December-Wet/Stormy New Years Eve Ahead

[srainhoutx]

There still remains a lot of uncertainty, but the cold sector N and W of the I-20 Corridor appear to a chance of seeing some light snow with most if not all the ABQ Region into Amarillo and lighter amounts S into Lubbock, northern areas of San Angelo and on E into the Dallas/Ft Worth area. Warning criteria may be met for ABQ with snow to the Rio Grande Valley floor in that New Mexico Region and potential Advisory criteria further E into FWD. The forecast confidence remain low, so expect changes.

Further S in the warm sector a strong line of showers/storms may be likely overnight Sunday into early Monday. There still remains a lot of uncertainty with timing of the Canadian front, so stay tuned as the model mayhem continues.

[srainhoutx]

Morning e-mail from Jeff:

Strong Canadian cold front will sweep across the region Sunday night ending this warm and muggy weather. Highs on Monday will struggle to reach 50 under strong cold air advection and cloud cover.

However before Sunday evening we must continue with this warm and humid air mass and the daily cycle of morning low clouds and fog followed by afternoon partly cloudy skies. Lows in the 60’s and high near 80/low 80’s may approach record values over the weekend. Moisture return off the Gulf will continue with the potential for a few scattered showers Saturday and Sunday. Amplification of the western US ridging sends a cold Canadian air mass down the plains and into TX Sunday. Will likely see a thin line of showers/thunderstorms along the front Sunday night, but once again the coverage looks meager with areas east of I-45 favored for the most activity. Maybe a few locations will squeeze out .50 of an inch.

While models have been slowing down the frontal timing, such cold air mass tend to plow southward faster than models suggest and expect the front to be off the coast by early Monday morning. The temperature will fall a good 10-15 degrees with the front and then continue a steady decline on Monday under strong cold air advection. Upper level trough remains west of the area into Monday and Monday night and this should keep clouds in place over top of the deepening frontal inversion. The combined effects of clouds and strong cold air advection will result in a cold Monday with highs in the 40’s to low 50’s with gusty NW winds of 10-25mph.

Skies might clear out early enough Monday night/Tuesday morning for near freezing conditions over parts of the area. Still expect winds to stay up some with the ridge axis just to our west, so conditions are not completely perfect for strong cooling. Better setup may come Tuesday night/Wednesday morning with ridge axis nearly overhead and mainly clear skies. Could see temperatures near or below freezing all the way to I-10 and in the rural areas away from Houston. May need a freeze warning for this time period…but much can change over the next few days especially with cloud cover.

After Tuesday, the models diverge on the prospect of the next trough affecting the area. A few models develop a coastal storm off the lower TX coast and keep the cold air locked in place with overrunning rains while other bring the warm sector inland and are much drier. I am tending to lean toward the drier solutions given the ongoing pattern this fall and the worsening drought conditions.

Fire Weather:
Some concern on Monday for fire weather conditions, but current expected cloud cover and higher RH should help mitigate strong gusty winds. Additionally, some rainfall is likely on Sunday night which should help to wet the finer fuels. Will keep an eye on this aspect over the weekend, in case RH values fall more than expected.

[Portastorm]

Not that I'm a big fan of the NAM ... but it is interesting to note that the 6z NAM run continued showing a little bit of light snow or ice pellets from areas Texarakana into the Hill Country on Monday morning.

[srainhoutx]

Not that I'm a big fan of the NAM ... but it is interesting to note that the 6z NAM run continued showing a little bit of light snow or ice pellets from areas Texarakana into the Hill Country on Monday morning.

It's not just the NAM. The SREF long range is sniffing a similar scenario. We are still a long way out and things will likely change. I'm just not sure if the column will be saturated enough to support anything reaching the ground.

[srainhoutx]

I'm a bit more interested in the third in a series of short waves that has been suggested for several day now via the operational guidance. This feature has the potential to drop snow across Arizona and New Mexico with a Coastal low developing along the S Texas Coast providing for increased moisture and slightly better dynamics in the cold sector. It does appear we are in an active/stormy pattern with multiple opportunities for Winter Storm threats.

[cristina99]

Now this is what I am talking about! Come on winter!! Maybe a cold Christmas - with a hint of sleet. Maybe?

[Belmer]

Are you referring to the CFSV2 model?

[Belmer]

The 06z NAM is looking a little bit more exciting again tonight for those in Central TX:

Hour 78




Hour 81




The 12z NAM still holds out hope of some ice/sleet pellets or two, but not as exciting as it was last night:

Hour 72




Hour 75


And last but not least, for the ones starting to look at Christmas time...

CFSV2 model

[Belmer]

It seems that I need a tutorial lesson on how to make images smaller.
Sorry everyone!

[Andrew]

It will be nice to see some cooler weather but the longer range colder weather or any type of wintry precip looks dull. Looking at the global models over the last couple of weeks a more and more progressive outlook has taken shape. GFS and Euro are no longer as defined in the intensity of the trough at 500mb and both models leave some energy behind before it all transitions east during the middle of the week. The 250mb forecast shows the ridge in the Northeastern pacific breaking down
and sinking south allowing a 150+kt jet to sink straight south. Unfortunately the intensity of the jet looses form as it reaches the central plains. Taking a look at the 500mb hgt and vorticity both global models want to leave energy behind after the initial trough makes its way through allowing for a short wave to approach through the middle to end of the week. We then continue this pattern as more energy makes its way down from Western Canada/ the pacific towards the rockies. While the next shortwave/ disturbance next weekend doesn't look as strong there could be energy from the pacific that could help to amplify it as it coasts across the central U.S. The problem I see is that any cold air that does make its way south is going to move east rather quickly. The pattern looks progressive and doesn't look to change anytime soon. By the end of next week surface winds should return from the south as moisture filters back into the area pushing our temps back to what they were before. Luckily both the NAO and AO look to go into a negative phase (stay in a negative phase) which is helping this air to drop south but until things slow down the "stepping down" process that we really need for really cold air down here won't happen. At least with the jet slipping farther south (and possibly staying there for a little) we could see a higher chance of rain down here which we really need with the drought. Hopefully late December/January can bring some real change and fast.

[Andrew]

Also to add to model inconsistency the Euro switched to a positive NAO phase in the near future which is directly opposite of what was suggested in the 12z run. The ridging in the Northern Atlantic isn't as prominent and the operational 500mb heights show the more progressive movement overall. While things do look more promising than earlier in the season I think later in the year will be when things get real interesting.

[wxman57]

Latest GFS run isn't much different. Cold front moves through late Sunday night/early Monday morning. Rain ends soon after frontal passage with the temperature in the 50s-60s. Low in the mid to upper 40s Monday with a high into the low-mid 50s (though the recorded high will be at 12:01am - mid 60s). A couple days with lows in the mid 30s and highs in the 50s followed by a warm-up. No winter weather here. Closest may be in the panhandle.

[redneckweather]

So much for a pattern change everyone has been barking about the last few days. Just a run of mill good cold front...normal for this time of year...and then a warm up. Is this about right?

[Portastorm]

So much for a pattern change everyone has been barking about the last few days. Just a run of mill good cold front...normal for this time of year...and then a warm up. Is this about right?

I would call knocking daily high/low temps down 15-20 degrees for several days a "pattern change." Otherwise, you'd have 70s and 80s this next week with no change in sight. I don't think anyone around here was talking about "The Day After Tomorrow" happening in SE Texas or anything.

[srainhoutx]

Yep. It is a pattern change. How quickly some for get that we have seen little to no rain since October with a never ending Gulf of Alaska Low vortex and a purely zonal dry flow from W to E throughout the entire months of October/November (about a 6/7 week period). That pattern is now being replaced by one that brings a general troughiness/storminess into the Intermountain West/Plains and keeps all the warmer air shoved off to the E. I know I have mentioned we are entering a roller coaster pattern where fronts will become a bit more active and bring moisture and warm up, only to cool off with the next storm system.

[redneckweather]

Portastorm, I think you know what I meant by 'pattern change'. I'm not talking about a good cold front that sticks around for a few days. I'm talking about people who were saying this front is the beginning of the long awaited pattern change...a stepping down process. As of this morning, that does not look to be the case...just a good solid front followed by a gradual warm up with no REAL cold air anywhere in the extended coming south. If you are seeing things differently, let me know.

[redneckweather]

srain, here is a quote from Andrew. Agree or disagree? I'm just trying to figure things out here.


The problem I see is that any cold air that does make its way south is going to move east rather quickly. The pattern looks progressive and doesn't look to change anytime soon.

[srainhoutx]

srain, here is a quote from Andrew. Agree or disagree? I'm just trying to figure things out here.


The problem I see is that any cold air that does make its way south is going to move east rather quickly. The pattern looks progressive and doesn't look to change anytime soon.

I agree. That is why I said 'roller coaster', redneckweather. That is a laymen term for a progressive pattern. One of the things that we have not had is a progressive pattern. It has been purely zonal. No split flow...nada. Nothing but zonal. That is changing as we speak. What is lacking for a wholesale pattern change for us here in the Central United States is a bit of a +PNA. That is a ridge of High Pressure right along the Coastal California/Pacific NW Regions that noses up into Alaska. The current Ridge in near the Aleutian Islands nosing up into Siberia. In simple laymen terms there are already hints that the MJO or tropical forcing will increase and build the +PNA near Christmas. We need a N to S Arctic/Polar jet to scream S along the leeside of the Rockies to deliver the very chilly air that has built up in our source regions of NW Canada. Last year there was no snow pack above average temps and absolutely no chance of winter at all down here other than Midland that set records with snow events due to cold core closed upper lows that happen to track across far W Texas. If we look back in history…and I'm certainly not suggesting that the pattern currently favors this, some of our bigger Arctic type events of years gone by saw major warmth followed by a big dump of Arctic air into the Plains. A SE Ridge is already showing up suggesting our neighbors along the East Coast have a lot to be concerned about for winter weather this year. We in the Central part of the country may be the only folks that actually get a winter pattern at all. I listened to a long range webinar by our friends at Impact Weather a week or two ago and their long range forecaster suggested about a 30% (doesn’t sound like a lot but in long range forecasting it is a rather strong statement) chance of a hard freeze along the Western Gulf Coast into Louisiana and several ice threats late December into early February. Take it for what it's worth, but I'm just happy for those folks in New Mexico today that are under a Winter Storm Watch today. They have been in a drought now for almost two years and the pattern suggests more opportunities with this progressive stormy pattern developing for the next several weeks.



From NWS Brownsville: (note highs near 90 falling to the 50's/low 60's to 40's in the Rio Grande Valley)...a 30-40 degree temp drop...I'd say that is sharply colder as well...

The odds of seeing showers and thunderstorms will increase Sunday, along and ahead of a strong cold front that will sweep across the Rio Grande Valley and Deep South Texas Monday. Gusty north winds in wake of the front, occasionally reaching speeds around 30 MPH, will usher in a colder and drier airmass into the region by Monday night. Small Craft Advisories will likely be required over the marine area, and there's the possibility of gusts reaching gale force as well. Temperatures Monday are expected to gradually rise into the 50s and 60s over the region, with the northern brush country likely not making it out of the 50s. Mostly clear skies Monday night will allow temperatures to quickly fall after sunset, bottoming out in the middle 30s (Brush Country) to middle 40s (coast) by daybreak Tuesday. These colder temperatures will likely continue through the middle of the week. -Vega/Billings-

[TexasBreeze]

Think positive.....

[Portastorm]

redneckweather, I don't think I could say it any better than srainhoutx.

But I do agree with you that this is not a "pattern" where we would gradually step down into winter darkness. Progressive is the keyword, for now.