*******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.*********
...UPDATE...SUNDAY OCTOBER 20 2024 1:33 PM EDT...
The surface and upper air charts valid for October 19 have been added below.
...SATURDAY OCTOBER 19 2024 1:10 AM EDT...
As we progress into the latter half of October... still monitoring multiple areas of interest for tropical development in the Atlantic basin as follows:
(1) A northeastern Caribbean tropical wave of low pressure which remains at risk of tropical cyclone formation while moving toward the southeast Bahamas... eastern Cuba... and Jamaica... see area of interest #40 section below for details.
(2) A broad area of low pressure in the western Caribbean which is at high risk of tropical storm formation before landfall near the Belize/Mexico border region during the overnight hours and into tomorrow morning... see area of interest #43 (potential tropical cyclone fifteen) section below for more information.
(3) The surface cyclone currently northwest of Bermuda has ran out of time to develop tropical character... this system will quickly weaken under unfavorable upper winds while moving south across Bermuda within the next 24 hours... see area of interest #43 section below for more information.
(4) As noted in the area of interest #40 discussion below... cut-off upper vorticity will persist in the western Atlantic for a few days while re-enforced by packets of energy deposited by passing high-latitude upper troughs from North America. If the upper vorticity eventually evolves into a configuration with low enough westerly shear and high enough upper divergence on its east side... it could support a broad surface low pressure area with tropical characteristics between Bermuda and the northern Caribbean Islands sometime this upcoming week (the broad low pressure area may also contain the remnants of area of interest #40 and #43). Will add an area of interest in future updates for this region if needed.
AREA OF INTEREST #40... For the tropical wave of low pressure that was in the central tropical Atlantic… and now over the northeastern Caribbean Islands… southeasterly shear imparted by the lingering upper vorticity in the eastern Caribbean appears to have caused the original low-level center to dissipate while a new one has formed to the north and west in the midst of the curved thunderstorm bands… and my updated forecast track in the outlook below is adjusted accordingly. The curvature of the thunderstorm bands and CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) has the new low-level center positioned north-northwest of Puerto Rico as of 0000Z tonight. Models are in good agreement on bringing the center west then west-southwest near the southeast Bahamas and into southeastern Cuba through 48 hours… under the influence of the strong eastern US surface ridge as it expands into offshore western Atlantic waters. Beyond that time models are split on the track of this system… some continue this system west-southwest across the northwest Caribbean under the influence of the surface ridge… and others have this system undergo a counter-clock loop in the vicinity of southeast Cuba and the southeast Bahamas… then turn northeast into the west Atlantic into an expanding surface ridge weakness generated by the divergence zone of the current west Atlantic upper vorticity… particularly as the upper vorticity is expanded 120 hours by energy deposited by a passing high-latitude upper trough from North America. My updated forecast track is a compromise between these two ideas… showing this system stalling between Jamaica and eastern Cuba during days 3 to 5 and in between the conflicting steering influences. Regarding development potential... given the current organization and given the updated track keeps this system closer toward low shear/outflow of the western Caribbean upper anticyclone… I have raised my peak odds of tropical cyclone formation to 80%. I dip the odds briefly to 70% at 48 hours due to land interaction with southeast Cuba… then again dip the odds by 120 hours as the probability of northerly shear increases as the west Atlantic upper vorticity expands as noted above.
Regarding impact to land areas:
(1) The northeast Caribbean Islands from the northern Lesser Antilles to Hispaniola have dodged impacts from this system due to the north reformation of the best-defined center as discussed above.
(2) Interests in eastern Cuba… Jamaica… and the southeast Bahamas should now be aware of possible tropical cyclone impacts (heavy rain… gusty winds… and coastal surf) through early this upcoming week… particularly as this system could track erratically in this region as discussed above.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Oct 20)… 80% chance of tropical cyclone formation (between Hispaniola and the southeastern Bahamas near 20.2N-71.5W)
IOH 48 Hr Outlook (0000Z Oct 21)… 70% chance of tropical cyclone formation (southeastern coast of Cuba near 20N-75W)
IOH 72 Hr Outlook (0000Z Oct 22)… 80% chance of tropical cyclone formation (just offshore of the north coast of Jamaica near 19N-77W)
IOH 96 Hr Outlook (0000Z Oct 23)… 80% chance of tropical cyclone formation (just offshore of the north coast of Jamaica near 19N-77W)
IOH 120 Hr Outlook (0000Z Oct 23)… 60% chance of tropical cyclone formation (just offshore of the north coast of Jamaica near 19N-77W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT*************************
Formation chance through 48 hours... 30%
Formation chance through 7 days... 30%
AREA OF INTEREST #42 (POTENTIAL TROPICAL CYCLONE FIFTEEN)… The broad western Caribbean tropical low pressure offshore of Honduras and Belize has continued to organize… and appears to in the process of developing a well-defined center… as such the NHC has upgraded this area of interest to a potential tropical cyclone in order to issue tropical storm watches for northern Belize and southern Quintana Roo ahead of time. This system is expected to continue west into this area… and then further west eventually toward the Isthmus of Tehuantepec… under the steering influence of the strong eastern US surface ridge. Conditions are becoming increasingly favorable for tropical development as the western Caribbean upper anticyclone (featuring low shear and outflow) is being allowed to expand in the wake of the east-shifting west Atlantic upper vorticity. However the upper anticyclone may not expand fast enough to end the slightly disruptive southerly shear ongoing on the west side of the upper anticyclone… therefore intensity no higher than a low-end tropical storm is expected for tomorrow morning’s landfall at the Belize/Quintana Roo border regions. After landfall… the broad remnant low may re-develop a best-defined center over offshore Bay of Campeche or eastern Pacific waters during the late weekend or early part of this upcoming week… if this occurs will extend my forecast points beyond October 20 to cover potential Bay of Campeche re-development of this system in future updates (meanwhile any eastern Pacific tropical development is not covered on this site... information on eastern Pacific activity is on the NHC site... hurricanes.gov).
Regarding impact to land areas:
(1) Expect heavy rainfall (with flash flood potential) and gusty winds to increase in the overnight and morning hours across northern Belize and southern Quintana Roo… aforementioned southerly shear may spread the thunderstorms and heavy rainfall across the remainder of Quintana Roo and Yucatan provinces.
(2) Expect heavy rainfall (with flash flood potential) across Campeche… Tabasco… Chiapas… northern Guatemala… eastern Veracruz… and eastern Oaxaca late this weekend through early next week. Eastern Veracruz could see gusty winds if this system tries to re-develop in the Bay of Campeche… and likewise for eastern Oaxaca if re-development occurs on the eastern Pacific side.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Oct 19)… Tropical low centered in the western Caribbean at 17.5N-85.7W
IOH 12 Hr Forecast (1200Z Oct 19)... 45 mph maximum sustained wind tropical storm making landfall near the Belize/Mexico border while centered at 17.5N-88W
IOH 24 Hr Forecast (0000Z Oct 20)… Remnant low centered over the Guatemala/Mexico border at 17.5N-91W
*****National Hurricane Center (hurricanes.gov) official forecast as of 11 PM EDT*************************
Peak Strength (1200Z Oct 19)… 40 mph maximum sustained wind tropical storm centered just offshore of northern Belize at 17.5N-87.5W
1-Day Position (0000Z Oct 20)… 35 mph maximum sustained wind dissipating tropical depression centered over northern Guatemala at 17.3N-90W
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT*************************
Formation chance through 48 hours... 70%
Formation chance through 7 days... 70%
AREA OF INTEREST #43... The western Atlantic surface cyclone northwest of Bermuda is already diving south toward Bermuda while coming under the influence of the strong eastern US surface ridge… and as of 0000Z the center passed 36N-66W. The cyclone has peaked in intensity while now decoupling from the supporting overhead upper vorticity on its current track… and will be decaying to a quickly fading surface low under suppressing upper convergence on the back side of the east shifting upper vorticity. These oppressive upper winds will also make it unlikely that thunderstorms and tropical development occurs… thus this will be my final statement on this area of interest on this blog.
Coastal surf for Bermuda and the mid-Atlantic coast of the United States should fade in the coming hours as the surface circulation rapidly weakens. Direct impacts to Bermuda such as gusty winds and heavy rain appear unlikely as the surface low will be far along in its decay phase... with shower and thunderstorm generation being capped by aforementioned upper convergence as this system slides across Bermuda.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Oct 20)... 0% chance of subtropical cyclone formation (just south-southwest of Bermuda near 31.5N-65.5W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM 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/).
1200Z (Oct 18) CMC Model Run…
**For area of interest #40… after crossing the northern Caribbean islands… dives SW across NW Caribbean and toward north coast of Honduras by 144 hours… a loses identity soon after
**For area of interest #42… makes landfall on Belize coast as a possible tropical cyclone at 24 hours… inland remnants proceed to lose their identity over SE Mexico through 84 hours
**For area of interest #43… dissipates SW of Bermuda by 60 hours
1200Z (Oct 18) ECMWF Model Run…
**For area of interest #40… possible compact tropical cyclone formation between SE Bahamas and east Cuba at 48 hours… weakens to a remnant low while moving SW across the eastern tip of Cuba through 72 hours… possibly regains compact tropical cyclone status while reversing NNE across SE Bahamas through 114 hours shortly after which time it transitions to an elongated remnant low… by 144+ hours while located just SE of Bermuda the elongated remnant low loses identity to new frontal low developing to the northeast
**For area of interest #42… makes landfall over northern Belize still as a tropical low at 30 hours… inland remnants proceed to lose their identity over SE Mexico through 84 hours
**For area of interest #43… dissipates SW of Bermuda by 60 hours
1800Z (Oct 18) GFS Model Run…
**For area of interest #40… no development shown
**For area of interest #42… makes landfall over northern Belize still as a tropical cyclone at 21 hours… inland remnants proceed to lose their identity over SE Mexico through 69 hours
**For area of interest #43… dissipates SSW of Bermuda by 69 hours
1800Z (Oct 18) NAVGEM Model Run…
**Not available at above mentioned source
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