GaWx

Does anyone have a feel for the risk to Jamaica for July 3rd? Relatives of mine have a cruise going there then and I haven’t had any time to look at progs. TIA

I still wonder about the true impact of the Hunga Tonga underwater eruption and the huge amount of water vapor emitted up into the stratosphere, which supposedly will linger for several more years.

Some of my relatives have a long ago planned cruise that starts over weekend from FL and goes to Yucatan/Caymans through 7/2. But then goes to Jamaica on 7/3, Bahamas 7/5, and then back to FL. I said all good thru 7/2 but Jamaica on 7/3 COULD get tricky and smaller chance of an issue in Bahamas+. Any other opinions would be appreciated. Does that sound about right? TIA

The 12Z GFS/ICON/CMC/Euro/UKMET/GEFS/GEPS look pretty similar to their respective earlier runs. Im still waiting to see if the ICON and especially UKMET are going to do more with this. The JMA fwiw is significantly stronger through the Caribbean with a strong TS in the W Car. The Euro ens mean looks a bit further SW with just a few either recurving off the SE or hitting FL. Many hit from Nicaragua N to the central US Gulf coast.

You’re 100% sure there won’t be El Niño in 2025-6? I’m not predicting one as I’m not even trying to predict 2025-6 this early. But I’m at least open to one then due to normal uncertainty. I read a paper I posted about that suggests a higher than normal chance of a multiyear El Niño later this decade due to the underwater Hunga Tonga volcanic eruption fwiw. But I’m not hanging my hat on that. Just being open minded. Also, arguably, 2023-4 Nino was only moderate based on RONI and MEI. Note that there was 1963-4 (mod Nino) followed by 1964-5 (weak Niña) followed by strong Nino (1965-6). In addition, though all were weak there was 2004-5 (Nino), 2005-6 (Niña), and 2006-7 (Nino). Also consider these two groups from before 1950 per Eric Webb: -1902-3 (strong Nino), 1903-4 (weak Nina), 1904-5 (moderate Nino) -1923-4 (mod Nino), 1924-5 (mod Niña), 1925-6 (strong Nino)

I agree that having an actual TD and especially TS first exist before the Lesser Antilles would increase the chance of a H in the Caribbean though even that would still be far from a guarantee of course and not even likely due to the frequency of struggle in the E Car. The Euro having it not only not struggle there and instead steadily strengthen there should be taken with a huge grain at this early stage imho, especially with the GFS doing the opposite.

Thanks, Charlie. Check these hourlies out from last evening: 7PM AUGUSTA-BUSH MOSUNNY 99 49 18 SW13 29.72 HX 96 TC 37 AUGUSTA-DANIEL MOSUNNY 99 52 20 SW8 29.75F HX 96 TC 37 8PM AUGUSTA-BUSH FAIR 89 72 56 SE12 29.74R HX 96 TC 32 6HR MIN TEMP: 89; 6HR MAX TEMP: 103; AUGUSTA-DANIEL FAIR 97 53 22 SW9 29.77R HX 94 TC 36 6HR MIN TEMP: 97; 6HR MAX TEMP: 103; 9PM AUGUSTA-BUSH CLEAR 88 68 51 S15G29 29.76R HX 91 TC 31 AUGUSTA-DANIEL CLEAR 90 73 57 S10G20 29.78R HX 98 TC 32 Note that from 7PM to 8PM Bush’s winds shifted from that very dry/hot SW direction to a much cooler/higher dewpoint (10 cooler/23 higher!) SE direction. But Daniel didn’t shift to SE and thus hardly changed. But then Daniel had the big change from 8PM to 9PM after their winds finally shifted away from the hot/dry SW winds.

1. The 0Z UKMET maps just came out. Not only do they not have a TC as I already knew from the text output issued 2+ hours earlier, they don’t even have a closed low, similar to prior runs! Keep in mind that this is one of the better models. 2. OTOH, the 0Z Euro ens is about as active as the quite active 12Z. What a battle!

The 0Z Euro still has a TC on a similar path to the 12Z but it isn’t as strong as the 12Z had, especially in the W Caribbean, where the 12Z had at least a cat 3. This is at most a cat 1 there. Regardless, it would still be pretty amazing in early July to have a TC not only survive the Caribbean but also strengthen into a (near) H as it crosses it!

The UKMET (0Z) still doesn’t have a TC from this. The 0Z GEFS remains pretty active.

With an open mind due to curiosity, I did my own analysis of objective ENSO/Solar/QBO data back to 1958: 1) First of all, is La Niña/W QBO really extra favorable for major SSWs? La Niña/W: 5 major SSWs (2/26/99, 3/20/00, 1/24/09, 1/5/21, 2/16/23) La Niña/E: 5 major SSWs (1/20/71, 2/24/84, 2/11/01, 1/21/06, 2/12/18) El Nino/W: 5 major SSWs (1/30/58, 12/8/87, 3/14/88, 2/24/07, 1/2/19) El Nino/E: 12 major SSWs (11/30/58, 12/16/65, 2/23/66, 11/29/68, 1/9/77, 2/29/80, 1/23/87, 2/9/10, 3/24/10, 1/16/24, 2/18/24, 3/4/24) Thus, I see no evidence that La Niña/W QBO is extra favorable for major SSWs. The only one of the four combos analyzed that clearly is extra favorable for major SSWs is El Niño/E QBO, like we had last winter and hopefully will again during the winter of 2025-6. 2) Secondly, were the five La Niña/W major SSWs mainly near solar max? -Feb 1999: sunspots 98 and ~halfway between min and max. This, I consider this neutral solar. -Mar 2000: sunspots 218/1 yr pre solar max -Jan 2009: sunspots 1/solar min -Jan 2021: sunspots 10/1.5 yr post solar min -Feb 2023: sunspots 111/2 yrs pre solar max So, there was a mix and the avg sunspots of the 5 was 88, which is near longterm mean. Thus, I see no evidence of increased chance of major SSWs when La Niña/W is near solar max. To be clear, this analysis isn’t suggesting having a major SSW this winter is unlikely. Rather, it suggests it isn’t likely either and is instead only about a coin flip even with solar max. There have been 8 La Niña West winters since 1957-8: 1971-2, 1975-6, 1999-00, 2008-9, 2010-1, 2016-7, 2020-1, and 2022-3. So, 4 of these 8 (50%) La Niña/W winters had a major SSW. Out of curiosity, I decided to calculate the % of El Niño/E winters with at least one major SSW. These are the El Niño/E winters since 1957-8: 1958-9, 1965-6, 1968-9, 1976-7, 1979-80, 1986-7, 1991-2, 2009-10, 2014-5, and 2023-4. So, of these 10 El Niño/E winters, a whopping 8 (80%) had at least one major SSW! And the ratio of 12 majors during these 10 winters is even more impressive thanks to 3 of the 10 winters having 2+ of them! Thus, that’s even more reason to hope for El Niño next winter. —————————————— Edit: What % of La Niña/E winters had at least one major SSW? These were the 10 La Niña/E winters since 1957-8: 1970-1, 1974-5, 1983-4, 1995-6, 2000-1, 2005-6, 2007-8, 2011-2, 2017-8, and 2021-2. So, like for La Niña/W, half (5 of 10) of those had an SSW. What % of El Niño/W winters had 1+ SSWs? These were the 9 El Niño/W winters: 1957-8, 1963-4, 1977-8, 1982-3, 1987-8, 1994-5, 2006-7, 2015-6, and 2018-9. Out of the 9, 4 (44%) had at least one major SSW. ———————- Data sources: ENSO https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php Solar (monthly sunspots): https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt QBO (30 mb): https://psl.noaa.gov/data/correlation/qbo.data Major SSW events (plus I added 2023 and 2024 events) https://en.m.wikipedia.org/wiki/Sudden_stratospheric_warming @snowman19

Alright Ed, you can have at it if you want as it is now Invest 95L: https://rammb-data.cira.colostate.edu/tc_realtime/storm.asp?storm_identifier=al952024

The NWS, which wasn’t quite as hot nor nearly as dry as the HRRR, did better than the HRRR. Verification of yesterday’s 6Z HRRR prog for temperature/dewpoint at 19Z/3PM EDT today: Richmond, VA: HRRR 103/52 vs actual 99/68 Raleigh, NC: HRRR 100/61 vs actual 96/66 Charlotte, NC: HRRR 102/48 vs actual 98/63 Columbia, SC: HRRR 103/58 vs actual 100/60 Florence, SC: HRRR 99/64 vs actual 94/73 Atlanta, GA: HRRR 101/45 vs actual 95/55 Augusta, GA: HRRR 103/46 vs actual 99/52 Brunswick, GA: HRRR 96/66 vs actual 91/78 Summary for 8 cities: -HRRR was too hot for all 8 with avg miss of +4.4 with range of +3 (Columbia) to +6 (Atlanta) -HRRR was too dry for all 8 with avg dewpoint miss of -9.4 with range -2 (Columbia) to -16 (Richmond) 3PM data sources: GA https://kamala.cod.edu/ga/latest.asus42.FFC.KFFC.html SC https://kamala.cod.edu/sc/latest.asus42.CAE.KCAE.html NC https://kamala.cod.edu/nc/latest.asus42.RAH.KRAH.html VA https://kamala.cod.edu/va/latest.asus41.AKQ.KAKQ.html

TW SW of CV: Once past the Lesser Antilles the 12Z Euro ensemble tracks most concentrated toward Cuba to Nicaragua corridor followed by good number hitting MX/TX/W LA while minority threaten PR to SE US with only very few recurving offshore the E US coast

12Z Euro ensemble is its most active run yet at Lesser Antilles ~July 1st

951 mb at 240 coming onto the coast of the Yucatan!

For TW SW of CV: 12Z Euro is much stronger as it has a TS on 7/1 in the Lesser Antilles and a hurricane later on in the Caribbean! I’m pretty sure we’ll need a separate thread for this soon. @Ed, snow and hurricane fanwant to start it?

12Z runs for TW SW of CV Islands: -GFS/CMC TS+ Lesser Antilles ~7/1; so CMC stronger than 0Z and similar to yesterday’s 12Z -ICON stronger low than 0Z/borderline TD? -UKMET still no TC through 168 -GEFS still rather active Eastern Tropical Atlantic: A tropical wave located a few hundred miles southwest of the Cabo Verde Islands is producing disorganized showers and thunderstorms. Some development is possible during the next several days, and a tropical depression could form over the tropical Atlantic by the end of the week or this weekend while the system moves westward at 15 to 20 mph. * Formation chance through 48 hours...low...near 10 percent. * Formation chance through 7 days...medium...40 percent.

Check this out for something fascinating at Augusta, GA (Bush): -noon was 93 with a dewpoint of 76 on a SE wind at 9 -1PM was 99 with a dewpoint way down at 58 on a SW wind at 13 gusting to 22!! That’s a heck of a boundary, a dry line of sorts that went through Augusta last hour! And it came in on SW winds!

Check this out CC and others for something fascinating at Augusta, GA (Bush): -noon was 93 with a dewpoint of 76 on a SE wind at 9 -1PM was 99 with a dewpoint way down at 58 on a SW wind at 13 gusting to 22!! That’s a heck of a boundary that went through there last hour, a dry line of sorts! And the drier air came in on SW winds!

But there’s no official downtown Atlanta station to see how hot downtown will be. So, we’ll never know what their actual will be. There hasn’t been an official downtown station there in many decades.

Regarding this map with forecasted highs: -Atlanta’s official station is the airport, not downtown. It is near the perimeter. Unfortunately, downtown doesn’t have an official station, which would be where the UHI center is typically strongest obviously. So, if the official Atlanta high were to be 98 as this map is forecasting, downtown could easily be over 100 if the winds are light enough. We’ll never know. -Atlanta has higher elevation than Dalton/Thomaston by 300 feet, Rome/Athens/Madison by 400 feet, Macon/Sandersville by 600 ft, and Columbus/Dublin by 800 ft.

For wave in E Atlantic, main 0Z Models: -GFS is by far its strongest run yet as it has a 975-7 mb H hitting the Windward Islands on July 1st, which then weakens and later dissipates in the Caribbean -CMC just has a weak low vs 12Z’s TS -ICON just has a weak low similar to 12Z -UKMET doesn’t have a TC just like the 12Z -GEFS is about as active as the 18Z. These last two runs are the strongest runs yet at the Lesser Antilles July 1-2 -0Z Euro is a bit more active than prior run with a defined LLC E of the Lesser Antilles though it is still a weak low (doesn’t look strong enough for TD imo) and then it dissipates as it enters the Caribbean TWO upped from 20% to 30% thru day 7: 2. Eastern Tropical Atlantic: A tropical wave centered a few hundred miles south-southwest of the Cabo Verde Islands is producing disorganized showers and thunderstorms. Some slow development of this system is possible late this week into early next week while it moves generally westward across the central and western tropical Atlantic at 15 to 20 mph. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 7 days...low...30 percent.

The HRRR maps being analyzed are for 3PM tomorrow (6/26), not today. I’ll compare them after then to see how they did. But indeed, low dewpoints and high heat were there today as you said. Will dewpoints be low enough and temps high enough tomorrow for the comparison? We’ll see!

1. The SE Caribbean tropical wave has just been designated as Invest 94L fwiw. 2. The 12Z GEFS/GEPS have a rather strong signal for a TC impacting the Lesser Antilles ~7/1-3. 3. The 12Z Euro has no TC unlike the prior two runs. Edit: But 12Z EPS is most active run yet.