BIRDSEYE VIEW POSTS

Since 2012 on the Weather Underground (www.wunderground.com) blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments via Disqus on Weather Underground at www.wunderground.com/cat6. You can see my Disqus feed at this link for my latest comments. Feel free to reply to me with your disqus account or e-mail at IOHurricanes@outlook.com 

 
 
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MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #23

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


...FRIDAY JUNE 5 2020 2:17 PM EDT...


Tropical Depression Cristobal accelerates northward into the Gulf of Mexico from the Yucatan peninsula while becoming better organized and poised to strengthen while approaching the United States Gulf coast this weekend...see Cristobal section below for details.


Elsewhere...computer models are in increasing agreement that a surface low pressure area will develop in the central Atlantic to the east of Bermuda in about 5 days in response to current upper trough over central Canada diving southward and amplifying into a cut-off upper vortex in the Atlantic along the east side of the upper ridge emerging from western North America...as the upper ridge later amplifies in the eastern warm air advection zone of what is expected to be the remnant frontal cyclone of Cristobal moving into the Great Lakes region and possibly southeastern Canada. The cold temperatures of the forecast cut-off upper vortex may allow for subtropical development despite central Atlantic water temperatures in the low 20s of deg C...but I have not declared an area of interest at this time as this system is forecast to reach maturity just after the more confident 5-day window...and as computer models still vary in where Cristobal's remnant frontal cyclone stalls in its post-mature and decay phase (NAVGEM as far south as the Great Lakes...ECMWF as far north as Hudson Bay Canada). The evolution of Cristobal's remnant frontal cyclone will influence the exact evolution and track of the central Atlatnic low pressure system...with a further north solution for Cristobal's remmant allowing the upper ridge to settle further north and push the central Atlantic feature west-southwest toward the Bahamas...and a further south solution for Cristobal's remnant allowing the upper ridge to settle further south and block westward progress...only allowing for a slow westward drift toward Bermuda or adjacent waters.


TROPICAL DEPRESSION CRISTOBAL...Cristobal which has long plagued the southeastern Mexico and western Central America region with significant rainfall flooding is finally on an exit path from the region while its center accelerates northward over the western Yucatan peninsula. This is in response to the amplifying upper vorticity in the western Gulf of Mexico which is now helping to steer Cristobal while also transitioning Cristobal into a large low pressure area supported by the eastern divergence of the upper vorticity. This cold core upper vorticity has amplified due to the adjacent warm western north America upper ridge that has amplified in warm air advection from a surface southerly fetch on the east side of the broad western United States low pressure region induced by a pair of vigorous upper vorticity lobes south of Alaska and offshore of Mexico and California. The amplification of the upper vorticity may also be due to the tremendous latent heat release of the thunderstorm bursts that were occuring through last night over the Yucatan peninsula...which has helped re-enforce the upper ridge over Central America at a location just southeast of the upper vorticity. Some of the most recent satellite trends are a bit concerning as the north side of Cristobal's circulation is already filling in with thunderstorms and possibly warm core upper outflow...suggesting the latent heat release may be enough to fight off the negative effects of wind shear and dry air of the cold core upper vorticity (dry sinking air is being induced by the western convergence of the upper vorticity). Combined with the maturing banding features around Cristobal's center...I am raising my intensity forecast to a peak just below hurricane force. This now brings the possibility of Cristobal becoming a category 1 hurricane just before the center makes landfall in southeastern Louisiana...something I have not considered since birdseye view post #20 on Tuesday. Due to the current northward acceleration and current center fix being a tinge north-northwest of my previous forecast...I have also adjusted my forecast track points northwestward which now suggests landfall of the center in southeastern Louisiana in as soon as 48 hours.


After the forecast Louisiana landfall...I support the idea of a northwestward lean in track as the current upper trough energy over central Canada will dive south and amplify over the northeastern United States due to the highly amplified nature of the western North America longwave upper ridge. This will position the western convergence zone of the upper trough and resulting surface ridge to the northeast of Cristobal...close enough for the ridge to add a west component to the storm track. Also in the upper layers the steering supports a west component as the western North America longwave upper ridge will be shifting eastward to a position directly north of Cristobal. The eastward shift of the longwave ridge will be from the merger of the current vigorous energy south of Alaska and offshore of California as they become a vigorous upper trough sliding into the western United States...with the current western US broad surface low pressure area supported by the eastern divergence zone of these pieces of energy likewise shifting eastward and driving warm air advection into the cold core western Gulf upper vorticity. This should cause the upper vorticity to fade around Cristobal's landfall time...the absence of the vortcity making it easier for Cristobal to also lean west post-landfall. Just after 96 hours...computer models increasingly suggest that the remants of Cristobal could align with the eastern upper divergence maximum of the forecast strong western US upper trough...resulting in the remnant circulation intensifying into an intense frontal cyclone that moves through the Great Lakes and possibly into eastern Canada. Therefore wind impact to the Great Lakes region looks increasingly likely in about 5 days.


Interests on the United States Gulf coast from Louisiana to the Florida panhandle should now begin making preparations for coastal storm surge and wind impact from what appears to be higher chances of a strong tropical storm...possibly a category 1 hurricane...coming ashore in as soon as 48 hours...see bulletins on home page of this site for details. The severe rainfall flood risk over southeastern Mexico and western Central America appears to be ending as Cristobal lifts northward and away.

******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********

0 Hr Position (1200Z Jun 5)...35 mph maximum sustained wind tropical depression centered over the western Yucatan peninsula at 20N-89.9W

IOH 24 Hr Forecast (1200Z Jun 6)...50 mph maximum sustained wind tropical storm centered in the Gulf of Mexico at 25N-89.9W

IOH 48 Hr Forecast (1200Z Jun 7)...70 mph maximum sustained wind tropical storm making landfall on the southeast Louisiana coast at 29N-90W

IOH 72 Hr Forecast (1200Z Jun 8)...35 mph maximum sustained wind tropical depression centered over northeastern Louisiana at 32N-92W

IOH 96 Hr Forecast (1200Z Jun 9)...Remnant frontal low pressure centered over northeastern Missouri at 38N-91W


...COMPUTER MODEL SUMMARY...

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


0000Z CMC Model Run...For Tropical Depression Cristobal...by 36 hours has broad center of circulation located in the Gulf of Mexico just northwest of the Yucatan peninsula...forecasts landfall over southeastern Louisiana at 78 hours...has Cristobal losing identity over northern Arkansas to larger frontal cyclone to the west by 120 hours. Elsewhere...develops central Atlantic broad surface low at 31.5N-54.5W at 108 hours in response to current central Canada upper trough diving south and amplifying into the Atlantic...has surface low become better defined and consolidated by 132 hours and then dissipates it just east of Bermuda in the long range.


0000Z ECMWF Model Run...For Tropical Depression Cristobal...has center of circulation enter Gulf of Mexico from northwestern corner of Yucatan peninsula at 24 hours...has landfall over southeastern Louisiana just after 72 hours. Has tropical cyclone shift northward across the Gulf of Mexico and reach southeast Lousiana coast at 96 hours (suggests possibly strong tropical cyclone from 72 to 96 hours)...accelerates remnants of Cristobal into Missouri/Illinois border at 120 hours...positioning the remnants to become the dominant intensifying frontal cyclone in the region which just after 120 hours rapidly accelerates across western Great Lakes region and into southeastern Canada. Elsewhere...develops central Atlantic broad surface low pressure area east of Bermuda at 96 to 120 hours in response to current central Canada upper trough diving south and amplifying into the Atlantic...shifting west-southwest toward Bahamas Florida east coast in the long range...no consolidated circulation shown in broad surface low pressure area.

0600Z GFS Model Run...For Tropical Depression Cristobal...has broad center of circulation emerge into Gulf of Mexico from north-central Yucatan peninsula coast in 12 to 18 hours...forecasts landfall over southeastern Louisiana at 60 hours...has remnant circulation of Cristobal crossing western Great Lakes region and entering eastern Canada as a large intensifying frontal cyclone. Elsewhere...develops central Atlantic broad surface low at 31N-57.5W at 102 hours in response to current central Canada upper trough diving south and amplifying into the Atlantic...has surface low become better defined and consolidated further north by 114 to 120 hours at 36N-60W...has this circulation drift west and pass north of Bermuda in the longer range.


0600Z NAVGEM Model Run...For Tropical Depression Cristobal...has broad center of circulation emerge into Gulf of Mexico from northwestern corner of Yucatan peninsula in 18 hours...forecasts landfall over southeastern Louisiana at 72 hours...accelerates remnants of Cristobal into Missouri/Illinois/Kentucky border at 120 hours...positioning the remnants to become the dominant intensifying frontal cyclone in the region which in the long range stalls over the Great Lakes region and weakens in its mature and post-mature phase. Elsewhere...develops central Atlantic broad surface low at 30.5N-60.5W at 102 hours in response to current central Canada upper trough diving south and amplifying into the Atlantic...in the long range has this feature drift westward into Bermuda.

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