Carvers Gap

Growing confidence that a signifiant pattern change is inbound. It is NOT a lock. But if you think we are the only folks talking about this, you would be in error. This is the 3-4 weeks CPC forecast which was released yesterday. That is pretty bold outlooks at the range! Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks NWS Climate Prediction Center College Park MD 300PM EST Fri Feb 24 2023 Week 3-4 Forecast Discussion Valid Sat Mar 11 2023-Fri Mar 24 2023 La Niña conditions are currently present with below average sea surface temperatures (SSTs) across most of the tropical Pacific Ocean. Low-level easterly wind anomalies were evident across the western and central equatorial Pacific Ocean, while upper-level westerly wind anomalies were observed over the central and east-central equatorial Pacific. The Real-time Multivariate (RMM) Madden Julian Oscillation (MJO) index indicates a robust eastward propagation of the intraseasonal signal shifting from the eastern Indian Ocean to the Pacific over the past 3 weeks. Dynamical model MJO index forecasts generally show a weakening signal during Week-1, followed by a re-amplification of the index over the Pacific during Week-2. The Week 3-4 Temperature and Precipitation Outlooks are based primarily on operational dynamical guidance including the GEFSv12, CFSv2, ECMWF, JMA, and experimental guidance from the Subseasonal Experiment (SubX) multi-model ensemble (MME) prediction systems, with additional considerations for Madden Julian Oscillation (MJO) states, the El Niño Southern Oscillation (ENSO), the ongoing sudden stratospheric warming and other high latitude variability as well as decadal climate trends.. A blend of the CFSv2, ECMWF, and GEFSv12 500-hPa height pattern forecast, plus a small contribution from the Multivariate Linear Regression (MLR) height forecast based on the RMM index, La Niña, and decadal trends, predicts a broad anomalous trough over the central and eastern contiguous U.S. (CONUS). Weak positive 500-hPa height anomalies are forecast over the southwestern coast of CONUS. Anomalous ridging with above-normal 500-hPa heights are predicted over the Aleutians and Mainland Alaska, while below-normal 500-hPa heights are forecast over the Alaskan Panhandle. Most dynamical guidance features near- to below-normal 500-hPa heights over the Hawaii islands. The Week 3-4 Temperature Outlook anticipates a major pattern change leading to widespread colder than normal temperatures over much of CONUS, except for Florida Peninsula where elevated probabilities of above normal temperatures are indicated, consistent with a forecast troughing pattern over the central and western CONUS. The highest probability of below normal temperatures (80-90%) are forecast over the Upper Mississippi Valley beneath a strong anomalous troughing. Elevated probabilities of above normal temperatures are favored over northwestern Mainland Alaska and the Aleutians, while a tilt toward below normal temperatures are likely across eastern Mainland Alaska and the Panhandle, supported by decadal trends and most dynamical model temperature forecast tools. The Week 3-4 Precipitation Outlook favors above median precipitation over the Pacific Northwest and toward the Northern Rockies to the western Northern Plains, consistent with most of the dynamical precipitation forecast tools. Increased probabilities of above normal precipitation are also favored for the eastern CONUS in association with the troughing predicted over the region. Enhanced probabilities of below median precipitation over parts of the Southwest is supported by most model guidance. Ridging over Alaska favors increased probabilities for below normal precipitation across the State. Above-average sea surface temperatures are currently observed in the vicinity of Hawaii.The SubX MME probabilistic temperature forecast favors above average temperatures over Hawaii during the Week 3-4 outlook period. Dynamical model guidance from the SubX MME shows increased probabilities for above median precipitation over Hawaii with strongest probabilities over Lihue.

If I was a squirrell and saw the LR ensembles this afternoon, it would make me want to go get a crap ton of acorns to survive the winter....I mean spring.

Wyoming road crews are struggling to keep I-80 open. 4' drifts reform right after they open them. The southern coast of Oregon got a very rare snow storm. Since we are basking in the warmth(well predicted by models!), we can enjoy some sights out West. While road closures are not rare in WY, the extend and duration are eye opening. Great photos in this thread of the recent storm in Wyoming. Slammed! Likely some severe runoff issues during April/May/June. \https://www.sweetwaternow.com/wyoming-continues-to-dig-out-of-recent-snow-storm/

Interesting. Yeah, that is pretty bold given that is 8 days out. The 6z GFS is a cutter for here(lost the Miler A look...we can blame WJHL). LOL. I feel less optimistic about that storm (for MBY) than I have. The ensemble indeed looks more like the 0z Euro. My gut says this goes to our west. The Canadian is a full cutter. For whatever reason, I like the window for TRI between March 10-20. That is awfully late for a winter storm, but that window has nice blocking and is cold. Is it cold enough? IDK at this range.

If I remember correctly, Chattanooga broke its all time record high yesterday from 1879. In Casper, WY, they broke one from 1894. Some areas of WY are flirting w/ some old snow records. https://capcity.news/community/weather/2023/02/23/cheyenne-breaks-nearly-130-year-old-record-cold-temp-overnight/

This is the GEFS ext from this evening....We have seen this look before, and it is possible that there is some bias across modeling. EPO/NAO couplet is the sauce if we can somehow find it. Keep in mind that BN temps during March have to be REALLY below normal in order to get snow. If somehow the PV was trapped under that....(not seeing that just yet) but man.

Likely to the last question. Models today are trending colder than yesterday. Still a sold couple of weeks from any meaningful pattern change potential. Lots could change, but the ensembles now have it. So, the cold solutions have moved from the Weeklies to the global ensembles. The potential is there for very cold temps. The CFSv2 had temps twenty degrees below normal. Fingers crossed.

Western half of the state did well in January. Yes, E TN and La Nina winters just don't mesh well. To be fair, some great winters have been weak La Nina's BUT they have a negative QBO component(didn't have that this winter...14 month cycle is in our favor next winter though). We need that coastal component to score, and coastals have been largely absent this winter.

Same. I am going to enjoy looking and tracking this...but 72 hour rule is a good rule at this range in terms of how serious we take it.

This is an example of what we are looking at. This is not the Gospel. We have seen this before and it not materialize. So, again, just enjoy discussing the weather.

Doubtful. Sometimes that can happen w/ Jan/Feb, but pretty rare for March. I think the first week of March should be warm enough to prevent that from occurring, even w/ a potential winter event for week one. I won't discount it, but I don't see massive cold anomalies on that order. It looks cold, but not extreme. There are some extreme runs, but not consistently. It would have to go wall-to-wall to beat Feb as the lengthening of days will eventually rule that roost. Weeks 2-4 of the Euro Weeklies (hot of the press) have a very cold pattern. Early in week 3, departures are ten degrees BN which is significant on an ensemble run...

I would encourage everyone to enjoy tracking, and not to get overly invested in a d8-10 storm. We are simply discussing a storm at range. It is highly likely storms at this range don't materialize. And it is March. But we are going to be discussing and track, so be ready....and don't get too invested at this range. Thanks to Holston for creating the thread. I doubt I have seen the last flakes of snow IMBY. March is probably not going to be worse than any other month this winter - LOL. So, the bar is set very, very low.

Holston, definitely time for a March/April/May thread.

Good overnight discussion. Definitely tracking cold and/or winter wx at this latitude during spring is fraught with disappointment. So, know that before jumping in..... It wants to rain at this latitude for all but about 6-8 weeks per year, and March isn't one of those weeks. But, March has delivered some big snows on an irregular basis. I still want to see the LR window get inside of d10, and weeks 2-4 of March are not there yet. Either way, I am going to start mulching and getting the garden ready. Cold or not during March/April/May....spring is going to show up sooner than later.

For kicks and giggles, the GEFS(ext) control run. Is it yet another mirage? Possibly given recent misses. Hopefully, we don't get all dressed up for nothin'...William Wallace

The 18z GEFS is textbook SSW. It is about 2-3 weeks after the main strat warming. I think (famous last words) the trough gets kicked eastward. Honestly, I am not a huge fan of cold springs...so I am not overly fired up about it! Cold springs equal bad early growing seasons for gardeners. I think we will see a short spell of the eastern ridge hooking into the trough, but eventually incredible amounts of HLB overwhelm the pattern. Still in the range where it could be a mirage, but this looks decently legit at this range............If true, major changes coming in our weather pattern.

It is a rare event. Those types of wavelengths have my interest.

If someone want to start a March, April, May spring thread....go for it. Preliminarily here is my forecast for spring Temps: March: normal to BN April: BN May: BN Precip: AN all months Snow: Potential for multiple heavy snows in the Apps. Crapshoot int they valleys but not a zero chance deal. Could be rough for people through-hiking the Appalachian Trail. Note: I will give models another week before finalizing this.

Right now I am trying to find a "warmest model" for March....and I am having trouble finding one. The GEFSext and CFSv2 are cold. They may not be snow cold. But they are certainly loaded with cold rain and likely elevation snows. When I see the map in California, that tells me that one good amplification can send cold into areas where it usually isn't at this time of year. Cali is the ying to our yang.

Well, March 5th is 13 days out right now...so we have a ways to go. The LR continues to look pretty much awful(cold) for a lot of March. For kids in spring baseball, soccer, and track...that forecast pretty much is the pits.

Man, the winter storm along coastal areas of southern Oregon and Northern California is going to threaten records of all sorts - snow, record lows, etc. Go read the AFD for Port Orford, Oregon. It is crazy what is going on. Seeing Southern California w blizzard warnings (foothills of LA) is mind bending. What a crazy, crazy, crazy look when you look at all of the WSWs and WWAs posted in some not so normal places in California. Amazing stuff. Don't miss it. You won't get to see that often on a wx map. BTW, the record highs we either threatened or breached today were from 2018....take a look at March of 2018.

Yeah, teleconnections are nasty for the last 20 days of March. I still want to see if they verify. Lots of mirages of late have not transpired. But that is one chilly pattern lurking if it does. I see three scenarios right now: 1. -NAO stays over Davis Straits, and it gets cold here. 2. The -NAO shifts to the Hudson Bay, and the EPO ridge pops - very cold and stormy here. 3. The -NA) shifts to the Hudson Bay an the EPO ridge stays off shore just enough to send the cold into the nation's mid-section and front range of Rockies....different set-up to today's weather but same outcome(warm east). Right now I strongly favor options 1-2. Nino is gonna have to win-out for that to occur. If options 1-2 occur, the storm track will be vastly different than the past three months with lots of systems to our south. We will see. This look is kind of a long, last gasp of winter.

Both the 12z CMC and 12z GFS looked decent for middle TN on March 4th - Holston mentioned it. At the 10 day range, that is about all I would comment on it. Likely will be different next run.

Still there on the 12z GFS and CMC. May have even moved up a bit. I just don't talk much about it as details will be sparse at this range. I usually will set a window, but won't talk specifics until around d7 if it materializes. The 12z suite so far show some potential, but that is a LONG way out there.

Rare winter storm warnings for the Southern Oregon Coast and Northern California Coast! Coos Bay and Port Orford are under WSWs. Blizzard warnings are also up in the mountains immediately outside of Los Angeles. RARE but not unprecedented. I don't remember seeing blizzard warnings in the mountains above LA. Take a look at the advisor map for California. I have not changes to my thoughts this point about weeks 2-4 of March. The block looks real.