GaWx

Actually, this new CANSIPS run, despite its -NAO, isn't very cold. Where do you see "very cold"? It is for the bulk of the E US (other than the slightly AN in upper Lakes to NNE) near normal (after adjusting to 1991-2020 instead of 1981-2010 baseline), which is oddly enough slightly warmer than the prior run (which was slightly BN in the SE): Of course, near normal would seem very cold relative to most recent winters. I'll take the colder change although I'm hoping for actual BN here in the SE as El Niño provides the best chance for that.

I'm trying to understand the terminology better. At 12:12Z on 8/30, the linked graph for Tampa shows a 6.64 foot tide (red line) that appears to be using MLLW as a reference. It also shows a 1.433 predicted (blue line, which is the astronomical) tide then. In addition, when one clicks on "observed - predicted", it then displays a purple line that was at its max of 5.21 feet at 12:12Z. That's 6.64 ft minus 1.433 ft. So, that appears to be the maximum extra water level caused by the storm. Are you saying that the maximum "observed - predicted" is not the storm surge? If not, what is that called? https://tidesandcurrents.noaa.gov/waterlevels.html?id=8726607&bdate=20230829&edate=20230831&units=standard&timezone=GMT&interval=6

From NWS CHS: "A MAXIMUM TIDE LEVEL OF 3.47 FT MHHW (9.23 FT MLLW) WAS OBSERVED AT THE CHARLESTON HARBOR TIDE GAGE." From the first image linked below, there was a maximum surge of 2.38' at CHS at 8:12 PM on August 30th that coincided exactly with high tide to produce the 9.23 ft tide (in red)/CHS battery flooding: https://tidesandcurrents.noaa.gov/waterlevels.html?id=8665530&units=standard&bdate=20230829&edate=20230831&timezone=GMT&datum=MLLW&interval=6&action= This was made worse by the center being ~50 miles closer to CHS at high tide vs where models had projected it then. Thus the strongest perpendicular SE winds came in and peaked just before and at high tide instead of being much lighter then, which would have been the case had the center been 50 miles further away. OTOH, it being 50 miles closer to CHS at high tide meant 50 miles N of SAV meaning W (offshore) winds at Ft. Pulaski instead of very close to SAV. That result was a major factor that lead to the maximum surge at Ft. Pulaski of 2.7' occurring much earlier at 1:36 PM on August 30th, which was luckily near LOW tide when winds were nearly perpendicular to the coast (ESE winds). Soon after that, winds shifted to SSE (no longer perpendicular and thus not pushing as much water in) and eventually to WSW at the time of high tide literally pushing the high water out. The result was that at the 8:24 PM high tide, the storm surge had shrunk to nearly nothing as per this linked image, which meant at Ft. Pulaski only an 8.95 ft tide vs a 9.4 ft tide (both in red) at the high tide the evening before. So, while CHS was having their worst flooding, Ft. Pulaski and the nearby islands/lowlands around SAV were already back to normal! https://tidesandcurrents.noaa.gov/waterlevels.html?id=8670870&bdate=20230829&edate=20230831&units=standard&timezone=GMT&interval=6 ---------- Edit: My power was out ~10 hours (5PM 8/30-3AM 8/31). I measured under 1" of rain. Closer to the coast got less than well inland, which was well predicted by the models. The airport got ~1.5". Just 50 miles inland from SAV despite the fast storm movement (20 mph), Candler, Bulloch, and Screven counties had flooding from very heavy rainfall as the remnants of the very wet NW eyewall hit that area. Statesboro, Metter, and Newington were deluged with 7-8"! That extended into Allendale, Hampton, and Colleton counties. Some of that scraped CHS (airport well inland), which got 3". There were 3 confirmed EF0 tornadoes, two in the CHS metro (including the one linked to earlier ITT that caused that car to lift in the air) and one in Liberty County, GA. No injuries and minimal damage, fortunately.

Well, I looked at the site linked below and it appears that Tampa may have had a 5.2 ft storm surge at 8:12 AM on August 30th! If this were to verified as accurate, that may be the highest surge at least since the 5 ft from Gladys of 1968! That's pretty amazing considering how far offshore it was and that it landfalled way up in the Big Bend! Can anyone verify this data? https://tidesandcurrents.noaa.gov/waterlevels.html?id=8726607&bdate=20230829&edate=20230831&units=standard&timezone=GMT&interval=6

The typically conservative UKMET (0Z) once again is pretty strong with this E MDR lemon AEW that about all models now develop: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 54 HOURS FORECAST POSITION AT T+ 54 : 10.9N 22.9W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 03.09.2023 60 11.4N 24.8W 1008 37 0000UTC 04.09.2023 72 10.8N 27.6W 1008 32 1200UTC 04.09.2023 84 11.6N 31.6W 1008 31 0000UTC 05.09.2023 96 12.3N 35.1W 1006 34 1200UTC 05.09.2023 108 13.0N 39.3W 1005 35 0000UTC 06.09.2023 120 13.7N 42.6W 1005 31 1200UTC 06.09.2023 132 13.9N 45.5W 1001 37 0000UTC 07.09.2023 144 14.5N 48.1W 1000 39 1200UTC 07.09.2023 156 15.3N 50.6W 997 51 0000UTC 08.09.2023 168 16.2N 53.3W 997 47

Due mainly to Harold and Idalia, much of the Gulf has cooled ~1C over the last two weeks: Aug 17th near record warmth dominated by 31-32C (~88-90F): August 30th: still very warm but much of it cooled ~1C to mainly 30-31C (86-88F) with a small area affected by both storms cooling nearly 2C (32 to 30) near 25-26N, 84-85W:

Great point. Does anyone know what the official Tampa Bay storm surge was?

-Based on the normalized SLP anomaly TT maps of the last two CANSIPS runs, it has ~-0.35 NAO averaged out over DJF on this run vs ~-0.30 on the prior run. A -0.35 NAO would qualify as a -NAO per my requirement of sub -0.25. -If that were to verify, it would be only the 2nd -NAO winter of the last 13 winters and only the 7th of the last 45. -I'd love for this to verify, but I still don't believe the NAO will average that low as I'm predicting either neutral or +NAO. But keeping in mind that neutral goes as low as -0.25, it could end up as neutral and still be close to this -0.35. -The combo of two things is keeping me from forecasting a -NAO DJF. First, we've been in an +NAO winter era the last 44 winters with only 14% of these winters having a -NAO. Second, an approaching solar max and associated expected very high sunspot activity (150+) tells me that this is not a winter to go out on a limb (i.e., going with the 14%) and predict a sub -0.25 NAO. The highest DJF averaged sunspot activity during these pretty rare -NAO winters within the current +NAO era (last 44 winters) was only 33. -CANSIPS of 11/30/22 forecasted a -0.40 NAO for DJF 2022-3 vs the actual +0.68. So, the CANSIPS can be far off and this one was only one day before met winter: -I do think that one sub -0.50 NAO month of DJF is quite possible though (perhaps in Feb). That wouldn't even be that far off from you since you think Dec will suck. And then there's the chance for that also in March, which I'm not even considering since it isn't part of met winter.

PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE CHARLESTON SC 1209 AM EDT THU AUG 31 2023 ..HIGHEST WIND REPORTS FROM IDALIA LOCATION SPEED TIME/DATE PROVIDER SOUTH TYBEE ISLAND 69 MPH 0439 PM 08/30 WXFLOW BEAUFORT 66 MPH 0619 PM 08/30 WXFLOW CALIBOGUE SOUND 64 MPH 0536 PM 08/30 WXFLOW Based on the above from NWS CHS, I'd think 60+ on parts of HH is supported. This data was pulled from here: https://kamala.cod.edu/offs/KCHS/2308310409.nous42.html

This map of the newest DJF Greenland SLP anomaly shows a 2-4 mb anomaly vs 1993-2016 climo. Per TT, the prior CANSIPS run had a 2+ mb anomaly (vs 1981-2010 climo) only in SE Greenland. So, if the different climo bases as well as any other differences of mapping parameters for WCS vs TT aren't making a big difference, I'd then expect the updated TT to show a significantly stronger DJF Greenland SLP anomaly in its update compared to the prior run on TT.

Keep in mind that Nino 4 now being at +1.1 on the OISST, especially with it only August, is on a relative basis vs its own historical ranges super strong. The current +1.1 there is a new record for August.@bluewavehas talked about how warm Nino 4 has been vs its past. The old record warm weekly prior to 2023 was only +0.8 (2015). Warmest Aug wkly Nino 4 back to 1982 OISST +1.1: 2023 +0.8: 2015 +0.7: 2019...outside of El Niño +0.7: 2002 +0.6: 2018, 09, 06, 04, 94 +0.5: 1991, 87 +0.4: 2014, 97 +0.2: 1982 However, some caution is needed with the weekly OISST table when comparing to prior years, especially the further back one goes. That's because they are all based on 1991-2020 averages rather than adjusting more for cooler climo the further back one goes like ONI does. For example, the mere +0.2 of 1982 would be equivalent to something a good bit higher if it were reflecting, say, 1966-1995 averages. Similar idea for the +0.5s of 1987/91. Even the +0.4 of 1997 would be warmer. Note that even the weak Nino of 2018 was able to attain +0.6. Even more notable is the +0.7 of 2019, which is very warm for being past the 2018-9 Nino. So, it is important to keep in mind that 2023's +1.1 is likely helped out by overall GW. If there were an adjustment for simultaneous warming of other areas similar to how RONI has recently been adjusting significantly cooler for ONI, Nino 4 would likely be a fair bit cooler than +1.1. Nino 3 and Nino 1+2 would also be in the same boat.

I was comparing Idalia with 2016's Hermine, which peaked at 80 mph/981 mb 5 hours before FL landfall near where Idalia hit. It went steady state through landfall rather than either further strengthening or weakening. From landfall, it took a near identical NE path to a little W of Savannah. Per the archives at closest approach Hermine was at 31.9N, 82.0W..55 mi WSW of Sav and 989 mb/50 mph. (It was moving NE at 18 mph.) To compare, Idalia was at 32.2N, 81.7W or 40 mi W of Sav with 984 mb/70 mph. (It was moving a similar NE at 21 mph.) So, they were at a similar distance away at their closest but Idalia was noted to have 20 mph higher winds (70 vs 50). What's really strange is that Hermine produced 6 mph stronger winds than Idalia! From Hermine wiki: "Hermine weakened while crossing from Florida into Georgia, but still produced sustained winds of 45 mph at Savannah, with gusts to 58 mph." https://en.m.wikipedia.org/wiki/Hurricane_Hermine#:~:text=Hermine weakened while crossing from,(93 km%2Fh). Idalia's highest sustained/gust at Savannah were 6 mph lower with 39 sustained/gusts to 52. I remember clearly that Hermine was significantly stronger. And keep in mind that Idalia landfalled at 125 mph vs Hermine's only 80. I'm thankful but also amazed at the comparison. Any thoughts from anyone about this comparison?

I've had no power for 6 hours. About 1/3 of the area lost power. Otherwise, thank goodness we got pretty lucky compared to how bad I thought the winds might get based on earlier NHC forecasts. The highest official wind gust was near 52 mph and there were only a few near that high. But had those forecasts held, we likely would have had gusts into the 60s, which would have meant more trees down and a bigger mess. I was comparing Idalia with 2016's Hermine, which peaked at 80 mph/981 mb 5 hours before FL landfall near where Idalia hit. It went steady state through landfall rather than either further strengthening or weakening. From landfall, it took a near identical NE path to a little W of Savannah. Per the archives at closest approach Hermine was at 31.9N, 82.0W..55 mi WSW of Sav and 989 mb/50 mph. (It was moving NE at 18 mph.) To compare, Idalia was at 32.2N, 81.7W or 40 mi W of Sav with 984 mb/70 mph. (It was moving a similar NE at 21 mph.) So, they were at a similar distance away at their closest but Idalia was noted to have 20 mph higher winds (70 vs 50). What's really strange is that Hermine produced 6 mph stronger winds than Idalia! From Hermine wiki: "Hermine weakened while crossing from Florida into Georgia, but still produced sustained winds of 45 mph at Savannah, with gusts to 58 mph." https://en.m.wikipedia.org/wiki/Hurricane_Hermine#:~:text=Hermine weakened while crossing from,(93 km%2Fh). Idalia's highest sustained/gust at Savannah were 6 mph lower with 39 sustained/gusts to 52. I remember clearly that Hermine was significantly stronger. And keep in mind that Idalia landfalled at 125 mph vs Hermine's only 80. I'm thankful but also amazed at the comparison. Any thoughts from anyone about this comparison?

That was wild, the car lifting up! Those little tornadoes are sneaky and can pack a heck of a punch even though this was most likely "weak" on the scale. Fortunately no serious injuries despite the car damage.

We did too. My highest winds were before 5PM. I had earlier thought per models/NHC that 5PM was to be the start of the worst. I think the main reason is that it got to its closest point just after 5PM instead of the previously expected 8PM.

The perfect major storm that not only hit a sparsely populated area but also fortunately had an eyewall replacement going on just before landfall as opposed to the continued strengthening that some were expecting. But Perry, Madison, and Valdosta still had a big hit.

I think there have been at least a few.

PRELIMINARY LOCAL STORM REPORT NATIONAL WEATHER SERVICE CHARLESTON SC 253 PM EDT WED AUG 30 2023 .TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON .DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE. ..REMARKS.. 1222 PM TORNADO 1 NW GOOSE CREEK 32.99N 80.04W 08/30/2023 BERKELEY SC EMERGENCY MNGR EMERGENCY MANAGEMENT REPORTED THAT A CAR WAS FLIPPED OVER AT THE INTERSECTION OF CAMELOT DRIVE AND SOUTH GOOSE GREEK BLVD. VIDEO WAS USED TO CONFIRM THAT THE CAR WAS HIT BY A BRIEF, WEAK TORNADO. NO OTHER DAMAGE REPORTED.

I lost power an hour ago. My highest gusts have been ~45 mph. So, not bad vs what we were facing IF that were to end up being the worst. I was worried about gusts in the 60s, which would bring a lot more trees down.

So, the downgrade is 9 hours ahead of what the 5AM advisory had and 4+ hours ahead of what the 11AM advisory had.

Good to see although not surprising based on earlier trends. But right when downgrade occurred and after blinking on and off many times, I lost power (~20 min ago). I had a gust in the low 40s ~2 hours ago and a similar one recently, but nothing too bad so far. And it is moving more quickly than forecasted. As of 5PM NHC update, it was already due W of SAV (40 miles W) at 32.2N, 81.7W. That's nearly 3 hours ahead of what the 11AM NHC had as it had it due W of SAV not til 8PM (32.4N, 81.1W).

The 12Z UKMET still has that MDR TC that the Euro and other models have though it isn't as strong as the 0Z: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 84 HOURS FORECAST POSITION AT T+ 84 : 10.1N 20.2W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 03.09.2023 84 10.1N 20.2W 1009 28 1200UTC 03.09.2023 96 10.3N 22.8W 1009 25 0000UTC 04.09.2023 108 12.1N 26.6W 1009 26 1200UTC 04.09.2023 120 12.4N 30.5W 1008 27 0000UTC 05.09.2023 132 12.9N 34.2W 1008 29 1200UTC 05.09.2023 144 13.4N 38.2W 1007 31 0000UTC 06.09.2023 156 13.9N 41.0W 1006 33 1200UTC 06.09.2023 168 14.2N 44.3W 1004 38

Hopefully not. It appears that the center may be tracking inland of Savannah a decent amount, which would keep winds down somewhat vs how high they might have otherwise been. Combined with the quicker weakening vs NHC forecasts that I just posted about, that combination would be good news to keep winds down from how high it earlier appeared winds might get. I earlier thought outages would be widespread along with numerous trees down throughout the area. That may still end up being the case as winds are picking up and will get strong by late afternoon. But perhaps it won't be as bad as earlier feared.

Compared to the 5AM NHC forecast, it has weakened quite a bit more quickly than forecasted then. The 5AM had Idalia still with winds of 100 mph as of 2PM. But as of 1PM, winds were already down to 80. The 11AM had adjusted for this quicker weakening because it was already down to 90 then. This updated forecast had it weakening from 90 at 11AM to 75 at 8PM. But with it already down to 80 at 1PM, it appears that it is weakening even more quickly than the 11AM NHC forecast.

Some good news. Compared to the 5AM NHC forecast, it has weakened quite a bit more quickly than forecasted then. The 5AM had Idalia still with winds of 100 mph as of 2PM. But as of 1PM, winds were already down to 80. The 11AM had adjusted for this quicker weakening because it was already down to 90 then. This updated forecast had it weakening from 90 at 11AM to 75 at 8PM. But with it already down to 80 at 1PM, it appears that it is weakening even more quickly than the 11AM NHC forecast. Edit: down to 75 at 2PM vs the 11AM still having 75 at 8PM