MY 2024 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #6

*******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.*********

...FRIDAY MAY 31 2024 2:18 PM EDT...

The Atlantic Hurricane Season officially begins tomorrow... therefore at this point will be issuing daily updates on the Atlantic tropics until the season ends in November.

See area of interest #3 section below for a final update on the southern Caribbean disturbance which has recently made landfall across Nicaragua.

For the mid-latitudes of the Atlantic... a quasi-stationary cut-off deep-layer low pressure continues west-northwest of the Azores due to upstream warm core deep-layer ridging spreading across the north Atlantic. Although the upper-layers of this circulation remain cold (200 mb heights of 1189 dekameters)... this system is parked over waters just below 20 deg C resulting in an instability profile not sufficient for tropical development. The models are in agreement that the current upper trough/surface frontal system now departing eastern North America will evolve into a second cut-off deep-layer low pressure in the northwest Atlantic in the days ahead as warm core deep-layer ridging prevails across the far north Atlantic in the warm sector of frontal systems to slide across Canada. Because the forecast northwest Atlantic cut-off low will be further west toward warmer Gulf Stream waters... it has more potential to have instability needed for transition into a tropical system. However not declaring a new tropical area of interest for the northwest Atlantic at this time as the model also agree the upper-layers of the northwest Atlantic system and current system west-northwest of the Azores merge... resulting in a lack of focused upper divergence needed to trigger a well-defined northwest Atlantic surface center that would be required for tropical development.

For the eastern and central tropical Atlantic... surface tropical waves of low pressure are present at 47.5W longitude and at 27.5W longitude as of this writing. These waves were once unusually robust for late May while each having a well-defined thunderstorm cluster... however recently these waves are now weaker and more seasonable while succumbing to westerly wind shear imparted by the current central Atlantic upper trough and regional dry Saharan air. Based on another round of concentrated thunderstorms currently departing the west coast of Africa... it appears another robust tropical wave of low pressure is about to enter the eastern tropical Atlantic. Through June 5th the models show the shearing central Atlantic upper trough weakening while remaining cut-off from high-latitude cold air... and this would be the best time for any of these unusually-robust waves to develop in the central or eastern tropical Atlantic in June... earlier than normal in the Atlantic hurricane season. This would also require the dry Saharan air to abate which is not guaranteed. After that time the forecast northwest Atlantic deep-layer low pressure system mentioned in the previous paragraph is forecast to pump warm air into the mid-latitudes of the central Atlantic... resulting in a warm core upper ridge that pushes the remnants of the central Atlantic upper trough into the central and eastern tropical Atlantic where they would suppress tropical activity as a string of upper vorticity promoting overhead upper convergence. Given the narrow window of favorable atmoshperic conditions toward June 5th and possible dry Saharan air... not declaring any areas of interest for the eastern or central tropical Atlantic at this time.

AREA OF INTEREST #3... Over the last day the mid-level low pressure rotation that was in the southern Caribbean appears to have made landfall across Nicaragua as long-term satellite loops show rotating clouds now over land. The CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) shows no appreciable mid-level spin over Nicaragua and therefore there is no longer a feature I can use to define this area of interest going forward... therefore will be my final statement on this area of interest.

For the longer-term... some previous model runs suggested the remnants of this disturbance would accelerate northeastward across the northern Caribbean Islands and into the western Atlantic while transitioning into a feature supported by the divergence zone of an upper trough that will be emerging from the southeastern US in 72+ hours. With this area of interest now dissipated (no longer having a low pressure feature I can used to define it)... whatever western Atlantic disturbance the upper trough would produce in the future would be considered a new seperate area of interest. Recent GFS model runs suggest tropical development associated with this upper trough... however given that the upper trough is forecast to be of low amplitude in the GFS and other models it is more likely that the trough would induce excess westerly shear unfavorable for tropical development. Therefore not declaring a western Atlantic tropical area of interest at this time.

...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).

0000Z (May 31) CMC Model Run...

**For area of interest #3... no development shown

0000Z (May 31) ECMWF Model Run...

**For area of interest #3... no development shown

0000Z (May 31) GFS Model Run...

**For area of interest #3... no development shown

**Upper trough moves offshore of southeastern US at 72 hours... eastern divergence zone of trough triggers surface low east of the eastern Bahamas and near 21.2N-69W at 120 hours with tropical cyclone formation suggested near 24N-65W at 129 hours... tropical cyclone continues east-northeast to 28N-50W through 165 hours

0600Z (May 31) NAVGEM Model Run...

**For area of interest #3... no development shown