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Srain

Central/Western Summer Medium/Long Range Discussions

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Man, first time venturing onto this forum (Philly-brah)...Its in LALA land, and I can't see the precip maps, but that looks like on helluva blizzard for MN on the day 8-10 EURO. Christ. 

 

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Impressive run to say the least.

 

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Like you did mention though, it is a nine day forecast...

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0z Euro still putting together a show for the Plains around day 8. Big differences from the GFS, which tends to break ridging in the west, cutting off part of the trough in the southwest, and the arctic air trying to dive south is deflected northeast.

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Increasing agreement between the latest 00z suite for some sort of severe weather setup around 6-7 days out, the Euro and GGEM have had a much larger, long wave trough ejecting while the GFS is more fragmented, although all three agree that a substantial warm sector will likely be in place for anything that does eject towards the MS Valley.

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There does appear to be some increasing consensus that a full latitude trough will develop across much of the Western and Central North America Regions. Water vapor imagery clearly depicts this advancing trough heading E across the Pacific and it has the potential to bring a significant Winter Storm across our Region as disturbances ride S in a strong N to NW upper flow and embedded disturbances from the Eastern Pacific as well as a bit more of a return of Gulf moisture combine across the Desert SW/Southern Rockies into the Plains allowing higher elevation snow that may extend into the Plains and Upper Mid West in the cold sector and strong to severe storms in the warm sector ahead of the advancing Arctic boundary. The time frame of interest appears to be the 17th-20th of November. sat_wv_hem_loop-12.gif

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Increasing agreement between the latest 00z suite for some sort of severe weather setup around 6-7 days out, the Euro and GGEM have has a much larger, long wave trough ejecting while the GFS is more fragmented, although all three agree that a substantial warm sector will likely be in place for anything that does eject towards the MS Valley.

Yeah hopefully I'll get around to typing up something more substantial/starting a thread tonight, but this one's really got me interested.

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Yeah hopefully I'll get around to typing up something more substantial/starting a thread tonight, but this one's really got me interested.

 

I will be looking forward to your post/thoughts.

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Yeah hopefully I'll get around to typing up something more substantial/starting a thread tonight, but this one's really got me interested.

Looking forward to it. I'm pretty excited/concerned and I'm usually on the conservative side with these fall events lol

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GFS, Euro, CMC all toying around with some wintry weather for the central and southern plains on Friday.

Sam, I am working on a forecast/analysis regarding the upcoming Medium and Long Range Pattern change for our Region and will await some additional data before posting some thoughts. What we are seeing in the Medium Range is a transitional pattern from that of a zonal flow where record high temps were set today across many locations in Texas. It does appear the first in what may well be a series of at least 3 cutoff 500mb low close off and meander slowly E in the Southern Stream. It is noteworthy that the AO decline has started and we are see in rather strong indications of a PNA Ridge developing as well as some indication of a W based NAO. Typically when the Nothern and Southern streams become active in tandem, our Region transitions to a colder regime and snow cover increases across the Plains lending to less air mass modification as the pattern is rolled forward. It does appear that the Desert SW/Southern/CCentral Rockies including Northern Mexico will see our first significant Winter Storm of the season starting this Thursday extending into early next week.

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The trends over the weekend certainly do paint an interesting pattern with our first true SW cutoff low of the season now depicted to develop near San Diego and slowly ejecting E and opening up over Texas/Oklahoma late this coming weekend. The general theme via the 00Z guidance suggest a strong Canadian air mass with a 1050mb+ high pressure cell dropping S from Canada and settling across the Southern Plains Wednesday into Friday as some modification occurs due to lack of snow cover across the Central Plains.

 

What is different from our last cold shot is this likely will not clear out the Region as clouds and over running precip develops in a SW flow aloft from a developing noisy sub tropical jet streak near 140 kts develops as that upper low to our W deepens and eventually closes off before slowly sliding E over a chilly shallow cold air mass at the surface that allows a backdoor front to slide W as far as Flagstaff/Tucson, Arizona Thursday into Friday. The Northern stream also looks somewhat active as strong disturbances ride E across the Central/Northern Plains keeping cloudy conditions and less in the way of daytime modification as cold air advection continues from the N. Such a pattern suggests heavy higher elevation snowfall in excess of a foot is possible across the Southern Rockies extending as far S as Ruidoso/Cloudcroft, New Mexico and possibly extending into Northern Mexico. Over running precip should develop beginning next weekend and depending on just when the SW upper low ejects, a Coastal wave of low pressure may develop near Corpus Christi and head ENE along the NW/Central Gulf Coast providing additional lift and a heavy rainfall potential along the Upper Texas and Louisiana Gulf Coast late Saturday and possibly extending into early next week depending on the eventual evolution of a secondary Western trough/500mb low ejection from the Southern California/Northern Baja Region.

 

Chilly surface temps in near or just above freezing across portions of Central and Northern Texas could offer some p type issues mainly in the form of either very cold rain or a freezing rain/sleet wintry mix. Further N and W snow looks likely across the Panhandles of Texas and Oklahoma and New Mexico and rain possibly mixed with snow could fall across portions of Central Oklahoma. It is also noteworthy that the AO has began to decline from a very positive state (4+) toward at least a neutral state as well as the NAO and the are indications that a pattern change is developing across the NE Pacific to that of a +PNA Ridge along the NE Pacific extending into Western Alaska and a blocking pattern across the North Atlantic. A Polar Vortex anomaly is beginning to show signs of developing across Canada near Hudson Bay as well that may allow for additional short wave energy to drop S into the Northern Plains. If we begin to see snow develop across the Plains as the Northern stream storm track drops S into the Northern and Central Plains, less Polar air mass modification begins to be an issue as disturbances drop S along the West Coast and develop to our W and SW as some of the longer range guidance is now beginning to suggest. There are also indications that the Sub Tropical Jet will become active as it brings Pacific moisture from convection noted E of the dateline.

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Very interesting solution 144 hours+ out for much of Texas involving a couple of potent cold fronts and a SWUS cutoff low. A perfect alignment of features could lead to some very anomalous freezing rain or even snowfall like yesterday's 12Z ECMWF and today's 00Z GFS. Model trends as of late (00Z ECMWF, 12Z GFS) have moved the lift with the SWUS cutoff further to the west during the time period the cold air is occupying Texas, but there is lots of time to watch the models throw out solutions before we can start getting a better picture of what is going to happen in more detail. Regardless, it looks like a particularly dreary weekend may be in store with cold and cloudy/drizzly conditions.

 

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Ha, just as soon as I said the models were trending west with the SWUS cutoff, the 12Z CMC and ECMWF bring it back to the east, bringing lots of overrunning over a very cold airmass. Perfect example of the volatility of longer range model forecasts.

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Some of the 00z models (as well at the 12z) suggest increasing potential for a return to strong western troughing as we move into the first few days of met winter. Models appear consistent in developing another strong/highly amplified block over the Aleutians and then breaking down with a flood of jet energy crashing south/east into the West Coast on the east side of the ridge. What happens after this is obviously up in the air, but I wouldn't at all be surprised if another strong system or two ends up ejecting out of this pattern come the first/second week of December.

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Yet another interesting pattern developing in the medium/longer range operational and ensemble guidance. The European suite suggest a deep cold core low with temperature departures of 20+ across the Pacific NW into the Great Basin/Northern/Central Rockies extending into the Northern half of the Plains. Another Arctic boundary should drop S into the Southern Plains next Thursday/Friday that may set the stay for strong storms in the warm sector and over running wintry precip across the Southern Rockies into the higher elevations of the Desert SW. Should the stronger slower solution evolve, a very chilly pattern with over running precip over the shallow cold air mass at the surface could set the stage for another Winter Weather event across the Southern US next weekend. There remain a lot of details to iron out, but the pattern does raise an eyebrow as we near Meteorological Winter across our Region.

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Op GFS verbatim to warm for Winter fun IMBY, but I think we're definitely close enough with a coarse res global beyond resolution chop for some optimism.

 

 

Cold w/o snow or ice just kills sub-tropical plants like palms and citrus that brave people try to grow in the mid-latitudes.

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For the past 3 to 4 cycles, the Day 8+ analogs have painted some memorable dates in past years for our Region. It will be interesting to follow the progression of this upcoming pattern in the days ahead.

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The analogs show 12/20/1990. The upcoming pattern in 3+ days is quite similar to December 18-19, 1990. Hopefully, my area stays above -24F this time.

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New Euro has a nice cool down, but warms SETX well above freezing at the end of the 10 day run before the next predicted significant rainfall. (Verbatim just misses us to the North, the really heavy rain, but 9 days out...)

BTW, that is potentially a significant FUN-derstorm signal on the free Euro 850 mb winds/500 mb heights if there is any instability at all.  With 12Z  forecast at 216 hours temps pushing into the 60sF well into SETX (and as far East as Arkansas and Mississippi...) instability could be present.

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With regards to the southern plains, there is a great interest in the weather at the end of the week, but the most anomalous conditions/cold might be even further out, more towards mid-December. Depending on how the Alaskan block breaks down, there is the potential for lots of very cold Siberian air displaced into western Canada to drop south (or not). Who knows at this point.

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With regards to the southern plains, there is a great interest in the weather at the end of the week, but the most anomalous conditions/cold might be even further out, more towards mid-December. Depending on how the Alaskan block breaks down, there is the potential for lots of very cold Siberian air displaced into western Canada to drop south (or not). Who knows at this point.

Yes, mid-late December is a timeframe I'm watching with great interest as well. It looks to me like the coldest air in many years seems to want to hang around this side of the globe a little more than in years past. If this continues, which I see no signs of it stopping, it could be an extreme winter here in the central US. Maybe top 5 cold here in Oklahoma by the time its over.

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One event I keep hearing tossed around is that of December 1983, although much of that has been from Joe B, so take it for what it's worth.

 

With that being said, mid-range ensembles keep the cross-polar regime in place for over a week. Hard to argue against a prolonged period of anomalous cold with that type of signature.

 

f168.gif

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One event I keep hearing tossed around is that of December 1983, although much of that has been from Joe B, so take it for what it's worth.

With that being said, mid-range ensembles keep the cross-polar regime in place for over a week. Hard to argue against a prolonged period of anomalous cold with that type of signature.

f168.gif

Lol. I didn't want to be as extreme as to say 1983-84 but it would be crazy to experience that here in Oklahoma and looks eerily similar. From my understanding that's a top 5 cold winter here. Anxious to see how the rest of this new cold season plays out!

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The longer range ensembles continue to advertise another Arctic air mass dropping S from Canada just prior to the Christmas Holiday period.

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Mighty impressive pattern via the EURO Ensemble 500mb and after seeing the various operational and other Global ensembles in the medium/longer range, it certainly raises an eyebrow and memories of 83 and 89 when a somewhat similar pattern developed catching many off gaurd as they headed away for the long Christmas Holiday period to return to siginicant damage from bursting pipes and property damage from prolonged sub freezing temperatures.

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