall possible as far south as El Salvador.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Nov 2)... 0% chance of tropical cyclone formation (southeast of Jamaica near 15.5N-75W)
IOH 48 Hr Outlook (1200Z Nov 3)... 20% chance of tropical cyclone formation (central Caribbean near 15N-79W)
IOH 72 Hr Outlook (1200Z Nov 4)... 40% chance of tropical cyclone formation (just offshore of northeastern Nicaragua near 14.5N-82.5W)
IOH 96 Hr Outlook (1200Z Nov 5)... 30% chance of tropical cyclone formation (inland and just west of the Nicaragua/Honduras border near 14.5N-86W)
IOH 120 Hr Outlook (1200Z Nov 6)... 30% chance of tropical cyclone formation (western Honduras near 14.5N-88.8W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT***************************
Formation chance through 48 hours... 20%
Formation chance through 7 days... 50%
AREA OF INTEREST #52 (REMNANTS OF TAMMY)... The remnant cloud swirl low pressure of Tammy... located at 25N-54W as of 1200Z today... continues west in the open central Atlantic while pushed around the deep-layer ridge passing to the north. Despite moving into lower shear and upper outflow beneath the upper layers of the ridge... so far the circulation has not re-developed thunderstorm activity. Going forward the circulation is expected to bend increasingly north in track while rounding the back western side of the passing deep-layer ridge... thus this system only has 24 more hours in the low shear/outflow environment before moving into hostile shearing mid-latitude upper westerlies. This is too short of a timeframe for ex-Tammy to make a comeback as a tropical cyclone even if it were to re-develop thunderstorms now as the initial state of the circulation at this point is quiet weak. Therefore this is my final statement regarding ex-Tammy on this blog.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
IOH 24 Hr Outlook (1200Z Nov 2)... 0% chance of tropical cyclone formation (central Atlantic near 28N-57W)
******National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT***************************
Not in the official outlook
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields(http://moe.met.fsu.edu/tcgengifs/).
0000Z (Nov 1) CMC Model Run...
**For area of interest #51... no development shown
**For area of interest #52... remnant low of Tammy weakens to a trough near 25N-54W at 18 hours... trough dissipates shortly thereafter
0000Z (Nov 1) ECMWF Model Run...
**For area of interest #51... no development shown
**For area of interest #52... remnant low of Tammy weakens to a trough near 25N-54W at 18 hours... trough dissipates shortly thereafter
0600Z (Nov 1) GFS Model Run...
**For area of interest #51... coalesces into a better-defined tropical low just offshore of northeastern Nicaragua through 72 hours... makes landfall in Central America and dissipates shortly thereafter
**For area of interest #52... remnant low of Tammy weakens to a trough near 25N-55W at 12 hours... trough dissipates shortly thereafter
0600Z (Nov 1) NAVGEM Model Run...
**For area of interest #51... coalesces into a better-defined tropical low near 13N-77.5W at 54 hours... makes landfall on east coast on Nicaragua by 90 hours and dissipates shortly thereafter
**For area of interest #52... remnant low of Tammy weakens to a trough near 25N-56W at 6 hours... trough dissipates shortly thereafter