January Weather Discussion: Slight Chance Severe Storms

[Paul]

06z GFS not as cold the last night 0z but looking at beyond 300hr and your see something we dont typically see down here...wow

[srainhoutx]

Before things get to crazy, I'd encourage folks to start thinking about some preparations if all this comes to fruition. The more we pre plan for an event like this the better we will be prepared if it does occur. I'll likely start a pinned thread concerning things one can do to protect property and such in a day or two as we continue to monitor this threat and begin to fine tune what will be the sensible weather for our area. I do encourage folks to stay tuned and follow this potential event closely in the days ahead.

[srainhoutx]

Here are some notable La Nina Winters of the past and could shed some light on what may be ahead as well as what has happened in the past regarding these type events via NWS Austin/San Antonio...

The averages do not pick up the extremes that have occurred since the Fall of 1949 and Winter of 1950. For South Central Texas, although on average moderate to strong La Nina conditions favor increasing probabilities of warmer and drier periods from the Fall through the Winter, there have been a few exceptions in the sub tropical climate over South Central Texas. Even though the active wintertime jet stream is displaced north of South Central Texas, there have been cases since the Fall of 1949 and Winter of 1950 where sub tropical weather patterns linked with features over the Tropics and Mid Latitudes to bring occasional cold outbreaks and periods of heavy rain and precipitation to South Central Texas. A few significant Arctic Outbreaks have come during La Nina Events, including December 1950; late January to February 1951; January and February 1985; February 1989; and January and February of 1996. Another feature that shows up with La Nina winters is more extremes between warm and cold, especially with the dry winters. February of 1996 was an extreme example where it was very cold at the beginning of the month, then set all time February Highs on February 21st, followed by very cold conditions at the end of February 1996. The February monthly record high at Del Rio of 99 on February 21, 1996 was later tied, when the high was 99 on February 25, 2008. The high on February 21, 1996 at Austin Mueller Airport was 99, at Austin Bergstrom 101, and at San Antonio 100 on February 21, 1996. The Winter of 1964/1965 had rainfall wetter than usual for Austin and San Antonio. The winter of 1967/1968 was wetter than usual at Austin, Del Rio, and San Antonio. In January 1968, a slow moving cutoff low came across the area from the west and caused a January flood, similar to the December 1991 floods. The January 1968 case occurred during a weak La Nina period, while the December of 1991 case occurred during a moderate to strong El Nino. January 1968 was the wettest January at San Antonio and the 4th wettest January at Austin Mabry. In November of 1974, during a La Nina period, a heavy rain event came to Austin, and caused flooding. From the Fall of 1984 through the Winter of 1985, during a La Nina period, wetter than usual conditions came most of the time, as relief from the dry period in 1984 came in the Fall of 1984. There were also a number of cold outbreaks in January and February of 1985. This included the heavy snow event that came in January 1985, a record for San Antonio and Del Rio and the 7th heaviest snow for Austin. In January 1985 the first snow event came January 2nd followed by a 2nd snow event from January 11th to 13th, 1985. January 1985 holds the record for the most snow in a month at San Antonio, 15.9 inches of snow, and at Del Rio, with 9.8 inches of snow. For snowfall at Austin January 1985 comes in 2nd place with 7.5 inches of snow, after the record of 9.7 inches of snow in January 1937. Floods from a heavy rain event in October 1998 during La Nina were followed by very dry conditions from December 1998 through the Winter of 1999. In the La Nina period from the Fall of 2000 through the Spring of 2001, wetter than usual conditions came, accompanied by occasional cold outbreaks.

http://www.srh.noaa.gov/images/ewx/wxev ... ntrltx.pdf

[srainhoutx]

The 12Z GFS continues the trend and depicts a 1062 mb Arctic High in Western Canada...

[srainhoutx]

The 12Z GFS also suggests a storm taking shape to our SW/W in the 240 hour time frame. With all the cold air in place via the GFS at that time, wintry weather breaks out and spreads across the Lone Star State.


Edit to add:
From my buddy Jorge (wxmx) from Americanwx...

Also, the configuration of the 500mb pattern is also exceptional, since there's more support for the West coast ridging "phasing" (connecting) with the EPO ridge...although not shown yet by the models, that could bring the holy grail of polar/STJ longwave phasing well south. Still, it shows a pattern that's good for overrunning for far S and SE TX. Also of note, is that the models are faster with the dense airmass coming south (Dec 11th) vs previous run, and they are agreeing in that it would be at least a 2 step cold shot, which means a long duration event.

[harpman]

Srain, I know this is a south Texas forum, but many times what you guys get in the Houston are eventually effects us here in the New Orleans area. This pending cold shot/precip event, will this have an equal effect of those of us in south Louisiana?

[srainhoutx]

Srain, I know this is a south Texas forum, but many times what you guys get in the Houston are eventually effects us here in the New Orleans area. This pending cold shot/precip event, will this have an equal effect of those of us in south Louisiana?

It does harpman, IF the models and other medium and longer range signals are correct. And for the record, we have folks that are members and folks that follow us far beyond the local SE TX area.

[harpman]

Thanks, I've been following this forum for a while. I belong to a wx forum here in the New Orleans area, but it's always wise to see what others along the gulf coast are thinking as well.

[srainhoutx]

12Z GFS in fantasy rain, weekend from next, a small sleet storm....

01032011 12Z GFS_3_2011010312_F264_SNOWIN_SURFACE.png

01032011 12Z GFS_3_2011010312_F276_SNOWIN_SURFACE.png

01032011 12Z GFS_3_2011010312_F288_SNOWIN_SURFACE.png

01032011 12Z GFS_3_2011010312_F300_SNOWIN_SURFACE.png

01032011 12Z GFS_3_2011010312_F324_SNOWIN_SURFACE.png

[brazoria121]

hi guys! first time poster LONG time reader with all this talk of the cold blast i was just wondering im in angleton close by the coast and i was wondering IF all this is correct since its so far out would it get below freezing here for some wintry precp?

[Paul]

theres that low developing to the west on those maps....likely track east.......that is some serious cold run on the 12z...though some of that is in the 288hr frame and beyond.....I am on board...time for wxmn57 to climb on the Polar Express....

sorry cuoldnt resist...I have watched that movie at least 20 times over the holidays thanks to my 3yr old daughter...

[srainhoutx]

hi guys! first time poster LONG time reader with all this talk of the cold blast i was just wondering im in angleton close by the coast and i was wondering IF all this is correct since its so far out would it get below freezing here for some wintry precp?

First off, welcome and we're glad you've decided to join in the discussions. We'll need to see how things unfold in the days ahead before any real forecast can be issued regarding how cold and where this event sets up. Stay tuned and don't be afraid to chime in as well.

[sleetstorm]

Srainhoutx, of all those computer models depicting snow depth in inches, are the last three showing what appears to be another wave of low pressure in NE Mexico making its way ENE or NE?

[Mr. T]

Looks like a long duration icing event from day 10 onward on the 12z GFS, if we really wanted to get technical, but the exact details are not important

Just another run showing an arctic dump across the Lower 48

[srainhoutx]

Remember are talking about something very far out in model world via the GFS, sleet. But yes, if one follows the charts as well as the twister site data, there does appear to be another weaker wave following the 240 storm that spreads light wintry precip across virtually all the Lone Star State heading E. Again, we will see how this eventually plays out before getting too excited regarding any moisture. The bigger item of concern is the Arctic Air mass and any potential reinforcing shot of very cold air.

[biggerbyte]

Like srain said, it is too early to talk about specifics. Let's give it until Wednesday or Thursday. The models are being pretty persistant that something big is cooking. One does not even need that to see that at some point changes are coming. However, let us not forget that we are some days away from this event. We should be able to decide the if, when, and where by the end of this week. It sure is exciting to see this much potential. One surely can not deny that we don't see this much eye candy in the models without something big happening for someone in the States. Hopefully that "someone" are all of us here in S.E. Texas.

AZ... Whip out Dan's magic ray gun... Bring on the cold, then bring on the moisture..

[srainhoutx]

The 12Z Euro is suggesting a 1065 mb Arctic High in the NW Territories Of Canada heading S @ 174 hours.

[TexasMetBlake]

How do you get 174? I'm looking at the Euro and the upper-level pattern, per the 12z, is the upper flow is very zonal. The ridging is not THAT impressive. However it could continue to amplify and spill south. I'm watching for the McFarland (sp) Signature which is basically an omega block over Alaska to allow this air to move straight south and what I am seeing is not classic.

[srainhoutx]

How do you get 174? I'm looking at the Euro and the upper-level pattern, per the 12z, is the upper flow is very zonal. The ridging is not THAT impressive. However it could continue to amplify and spill south. I'm watching for the McFarland (sp) Signature which is basically an omega block over Alaska to allow this air to move straight south and what I am seeing is not classic.

PPV.

[Mr. T]

The 12z euro is colder and faster with the first arctic front in a week, and it has also jumped on the gfs bandwagon with much higher pressures across western Canada

Much better than the 0z run if you like cold