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Everything posted by Carvers Gap
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Normally, it is bad form to be using the last slide of any model run whether it be ensembles or operational runs. I debated on whether just to put these in banter. Alas, we only live once. It is worth noting that the previous hours are actually colder. I am using these to demonstrate what modeling has been hinting at for several days. The first signs of the -NAO are actually showing up on the eastern coast of Greenland around 240. To me this makes a lot of sense as NAO sigs tend to return if they are seen earlier during winter. FTR, I am not saying this is going to result in wintry weather at lower elevations. It certainly could, and March has plenty of precedent for snow north of I-40. But that is a fairly stout block showing up in the LR. That is a pretty good conveyor belt for BN temps. I feel like I have said this 100x....we have seen this look before, only to see it corrode over time. That is certainly the likelihood with this set-up, but it is worth discussing, if anything just because it is interesting. This look has support from MJO plots and the SSW. The GEFS just goes bonkers with it.
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-NAO showing up on LR modeling. Mirage? Maybe. Both the GEPS and GEFS have it. The GEFS is actually trending towards a new LR look. We have been here before...so, we know the drill.
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Yeah, I watched the Weather Channel's LR forecast before I had access to wx models! I knew what time of day it updated. '93 was crazy, because they nailed it from so far out. I remember the snow for that being very fine, and light as that Saturday began. Then the hammer came down as the core came closer. As for the 70s, I lived in Knoxville and snow was plentiful. When it wasn't in the valleys, we would head to the Smokies to sled in the Chimneys picnic area.
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Let me go back and check. Now, of note 12z was a different run d10-15(more ridge in the east). The Weeklies are based off of 0z which was colder(flatter ridge in the East and more trough). Off the top of my head weak 3-6 are increasingly chilly w/ a -NAO developing and holding. The warm-up is likely due to the MJO rotation back through phase 7.
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12z Euro Weeklies hold serve and did not continue the warming trend, and were slightly colder.
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Man - that is rough! I was a child of the 70s to mid80s, minus two years in the purgatory (for winter lovers) known as Orlando, Florida. I lived some of my college days during the 93 blizzard. The 90s were barren compared to those times.
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One year we tracked a massive cold outbreak for 16 days on the GFS. Literally, it turned out to be a cold front passage which lasted about twelve hours. The 90s would have been the worst era to track 94-95, 96-97, 97-98, 98-99, and 99-00. I thought it might not snow again. We did have some random HUGE storms in there in NE TN. But overall, I can remember the grass having to be mowed on school playgrounds during the winter. And I am not talking like picking up leaves. I am talking mowing shin high grass. Now, it is on to the MJO. It is like an afternoon soap opera. It is full of drama. So, we are out of the really warm phases today. I bet a lot of you didn't know that - I didn't! We exited phase 6(barely) this morning on the CPC MJO plots. It has raced across 4, 5, and 6. We should see a rotation through 8, then it circles back into 7, and then maybe high amplitude 8 as we traverse March after the 10th. To simplify...hot, cold, hot, cold....wash, rinse, repeat. That IMHO increases the chance for a spring winter storm IF(stress) the precip can time w/ one of the incoming cold fronts. I don't think anyone is out of the woods regarding this(all elevations). To be clear, modeling is woefully benign at 12z. I don't see a threat on modeling. But all winter, we have seen modeling correct towards the MJO plots. I think that will occur as we move onward. It will be interesting to see if the Euro Weeklies continue to trend warmer in the LR(the were cold and then cold-ish)
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Fall/Winter Banter - Football, Basketball, Snowball?
Carvers Gap replied to John1122's topic in Tennessee Valley
Vols. -
They tend to go to Asia more often. If we get a dump of cold air here, it often goes West as Holston notes. Cold air masses heading south like big continents. The Rockies tend to bank cold, but the Plains and front range are the center of the continent so that makes sense. SSWs will absolutely wreck modeling in the LR, so I am pretty guarded w/ the timeframe of Feb 25-March10. Could get wild during that time frame if the cold dumps into the Lower 48...just depends where it goes.
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One further note, those big highs are often the product of SSW events. They will dump into the west about 75% of the time and then head eastward. If they every head east first(this looks west), look out.
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Well, in February I pretty much want cold. I don't want spring in Feb.
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To thread the needle we want to see one of those big highs sliding with a low pressure along the Gulf Coast. So, one of the ways we identify winter wx windows is to find a big high. How quickly does it slide to the east is important. How strong the high is also important. Most cold shots are not holding for long east of the MS, so we really are just looking to time-up something. We want an active jet stream for this to occur and shorter wavelengths. The timeframe around the 24th is a possibility.
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Surface pressure during winter is usually high if the temperature is cold. Pressure at 500mg is a different story. I use surface pressure to see if the cold is slipping under high pressure aloft. 1050 is a BIG high. We know the cold shot is significant if it is generally above 1040. Other globals have it further north. That type of intrusion on the GFS(and it has signaled falsely multiple times this winter) would be significant, but well within climatology.
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Just as an example. This is way out there so big boulders of salt.
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Big highs like that are trouble during late February from my experience. The Canadian has a similar set-up, but the cold doesn't drive as far to the south. Those are big time features, and would highly likely have a big storm sitting right on their southern edge if true.
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1056 hp rolling through the Plains d8-10 on the GFS. Yes, it is the GFS. That said, that is a monster. The MSLP anomaly is expansive.
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Fall/Winter Banter - Football, Basketball, Snowball?
Carvers Gap replied to John1122's topic in Tennessee Valley
That is a trip. It is going to have to up its acronym game. We may eventually need a secret code to certify that we are indeed humans. It won't take much for that to get a lot better. -
I have started a new thread dedicated to just talking about various aspects which affect our winter weather. Feel free to jump right in. I don't really like the thread title, so if one of you creatives have a better suggestion, please fire away. Anyway, I thought we might begin with the PDO. We can keep that thread running most of the off season.
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Now, south facing walls of buildings are super interesting micro climates as are urban heat areas. I have a fig planted in my backyard against a brick wall which faces south. The climate along that wall is probably most similar to central Georgia due to the heat reflected from the brick during the day and the heat which the brick gives off at night. Loosely termed, it is like a very weak oven. My location is agricultural zone 7a. But that wall area is probably 8b. The first stuff to bloom in my yard is usually along that wall or the south facing slopes of my front yard. I have stuff on that wall which didn't die back during the hard freeze of December. I started learning about figs through the Italian Garden Project which is documenting how Italian Americans grow Mediterranean fruits/vegetables in New York, New Jersey, and Long Island especially. They grow lemons, figs, persimmons, and mediterranean vegetables. They bury their fig trees during winter. South facing walls are critical. Pretty fascinating stuff. So, temps might be 5-10 degrees warmer in those areas which you mention.
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If there is any term I truly hate in professional development, it is "deep dive." When I hear that term, it makes me want to dive under the table. So, why am I using this term today....I am sort of making fun of the term. Anyway, if you have a better term for dialoguing (another term I truly an uncomfortable with) about various aspects of global weather such as the PDO, AMO, IO, AO, NAO, SOI, MJO, PNA, EPO, QBO etc....I am open to suggestions. Anyway, I thought maybe we could fire up a thread to learn. I thought of this thread idea, because one aspect of my seasonal forecast that I forgot to include was the PDO. And the PDO may well have been partly driving the bus this winter(and the past several in North America). Anyway, here is an article(second link) I am working through. So, what do you all know about the PDO, and maybe how has it been impacting NA weather? I "think" the cold phase PDO is connected to Nina ENSO states as cold water is along the Pacific NA coastline and water water is in the north central Pacific. The warm PDO is the exact opposite. I am not ignorant not he subject(I do lack overall expertise on this), but I truly need to learn more about it, as I think the warmer anomaly of water over the north central Pacific is pulling the trough into the west. And the physics of that is what I am trying to understand! How is the warm water in the north central Pac pulling that trough into the West(or is it)? https://legacy.climate.ncsu.edu/climate/patterns/pdo (primer) https://journals.ametsoc.org/view/journals/clim/30/9/jcli-d-16-0376.1.xml (working through this article currently)
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Nashville's low Saturday AM is 23...let's hope there isn't a ton blooming.
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Other than some daffodils, nothing blooming here that I can see. I hope things don't start getting going too quickly. The 12z EPS was not warm after d10. It must feel like it was outdone by the Happy Hour GFS yesterday. It wasn't "hold my beer" cold, but it was chilly. This MJO trying to hang out it 8 makes me super cautious. It won't surprise me to see modeling flip colder at some point if that MJO is legit. What may happen is it rotates into 8...back to 7...back to 8. That seems more reasonable. The low here Saturday is supposed to be 21. That will nip most blooming things here pretty badly.
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Spring is clearly on modeling today in the LR, but Saturday night will be bitterly cold before we begin to make the climb. I still think we see a very sharp cold shot later in the month or early March. The 12z Euro was trying to cook some mischief up today. For now, I think the climb to spring begins in earnest after this weekend. One thing to be wary about, maybe about half to 2/3 of modeling stalls the MJO in phase 8. If that happens - cold. Also, I am seeing some hints the NAO is going to fire. Also another thing to be wary about, during 2018 when the SSW occurred...modeling flipped on a dime (literally went from warm to very cold in one run...and then stuck the landing from 16 days out). Spring being on the way is not exactly a difficult call on my part as days are getting longer and this week is going to be WARM right before we cool back down.
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The 18z GFS rarely disappoints, and tonight was no exception as it tried to build a glacier in the LR. Alas, it is the LR and it is the GFS at range. But fun run.
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