*******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.**********
...SATURDAY AUGUST 13 2022 11:00 AM EDT...
While the eastern and central tropical Atlantic remain calm due to an outbreak of dry saharan air... attention turns to the western part of the Atlantic basin for potential tropical development as follows:
(1) A tropical low pressure area in the northwestern Gulf of Mexico now advancing westward toward southern Texas... see area of interest #15 section below for more information.
(2) A large upper trough and surface frontal system has recently entered the western Atlantic from eastern North America. The southern portion of this system may evolve into a subtropical or tropical disturbance offshore of the southeastern United States... which will move northeastward into the waters between the United States east coast and Bermuda within the next 72 hours. See area of interest #16 section below for more information.
(3) Cold core upper vorticity that has been suppressing tropical activity in the Caribbean over the last several days is expected to finally weaken over the next few days while remaining cut-off from high-latitude cold air. This is expected to allow for the expansion of tropical upper ridging with lower shear and increased upper outflow. This more favorable upper air pattern may allow the large central Atlantic tropical wave...formerly designated area of interest #14 on this blog... to be re-invigorated as the wave eventually moves into the western Caribbean...Yucatan peninsula... and Bay of Campeche. This region may require monitoring for tropical development in approximately one week from today.
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 are designated #15 and #16 as I designated the other fourteen of this year in previous birdseye view posts on the home page. 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.
AREA OF INTEREST #15...The tropical low pressure area in the northern Gulf of Mexico has become increasingly elongated east-west over the last 24 hours. In the mid-levels of the atmosphere this is seen by observing changes in the CIMSS 850 mb vorticity product (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). At the surface the NHC TAFB has added an east-west trough of low pressure to their analysis. The elongation of the low pressure area is probably attributed to the sprawling outflow zone of the upper ridge that spans the central United States and northern Gulf... which is allowing for surface pressures to fall in a large area instead of a more focused area.
Satellite animation has shown the maximum spin of this disturbance has become established toward the west side of the elongated system... located near 27.5N-94W as of 1200Z earlier this morning. This clearly requires a westward adjustment to my forecast track for this disturbance... with the disturbance now clearly en route to southern Texas instead of Louisiana. Also helping the westward shift of the forecast track is the location of the maximum spin away from the narrow surface ridge weakness between the Atlantic and Great Lakes surface ridges (the narrow ridge weakness signals the location of the slow-moving surface front that has been over the southeastern United States). This reduces the steering influence of the narrow ridge weakness and hence greatly increases the westward push of the Great Lakes surface ridge. Even though the Great Lakes ridge will soon be weakened by the frontal low advancing east from Minnesota... another surface ridge is expected to expand along the United States Gulf coast to be supported by the western convergence zone of a chunk of upper vorticity to dive south from the current central/northern Canada upper trough. This additional surface ridge should push this disturbance further west inland into southern Texas after it makes landfall on the Texas coast in 24 hours. Although low odds of tropical cyclone formation are warranted due to the short remaining amount of time this disturbance will be over water... I do have odds above the NHC's current 10% as the thunderstorm activity of this disturbance has continually increased over the last few hours (after it waned last night). Regardless of tropical cyclone formation or not... this system has the potential to bring heavy rainfall with flash flooding potential to southern Texas later this weekend.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Aug 14)...20% chance of tropical cyclone formation (Vicinity of Matagorda Bay Texas near 28N-96.2W)
IOH 48 Hr Outlook (1200Z Aug 15)...0% chance of tropical cyclone formation (southern Texas near 28N-99W)
AREA OF INTEREST #16...A large upper trough and surface frontal system has recently entered the western Atlantic from eastern North America. Models have increasingly agreed that the sprawling central US upper ridge will help cut-off a portion of this upper trough into cut-off upper vorticity just offshore of the southeastern United States. In order for a focused area of subtropical or tropical low pressure to form... the upper vorticity will have to be amplified in nature in order to establish a local maximum of upper divergence/low shear on its east side. The ECMWF model has recently joined the CMC in suggesting this... and therefore I have initiated an associated area of interest. This marks the sixteenth tropical area of interest for the Atlantic basin I am tracking this year. Note the GFS also sugegsts some cut-off upper vorticity... however it is not as amplified as the ECMWF and CMC. Due to the disagreement in the amplitude of the upper vorticity... I only assign low 10% odds of tropical cyclone formation.
Any disturbance that develops offshore of the southeastern United States is expected to shift northeast toward the surface ridge weakness associated with the remainder of the current western Atlantic surface front. In the latter part of the forecast period... the northeast track of the disturbance would continue in the flow out ahead of the frontal low currently approaching from Minnesota. By 72+ hours... any disturbance that develops will either itself transition into a large non-tropical frontal low in the northwest Atlantic supported by the approaching central/northern Canada upper trough... or become absorbed by a seperate northwestern Atlantic non-tropical frontal low to be induced by this upper trough. This will bring an end to potential subtropical/tropical development.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Aug 14)...0% chance of tropical cyclone formation (offshore of the southeastern United States near 30N-78.5W)
IOH 48 Hr Outlook (1200Z Aug 15)...10% chance of tropical cyclone formation (offshore of the southeastern United States near 32.5N-75W)
IOH 72 Hr Outlook (1200Z Aug 16)...0% chance of tropical cyclone formation (western Atlantic near 34N-70W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
0000Z (Aug 13) CMC Model Run...
**For area of interest #15...no development shown
**For area of interest #16...Surface low develops offshore of South Carolina near 31.5N-78.5W at 24 hours... by 78 hours transitions into a large non-tropical frontal low accelerating northeastward into the northwestern Atlantic.
0000Z (Aug 13) ECMWF Model Run...
**For area of interest #15...no development shown
**For area of interest #16...Surface low develops offshore of Georgia and South Carolina near 31.2N-78.5W at 24 hours and remains generally staionary through 48 hours... by 72+ hours transitions into an elongated and large non-tropical frontal low accelerating northeastward into the northwestern Atlantic.
0600Z (Aug 13) GFS Model Run...
**For area of interest #15...no development shown
**For area of interest #16...no development shown
0000Z (Aug 13) NAVGEM Model Run...
**For area of interest #15...no development shown
**For area of interest #16...no development shown