*******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.**********
...MONDAY OCTOBER 10 2022 2:59 AM EDT...
Julia has survived its passage across Nicaragua to live on as an eastern Pacific tropical storm. The tropical storm has potential to spread impacts across western Central America and southeastern Mexico over the next couple of days... see Julia section below for more information. Elsewhere... continuing to watch for the potential formation of a central Atlantic subtropical or tropical disturbance this week. See area of interest #38 section below for more information.
TROPICAL STORM JULIA... After making landfall early on Sunday with 85 mph maximum sustained winds... Hurricane Julia proceeded to weaken to an inland tropical storm over Nicaragua. Per the NHC... the tropical storm proceeded to make a westward run over the less rugged terrain of southern Nicaragua such that Julia's center has successfully made it into the eastern Pacific waters on the other side of Nicaragua without weakening to a tropical depression. However Julia is barely a tropical storm while featuring 40 mph maximum sustained winds. Per the latest naming conventions... Julia's survival while moving into the eastern Pacific allows it to keep its Atlantic name... and I am also continuing to forecast Julia on this blog as a result. The disruption caused by the land interaction has made Julia a peculiarly large and broad system for a tropical cyclone which as of this writing features a central area of disorganized thunderstorms over El Salvador... southwestern Honduras... and offshore eastern Pacific waters and an outer northern curved band of thunderstorms stretching from northeastern Nicaragua and eastern Honduras to northern Belize... southern Quintana Roo... and Campeche.
The models have multiple ways of handling the large circulation of Julia going forward. Within the computer model summary provided below... the GFS wants to develop a broad low pressure area just southwest of Julia that becomes a separate eastern Pacific tropical cyclone while Julia itself becomes absorbed into the new feature. The ECMWF and NAVGEM suggest that Julia reforms to the southwest then continues on a distinct feature offshore of southern Mexico over the next few days. The CMC comes the closest to entangling Julia into the surface ridge weakness to be associated with a sprawling frontal cyclone that will soon form over North America with the support of an amplified upper trough that moves into western Canada. The idea of a southwestern circulation or southwestward reformation could be due to Julia still being in an environment of northeasterly shear on the south side of the tropical upper ridge axis in the region... which would have a tendency to push the thunderstorms off to the southwest where the associated latent heat release driven upper-level high pressure and outflow would drive a new southwestern low pressure surface circulation. However with the latest satellite pictures showing Julia maintaining a central area of thunderstorms... it appears the light northeasterly shear really has not affected Julia since it entered the eastern Pacific and therefore I continue to forecast Julia curving west-northwest toward the aforementioned surface ridge weakness and into the Gulf of Tehuantepec and Oaxaca. My updated forecast track is nudged just slightly westward due to Julia's current position with respect to the prior forecast. My updated intensity forecast is raised just slightly and now explicitly shows Julia being a tropical storm up until landfall in Oaxaca... as Julia has successfully entered the eastern Pacific as a tropical storm instead of a tropical depression and is doing a good job so far of maintaining a central area of thunderstorms. Although it is theoretically possible that Julia could re-strengthen as the shear is light and waters are warm... the broad instead of focused circulation of Julia makes it difficult for this to happen and per the latest model runs and NHC official forecast Julia could lose its well-defined center and be downgraded to a remnant low. This is why I show no strengthening in the forecast below. After 72 hours... if the forecast below holds the remnants of Julia to be over Oaxaca and Veracruz could merge with the tail end of the cold front to be driven into the Bay of Campeche by the forecast sprawling North American frontal cyclone to become a Bay of Campeche tropical disturbance. In this scenario.. it is also not clear at this time if the NHC would consider the Bay of Campeche disturbance as Julia or a system of a different number/name... that will depend on if Julia can keep a distinct circulation throughout the process.
Regarding impacts to land areas:
(1) Gusty winds are likely occurring across coastal El Salvador... and over the next 48 hours shift westward across coastal Guatemala and the Gulf of Tehuantepec coast of Mexico should Julia maintain its tropical storm status... current center... and current heading.
(2) Julia is currently not producing a concentrated area of thunderstorms over land. However the circulation of the tropical storm is currently large and may fire off concentrated thunderstorm bursts across El Salvador... western Honduras... Guatemala... Belize... Quintana Roo... Yucatan... Campeche... Tabasco... Chiapas... Oaxaca... and eastern Veracruz over the next 48 hours. This could result in heavy rainfall with instances of flash flooding.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Oct 10)...40 mph maximum sustained wind tropical storm centered just offshore of the eastern El Salvador coast at 12.8N-88.1W
IOH 24 Hr Forecast (0000Z Oct 11)...40 mph maximum sustained wind tropical storm centered just offshore of southwestern Guatemala at 14.1N-92W
IOH 48 Hr Forecast (0000Z Oct 12)...40 mph maximum sustained wind tropical storm centered just offshore of the Oaxaca province of Mexico and in the western edge of the Gulf of Tehuantepec at 15.5N-95.5W
IOH 72 Hr Forecast (0000Z Oct 13)...Remnant trough over northwestern Oaxaca located near 17.5N-97W
AREA OF INTEREST #38... A broad surface trough of low pressure has developed in the open central Atlantic in the vicinity of 25N-50W as of this writing. This trough has formed with the support of the eastern divergence zone of an upper vortex in the region. To the west... the current pair of upper troughs over central and eastern Canada are expected to merge into an amplified western Atlantic upper trough... and the surface trough is expected to move west-northwest around the southwest side of the current Atlantic surface ridge and toward the surface ridge weakness to be generated by the eastern divergence zone of the forecast western Atlantic upper trough. By days 4 and 5... the surface trough has potential to mature into a subtropical or tropical disturbance that drifts east-northeast with the motion of the upper trough... while becoming supported by the eastern divergence zone of the upper trough. Because the upper trough will be amplified... wind shear levels could very well be low enough to support an organizing tropical or subtropical disturbance. However I assign low 10% odds of tropical cyclone formation during this timeframe due to the lack of computer model support showing development and as the eastern divergence zone of the upper trough will tend to be elongated instead of focused with a maximum... which could instead result in too broad of a system that struggles to consolidate into a surface cyclone feature.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Oct 11)...0% chance of tropical cyclone formation (central Atlantic near 27N-52W)
IOH 48 Hr Outlook (0000Z Oct 12)...0% chance of tropical cyclone formation (central Atlantic near 27.5N-54W)
IOH 72 Hr Outlook (0000Z Oct 13)...0% chance of tropical cyclone formation (central Atlantic near 27.5N-55W)
IOH 96 Hr Outlook (0000Z Oct 14)...10% chance of tropical cyclone formation (central Atlantic near 28.5N-53W)
IOH 120 Hr Outlook (0000Z Oct 15)...10% chance of tropical cyclone formation (central Atlantic near 29.5N-50.5W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Oct 9) CMC Model Run...
**For Tropical Storm Julia... loses identity just offshore of El Salvador at 24 hours within the east side of a larger broad tropical low pressure area developing just to the west.
**Surface trough extending north from Julia's dissipating circulation and northeastward from broad tropical low pressure area absorbing Julia becomes better defined over the Guatemala/Mexico border at 36 hours... surface trough organizes into a surface low in the western Bay of Campeche near 21N-95.5W at 78 hours... sprawling frontal cyclone over North America pushes cold front across the Gulf of Mexico which drags the surface low southeastward to 19.5N-95W through 120 hours.
**Tropical wave emerges from west coast of Africa at 72 hours... organizes into a tropical low near 11N-34W at 168 hours.
1200Z (Oct 9) ECMWF Model Run...
**For Tropical Storm Julia... weakens to a remnant low offshore of Guatemala at 24 hours... weakens further to a trough offshore of southwestern Mexico at 96 hours near 15N-104W
1800Z (Oct 9) GFS Model Run...
**For Tropical Storm Julia... weakens to a remnant low offshore of El Salvador at 12 hours... at this location loses identity at 18 hours within the east side of a larger broad tropical low pressure area developing just to the west (this broad tropical low forecast to develop into a tropical cyclone in the long range).
1800Z (Oct 9) NAVGEM Model Run...
**For Tropical Storm Julia... weakens to an east-west elongated remnant low offshore of El Salvador at 6 hours... remnant low becomes more circular with time and is located just offshore of southwestern Mexico near 18.8N-106W at 120 hours.