December-Wet/Stormy New Years Eve Ahead

[srainhoutx]

Just a bit of a potential Holiday teaser for those wondering what the longer range guidance is sniffing. As stated early, there have been some indications that things could become a bit interesting near the Christmas time frame and we are now seeing some consistency in the guidance solutions. The GFS is suggesting tropical forcing will change that pattern that has plagued the N Pacific to a more favorable pattern to deliver all that cold air that has been building across Alaska and Western Canada S into the Lower 48. The GFS operational as well as the ensembles have been slowly but steadily trending toward developing large dome of High Pressure over Alaska as well as another dome over or near Hudson Bay. As we have been discussing a progressive pattern has developed and the Sub Tropical Jet is becoming active or noisy with disturbances riding NE from the Central/E Pacific Ocean. At the same time trough after trough of low pressure sweeps down the W Coast and an occasional surface low develops as well as an upper low at the 500mb level. These series of low pressures will ride along the Polar jet that is slowly but surely dipping further S.

Now what does that mean for New Mexico, Texas, Oklahoma and Louisiana? Increased storminess in the progressive fast moving flow will begin to slow as blocking well to our N forces an active Southern Stream storm track. In time as we near the Christmas Holidays, the Polar Jet and the Sub Tropical Jet will be in close proximity to each other. Cold air will build across the Western US first and the slowly progress eastward in about a week to ten days. What we'll need to monitor is the potential for a building snow pack across the Plains and the Rockies during the next week or two. There is multiple storm systems already on the horizon to our NW and that should continue for the foreseeable future. For the cold weather lover, things do appear to be heading toward a pattern that would favor unloading some of that very cold air bringing it S into our Region near Christmas. There still remains a lot of uncertainty, so expect changes in the days ahead.

[srainhoutx]

Yep. The GFS 72 hour precip totals are increasing. Fingers crossed.

[weatherguy425]

Besides a cold Christmas time period, the GFS has also at-least 'thrown around' the idea of a very cold period beginning around the 28th (+/- a day or two) with significant storms continuing to traverse the southern tier of the nation.

[Portastorm]

Just saw that 12z GFS run ... oh my!!

Another Christmas Snow Miracle in the works?!

[MontgomeryCoWx]

Yeah, I saw that and peed my pants a little.

[srainhoutx]

For our neighbors in far SE TX and Southern Louisiana...Hard Freeze and Freeze Warnings are in affect tonight...

[jasons2k]

For our neighbors in far SE TX and Southern Louisiana...Hard Freeze and Freeze Warnings are in affect tonight...

Yeah, no kidding! I read Jeff's email this morning, so the first thing I did when I got home was to remove all my freeze covers. Then I came inside to read the NWS discussion and they mention another front moving through, and my forecast low is 29! Mmmm-Kay. So I just had to turn right around and put the covers back out....

[jasons2k]

^^ Less than 2 weeks until the 8th anniversary of the Christmas Snow Miracle.

Yep, and 8 years and counting that 'this is the year we're gonna see a repeat - because the GFS says so!'

[Ptarmigan]

^^ Less than 2 weeks until the 8th anniversary of the Christmas Snow Miracle.

Yep, and 8 years and counting that 'this is the year we're gonna see a repeat - because the GFS says so!'

Let's hope for Christmas snow,

[srainhoutx]

Another very chilly morning across the region with a freezing 29 degrees here in NW Harris County. Temps should begin to moderate today as an easterly flow begins and finally a warm front pushes inland tomorrow night setting the stage for a very damp weekend. Best rain chances appear to be later Saturday into Sunday as the trough ejects NE from the Great Basin and a Pacific front finally clears the Coast during Monday.

Looking ahead to later next week, the longer range guidance continue to advertise a very cold air mas moving S from Canada as a 1055mb+ Arctic High slides into the Plains and a noisy sub tropical jet continues. There are increasing indications that the MJO will move into octant 1 suggesting a very cold period may be lurking as we near the Christmas Holidays. Stay Tuned!

[wxman57]

OT- is the freezing point of water exactly 32.000000000 ºF? And why I am now thinking of p-chem classes and freezing point depression and why a good margarita will have frost, not dew, on the outside of the glass...

I have seen water that is still water despite being at or below 32ºF. The water in that case was pure with not dust or contaminant. The same kind of super cooled water that help bring down Air France Flight 447 over the South Atlantic on June 1, 2009 after the super cooled water came in contact with pitot tubes.

The absolute temperature for water to freeze is -55ºF or -48ºC. 32ºF occurs if the water has contaminants like dust and under normal atmospheric pressure on the surface.

Water's Ultimate Freezing Point
http://news.discovery.com/earth/coldest ... 11123.html

32F is more properly identified as the melting point of pure ice, not the freezing point of water. Any impurities added to water will cause its freezing point to be lowered (molar freezing point depression). Pressure also affects the freezing point of water. Your margarita had frost on the glass because the impurities in the margarita (salt/alcohol) lowered its freezing point, which allowed the drink's temperature to drop below 32F (like when you make ice cream).

[Portastorm]

I've noticed that the CFS v2 weekly forecasts for the last week in December and first week of January have cooled considerably in the last few days.

http://www.cpc.ncep.noaa.gov/products/p ... /cfs_fcst/

[unome]

it' reached 5 degrees colder than when I peeked at our forecast last night

forecast was 32, 6 hr min was 27 at Hooks http://w1.weather.gov/data/obhistory/KDWH.html

it made for frosty star gazing, but I saw a beautiful one just below the big dipper about 5:30 - not sure if it was Geminids or from Comet 46P/Wirtanen

[unome]

I'm not much into the Mayan calendar hype, this is where I leaned of the comet

http://earthsky.org/space/new-meteor-sh ... 2-geminids

more on 46P http://cometography.com/pcomets/046p.html

edit to add interactive sky chart (requires registration): http://skychart.skyandtelescope.com/skychart.php

[srainhoutx]

The 12Z GFS is a bit more bullish on our rain chances for Sunday.

[srainhoutx]

The long range la la land GFS continues to advertise another cold snap right before Christmas. We will see.

[MontgomeryCoWx]

Looks good!

[srainhoutx]

The 12Z Euro is a tad slower with the trough to our W and offers a bit more rain chances than the GFS this weekend. Looking further out via the Euro...oh my...Arctic Air mass (near 1050mb High Pressure) spilling S into the Plains near the Christmas Holidays...

[MontgomeryCoWx]

Looks like a potential noreaster near the Holidays there....

[srainhoutx]

Could be. I think the general idea that the very long range GFS and its ensembles starting 'sniffing' several days ago could very well be possible near Christmas. The Euro is trending toward a West Based -NAO/tanking AO and the EPO going negative and popping a +PNA. That is the recipe required to dislodge the cold that has been bottled up in Alaska/Western Canada the past couple of months. For the cold weather lovers, those are somewhat encouraging signs to see. A lot can change, but with the Holidays approaching we'll continue to monitor.