The Official Texas Snow Thread...

[aggiecutter]

You folks in North Texas need to keep an eye on the saturday-sunday time-frame. The rain-snow line and the moisture are real close. If the model is off just a little, and I've seen this happen several times before, then Northern and NE Texas could be in for a pretty good snow event. Uphere in Texarkana, we've gotten 8" of snow on two different occasions over the past 7 years when the models didn't get good handle on the cold air and moisture. The models were either wrong on the amount of cold and moisture, or both.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _054.shtml

[Air Force Met]

Air Force Met, are you trying to say that JB is prone to a little hyperbole.

Not sure that's the right word....but he tends to fly his plane into the ground instead of ejecting at a safe altitude...which is what a good forecaster does. That's -removed-. He's a good forecaster...but he's missing greatness because he's too prone to holding on...and his detractors remember it rather than remember his many successes.

People need to remember that changing forecasts is not flip-flopping...it's forecasting. When you do it with every change of the model...then that's flip-flopping...but changing it when you see reasons to do so is good meteorology.

[Johnny]

I checked out the temperatures in different towns in Nunavut, Canada. This looks to be where the cold air will be coming from. As of today, high temperatures have peaked across the territory of Nunavut. Current readings show.....

Eureka -38

Gjoa Haven -31

Shepard Bay -29

Robertson Lake -29



By Monday of next week the high temperatures for the same above places will be....

Eureka -11
Gjoa Haven -5

Shepard Bay -5

Robertson Lake 0


As you see temperatures will warm during this time period so my only guess is that cold air will be dislodged and push southward. I also checked the extended temperatures across Saskatchewan and Manitoba and there temperatures drop starting tomorrow and into Monday but only by about 10 to 12 degrees area wide. Ontario temperatures seem to stay the same through Monday and so do Alberta's so the bulk of the cold air will slide straight down into Saskatchewan and Manitoba and then into the CONUS.

[Air Force Met]

Usually when very cold arctic air settles into Texas, it comes from Alaska. I'm guessing both in 1983 and in 1989 the cold air came out of Alaska and not northern Canada? As of now Alaska's temperatures are not that cold at all. The region that is holding the very cold air is in the northern region of Canada where temperatures are running anywhere from -17 to -38. It's a given that this is where JB is getting his cold bias from but doesn't bitter cold air in northern Canada usually veer off to the east once it enters the CONUS? Have we ever had a strong arctic front push through the entire state of Texas where the cold air came from northern Canada where the bitterly cold temperatures currently are?

You are correct. That's the main reason I had a hard time with the 1989 comparison...AK isn't that cold right now...neither is Canada. Alaska is OUR source region for Arctic events. We get polar fronts with a Canadian source region all the time but those event sthat put us into the teens with 20's for highs always come from Alaska...sliding down the lee side of the Rockies. Ine instances...'83 and '89...the ridges at the sfc are massive and can be reinforced from SIberia and that keeps us in the deep freeze for a while.

And yes...the cold air...if it's only in northern Canada...usually goes east. Reason being this: Cold air advection lowers upper level heights. That means the polar vortex is likely to be more to the east...so the flow over the northern US is more out of the west or northwest...rather than plunging southward. That takes the air eastward. That's another reason I was having a hard time with the cold air coming this way...as I said...the upper air patter was favorable for it to go east. Even though the models were sending it south at the time (go back a few threads). The cold air was over Canada...that should lower heights over the northern US and thus send more of the flow eastward ratehr than southward.

As far as your alst question. It's happened. I'm not a big study of every cold snap...just ones in my lifetime. The 1979 outbreak in January (1-3) was kinda a combo. Some of the source was from northern Canada and some from AK. The January 1982 event started in the N Canada/AK source region and moved around from central Canada to AK for days (almost 2 weeks) before finally coming down due to the Polar vortex being over that part and zonal flow...then a ridge built up and knocked it out when it was located on the east side of the Canadian rockies.

So it can happen...but what seems to be the trigger is a stagnant pattern for a while then the ridge builds. You need the vortex to move far to the south and send it south from that source region...or you need it to weaken altogether...almost into nothing (like it did in '82) and then the flow to become NNWerly down the rockies. However, in order to get a good shot...you need to see temps near -30F - -40F near Montana with that air.

[Portastorm]

Looks like the Fort Worth NWSFO is now bullish on a frozen precip event next week for at least part of its CWA. See below from its afternoon discussion:

THE WESTERN RIDGE EXTENDS FAR INTO THE YUKON TERRITORY BY THIS
WEEKEND...THUS FORMING A MCFARLAND PATTERN. THIS SHOULD TRANSPORT
ANOTHER SLUG OF ARCTIC AIR SOUTHWARD INTO THE SOUTHERN PLAINS FIRST
OF NEXT WEEK WITH A REINFORCING SHORT NEXT WEDNESDAY NIGHT. THERE
WILL ALSO BE A CHANCE OF A WINTRY PRECIPITATION MONDAY NIGHT THROUGH
TUESDAY AS ANOTHER UPPER LOW UNDERCUTS THE WEST RIDGE AND MOVES
ACROSS TEXAS. BEST LIFT WILL BE OVER THE SOUTHERN CWA...WHICH IS
CLOSER TO A STRONG BAROCLINIC ZONE ALONG THE TEXAS COAST. THUS
PRECIPITATION AMOUNTS WILL BE LIGHT OVER THE NORTHERN TWO-THIRDS AND
UP TO 1/3 INCH OVER THE SOUTHERN COUNTIES. FORECAST SOUNDINGS FAVOR
A WET SNOW OVER THE SOUTHERN ONE QUARTER TUESDAY AND BASICALLY LIGHT
SNOW OVER THE REST OF THE CWA.

[jkt21787]

Not to rain on your parade, but you did leave this part out which gives an indication they think its not a huge deal...

RIGHT NOW...WE DO NOT FORESEE SIGNIFICANT SNOWFALL OR MAJOR TRAVEL PROBLEMS DOWN SOUTH NEXT TUESDAY

[Stratosphere747]

AFM- Always thought your explanations of tropical entities were top notch, but your winter knowledge and reasoning is equal.

Still get a chuckle on some of the arguments that went on in the Tropical forum.

Scott

[Portastorm]

Not to rain on your parade, but you did leave this part out which gives an indication they think its not a huge deal...

RIGHT NOW...WE DO NOT FORESEE SIGNIFICANT SNOWFALL OR MAJOR TRAVEL PROBLEMS DOWN SOUTH NEXT TUESDAY

Details, details.

Never underestimate the value of a good copy editor .. or a good researcher for that matter! Point taken.

[jkt21787]

Not to rain on your parade, but you did leave this part out which gives an indication they think its not a huge deal...

RIGHT NOW...WE DO NOT FORESEE SIGNIFICANT SNOWFALL OR MAJOR TRAVEL PROBLEMS DOWN SOUTH NEXT TUESDAY

Details, details.

Never underestimate the value of a good copy editor .. or a good researcher for that matter! Point taken.

DFW definitely making a point in their ZFP thats its not a big deal at least for the metroplex...

TUESDAY MOSTLY CLOUDY WITH A 20 PERCENT CHANCE OF VERY LIGHT SNOW. HIGHS IN THE MID 40S.

Don't see "very" added to the zone forecast often at all.

[Extremeweatherguy]

It doesn't matter if there are travel problems. Any snow is good...even if it is nice and light. If it plays out then may be i'll have to take a drive towards Waco on Tuesday.

Waco's Forecast:

Tuesday: A chance of rain and snow. Mostly cloudy, with a high around 44. Chance of precipitation is 30%.

Tuesday Night: A 20 percent chance of snow. Cloudy, with a low around 29.[/b]

[cctxhurricanewatcher]

I'm confused as heck now about what's going on. The way it looks now from all of the talk and analysis, we might be head for record highs and a week of wearing shorts and Hawaiian shirts before Christmas.

Just give me cool to cold weather with that winter overcast and I'll be happy.

[gboudx]

How can the San Angelo NWS put out an SPS for their CWA regarding the wintry precip event next week, while DFW is so ho-hum about it? Is it possible the worst of this event will affect the area just to the west of DFW?

[jkt21787]

How can the San Angelo NWS put out an SPS for their CWA regarding the wintry precip event next week, while DFW is so ho-hum about it? Is it possible the worst of this event will affect the area just to the west of DFW?

Yes. This system will be supressed due to the very strong high pressure, limiting moisture the further north you are. The San Angelo area will have better moisture to work with, plus the cold air too, so they have better chances overall.

Add to that that the dynamics will be moving more southeast rather than east, so the further east you go too, the less chances are.

[southerngale]

Well, donkey butts!

I was away from my computer all morning and didn't get to check in, then heard the local news at noon, and he was definitely hinting at snow here either Tuesday or Wednesday next week. It gave me the impression our chances were increasing, not decreasing.

[jkt21787]

Well, donkey butts!

I was away from my computer all morning and didn't get to check in, then heard the local news at noon, and he was definitely hinting at snow here either Tuesday or Wednesday next week. It gave me the impression our chances were increasing, not decreasing.

Well you will still have good moisture around in your area, downside is that you will be a good bit warmer, so all rain for you. I believe HGX was saying this afternoon that far NW counties still had a slight chance for some wintry too.

[jeff]

Quite the event yesterday with a couple of tornadoes and way too much rain in a short period of time. IAH set a daily rainfall record of 5.64 inches.

2 tornado touchdowns were along Hwy 99 South of I-10 and also near Crosby. The Crosby cell did produce minor damage.


Next rain event shaping up for Saturday as active southern stream flow remains in place. So. Ca storm system will eject into TX late Friday inducing coastal troughing and surface low pressure over the western Gulf. Strong isentrophic lift will begin late Friday evening and continue into Saturday with surface low pressure pulling up the coast. Widespread 1.0-1.5 inches is likely. Given the now saturated soil conditions some flooding may develop, although this event looks to be more of a widespread light to moderate rain over several hours which we should be able to handle. Should the low form or move closer to the coast bringing the warm sector onshore, the severe and flood threat will increase. Anything should be liquid, but it will be quite chilly during the day Saturday with gusty NE surface winds and temps. in the 40’s. This will be looked at much closer tomorrow with respect to the heavy rainfall and any severe threat.


Extended:

Cold arctic air mass still progged to arrive early next week. Feel the GFS is still out to lunch with respect to temperatures and I will knock off about 10 degrees for the day time highs. Progged profiles suggest snow for our northern counties Tuesday through Wednesday roughly along and north of a College Station to Livingston line. Typical model bias with cold arctic air masses is to be warmer than what actually happens, however delaying of the arrival of the cold air as has been the case is also a sign against the typical warm bias. Considering we are talking snow (which is like saying hurricane around these parts) and we are talking well into next week I will await additional guidance and watch trends before getting overly excited about the possibilities. Feeling right now is that profiles across the metro area will remain too warm for anything, but much can and will likely change between now and next Tuesday which could promote a greater winter weather threat for a larger part of our area.

[gboudx]

How can the San Angelo NWS put out an SPS for their CWA regarding the wintry precip event next week, while DFW is so ho-hum about it? Is it possible the worst of this event will affect the area just to the west of DFW?

Yes. This system will be supressed due to the very strong high pressure, limiting moisture the further north you are. The San Angelo area will have better moisture to work with, plus the cold air too, so they have better chances overall.

Add to that that the dynamics will be moving more southeast rather than east, so the further east you go too, the less chances are.

What was confusing me is that their SPS seems to cover their entire CWA, which extends, in latitude, further north than Ft. Worth, Dallas, and where I live. I guess they are applying some CYA to cover the whole CWA.

[Air Force Met]

How can the San Angelo NWS put out an SPS for their CWA regarding the wintry precip event next week, while DFW is so ho-hum about it? Is it possible the worst of this event will affect the area just to the west of DFW?

Read my analysis of the low that is moving over them The 00Z run had a shortwave zooming through the state. The 12Z now sits a 500MB low over them...but that warm layer might wreck them too.

[southerngale]

Well, donkey butts!

I was away from my computer all morning and didn't get to check in, then heard the local news at noon, and he was definitely hinting at snow here either Tuesday or Wednesday next week. It gave me the impression our chances were increasing, not decreasing.

Well you will still have good moisture around in your area, downside is that you will be a good bit warmer, so all rain for you. I believe HGX was saying this afternoon that far NW counties still had a slight chance for some wintry too.

Yeah, I'm not in a far NW county. But, one thing is almost certain: whatever is predicted at this moment for days 5 and 6 won't be exactly the way it happens so maybe things will change for the snowy better.

Of course, I'm not holding my breath, but I will keep my Snow Train ticket handy, just in case.

[Air Force Met]

This is weird. The accuweather.com forecast for Spring, Texas now calls for 42 next Tuesday with rain and then 34 next Tuesday night with a mix of rain and snow. Now I am not saying that I am going to start yelling "snow!" again...but this is a pretty cool forecast for being just 5 days out. Now only if it were to verify... ahhh that would be nice.

One thing these other forecasters need to remember about forecasting snow down here is: because of our prximity to the Gulf, we are much more likley to have a warm layer aloft which will melt the snow before it reaches the ground. A low of 34 with a warm layer aloft will...MAY give you some sleet but most times it won't give you any snow unless you are above freezing 500'-1000' AGL. If you've got a warm layer, you aren't getting snow. Forecasters in other parts of the country fail to remember these things because they get snow all the time when it's 35-36 degrees...so why shouldn't Houston? We are much more likley to have a warm layer aloft to melt the snow here than they are in State College when the temp is 34F. That's why they get snow at 34F sometimes and we get cold rain with some sleet if we're lucky.