More cold air on the way next week!?

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sleetstorm
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Portastorm wrote:
sleetstorm wrote:Why would that wave of low pressure warm the atmosphere up in the mid and upper levels, Portastorm, Mr. T, srainhoutx, wxdata?
Sleet, it will be pumping warm gulf air over our heads ... and slowly but surely working its way down to the surface so that the entire air column is saturated.
That was not the way that is was during last December fourth's snowstorm or December tenth of 2008? So what is different about this time?
sleetstorm
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The wave of low pressure that generated the snowstorm of December tenth 2008 was completely over land.
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wxman57
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This passing feature doesn't have nearly the cold air aloft that the December 2008 feature did. As the wave approaches, south and southeasterly winds in the lower levels (just above the surface) will advect warmer air aloft. Too warm for any significant winter precip here. Once the low/wave axis passes, the air aloft will cool. But the moisture will decrease very quickly after the low passes.

So, for Houston, lots (and lots) of cold miserable rain from tomorrow evening through late Thursday night, possibly mixed with a few sleet pellets at times.

But winter isn't over. Long-range guidance suggests some very cold air moving south out of Canada late next week, and that cold pattern may persist for a while. The southern stream will probably remain active. It's just a matter of timing as far as any future winter precip chances here this month.
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wxman57
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sleetstorm wrote:
Portastorm wrote:
sleetstorm wrote:Why would that wave of low pressure warm the atmosphere up in the mid and upper levels, Portastorm, Mr. T, srainhoutx, wxdata?
Sleet, it will be pumping warm gulf air over our heads ... and slowly but surely working its way down to the surface so that the entire air column is saturated.
That was not the way that is was during last December fourth's snowstorm or December tenth of 2008? So what is different about this time?
The difference is in the vertical profile of the atmosphere over Houston ahead of each feature. The air aloft was significantly colder ahead of the 2008 system, enough so that the low-level warm advection wasn't enough to bring the air column aloft above freezing.
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C2G
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Great, more cold, cloudy, wet weather.
I have never wanted spring and summer as much as this year.
You know it would be almost tolerable with a snowflake now and then..........but noooooo.
sleetstorm
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wxman57 wrote:This passing feature doesn't have nearly the cold air aloft that the December 2008 feature did. As the wave approaches, south and southeasterly winds in the lower levels (just above the surface) will advect warmer air aloft. Too warm for any significant winter precip here. Once the low/wave axis passes, the air aloft will cool. But the moisture will decrease very quickly after the low passes.

So, for Houston, lots (and lots) of cold miserable rain from tomorrow evening through late Thursday night, possibly mixed with a few sleet pellets at times.

But winter isn't over. Long-range guidance suggests some very cold air moving south out of Canada late next week, and that cold pattern may persist for a while. The southern stream will probably remain active. It's just a matter of timing as far as any future winter precip chances here this month.
Okay, thank you, wxman57. Now, how many hours of sleet, snow, or rain snow mix could southeast Texas get prior all it turns to liquid from around noon to evening? And how many hours during the evening before all of the precipitation exits Texas?
poobear55
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what's up? no replies since 7:37. trying to post to see if something is wrong with forum.
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after reading everyone's post this afternoon i thought this event was close but no cigar. then i watched the news tonight and gene norman seemed to be hyping or teasing us with a better chance for some type of frozen precip. so i got on line to see if something had changed. to get the real scoop. i am surprised at the lack of activity. i guess it really is a non-event.
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poobear55 wrote:after reading everyone's post this afternoon i thought this event was close but no cigar. then i watched the news tonight and gene norman seemed to be hyping or teasing us with a better chance for some type of frozen precip. so i got on line to see if something had changed. to get the real scoop. i am surprised at the lack of activity. i guess it really is a non-event.
Since the NAM and GFS has been downers on snow chances here, interest has waned a bit..
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Funny how as some of the models are downplaying the event, some of the local mets, including the fellow from Fox26, are giving the idea an uptick. The fact of the matter is, noone knows for sure about the winter precip. possibilities just yet. Everybody has their own idea, but all of it is just speculation.

Wednesday night will tell us much, but even then things could change as quickly as the night before. That is just how it is down here. You will not find much going on in this forum unless there is more certainty than we have now. Watching the models flip/flop gets old after a while.
poobear55
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Yeah, that seems to be the case here in se tex. winter weather is just to hard to predict. just when you think you have it figured out. mother nature lets you know who is in charge.
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Mr. T
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6z NAM and 6z GFS have trended towards the deeper European solutions (ECMWF, CMC, UKMET), but still not there yet... As such, HGX follows warm outlier GFS again, and this is what you get:

For Brazos County (HGX)
Tonight...Cloudy. A chance of rain in the evening...then rain likely after midnight. Lows in the mid 30s. Southeast winds around 5 mph. Chance of rain 40 percent in the evening increasing to 70 percent after midnight.

Thursday...Rain. Highs in the lower 40s. East winds 5 to 10 mph. Chance of rain 90 percent.

Thursday Night...Cloudy. Rain likely in the evening...then a chance of rain after midnight. Lows in the mid 30s. Northeast winds 10 to 15 mph. Chance of rain 70 percent in the evening decreasing to 30 percent after midnight.



Now, just travel a county north out of the HGX zone and you get this:
For Robertson County (FWD)
Tonight...Cloudy. A slight chance of rain in the evening...then rain and snow likely after midnight. No snow accumulation. Lows in the mid 30s. Southeast winds around 5 mph. Chance of precipitation 70 percent.

Thursday...Rain and snow in the morning...then rain and a chance of snow in the afternoon. Very light to moderate snow accumulations possible on grass and elevated surfaces. Temperatures steady in the mid 30s. East winds 5 to 10 mph. Chance of precipitation near 100 percent.

Thursday Night...Rain and snow in the evening...then a chance of rain and snow after midnight. Lows in the mid 30s. Northeast winds 10 to 15 mph. Chance of precipitation 90 percent.


Nice coordination... The fact that HGX is not even mentioning the chance of some snow or sleet mixing in with the rain across at least northern counties is baffling to me.
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Hints about the future...
HOWEVER RAIN CHANCES REMAIN IN THE PICTURE FOR SUNDAY AS THE UPPER
LEVEL TROF AXIS LINGERS OUT WEST. AS SUCH ANOTHER S/WV PROGGED FOR
THIS TIMEFRAME. AND WHILE THERE ARE CONCERNS WITH AVAILABLE MOIST-
URE...THE PERSISTENCE WITH WHICH MODELS ARE HANGING ONTO THIS DOES
GIVE PAUSE AND WILL LEAVE LOW POPS IN FOR SUNDAY. AS FOR THE LONG-
RANGE FCST...WE ARE ALSO SEEING A LOT MORE CONSENSUS WITH THE IDEA
OF HIGHLY AMPLIFIED RIDGING TO OUR WEST AND THE RESULTANT DEEP NNW
FLOW ALOFT FOR US. THIS SHOULD TRANSLATE INTO INCREASED CHANCES OF
ARCTIC AIRMASSES HEADED THIS WAY...WITH THE OCCASIONAL S/WV OR TWO.41
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Mr. T
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Remember that time the NAM and GFS began to drastically switch over to the Euro, CMC, and UKMET models showing a proper phase with that system out in the West?

OLD 0z NAM friday morning:

Image
Image


New 12z NAM friday morning:

Image
Image

Shifts again towards the Euro, UKMET, and CMC... It looks as though the NAM and GFS have been much too weak with this system and have not properly shown correct phasing with the northern stream as the coastal low develops and pushes off to the east.

Now, I don't know what specific soundings look like for IAH at that period, but there is likely some snow falling across northern areas of SE TX. The NAM still is not quite as strong or cold as the European trio, so today's 12z runs will be very critical to see if we have a developing suprise on our hands.

If the 0z CMC, Euro, or UKMET were to verify, the upper levels would be cold enough to support a changeover to snow over the Houston area as the coastal low scoots on by. 12z NAM is darn close, but it's trying to catch up.
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Mr. T
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Some very awful run to run consistency by the GFS and NAM in the handling of the upper air pattern within the 60 hour time frame here...
Just look at the handling of the NAM of the upper air pattern for friday morning. Bad.

Anyway, here is the 0z CMC I've been reference. It has remained steadfast with the chance of some wintry fun around the area for friday morning for a few runs now...

And, to try to make myself more clear, I'm not talking about accumulating snow or anything right now, just a much better chance at seeing some snow flying through the air around here friday morning... For one thing, surface temperatures would be marginal for accumulation and the system will be moving fast.
sleetstorm
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Thank you, Mr. T., for all of that helpful data and clarity. So if anyone wants any oppotunity at all to feasibly see some snow or sleet mixed in with rain friday morning, here in SE Texas, do not wait until noon to get up because precipitation chances will be going down rather quickly as the day progresses. Right, Mr. T?
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Portastorm
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NWS receiving multiple reports of sleet falling in San Antonio as of 9:30 a.m.
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Mr. T
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sleetstorm wrote:Thank you, Mr. T., for all of that helpful data and clarity. So if anyone wants any oppotunity at all to feasibly see some snow or sleet mixed in with rain friday morning, here in SE Texas, do not wait until noon to get up because precipitation chances will be going down rather quickly as the day progresses. Right, Mr. T?
Yes, that is correct. The NAM is a little slower moving everything out, but we should be dry as friday morning rolls through. Friday overnight is looking interesting.

Look at these differences between the 0z GFS at 6z friday and the 12z GFS at the same time:

OLD 0z GFS midnight friday:
Image

NEW 0z GFS midnight friday:
Image

Look how much lower thicknesses are across the area compared to the previous run. In a word, horrible, HORRIBLE handling of this upper air feature by the NAM and GFS. And yet, the NAM and GFS are STILL slightly warmer than the "European Trio"... Who wants to bet the 18z GFS and NAM come in colder still?


I'm not sure why the NAM and GFS have been completely clueless with this system, while the European Trio (ECMWF, UKMET, CMC) have latched onto this idea of some winter precip over the area since two days ago... I'm also not sure why everyone has been ignoring the model consensus and going with the warmer outlier GFS (which it still slightly is). It's time for the NWS to wake up
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don
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Hmm does make you wonder if we could possibly have another "suprise" snow event? similar to december 2008...
Last edited by don on Wed Feb 10, 2010 11:09 am, edited 1 time in total.
HannahMontana
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It's snowing at Randolph Air Force Base in the Schertz area, which is a NE suburb of SA.
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