SE TX/SW LA Winter WX - 2011-2012

[vbhoutex]

43f here at the house. Also lower than I expected at this time. I have to wonder if we will have a freeze though with thickening clouds moving in from the NW. HIgh was 55f which was a little lower than I expected, but we had clouds move in earlier than I thought they would too.

edit @ 9:20 pm- down to 37f and clear skies. gonna be well below freezing unless it clouds back up.

[srainhoutx]

A good 6 hour below freezing here overnight with some light frost. Coastal areas may well see some light rain. We will see just how far N into the Houston area this can make it...along and SE of the HYW 59 corridor appears the most likely areas to see any chance of rainfall...

HPC QPF Discussion:

...SHRTWV DIGGING SEWD FM THE CNTRL ROCKIES..

THIS SYSTEM HAS VERY LIMITED MSTR AVBLTY AND THEREFORE EXPECT THE
SWATH OF PCPN ASOCTD WITH THE DIGGING PROCESS FROM THE CNTRL
PLAINS EWD TO THE LWR MS VLY WILL BE VRY LGT. HOWEVER BY THE 2ND
HALF OF THE PD...THERE WILL BE A SHORT PD WHEN A LLVL MSTR FETCH
FM THE WRN GULF OF MEXICO WILL BE AVBL TO SUPPORT MORE WIDESPREAD
AND HEAVIER SHWRS INVOF OF SERN TX AND SWRN LA. MODEL GUIDANCE IN
GNRL AGREEMENT ON THE LATTER SCENARIO AND OPTED FOR A BLEND OF
GUIDANCE HERE.

[vbhoutex]

Strange that you had 6 hours below freezing while we never got below freezing at my house. Low here was 32.8f. I fully expected what you got with the temps dropping like they were last night. Any cloudiness affecting me and CAA would probably affect you also so I'm wondering what happened.

[Agua]

Strange that you had 6 hours below freezing while we never got below freezing at my house. Low here was 32.8f. I fully expected what you got with the temps dropping like they were last night. Any cloudiness affecting me and CAA would probably affect you also so I'm wondering what happened.

Could be he's in a location that normally has very localized lower temps due to geography. My old family home is in a spot like that and best I can tell it is due to proximity to a river and in a valley. Temps are generally 1-3 degrees cooler than locations 1/2 mile away.

[srainhoutx]

Strange that you had 6 hours below freezing while we never got below freezing at my house. Low here was 32.8f. I fully expected what you got with the temps dropping like they were last night. Any cloudiness affecting me and CAA would probably affect you also so I'm wondering what happened.

We had clear skies up here when I went to bed last night David, and no wind. It appears that areas from Conroe to Hooks to the Katy Prairie were in an ideal spot for radiational cooling.

[southerngale]

We were below freezing for many hours here, too. Had a low of 28° and white frosting this morning. Just makes me want snow...

[srainhoutx]

HGX just increased my rain chances to 70% after midnight with lows near 40 degrees. Any rainfall is very much needed and I will be happy!

[wxman57]

We were below freezing for many hours here, too. Had a low of 28° and white frosting this morning. Just makes me want snow...

Forecast sounding from the 12Z GFS does indicate some snow aloft over you tomorrow morning, southerngale. However, note that the freezing level is way up around 7000-8000 ft. Below that it's above-freezing temps all the way to the ground. It would be hard for snow to survive that long in above-freezing temps. How about some ice-cold rain? Not far to your northeast, however (north of LCH), the vertical profile could be cold enough to allow for a few flakes to reach the ground.

[southerngale]

hmmm... now you're gonna get me hoping for a miracle, wxman57. lol I noticed that NWS had a low of 35° for me tonight with a 50% chance of rain. They're often a little too warm so the thought crossed my mind, but I remembered your soundings from last year and figured it would be too warm aloft.

Is that sounding for Beaumont or down at the airport? I guess it wouldn't be much different just west of Beaumont, along Hwy. 105, but I notice my latitude is higher than that sounding. Yeah, I'm grasping at straws.

[wxman57]

hmmm... now you're gonna get me hoping for a miracle, wxman57. lol I noticed that NWS had a low of 35° for me tonight with a 50% chance of rain. They're often a little too warm so the thought crossed my mind, but I remembered your soundings from last year and figured it would be too warm aloft.

Is that sounding for Beaumont or down at the airport? I guess it wouldn't be much different just west of Beaumont, along Hwy. 105, but I notice my latitude is higher than that. Yeah, I'm grasping at straws.

For that sounding, I just used the "twister" site and clicked on the map near Beaumont. For a sounding closer to your location, use this site:

http://ready.arl.noaa.gov/READYcmet.php

You can input your exact lat/lon in that interface and even generate a sounding loop.

I expect that the lower levels will be too "warm" there in Beaumont/Port Arthur for anything but light rain. Still can't 100% rule out the chance of a few flakes surviving to reach the ground. Sleet would seem unlikely given the vertical profile.

[southerngale]

Cool, thanks for the link. I don't know if I did it right, but I got this.

[wxman57]

I'm not sure what you plotted, southerngale. Here's a plot from the same website that goes all the way to the surface. Valid 9Z (3am) tomorrow. Note that the temperature curve (red) crosses the 0C line near 800mb (near 6000 ft).

Remember that you need to pick the plot time. You plotted the 00hr sounding (12z today). I plotted the 21hr forecast (9Z tomorrow).

See here:

[Ptarmigan]

I think it is possible that Houston saw below 0 temperatures. Officially, Houston never saw below 0 when records were kept. However, I think it is very possible that Houston did see below 0 temperature in areas there were no weather stations and development. I think most likely in the January 1886 and February 1899 freeze, which was a very deep freeze. Both 1886 and 1899 freeze caused Galveston Bay to freeze up.

Why I think that? Back than Houston was not developed and largely forested or open land. There are also other big freezes that occurred from 1850 to 1890. Those freezes could of produced below 0 for Houston during that time.

NCDC: Extreme Events of Feb 1899
http://www.ncdc.noaa.gov/oa/climate/ext ... s0299.html

History of Freezes in the Lower Rio Grande Valley, Part II 1895-1962
http://www.raingardens.com/psst/articles/artic02.htm

A History of Severe Freezes in the Lower Rio Grande Valley -- Part III
http://www.raingardens.com/psst/articles/artic03.htm

[srainhoutx]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
312 PM CST TUE DEC 7 2010

.DISCUSSION...
STRATO CU DECK AROUND 5KFT CONTINUES TO SPREAD NE ACROSS SE TX
THIS AFT. EXPECT MOISTURE LEVELS TO CONTINUE TO INCREASE THIS
EVENING WITH RAIN BEGINNING TO DEVELOP NEAR THE COAST AROUND
MATAGORDA BAY EARLY THIS EVENING...THEN SPREADING NORTH AND
INLAND DURING THE EVENING HOURS. MAY SEE SOME TSTM ACTIVITY WELL
OFFSHORE WHERE 60+ DW PTS WILL BE LOCATED. HAVE TAPERED POPS FROM
THE COAST TO NW AREAS TONIGHT. THE LATEST MODEL GUIDANCE IS
INDICATING WIDESPREAD SHWR ACTIVITY NEAR THE COAST BY
MIDNIGHT AS THE SFC LOW FORMS IN THE NW GULF. DECIDED TO BUMP
POPS UP FOR TONIGHT CLOSER IN LINE WITH THE 12Z GFS. WILL HAVE SOME
CHC POPS CONTINUING NEAR THE COAST WED MORNING...WITH ALL PRECIP
ENDING BY LATE MORNING.

ACROSS FAR NORTHERN AREAS AND LATE TONIGHT LIGHT RAIN MIGHT
BRIEFLY MIX WITH LIGHT SNOW AS THE SFC WET BULB TEMP IS EXPECTED
TO BE IN THE MID 30S. SFC TEMPS WILL BE SLIGHTLY ABOVE FREEZING...
SO IF THIS DOES OCCUR...NO ACCUM IS EXPECTED. MENTIONED THIS
POSSIBILITY FOR HOUSTON AND TRINITY COUNTIES.

[jasons2k]

Latest from Jeff Lindner:

Newest 12Z guidance suggests some potential for light rain to mix with light snow tonight over the far northern counties of SE TX mainly from College Station to Lufkin. Afternoon dewpoints continue to run in the 20’s and 30’s across much of the northern ½ of SE TX and with the onset of rainfall this evening. Surface wet bulb temperatures are running in the mid 30’s over the northern sections of SE TX and once precipitation begins to fall the surface temperature will quickly cool toward the wet bulb temperature due to evaporative effects within the dry low level air mass. While surface temperatures will remain above freezing there is some potential for snow to mix with the rain. Profiles are very marginal for snow to reach the ground and most if not all will melt prior to reaching the surface, although would not be surprised to see a few flakes in the Livingston and Crockett areas late tonight. No accumulation is expected in SE TX although some light accumulation may occur over portions of N and NE TX.

Additionally, 12Z guidance has come in a little more aggressive with coastal surface low formation and rain chances/QPF for tonight into Wednesday AM. Will give the amounts a slight bump into the .25-.50 inch range for locations south of I-10 and possibly as much as .75 of an inch near the coast. Widespread coverage will require high rain chances overnight (60-70%) while amounts will on the low side.

[PTrackerLA]

Wxman, here is the sounding for LFT overnight:


does the wet bulb line indicate a better chance of seeing some flurries overnight here as I see it cross the 0 degree line well under 850mb? As an amateur that enjoys checking out these soundings during the winter, I'd assume that flakes are possible but the big problem will be lack of moisture.

P.S. Just peaked at the latest 18z GFS at 18 hrs and it looks rather interesting...

[wxman57]

Wxman, here is the sounding for LFT overnight:
http://www.twisterdata.com/data/tmp/scr ... .0000W.png]

does the wet bulb line indicate a better chance of seeing some flurries overnight here as I see it cross the 0 degree line well under 850mb? As an amateur that enjoys checking out these soundings during the winter, I'd assume that flakes are possible but the big problem will be lack of moisture.

Note where the red (temp) and green (dew point) lines sort of merge around 750MB. That's the base of the clouds/precip. Also note that this occurs in sub-freezing air. So that sounding indicates clouds and possibly precip forming in sub-freezing air but with about 6000 ft of above freezing air below the cloud base. Precip could start out as snow and melt on the way down. Now as precip falls, it will tend to cool the air column below the sub-freezing air. But with not much precip falling, I don't know if it'll be enough for snowflakes to reach the ground.

[southerngale]

I'm not sure what you plotted, southerngale. Here's a plot from the same website that goes all the way to the surface. Valid 9Z (3am) tomorrow. Note that the temperature curve (red) crosses the 0C line near 800mb (near 6000 ft).

Remember that you need to pick the plot time. You plotted the 00hr sounding (12z today). I plotted the 21hr forecast (9Z tomorrow).

See here:
http://myweb.cableone.net/nolasue/sounding.gif

http://ready.arl.noaa.gov/readyout/44248318_profile.gif

Ahhh, ok. I didn't change the plot time when I did it. Thanks.

So is that sounding for here showing a possibility of a few flakes? I'm trying to understand these.

[Ntxw]

Ahhh, ok. I didn't change the plot time when I did it. Thanks.

So is that sounding for here showing a possibility of a few flakes? I'm trying to understand these.

It shows the upper atmosphere is capable of it from wxman's soundings but possibly not heavy enough precip to bring the temps down near the ground to colder levels for the snowflake's survival. You'll have to keep an eye on the radar and what happens in places nearby to see if the precip shield is extensive enough to drag the cold and snow aloft down to your viewing peasure .

[PTrackerLA]

Well definitely something to look out for first thing in the morning! Good luck to both of us SG lol!