MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #42
*******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.**********
...WEDNESDAY JUNE 24 2020 11:59 PM EDT...
See Dolly section below for final statement on this cyclone as it has lost its tropical characteristics and is about to dissipate soon. Elsewhere...the complex disturbance that spanned the northwest Gulf of Mexico to eastern Texas has consolidated into a frontal low pressure located inland over southeast Texas. The eastern lobe of this frontal low...or possibly a second sepereate frontal low...will be crossing the northwestern Atlantic warm Gulf stream waters on a path similar to what Tropical Storm Dolly took by 48 to 96 hours according to the suite of computer model runs in the model summary below...while supported by a shortwave upper trough to eject from the longwave upper trough currently over eastern North America. Because the shortwave upper trough is not expected to stall as a cut-off upper vortex...this system is not likely to acquire tropical characteristics like Dolly did.
Another shortwave upper trough and surface frontal system currently moving into the western United States will enter the western Atlantic by next week. The upper ridge out ahead of this front...currently spanning the western United States and eastern Pacific waters offshore of Baja California...will be dominating the western Atlantic with low shear and upper outflow in the long term. Therefore it is possible a tropical cyclone forms along this front and below the supportive upper ridge at a location northwest or west-northwest of Bermuda as the ECMWF and CMC models are currently suggesting by 168 hours (7 days).
And finally in the western Gulf of Mexico...a surface trough of low pressure originating over southeastern Mexico...possibly a north fracture of one of the tropical waves that has recently entered the eastern Pacific...is shifting northward while steered by the west flank of the expansive Atlantic surface subtropical ridge. Upper-level winds have become more conducive for tropical development in this region as the upper vortex that was in the northwestern Gulf of Mexico has shifted westward and away into northern Mexico while pushed around the western United States upper ridge mentioned in the previous paragaraph...allowing for another upper ridge over the far eastern Pacific and western Gulf of Mexico to expand in its wake. The outflow of the upper ridge is allwoing the surface trough to produce thunderstorm activity...but the activity that was present earlier this past afternoon has broken up into smaller clusters perhaps as the dry saharan air dominating the eastern Gulf of Mexico has affected this disturbance. Furthermore computer models are not developing this disturbance...so will not be considering it an area of interest for tropical development at this time.
REMNANTS OF DOLLY...Tropical Storm Dolly in the northwest Atlantic and its parent upper vortex have continued moving northeastward around the west side of deep-layered ridging off to the east (central Atlantic upper ridge which has aligned with the north lobe of the Atlantic surface subtropical ridge). This track has moved Dolly into much cooler waters such that it is now a remnant swirl of low pressure without thunderstorms. And with Dolly's remnant still beneath the upper vortex where there is a lack of divergence to support it...expect the remnant to soon dissipate as it nears the southeastern Canadian coasts of Nova Scotia and Newfoundland. This is my final statement on Dolly on this blog.
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z CMC Model Run...Frontal low consolidates near 36.5N-71W by 42 hours...se of Newfoundland by 90 hours. Next front swings into west Atlantic by 120 hours...triggering possible tropical cyclone formation northwest of Bermuda near 35N-67.5W by 168 hours
1200Z ECMWF Model Run...Frontal low consolidates near 36N-70W by 48 hours...east of Newfoundland by 96 hours. Next front swings into west Atlantic by 96 hours...triggering possible tropical cyclone formation near 35N-70W by 168 hours.
1800Z GFS Model Run...Weak frontal low near 37.5N-71W by 42 hours...south of Newfoundland by 102 hours. Next front becomes draped across northwest Atlantic by 168 hours.
1200Z NAVGEM Model Run...Frontal low consolidates near 39N-65W by 54 hours...strengthens notably while reaching southeast coast of Newfoundland by 78 hours. Next front swings into west Atlantic by 114 hours...low pressure along this front near 38N-65W by 132 hours.