MY 2023 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #120
Updated: Nov 13
*******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.*********
...UPDATE...MONDAY NOVEMBER 13 2023 9:30 AM EDT...
The birdseye view chart below has been updated to include the surface and upper air analysis for 1200Z November 12 which were effective at the time the forecasts and discussions below were created.
...SATURDAY NOVEMBER 11 2023 5:12 PM EDT...
Note the usual surface and upper air analysis are not included in the above chart to ensure a more timely release of this update... those parts of the chart will be added within the next several hours.
Over the next few days a tropical disturbance with development potential is expected to emerge in the central Caribbean Sea... see area of interest #53 section below for more information including expected impacts to surrounding land areas. Elsewhere... no other tropical areas of interest are expected to emerge in the Atlantic basin.
AREA OF INTEREST #53... Cold core upper vorticity currently parked over the north-central Caribbean islands is in the process of decaying while isolated from high-latitude cold air... and over the next couple of days will become replaced by the warm core upper ridge now approaching from the northwestern Caribbean. Thunderstorm activity has increased in the south-central Caribbean just north of Panama in split flow upper divergence between the approaching upper ridge and decaying upper vorticity where a tropical disturbance is likely to materialize. Because this location is southwest of my previous forecast the updated forecast below is adjusted accordingly. The forecast track continues to call for an initial west drift toward Central America under the influnce of strong surface ridge now settling over eastern North America... followed by an increasing northward and then northeastward turn as the regional flow reverses from the approach of a southern stream upper trough and Gulf of Mexico surface frontal low generated by the divergence zone of the upper trough. The long-term forecast track is more eastward and less northward as the southward-adjusted forecast track aligns this disturbance toward the south side of the upper trough/surface frontal low where the steering flow is more westerly and less southerly. Although the long-term westerly shear forecasts have reduced with the models showing a more amplified upper trough... this system is still at risk of becoming an enlarged tropical low with multiple centers... instead of a single center needed for tropical cyclone formation... due to the size of the incoming upper trough’s divergence zone. As a result I have not increased my peak odds of tropical cyclone formation above 20% in this update cycle. Note the 96 hour forecast point is over land… however odds of development are above 0% in the event offshore thunderstorm bands develop tropical cyclone force winds.
Regardless of tropical cyclone formation or not... expect periods of increasing rainfall for Nicaragua as well as eastern and central Honduras by Monday thru Wednesday. By late in the week a large area of heavy rainfall overspreading Jamaica and eastern Cuba appears the most likely scenario… the more east and less north long range forecast track has reduced the long range rainfall potential for the Cayman Islands.
IOH 24 Hr Outlook (1200Z Nov 12)... 0% chance of tropical cyclone formation (south-central Caribbean near 11.5N-80W)
IOH 48 Hr Outlook (1200Z Nov 13)... 0% chance of tropical cyclone formation (offshore of southeastern Nicaragua near 11.5N-81.5W)
IOH 72 Hr Outlook (1200Z Nov 14)... 20% chance of tropical cyclone formation (southeast coast of Nicaragua near 12N-84W)
IOH 96 Hr Outlook (1200Z Nov 15)... 20% chance of tropical cyclone formation (northeastern Nicaragua near 14N-84W)
IOH 120 Hr Outlook (1200Z Nov 16)... 20% chance of tropical cyclone formation (offshore and east-northeast of Honduras near 15.5N-82W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 1 PM EDT***************************
Formation chance through 48 hours... 0%
Formation chance through 7 days... 30%
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields(http://moe.met.fsu.edu/tcgengifs/).
0000Z (Nov 11) CMC Model Run...
**For area of interest #53... no development shown
0000Z (Nov 11) ECMWF Model Run...
**For area of interest #53... becomes a better-defined tropical low in the south-central Caribbean Sea near 12.5N-80W at 126 hours... becomes generally stationary through 168 hours due to the narrow ridge weakness of a frontal low to the north that moves from the northern Gulf of Mexico to the waters offshore of the southeastern US
0600Z (Nov 11) GFS Model Run...
**For area of interest #53... becomes a better-defined tropical low just offshore of northeastern Nicaragua at 90 hours... tropical cyclone formation suggested just offshore of the Nicaragua/Honduras border at 105 hours... due to passage of frontal low to the north the gradaully strengthening tropical cyclone accelerates eastward and passes just south of Jamaica at 150 hours then northeastward into Haiti through 168 hours
0600Z (Nov 11) NAVGEM Model Run...
**For area of interest #53... becomes a better-defined tropical low over the Caribbean Sea and just northeast of the Nicaragua/Honduras border at 108 hours... moves east-northeast into Jamaica... eastern Cuba... and northwestern Bahamas through 138 hours while becoming a large/broad system with multiple centers and becoming entangled with developing frontal low to the north... shortly after that time the frontal low becomes the dominant feature in the region while strengthening into a large western Atlantic frontal cyclone.