WxWatcher007

Sam is one of the greats. An all-timer.

Falcons suck

Lemon now for the area in the SW Atlantic. Signal still doesn’t look particularly strong.

Atlantic Basin Update--10/1/21 Recap August was a busy month, with numerous US landfalls. September, however, was a month of contradictions. It was quieter in the landfall department, but we had Hurricane Larry make landfall in Atlantic Canada, Hurricane Nicholas make landfall in Texas, and Tropical Storm Mindy make landfall in Florida. We saw a lot of slop--with 9 named storms this season that lasted 2 days or less, the most since 2007. We also saw Major Hurricane Sam, which is only the 8th hurricane since 1966 to last more than one week at major hurricane strength according to Phil Klotzbach at CSU. Unfortunately, part of my forecast for the peak season between Aug 20 and Oct 20 is going to be a bust, with the number of named storms fully decoupling from my hurricane and major hurricane prediction. With Victor failing to reach hurricane status, that really locks up that fail. Peak Season Forecast (Actual) Named Storms: 13 (12) Hurricanes: 9 (4) Major Hurricanes: 5 (3) Image courtesy of Philip Klotzback & CSU Overview Tropical Storm Victor is likely to be the last Cape Verde (CV) system of the season. The MDR between the Antilles and coast of Africa, after struggling to develop positive SST anomalies during the early part of the season, warmed fairly dramatically during September, extending the traditional CV season through the end of September. That doesn't mean that we won't see more activity, as I expect strong waves to continue pushing through the region through the first two-thirds of October as the MJO remains favorable. Now, climatology shifts quickly toward the homebrew region of the SW Atlantic and western Caribbean. Shear Shear will be a critical factor in whether we see an active October. In a cool neutral ENSO, shear decreases in the Caribbean, and although shear looks strong currently, there does look to be a window approximately a week from now in the western Caribbean. The gif below shows 5-day anomaly averages, so a window can (and I think will) form in between this. In fact, looking at the daily numbers, the GEFS pops a window in the SW Atlantic and western Caribbean in approximately ten days. TCHP/OHC This area of the basin tends to be the warmest, and that's no different here. Although the depth of the heat is less than the outrageous 2020 season, the extent of the warmth is actually a little larger than 2020, particularly in the Gulf and along the SE coast. This heightens the risk for hurricanes and major hurricanes, provided disturbances can develop in a window of reduced shear. The western part of the basin will likely need to wait until the suppressed phase of the CCKW passes this week, but we're already starting to see a growing signal for development in the long range. Steering Pattern Going back to my steering pattern discussion on September 11th, I didn't make the best call lol. The recurves continued, though Larry did find a way to make landfall in Atlantic Canada. The short lived Odette was shunted off the east coast while Sam has stayed well out to sea. I think this is because we had too much activity in the basin. The ridging was there, but with so many weak systems and non-tropical lows/troughs weakening the central Atlantic ridge, anything developing in the basin has followed the weakness well out to sea. October gets complicated. On one hand, homebrew systems, especially in the western Caribbean, greatly increase landfall odds with so many landmasses nearby. On the other, October brings more fronts and troughs that become kickers for systems trying to move westward. The caveat to that, is the prevalence of cutoff lows we've seen so far. As a result, I'm a bit gun shy on landfall chances in October, though I do not think the US is done at all with threats. That's normal. The EPS and GEFS show ridging likely being dominant for the first two-thirds of the month, increasing chances of close calls off the SE coast or landfalls in the Caribbean, but we really need to see what the in-situ steering pattern is before having greater confidence in calling for anything higher than the climatological average of landfall IMO. Atlantic Areas of Interest Currently, there is no specific disturbance to focus on. In fact, the NHC does not have a even a lemon in the basin for the first time in a while. I know the GFS is showing development, but just as I tell folks to be careful when there isn't a surface signal on the operational guidance, be careful of the GFS being overzealous in developing western Caribbean phantoms as well this time of year. Analyze the environment and look for the subtle signal. There are two zones to watch. 1) Western Caribbean--This isn't a surprise as climo starts to favor it, but in the next 7-10 days we could see some development in the region as a tropical wave in the eastern Caribbean moves west and slows down. I'd lean toward the latter end of this 7-10 day range, as we see the suppressed stage of the CCKW/MJO. 2) Western Atlantic--This is a more tricky signal to decipher, as I think it may be driven by what happens in the Caribbean. The guidance tries to sharpen some type of wave or disturbance next week, but while the GFS is slower and more aggressive off the SE coast, the Euro and others keep things broad and unable to develop. Worth watching casually, but a lower shot deal at this point. October is often the last hurrah for hurricane season. Happy hunting.

Super helpful, thanks. I can use some of this vacation time I never got to use for hurricane season.

Oof. I want to get up there but I'm balking at sitting in traffic lol. Would traffic be substantially better if I came up during a weekday?

Smuggler’s Notch?

I thought they were talking about the Avengers and quickly went to totally stumped.

No matter what happens, you should know your contributions are appreciated. I’m sure I’m not the only one that feels this way.

Yeah, it’s over.

I just need 10 mph more

Longest lived major in the Atlantic since 2017. Very impressive.

What an awesome storm. Back near peak intensity.

My place is outrageous with holding heat. One day this August I went to work without timing the AC and when I got home that night it was 93 inside. Brutal.

Product: Air Force Vortex Message (URNT12 KNHC)Transmitted: 30th day of the month at 4:27ZAgency: United States Air Force Aircraft: Lockheed WC-130J Hercules with reg. number AF96-5302 Storm Name: SamStorm Number & Year: 18 in 2021 (flight in the North Atlantic basin)Mission Number: 13Observation Number: 03 ( See all messages of this type for this mission. )A. Time of Center Fix: 30th day of the month at 4:02:10ZB. Center Fix Coordinates: 20.71N 58.58WB. Center Fix Location: 513 statute miles (826 km) to the ENE (72°) from San Juan, Puerto Rico (U.S.).C. Minimum Height at Standard Level: 2,594m (8,510ft) at 700mbD. Minimum Sea Level Pressure: 943mb (27.85 inHg)E. Dropsonde Surface Wind at Center: From 360° at 10kts (From the N at 12mph)F. Eye Character: ClosedG. Eye Shape: Elliptical (oval shaped)G. Orientation of Major Axis in Elliptical Eye: 200° to 20° (SSW to NNE)G. Length of Major Axis in Elliptical Eye: 30 nautical miles (35 statute miles)G. Length of Minor Axis in Elliptical Eye: 26 nautical miles (30 statute miles)H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 111kts (127.7mph)I. Location & Time of the Estimated Maximum Surface Wind Inbound: 7 nautical miles to the WSW (252°) of center fix at 4:00:00ZJ. Maximum Flight Level Wind Inbound: From 353° at 120kts (From the N at 138.1mph)K. Location & Time of the Maximum Flight Level Wind Inbound: 10 nautical miles (12 statute miles) to the WSW (251°) of center fix at 3:59:00ZL. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 99kts (113.9mph)M. Location & Time of the Estimated Maximum Surface Wind Outbound: 23 nautical miles (26 statute miles) to the NE (49°) of center fix at 4:09:00ZN. Maximum Flight Level Wind Outbound: From 140° at 139kts (From the SE at 160.0mph)O. Location & Time of the Maximum Flight Level Wind Outbound: 17 nautical miles (20 statute miles) to the NE (50°) of center fix at 4:07:00ZP. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 9°C (48°F) at a pressure alt. of 3,050m (10,007ft)Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 18°C (64°F) at a pressure alt. of 3,030m (9,941ft)R. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F)R. Sea Surface Temp (collected at same location as temp inside eye): Not AvailableS. Fix Determined By: Penetration, Radar, Wind, Pressure and TemperatureS. Fix Level: 700mbT. Navigational Fix Accuracy: 0.02 nautical milesT. Meteorological Accuracy: 1 nautical mileRemarks Section: Maximum Flight Level Wind: 139kts (~ 160.0mph) which was observed 17 nautical miles (20 statute miles) to the NE (50°) from the flight level center at 4:07:00Z

Look at those FL winds. 137, 138, 139kt FL winds in the NE eyewall. SFMR don’t correspond but extrapolated pressure down to 940mb.

This is one of the great examples in recent memory for me at least of being able to merge days of recon data and satellite/microwave data. This’ll be great for researchers.

Signal looks a little stronger for some weak development in the homebrew region next week. CV season likely ends with 90L.

Yeah it’s not earth shattering. 98 ACE as of yesterday in the Atlantic, or 110% of climo to date.

I think it means you can cancel winter extra early this year.

Was popping in to say I hope I can get a good LES chase this season and y’all are talking tropical! Originally it looked like we’d see some SE Canada ridging and a cutoff low south of New England that could force a close approach by Sam, but the guidance quickly shifted to bring the trough over NE. That does two things: first, it allows for a much cooler NW/northerly flow that’s persistent as the trough slowly meanders over or just east of the region and 2) keeps Sam out to sea or pulls it into Newfoundland.

As impressive as the rapid intensification was, the period of weakening has been fascinating as well. It looks like the ERC, which reorganizes a hurricane's inner core, provided the opening for relatively light shear to impart dry air into the more vulnerable core, causing significant disruption.

It has recovered a bit in the last few frames (not shown above), but it’s really fascinating to contrast how the inner core rapidly organized yesterday to what we’ve seen this evening.