Texas winter wx thread (2009-2010)

[msstateguy83]

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[srainhoutx]

Just a word of caution. That map will change as future guidance comes in just as the image I posted yesterday of Storm Tracks. Just too soon to know where and how this will all play out IMHO.

[wxman57]

The NAM was terrible with the last event. Even the morning of the big snow in Dallas, it showed the air aloft was too warm for snow.

[iorange55]

The NAM was terrible with the last event. Even the morning of the big snow in Dallas, it showed the air aloft was too warm for snow.

I was meaning to ask all this winter it seems as if the NAM is always weaker with the cold, and the storm. It always looks disorganized on there, and hardly even a storm at all. Has it always been this way, or is it just this winter?

[wxman57]

For those of you in the Houston area, here's the 06Z GFS. Has most precip ending with the temp at IAH of 35F. That would be warmer than the Dec. 4th event. Of course, this is assuming the 06Z GFS has a perfect temperature forecast for 72-84 hours out.



So it has most precip ending between 6pm and 9pm Tuesday. Now let's take a look at the projected vertical profile as per the 06Z GFS for Tuesday to trace the changeover from rain to sleet to snow. First, 3pm Tuesday. On this chart, I've marked the freezing line in blue. The red line is temperature, the green line is dew point. Clouds and precip occur when the red and green lines are close together (high relative humidity). The 3pm chart shows the red/green lines touching from just above 700mb (10,000ft) to about 550mb (14,000ft or so). In that area, snow would form and fall.

But as the snow reaches just above 800mb (6500ft) it encounters an area of above freezing temps. The thickness of this warm air layer will determine if the snow has time to melt before reaching colder air farther down. It looks like the warm air is thick enough here to melt the snow into rain. The rain falls a few thousand feet then encounters colder air, cold enough to re-freeze it into sleet. At the surface, a mixture of rain and sleet is seen, possibly mixed with a few surviving snowflakes. Surface temperature is in the 37F range, so no accumulation.

3pm Tuesday GFS forecast sounding:


Let's move on to the 6pm sounding. Major changes occur between 3pm and 6pm. Note that the red and green lines are touching from 500mb to the surface. That indicates a near-saturated column (clouds and precip likely). Also note that the red temperature line has slid left of the freezing line, meaning the whole column is below freezing EXCEPT for the surface, which is at around 34-35F.

This is a snow sounding for Houston at 6pm Tuesday. However, if surface temps are above freezing, then it won't hang around long. For it to stick around, we really need surface temps to be below 32F.

6pm Tuesday GFS forecast sounding:


On to 9pm Tuesday. Note that there is only a very small area at the surface which is above freezing. Also note that the red and green lines are separating. The separating lines means the air aloft is drying out - the precip is coming to an end.

9pm Tuesday GFS forecast sounding:


So, the 6Z GFS does show snow for Houston, but there is a BIG question mark as to if any will accumulate. My instincts say no accumulation. I don't think that the airmass will be quite cold enough early enough. But we could see some nice big flakes in the sky Tuesday late afternoon/evening.

[Ntxw]

I hope wxman gets 5 inches of snow blowing snow too!

[wxman57]

I hope wxman gets 5 inches of snow blowing snow too!

I hope not. You can have it. I'd trade it for a few weeks of 90 degree weather.

[Ntxw]

Not too long now wxman, meteorological spring is right around the corner! Though, punxsutawney phil and the Europeans seem to think you might have to wait a bit longer. (if i recall correctly, the whole groundhog thing originated in Germany? Hm conspiracy anyone?)

Portastorm ought to like 12z GFS

[txagwxman]

Latest 12z Run has the rain/snow line just to the NW of Houston...College Station/Austin should pick up 1-3" if this happens. But if it does snow in Houston it will be just quick change at the last minute (as WXMAN57 suggest).

[txagwxman]

Nice sounding over Waco.

[txagwxman]

Magnolia, TX would support snow Tuesday evening.

[srainhoutx]

That getting mighty close to our area txagwxman...

[Portastorm]

The 12z GFS looks mighty friendly to the Austin area.

[txagwxman]

:uarrow: That getting mighty close to our area txagwxman...

Yes...at least I can drive to see it...Austin will get 3" if this verifies. Portastorm should be happy.

[Portastorm]

:uarrow: That getting mighty close to our area txagwxman...

Yes...at least I can drive to see it...Austin will get 3" if this verifies. Portastorm should be happy.

It has been seven years since we have seen 3 inches of any kind of wintry mix or snow. Seven LONG years!!

May the GFS trend continue.

[gofrogs2]

What else is showing.

[Extremeweatherguy]

Here is a look at the 12z snow depth maps..

NAM - peak accumulations at around 75 hrs out:


GFS - peak accumulations at around 84 hrs out:


The NAM shows a fairly light event, with only around 1-2 inches of accumulation around the Red River region. The GFS, on the other hand, absolutely pounds central Texas, with some areas seeing upwards of 6 inches of snow! Meanwhile, areas further north get very little in the way of accumulation according to the 12z GFS. Dallas would be lucky to get more than a dusting and the Red River region would see nothing.

[katheria]

Portastorm,

ill get the biggest fan i can and blow it all down your area
id love another round of snow, but you know what id rather you get it we had our snow heaven this year...

[iorange55]

I'd be fine with getting 1 to 2 inches while Austin and Waco get 5 or 6 inches. But I'd also hope San Antonio at least sees snow whether it accumulates or not. I know it's very hard for it to snow in San Antonio, but I feel bad ever since earlier in the year when it looked like it was going to, and my friend down there got excited, but nothing happened.


Hopefully this time they see something, at least. If nothing more than flakes falling down.

[gofrogs2]

Trust me the axis of good snow will be somewhere along I 20 iam not buying the southerntrack.