GaWx

As of 10AM EST, this was upgraded to TD#18: 1000 AM EST Mon Nov 04 2024 ...SYSTEM BECOMES A TROPICAL DEPRESSION... ...HURRICANE WATCH ISSUED FOR PORTIONS OF CUBA... SUMMARY OF 1000 AM EST...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...15.2N 76.9W ABOUT 195 MI...310 KM S OF KINGSTON JAMAICA ABOUT 400 MI...645 KM SE OF GRAND CAYMAN MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...N OR 10 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Cuba has issued a Hurricane Watch for the provinces of Pinar del Rio, Artemisa, La Habana, Mayabeque, Matanzas, and the Isle of Youth, and a Tropical Storm Watch for Villa Clara, Cienfuegos, Sancti Spiritus, Ciego de Avila, Camaguey, and Las Tunas. Tropical Depression Eighteen Discussion Number 4 NWS National Hurricane Center Miami FL AL182024 1000 AM EST Mon Nov 04 2024 Data from the Air Force Hurricane Hunters, satellite images, and surface observations indicate that the low pressure system over the south-central Caribbean Sea has developed a well-defined center and is producing organized deep convection. Therefore, the system now meets the criteria of a tropical depression. The maximum flight-level winds from the aircraft support holding the initial wind speed steady at 30 kt. Deep convection is gradually organizing near the center and in bands around it, especially on the south and east sides of the circulation. The depression has jogged a bit to the right of the previous track, and the initial motion estimate is now 010/8 kt. A turn to the northwest is expected later today, and that motion is forecast to continue during the next few days as a ridge builds over the southwestern Atlantic and northeastern Caribbean. This motion should take the center of the system near Jamaica tonight, near or over the Cayman Islands by late Tuesday, and across western Cuba on Wednesday. After that time, when the system reaches the Gulf of Mexico, the model solutions diverge, which appears to be due to differences in the steering patterns and vertical depth of the storm. The NHC track forecast is largely an update of the previous one and remains close to the various consensus models. However, it should be noted that the track forecast over the Gulf of Mexico is of low confidence. The environmental factors of low wind shear, high moisture, and warm SSTs support intensification, and since the system now has a well organized circulation, there is increasing confidence of steady strengthening until the system reaches Cuba or the southeastern Gulf of Mexico. In 3 or 4 days, when the system reaches the central Gulf, a sharp increase in southwesterly vertical wind shear, drier air, and slightly cooler waters should end the strengthening trend and induce weakening. The NHC intensity forecast lies near the middle of the guidance envelope, fairly close to the HCCA and IVCN consensus aids.

1. Thus, the difference between ONI and RONI has steadied out in the low to mid 0.50s after having peaked in the 0.60s earlier in the year. This makes me think it might not drop below 0.50 anytime soon. 2. Most SST anomaly measures have risen over the last week or so fwiw. Is it possible the low has already been reached? Opinions?

The following Jan-Mar after the very strong -PDO of 1894 was actually quite cold in most of the US. The PDO rose sharply to the -0.86 to -0.64 range during JFM. This included what is still the coldest Feb on record for the SE US and other locations.

New one on TWO that most models at least hint at: Tropical Weather Outlook NWS National Hurricane Center Miami FL 100 PM EST Sun Nov 3 2024 Southwestern Atlantic: An area of disturbed weather is expected to develop near the northern Leeward Islands around the middle of the week. Some slow development of this system is possible after that time as it moves generally westward over the southwestern Atlantic. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 7 days...low...20 percent.

I really wish a “wow” reaction would be added! This means not only a record -PDO month back 170 years, but also a new record for 2 months of -3.67 breaking old record of July-Aug 1950’s -3.31. Also, there are additional multi-month records like for Jan-Oct of 2024’s -2.59, which beats the -2.55 of Jan-Oct of 1894.

Based on preliminary stats, October of 2024 had the 5th highest ACE on record for any Oct back to 1851: 1. 1878: 87.8 2. 1894: 76.1 3. 2016: 71.3 4. 1893: 67.5 5. 2024: 66.8 (preliminary) 6. 1963: 63.1

Turn back your clocks! Here’s the 1AM EST TWO: Tropical Weather Outlook NWS National Hurricane Center Miami FL 100 AM EST Sun Nov 3 2024 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: Active Systems: The National Hurricane Center is issuing advisories on Subtropical Storm Patty, located over the northeastern Atlantic Ocean near the Azores Islands. 1. Southwestern Caribbean Sea (AL97): Disorganized showers and thunderstorms continue in association with a broad area of low pressure over the southwestern Caribbean Sea. Gradual development of this system is expected, and a tropical depression is likely to form within the next couple of days while moving generally northward to northwestward over the central and western Caribbean Sea. Regardless of development, locally heavy rains are possible over portions of the adjacent land areas of the western Caribbean, including Jamaica, Hispaniola, and Cuba. Interests in the western Caribbean Sea should monitor the progress of this system. An Air Force Hurricane Hunter aircraft is scheduled to investigate this system later today. * Formation chance through 48 hours...high...80 percent. * Formation chance through 7 days...high...90 percent. 2. Near the Greater Antilles: A trough of low pressure just north of Hispaniola and Puerto Rico continues to produce disorganized showers and thunderstorms along with gusty winds over the adjacent waters of the southwestern Atlantic. Slow development of this system is possible during the day or two while it moves westward near the Greater Antilles. By early this week, this system is expected to be absorbed into the low pressure area over the Caribbean Sea (AL97). Regardless of development, locally heavy rains are possible during the next couple of days across the northern Leeward Islands, Puerto Rico, Hispaniola, eastern Cuba, and the southeastern Bahamas. * Formation chance through 48 hours...low...10 percent. * Formation chance through 7 days...low...10 percent.

Based on the WBC daily PDOs for Oct vs Sep being very slightly more negative, I’m guessing Oct NOAA PDO will not quite reach the record low of -3.65 and will be -3.60 (vs Sep’s -3.54). This will be only the 2nd time on record that there were back to back sub -3 months! The other time was way back in 1894, when there actually were three in a row. https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

This became Invest 97L yesterday. Most models have it becoming a TC but interestingly the 0Z UKMET dropped it for TCG. I think it will be wrong. It still has a surface low, regardless.

The storm nearing the Azores is now Invest 96L. This could become Patty soon.

After the 11” I got from Debby along with the very wet summer overall, I’ve been fine with the dry since and loved the lower RH of that cool period in Oct. But I agree that’s it’s now dry enough.

The new TT CANSIPS is the mildest run yet and suggests a mild winter for the E/SE/SC US though Michigan is NN to BN. Regardless, there will very likely be at least a couple of BN periods interspersed as is the case just about every winter due to typical ups and downs but when, how intense, and for how long?

The new TT CANSIPS precip map for DJF is mainly BN for the E seaboard and especially for the SE US (pretty similar to prior runs)(New England is only slightly BN to NN)(Mich/Midwest is NN).

New CANSIPS for DJF is similarly dry to recent runs and is drier in terms of both anomalies and especially absolutes the more SE one is like myself and @pcbjr

NHC is playing catch up with this one approaching the Azores: North Atlantic: A low pressure system located a few hundred miles west of the Azores has been producing increased convection near its center over the past few hours. Earlier satellite derived wind data depicted winds to storm-force mainly to the south of the the center. Environmental conditions appear favorable for some additional development and the system could become a subtropical or tropical storm as it moves generally eastward during the next few days. Interest in the Azores should monitor the progress of this system. Additional information on this system is available in High Seas Forecasts issued by the National Weather Service. * Formation chance through 48 hours...medium...40 percent. * Formation chance through 7 days...medium...40 percent.

La Niña climo once the tropics get quiet is not kind to especially the SE half of the SE US for rainfall with SE ridge typically pretty dominant and the lack of a strong ST jet. A general BN rainfall pattern is forecasted by the model consensus through December.

Yeah it doesn’t develop it much, but the UKMET normally downplays strength significantly before a TC forms.

The population weighted US will continue to cool in the absolute sense as it almost has to, but it is forecasted to continue running about half a month behind climo averages, which is quite an anomaly for the country as a whole during a period of the most rapid fall in climo for dailies.

For W Caribbean cherry, 12Z UKMET is even further N as it doesn’t even cross the Yucatan on NW trek into middle of the Gulf: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 96 HOURS FORECAST POSITION AT T+ 96 : 17.5N 80.9W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 05.11.2024 96 17.5N 80.9W 1004 31 0000UTC 06.11.2024 108 18.5N 82.8W 1004 33 1200UTC 06.11.2024 120 20.8N 84.7W 1004 31 0000UTC 07.11.2024 132 21.9N 87.2W 1003 33 1200UTC 07.11.2024 144 23.8N 88.5W 1002 37 0000UTC 08.11.2024 156 24.7N 89.7W 1002 35 1200UTC 08.11.2024 168 25.4N 91.4W 1004 37

The Oct 31st CANSIPS is the 3rd run in a row with a Modoki El Niño getting established in the summer of 2025. Now if only the W Pac marine heatwave/extreme -PDO would subside.

8PM TWO: Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 PM EDT Thu Oct 31 2024 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Southwestern Caribbean Sea: A broad area of low pressure is likely to develop over the southwestern Caribbean Sea during the next day or so. Gradual development is possible thereafter, and a tropical depression could form over the weekend or early next week while the system drifts generally northward or northwestward over the central or western Caribbean Sea. Regardless of development, locally heavy rains are possible over portions of the adjacent land areas of the western Caribbean. * Formation chance through 48 hours...low...10 percent. * Formation chance through 7 days...medium...60 percent. 2. Northeastern Caribbean Sea and Greater Antilles: A trough of low pressure near Puerto Rico is producing widespread cloudiness and showers over the Dominican Republic, Puerto Rico, the Virgin Islands, the northern Leeward Islands, and the adjacent waters of the Atlantic and the northeastern Caribbean. Slow development of this system is possible during the next 2-3 days as it moves west-northwestward near the Greater Antilles. After that time, this system is expected to be absorbed into the low pressure area over the Caribbean. Regardless of development, locally heavy rains are possible during the next several days from the northern Leeward Islands westward across Puerto Rico and Hispaniola to eastern Cuba and the southeastern Bahamas. * Formation chance through 48 hours...low...10 percent. * Formation chance through 7 days...low...10 percent. 3. North Atlantic: A storm-force non-tropical low pressure area located about 500 miles west of the western Azores is producing limited shower activity. Some subtropical development is possible while the low moves generally eastward during the next few days. Additional information on this system is available in High Seas Forecasts issued by the National Weather Service. * Formation chance through 48 hours...low...20 percent. * Formation chance through 7 days...low...20 percent.

Euro Weeklies through mid Dec no change: very strong SPV, solidly AN temps E 2/3 of US.

Mild has been fully expected by me for Nov and at least Dec. This map is actually not that dry.

1. 12Z Ensembles regarding Conus: active with highest % hitting as a TC on CDN (most members), GEFS at 50%, and lowest on Euro (~30%). These are mainly, though not entirely, coming from the W Caribbean. There are also members with hits on the US from TCs that lose TC status before hitting. 2. 12Z UKMET: TCG at hour 96 in W Car that moves WNW into Yucatan: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 96 HOURS FORECAST POSITION AT T+ 96 : 13.9N 78.4W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 04.11.2024 96 13.9N 78.4W 1004 38 0000UTC 05.11.2024 108 14.5N 79.0W 1002 38 1200UTC 05.11.2024 120 15.3N 79.7W 1001 37 0000UTC 06.11.2024 132 15.9N 81.8W 999 34 1200UTC 06.11.2024 144 17.0N 83.9W 998 40 0000UTC 07.11.2024 156 17.8N 86.7W 996 41 1200UTC 07.11.2024 168 18.3N 89.1W 997 36 ———————— Edit: 0Z UKMET: further N with a WNW crossing of the N Yucatan followed by NW turn into Gulf NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 90 HOURS FORECAST POSITION AT T+ 90 : 14.6N 78.5W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 05.11.2024 96 15.2N 78.7W 1003 31 1200UTC 05.11.2024 108 16.3N 80.3W 1002 30 0000UTC 06.11.2024 120 17.2N 81.8W 1001 31 1200UTC 06.11.2024 132 18.6N 83.9W 1000 34 0000UTC 07.11.2024 144 19.5N 86.3W 999 34 1200UTC 07.11.2024 156 21.4N 88.9W 999 34 0000UTC 08.11.2024 168 22.4N 90.9W 997 36

0Z Euro ensemble mean next 2 wks: still well below normal US pop weighted HDDs (~2/3 of the normal) and well above normal CDDs (~4 times the norm): normally US HDDs are ~23 times CDDs during this period but this fcast has HDDs only ~3.5 times CDDs. HDDs are rising and are forecasted to get to almost normal on 11/2 and 11/9, but then they fall back and still are not averaging anywhere near normal overall. Instead, the fcast has HDDs averaging a whopping nearly ~3.5 BN/day. In other words, the pop weighted US is forecasted to average a whopping ~3.5F/day AN for the period 10/31 through 11/13! The fcast averages 7.4 HDD/day, which is the normal US pop wted HDDs for Oct 24th. That means that this period overall is forecasted to be at US HDD levels from ~2 weeks earlier.