GaWx

Last 6 EPS runs (0Z and 12Z only): # of members with CONUS H landfall 12Z 9/6: 3 (6%) (ME 9/15 & 9/17, MA 9/18) 0Z 9/6: 5 (10%) 12Z 9/5: 2 (4%) 0Z 9/5: 4 (8%) 12Z 9/4: 1 (2%) 0Z 9/4: 2 (4%) So, the latest run dropped from 10% to 6%. The chance remains low.

That makes sense. But is there an alternative possibility, that of potential Margot helping to pump up the ridge to its NW and then leading to an omega block that forces Lee into the NE like was the case with Sandy? (See my post above showing the omega block that affected Sandy). I'll repost the Sandy omega block image:

I agree that that's bad because it takes away from objectivity. But equally bad is doing the opposite. I strive for a happy medium of sorts.

Saying there's still a small chance for a NE hit isn't wish-casting. It's the truth because nobody can possibly know with certainty this far out that Lee won't hit there. Do I think it will hit there? No, due to strong odds imo that it won't. Will I say the NE is safe from a hit? No, because there's still a 20% or so chance imo for a hit somewhere in the NE though that % is continually adjusted up and down. Biases in forecasting, whether bullish or bearish, are common. My goal here is to try to be as objective as possible based on the model data and other facts like history/analogs, try to generate interesting forecasting discussions, etc. This storm isn't even going to come close to directly affecting me way down here barring something really crazy. Furthermore, I wouldn't want this coming anywhere close to here. On another note, I'd like to know whether or not Sandy is an analog to consider for potential forecasting difficulties regarding the NE US. I don't mean that this is necessarily going to be another storm with as big of an impact as Sandy had should it actually hit. I'm just wondering if the possibility of a left hook into the NE is being considered as a small possibility. Although the Euro did well a week out showing the hook as I recall, other models didn't. So, is this an analog to just consider or not? Opinions?

Are you talking about the US? If so, there are a couple of hits (NE US) in addition to some on SE Canada. The chance of a US hit remains low but there is a chance.

Just through 240, the 12Z EPS appears to be fairly similar to the 0Z. It has one H hit the ME/NB border on 9/15, one hit S Nova Scotia, several more aiming for the NE/SE Canada, and a few much further S including one H and 2 TS in the Bahamas. I'll check the entire run later when it comes out.

12Z Euro at 168 is ~200 miles SSE of the 0Z at 180.

The 12Z Euro at 132 is ~150 miles SSE of the 0Z at 144 and isn't quite as strong though it is still a beast.

The 12Z UKMET is similar to the 0Z and thus the ~200 mile E shift of today's 0Z vs yesterday's more ominous 12Z was maintained. Regardless, I maintain there's still a chance for the NE US to be hit albeit a small chance. When I say small, I mean something like 20%, which is nothing to take lightly as they're nowhere near safe at this point. Although the highest % of Euro ens members hitting the NE US so far (through today's 0Z run) is 10%, I'm still at double that due to how far out in time it still is. At 168, the 12Z UKMET has Lee ~250 miles NE of the SE Bahamas moving NNW: TROPICAL STORM LEE ANALYSED POSITION : 13.7N 44.8W ATCF IDENTIFIER : AL132023 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 06.09.2023 0 13.7N 44.8W 1003 43 0000UTC 07.09.2023 12 15.3N 46.6W 1002 43 1200UTC 07.09.2023 24 16.3N 49.3W 1000 41 0000UTC 08.09.2023 36 17.0N 51.8W 1000 40 1200UTC 08.09.2023 48 17.7N 54.6W 997 55 0000UTC 09.09.2023 60 18.3N 57.0W 997 52 1200UTC 09.09.2023 72 19.1N 59.3W 997 53 0000UTC 10.09.2023 84 19.7N 61.1W 997 55 1200UTC 10.09.2023 96 20.0N 63.1W 994 57 0000UTC 11.09.2023 108 20.6N 64.4W 994 53 1200UTC 11.09.2023 120 20.9N 65.6W 994 53 0000UTC 12.09.2023 132 21.7N 66.8W 991 56 1200UTC 12.09.2023 144 22.6N 67.3W 985 50 0000UTC 13.09.2023 156 23.4N 68.4W 978 52 1200UTC 13.09.2023 168 24.2N 68.9W 973 61

Whereas winter -NAOs have been much less frequent in recent decades than they had been, summer -NAOs have done the opposite and have increased markedly. % of summer months with NAO<0: increased 1950-97: June: 50% July: 42% Aug: 46% 1998-2023 June: 73% July: 65% Aug: 73% % of winter months with NAO<0: decreased 1950-97: Dec: 42% Jan: 48% Feb: 46% 1998-2022/3: Dec: 36% Jan: 20% Feb: 27% So, whereas summer and winter -NAO month frequencies were about the same during 1950-97, summer -NAO months since 1998 have been 2.5 times as frequent as winter -NAO months! Thus, having a summer -NAO (at least based on recent decades) doesn't at all increase the chance for a subsequent winter's -NAO. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

The 6Z Euro hour 72 is slightly E of 0Z 78 and similar to yesterday's 12Z at 90.

Not the same, but you can bet on weather via weather futures and options: https://www.cmegroup.com/trading/weather/files/weather-futures-and-options-fact-card.pdf

Last 5 EPS runs (0Z and 12Z only): # of members with CONUS H landfall 0Z 9/6: 5 (10%) 12Z 9/5: 2 (4%) 0Z 9/5: 4 (8%) 12Z 9/4: 1 (2%) 0Z 9/4: 2 (4%) So, although still a small %, the latest run has the highest yet.

The 0Z UKMET is a bit stronger. But more importantly, it is recurving 200 miles E of the 12Z run thus implying a significantly lower risk of landfall to the CONUS. Whereas two runs ago it was in the SE Bahamas and the last run was just N of the SE Bahamas, this run is ~250 miles NE of those islands: TROPICAL STORM LEE ANALYSED POSITION : 13.8N 42.1W ATCF IDENTIFIER : AL132023 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 06.09.2023 0 13.8N 42.1W 1008 27 1200UTC 06.09.2023 12 14.1N 44.7W 1006 37 0000UTC 07.09.2023 24 15.3N 46.9W 1004 41 1200UTC 07.09.2023 36 16.4N 49.5W 1003 34 0000UTC 08.09.2023 48 17.0N 52.2W 1003 35 1200UTC 08.09.2023 60 17.7N 54.9W 1002 42 0000UTC 09.09.2023 72 18.4N 57.9W 1000 45 1200UTC 09.09.2023 84 18.8N 60.2W 1000 48 0000UTC 10.09.2023 96 19.8N 62.1W 998 53 1200UTC 10.09.2023 108 20.5N 64.2W 998 55 0000UTC 11.09.2023 120 20.8N 65.6W 997 54 1200UTC 11.09.2023 132 21.2N 67.0W 996 52 0000UTC 12.09.2023 144 22.0N 67.7W 993 54 1200UTC 12.09.2023 156 23.3N 68.0W 987 51 0000UTC 13.09.2023 168 24.4N 68.9W 977 56

The 12Z Korean has a 940 mb MH at 276 just S of Long Island that then slams Suffolk County 9/16-7: https://weather.us/model-charts/korea/2023090512/usa/sea-level-pressure/20230917-0000z.html

The 12Z UKMET is 250++ miles west of all of the 12Z GEFS members except for that one on the left, which it is close to.

Eyeballing it tells me the new Euro ONI peak is near or just under +2.25 for NDJ vs +2.40 on the prior run. Feb is ~+2.05. So, although still well within super peak strength, it did drop slightly. CFS dropped more than slightly vs a few weeks ago but it is an inferior model.

12Z UKMET 162-168 shows start of recurve but much closer to SE than other models implying a potential problem for NC north after run ends considering that it is recurving at least 5 degrees (~300 miles) further west than GFS: scroll down to see each map SLP 162 https://weather.us/model-charts/gbr/2023090512/middle-america/sea-level-pressure/20230912-0600z.html SLP 168 https://weather.us/model-charts/gbr/2023090512/middle-america/sea-level-pressure/20230912-1200z.html H5 at 162 https://weather.us/model-charts/gbr/2023090512/north-america/geopotential-height-500hpa/20230912-0600z.html H5 at 168 https://weather.us/model-charts/gbr/2023090512/north-america/geopotential-height-500hpa/20230912-1200z.html Edited

12z Euro at hour 180 ~75miles SSW of 0Z 192 with 925 mb but still recurving (along 67W).

That looks like a -NAO being predicted by this Euro run for DJF averaged out based on a just over 1 mb AN SLP at Iceland and a just over 1 mb BN SLP in the Azores. Do you or does anyone else have the 2M temp for DJF? Or can someone provide me a link please?

I agree that it's possible although a steep climb for the next 3.5 weeks to ~+2.2 would be needed. I do see that ERSST caught up to OISST for August as a while vs it being slightly cooler than OISST for many months. So, that ups thise chances somewhat. *Edited for correction*

Even with the 12Z UKMET being 150 miles ENE of its 0Z run at the end, it is at hour 168 still a whopping 350 miles WSW of the 12Z GFS at 168.

-12Z UKMET initialized this at 13.4N, 39.1W vs the Best Track's 12Z of 12.2N, 39.6W. So, the 12Z's initialization is 90 miles NNE of the actual position. -12Z UKMET is stronger and is at hour 156 ~150 miles ENE of the 0Z's hour 168. At 168, the 12Z is N of the SE Bahamas moving WNW at only 5 mph vs the 0Z being in the SE Bahamas: TROPICAL DEPRESSION 95L ANALYSED POSITION : 13.4N 39.1W ATCF IDENTIFIER : AL952023 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 05.09.2023 0 13.4N 39.1W 1011 24 0000UTC 06.09.2023 12 13.8N 42.0W 1009 25 1200UTC 06.09.2023 24 14.2N 44.7W 1007 31 0000UTC 07.09.2023 36 15.3N 46.7W 1007 34 1200UTC 07.09.2023 48 16.4N 49.0W 1006 35 0000UTC 08.09.2023 60 17.5N 52.0W 1006 31 1200UTC 08.09.2023 72 18.5N 55.1W 1007 32 0000UTC 09.09.2023 84 19.4N 58.4W 1006 30 1200UTC 09.09.2023 96 19.9N 61.2W 1005 39 0000UTC 10.09.2023 108 20.6N 63.6W 1003 46 1200UTC 10.09.2023 120 21.4N 66.5W 1002 50 0000UTC 11.09.2023 132 21.9N 68.6W 998 52 1200UTC 11.09.2023 144 22.4N 70.2W 998 50 0000UTC 12.09.2023 156 23.9N 71.0W 996 60 1200UTC 12.09.2023 168 24.2N 72.0W 996 46

I remember it and the Euro both being W of the other models and thus those two doing the best for Irma in FL overall once within 5 or so days of landfall. Actually for Ian last year for both the FL and SC landfalls, the UKMET was further right rather than further left of the model consensus and it did the best. Also, for Idalia, the UK was right of the GFS/CMC and did better. So, I don't know whether or not it still has a too far W bias. Maybe it still does in the longer range out in the MDR though.

.NEW TROPICAL DEPRESSION FORMS IN THE CENTRAL TROPICAL ATLANTIC... ...FORECAST TO BECOME A POWERFUL HURRICANE BY THE END OF THE WEEK... 11:00 AM AST Tue Sep 5 Location: 12.5°N 40.2°W Moving: WNW at 15 mph Min pressure: 1008 mb Max sustained: 35 mph 0Z UKMET initialized 190 miles due east of this