More cold air on the way next week!?

[srainhoutx]

Okay, what am I doing wrong as far as posting images?

Post the link and leave out the image code for now. We'll be working on this tonight.

[Portastorm]

Looks like the core of the upper low will pass just to our north...

http://wxweb.meteostar.com/models/noaap ... te/SCR/WV/

Not sure how you're getting that. Looks to me like it's still digging southeast. At this rate it will go south of Houston.

[srainhoutx]

Looks like the core of the upper low will pass just to our north...

http://wxweb.meteostar.com/models/noaap ... te/SCR/WV/

Not sure how you're getting that. Looks to me like it's still digging southeast. At this rate it will go south of Houston.

The trend has been along the Coastal Bend and on E.

[TexasMetBlake]

Well what you want is for the low to track right overhead where the coldest pocket of air is.

Here's the 12z GFS 850 temps...gfs brings us below freezing after the precip exits stage right.

http://wxmaps.org/pix/avnmr.850.html

[TexasMetBlake]

Looks like the core of the upper low will pass just to our north...

http://wxweb.meteostar.com/models/noaap ... te/SCR/WV/

Not sure how you're getting that. Looks to me like it's still digging southeast. At this rate it will go south of Houston.

The trend has been along the Coastal Bend and on E.

<Looks again>

[snowman65]

Well what you want is for the low to track right overhead where the coldest pocket of air is.

Here's the 12z GFS 850 temps...gfs brings us below freezing after the precip exits stage right.

http://wxmaps.org/pix/avnmr.850.html

One says north, one says south, so let's just say it will pass right over us, just like we want

[TexasMetBlake]

Looks like the core of the upper low will pass just to our north...

http://wxweb.meteostar.com/models/noaap ... te/SCR/WV/

Not sure how you're getting that. Looks to me like it's still digging southeast. At this rate it will go south of Houston.

The trend has been along the Coastal Bend and on E.

<Looks again>

[TexasMetBlake]

NOW I SEE IT! Sorry, looked at the wrong cotten picken thing. Here's the link. It's like a bowling ball...

http://wxweb.meteostar.com/models/noaap ... UMBLOOP=10

[srainhoutx]

NOW I SEE IT! Sorry, looked at the wrong cotten picken thing. Here's the link. It's like a bowling ball...

http://wxweb.meteostar.com/models/noaap ... UMBLOOP=10

Same link...different view...

http://wxweb.meteostar.com/models/noaap ... te/SCR/IR/

[tireman4]

Ok, in laymen terms....(Srainhoutx and Candy Cane and Portastorm), what does that mean for the Houston Metro area? Does the 18z NAM show snow at Hooks Airport? Is this going to suprise many folks?

[TexasMetBlake]

Ok, in laymen terms....(Srainhoutx and Candy Cane and Portastorm), what does that mean for the Houston Metro area? Does the 18z NAM show snow at Hooks Airport? Is this going to suprise many folks?

The NAM shows 850 temps cooling to freezing before the event is over as heights fall and the low pushes east. If the 18z varified, it looks like snow would be possible for most of the metro--especially north and east. That's a big IF.

[TexasMetBlake]

Keep in mind that the GFS does not agree...

IAH = rain

http://68.226.77.253/text/1DegGFS/GFS_Kiah.txt

CXO (conroe) = rain

http://68.226.77.253/text/1DegGFS/GFS_Kcxo.txt

UTS (huntsville) = Snow

http://68.226.77.253/text/1DegGFS/GFS_Kuts.txt

[wxman57]

The following discussion pertains to IAH - northern Houston.

NAM has been trending warmer than the GFS in many areas, but apparently not in Houston. 18Z not all in, but 12Z forecasts quite warm air between the surface and 10,000ft (low 40s) until around 3am Friday. Beyond that, it shows significant cooling to below freezing aloft. Unfortunately, it also forecasts precip ending around then. So, according to the NAM, there may be a period of about an hour or so between 3am-6am Friday when a few snowflakes may fall. But moisture will be quite limited after the upper low passes late tonight and temps will be above freezing at the surface, so accumulations are not forecast.

GFS is very similar to the NAM in holding warmer air aloft (above-freezing) until around 3am Friday. Seems to show only a tad more moisture around then. Between 3am and 8am it's possible that a few snowflakes may survive to reach the ground. But they won't last long with the surface temperature around 34-36 degrees.

Oh, and careful about interpreting those charts with a valid time and precip. That precip occurs up to 6 hours BEFORE the valid time of the chart. Just because there is "green" over Houston while the 18Z NAM shows it being cold enough to snow doesn't mean that there is still precip at that time. The precip could have ended hours before the chart valid time.

[srainhoutx]

The fly in the ointment is the Coastal Low near Corpus...

http://www.srh.noaa.gov/tropical/satpix ... 4_loop.php

[TexasMetBlake]

The following discussion pertains to IAH - northern Houston.

NAM has been trending warmer than the GFS in many areas, but apparently not in Houston. 18Z not all in, but 12Z forecasts quite warm air between the surface and 10,000ft (low 40s) until around 3am Friday. Beyond that, it shows significant cooling to below freezing aloft. Unfortunately, it also forecasts precip ending around then. So, according to the NAM, there may be a period of about an hour or so between 3am-6am Friday when a few snowflakes may fall. But moisture will be quite limited after the upper low passes late tonight and temps will be above freezing at the surface, so accumulations are not forecast.

GFS is very similar to the NAM in holding warmer air aloft (above-freezing) until around 3am Friday. Seems to show only a tad more moisture around then. Between 3am and 8am it's possible that a few snowflakes may survive to reach the ground. But they won't last long with the surface temperature around 34-36 degrees.

Oh, and careful about interpreting those charts with a valid time and precip. That precip occurs up to 6 hours BEFORE the valid time of the chart. Just because there is "green" over Houston while the 18Z NAM shows it being cold enough to snow doesn't mean that there is still precip at that time. The precip could have ended hours before the chart valid time.

That's true. Here is the gfs. Do you happen to have a better link for 850 temps, WXMAN?

http://wxweb.meteostar.com/sample/sampl ... ?text=kiah

[wxman57]

That's true. Here is the gfs. Do you happen to have a better link for 850 temps, WXMAN?

http://wxweb.meteostar.com/sample/sampl ... ?text=kiah

If I'm out of the office (or sometimes here at work), I really like this Air Resources Laboratory website. It's the same site I use to get the raw data for the meteograms, but it also makes excellent sounding loops:

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

Though these soundings take a bit of meteorological experience to read, they do make it clear when the column of air overhead would be cold enough for snow and how much moisture is still available. You can make a plot out to any time period, any size, animated GIF or Java (Java allows you to stop the animation and step through the loop slowly). Here's an animation of the 12Z GFS forecast for IAH. I'll just post the link so we won't be hitting their server for the animation every time someone loads this page:

http://ready.arl.noaa.gov/readyout/3100 ... f_anim.gif

When the red and green lines are close together that indicates clouds and/or rain. When the red line is to the left of the diagonal 0C temperature line between the surface and aloft (say up to 10,000 ft), that indicates the air is cold enough for snow. Note when the red and green lines begin to separate (9Z-15Z). That indicates precip ending and clouds thinning - just when temps aloft are starting to get cold enough for snow.

[srainhoutx]

Thanks wxman57.This is what makes our board so friendly and informative.

[tireman4]

Helps also to have Pro Mets. Very great asset.

[Aquaria]

I am getting so disappointed. Where is the snow in Tyler???? Are we doomed to rain the rest of the night?

[srainhoutx]

For our neighbors to the E...

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE LAKE CHARLES LA
324 PM CST THU FEB 11 2010

...MAJOR WINTER STORM TO AFFECT THE AREA TODAY INTO TOMORROW...

.WIDESPREAD RAIN ASSOCIATED WITH A MAJOR WINTER STORM WILL
CONTINUE TO COVER SOUTHEAST TEXAS AND SOUTHERN LOUISIANA. THE
RAIN MAY BE MIXED WITH SLEET AT TIMES FOR THE REMAINDER OF THIS
AFTERNOON. TONIGHT...THE RAIN AND SLEET MIXTURE IS EXPECTED TO
CHANGE TO ALL SNOW ACROSS CENTRAL LOUISIANA...WHILE A WINTRY MIX
WILL CONTINUE ACROSS THE LAKES REGION OF SOUTHEAST TEXAS. AREAS
NORTH OF THE HIGHWAY 190 CORRIDOR ARE EXPECTED TO SEE SNOW
ACCUMULATIONS RANGING FROM A TRACE TO 2 INCHES...WHILE MORE
SIGNIFICANT SNOW ACCUMULATIONS OF 2 TO 4 INCHES WITH LOCALLY
HIGHER AMOUNTS ARE LIKELY ACROSS CENTRAL LOUISIANA. SNOW MAY
BRIEFLY BE HEAVY LATE TONIGHT AS THE MAIN UPPER LEVEL SYSTEM MOVES
ACROSS THE REGION...WITH SNOWFALL RATES UP TO 1 INCH PER HOUR
POSSIBLE AFTER MIDNIGHT. SNOW WILL FIRST STICK TO VEGETATION AND
ELEVATED SURFACES THURSDAY EVENING BEFORE ACCUMULATING ON SURFACE
ROADWAYS THURSDAY NIGHT...WITH POTENTIAL MAJOR IMPACTS TO AREA
TREES AND POWER LINES DUE TO THE HEAVY WET NATURE OF THE SNOW. ALL
WINTER PRECIPITATION IS EXPECTED TO COME TO AN END ON FRIDAY.

LAZ027>029-120530-
/O.EXT.KLCH.WS.W.0001.100212T0000Z-100212T2200Z/
VERNON-RAPIDES-AVOYELLES-
INCLUDING THE CITIES OF...LEESVILLE...ALEXANDRIA...MARKSVILLE
324 PM CST THU FEB 11 2010

...WINTER STORM WARNING NOW IN EFFECT UNTIL 4 PM CST FRIDAY...

THE WINTER STORM WARNING IS NOW IN EFFECT UNTIL 4 PM CST FRIDAY.

* TIMING: A MIX OF RAIN AND SLEET EARLY THIS EVENING WILL
CHANGEOVER TO ALL SNOW BY MIDNIGHT AND PERSIST THROUGH FRIDAY
MORNING.

* MAIN IMPACT: SNOW ACCUMULATION OF 2 TO 4 INCHES...WITH LOCALLY
HIGHER AMOUNTS.

* OTHER IMPACTS: SNOW MAY BE HEAVY AT TIMES LATE TONIGHT INTO
EARLY FRIDAY MORNING...WITH SNOWFALL RATES UP TO 1 INCH PER HOUR
POSSIBLE. THE HEAVY WET NATURE OF THE SNOW MAY CAUSE SIGNIFICANT
DAMAGE TO TREES AND POWER LINES ACROSS CENTRAL LOUISIANA.