February 1-5, 2011 Arctic Blast/Winter Storm Discussion

[randybpt]

One thing many have not brought up is the lack.of snow cover to our north. This is going to make a difference allowing any cold air to modify more then if we had more to our north.

[srainhoutx]

The 00Z ensembles look mighty chilly across the Lone Star State...

[srainhoutx]

I know some have seen and mentioned the UKMET, so here is what that model offered over night...

[txflagwaver]

Calm weather today and Friday before big changes this weekend and early next week.

Weak cold front has passed across the region overnight and will help to reinforce the nice late January weather in place. Winds will swing around to the SE on Friday and begin to return moisture to the region ahead of an upper level low off of Baja this morning. This system will track eastward reaching NW Mexico tonight and into SW TX by late Saturday. Southerly flow induced by pressure falls over W TX will pump moisture northward with PWS values approaching the 1.2-1.4 inch range by late Saturday evening. Increasing lift on a 100kt jet streak and a returning warm front bode well for showers/thunderstorm formation Saturday afternoon/evening over south and south-central Texas spreading into SE TX in the overnight hours. Warm front may reach the coastal sections along a line from Victoria to Wharton to Houston by early Sunday allowing an unstable warm sector south of this boundary. 0-6km shear profiles are strong for the coastal bend region into the southwestern sections of SE TX around Matagorda Bay, but overall instability will be lacking with only 500J/kg of CAPE and models do show capping above the surface suggesting storms that develop will be elevated and have a hard time tapping into any “potential” low level instability. A few strong thunderstorms will be possible late Saturday night into early Sunday morning south of a line from Victoria to Columbus to Liberty. As of now will keep any severe threat confined to the offshore areas where best moisture is found and also in line with SPC Day 3 forecast reasoning.

This system looks fairly wet with widespread rainfall amounts of .50 to 1.5 inches across south TX into SE TX. Areas of stronger storms and any training could get more rainfall than current QPF suggests and would expect any of these locations to be along or south of US 59.

Early Next Week:
At last models are finally starting to come to some kind of agreement on the weather for next week. Very cold air mass over Canada currently will begin to head southward this weekend as the upper level flow along the US west coast buckles. Powerful arctic frontal boundary will be generated and begin to surge southward down the front range as a large 1050mb high pressure cell drops southward into the northern plains. Frigid air mass will reach the panhandle early Monday and plow southward across the state pushing off the coast late Monday/early Tuesday. Temperatures in the 60’s on Monday will fall rapidly into the 30’s behind the front with the freezing line progressing south into SC TX and the northern parts of our area early Tuesday.

Big issue comes from additional upper level energy digging into the SW US and carving out a trough over New Mexico resulting in lifting of a moist air mass over the cold arctic dome. Appears this trough will eject across the region sometime in the Tuesday night/Wednesday time period resulting in a chance of precipitation. Forecast soundings for late Tuesday afternoon show the critical thickness lines for different P-types extending from Del Rio to Victoria to just north of Houston. The pattern does appear favorable for some kind of winter weather event over parts of Texas Tuesday-Wednesday next week with chances for freezing rain, sleet, snow, and just rain. Way too early to tell what areas will be impacted and how far south the freezing line and freezing/frozen precipitation will be as the models are just now starting to come into agreement. One other point to make it that if the surge of cold air is stronger it may result in less moisture to work with and lower chances for precipitation, but much colder overnight temperatures including the potential for a hard freeze. Stay tuned!

[harpman]

Let me pose a question here. The 1989 outbreak was something I will never forget. We closed our office at lunch time and what usually is a five minute drive home for me tuned into almost an hour with the snow and sleet falling. We had over an inch of snow on top of all the sleet that had fallen before it changed over. I don't remember if you guys in Houston had snow with that event.

What were the dynamics of that system? I ask because that was extremely cold air, yet we managed to get a gulf low to form which threw the moisture up and over the cold air. Was anyone around back then to follow this event? Wxman57, Srain?

[srainhoutx]

Let me pose a question here. The 1989 outbreak was something I will never forget. We closed our office at lunch time and what usually is a five minute drive home for me tuned into almost an hour with the snow and sleet falling. We had over an inch of snow on top of all the sleet that had fallen before it changed over. I don't remember if you guys in Houston had snow with that event.

What were the dynamics of that system? I ask because that was extremely cold air, yet we managed to get a gulf low to form which threw the moisture up and over the cold air. Was anyone around back then to follow this event? Wxman57, Srain?

I was here for 83 and 89 as well as many of our older members (hush you mature folks ). I believe wxman57 was here for 89.

[wxman57]

After looking at the overnight runs, I'm now quite confident that we really don't know just what will happen next week. There will be some cold air - don't know how cold yet, and possibly some winter precip - don't know where yet. GFS and Euro indicate frozen precip to our north (northern Hill Country to Dallas and eastward) but the air looks too "warm" for anything here.

The only thing to do is to wait another 3-4 days for clarification.

[wxman57]

I was here for 83 and 89 as well as many of our older members (hush you mature folks ). I believe wxman57 was here for 89.

I took a job here in Houston in May of 1980. I was up in College Station (and living at my father's house in Ft. Worth) from 1977-1980. Before that, I was in Lafayette, Louisiana where I was born. So I've been here in Houston for quite a few years (31).

[tireman4]

Srainhoutx:

I was here for 83 and 89 as well as many of our older members (hush you mature folks ). I believe wxman57 was here for 89. [/quote]

Hey, I like that. Mature folks. Yes, I was here in 83....and 73...and the 77 ice event......I missed 89, though. I was in Raleigh, North Carolina. My first winter there, February 1987....12 inches of ice and sleet ( mostly sleet). Started at 10 am and ended at midnight. My trial by fire ( or ice) if you will.

[srainhoutx]

I had forgotten you arrive here in Houston in 1980, wxman57. They say the memory is the first thing to go as you get older, you know... Don't remind me about 73, tireman4. I've been longing for a repeat of that event for way too many years.

[tireman4]

I had forgotten you arrive here in Houston in 1980, wxman57. They say the memory is the first thing to go as you get older, you know... Don't remind me about 73, tireman4. I've been longing for a repeat of that event for way too many years.

Mature, srain...Mature....

[harpman]

I didn't mean to go off topic here. I was just curious as to what was the set up that gave us the moisture with that bitterly cold air in 1989.

[wxman57]

I didn't mean to go off topic here. I was just curious as to what was the set up that gave us the moisture with that bitterly cold air in 1989.

Here's a good site to check past patterns:
http://www.meteo.psu.edu/~gadomski/NARR/1989.html

I believe the maps are derived from the 00hr initialization data for each time period. Look around December 18th-20th, 1989 for setup for the December 23rd to Christmas cold. Here's the map for the coldest day of the event (Dec 23) where IAH reached 7 degrees:

[harpman]

Great, thanks!

[cristina99]

So, it's going to get cold. When we will know just how cold? I wouldn't mind some winter precip - I was in high school in 1989 - and don't remember much about that ice event. I do remember one in mid 1990s - the ice looked like snow, but it was so dangerous. And I know these things can be surprises - maybe it's setting up like that.

[srainhoutx]

So, it's going to get cold. When we will know just how cold?

We should begin to 'see' the air mass in Western Canada sometime later tomorrow. The Polar Vortex is just now starting to drop S from the N Pole and that will usher in that Arctic air mass along it's western flank along with some Upper Level Energy...

[perk]

Let me pose a question here. The 1989 outbreak was something I will never forget. We closed our office at lunch time and what usually is a five minute drive home for me tuned into almost an hour with the snow and sleet falling. We had over an inch of snow on top of all the sleet that had fallen before it changed over. I don't remember if you guys in Houston had snow with that event.

What were the dynamics of that system? I ask because that was extremely cold air, yet we managed to get a gulf low to form which threw the moisture up and over the cold air. Was anyone around back then to follow this event? Wxman57, Srain?

I remember that event, i live just south of Houston in Richmond and we got sleet and freezing rain.Ice everywhere,roofs, driveways, streets you name it.

[srainhoutx]

The 12Z GFS suggests the Arctic boundary will be S of the US/Canadian on late Sunday pushing S into the Northern Rockies/N Plains. That model also suggests a robust Upper Air disturbance sliding SE from the Pacific NW as well @ hour 84...

[srainhoutx]

By hour 102, the GFS suggests the Arctic boundary is entering the TX Panhandle and diving S. Snow breaks out across the Central Plains and is heading S as well. Also our robust short wave is pushing S along the trough into Southern CA/AZ...

[unome]

I don't like cold weather

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