GaWx

That’s the nature of a solid +PNA as you know, especially without an accompanying -EPO. There has been a pretty strong +EPO in recent days. Often the coldest anomalies on average tend to be further SE with it often above normal in much of Canada. As the Euro Weeklies show, I also expect a warmup after the next 2 weeks. But, in the meantime, as mentioned the E 1/4 of the US is overall progged to have its coldest 10/27-11/9 since 2012 with coldest anomalies centered southern Mid-Atlantic states and SE US. Per the EW, a warmup follows but mainly to near normal rather than AN with only week 4 AN and it only slightly AN.

There are 3 Atlantic basin hurricanes on record on this date or later that were cat 5 and they had these lowest pressures/highest sustained winds: -Mitch of 1998: Oct 26-28; 905 mb/180 mph; but landfall was way down at 80 mph on Honduras. The extreme rainfall though was what made it so deadly. -Hattie of 1961: Oct 31; 914 mb/165 mph; it weakened slightly at landfall in Belize to 915 mb/150 mph (cat 4) -Cuba hurricane of 1932: Nov 5-8; 915 mb/175 mph; but it weakened some before hitting land as it was 150/cat 4 on landfall The latest on record cat 5 landfall was on Cuba on Oct 19 (in 1924) near its peak intensity of 165 mph. So, IF this were to hit Jamaica as a cat 5, it would become the latest on record to make landfall anywhere by 9 days.

This is very sad and terrifying to see knowing that Jamaica is in the crosshairs of this monster. Hopefully something unexpected will change things at least a little bit for the better before landfall. Any weakening would be quite welcome obviously.

It isn’t just upwelling that cools the waters at or near where a hurricane crosses: it also cools due to the conservation of energy (potential energy from warm water transitions to kinetic (wind) energy of the storm/heat engine), cooling from raindrops (I assume this factor is relatively minor), and cooling from cloudcover blocking the sun: Hurricanes cool the ocean by acting like "heat engines" that transfer heat from the ocean surface to the atmosphere through evaporation. Cooling is also caused by upwelling of cold water from below due to the suction effect of the low-pressure center of the storm. Additional cooling may come from cold water from raindrops that remain on the ocean surface for a time. Cloud cover may also play a role in cooling the ocean by shielding the ocean surface from direct sunlight before and slightly after the storm passage. All these effects can combine to produce a dramatic drop in sea surface temperature over a large area in just a few days. https://earthobservatory.nasa.gov/images/6223/passing-of-hurricanes-cools-entire-gulf#:~:text=Hurricanes cool the ocean by,pressure center of the storm

BULLETIN Hurricane Melissa Intermediate Advisory Number 22A NWS National Hurricane Center Miami FL AL132025 800 PM EDT Sun Oct 26 2025 ...LIFE-THREATENING AND CATASTROPHIC FLASH FLOODING AND LANDSLIDES EXPECTED IN PORTIONS OF JAMAICA AND SOUTHERN HISPANIOLA THROUGH MIDWEEK WITH HURRICANE FORCE WINDS LIKELY TO BEGIN TOMORROW... SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION ---------------------------------------------- LOCATION...16.4N 77.3W ABOUT 115 MI...185 KM SSW OF KINGSTON JAMAICA ABOUT 295 MI...475 KM SSW OF GUANTANAMO CUBA MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...933 MB...27.55 INCHES

Today’s Euro Weeklies out 6 weeks for E US: - Coldest 1st 2 weeks of any run for that period (10/27-11/9) thanks to a combo of an impressive +PNA and impressive ascending -NAO, which should it verify closely would be coldest for E US overall since the similarly chilly Oct 27-Nov 9 in 2012. For those curious, that period in 2012 actually had a mean near opposite weak -PNA as well as a similarly strong -NAO and weak -AO. It had a +EPO like we have now. It had for the MJO a moderate 2, mod 3, and ended with weak 4/5. - No long period of mild in sight with weeks 3, 5, and 6 NN and week 4 only barely AN

Today’s Euro Weeklies out 6 weeks for E US: - Coldest 1st 2 weeks of any run (see below) for that period thanks to a combo of an impressive +PNA and impressive ascending -NAO, which should it verify closely would be coldest for E US overall since the similarly chilly 2012 for Oct 27-Nov 9. For those curious, that period in 2012 actually had a mean near opposite weak -PNA as well as a similarly strong -NAO and weak -AO. Edit: it had a +EPO like we have now. It had for MJO moderate 2, mod 3, and ended with weak 4/5. - No long period of mild in sight with weeks 3, 5, and 6 NN and week 4 only barely AN Week 1 (Oct 27-Nov 2): Week 2 (Nov 3-9):

WTNT43 KNHC 262100 TCDAT3 Hurricane Melissa Discussion Number 22 NWS National Hurricane Center Miami FL AL132025 500 PM EDT Sun Oct 26 2025 After an earlier pause in intensification, this afternoon's Air Force Reserve reconnaissance mission has found Melissa intensifying again. The minimum pressure has fallen 12 mb from this morning NOAA-P3 mission, with the last dropsonde indicating a minimum pressure of 941 mb, and the plane reported a shrinking eyewall down to 6 n mi in diameter. In addition to the low pressure, the satellite presentation of Melissa remains very impressive, with 1-minute visible satellite images from a GOES-19 meso-sector showing a very clear eye with a stadium effect. The eye temperature on water vapor imagery has continued to warm, while the thick ring of eyewall cloud tops remains between -75 to -80 C around the eye. The presentation of Melissa on radar reflectivity from Kingston, Jamaica has also improved, though there still appear to be hints of a moat forming around the inner eyewall, though without an obvious secondary eyewall formation yet. Subjective Dvorak CI-numbers from both SAB and TAFB were T7.0/140 kt, with objective satellite estimates between 132-143 kt. However, Melissa's peak winds from the last couple of recon missions have been lagging the satellite-based estimates. The last fix had peak 700 mb flight level winds of only 129 kt, but a dropsonde launched in the north eyewall also reported a 500 m layer average of 142 kt, with an earlier dropsonde in the NE eyewall with a surface wind gust of 131 kt. This data is enough to raise the maximum sustained winds of 125 kt, and given the satellite presentation, this could be conservative. Melissa continues to move slowly westward, estimated at 270/4 kt. The hurricane has been moving a little faster to the west today, and this motion will likely continue for another 12-18 hours while the narrow mid-level ridge to the north remains in place. Soon, a short-wave trough will be moving into the SE United States, and this feature should create a weakness that Melissa will turn sharply northeast into, as it gradually accelerates. The track guidance has shifted a little westward again this cycle, and the NHC track forecast was nudged a little west again, but still shows landfall on Tuesday morning along the south coast of Jamaica. There remain some timing differences thereafter, but a second landfall is anticipated along the southeastern Cuba coast by Tuesday night or early Wednesday morning. As Melissa then accelerates into the southwestern Atlantic, it will move through the Bahamas and potentially approach Bermuda by the day 4-5 time frame, with a reinforcing trough helping to kick it farther out to sea. The latest NHC track forecast is a little west in the first 24-60 h, but falls back near the previous forecast track thereafter. The track is roughly a blend of the reliable HFIP Corrected Consensus Approach (HCCA) and Google Deep Mind ensemble mean (GDMI). Now that Melissa is intensifying again, it seems more clear that the earlier pause in intensification was a temporary oscillation, and the hurricane now appears poised to intensify more in the short-term. The latest NHC intensity forecast shows a little more intensification in 12 h, but continues to show a peak intensity of 140 kt, which is supported by HAFS-B which shows landfall of Melissa as a catastrophic Category 5 hurricane. The Google DeepMind ensemble members also continue to indicate this peak, with now 48/50 members reaching this lofty intensity. However, inner-core processes like ERCs could occur at any time, and the current small eye of Melissa likely suggests an ERC could begin in the next 24 hours or so, though it is very difficult to predict these occurrences with much skill. After landfall in Jamaica, Melissa will likely weaken some due to the interaction with that Island's high terrain, but it is still expected to be a major hurricane when crossing the Cuba coastline on Tuesday night. After emerging into the southwestern Atlantic Ocean, increasing vertical wind shear should continue gradual weakening through the end of the forecast, with the possibility that Melissa could start extratropical transition by day 5. The NHC intensity forecast continues to be on the high side of the guidance, but falls closer to the HCCA and IVCN aids towards the end of the forecast period. ———— Monday. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 16.4N 77.2W 125 KT 145 MPH 12H 27/0600Z 16.4N 77.7W 135 KT 155 MPH 24H 27/1800Z 16.6N 78.2W 140 KT 160 MPH 36H 28/0600Z 17.2N 78.2W 140 KT 160 MPH 48H 28/1800Z 18.4N 77.5W 115 KT 130 MPH...INLAND OVER JAMAICA 60H 29/0600Z 20.0N 76.1W 105 KT 120 MPH...ON THE SE CUBA COAST 72H 29/1800Z 22.1N 74.4W 90 KT 105 MPH...OVER WATER 96H 30/1800Z 28.0N 69.5W 80 KT 90 MPH 120H 31/1800Z 37.0N 60.0W 70 KT 80 MPH $$ Forecaster Papin

WTNT33 KNHC 262055 TCPAT3 BULLETIN Hurricane Melissa Advisory Number 22 NWS National Hurricane Center Miami FL AL132025 500 PM EDT Sun Oct 26 2025 ...HURRICANE MELISSA RESUMES INTENSIFYING... ...LIFE-THREATENING AND CATASTROPHIC FLASH FLOODING AND LANDSLIDES EXPECTED IN PORTIONS OF JAMAICA AND SOUTHERN HISPANIOLA THROUGH MIDWEEK WITH HURRICANE FORCE WINDS LIKELY TO BEGIN TOMORROW... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...16.4N 77.2W ABOUT 115 MI...185 KM SSW OF KINGSTON JAMAICA ABOUT 295 MI...470 KM SSW OF GUANTANAMO CUBA MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...941 MB...27.79 INCHES

Today’s Euro Weeklies 10 mb zonal wind update fwiw:

60 knot increase from 5AM EDT Saturday’s 60 knots to 5AM today’s 120 knots!

Yeah, it was first at 10:54AM. All of it was later vs average release time.

That wasn’t released til 10:56 AM EDT. That’s very late for the 11AM. And discussion still wasn’t out yet. It wasn’t released til 10:59AM!

There was only 39 ACE through Sept 16th. There has been 67 ACE Sept 17th through 12Z today with likely 20+ more to come from Melissa, alone. This heavy late season vs earlier has been more common in recent years, especially during La Niña.

BULLETIN Hurricane Melissa Intermediate Advisory Number 20A NWS National Hurricane Center Miami FL AL132025 800 AM EDT Sun Oct 26 2025 ...NOAA HURRICANE HUNTERS SAMPLING MELISSA... ...LIFE-THREATENING AND CATASTROPHIC FLASH FLOODING AND LANDSLIDES EXPECTED IN PORTIONS OF JAMAICA AND SOUTHERN HISPANIOLA THROUGH MIDWEEK... SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...16.3N 76.4W ABOUT 120 MI...195 KM SSE OF KINGSTON JAMAICA ABOUT 280 MI...450 KM SSW OF GUANTANAMO CUBA MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...952 MB...28.12 INCHES Maximum sustained winds are near 140 mph (220 km/h) with higher gusts. Melissa is a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Further rapid intensification is expected through tonight, followed by fluctuations in intensity. Melissa is expected to be a major hurricane when making landfall in Jamaica Monday night or Tuesday morning and southeastern Cuba late Tuesday. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 175 miles (280 km). The minimum central pressure estimated by aircraft dropsonde data is 952 mb (28.12 inches).

This will be a great test to see how much cooling of the surface there is by 10/29. Here was the SST map as of 10/24: note the large area of 30-31C surrounding Jamaica, which is the warmest in the Atlantic basin:

It will cool the water at least slowly because it’s taking the potential energy from the warm ocean and converting it into kinetic energy (its a heat engine). That’s related to tropical cyclones redistributing heat to higher latitudes. That’s in addition to any cooling of the surface from upwelling. I believe these are two separate processes.

Lowest SLP on record Jamaica 958 Charlie followed by 960 Gilbert.

18z Best Track up to 75kt. AL, 13, 2025102518, , BEST, 0, 165N, 752W 75, 976,HU

12Z Euro: goes back to an extent to the pre 0Z/6Z runs by being a bit further S of Jamaica thus helping it to get stronger (962) and thus it hits Jamaica at 971 instead of 986-8. It then goes back to a NE move over Jamaica and exits at 977 vs 992 of 0Z/6Z. As a result, the 20” line goes back further W to center of Jamaica.

UKMET has been even worse with a number of runs early on hitting Nicaragua and with it then correcting NE but only slowly. This issue was likely mainly due to it having it too weak. It is such a hot or miss model as it was stellar/the best with Imelda as well with Ian among others.

12Z GFS is the furthest west run yet with it going NNE over Kingston at 969 while strengthening during the 6 hour crossover. Kingston gets 35” But otoh, SW Haiti gets way less than prior runs gave.

Josh is on his way to Jamaica:

Not yet: BULLETIN Tropical Storm Melissa Advisory Number 17 NWS National Hurricane Center Miami FL AL132025 1100 AM EDT Sat Oct 25 2025 ...MELISSA NEAR HURRICANE STRENGTH AND FORECAST TO RAPIDLY INTENSIFY THIS WEEKEND... ...LIFE-THREATENING AND CATASTROPHIC FLASH FLOODING AND LANDSLIDES EXPECTED IN PORTIONS OF SOUTHERN HISPANIOLA AND JAMAICA THROUGH THE WEEKEND... SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...16.5N 75.1W ABOUT 155 MI...245 KM SE OF KINGSTON JAMAICA ABOUT 235 MI...375 KM SW OF PORT AU PRINCE HAITI MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H PRESENT MOVEMENT...WNW OR 285 DEGREES AT 1 MPH...2 KM/H MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES