GaWx

I’ve found only three storms on record since the late 1800s that have formed in the MDR E of 50W Sep 20+ and hit the CONUS: 1) 2002’s Lili: TD formed 9/21 near 45W and hit LA 10/3 as a H; El Nino 2) 1966’s Inez: TD formed 9/21 near 35W and hit FL Keys 10/4 as a H; not El Niño 3) 1893’s storm #9 formed 9/25 near 25W and hit Carolinas 10/13 as a MH; not El Nino

12Z UKMET had this (0Z is further down in this post): NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 54 HOURS FORECAST POSITION AT T+ 54 : 14.5N 27.2W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 22.09.2023 60 14.5N 29.0W 1008 31 1200UTC 22.09.2023 72 15.0N 32.2W 1007 32 0000UTC 23.09.2023 84 15.3N 34.9W 1006 36 1200UTC 23.09.2023 96 15.8N 37.9W 1005 38 0000UTC 24.09.2023 108 16.3N 39.9W 1005 37 1200UTC 24.09.2023 120 16.7N 42.4W 1004 44 0000UTC 25.09.2023 132 17.4N 44.3W 1003 47 1200UTC 25.09.2023 144 17.3N 46.7W 1003 48 0000UTC 26.09.2023 156 17.2N 48.9W 1003 47 1200UTC 26.09.2023 168 17.1N 49.9W 1001 60 ——————— 0Z UKMET: At 168 hours TS moving W at 15 mph 300 mi NE of Leewards NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 60 HOURS FORECAST POSITION AT T+ 60 : 15.0N 33.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 22.09.2023 60 15.0N 33.7W 1009 30 0000UTC 23.09.2023 72 15.6N 36.3W 1008 30 1200UTC 23.09.2023 84 16.0N 39.3W 1008 31 0000UTC 24.09.2023 96 16.3N 41.7W 1008 30 1200UTC 24.09.2023 108 16.4N 43.6W 1007 37 0000UTC 25.09.2023 120 17.2N 46.4W 1007 36 1200UTC 25.09.2023 132 17.8N 49.2W 1008 37 0000UTC 26.09.2023 144 18.3N 52.1W 1008 42 1200UTC 26.09.2023 156 18.6N 55.5W 1007 42 0000UTC 27.09.2023 168 18.4N 58.2W 1005 37

More on these amateur forecasts with most warm, dry in the NW and cold, snowy E coast: Weather Watcher: what a winter along E coast! Weather William: winter will be rockin’ in the east! Direct Wx: get your shovels ready in the east! America Climate Channel: amazing winter for the east! NWW116 goes big in the east! AWF: Lives in GA and has their coldest and one of snowiest winters of last 45 yrs 2009-10 as top analog! Weather At A (15 minute long) Glance: David S for NE: probably one of worst winters; “big, deep trouble, almost historic, winter-mageddon”! MBGC says wild winter coming, especially NE; 2009-10 favorite analog! Direct Wx’s favorite video of year: official snowfall forecast with snow to Savannah!!

Yes, in locations away from where the forecaster lives. That’s the key. Not necessarily exactly as you stated, but a “benign” winter. For example, literally every amateur forecast I’ve seen so far for this winter from those not living in the W, which includes just about every forecast I’ve seen, has the W mild/benign and the E cold along with AN snow. They’re all almost carbon copies of each other’s forecast. Their forecasts are much more predictable than what they’re trying to predict. This is influenced a lot by weenieism as well as the desire to get more clicks. Their bias dominates. I should emphasize that I’m talking about the amateur forecasters that I’ve seen so far. I’m not at all talking about objective amateur and pro forecasters without a hidden agenda who put the desire for accuracy ahead of weenieism and getting clicks.

The BOM and CFS have both been overdoing the MJO, especially in and near phase 5, since at least spring. The CFS has recently been forecasting a phase 5 in early OCT but is now staying inside the COD.

Yeah it only skirts the NC OB. But even so, a few areas in E NC get up to 4-8” of rainfall on the Euro: https://www.pivotalweather.com/model.php?m=ecmwf_full&p=qpf_120h-met&rh=2023091912&fh=132&r=nwatl&dpdt=&mc=

The 12Z Euro op at hour 90 near 100 miles E of N FL is on the SW side of the EPS member envelope as the EPS mean is 100 miles NE of there: https://www.pivotalweather.com/model.php?m=epsens&p=sfcmslp-meanmem&rh=2023091912&fh=90&r=us_se&dpdt=&mc=

Looks pretty close to a STS at hour 90 of the 12Z Euro centered off N FL. Note the 35 knot wind barbs off N FL/GA/SC and the good organization and low SLP of 1002 mb: https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sfcwind_mslp&rh=2023091912&fh=90&r=swatl&dpdt=&mc=

Looks pretty close to a STS at hour 90 of the 12Z Euro centered off N FL. Note the 35 knot wind barbs off N FL/GA/SC and the good organization and low SLP of 1002 mb: https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sfcwind_mslp&rh=2023091912&fh=90&r=swatl&dpdt=&mc=

The SOI is at 31 days in a row of negative dailies, the longest streak so far this year. The 30 day average is back down to ~-15, indicative of solid El Niño atmospheric conditions. In general, Nino 3.4 has tended to warm during the several weeks following long solid -SOI periods like this although there’s lots of variation. The OISST SSTa daily graph shows new highs in both 3.4 and 4 today with 3.4 near +1.7. I expect warming to dominate for the next few weeks meaning a decent shot at 3.4 reaching +2.0 on the OISST dailies in early Oct: https://www.longpaddock.qld.gov.au/soi/ ##Corrected to say new highs in 3.4 and 4

After the 0Z run not turning this into a TC and the prior 12Z having it become a TC but staying offshore, this new 12Z UKMET is back to having a TC, is a bit stronger, and it moves N to a landfall near the NC OB Saturday 9/23 followed by a crawl up the coast to DelMarVa pen/dissipation on Mon 9/25. This very slow movement and track is likely bringing very heavy rains to the mid-Atlantic coastal area: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 78 HOURS FORECAST POSITION AT T+ 78 : 32.5N 77.0W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 23.09.2023 84 32.7N 76.4W 1006 47 1200UTC 23.09.2023 96 35.4N 76.1W 1003 42 0000UTC 24.09.2023 108 37.3N 76.3W 1001 40 1200UTC 24.09.2023 120 37.9N 76.2W 1007 33 0000UTC 25.09.2023 132 37.7N 76.1W 1012 32 1200UTC 25.09.2023 144 38.2N 75.7W 1015 32 0000UTC 26.09.2023 156 CEASED TRACKING

Has anyone seen this map of the correlation between DJF ONI and DJF snowfall? I’ve studied Atlanta extensively and I can vouch for the ~+0.25 there. What about other locations?

The late August peak was ~Aug 25th, which coincides with the first image in this OHC animation (average of 5 days ending Aug 27th). From then to just about all of the way to the end, this animation mainly shows slow cooling and still doesn’t show any signs of another round of significant OHC rewarming being imminent at the end. In contrast the loops ending in early August clearly showed strong rewarming about to commence, which of course happened. There’s still time (~remainder of autumn) but I’m admittedly saying to myself “hmmm” because I didn’t expect a 3 week long slow cooling/pause of OHC along with still no sign of it ending. And now BoA finally cooled significantly for its 3.4 peak and thus joined the cooling vs one month ago runs party although @snowman19correctly pointed out that its initialization was too cool.

The SSTa image below from Sep 13th shows that significant cooling of the upper ocean resulting from slow moving large and major H Lee stirring up the waters started well before center passage. Note that at 11AM EDT on Sep 13th Lee was still down at 26.4N, 67.2W, despite a new blue area that stretches as far NW as 29N, 69W, that was yellow the prior day. So, the SST had already cooled ~1F all the way up at 29N, 69W, vs 24 hours earlier even though the center was still over 200 miles to the SE at the end of that 24 hours. The center didn’t even get near 29N, 69W, for another ~18 hours, during which that area and nearby cooled more. During the analyzed period, Lee was moving under 10 mph and getting larger. I was educatedly guessing that Lee’s slow movement combined with large size was helping to keep its strength in check by causing SST cooling well ahead of the center. I assume that a little cooling well ahead of a center would be normal but this appears to have been more than average cooling due to a combo of slow movement and large size:

Coolest/lowest dewpoints of any day in months! Hope to walk outside!

Interesting point. It is initializing Sep to date at only ~+1.35 vs the actual of ~+1.5-1.55.

12Z UKMET: unlike 0Z that forms S of Charleston and then moves NNE into NC, this forms just off NC followed by NNE, NE, and ENE movement to well offshore the NE US/Canada that never allows it to landfall anywhere through hour 168: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 120 HOURS FORECAST POSITION AT T+120 : 34.9N 74.9W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 23.09.2023 120 34.9N 74.9W 1005 36 0000UTC 24.09.2023 132 37.3N 73.8W 1005 36 1200UTC 24.09.2023 144 38.9N 71.2W 1009 33 0000UTC 25.09.2023 156 39.4N 67.9W 1011 30 1200UTC 25.09.2023 168 39.6N 62.3W 1013 34

I went ahead and created a new thread on this potential late week offshore SE US STC/TC here:

The models are pretty much unanimous in developing a non-tropical surface low off of the SE US coast late this week that could then transition into either or both a STC and a TC. Ultimately, the biggest impact to land could end being heavy rain well up the E cost as @jconsorhas mentioned elsewhere. I found these seven TCs that formed from a nontropical origin that later hit the SE US as an H: -Arthur 2014: early July; developing weak Nino; cat 2 into NC -Gaston 2004: late Aug; weak Niño; cat 1 into SC -Diana of 1984: early to mid Sep; incoming Nina; cat 2 into NC after being cat 4 offshore -Cindy of 1959: early Jul; neutral ENSO; cat 1 into SC -Yankee Hurricane of 1935: formed from nontropical low E of Bermuda Oct 30 that hit SE FL as a cat 2 H Nov 4th! Warm neutral ENSO -Storm #5 of 1913: early Oct; formed from nontropical low off NE US and hit SC as cat 1/developing Nino -Storm #2 of 1898: late Aug; cold neutral; cat 1 into GA So, a TC that is purely nontropical in origin has resulted in a landfalling H on the SE US coast ~every 18 years on average over the last 125 years. The strongest landfalls were the three cat 2 hits: Arthur of 2014, Diana of 1984, and the Yankee H of 1935. Landfalls: 3 SC, 2 NC, 1 GA, 1 FL TS landfalls on the SE coast from nontropical origins have occurred much more often than the once/18 years of H landfalls. But that’s intuitive because it typically takes a good bit of time for transition to tropical and there often isn’t a lot of time over water with them developing close to home. There have been 12 in 73 years or ~1 every 6 years on average. So, these stats suggest that the chance of a nontropical originating TC landfalling on the SE US as a TS is ~3 times higher than landfalling there as a H: 2022: Colin 2021: Danny 2015: Ana 2007: Gabrielle 2002: Kyle 1981: Bret 1976: Dottie 1967: Doria 1965: #9 1962: #2 1960: Brenda 1952: #3 To clarify for the readers, the stats I presented are only for those that actually made landfall on the SE US. So, they wouldn’t apply, say, to any that go NE and stay offshore, which may increase the chance for a H vs those that hit the SE. Based on everything I’ve seen for the current situation along with my analysis of over seven decades of history, I predict that IF this were to ever transition to a TC and IF it then were to landfall on the SE US that it would landfall there as a TS rather than a H. Also, if it were to landfall there, I predict either NC or SC with further N in SC favored over further S. This doesn’t look to me like a FL or GA landfall though nothing is certain because nothing is ever certain especially this far out. Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Mon Sep 18 2023 Western Atlantic: A non-tropical area of low pressure is forecast to form near the southeastern coast of the United States late this week. This system could acquire some subtropical characteristics this weekend if it remains offshore while it moves slowly northward or northwestward. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 7 days...low...30 percent. 0Z UKMET has a strong TD/weak TS from this that landfalls in NC. The strength of this model for an undeveloped potential storm is nearly always conservatively low. Thus, I’d take its strong TD/weak TS forecast with a grain and figure that a mid grade STS/TS would be just as likely: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 126 HOURS FORECAST POSITION AT T+126 : 30.6N 79.9W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 23.09.2023 132 31.7N 78.8W 1002 32 0000UTC 24.09.2023 144 34.4N 78.1W 1002 33 1200UTC 24.09.2023 156 37.8N 77.5W 1006 34 0000UTC 25.09.2023 168 40.6N 76.6W 1007 23

Thanks, Yaakov. To clarify for the readers, the stats I presented are only for those that actually made landfall on the SE US. So, they wouldn’t apply to any that go NE and stay offshore, which may increase the chance for a H vs those that hit the SE. Based on everything I’ve seen for the current setup along with my analysis of over seven decades of history, I predict that IF this were to ever transition to a TC and IF it then were to landfall on the SE US that it would landfall there as a TS. Also, if it were to landfall there, I predict either NC or SC with further N in SC favored over further S. This doesn’t look to me like a FL or GA landfall though nothing is certain because nothing is ever certain especially this far out.

The SOI has gone 29 straight days with a negative.

As I expected, Nino 3.4 came in again at +1.6. Nino 3 and 4 were also unchanged. Nino 1+2 not at all surprisingly based on following the dailies dropped to +2.6 though I would have guessed +2.7: https://www.cpc.ncep.noaa.gov/data/indices/wksst9120.for

I found several more including Arthur of early July of 2014 with mesoscale complex origin in the GOM and Cindy of early July of 1959 (not El Niño), which formed from a nontropical low along a cold front off FL. So, for the SE so far: -Arthur 2014: early July developing weak Nino cat 2 into NC -Gaston 2004: late Aug weak Niño cat 1 into SC -Diana of 1984: early to mid Sep incoming Nina cat 2 into NC -Cindy of 1959: early Jul neutral ENSO cat 1 into SC -Yankee Hurricane of 1935: formed from nontropical low E of Bermuda Oct 30 that hit SE FL as a cat 2 H Nov 4th! Warm neutral ENSO -Storm #5 of 1913: early Oct formed from nontropical low off NE US and hit SC as cat 1/developing Nino -Storm #2 of 1898: late Aug cold neutral into GA cat 1 *Edited to add several more including Yankee Hurricane of 1935 (based on link below) and storm #5 of 1913 So, a TC that is purely nontropical in origin has resulted in a landfalling H on the SE US coast ~every 18 years on average over the last 125 years. The strongest landfalls were the three cat 2 hits, Arthur of 2014, Diana of 1984, and the Yankee H of 1935. Landfalls: 3 SC, 2 NC, 1 GA, 1 FL My educated guess based on recollection is that TS landfalls on the SE coast from nontropical origins have occurred a good bit more often than the once/18 years of H landfalls. But that’s intuitive because it typically takes a good bit of time for transition to tropical and there often isn’t a lot of time over water with them developing close to home. Edit: I was able to confirm a much higher frequency of SE TS landfalls vs H landfalls from a non-tropical origin: 12 in 73 years or ~1 every 6 years on average. So, chances of a nontropical originating TC landfalling on the SE US as a TS are ~3 times higher than that for a H: 2022: Colin 2021: Danny 2015: Ana 2007: Gabrielle 2002: Kyle 1981: Bret 1976: Dottie 1967: Doria 1965: #9 1962: #2 1960: Brenda 1952: #3 https://en.m.wikipedia.org/wiki/1935_Yankee_hurricane

Thank you. Indeed, Gaston (what you meant) of late August of 2004, in this case during a weak El Niño, joins Diana and late Aug of 1898 as a nontropical origin TC that then moved into the SE US as an H. Looking to see if I find more. Bob of 1991 was nontropical that hit the NE as a H. But I was looking for those that hit NC south.

This only quite vaguely resembles 1984 (Diana), which originated from the tail end energy on a rather strong cold front going offshore/nontropical which quickly became tropical. But 1984 was an extremely rare storm (100+ year storm?) and it occurred two weeks earlier during heart of the season. I don’t look for anything like that of course and this could easily turn out to be no big deal other than a good rainfall producer for some areas. However, in the extreme, this could be a STD/STS that becomes a TC (especially if it then moves NE offshore). Regardless, it is an interesting situation due to uncertainty. Edit: late August of 1898 may have been somewhat similar to 1984 that also became a hurricane that came back into the SE coast. Neither 1898 nor 1984 was during El Niño by the way. I’ll look to see if I can find more. But those are two of the most extreme cases off the top of my head. This is more or less a potential “ridge over troubled waters” setup where a rather strong surface high to the north provides lower level convergence to the south, which leads to lift and then the formation of a sfc low.