*******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.*********
...UPDATE...FRIDAY AUGUST 9 2024 1:40 PM EDT...
The birdseye view chart has been updated below to include the surface and upper air charts... the update was released very early this morning without those charts to allow the update to be released in a more timely manner.
...FRIDAY AUGUST 9 2024 1:45 AM EDT...
See remnants of Debby section below on the former tropical storm that continues to bring impacts across the eastern United States as a remnant non-tropical frontal low. See areas of interest #16 and #17 sections below for more information on a pair of tropical waves of low pressure being monitored for possible development in the days ahead... area of interest #16 may bring heavy rain and gusty winds to Veracruz and vicinity this weekend... area of interest #17 may impact the northeastern Caribbean Islands as a tropical cyclone just after this weekend.
REMNANTS OF DEBBY... Tropical Storm Debby has continued north-northwest across inland areas of the Carolinas... and as of this evening it has already completed transition into a non-tropical frontal low centered over western North Carolina while merging with the surface cold front that was initially brought into the region by the former Ohio Valley frontal low that was to the northwest. As such this will be my final statement on Debby on this blog as it is no longer a tropical system. Soon the remnant frontal low will accelerate north-northeast across the inland regions of the northeastern United States while channeled into the flow ahead of the approaching Great Lakes/eastern Canada frontal low and associated upper trough... and may re-strengthen a bit while exposed to the supportive eastern divergence zone of the upper trough. By 48 hours ex-Debby is then expected to lose its identity while in the vicinity of southeastern Quebec or New Brunswick to the aforementioned frontal low incoming from the west or to another frontal low/upper vortex system slated to dive southeast in the waters between northeast Canada and western Greenland.
Based on the current radar presentation of ex-Debby as of this writing... a corridor of heavy rainfall with flash flood potential is expected across Virginia and West Virginia... Maryland... Pennsylvania... Delaware... New Jersey... New York... Connecticut... Rhode Island... Massachusetts... Vermont... New Hampshire... Maine... New Brunswick... and southeastern Quebec. Gusty winds and coastal surf could develop across this region should ex-Debby regain some strength as discussed above. The following are the strongest winds (in mph) at each of the following National Weather Service station (weather.gov) recorded so far:
**Florence (inland NE SC)… sustained 24… gust 38… 10:53 PM EDT August 7
**Georgetown (coastal NE SC)… sustained 12… gust 31… 12:15 PM EDT August 8
**Myrtle Beach (coastal NE SC)… sustained 26… gust 38… 5:56 AM EDT August 8
**Wilmington (coastal SE NC)… sustained 28… gust 43… 4:53 PM EDT August 8
**Morehead City (coastal SE NC)… sustained 25… gust 40… 5:58 AM EDT August 8
**Jacksonville (inland SE NC)… sustained 21… gust 44… 9:56 AM EDT August 8
**Fayetteville (inland SE NC)… sustained 26… gust 43… 10:49 PM EDT August 8
**Raleigh (inland central NC)… sustained 20… gust 37… 4:51 AM EDT August 8
**Greenville (inland east-central NC)… sustained 20… gust 30… 11:50 AM EDT August 8
**Charlotte (inland southwestern NC)... sustained 22... gust 47... 4:52 AM EDT August 8
**Greensboro (inland north-central NC)... sustained 28... gust 47... 8:54 AM EDT August 8
**Hatteras (coastal eastern NC)... sustained 20... gust 40... 6:51 PM EDT August 8
**Elizabeth City (northeastern NC)... sustained 23... gust 37... 2:54 PM EDT August 8
**Virginia Beach (southeastern VA)... sustained 22... gust 36... 10:56 PM EDT August 8
**Danville (south-central VA)... sustained 20... gust 37... 10:53 AM EDT August 8
**Lynchburg (western VA)... sustained 18... gust 36... 3:54 PM EDT August 8
**Richmond (central VA)... sustained 20... gust 33... 9:54 PM EDT August 8
AREA OF INTEREST #16... The tropical wave of low pressure that was previously crossing the Caribbean has spent much of the last 24 hours crossing western Central America. Curiously as of 0000Z the NHC TAFB re-analyzed that the surface wave axis was notably further west toward the Guatemala/southeastern Mexico border region... however satellite imagery and the CIMSS 850 mb vorticity product show a mid-level rotation is in progress further east over Honduras. Even while initializing this system over Honduras... this is still west of my previous forecast track and so my updated one is adjusted accordingly. This system is still expected to move west-northwest across the Bay of Campeche and toward Veracruz due to a combination of this system initially feeling the surface ridge weakness of ex-Debby... followed by this system rounding the southwest side of the North America surface ridge expected to build behind ex-Debby. By day 3 a northward turn across east-central and northeastern Mexico is shown as this system finishes rounding the North America ridge. The updated forecast track brings this system into the Bay of Campeche sooner... and before the current southeastern US suppressing upper vorticity drifts south toward the Bay of Campeche under the influence of the ongoing southwestern US upper ridge. Therefore I assess this system has a small chance of tropical cyclone formation before it moves into Veracruz. Based on the satellite apperance of this system as of this writing... it appears it will likely bring only scattered thunderstorms across western Central America and southeastern Mexico before it moves into the Bay of Campeche. Interests in east-central Mexico (Veracruz and vicinity) should be aware that this system could still bring heavy rain and gusty winds by this weekend should it attempt to develop in the Bay of Campeche.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Aug 10)… 0% chance of tropical cyclone formation (southeastern Bay of Campeche coast of Mexico near 19.2N-91W)
IOH 48 Hr Outlook (0000Z Aug 11)… 10% chance of tropical cyclone formation (western Bay of Campeche near 20N-95W)
IOH 72 Hr Outlook (0000Z Aug 12)… 0% chance of tropical cyclone formation (inland northeastern Mexico near 24.5N-98.5W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT**************************
Not in the official outlook
AREA OF INTEREST #17... Continuing to monitor the current eastern Atlantic tropical wave of low pressure for signs of development in the days ahead as it moves west-northwest toward the direction of the northeastern Caribbean Islands. As of this writing the tropical wave appears to be gaining a northwest-southeast tilt... with the northwestern circulation inactive while wrapped in dry Saharan air and the southeastern circulation becoming more interesting while showing early signs of developing curved thunderstorm bands in the vicinity of 11N-35W reminiscint of a developing tropical low. As such my updated forecast track is initialized using the southeastern circulation center... and for the next 24 hours the updated forecast track is adjusted north of the previous while having the southeastern center pulled by the northwestern circulation. A more west and less north track is shown for the 24 to 72 hour segment while then bumping into the south side of the Atlantic surface ridge... followed by an increase in the track north angle from 72 to 120 hours as this system rounds the southwest side of the Atlantic surface ridge. An increase in the north angle may also be helped by day 5 as the current central Canada upper trough wades offshore into the western Atlatnic and potentially erodes the west side of the steering Atlantic surface ridge... with the upper trough also potentially kicking cut-off upper vorticity southeastward toward this area of interest (should this area of interest indeed be a stronger/tall tropical cyclone by day 5... the cut-off upper vorticity may help bend the track north... more on the cut-off upper vorticity evolution in the next paragraph).
Upper winds over the tropical wave are forecast to become more conducive for development with time as follows… (1) a northwest Atlantic warm core upper ridge materializes in the warm sector of ex-Debby and the frontal low that will be approaching the Atlantic from the Great Lakes/eastern Canada region of North America… (2) the northwest Atlantic upper ridge pushes the cut-off upper vorticity currently northwest of the wave towards the west and away faster than the tropical wave’s forward heading… with the cool core upper vorticity also weakening with time due to prolonged isolation from high-latitude cold air… (3) the regional tropical upper ridge featuring low shear and outflow expands over this tropical wave in the wake of the retreating upper vorticity. Compared to my previous outlook... I have raised odds of tropical cyclone formation and now have peak odds above 50% for the 5-day window as most models agree on eventually developing the wave and the wave has become a little better organized with the aforementioned southeastern circulation center taking shape. However my peak odds are reserved toward day 5 rather than sooner as this system may struggle to develop in the short-term due to potential ingestion of dry Saharan air... and we may have to wait for this wave to be toward the northeastern Caribbean Islands (where concentrations of dry Saharan air tend to be less) for tropical cyclone formation. Interests in the northern Lesser Antilles... Virgin Islands...and Puerto Rico should be monitoring the progress of this tropical wave as tropical cyclone impacts from this system are possible just after this weekend.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Aug 10)... 0% chance of tropical cyclone formation (central tropical Atlantic near 12N-39.5W)
IOH 48 Hr Outlook (0000Z Aug 11)... 10% chance of tropical cyclone formation (central tropical Atlantic near 12.5N-44.5W)
IOH 72 Hr Outlook (0000Z Aug 12)... 25% chance of tropical cyclone formation (central tropical Atlantic near 13N-49W)
IOH 96 Hr Outlook (0000Z Aug 13)... 40% chance of tropical cyclone formation (east of the Lesser Antilles near 14N-54W)
IOH 120 Hr Outlook (0000Z Aug 14)... 60% chance of tropical cyclone formation (just east of the northern Lesser Antilles near 15.5N-59W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT**************************
Formation chance through 48 hours... 0%
Formation chance through 7 days... 50%
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
1200Z (Aug 8) CMC Model Run...
**For area of interest #16... organizes into a tropical low offshore of Belize at 24 hours which emerges into the eastern Bay of Campeche from the southwestern part of the Yucatan peninsula by 48 hours... while approaching the Tamaulipas/Veracruz border region through 84 hours weakens to a trough with no development shown thereafter
**For area of interest #17... organizes into a tropical low near 14N-35W at 66 hours with tropical cyclone formation suggested near 14.5N-42.5W at 96 hours... begins to approach the northern Lesser Antilles by 168 hours as a potentially intense tropical cyclone
**Vigorous tropical wave emerges from western Africa at 36 hours and crosses the Republic of Cabo Verde Islands at 102 hours as a broad tropical low... broad tropical low opens back to a wave west of the Cabo Verde Islands at 144+ hours with no development shown thereafter.
1200Z (Aug 8) ECMWF Model Run...
**For area of interest #16... no development shown
**For area of interest #17... organizes into a tropical low centered just south of Puerto Rico at 138 hours... tropical low center continues northwest into waters between Dominican Republic and Puerto Rico through 144 hours with tropical cyclone formation suggested thereafter as system curves north-northwest offshore of the Dominican Republic and the southeastern Bahamas through 168 hours.
**Vigorous tropical wave of low pressure emerges from west coast of Africa at 36 hours and passes over the Republic of Cabo Verde Islands at 78 hours as a broad tropical low... tropical low continues west to 15.5N-43W through 168 hours
**Additional vigorous tropical wave of low pressure emerges from western Africa around 168 hours
1800Z (Aug 8) GFS Model Run...
**For area of interest #16... no development shown
**For area of interest #17... organizes into a tropical low near 14N-43W at 63 hours... compact tropical cyclone formation suggested near 14.8N-49W at 81 hours... compact tropical cyclone moves into the northern Lesser Antilles at 123 hours then over the southern Virgin Islands at 135 hours... makes landfall across northeastern Puerto Rico by 141 hours which then curves increasingly north to pass just east of the southeastern Bahamas by 168 hours
1800Z (Aug 8) NAVGEM Model Run...
**For area of interest #16... no development shown
**For area of interest #17... no development shown
**Strong tropical wave emerges from western Africa at 36 hours and moves into the Republic of Cabo Verde Islands by 84 hours as a broad tropical low... tropical low drifts southwest very slowly away from the Cabo Verde Islands through 168 hours
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