John1122 Posted December 17, 2017 Share Posted December 17, 2017 Through 168 the trough is more N/S oriented on the Euro rather than the SW to NE orientation from the GFS. The SE ridge is differently oriented as well. Rather than centered over Florida like the GFS, it's being pushed off the Carolina coast. The cold is spreading slowly over the entire West. Probably going to be a warm week and then the cold will eventually ooze in behind the rain system. May be dry though, like the 0z run. Link to comment Share on other sites More sharing options...
1234snow Posted December 17, 2017 Share Posted December 17, 2017 By Hour 172 (afternoon on the 24h) heavy rain is over the western forum area and the 32 degree line has retreated to St Louis. Link to comment Share on other sites More sharing options...
1234snow Posted December 17, 2017 Share Posted December 17, 2017 By hour 186 Memphis has received about 9-10 inches of rain and the 32 degree line is still over St. Louis. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 I do not buy these runs that push cold across the Rockies from the east, especially from the southern Rockies. Will have to see it to believe it. These runs tip there hands early. Ther more west the trough (even by 20 miles) and the stronger the hp in the GOA behind it...the more it will dig. That razor sharp edge balances good and bad options for whatever reason. Hopefully the EPS will clear things up. Definitely a westward trend for the trough before it comes out....after the overnight runs spilled the trough more eastward. I still do not buy cold backing over the Rockies. It should spill down the front range and spread eastward. 12k peaks aren't just going to allow that to go southwest...line from JB Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 The trough east of HI and the EPO ridge argue that that energy gets kicked out earlier. I suspect that it will. The Euro plays games in the southwest...but it does have support from other operationals though not their necessarily ensembles. This run is not dry. Big swings. Link to comment Share on other sites More sharing options...
1234snow Posted December 17, 2017 Share Posted December 17, 2017 Hour 210 Arkansas finally turns over to heavy snow after receiving over a foot of rain. The rain shield never moves on this run for a few days. Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2017 Share Posted December 17, 2017 Looks like the Euro has joined the GFS with the slower spread of cold eastward. The ridge is positioned differently off the east coast but the result is the same. It hold the cold at bay. Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2017 Share Posted December 17, 2017 The highs will be in the 70s on Christmas day for most of the forum on this run of the Euro. Link to comment Share on other sites More sharing options...
1234snow Posted December 17, 2017 Share Posted December 17, 2017 500mb Vort and precip for hour 198 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 Runs that are replacing ridges with troughs every other runs....no trends....unless the trend it flipping. Link to comment Share on other sites More sharing options...
Kentucky Posted December 17, 2017 Share Posted December 17, 2017 ugh, bah humbug Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2017 Share Posted December 17, 2017 Definitely not a lot of day to day consistency but it looks like they are starting to see similar things. Not great news for us especially regarding snow for Christmas, but at this point you just deal with what you have to deal with and hope the cold can eventually make it here. I like our shot with 1050+ highs coming down. Looks like very -AO eventually, with a -EPO and +PNA. That should spell plenty of cold in the east at some point between Christmas and New Years. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 Cold seeping east from the front range of the Rockies westward across those mountains does not happen often. For cold to get into the west side of the Rockies it usually comes down that side of the Rockies or straight down the range. All operationals show "backflow" in the system. And I am highly suspicious of those solutions. The GEFS did not support the operational at 12z IMO. Let us see what the EPS does. Seems that the models are flipping every other run w the GFS flipping every run. Tough to say which model has been consistent. But eventually the hemispheric flow will send it East. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 The ensembles will be important today. The 12z GEFS and GEPS are pretty cold after Christmas Day. The EPS for the last four runs has been steadfast that Christmas Day(transition day) and after would be cold. We will see what 12z EPS says. The operationals are swinging in the wind. And I still think winter wx is on its way. The models seem to lose storms from days 5-8 and then regain them. With big highs in the Plains, that cold will spread out. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 You know, John....you mentioned 1989 many days ago. I have read some anologies to 83-84 as well. Those might be decent anologs w a whiff of 95-96 to finish off the season. I think the operational models are biased too far west at 12z. But if it comes down the front range and spreads eastward....many models are sending the mother load south. Big highs. Again, I am glad we are on this side of the Apps. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 Just looking at the 12z EPS, the cold indeed does not back southwest over the Rockies. It banks up against them in the Northwest and front range...and then comes east. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 Very cold run of the 12z EPS beginning late Christmas Day. Again, it has been very consistent with this look. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 All major 12z ensembles(GEFS, GEPS, EPS) now show impressive cold over the entire forum area beginning at a time centered around Christmas evening...earlier for western areas and later for eastern. As slow as that trough is moving, I will be surprised if it does not tap the GOM as the front trails into the Gulf. Now...back to basketball. Go Vols. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 You all give the 18z NAM a look. Seems to me it is weaker w the GOA high, east w the HI trough, slightly less amplified than the global models, and a tad more progressive. What do you think? That piece of energy is the clue. Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2017 Share Posted December 17, 2017 18z gfs is similar to 12z. Maybe a tick less deep into the west with the SW to NE stretched trough through 150. Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2017 Share Posted December 17, 2017 Trough may not connect with the trough that stretches all the way across the Pacific this run. Getting more PNA ridging into Western Canada and across Washington and Oregon by this time. Link to comment Share on other sites More sharing options...
PowellVolz Posted December 17, 2017 Share Posted December 17, 2017 12z Tuesday before the cold gets to Knoxville . Link to comment Share on other sites More sharing options...
ShawnEastTN Posted December 17, 2017 Share Posted December 17, 2017 I think the 18Z GFS looks a tad more reasonable than the 12Z. Definitely still doing weird things though. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 The 18z GEFS is sure cold for an ensemble run. The 18z NAM sure looked like it wanted to kick that trough out. The trends needed to move that trough on through were present on both the 18z GFS and NAM....trends matter. On an another note, Hoosier posted in the Midwest forum about a local met office talking about the big highs. The 18z GEFS was faster. My suspicion is that the cold air pours in and banks on the west side of the Apps at first. I like the trends at 18z. 83-84/89 are analogs now in play...kudos to John for bringing them to the board. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2017 Share Posted December 17, 2017 1 hour ago, PowellVolz said: 12z Tuesday before the cold gets to Knoxville . And it may be right. But I still need to see several runs before buying in...the ensembles were crazy cold. Might be that Christmas is warm followed by a memorable cold snap. Saw some freezing rain pop up on the 18z GFS. Remember the 12z Euro run that had freezing rain...I suspect that may show back up. Link to comment Share on other sites More sharing options...
Blackbearvol Posted December 18, 2017 Share Posted December 18, 2017 Would the lack of a snow pack up north hinder a deep sustained cold? Link to comment Share on other sites More sharing options...
John1122 Posted December 18, 2017 Share Posted December 18, 2017 24 minutes ago, Blackbearvol said: Would the lack of a snow pack up north hinder a deep sustained cold? It would to some extent, but the entire upper midwest and Canada is predicted to have a good snow pack by Christmas. The places in extreme southern Canada and the Dakotas that are snow free right now are expected to add 4-12 inches of snow in the next two weeks. There's 8-16 inches on the ground over Northern Minnesota and that region already. Those are the sources of our cold usually. The snow pack should be approaching the Ohio River by the time the cold is arriving here. Link to comment Share on other sites More sharing options...
John1122 Posted December 18, 2017 Share Posted December 18, 2017 The individual members of the Euro that show snow are fairly close to the Euro Op's snow track for the most part. Though there are a number of other individual members that have the same axis of heavy snow but it's more east on different members. Some show Memphis to Clarksville. Others Jackson to Nashville and others Chattanooga to Tri Cities. On almost every one it's narrow band, probably 150 miles wide with the heaviest part probably being 90 miles wide. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 18, 2017 Share Posted December 18, 2017 46 minutes ago, Blackbearvol said: Would the lack of a snow pack up north hinder a deep sustained cold? John pretty much covered it. Snow can definitely speed up delivery. Interesting thought though. Maybe the cold is feeding down the northern front range quicker because it has less resistance due to snow. Likely it is the pattern causing it. I honestly want to see what happens if a big 1060+ hp gets parked in the Montana or Wyoming flatlands. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 18, 2017 Share Posted December 18, 2017 16 minutes ago, John1122 said: The individual members of the Euro that show snow are fairly close to the Euro Op's snow track for the most part. Though there are a number of other individual members that have the same axis of heavy snow but it's more east on different members. Some show Memphis to Clarksville. Others Jackson to Nashville and others Chattanooga to Tri Cities. On almost every one it's narrow band, probably 150 miles wide with the heaviest part probably being 90 miles wide. Good info. Have to think ice is this equation somewhere. Again, I would not be surprised to see the Euro come back to the original ice storm from a few days ago. Those big highs hitting a near vertical conveyor belt out of the GOM. John, Flash and I were kicking this around the other day...is it the Euro or GFS or both that lose storms from d5-8 only to return to the same solution? If so, that ice storm may pop back up on a future run. Link to comment Share on other sites More sharing options...
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