GaWx

With the globe ~2 F warmer than 77-78, do you think there can still be a winter as cold as just 2F warmer than 77-78? For example: Ten coldest Savannah winters since 1875-6: 1977-8: 45.8 (~6BN) 1976-7: 46.0 1957-8: 46.2 1969-70: 46.4 1963-4: 46.6 1962-3: 47.0 1968-9: 47.3 2009-10: 47.8 1980-1: 48.0 2010-1: 48.1 So, if an upcoming Savannah winter were to be 2F warmer than 1977-8, it would be 47.8. That would still be tied for 8th coldest, a top 10 winter. Aside: Note that 7 of the 8 coldest were during El Niño.

Well, the good news for him is that they’re not explicitly predicting a warm winter in his area. They’re literally just saying ~55% chance of AN winter (not far from a coin flip). Furthermore, AN includes just a few degrees AN, which could accommodate a cold Feb. Also, in just over half the lower 48, they’re saying equal chances or only 1/3 chance for AN. For NOAA, the map as a whole doesn’t seem torchy to me. With the way NOAA does these maps, this winter could end up cold in most of the lower 48 and they could correctly claim they weren’t explicitly wrong.

More from the 11AM NHC PTC #16 advisory: WIND: Tropical storm conditions are expected to first reach the coast within the warning area in North Carolina on Friday, and spread northward Friday night and Saturday. RAINFALL: The system is forecast to produce 2 to 4 inches of rainfall, with localized amounts of 6 inches, across the eastern Mid-Atlantic states from North Carolina to New Jersey, Friday through Sunday. This rainfall may produce localized urban and small stream flooding impacts. SURF: Swells generated by this system will be affecting much of the east coast of the United States through this weekend. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

BULLETIN Potential Tropical Cyclone Sixteen Advisory Number 1 NWS National Hurricane Center Miami FL AL162023 1100 AM EDT Thu Sep 21 2023 ...LOW PRESSURE AREA EXPECTED TO BRING TROPICAL STORM CONDITIONS AND THE POTENTIAL FOR LIFE-THREATENING STORM SURGE TO PORTIONS OF THE SOUTHEAST AND MID-ATLANTIC COASTS... SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...28.7N 75.9W ABOUT 370 MI...595 KM SE OF CHARLESTON SOUTH CAROLINA ABOUT 450 MI...725 KM S OF CAPE HATTERAS NORTH CAROLINA MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...N OR 10 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...1012 MB...29.89 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Warning has been issued from Cape Fear, North Carolina, northward to Fenwick Island, Delaware, including Albemarle and Pamlico Sounds, and the Chesapeake Bay south of Smith Point. A Storm Surge Watch has been issued from Surf City, North Carolina to Chincoteague, Virginia, and the for the Chesapeake Bay south of Smith Point, including Albemarle and Pamlico Sounds. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Cape Fear NC to Fenwick Island DE * Chesapeake Bay south of Smith Point * Albemarle and Pamlico Sounds A Storm Surge Watch is in effect for... * Surf City NC to Chincoteague VA * Chesapeake Bay south of Smith Point * Albemarle and Pamlico Sounds DISCUSSION AND OUTLOOK ---------------------- At 1100 AM EDT (1500 UTC), the disturbance was centered near latitude 28.7 North, longitude 75.9 West. The system is moving toward the north near 9 mph (15 km/h), and this general motion is expected to continue through early Friday. A north-northwestward to northward motion is forecast by late Friday and continue into the weekend. On the forecast track, the center of the cyclone is expected to approach the coast of North Carolina within the warning area Friday night and early Saturday. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Strengthening is expected during the next day or two, and the system is forecast to become a tropical storm as it approaches the coast of North Carolina. Regardless of whether the system become a tropical storm, the system is expected to bring tropical-storm conditions to portions of the southeast and mid-Atlantic coast. * Formation chance through 48 hours...medium...60 percent. * Formation chance through 7 days...medium...60 percent. The estimated minimum central pressure is 1012 mb (29.89 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for this system can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT1 and WMO header WTNT41 KNHC and on the web at hurricanes.gov/text/MIATCDAT!.shtml STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Surf City NC to Chincoteague VA...2-4 ft Chesapeake Bay south of Smith Point...2-4 ft Albemarle and Pamlico Sounds...2-4 ft South Santee River SC to Surf City NC 1-3 ft Chincoteague VA to Fenwick Island DE...1-3 ft

This is now PTC 16: Potential Tropical Cyclone Sixteen Discussion Number 1 NWS National Hurricane Center Miami FL AL162023 1100 AM EDT Thu Sep 21 2023 A broad non-tropical area of low pressure has formed well east of the east coast of Florida this morning. Although this system is forecast to remain non-tropical during the next 12-24 hours, the dynamical model guidance indicates that it will likely acquire tropical characteristics late Friday and early Saturday as it approaches the coast of North Carolina. Although it is unclear as to whether the cyclone detaches from a front that is forecast to extend northeastward from the center, the guidance suggests a tropical-cyclone like core and structure when it nears the coast. As a result, advisories are being initiated on Potential Tropical Cyclone Sixteen to issue Tropical Storm Warnings and Storm Surge Watches for portions of the coasts of North Carolina, Virginia and Maryland. Winds associated with the front farther north are being covered by non-tropical products issued by local National Weather Service offices and the Ocean Prediction Center. Additional tropical watches and warnings could be issued for other portions of the Chesapeake Bay later today. Since the low is still in its formative stage, the initial motion estimate is a highly uncertain 360/8 kt. The model guidance suggests that center reformations are likely to occur during the next day or so, but the overall motion of the system is expected to be a little east of due north. As the system interacts with a mid-latitude trough that it becomes embedded within, a bend toward the north-northwest is forecast. That motion should bring the center over eastern North Carolina within the warning area Saturday morning. The NHC track forecast follows a blend of the various global models that are in good agreement. The system is forecast to gradually strengthen during the next 24 hours. After that time, the guidance suggests it is likely to form a smaller inner core with additional strengthening expected until the center reaches the coast. The NHC intensity forecast follows the ECMWF and GFS models trends. Key Messages: 1. An area of low pressure is forecast to develop off the southeastern U.S. coast later today and will bring tropical-storm-force winds, storm surge, heavy rain, and high surf to large portions of the southeast and mid-Atlantic United States coast beginning Friday and continuing into the weekend. 2. There is the potential for life-threatening storm surge inundation from Surf City, North Carolina to Chincoteague, Virginia, the Pamlico and Albemarle Sounds, and the lower Chesapeake Bay. Residents in these areas should follow advice given by local officials. 3. Tropical storm conditions are expected within portions of the southeast and mid-Atlantic coasts within the Tropical Storm Warning area beginning on Friday and continuing into Saturday. 4. Heavy rainfall from this system could produce localized urban and small stream flooding impacts across the eastern mid-Atlantic states from North Carolina to New Jersey Friday through Sunday. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 28.7N 75.9W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 12H 22/0000Z 30.0N 75.5W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 24H 22/1200Z 31.7N 75.4W 45 KT 50 MPH...POTENTIAL TROP CYCLONE 36H 23/0000Z 33.2N 75.6W 50 KT 60 MPH...TROPICAL CYCLONE 48H 23/1200Z 35.1N 76.4W 50 KT 60 MPH...TROPICAL CYCLONE 60H 24/0000Z 37.3N 76.4W 40 KT 45 MPH...TROPICAL CYCLONE 72H 24/1200Z 38.8N 76.1W 30 KT 35 MPH...POST-TROPICAL 96H 25/1200Z 40.4N 71.8W 25 KT 30 MPH...POST-TROPICAL 120H 26/1200Z...DISSIPATED $$ Forecaster Brown

Whereas 0Z UKMET was 994 mb near Ocracoke, the 6Z UKMET is 992 mb (strongest run yet) ~50 miles further W near Cape Lookout at 5AM EDT Saturday 9/23 and then moves N to 50 miles W of VA Beach at 2PM EDT:

I’m going with a super ONI peak of +2.10 for this contest. This will be fun to follow. The winner(s) should get a free cruise to Nino 3.4 to see those hallowed waters up close and personal!

I was last ~+2.20 for the ONI peak, which was a good bit warmer than my prior strong ONI peak prediction. Based on the slight cooling of the model consensus since last month, I’m lowering my prediction to +2.10 (lower end super Nino). I feel being very slightly warmer than the JMA and a little cooler than the Euro is the best place to be right now.

0Z Euro at 48: strongest run yet at 997 mb 150 mi SE of Wilmington, NC

Now that Sep exact model numbers are out, I can derive the exact model changes from the prior month’s runs: Model: new peak/months (change in peak) BoM: +2.87/DJF (0.00) Met-France: +2.69/NDJ (+0.03) Euro: +2.24/NDJ (-0.16) JMA: +2.06/NDJ (-0.16) UKMET: +1.96/DJF (-0.04) CFSv2: +1.83/NDJ (-0.28) AVG: +2.28/between NDJ and DJF (-0.12)

For the 2nd run in a row, the UKMET (0Z) is too weak for this late in the season MDR storm to be classified a TC.

0Z UKMET: becomes a TC 36 hours earlier vs 12Z run; back on the coast NC to NJ NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 24 HOURS FORECAST POSITION AT T+ 24 : 30.4N 74.8W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 22.09.2023 24 30.4N 74.8W 1007 38 1200UTC 22.09.2023 36 32.4N 75.0W 1004 44 0000UTC 23.09.2023 48 33.4N 75.9W 997 45 1200UTC 23.09.2023 60 35.4N 76.0W 995 43 0000UTC 24.09.2023 72 37.8N 75.7W 994 40 1200UTC 24.09.2023 84 39.1N 74.6W 1001 32 0000UTC 25.09.2023 96 39.9N 73.5W 1007 33 1200UTC 25.09.2023 108 40.0N 72.2W 1009 34 0000UTC 26.09.2023 120 39.5N 69.6W 1011 34 1200UTC 26.09.2023 132 CEASED TRACKING

Is JB copying my posts? I beat him to the punch by 4 hours : I think that another home brew under the next big NE high late next week is much more likely than the 18Z GFS idea of that storm coming all the way to the CONUS. There’s no room for both and the 18Z GFS is an extreme outlier considering its own ensemble, other models, and climo (lateness for that kind of track). A home brew under a big and strong high OTOH wouldn’t be. Of course neither may happen.

Fwiw, 12Z Euro says “Ridge Over Troubled Water” part two late next week with a second big (actually stronger) NE US surface high: https://www.tropicaltidbits.com/analysis/models/?model=ec-fast&region=us&pkg=z500_mslp&runtime=2023092012&fh=216

Thanks. Why wouldn’t Pinatubo add to instead of subtract from the value of 1994-5 as an analog?

Thanks. 1. Why don’t you think Pinatubo adds to the strength of 1994-5 as an analog? 2. Since you and I agree on the idea of attempts to overly attribute wx to AGW even though we both fully accept AGW as real, I thought you might find this reply that I just made interesting regarding an article citing an attempt to partially attribute increased Midwest rainfall in recent decades to AGW:

From this article: But that doesn’t mean global warming has somehow skipped the central US: In a weird twist, climate change may be partly responsible for this gap. Interestingly enough, the conditions that contribute to the hole actually begin thousands of miles to the west, in the tropical Pacific. “Changing ocean surface temperatures, partly caused by global warming and partly caused by naturally occurring variability, are producing the downstream changes in atmospheric circulation over the US,” says Gerald Meehl, a senior scientist at the National Center for Atmospheric Research, who wasn’t involved in the new research. “This paper confirms earlier work that these changes in circulation are bringing this cooler and wetter weather into parts of the eastern US.” This seems like a reach to try to attribute the wetter wx in the Midwest to AGW. This is a very weak argument at best imo. I favor calling it a combo of mainly much higher crop production (which has likely been helped by increased CO2) along with natural variability. Besides, an increase in droughts is supposed to occur due to AGW. I’m not doubting AGW at all (very much unlike Joe Bastardi for example, who’s ignoring scientifically supported facts/evidence). But I do question some of the attempts to attribute too many things to AGW without solid evidence. Overdoing attribution only serves imo to make it more difficult to educate folks about the reality of AGW because I feel it creates straw-men.

What about 1994-5 as a potentially good RONI/PDO/PNA analog? RONI peak (NDJ) was +1.42 while DJF PDO was -1.02. DJF PNA was solidly positive. DJF was central to west based (definitely not east based).

The 12Z UKMET dropped this from becoming a TC. UK goes through 168.

Here was the 0Z UKMET (12Z is further down in this post): NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 66 HOURS FORECAST POSITION AT T+ 66 : 32.2N 76.5W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 23.09.2023 72 34.2N 75.6W 1004 43 1200UTC 23.09.2023 84 36.3N 75.0W 1001 48 0000UTC 24.09.2023 96 39.1N 73.1W 998 42 1200UTC 24.09.2023 108 42.1N 69.4W 998 39 0000UTC 25.09.2023 120 45.5N 64.0W 995 41 1200UTC 25.09.2023 132 46.8N 63.5W 993 45 0000UTC 26.09.2023 144 46.3N 60.6W 999 41 1200UTC 26.09.2023 156 45.9N 55.9W 1005 29 0000UTC 27.09.2023 168 CEASED TRACKING 12Z UKMET is back to being more offshore with a TC: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 72 HOURS FORECAST POSITION AT T+ 72 : 35.5N 74.1W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 23.09.2023 72 35.5N 74.1W 1006 42 0000UTC 24.09.2023 84 37.7N 72.3W 1003 38 1200UTC 24.09.2023 96 40.9N 67.9W 1004 34 0000UTC 25.09.2023 108 43.6N 62.1W 1004 36 1200UTC 25.09.2023 120 43.9N 58.3W 1004 39 0000UTC 26.09.2023 132 CEASED TRACKING

When considering the progged RONI along with assuming a solid -PDO this winter, 1994-5 could easily be the closest analog. The RONI peak was +1.42 (NDJ), which we could end up close to. The DJF PDO was down at -1.02, a strong -PDO. RONI: https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt PDO: https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat But how likely is it that the DJF PDO will be strongly negative though? Does anyone have a good feel for the upcoming DJF PDO? The 30+ moderate+ El Niño events outside of 1994-5 going all of the way back to the 1850s says to look to not have a strongly -PDO.

I’ve found only three storms on record since the late 1800s that have formed in the MDR E of 50W Sep 20+ and hit the CONUS: 1) 2002’s Lili: TD formed 9/21 near 45W and hit LA 10/3 as a H; El Nino 2) 1966’s Inez: TD formed 9/21 near 35W and hit FL Keys 10/4 as a H; not El Niño 3) 1893’s storm #9 formed 9/25 near 25W and hit Carolinas 10/13 as a MH; not El Nino

12Z UKMET had this (0Z is further down in this post): NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 54 HOURS FORECAST POSITION AT T+ 54 : 14.5N 27.2W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 22.09.2023 60 14.5N 29.0W 1008 31 1200UTC 22.09.2023 72 15.0N 32.2W 1007 32 0000UTC 23.09.2023 84 15.3N 34.9W 1006 36 1200UTC 23.09.2023 96 15.8N 37.9W 1005 38 0000UTC 24.09.2023 108 16.3N 39.9W 1005 37 1200UTC 24.09.2023 120 16.7N 42.4W 1004 44 0000UTC 25.09.2023 132 17.4N 44.3W 1003 47 1200UTC 25.09.2023 144 17.3N 46.7W 1003 48 0000UTC 26.09.2023 156 17.2N 48.9W 1003 47 1200UTC 26.09.2023 168 17.1N 49.9W 1001 60 ——————— 0Z UKMET: At 168 hours TS moving W at 15 mph 300 mi NE of Leewards NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 60 HOURS FORECAST POSITION AT T+ 60 : 15.0N 33.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 22.09.2023 60 15.0N 33.7W 1009 30 0000UTC 23.09.2023 72 15.6N 36.3W 1008 30 1200UTC 23.09.2023 84 16.0N 39.3W 1008 31 0000UTC 24.09.2023 96 16.3N 41.7W 1008 30 1200UTC 24.09.2023 108 16.4N 43.6W 1007 37 0000UTC 25.09.2023 120 17.2N 46.4W 1007 36 1200UTC 25.09.2023 132 17.8N 49.2W 1008 37 0000UTC 26.09.2023 144 18.3N 52.1W 1008 42 1200UTC 26.09.2023 156 18.6N 55.5W 1007 42 0000UTC 27.09.2023 168 18.4N 58.2W 1005 37

More on these amateur forecasts with most warm, dry in the NW and cold, snowy E coast: Weather Watcher: what a winter along E coast! Weather William: winter will be rockin’ in the east! Direct Wx: get your shovels ready in the east! America Climate Channel: amazing winter for the east! NWW116 goes big in the east! AWF: Lives in GA and has their coldest and one of snowiest winters of last 45 yrs 2009-10 as top analog! Weather At A (15 minute long) Glance: David S for NE: probably one of worst winters; “big, deep trouble, almost historic, winter-mageddon”! MBGC says wild winter coming, especially NE; 2009-10 favorite analog! Direct Wx’s favorite video of year: official snowfall forecast with snow to Savannah!!

Yes, in locations away from where the forecaster lives. That’s the key. Not necessarily exactly as you stated, but a “benign” winter. For example, literally every amateur forecast I’ve seen so far for this winter from those not living in the W, which includes just about every forecast I’ve seen, has the W mild/benign and the E cold along with AN snow. They’re all almost carbon copies of each other’s forecast. Their forecasts are much more predictable than what they’re trying to predict. This is influenced a lot by weenieism as well as the desire to get more clicks. Their bias dominates. I should emphasize that I’m talking about the amateur forecasters that I’ve seen so far. I’m not at all talking about objective amateur and pro forecasters without a hidden agenda who put the desire for accuracy ahead of weenieism and getting clicks.