WxWatcher007

Worth noting that both the operational GFS and Euro have continued trending toward a direct Atlantic Canada impact in about 6-7 days. That leaves a lot of time for changes but the east trend a few days ago completely reversed.

First time we’ve been seeing run to run consistency on actual development. GFS has vorticity but never gets development going. It’s a complicated forecast, but I do think something is going to lift into the Gulf.

Still worth watching Franklin up there, though it looks like we may be settling on more Newfoundland impacts.

I’m not. I do think something’s going to lift into the Gulf though.

Need the Euro to follow the Canadian

Absolutely wild to record a wind gust that high

Central American Gyre. It’s a broad area of spin over the region that usually appears a few times a year but mostly late season. You can get homebrew spin ups from it in the Atlantic or EPAC but forecasting TC development from it is notoriously difficult. Even on the less bullish GFS, the broad vorticity is there. In the area right above the bottom arrow, you can see higher vorticity in the EPAC that’ll likely spin up. As a monsoon trough on the EPAC side (ribbon of higher vorticity) continues lifting north, it’ll bring more vorticity to the Atlantic. Whether something pops is anyone’s guess. It’s far more complicated than I just described. https://tropic.ssec.wisc.edu/real-time/atlantic/movies/wg8vor4/wg8vor4_loop.html In recent years some of our big dog storms in the Atlantic (Michael/Ida) have come from a CAG. Not saying that’ll happen here but a spin up in the western Atlantic and eastern Gulf would be primed since you have high end OHC and would probably need a low shear environment for even a seedling to organize.

Toss that, but I’ve been looking at potential from a CAG in that region for the last week of August going back a week now. A system in the eastern Gulf into the SE region wouldn’t surprise me. From there probably OTS but who knows. If we get anything this year, it’s not coming from a long track MDR wave IMO with the difficulty we’ve seen getting a proper WAR. It’s homebrew or bust around here.

Looks like some modest organization in between passes. Product: Air Force Vortex Message (URNT12 KNHC)Transmitted: 24th day of the month at 1:07ZAgency: United States Air ForceAircraft: Lockheed WC-130J Hercules with reg. number AF96-5300Storm Name: FranklinStorm Number & Year: 08 in 2023 (flight in the North Atlantic basin)Mission Number: 6Observation Number: 10 ( See all messages of this type for this mission. )A. Time of Center Fix: 24th day of the month at 0:40:10ZB. Center Fix Coordinates: 20.86N 70.54WB. Center Fix Location: 57 statute miles (92 km) to the SE (137°) from Cockburn Town, Turks and Caicos Islands (U.K.).C. Minimum Height at Standard Level: 1,461m (4,793ft) at 850mbD. Minimum Sea Level Pressure: 1003mb (29.62 inHg)E. Dropsonde Surface Wind at Center: From 200° at 9kts (From the SSW at 10mph)F. Eye Character: Not AvailableG. Eye Shape: Not AvailableH. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 32kts (36.8mph)I. Location & Time of the Estimated Maximum Surface Wind Inbound: 50 nautical miles (58 statute miles) to the SW (223°) of center fix at 0:25:30ZJ. Maximum Flight Level Wind Inbound: From 273° at 26kts (From the W at 29.9mph)K. Location & Time of the Maximum Flight Level Wind Inbound: 8 nautical miles to the SSW (205°) of center fix at 0:37:30ZL. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 40kts (46.0mph)M. Location & Time of the Estimated Maximum Surface Wind Outbound: 29 nautical miles (33 statute miles) to the NE (41°) of center fix at 0:49:30ZN. Maximum Flight Level Wind Outbound: From 129° at 41kts (From the SE at 47.2mph)O. Location & Time of the Maximum Flight Level Wind Outbound: 32 nautical miles (37 statute miles) to the NE (42°) of center fix at 0:50:30ZP. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,524m (5,000ft)Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 1,523m (4,997ft)R. Dewpoint Temp (collected at same location as temp inside eye): 7°C (45°F)R. Sea Surface Temp (collected at same location as temp inside eye): Not AvailableS. Fix Determined By: Penetration, Wind, Pressure and TemperatureS. Fix Levels (surface & flight level centers within 5nm of each other): Surface and 850mbT. Navigational Fix Accuracy: 0.02 nautical milesT. Meteorological Accuracy: 2 nautical milesRemarks Section: Maximum Flight Level Wind: 41kts (~ 47.2mph) which was observed 32 nautical miles (37 statute miles) to the NE (42°) from the flight level center at 0:50:30Z

Lemon (0/20) put on the western Caribbean by the NHC. Not a surprise, but there remains substantial inconsistency across guidance on the feature. Not often we get a CAG in August, but when they happen, big things can pop. The key to what happens in the next few days is getting vorticity to stay off the Yucatan, but even then with the trough expected to lift whatever's there north it may only delay some level of development.

I feel like we've seen a lot of this lately. I don't recall many storms in recent years being significantly disrupted by the mountainous terrain of Hispaniola. Now that the center is offshore, it's a short flight for recon as they head toward the storm.

12z guidance also moved back toward more direct impacts in Atlantic Canada.

Landfall Tropical Storm Franklin Discussion Number 12 NWS National Hurricane Center Miami FL AL082023 1100 AM EDT Wed Aug 23 2023 Franklin's center appears to have made landfall a little to the south of Barahona, Dominican Republic, shortly before 1200 UTC, and it is now moving northward over the mountainous terrain of the country. Heavy rains have likely overspread much of Hispaniola, although the deepest convection is occurring along the south-central coast of the island. It is assumed that the maximum winds have decreased now that the center is over land, and the initial intensity is set at 35 kt, which is close to the latest UW-CIMSS AiDT and D-PRINT estimates. Franklin's speed has picked up a bit, and it is moving toward the north (005 degrees) at 11 kt. The storm continues to move northward through a break in the subtropical ridge, but it is expected to turn northeastward in the next 24-36 hours when it becomes positioned near the southern extent of a large mid-latitude trough over the western Atlantic. Then, in about 3 days, the central Atlantic ridge is expected to strengthen and block Franklin's eastward progress, forcing the storm to turn toward the north by days 4 and 5. The track guidance is tightly clustered during the first 60-72 hours of the forecast, and the NHC track forecast is very close to the previous prediction and the various consensus aids. After 72 hours, the guidance suggests that the northward turn may be a little delayed. In response, the NHC track has been shifted a bit to the east of the previous forecast at days 4 and 5. Franklin will still be affected by moderate-to-strong west-southwesterly shear when it moves off the coast of Hispaniola later today, so it will likely take some time for the circulation to reorganize itself after moving over the rugged terrain. Otherwise, environmental conditions should support gradual strengthening starting in about 24 hours. In about 3 days, a developing upper-level low near the Bahamas is likely to provide a more favorable diffluent environment aloft over Franklin, potentially fostering more significant strengthening. Although there is a fairly wide range of intensity possibilities in the deterministic and ensemble intensity guidance on days 3-5, the overall guidance envelope has been trending higher. The NHC intensity forecast follows that tendency and is higher than the previous forecast on days 4 and 5. KEY MESSAGES: 1. Heavy rainfall from Franklin is expected across much of Hispaniola into Thursday, which is expected to produce significant and potentially life-threatening flash and urban flooding as well as mudslides, particularly over central Hispaniola. 2. Franklin is bringing tropical storm conditions to portions of the Dominican Republic and Haiti, where Tropical Storm Warnings are in effect, and tropical storm conditions are expected to begin within the Turks and Caicos Islands later today or tonight. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 18.9N 70.9W 35 KT 40 MPH...OVER DOMINICAN REPUB. 12H 24/0000Z 20.5N 70.4W 35 KT 40 MPH...OVER WATER 24H 24/1200Z 22.1N 69.5W 40 KT 45 MPH 36H 25/0000Z 22.8N 68.2W 50 KT 60 MPH 48H 25/1200Z 23.1N 67.0W 55 KT 65 MPH 60H 26/0000Z 23.4N 66.0W 60 KT 70 MPH 72H 26/1200Z 24.3N 65.7W 65 KT 75 MPH 96H 27/1200Z 27.3N 66.7W 80 KT 90 MPH 120H 28/1200Z 31.1N 67.6W 90 KT 105 MPH $$ Forecaster Berg

Canada only, if that. EPS west/GEFS east. The means have been offshore, however, and have generally shifted more in that direction the last 24 hours.

Oh it’s definitely still worth watching in NS. Small upper level changes could still make a big difference for Atlantic Canada—whether that’s more direct impact or no impact at all.

This is really excellent.

Hermine

Yeah, for now at least. Euro is faster with intensification after landfall but guidance has been waivering back and forth on that.

Joaquin or Hermine? If it missed I don’t remember it

Gotta wonder if there will be a reformation after landfall.

Well the Euro keeps Atlantic Canada on the table. Still worth watching closely there.