GaWx

This is for Nolo, which is a threat to the Big Island of Hawaii: 000 WTPA42 PHFO 241450 TCDCP2 Tropical Storm Nolo Discussion Number 16 NWS Central Pacific Hurricane Center Honolulu HI EP152026 Issued by NWS National Hurricane Center Miami FL 500 AM HST Thu Sep 24 2026 Satellite images indicate that Nolo is gradually becoming better organized, with very deep convection in a curved band on the southern and western side of the circulation. Additionally, a GPM pass from overnight indicated that an inner core is forming, although the eastern side is fragmented. Intensity estimates are rising, and the current wind speed is set to 50 kt as a blend of the lower subjective and higher objective values. Nolo has not moved much during the last several hours but should begin to move northward and north-northeastward later today due to a mid-latitude trough dropping over the northwestern Hawaiian Islands. The trough is forecast to move westward by Saturday with a building ridge north of the main Hawaiian Islands, causing a sharp westward turn this weekend. The big question is how close does Nolo get before making that turn, with notable run-to-run inconsistencies in much of the guidance. Similar to the last cycle, the bulk of the models have shifted slightly northward, and the new NHC forecast is moved in that direction. This remains a more uncertain forecast than normal given the large unresolved north-south spread, with other possible complicating terrain influences of the Big Island (like we saw with Hurricane Lala last month). Therefore, the long-range portion of the forecast is essentially unchanged. With the formation of an inner core, conditions appear to be coming together for rapid intensification given the other conducive environmental factors of warm SSTs, low shear and high mid-level moisture. Nolo is likely to become a hurricane by tonight and reach major hurricane strength as it nears the Big Island on Saturday. The new forecast is raised from the previous one, just below the HCCA aid, which has done well this year in these strengthening episodes. Note that a track closer to the Big Island could substantially increase the threat of damaging winds, particularly over higher terrain, along exposed ridges, and in areas downwind of the ridges. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 14.9N 156.2W 50 KT 60 MPH 12H 25/0000Z 15.2N 156.2W 65 KT 75 MPH 24H 25/1200Z 16.1N 155.8W 80 KT 90 MPH 36H 26/0000Z 17.1N 155.4W 95 KT 110 MPH 48H 26/1200Z 17.8N 155.4W 100 KT 115 MPH 60H 27/0000Z 18.0N 156.4W 105 KT 120 MPH 72H 27/1200Z 18.1N 158.2W 105 KT 120 MPH 96H 28/1200Z 19.0N 162.0W 105 KT 120 MPH 120H 29/1200Z 21.6N 164.4W 90 KT 105 MPH $$ Forecaster Blake

From NHC: Resilient Fay has strengthened this morning. Deep convective curved bands have developed both on the west and east sides of the cyclone, and a small cold cloud top deep burst of convection is persisting over the surface center. Based on the improved cloud pattern and an increase in the Dvorak satellite intensity estimated from TAFB, the initial intensity is raised to 45 kt. Fay remains over warm ocean waters and a favorable upper-level wind environment. Only a relatively stable, dry surrounding atmosphere is preventing Fay from strengthening significantly. By the weekend, deep-layer shear is expected to increase, which should induce a weakening trend. Subsequently, Fay is forecast to degenerate into a remnant low. Fay's initial motion is estimated to be due west, or 270/5 kt. This general motion should continue with a slight reduction in forward speed through dissipation on Sunday. The NHC track forecast is similar to the previous advisory and lies close to the skilled HFIP HCCA and GDMI TC ensemble mean. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 29.8N 41.2W 45 KT 50 MPH 12H 25/0000Z 29.8N 42.0W 50 KT 60 MPH 24H 25/1200Z 29.7N 42.9W 45 KT 50 MPH 36H 26/0000Z 29.6N 43.9W 40 KT 45 MPH 48H 26/1200Z 29.5N 45.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 27/0000Z 29.5N 46.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 27/1200Z...DISSIPATED $$ Forecaster Roberts

When was the comparable last nasty cold core nor’easter that occurred in your area as early as late Sept? The ones I recall off the top of my head for your area waited at least til Oct and were mainly in the latter half of Oct to boot.

*Fwiw* recent 3 day (12 run) CFSv2 runs for Feb have been cooling back down again. The coldest I’ve seen was the very cold Aug 7-9th mean. The warmest was the recently posted Sep 16-18th mean. The newest (Sep 21-23st) is right in between those:

Thanks. Do you see it having a chance to transition from cold core, which we all agree it will start as, to ST status?

Then the NHC should be adding it to its TWOs since those address the chance for both T and ST development. Adding it to its TWOs has been suggested by both JB and @vortex95

This from the 0Z Euro suite per pro met@vortex95shows a 70-80% chance for tropical development! How do you explain this?

0Z UKMET goes NNE to eastern end of LI and then into SE New England while weakening substantially Mon-Tue

Thanks. But how do you explain a 1000/500 mb thickness max of >576 dm and 700 mb height max both at the center if it is cold core? That almost has to be warm core.

Joe Bastardi, who I often don’t agree with, continues to insist this will transition from baroclinic/cold core to warm core Fri night/early Sat leading to an “eye-like feature” and says it thus should be named. He says the NHC is wrong in not even putting it in its TWOs. He shows the Euro ensemble giving it a 70% chance for tropical development. He said there will be rapid feedback over SSTs that are abnormally warm (well above 79F) due largely to GW. Per JB, evidence of it being warm-core is that it starts to weaken as it moves NW into cooler SSTs followed by it dissipating as it makes landfall. Also, he posted the Euro having a warm center offshore on Sun AM at 700 mb! He shows 1000/500 mb thicknesses peaking at the center at >576 dm! He compares this projected weakening over cooler SSTs to Henri of ‘21 as it approached the NE. He said tides may go as high as 3-6 feet AN at NYC! Does anyone here recall a purely cold-core nor’easter in this region this early in the fall? Aren’t those usually not til Oct, when SSTs aren’t as warm?

As I posted above, JB is insisting this will transition from baroclinic/cold core to warm core Fri night/early Sat leading to an “eye-like feature” and says it should be named. He agrees with you that the NHC is wrong in not even putting it in its TWOs. He shows the Euro ensemble giving a 70% chance for tropical development. He said there will be rapid feedback over SSTs that are abnormally warm due largely to GW. More evidence of it being warm-core is that it starts to weaken as it moves NW into cooler SSTs followed by it dissipating as it makes landfall. Also, the Euro has a warm center offshore on Sun AM at 700 mb! He shows 1000/500 mb thicknesses peaking at the center at >576 dm! He compares this weakening over cooler SSTs to Henri of ‘21 as it approached the NE. You mentioned that you don’t recall a nor’easter like this in Sept. I don’t either. They’re usually not til Oct, when SSTs aren’t as warm. He said tides may go to 3-6 feet AN!

“Lame” is good for us SE folks, especially those of us with elderly loved ones. Many in the SE US, even well inland, have had a very rough 2016-24. I was heavily affected by 5 storms. I’ll always take the very rare quiet season over that, especially because it will likely not be quiet next year.

Walt, My nephew has a trip planned to NYC for Thu-Sun. I don’t know where he’ll be staying, where he’ll be going, and whether or not he’ll be that close to water (probably not). I’d like your opinion. Is the risk for major disruptions in NYC high enough to make you feel he should consider postponing this trip? Or should he still go there? Thanks.

Brian, how bad would the coastal flooding be in NYC if this track were to verify closely? Would it be very high impact for the city?

There are two AOI in the Atlantic being monitored by the NHC, Invest 90L just off Africa and a possible regenerating Fay: Tropical Weather Outlook NWS National Hurricane Center Miami FL 200 PM EDT Wed Sep 23 2026 For the North Atlantic...Caribbean Sea and the Gulf of America: 1. Far Eastern Tropical Atlantic (AL90): An area of low pressure located a couple of hundred miles southwest off the coast of western Africa is gradually becoming better defined, and the associated shower and thunderstorm activity has increased since yesterday. This system could become a short-lived tropical depression on Thursday or Friday while it moves northwestward to northward. However, strong upper-level winds should end the opportunity for development by the weekend. Interests in the Cabo Verde Islands should monitor the progress of this system as gusty winds, areas of heavy rain and flash flooding is possible there by Friday. * Formation chance through 48 hours...medium...50 percent. * Formation chance through 7 days...medium...50 percent. 2. Central Subtropical Atlantic (Former Tropical Storm Fay): Showers and thunderstorms have increased with the remnants of Fay located several hundred miles southwest of the Azores. While environmental conditions are only marginally conducive for development, this system could become a tropical depression again today or tonight if the current thunderstorm activity persists. The system is forecast to move westward during the next couple of days, and by the weekend upper-level winds should inhibit formation chances. * Formation chance through 48 hours...high...70 percent. * Formation chance through 7 days...high...70 percent. Forecaster Blake ——————— Edit: 12Z UKMET has Fay not only hanging around for at least 168 hrs but being its strongest at hour 168 as it slowly moves WSW! TROPICAL CYCLONE DEVELOPED IN THE MODEL ANALYSIS AT POSITION : 30.2N 37.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 23.09.2026 0 30.2N 37.7W 1015 27 0000UTC 24.09.2026 12 29.8N 39.3W 1014 27 1200UTC 24.09.2026 24 30.1N 41.0W 1015 29 0000UTC 25.09.2026 36 30.5N 41.9W 1015 26 1200UTC 25.09.2026 48 30.7N 42.7W 1014 28 0000UTC 26.09.2026 60 30.6N 43.3W 1014 28 1200UTC 26.09.2026 72 30.6N 43.9W 1013 29 0000UTC 27.09.2026 84 30.5N 44.0W 1014 25 1200UTC 27.09.2026 96 30.3N 43.7W 1013 28 0000UTC 28.09.2026 108 29.5N 43.5W 1013 27 1200UTC 28.09.2026 120 28.4N 43.7W 1012 28 0000UTC 29.09.2026 132 27.4N 44.8W 1011 29 1200UTC 29.09.2026 144 26.5N 46.4W 1009 31 0000UTC 30.09.2026 156 25.7N 48.0W 1008 34 1200UTC 30.09.2026 168 25.0N 49.2W 1004 39

I have a family member planning to visit NYC Thu-Sun. Is it going to be bad enough for him to consider canceling? What are the chances of major coastal flooding causing a big mess through much of NYC? TIA

From the 11AM EDT advisory for TD 15E: ...INTERESTS IN THE HAWAIIAN ISLANDS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM... SUMMARY OF 500 AM HST...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...14.5N 154.4W ABOUT 320 MI...520 KM SSE OF SOUTH POINT HAWAII ABOUT 525 MI...840 KM SSE OF HONOLULU HAWAII MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...WNW OR 290 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES WATCHES AND WARNINGS -------------------- Interests in the Hawaiian Islands should closely monitor the progress of this system. A Hurricane or Tropical Storm Watch will likely be required for a portion of the state later today. —————————— The depression has slowed since the last advisory and seems to be moving west-northwestward at about 5 kt. A ridge to the northeast of Hawaii is forecast to weaken and slide eastward as a mid- latitude trough drops over the northwestern Hawaiian islands. This evolution is likely to the cause the cyclone to slow down later today or tonight and then turn northward or north- northeastward by tomorrow with some increase in forward speed. The trough is forecast to move westward this weekend as the ridge rebuilds north of Hawaii, which should force a sharp westward turn while the cyclone is close to the Big Island. At this time frame, it is impossible to know exactly when that turn will happen and, unsurprisingly, there is a large north-south spread in the guidance. Our best guidance is on the northern side of the track envelope, and new NHC forecast remains essentially the same as the last advisory. Interests in the Hawaiian Islands, especially on the Big Island, should closely monitor the system, with life-threatening catastrophic flooding possible over the steep terrain on this track. The depression should intensify slowly at first, given the current structure of the low-level center not co-located with the mid-level circulation as seen on satellite. However, after the system develops an inner core, the environment seems conducive for significant strengthening, with low shear, high mid-level moisture and SSTs from 28-29C. The rapid intensification probabilities are increasing, and the best model guidance is showing this as a major hurricane in a few days. Given the environment and the best-performing aids (Google DeepMind and HCCA) again showing major-hurricane strength, the NHC forecast is raised from the previous one and shows the cyclone as a major hurricane when it approaches the Big Island of Hawaii by the weekend. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 14.5N 154.4W 30 KT 35 MPH 12H 24/0000Z 14.7N 155.2W 40 KT 45 MPH 24H 24/1200Z 15.0N 155.5W 50 KT 60 MPH 36H 25/0000Z 15.7N 155.2W 65 KT 75 MPH 48H 25/1200Z 16.7N 154.8W 80 KT 90 MPH 60H 26/0000Z 17.6N 154.5W 90 KT 105 MPH 72H 26/1200Z 18.2N 154.7W 100 KT 115 MPH 96H 27/1200Z 18.1N 157.0W 100 KT 115 MPH 120H 28/1200Z 18.7N 160.2W 95 KT 110 MPH $$ Forecaster Blake

The very rough 2026 for Hawaii looks to get even rougher later this week! TD 15E had formed in the E PAC back on Sep 13th from an AEW that had moved off of Africa way back on Aug 27th. This was actually the very next wave after the one that produced Dolly in the Atlantic! This then degenerated in the E PAC into an open wave late on Sep 15th. But one week later (late last night), this reorganized back to TD 15E 405 miles SSE of Hilo, Hawaii, moving WNW. It’s forecasted to become a TS later today and then turn sharply N tonight. It is then forecasted to become a H tomorrow night and reach high end cat 2 H status Fri night while not too far S of the big island of Hawaii meaning a potential serious threat there then: From the NHC discussion: The depression is moving west-northwestward at about 10 kt on the southwest side of a low- to mid-level ridge. This ridge is expected to shift eastward and weaken while a mid- to upper-level low dives southwestward near the northwestern Hawaiian Islands. This pattern change should cause the cyclone to slow down and then turn northward or north-northeastward later this week. That motion should take the cyclone near the Big Island of Hawaii late Friday or on Saturday. Around that time, the upper low is expected to weaken and move westward, allowing mid-level ridging to become re-established to the north of the system. In response, the cyclone should turn and then accelerate westward. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 14.0N 153.7W 30 KT 35 MPH 12H 23/1800Z 14.4N 154.7W 35 KT 40 MPH 24H 24/0600Z 14.6N 155.5W 45 KT 50 MPH 36H 24/1800Z 15.0N 155.6W 55 KT 65 MPH 48H 25/0600Z 15.9N 155.2W 70 KT 80 MPH 60H 25/1800Z 17.0N 154.9W 85 KT 100 MPH 72H 26/0600Z 17.9N 154.7W 95 KT 110 MPH 96H 27/0600Z 18.3N 156.0W 95 KT 110 MPH 120H 28/0600Z 18.2N 159.0W 95 KT 110 MPH

I just noticed that CHS this afternoon lowered my temps for late week into the weekend to the solidly BN range, thanks at least in part to the big nor’easter off the NE US: FRIDAY SUNNY. HIGHS IN THE UPPER 70S. FRIDAY NIGHT MOSTLY CLEAR. LOWS IN THE UPPER 50S. SATURDAY SUNNY. HIGHS AROUND 80. SATURDAY NIGHT MOSTLY CLEAR. LOWS IN THE UPPER 50S. SUNDAY MOSTLY SUNNY. HIGHS IN THE MID 80S. The treadmill may get a break during this period! Hello park! It’s a wonderful time of the year!

Joe Bastardi makes a good point about this likely being warm core at least in the early stages since it would be forming over 82-83F water. He said it weakens as it moves toward the coast because that’s what a warm core storm would do as it gets into cooler SSTs.

Also, regardless of upwelling, this like all TCs of course removes heat from the upper layers of the ocean (potential energy) since that heat is converted to kinetic energy (conservation of energy). So that, alone, should always induce its own cooling even without upwelling per se. And a very strong one like Polo should be taking heat from the ocean at a more rapid rate than a weaker one. That, alone, often brings the SSTs in and near the center down 1-2C based on my following SSTs in the past with deep warmth.

A batch of heavy showers has popped up, which lead to mainly heavy rain starting at 12:50PM. It is continuing to rain at a moderate rate and this is adding up nicely. 1/2”++ has already fallen. The showers are moving SSW. Before today, I had received 2” MTD. So, these are beneficial rains. Edit: I estimate a total of 0.55” on Sep 22nd, which brings me to ~2.55” MTD.

This is tricky. Whereas cyclonicwx’s OISST graph has indeed had it at +2.5 for the past 10 days including last week, keep in mind that NOAA had it at only +2.1 for last week. Thus, NOAA had it 0.4 cooler than cyclonicwx’s OISST graph. Actually, NOAA has been cooler than cyclonicwx by 0.4 for 9 straight weeks! NOAA labels their weeklies as OISSTv2.1. Thus, I wonder if cyclonicwx uses an older version of OISST. If so, that could possibly explain the 0.4 difference for the last 9 weeks. Note that cyclonicwx in late June/early July was warmer by only 0.1. I wonder if the latest version of OISST started being used just after that. So, per NOAA, last week’s equivalent RONI (based on OISSTv2.1) was still only +2.1. So, with that being the case, there’s quite a ways to go to see if it actually does reach a +3.0 trimonthly peak per NOAA. NOAA Weeklies: https://www.cpc.ncep.noaa.gov/data/indices/rel_wksst9120.txt *Edit: I just found out that OISSTv2.1 was first implemented way back on 4/26/2020: https://www.ncei.noaa.gov/products/optimum-interpolation-sst So, it remains a mystery why cyclonicwx’s OISST graph has been 0.4 warmer than NOAA’s OISSTv2.1 based weeklies for 9 weeks! So, until NOAA’s weeklies get close to cyclonicwx (if they do), I’ll continue to treat cyclonicwx’s OISST graphs as too warm vs NOAA. The NOAA August’s +1.67, which is ERSSTv6 based, was even a little cooler than NOAA’s OISSTv2.1 based weeklies would have suggested! So, NOAA and cyclonicwx are world’s apart.

The latest CFSv2 RONI peak prog unlike for recent days doesn’t have most of the blue lines underneath most of the red lines. When it did, that predicted well the subsequent reductions in the progged peak, which came all the way down to +2.8 from +3.5 in late July. The current configuration is much more balanced and even has the average blue a little warmer than the avg. red. Thus, I don’t expect more drops in the progged peak over the next few days and there’s even a small chance for a slight bounce upward:

Whereas historical stats certainly agree that La Niña is quite possible in ‘27-‘28, that same history says that there’s actually a decent chance for either neutral or, believe it or not, even El Niño in ‘27-‘28. Here’s why: El Niños peaking at +1.4+ occurred in the following 19 fall/winters and were followed by these: +1.4+ Nino: subsequent fall/winter ENSO 1877-8: cold neutral 1888-9: strong Nina 1896-7: cold neutral 1899-1900: warm neutral 1902-3: moderate Nina 1905-6: weak Nina 1918-9: weak Nino 1930-1: cold neutral 1940-1: moderate Nino 1957-8: weak Nino 1965-6: cold neutral 1972-3: strong Nina 1982-3: moderate Nina 1986-7: moderate Nino 1991-2: weak Nino 1997-8: strong Nina 2009-10: strong Nina 2015-6: moderate Nina 2023-4: moderate Nina ————————— So, these 19 +1.4+ El Niños were followed by these: Strong Niña: 4 (21%) Moderate Nina: 4 (21%) Weak Nina: 1 (5%) Cold neutral: 4 (21%) Warm neutral: 1 (5%) Weak Nino: 3 (16%) Moderate Nino: 2 (11%) ————————— Tally: 47% Nina 26% neutral 26% El Nino ——————— Conclusion: La Nina is the best single possibility for ‘27-‘28 due to its large plurality (being at 47%), but neutral or even El Niño are obviously each quite possible as the two of them, combined, actually occurred about as often as La Nina after these strongest 19 El Niños on record. https://www.webberweather.com/ensemble-oceanic-nino-index.html https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/