GaWx

I have found the GEFS and Euro Ens to be the best for MJO predictions and the CFS and BoM (which were often way too amplified last winter) to be the worst. JMA/CMC in between/harder to tell since don’t go out as far. I know JB likes to look at the JMA as gold standard for MJO forecasting, which has bitten him a number of times.

For NYC during La Niña (which will likely verify on RONI basis), the Dec snowfall was a very good indicator for the rest of the season’s snowfall there as @bluewaveand/or @donsutherland1showed. So, it will be quite interesting to see where their Dec snowfall ends up.

TD 19 has become TS Sara: devastating rainfall in N Honduras and nearby is the main danger: Tropical Storm Sara Intermediate Advisory Number 4A NWS National Hurricane Center Miami FL AL192024 100 PM EST Thu Nov 14 2024 ...DEPRESSION STRENGTHENS INTO TROPICAL STORM SARA... ...LIFE-THREATENING AND POTENTIALLY CATASTROPHIC FLASH FLOODING AND MUDSLIDES EXPECTED IN HONDURAS THROUGH THE WEEKEND... SUMMARY OF 100 PM EST...1800 UTC...INFORMATION ---------------------------------------------- LOCATION...15.7N 82.9W ABOUT 205 MI...330 KM ESE OF ISLA GUANAJA HONDURAS ABOUT 50 MI...85 KM NE OF CABO GRACIAS A DIOS ON NIC/HON BORDER MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...W OR 265 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES DISCUSSION AND OUTLOOK ---------------------- At 100 PM EST (1800 UTC), the center of Tropical Storm Sara was located by Air Force Reserve reconnaissance aircraft near latitude 15.7 North, longitude 82.9 West. The system is moving toward the west near 12 mph (19 km/h). This motion should continue through today, bringing the center near the coast of eastern Honduras. The system is expected to meander near the northern coast of Honduras late Friday and through the weekend. Data from the Air Force Reserve aircraft indicate that the maximum sustained winds have increased to near 40 mph (65 km/h) with higher gusts. Some strengthening is possible, if the system remains over water. Tropical-storm-force winds extend outward up to 70 miles (115 km) from the center, mainly in the northern semicircle. The estimated minimum central pressure based on dropsonde data is 999 mb (29.50 inches). RAINFALL: Through early next week, rainfall amounts of 10 to 20 inches with isolated storm totals around 30 inches area expected over northern Honduras. This rainfall will lead to widespread areas of life-threatening and potentially catastrophic flash flooding and mudslides, especially along and near the Sierra La Esperanza. Elsewhere across the rest of Honduras, Belize, El Salvador, eastern Guatemala, and western Nicaragua, Tropical Storm Sara is expected to produce 5 to 10 inches of rain with localized totals around 15 inches through early next week. This will result in areas of flash flooding, perhaps significant, along with the potential of mudslides.

Here’s the latest chart showing the Euro ensemble mean’s forecasted US pop weighted HDD (on left)(green is normal): the 0Z (purple) lost 5 HDD vs yesterday’s 12Z (yellow), which helped to cause NG prices to drop moderately (now down ~4% vs yesterday)(edit: ended ~6% down at close). As Chuck knows, NG price trends are often a good barometer of changing trends of the forecasted upcoming E US wx (especially in the E US out 7-14 days): coldest days of this period still look to be 11/23-6:

Here’s the projected rainfall for Honduras, which I’m thinking will end up the big news story from this storm: For comparison, here is the estimated rainfall from the devastating Eta in 2020, which caused horrible river flooding in Honduras and looks pretty similar to the current storm

Potentially devastating flooding for N Honduras similar to Eta/Iota of 2020 and Mitch of 1998 due to extremely slow movement: dire situation there BULLETIN Tropical Depression Nineteen Advisory Number 4 NWS National Hurricane Center Miami FL AL192024 1000 AM EST Thu Nov 14 2024 ...LIFE-THREATENING AND POTENTIALLY CATASTROPHIC FLASH FLOODING AND MUDSLIDES EXPECTED IN HONDURAS THROUGH THE WEEKEND... SUMMARY OF 1000 AM EST...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...15.7N 82.6W ABOUT 225 MI...365 KM ESE OF ISLA GUANAJA HONDURAS ABOUT 65 MI...100 KM NE OF CABO GRACIAS A DIOS ON NIC/HON BORDER MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...W OR 265 DEGREES AT 14 MPH...22 KM/H MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Honduras has discontinued the Hurricane Watch for Honduras and the Bay Islands. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * The northern coast of Honduras form Punta Sal eastward to the Honduras/Nicaragua Border * The Bay Islands of Honduras A Tropical Storm Watch is in effect for... * The northeastern coast of Nicaragua from Puerto Cabezas northward to the Honduras/Nicaragua Border A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests elsewhere in Honduras, Guatemala, Belize and the Yucatan Peninsula should monitor the progress of this system. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 1000 AM EST (1500 UTC), the center of Tropical Depression Nineteen was located near latitude 15.7 North, longitude 82.6 West. The depression is moving toward the west near 14 mph (22 km/h). This motion should continue through today, bringing the center near the coast of eastern Honduras. The system is expected to meander near the northern coast of Honduras late Friday and through the weekend. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Some strengthening is forecast and the system is forecast to become a tropical storm later today. The estimated minimum central pressure is 1004 mb (29.65 inches). RAINFALL: Through early next week, rainfall amounts of 10 to 20 inches with isolated storm totals around 30 inches area expected over northern Honduras. This rainfall will lead to widespread areas of life-threatening and potentially catastrophic flash flooding and mudslides, especially along and near the Sierra La Esperanza. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 15.7N 82.6W 30 KT 35 MPH 12H 15/0000Z 15.7N 83.7W 35 KT 40 MPH 24H 15/1200Z 15.9N 84.9W 40 KT 45 MPH...NEAR THE COAST 36H 16/0000Z 15.9N 85.4W 40 KT 45 MPH...NEAR THE COAST 48H 16/1200Z 15.9N 85.8W 40 KT 45 MPH...NEAR THE COAST 60H 17/0000Z 16.0N 86.2W 45 KT 50 MPH...NEAR THE COAST 72H 17/1200Z 16.2N 87.0W 45 KT 50 MPH...OVER WATER 96H 18/1200Z 18.0N 89.6W 30 KT 35 MPH...INLAND 120H 19/1200Z 21.7N 91.6W 30 KT 35 MPH...OVER WATER $$ Forecaster Kelly

Mine too. I got ~1,000% of my climo mean liquid equivalent of wintry precip (all from one storm in early 1/2018), which is the largest since 1921-2! The one in late 1/1922 was the predecessor to the NE US’ Knickerbocker Storm. The snow/sleet combo portion of 1/2018 was the heaviest since the great 12/1989 coastal pre-Christmas near blizzard.

These 12Z model runs all have 20”+ of rainfall over part of N Honduras: GFS, Euro, Icon, and CMC. Add to that the 6Z Euro-AIFS. This is the kind of rainfall that can lead to another flooding disaster, especially if the track is a little further south. This kind of resembles the Mitch track, which also caused a flooding disaster there and nearby and resulted in 11K++ deaths. FL would likely only be a minor concern in comparison:

https://s2s.worldclimateservice.com/climatepanel/ Then click on PDO, which is 2nd graph down on right.

Is OISST on crack? This shows it already barely into the positive! while the cool biased CDAS is still down near -0.7 (huge discrepancy): and the slightly warm biased CRW is still down at -0.3: -Of course the equivalent RONI is still likely sub -0.5. - This all gives me hope that the last 3 CANSIPS depictions of Modoki El Niño by next summer aren’t on crack.

In 2020 Eta and Iota lead to horrific river based flooding in especially Honduras and Guatemala even though those storms were moving at a halfway decent pace. The damage included very heavy ag losses like coffee. The coffee crop in that area of Central America (especially in W Honduras, Guatemala and N Nicaragua) is one of the most concentrated in the world outside of Minas Gerais (in Brazil). Even though they were major hurricanes, the damage/casualties from wind and surge were nothing like that from the flooding. More flooding would be awful. Things like this only cause increases in folks trying to migrate to the US and other better locations.

Indeed, that’s a rise of ~1.3 from Oct 10th’s ~~-4 to -4.1 on a NOAA basis. So, now it is likely ~~-2.7 to -2.8 on a NOAA basis.

That’s why I’m implying more than the normal amount of caution is recommended to any folks who might be tempted to put large weight on the MJO phases while the W Pacific marine heatwave persists. All things being equal, I’d think that a colder phase would still be preferred, however.

Even when the MJO isn’t technically in the warmer phases, doesn’t the W Pacific marine heatwave support the tendency toward E US warmth/stronger SE ridge often negating the cold tendencies of the colder MJO phases to an extent? Also, I’ll point out my detailed studies of large samples which have shown that lower amplitude MJO phases have tended to be colder than high amp. (not nearly always obviously but rather in the means). I’m talking with no lag. Perhaps it has something to do with less tropical forcing when the MJO phase is weaker. Then again though, the W Pac marine heatwave may tend to negate some of the cold tendencies of weak MJO, too, as these studies were based on data back to the mid 1970s.

GEFS through 0Z run continue to look scarey for W FL, especially Tampa south and centered on Ft. Myers. If this hits the Conus as a H, it would tie 1886, 1985, and 2020 for the alltime record of 6 H hits! What an awful season for the US. The weak La Niña on a RONI basis showed once again why weak Niña has averaged the most dangerous for the US. Hoping for El Niño next year.

Euro ens mean through day 14 with pop. wted US HDDs on left (0Z yellow, 12Z purple): BN HDDs 11/16-20, NN 11/21-26; compare this to the last time I posted this, when the highest any day’s HDD got was slightly BN and with most days with solidly BN HDDs.

In terms of RONI, 1978 ASO was at -0.19 compared to 2024’s -0.76. So RONI is much lower in 2024. Also, 2024’s MEI, which was already down to -0.7 in JA, is much lower than 1978, which was still up at +.0.5 in JA and never got lower than +0.2. So, in terms of RONI and MEI, 2024 and 1978 aren’t close.

The latest Euro Weeklies for 11/18-24 show this well: 4 x climo (~4-5) closer to normal ACE of a month to 1.5 months earlier:

Has 3.4 already hit its low? The following 4 show that we’re now a good bit warmer than the ~Sep 20th low: OISST: CRW: CDAS: Buoys: significantly warmer than coolest, especially 130-165W: Supporting this idea that the coldest may be done is the OHC:

The image below is the Nov 10th, 2023, Euro Weeklies SPV prog through Dec 25th, whose mean had a strong SPV and didn’t have it going weaker than normal til mid Dec. Looking back at the many I saved, they all had a strong SPV for Nov. Then look what happened with the 11/22/23 run’s mean, which while still having a strong SPV in Nov suddenly had a weak SPV for 12/6/23 through 1/6/24. The strong Nov SPV verified quite well. Dec actually ended up with a fairly weak SPV much of the month (so not too far off) but with no major SSW: Here’s actual for Nov-Dec 2023: Strong Nov SPV (well predicted) and a bit weaker than the ~32 climo wind in Dec with no SSW (verified pretty well with actual avg wind speed of ~27 vs many EW runs, including the one above, at ~25): Yesterday’s EW mean has a near normal rest of Nov SPV averaging ~31, which is much weaker than Nov 11-30, 2023’s ~38. Then it has a very slightly BN Dec of ~30 (vs climo of ~32). If this EW were to verify well, we’d end up with a significantly weaker SPV in Nov and somewhat stronger in Dec in 2024 vs 2023:

-0Z ICON and CMC are threats to FL 0Z UKMET: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 78 HOURS FORECAST POSITION AT T+ 78 : 16.7N 83.0W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 15.11.2024 84 16.6N 83.9W 1003 25 0000UTC 16.11.2024 96 16.4N 84.0W 1001 26 1200UTC 16.11.2024 108 15.7N 83.4W 1001 27 0000UTC 17.11.2024 120 15.3N 82.9W 1001 29 1200UTC 17.11.2024 132 15.4N 83.4W 1002 29 0000UTC 18.11.2024 144 16.3N 84.6W 1002 31 1200UTC 18.11.2024 156 17.8N 86.1W 1001 34 0000UTC 19.11.2024 168 20.7N 86.8W 999 38

We’ll probably get a RONI 3 month low point of sub -0.8.

12Z UKMET: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 120 HOURS FORECAST POSITION AT T+120 : 14.4N 81.1W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 16.11.2024 120 14.4N 81.1W 1002 27 0000UTC 17.11.2024 132 14.3N 80.6W 1001 31 1200UTC 17.11.2024 144 13.9N 80.2W 1001 32 0000UTC 18.11.2024 156 14.3N 80.4W 1000 33 1200UTC 18.11.2024 168 14.8N 80.9W 999 33

Possibly headed well into the 160s due to next potential W Car TC.

159.8