2008-09 Texas Winter Weather Thread

[cctxhurricanewatcher]

Here is the latest from Jeff Lindner:

Temperatures warming very slowly under overcast deck and cold air advection.

All area temps. remain in the 40’s as of 1000am with a 39 still at Crockett. Cloud mass moving SW across the area…however even upstream temps. under sunny skies still in the mid 30’s around Dallas with nosing 850mb ridging resulting in continued cold air advection.

Looking for some fairly cold lows tonight if skies can clear out. Given dewpoints falling into the mid 20’s northern areas now which should filter south supports near freezing temps. in many areas. Saving factor may be the center of the high stays to our north allowing winds to stay up and temps. from bottoming out. Friday night we may not be as lucky…however S TX coastal troughing becomes established and clear skies may cloud over during the afternoon and evening saving parts of the area from a freeze. Tough call so for now will go with near freezing tonight along and N of US 59 and in the typical cold areas such as Angleton. Freeze may be more widespread Saturday morning…will have to see how things line up on Friday.

Will need to continue to maintain close watch on far range extended as models continue to show potential for significant arctic air intrusion into the US around the middle of the month. Additional factors appear to be coming into play to add more confidence that a significant…possibly…record breaking cold air event could be in the making. Model signals are showing similarities to historical cold air events in Dec 1989 and Dec 1983…close watch on this is needed.

FWIW I've seen many mets, including Jeff, mention '89 and '83 many many many times over the years and we haven't seen anything close since...well...1989.

That's true. But we do see a consensus developing this time around that something big MIGHT happen.

It's bound to happen someday. The Texas coast hadn't seen Hurricane activity we saw this last year (save 2005) for several years when every observer of Texas weather had been amazed we went that long without some major hits. Same thing with Arctic attacks of significant impact. Looking back at the one's that impacted the RGV for example, it seems they come in 10 to 15 year increments with rare execeptions in the 80's. So, yes someday the Big Dog is going to come down for visit. Is it this year? We'll soon find out.

[wxman57]

12Z EC is slower and wetter with next Tue/Wed's event. It also shows cross-Polar flow developing in the 8-10 day range.

[Big O]

12Z EC is slower and wetter with next Tue/Wed's event. It also shows cross-Polar flow developing in the 8-10 day range.

I just sent you a PM. Some have analogized the Day 10 12z Euro pattern with a 1062 mb HP over Montana to the pattern on 12/24/83. If memory serves right, that was one of the coldest days on record in Texas. If the 12z Euro Day 10 forecast verfiied, what would be looking at in terms of temps and wintry precipitation in Texas?

[Portastorm]

12Z EC is slower and wetter with next Tue/Wed's event. It also shows cross-Polar flow developing in the 8-10 day range.

Cross-polar flow??!! SO-WEEET!

[Ed Mahmoud]

Hmmm, an East-West oriented trough near the Canadian border, with Northerly flow North of it, and zonal flow below. I was just re-reading the McFarland paper yesterday...

As shown in Figure 4, the 500 mb patterns during the 1951 and 1962 Arctic outbreaks were very similar; a deep polar vortex over Baffin Bay, a major trough over the northern United States with an east-west trough line, zonal flow south of the trough line and northerly flow from a high amplitude ridge north of the trough line. The events preceding these patterns were also very similar.

From the breakdown of a high-latitude short wave omega-type block in the long wave ridge, the trough associated with the eastern low moved southward, intensifying while maintaining a general east-west orientation. The combination of the ridge aloft and surface radiative cooling facilitated the development and maintenance of the surface anticyclone, which also began to move southward under the northerly flow aloft. In the four days from 5 Jan to 9 Jan 1962, the surface anticyclone built from a 1025 mb central pressure over the Bering Straits to a 1060 mb high over Alberta.

In both cases, the omega block opened up as the leading trough line moved southward. The closed high circulation of the block became joined with the full latitude long wave ridge over the western coast and the southward moving trough line became linked to the deep low over Baffin Bay.

Another key feature was the cyclogenesis associated with the developing system. In each case, pronounced cyclogenesis occurred as the low occupying the mean long wave trough position over the U.S. was ejected. In January 1962, the surface low deepened from 1006 mb central pressure to 980 mb in a 24-hour period with the cyclogenesis.

Cyclogenesis did not occur with the southward moving trough. A consequence of a lack of cyclogenesis was that the cold air was not deflected eastward from its southward trajectory (Means, 1948). The history of the 500 mb and surface patterns from the first appearance of the block for the 1962 outbreak is presented in Figure 5 and the 500 mb sequence for the 1951 outbreak is presented in Figure 6.

[cctxhurricanewatcher]

12Z EC is slower and wetter with next Tue/Wed's event. It also shows cross-Polar flow developing in the 8-10 day range.

Cross-polar flow??!! SO-WEEET!

Getting the kicking shoes out the closet?

[Ed Mahmoud]

I just looked at the Euro on the PSU e-Wall, to see thicknesses and 850 mb temps and 850 and 700 mb relative humidities, and I think the Panhandle may get a decent snow or ice event.

Always hard to tell when looking at 24 hour time incremements, and humidities instead of actual precip.


I don't know why the Europeans don't make more model data available for free on the internet. Their taxpayers are paying for it, just like ours pay for the GFS, and the Canadians pay for the CMC, and one can see plenty of detailed data free on the world wide interweb from those models.

[Portastorm]

12Z EC is slower and wetter with next Tue/Wed's event. It also shows cross-Polar flow developing in the 8-10 day range.

Cross-polar flow??!! SO-WEEET!

Getting the kicking shoes out the closet?

Not quite yet ... but I'm rummaging through the closet, looking for 'em!

[jasons2k]

That's true. But we do see a consensus developing this time around that something big MIGHT happen.

It's bound to happen someday. The Texas coast hadn't seen Hurricane activity we saw this last year (save 2005) for several years when every observer of Texas weather had been amazed we went that long without some major hits. Same thing with Arctic attacks of significant impact. Looking back at the one's that impacted the RGV for example, it seems they come in 10 to 15 year increments with rare execeptions in the 80's. So, yes someday the Big Dog is going to come down for visit. Is it this year? We'll soon find out.

Yes, this is true as well. It is bound to happen again someday. Maybe even this season.

But I've seen similar setups modelled before in the 8-14 day range, with cross polar flow and bitter cold dumped straight from Siberia with the polar vortex so far south you do a double-take to make sure you're really looking at the US and not Canada. IIRC, just last season there was a pretty strong consensus for a classic McFarland block and it never materialized.

I've seen/read JB mention 1899 at least once a winter season most years I have been reading him since 2001. He calls it "the ghost of 1899". So far, it is just a ghost as it hasn't appeared yet. I've seen him and other mets mention 1983/89 almost every year and the GFS with conditional snow well into the GOM every day of the week and twice on Sunday before.

I'm just saying I'll believe it when I see it. Until then, all I can say is "It's December...of course it's gonna get cold". Just probably not that cold.

[Ed Mahmoud]

A flake or two mixed in with the showers near HOU Wednesday morning?

[wxman57]

A flake or two mixed in with the showers near HOU Wednesday morning?


http://www.meteo.psu.edu/~gadomski/AVN_0z/f132.gif

Unlikely. The airmass won't be cold enough and the moisture will shut down. The 00Z European continues the trend of cross-Polar flow and some very cold air coming down around the 15-18th. GFS is lost, it can't handle the pattern.

[Ed Mahmoud]

A flake or two mixed in with the showers near HOU Wednesday morning?


http://www.meteo.psu.edu/~gadomski/AVN_0z/f132.gif

Unlikely. The airmass won't be cold enough and the moisture will shut down. The 00Z European continues the trend of cross-Polar flow and some very cold air coming down around the 15-18th. GFS is lost, it can't handle the pattern.

Wait, you can get Euro output past Day 10?

[Ed Mahmoud]

Double Post from EWG's thread because I am as excited as I was back in 1976 and we went to the Harkin's house further inland in Massapequa because of the evacuation order for Hurricane Belle, and I saw cable TV for the first time.


That and the two 1978 snowstorms when I still lived with the Yankees explains my magnificent obsession....


................................................

Bastardi thinks the Euro trough position is a bit too far West - can you imagine if it is a bit farther East and Mr. Bittercolds -50ºF Siberian temps have 500 mb flow helping a dense airmass that would want to head for the Gulf anyway pushing it along?

[Portastorm]

Here is the latest from Jeff Lindner:

Cold air continues to filter into the region this morning.



Cloud shield is expanding northward from the coast and now extends roughly from Liberty to The Woodlands to Columbus. Temps. remain near or below freezing at 800am at Huntsville with upper 30’s and lower 40’s elsewhere. Clouds will continue to increase and spread inland as isentropic surface is saturated in the 295K layer resulting from incoming weak short wave over New Mexico. Tough call on how long clouds will stick around today into tonight. Would expect clouds to limit heating greatly today and highs near 50 if not the upper 40’s look good considering IAH is only 40 at 900am with cold air advection still in progress and a thickening cloud deck. Dewpoints are bone dry in the mid 20’s and if skies clear out and with the ridge axis overhead tonight…freezing temps. would be possible at all location except the waterfront and urban heat centers. Will have to see how the cloud cover plays out, but if skies clear several areas may drop into the upper 20’s tonight.



Sunny skies return Saturday and Sunday as polar high moves slowly eastward. Weak return flow will begin Sunday and then greatly increase Monday ahead of potent storm system to affect Texas Monday-Wednesday of next week. Will see increasing clouds late Sunday and then cloudy skies Monday as surface warm front moves northward across the region. Models prog good southern stream short wave to cross along with the warm front…so some thunderstorms will be possible. Quick warm up Tuesday as area is warm sectored ahead of a strong cold front and upper level low late Tuesday and Wednesday. Could see a decent rainfall event over SE TX along with some severe weather Tuesday as cold front crosses the region. Upper trough lags the front and will push across Wed. Latest GFS and CMC has the center of the upper low passing nearly over top of SE TX with cooling temp. profile. Will maintain all liquid for Wednesday as surface temps. will be well above freezing and profiles are not supportive of frozen precip. reaching the ground.



Very Long range:



GFS has completely lost the arctic air event it has been forecasting since Monday around the middle of the month….what a surprise! This seems to be typical of this American model to only flip back toward its original ideas in the 7 day out time period….much like it did for the 2004 Christmas Eve snow event. The GFS also tends to suffer greatly with shallow arctic air masses and does not move them far enough southward due to its poor consideration of arctic airs ability to ooze southward under its own density. The ECMWF continues to show a very cold pattern for the US with a massive high centered deep over Alaska ridging into the arctic circle and northern Siberia carving out a deep trough across much of the US. While there is little cold air in AK now…cold is building in northern Russia and Siberia and this type of upper level pattern would support a dislodging of a Siberian surface high and then large push of very cold air southward from Siberia across the pole through Canada and into the US…almost a straight shot dump across the North pole down the Rockies to the Gulf of Mexico. Many factors are at play: 1) how cold is the air mass in Siberia when the upper air pattern is favorable 2) How amplified is the upper air pattern and where is the location of the N Pacific ridge 3) Is this a one shot dump or multiple shots 4) Is there an undercutting sub-tropical jet to add moisture over the top of the shallow arctic dome…if so how deep is the cold air mass and how much moisture and what P-type. Since I cannot answer really any of this with any certainty…will just continue with the bears watching around the middle of the month.

[Ed Mahmoud]

OK, we all laugh at the CMC during hurricane season, but Canada never gets tropical cyclones. Well, almost never. They usually get storms well underway in the process to post-tropical transition. So maybe the physicists, mathemeticians, meteorologists and computer experts who write the code didn't spend much time on keeping every thunderstorm from feeding back into a Cat 5 over tropical waters.


But what do they have in Canada in abundance? Cold weather, snow, and ice! Remember the big Quebec ice storm a few years back?


OK, now we're talking very small amounts of precip around DFW, under a tenth probably, but based on the position of the 850 mb freezing line and the 540 dm thickness line, I think the cold air may come in shallow, and you don't need much freezing drizzle on a weekday morning to cause great excitement on the bridges and overpasses of the 635 Loop

[jinftl]

Don't tell the folks in Nova Scotia that they never get hurricanes! (i.e., Hurricane Juan...made landfall as Cat 2)

OK, we all laugh at the CMC during hurricane season, but Canada never gets tropical cyclones. Well, almost never. They usually get storms well underway in the process to post-tropical transition. So maybe the physicists, mathemeticians, meteorologists and computer experts who write the code didn't spend much time on keeping every thunderstorm from feeding back into a Cat 5 over tropical waters.


But what do they have in Canada in abundance? Cold weather, snow, and ice! Remember the big Quebec ice storm a few years back?


OK, now we're talking very small amounts of precip around DFW, under a tenth probably, but based on the position of the 850 mb freezing line and the 540 dm thickness line, I think the cold air may come in shallow, and you don't need much freezing drizzle on a weekday morning to cause great excitement on the bridges and overpasses of the 635 Loop

[Ed Mahmoud]

I'd argue that extra-tropical (Canadian speak: post-tropical) transition was well underway at landfall, just judging from the satellite. Not saying it wasn't still a TC, just that it had started the process. But Juan is as a borderline Cat1/Cat 2 is an exception.




Anyway, just trying to keep hope alive for a no school day in the HEB ISD next week...

[Ed Mahmoud]

HAPPY HAPPY JOY JOY! HAPPY HAPPY JOY JOY!


New 12Z GFS shows a significant ice changing to snow storm for Houston only 15 days away!!!!




I'm not 100% committed yet...

[jinftl]

Would any wintry precip...even a coating....result in delayed school openings or closures in houston? People in the north would scoff at that....but it is all relative. When temps got below 40 (widespread...even beaches) a few years back here in south florida (with clear skies), school openings were delayed till noon or so. Now that would give a chuckle to folks from 'anywhere else'!

I'd argue that extra-tropical (Canadian speak: post-tropical) transition was well underway at landfall, just judging from the satellite. Not saying it wasn't still a TC, just that it had started the process. But Juan is as a borderline Cat1/Cat 2 is an exception.



Anyway, just trying to keep hope alive for a no school day in the HEB ISD next week...

[cctxhurricanewatcher]

Would any wintry precip...even a coating....result in delayed school openings or closures in houston? People in the north would scoff at that....but it is all relative. When temps got below 40 (widespread...even beaches) a few years back here in south florida (with clear skies), school openings were delayed till noon or so. Now that would give a chuckle to folks from 'anywhere else'!

I'd argue that extra-tropical (Canadian speak: post-tropical) transition was well underway at landfall, just judging from the satellite. Not saying it wasn't still a TC, just that it had started the process. But Juan is as a borderline Cat1/Cat 2 is an exception.



Anyway, just trying to keep hope alive for a no school day in the HEB ISD next week...

Kind of like we chuckle when they issue heat advisories for a low 90 degree day up there....