Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 6

[Srain]

The 500mb charts are suggesting a classic omega blocking pattern darn close to a McFarland signature. Over the past 50 years of watching weather patterns in Texas, the computer models do not handle shallow dense cold air well at all. I seen the GFS and Euro be way too quick with retreating the cold once it arrives. The ensembles are suggesting once the pattern locks in, the 500mb flow is very favorable with reloading re enforcing shots of Arctic air from the Canadian Prairies with the origin of the high pressure cells in Siberia and the N Pole. There are indications that the sub tropical jet will be noisy which suggests clouds with embedded disturbances dropping S and rounding the base of the mean full latitude trough. If the -NAO is strong enough, the general troughiness locks in across the Inter Mountain West and the Great Plains. Add to that the potential of any NW Gulf Coastal low/wave development, then you have the recipe for all sort of winter weather issues. We came damn close back in November to a big icing problem when a coastal developed after the Arctic air arrived and it rained moderately at 35F here in Houston. Those 'finer details' cannot be determined beyond 2 to 4 days...if then.

 

[Portastorm]

06Z GFS operational is not nearly as cold as the previous run. Nothing severe or historic in its temp progs for Austin. Lowest temp is 25 during the cold snap and well above freezing every afternoon.

The progged 500 mb pattern varies slighy by model. But one thing they consistently have in common is fast zonal westerly flow over Texas with very little in below normal heights.

Funny how you don't mention the GFS 0z op run for Austin which keeps the city below freezing for more than 24 hours around New Years. Nothing like cherry picking whatever model runs fit your bias.

[Quixotic1]

The 500mb charts are suggesting a classic omega blocking pattern darn close to a McFarland signature. Over the past 50 years of watching weather patterns in Texas, the computer models do not handle shallow dense cold air well at all. I seen the GFS and Euro be way too quick with retreating the cold once it arrives. The ensembles are suggesting once the pattern locks in, the 500mb flow is very favorable with reloading re enforcing shots of Arctic air from the Canadian Prairies with the origin of the high pressure cells in Siberia and the N Pole. There are indications that the sub tropical jet will be noisy which suggests clouds with embedded disturbances dropping S and rounding the base of the mean full latitude trough. If the -NAO is strong enough, the general troughiness locks in across the Inter Mountain West and the Great Plains. Add to that the potential of any NW Gulf Coastal low/wave development, then you have the recipe for all sort of winter weather issues. We came damn close back in November to a big icing problem when a coastal developed after the Arctic air arrived and it rained moderately at 35F here in Houston. Those 'finer details' cannot be determined beyond 2 to 4 days...if then.

This -NAO looks right now to be strongly west based. That's typically a signal for air masses dropping into plains before slowly moving east.

[Srain]

This -NAO looks right now to be strongly west based. That's typically a signal for air masses dropping into plains before slowly moving east.

Yes Sir. Almost like the upper pattern we experienced in mid November, but without the extratropical super storm in the Bering Sea. What is giving the OP Global models fits is the eventual outcome of the big storm wrapping up in Canada and where it eventually ends up. The Euro weeklies yesterday suggested a PV anomaly near Hudson Bay with a 498 decameter center. That is a stout signal in the day 12-15 range from the weeklies and something to monitor as we get a bit closer to next week.

[Srain]

Now let's get back to talking weather. Looks like a strong front arrives on the 27th with another stronger surge of chilly air around the 30th with a possible winter storm with a southern tracking system and an Eastern Pacific disturbance crossing Mexico the beginning of January.

[Quixotic1]

00z gfs and para blast entire state. Central Texas (Austin this means you) gets over a foot. If we border cold and keep the STJ active we are in really good shape.

[Srain]

Happy New Year Texas gang...

 

 

 

[DFWWeather]

Happy New Year Texas gang...

 

12202014 DFW GFS Day 8 to 16 dfwgfsb.png

 

 

If I'm reading that correctly, it has DFW at or below freezing for nearly 7 days. Brrrr!

[Portastorm]

00z gfs and para blast entire state. Central Texas (Austin this means you) gets over a foot. If we border cold and keep the STJ active we are in really good shape.

I didn't quite see that from the 0z GFS but it does look like at least .60" of frozen precip in various forms for Austin. That would easily be enough to shut the city down for several days.

[aggiegeog]

Happy New Year Texas gang...

12202014 DFW GFS Day 8 to 16 dfwgfsb.png

12202014 AUS GFS Day 8 to 16 ausgfsb.png

12202014 GFS IAH Day 8 to 16 iahgfsb.png

The expected Arctic outbreak is looking like a dream scenario. I will sure be keeping a close eye on those Alaskan 500mb heights, if they get to the 560s I could see highs around freezing here and 570+ and things could get bad around here. Needless to say nat gas prices are about to skyrocket, wish I was in the market.

[1900hurricane]

One run of one model ten days out does not a medium range forecast make, but dang does the 00Z ECMWF look set up to do something interesting.

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[Srain]

The Global operational and ensemble guidance is in good agreement with a quick hitting trough and front clearing our Region on Tuesday. The longer range ensembles are suggesting once we get cold late next week it will likely linger in the first week of January...if not longer.

[bubba hotep]

The Global operational and ensemble guidance is in good agreement with a quick hitting trough and front clearing our Region on Tuesday. The longer range ensembles are suggesting once we get cold late next week it will likely linger in the first week of January...if not longer.

 

I really liked the look of the various ensembles today.  The Euro ESP had a good number of members that seem to support the GFS like winter weather scenario across Texas heading into the New Year.  I am still nervous that without a disruption of the vortex the cold will be transit and we will warm back up beyond the 1st week of January.   

[DFWWeather]

I disagree with this mornings FWD AFD. The forecaster claims the Tuesday cold front is Pacific in origin, but looking at the GFS and ECMFW, the airmass is clearly Canadian in origin. The models have trended further west with the trough with a bigger dumping of cold air into Texas since last week. The temperatures should have no problem reaching freezing despite wind and cloud cover on Wednesday morning at DFW given the H85 temp profile on both models. Furthermore, depending on cloud cover, Thursday morning could reach 26°F-29°F across DFW. Given the GFS partial thickness of nearly 534 dm and light QPF, might be some flurries?

[DFWWeather]

BRRR! Especially CMC on the right.

 

[Srain]

Big quick shot of cold air coming on the 23rd as the Plians storm wraps up into a powerful cyclone .ear the Great Lakes into Canada. Convection near Hawaii builds a big Western Ridge that eventually ridges into Alaska as the Canadian cyclone retogrades to near Hudson Bay. The operational and Global ensembles suggest a big 1050 to 1060mb Arctic High drops across the N Pole from Siberia and pushes S across the Canadian Praries and pushes into Montana and Wyoming near the 30th ushering in a very strong front arriving by New Year's Eve. There continues to be some indications that a Southern tracking storm arrives a day or two later with some potential of a Coastal low/wave developing along the Lower Texas Coast after the cold air is entrenched across our Region.

[aggiegeog]

Some models beginning to see the snow potential for Tuesday. It will probably be less than an inch for all but the Panhandle, though flakes are possible generally north of I-20.

And to inject some NM discussion, it looks like tomorrow could bring snow to much of NM with 6-12 inches in the mountains of northern NM.

Once we get the cold air entrenched after Christmas this will be the type of storm that will provide constant opportunities for snow for us here. They are hard to nail down from very far out, but they keep popping up as the time nears.

[Quixotic1]

Gonna call it like I see it:

The good: EPO looks to go solidly negative and remain there.

The meh: AO and NAO flip flop.

The bad: the MJO seems to be trying to destroy us. Weak amplitude almost ensures another repeat of the last wave. 4-6 into the COD.

This is not a winter cancel, however, I'd be very surprised if we have anything close to a legendary winter anywhere country wide. The comparisons to 76-79 are probably going to look silly.

My gut tells me that atmospherically speaking, we are in a very inert mode and there's nothing really there to change things. When people start talking about ssws in late January, I worry.

This Niño is not acting much like one.

Nobody will be happier if I am wrong.

[DFWWeather]

Gonna call it like I see it:

The good: EPO looks to go solidly negative and remain there.

The meh: AO and NAO flip flop.

The bad: the MJO seems to be trying to destroy us. Weak amplitude almost ensures another repeat of the last wave. 4-6 into the COD.

This is not a winter cancel, however, I'd be very surprised if we have anything close to a legendary winter anywhere country wide. The comparisons to 76-79 are probably going to look silly.

My gut tells me that atmospherically speaking, we are in a very inert mode and there's nothing really there to change things. When people start talking about ssws in late January, I worry.

This Niño is not acting much like one.

Nobody will be happier if I am wrong.

The MJO in 78 was similar to this year. Opposite signal, yet still a great winter after December.

[Quixotic1]

The MJO in 78 was similar to this year. Opposite signal, yet still a great winter after December.

78-79? I know HM has that as one of his pets. A lot of people had 76-77 and that has been a pure D fail.

[aggiegeog]

After studying the models on tomorrow's storm for a few minutes it looks like if we can get the precip to fall heavy enough we could see snow otherwise it will be just a light, cold rain with temps around 40.

[bubba hotep]

Big quick shot of cold air coming on the 23rd as the Plians storm wraps up into a powerful cyclone .ear the Great Lakes into Canada. Convection near Hawaii builds a big Western Ridge that eventually ridges into Alaska as the Canadian cyclone retogrades to near Hudson Bay. The operational and Global ensembles suggest a big 1050 to 1060mb Arctic High drops across the N Pole from Siberia and pushes S across the Canadian Praries and pushes into Montana and Wyoming near the 30th ushering in a very strong front arriving by New Year's Eve. There continues to be some indications that a Southern tracking storm arrives a day or two later with some potential of a Coastal low/wave developing along the Lower Texas Coast after the cold air is entrenched across our Region.

This has my attention and a good number of the 00z Euro EPS members get significant snows into Texas.

[vwgrrc]

Was looking at wunderground D10, it shows a bit icy on 12/31 morning here in DFW. But the temperature seems too high for any accumulation...  No sure how accurate are they in type of weather!

[Srain]

Afternoon briefing from Jeff:

 

Strong cold front will sweep across the area Tuesday.

 

Potent upper level storm system will move across the plains and into the OH valley early to mid this week allowing a cold air mass to move southward across TX starting Tuesday. Low level warm advection is in progress today with southerly winds pumping moisture back into the region. Main dynamics with this storm system will be northeast of SE TX, so not expecting much in the way of rainfall or severe weather compared to locations just to our east on Tuesday. Could see a line of showers with the front. Main news will be the strong post frontal winds of 20-30mph on Tuesday as cold air moves into the region from the north. Temperatures Tuesday morning in the lower 60’s will fall into the 40’s by late afternoon under strong cold air advection.

 

Will go ahead and lower both highs and lows for both Christmas Eve and Christmas Day as upstream air mass is slightly colder than projected yesterday. Some locations could be close to freezing Christmas morning and while southerly winds will return during the day, the warm up will be tempered by the cold start so instead of near 70 probably lower 60’s for highs. Skies will be sunny both Christmas Eve and Christmas Day.

 

Long Range:

Problems and a lot of them in the extended as models continue to attempt to grasp a potential arctic air intrusion into the US in the days before New Year’s. There has actually been very little change in the upper air pattern features of a ridge building into Alaska and a large and deep downstream trough carving out over much of the US. The upper air pattern would suggest arctic air is delivered into the US via Montana and North Dakota around the 28-29^th and then pours southward down the spine of the Rockies and into TX by the 31^st. Surface pressures on the order of 1050mb or greater over Montana toward the end of December is certainly noteworthy.

 

While the source region of NW Canada is not exceptionally cold at the moment the setup in the flow aloft would appear to bring the currently bitter cold northern Russian air mass into NW Canada by early to mid next week and then deliver it southward into the US during the mid to late part of next week.

 

Of other interest continues to be the threat for a fairly strong storm system to move across TX with a potentially cold arctic air mass in place. This raises all kinds of P-type concerns from the 31^st into the 2^nd across much of the state including SE TX. The amount of cold air that moves southward will likely determine the overall outcome with respect to P-type during this period along with any potential for accumulations. Needless to say… the mid to late week period next week will be the main forecast focus over the next several days.     

 

[aggiegeog]

Was looking at wunderground D10, it shows a bit icy on 12/31 morning here in DFW. But the temperature seems too high for any accumulation...  No sure how accurate are they in type of weather!

I would not be too concerned with temps being too warm for next week as highs will be hard pressed to reach freezing by that point as alluded to in Srain's post by Jeff. The upper air is set up to deliver very cold temps straight from Siberia and the Pacific should do its part by sending a train of systems our way.

[vwgrrc]

I would not be too concerned with temps being too warm for next week as highs will be hard pressed to reach freezing by that point as alluded to in Srain's post by Jeff. The upper air is set up to deliver very cold temps straight from Siberia and the Pacific should do its part by sending a train of systems our way.

Great. Sounds like we should have enough cold air, hope the precipitation lasts into the first week of Jan.

[aggiegeog]

Great. Sounds like we should have enough cold air, hope the precipitation lasts into the first week of Jan.

We will see how the pattern develops. Right now the models are losing the AK upper ridge by then, but I could see it holding on longer.

[vwgrrc]

We will see how the pattern develops. Right now the models are losing the AK upper ridge by then, but I could see it holding on longer.

Actually, people in SE subforum are now getting very pessimistic about the overdue pattern change  Not sure if Texas get different treat... 

[aggiegeog]

Actually, people in SE subforum are now getting very pessimistic about the overdue pattern change  Not sure if Texas get different treat... 

The GFS gives me no reason to doubt the coming weather. The Euro just has a progressive AK ridge and a slow to eject SW low. Maybe I am just optimistic, but the GFS pattern looks more likely. Now for the SE I could see how the SE ridge may shunt the cold away.

[stumpy]

Some of those SE folks live to much on the cliff ready to jump at a single bad model run........