MY 2024 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #52

*******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 JULY 26 2024 3:44 PM EDT...

After a long pause... the Atlantic tropics are waking up as two areas of interest for tropical development have emerged:

(1) See area of interest #13 section below for information on possible northwest Atlantic tropical cyclone formation in the days ahead... offshore of the northeastern United States and Nova Scotia. This area of interest is currently not in the NHC tropical weather outlook.

(2) See area of interest #14 section below for a new area of interest in the tropical belt of the Atlantic (between Africa and the Lesser Antilles) declared as of 2 PM EDT by the National Hurricane Center.

AREA OF INTEREST #13... The surface front currently over the east-central United States is forecast to be pulled into offshore western Atlantic waters by the current east Canada frontal low. Models are coming into better agreement that a portion of the front's upper trough will evolve into a circular enough upper vortex with a focused instead of elongated eastern upper divergence zone which would promote the formation of a well-defined surface low pressure center along the front while the front is over warm waters... therefore declaring an area of interest for possible western Atlantic tropical development in the days ahead. This marks the thirteenth area of interest tracked on this site this year.

The upper trough associated with the lengthy surface front currently has a southwest-northeast tilt across eastern North America ahead of a hot air mass upper ridge moving into central North America. The upper ridge will soon break the tail half of the upper trough into a piece of energy over the south-central US and upper vortex positioned near the United States east coast... with the remainder of the upper trough continuing east across the higher latitudes of the Atlantic. The upper vortex and associated well-defined surface low pressure center that develops along the surface front materializes in about 48 hours which is why I assign only a low 10% chance of tropical cyclone formation around that time. In the later part of the forecast period the surface low whirls toward the core of the parent upper vortex with the two moving in tandem as typically seen with a post-mature non-tropical system... and honestly if this system has tropical characteristics at that point it would resemble more of a hybrid subtropical system. For the later part of the forecast... the current upper trough moving into western North America merges with a polar upper vortex from north-central Canada... resulting in an amplified upper trough over eastern Canada by 72 hours which the models currently agree that the upper vortex and surface low will drift northwards toward. By 96 hours the northward motion of the upper vortex and surface low continues as the aforementioned south-central US energy merges with the remainder tail portion of the western North America upper trough... resulting in a combined upper trough over central North America that continues pulling the upper vortex northbound. My peak odds of tropical cyclone formation are at a low 20% as this system will only have a short time over warm enough waters (26+ deg C) to acquire tropical characteristics... with odds of 0% after 72 hours due to cooler waters. A couple of final notes regarding the forecast track... (1) in the current suite of model runs the eastern Canada upper trough at 72 hours is barely close enough to pull the upper vortex/surface low northbound... therefore it is possible that only a slight change in future model runs would result in little to no net northward motion in the 48 to 72 hour period which would give this system more time over warmer waters... if this occurs would be raising odds of tropical cyclone in future updates... (2) models are still in disagreement with the forecast position of the upper vortex and resultant position of the forecast surface low of interest... with the recent 0600Z GFS being more east and 0000Z ECMWF being more west... my forecast track splits the difference and is similar to the 0000Z CMC which was also in the middle of the GFS/ECMWF split.

Impacts to land areas will likely be limited to possible coastal surf for the northeastern United States... New Brunswick... and Nova Scotia in the Sunday to Monday window when this system is at its peak intensity offshore. This is due to the fact the surface low will likely be rapidly weakening while moving northward into land areas while having whirled beneath the core of the upper vortex where supportive upper divergence will be lacking (i.e. no non-tropical support mechanism)... combined with the cooler waters providing no tropical support mechanism.

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

IOH 24 Hr Outlook (1200Z Jul 27)... 0% chance of tropical cyclone formation (vicinity of Cape Hatteras North Carolina near 35N-75.5W)

IOH 48 Hr Outlook (1200Z Jul 28)... 10% chance of tropical cyclone formation (western Atlantic offshore of the eastern US near 36N-70.5W)

IOH 60 Hr Outlook (0000Z Jul 29)... 20% chance of tropical cyclone formation (western Atlantic offshore of the eastern US near 38N-70.5W)

IOH 72 Hr Outlook (1200Z Jul 29)... 10% chance of tropical cyclone formation (south of Cape Cod Massachusetts near 40N-70.5W)

IOH 96 Hr Outlook (1200Z Jul 30)... 0% chance of tropical cyclone formation (inland over southern part of Maine/New Hampshire border near 43.5N-71W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 2 PM EDT**************************

Not in the official outlook

AREA OF INTEREST #14... As of 2 PM EDT the NHC has spotted a new area of interest for possible tropical development... within the tropical belt of the Atlantic between Africa and the Lesser Antilles... this will mark the fourteenth tropical Atlantic area of interest tracked on this site this year. Per the NHC tropical weather outlook this new area of interest consists of a spin near 10N-44W confirmable with the CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) and trailing broad tropical wave of low pressure analyzed by the NHC TAFB to be along 32W longitude. Noting that the broad wave emerged from Africa around July 22 and 23 while its southwest side was noted to produce a distinct and persistent thunderstorm burst ahead of the wave axis (on the 23rd the thunderstorm burst was located near 10N-27.5W as noted in earlier post #49... https://www.infohurricanes.com/post/my-2024-atlantic-hurricane-season-birdseye-view-post-49). It is likely the leading spin currently toward 44W longitude originated from this thunderstorm burst... with the broad wave currently at 32W and leading spin producing an east-west elongated area of thunderstorms to the south of the ongoing dry Saharan air outbreak.

Today's early CMC and ECMWF models suggest the leading spin and broad wave merge with time while moving west-northwest across the tropical belt of the Atlantic and then eventually the Caribbean region while steered by the Atlantic surface ridge... with the combined system staying an amplified surface wave over the next week which indicates a vigorous disturance but not necessarily tropical cyclone formation... however this is apparently enough of a signal in the models for the NHC to declare an area of interest. In the short-term atmospheric parameters seem to favor this area of interest as it heads into a break in the dry Saharan air in the short-term... between a large patch offshore of Mauritania and another large patch in the eastern Caribbean. In the upper-levels... the short-term upper wind outlook indicates this system will remain under an anticyclonic wave of upper outflow between an inverted upper trough to the east and the current cut-off upper vorticity to the northwest (the inverted upper trough develops within the south side of the regional tropical upper ridge... as the east side of the upper ridge weakens due to the approach of current northeastern Atlantic and southern Spain upper vorticity while the upper vorticity is shoved south by the currently amplifying north Atlantic upper ridge). The longer-term upper wind outlook is uncertain... on the one hand the inverted upper trough to the east and cut-off upper vorticity to the northwest could weaken to keep favorable anticyclonic outflow in progress over the disturbance. On the other hand the inverted upper trough could catch this system from the east and/or the cut-off upper vorticity does not weaken fast enough... which could create episodes of shear and/or upper outflow suppression. For the short-term I agree with the NHC on 0% odds of tropical cyclone formation as the two initial surface features need time to merge into one disturbance... however for the longer term I have very low 10% odds of tropical cyclone formation at this time due to the uncertainty in the longer-term upper wind outlook. Regardless of tropical cyclone formation or not... this disturbance could bring heavy rainfall to the Lesser Antilles by the middle of this upcoming week.

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

IOH 24 Hr Outlook (1200Z Jul 27)... 0% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-38W)

IOH 48 Hr Outlook (1200Z Jul 28)... 0% chance of tropical cyclone formation (central tropical Atlantic near 11.5N-45W)

IOH 72 Hr Outlook (1200Z Jul 29)... 10% chance of tropical cyclone formation (central tropical Atlantic near 12N-50W)

IOH 96 Hr Outlook (1200Z Jul 30)... 10% chance of tropical cyclone formation (east of the southern Lesser Antilles near 12.5N-55W)

IOH 120 Hr Outlook (1200Z Jul 31)... 10% chance of tropical cyclone formation (southern Lesser Antilles near 13N-60.5W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 2 PM EDT**************************

Formation chance through 48 hours... 0%

Formation chance through 7 days... 20%

...COMPUTER MODEL SUMMARY...

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

0000Z (Jul 26) CMC Model Run...

**For area of interest #13... surface front currently over east-central US moves offshore in next 42 hours... through 66 hours a frontal cyclone with possible tropical characteristics develops southeast of Massachusetts near 38N-68.5W under the supportive eastern divergence zone of parent upper vortex... combination of lack of upper divergence beneath core of upper vortex (lack of non-tropical support) and cooler waters (lack of tropical support) causes the surface low/cyclone to weaken while passing just east of Cape Cod Massachusetts through 90 hours... the dissipating surface low then continues north into Maine through 108 hours

**For area of interest #14... no development shown

0000Z (Jul 26) ECMWF Model Run...

**For area of interest #13... surface front currently over east-central US moves offshore in next 36 hours... through 48 hours SW/NE elongated frontal low develops with best-defined center at NE end of the circulation near 36N-70W... through 84 hours the frontal low intensifies into a more circular cyclone with possible tropical characteristics positioned just south of Long Island New York and under the supportive eastern divergence zone of parent upper vortex... through 96 hours the small cyclone begins to quickly weaken while whirling northwestward into the core of the parent upper vortex (where upper divergence is lacking) and dissipates over New York City

**For area of interest #14... no development shown

0600Z (Jul 26) GFS Model Run...

**For area of interest #13... surface front currently over east-central US moves offshore in next 42 hours... through 63 hours a frontal cyclone with possible tropical characteristics develops east-southeast of Massachusetts near 38.5N-66W... combination of lack of upper divergence beneath core of upper vortex (lack of non-tropical support) and cooler waters (lack of tropical support) causes the surface low/cyclone to weaken while moving into the waters offshore of Maine through 84 hours... surface low dissipates just offshore of Maine/Canada border at 93 hours

**For area of interest #14... no development shown

0600Z (Jul 26) NAVGEM Model Run...

**Model run not available at above-mentioned source