TX Winter Wx Threat # 9--- Another Arctic Outbreak?

[KatDaddy]

San Antonio-Austin AFD excerpt:

PRECIP WILL STAY IN THE FORECAST THROUGH
THURSDAY AS THE SOUTHERN BRANCH REMAINS ACTIVE. BY LATE NEXT WEEK...A
VERY COLD PATTERNS SETS-UP WITH GOOD POLAR TRANSPORT ALLOWING AN
ARCTIC AIRMASS TO MOVE SOUTH TOWARD OUR AREA.

[wxman57]

That's the coldest run(0z) at 500mb that I have seen from that model(GFS) the past couple days. I would disregard the temperature output as it doesn't match the upper level flow. It's just having trouble with surface features because of the extreme cold. If that pattern verifies next weekend, then Texas will be in the deep freeze from Friday through Monday, maybe even longer. Also, on Thursday, look for a surprise snow event for the northern parts of the state.

Glad to see people are catching in. Good post. Time to head to work. I think a speacial weather statement is in order for our clients today.

[pwrdog]

feb-26 Morning updates Houston, Dallas and Oklahoma City...

Houston-FD

CONFIDENCE AFTER TUESDAY IS LOW AS THE ECMWF
SHIFTS MUCH OF THE MOISTURE NORTHEAST OF THE REGION. ALSO THE
500 MB ECMWF SHOWS A LARGE RIDGE OVER ALASKA AND A DEEP TROUGH
OVER THE EASTERN 2/3RDS OF THE U.S. THIS WOULD SUGGEST
CONSIDERABLY COLDER TEMPERATURES FOR THE END OF NEXT WEEK. FOR NOW
LEANED TOWARD MEX GUIDANCE BUT THINK FUTURE MODEL RUNS WILL TREND
COLDER TOWARD THE END OF NEXT WEEK. UKMET AND CAN SUPPORT THE
COLDER ECMWF PATTERN. 43

Dallas-FD

AN ARCTIC COLD FRONT WILL
PUSH INTO THE SOUTHERN PLAINS THURSDAY MORNING. IT APPEARS THE
BULK OF THE COLD AIR WILL STAY JUST TO OUR NORTH. NONETHELESS...
CHILLY TEMPERATURES ARE IN STORE FOR NORTH TEXAS TOWARDS THE END
OF NEXT WEEK. /13

Ok City-FD

UPDATE...
CONCERN IS INCREASING OVER THE POTENTIAL FOR ACCUMULATING SNOW
NEXT WEEK. 06Z GFS LOOKS MUCH MORE LIKE THE 00Z ECMWF AND DEPICTS
A BROAD LONGWAVE TROF SETTING UP WITH AN AXIS FROM A LOW OVER
HUDSON BAY SW ACROSS N PLAINS INTO THE SW STATES. AMPLIFIED
UPSTREAM RIDGE CONTINUES NEAR 130-135W AND THE HIGHLY MERIDIONAL
FLOW IN BETWEEN WILL CONTINUE TO SEND FREQUENT REINFORCEMENTS OF
COLD AIR SOUTHWARD. THIS LONGWAVE PATTERN IS VERY FAMILIAR - A
CLASSIC PATTERN B OR ARCTIC HEAVY SNOW PATTERN FOR OK. THIS ONE IS
NOTORIOUS FOR PRODUCING SNEAK SNOW EVENTS DUE TO THE DOMINANCE OF
THE LARGE-SCALE PATTERN AND THE RELATIVELY BENIGN OR EVEN NON-
DETECTABLE SMALLER-SCALE FEATURES. SNOW EVENTS TYPICALLY OCCUR
WITHIN ABOUT 12-24 HR AFTER COLD FRONT PASSAGE - OF WHICH THERE
WILL BE SEVERAL - AND MAY BE TIED TO MESOSCALE WARM ADVECTION...
SPEED MAX DYNAMICS... OR FRONTOGENETIC FORCING. 06Z GFS MAY WELL
BE OVERDONE ON RUN-TOTAL SNOWFALL... BUT FACT THAT MUCH OF THE CWA
IS UNDER 6-14 INCHES BY NEXT FRIDAY IS WORTH NOTING. ANALOG CASE
THAT COMES TO MIND IS JAN-FEB 1985... DURING WHICH SEVERAL SNOW
EVENTS PILED UP TO MORE THAN A FOOT ACROSS EVEN S-SE OK.

It looks like more are starting to bite..

[A1A]

What gives? The 10 day forecast from the Weather Channel for central Texas is showing no cold blast (thru Sun, Feb. 4). Is it possible the front stays north??

[Air Force Met]

What gives? The 10 day forecast from the Weather Channel for central Texas is showing no cold blast (thru Sun, Feb. 4). Is it possible the front stays north??

Have we not learned the lesson yet about how poorly the GFS (especially) handles arctic air? Don't look at the sfc charts...except for general interest...but certainly not to make any kind of temp forecast off of...it will be wrong.

Look guys...for the time being...and probably until mid week of next week...you can throw out what you see on the sfc runs. We have seen it over and over again...don't fall into the same trap AGAIN that the NWS is falling into AGAIN.

I mean..."IT APPEARS THE BULK OF THE COLD AIR WILL STAY JUST TO OUR NORTH. "

Sure...that is what the model is saying...and the coldest air will stay north (it's always colder up north!)...but given the forecasted pattern...do you honestly think the arctic (dense...cold) air will stay north?

Will these people never learn? I mean...we get arctic air when the flow is SW aloft from the Dakotas all the way to the Gulf (1989...for instance)...what's going to happen when the pattern is a straight shot all the way from Santa's worskshp?

It really bothers me when met's make statements like this because the models say so....and they don't use any "thought" at all.

Since when has arctic air stayed north when the flow is all the way to the Rio Grande? Heck...arctic air doesn't stay north when the flow is zonal over the whole US.

Here is the 500mb from Feb 1989 (very zonal...but the high over AK to dislodge the arctic dome)...and the 1000mb...note the zonal flow all the way from Canada to the Gulf.

http://vortex.plymouth.edu/cgi-bin/gen_ ... e=1024x768


http://vortex.plymouth.edu/cgi-bin/gen_ ... e=1024x768

[Air Force Met]

What gives? The 10 day forecast from the Weather Channel for central Texas is showing no cold blast (thru Sun, Feb. 4). Is it possible the front stays north??

Oh...and what gives is they are using the GFS for that forecast and the GFS stinks in these situations. You have to actually 1) have a Met who knows what the pattern will do and what it is capable off...and who will stay away from the model output for the sfc and 2) Make an actual forecast...not something computer generated.

[ETXHAMXYL]

Talked to my brother-in-law up in HOmer Alaska last night. He asked me how's the weather down there? I said mild after some cold last week. He said well I bet you next week you will be in the deep freeze again. I said why? He said right now it is white out and temps dropping fast. He lives on the coast where it isn't as cold or snowy as the other parts of alaska. He said that usually after they get a big cold spell we get it the following week.

So maybe he is right about us down here next week. He was right about it last week.

[cctxhurricanewatcher]

What gives? The 10 day forecast from the Weather Channel for central Texas is showing no cold blast (thru Sun, Feb. 4). Is it possible the front stays north??

Have we not learned the lesson yet about how poorly the GFS (especially) handles arctic air? Don't look at the sfc charts...except for general interest...but certainly not to make any kind of temp forecast off of...it will be wrong.

Look guys...for the time being...and probably until mid week of next week...you can throw out what you see on the sfc runs. We have seen it over and over again...don't fall into the same trap AGAIN that the NWS is falling into AGAIN.

I mean..."IT APPEARS THE BULK OF THE COLD AIR WILL STAY JUST TO OUR NORTH. "

Sure...that is what the model is saying...and the coldest air will stay north (it's always colder up north!)...but given the forecasted pattern...do you honestly think the arctic (dense...cold) air will stay north?

Will these people never learn? I mean...we get arctic air when the flow is SW aloft from the Dakotas all the way to the Gulf (1989...for instance)...what's going to happen when the pattern is a straight shot all the way from Santa's worskshp?

It really bothers me when met's make statements like this because the models say so....and they don't use any "thought" at all.

Since when has arctic air stayed north when the flow is all the way to the Rio Grande? Heck...arctic air doesn't stay north when the flow is zonal over the whole US.

Here is the 500mb from Feb 1989 (very zonal...but the high over AK to dislodge the arctic dome)...and the 1000mb...note the zonal flow all the way from Canada to the Gulf.

http://vortex.plymouth.edu/cgi-bin/gen_ ... e=1024x768


http://vortex.plymouth.edu/cgi-bin/gen_ ... e=1024x768

Ding, ding, ding. We have a winner. This needs to be archived and posted everytime we note the worship of the GFS by some of our NWS offices in Texas and the south and likewise TV forecasters.

[Portastorm]

What gives? The 10 day forecast from the Weather Channel for central Texas is showing no cold blast (thru Sun, Feb. 4). Is it possible the front stays north??

It has been said many times ... but I'll say it again ... you need to know that those Weather Channel forecasts are generated from a computer model run of the GFS. There are merely guidance numbers and should not be taken seriously beyond 48 hours. There is no human element of forecasting involved with those numbers whatsoever. So really ... don't pay much attention to them beyond the forecast they show for your area for today or maybe tomorrow.

Listen to the pro mets on this board and some of the pro mets that posters reference from other sources. Any post from wall_cloud, AirForceMet, Wxman57, or Jeff are worth paying close attention to as these guys are professional meteorologists who not only use computer guidance but their own experience and we're fortunate that they share it with us weather weenies.

Bottom line: the Arctic air is coming next week. Get ready or get caught.

[aggiecutter]

The 0z EURO is putting the core of the cold farther west, which is good news. It also has a SW flow a loft over the cold air while it is in place over Texas. It also brings back the SE Ridge, which would be the recipe for a storm to track from the GOM up the Mississippi and Tennessee valley. If you want winter precip and not just cold, this is the run you would want to come to fruition.

0Z EURO: You can change the parameters as needed:
http://www.ecmwf.int/products/forecasts ... uv850_z500

[Air Force Met]

The 0z EURO is putting the core of the cold farther west, which is good news. It also has a SW flow a loft over the cold air while it is in place over Texas. It also brings back the SE Ridge, which would be the recipe for a storm to track from the GOM up the Mississippi and Tennessee valley. If you want winter precip and not just cold, this is the run you would want to come to fruition.

0Z EURO: You can change the parameters as needed:
http://www.ecmwf.int/products/forecasts ... uv850_z500

Wow. That is a recipe for BRRRRR. -22C at 850mb...which means a lot colder at the sfc (arctic air has that inversion thing going...). That pattern will send it southwards and it will stop at the Yucatan...maybe.

[gboudx]

I mean..."IT APPEARS THE BULK OF THE COLD AIR WILL STAY JUST TO OUR NORTH. "

I'm somewhat surprised by the DFW offices comment this morning as well. I won't believe that they didn't learn anything from the events of earlier this month, when the cold air defied the models and came through. Are they just showing restraint in the public forecasts, but privately know this could be worse? But even if that were the case, why mention the "bulkd of the cold air will stay just to our north"? I know there's no answer for this. Maybe I'll tune in and see what your former classmate has to say.

[Air Force Met]

I mean..."IT APPEARS THE BULK OF THE COLD AIR WILL STAY JUST TO OUR NORTH. "

I'm somewhat surprised by the DFW offices comment this morning as well. I won't believe that they didn't learn anything from the events of earlier this month, when the cold air defied the models and came through. Are they just showing restraint in the public forecasts, but privately know this could be worse? But even if that were the case, why mention the "bulkd of the cold air will stay just to our north"? I know there's no answer for this. Maybe I'll tune in and see what your former classmate has to say.

Yeah...maybe she'll catch on. We were both there for the arctic outbreak of Feb 1989...so maybe the lesson is still embedded in that pretty little head of hers.

Of course...that was a 1078.5 mb high (31.85 inches)...not a whole lot was stopping that thing...didn't matter what the pattern was. Set the lowest pressure (at the time) in Gilbert...then the highest just a few months later. It was a great time to be a met student.

[cajungal]

I was 13 years old in 1989. We hovered around 13 degrees here and got around an inch and half of snow that actually stuck for 2 days. It has been so long that I can't imagine what that cold feels like anymore. When you are a kid, you don't even feel it like you do when you are an adult. I don't think we have even seen the teens here in over 15 years. I do think it will be bitterly cold for the gulf coast. Exactly how cold? That is the question we can't exactly pinpoint right now this far out.

[gboudx]

I was 13 years old in 1989. We hovered around 13 degrees here and got around an inch and half of snow that actually stuck for 2 days. It has been so long that I can't imagine what that cold feels like anymore. When you are a kid, you don't even feel it like you do when you are an adult. I don't think we have even seen the teens here in over 15 years. I do think it will be bitterly cold for the gulf coast. Exactly how cold? That is the question we can't exactly pinpoint right now this far out.

I was 18 back then. I was running an errand for work at the time the front came through. My drive home was normally about 15 mins, but it took me 3 hours that day. For us cajuns, sno is something we put in cups during the summer and pour colored syrup over.

[Air Force Met]

I was 18 back then. I was running an errand for work at the time the front came through. My drive home was normally about 15 mins, but it took me 3 hours that day. For us cajuns, sno is something we put in cups during the summer and pour colored syrup over.

That was one of the sharpest drops in temp I can ever remember for a front. We were at the O&M building on campus on the 2nd of Feb. waiting for it to come through. It was in the evening. It was in the middle 70's and I was in shorts. My dorm room was on the north side of campus (the O&M building is on the east side). We watched it come through Waco...and we decided to leave and get back to our dorms before it hit. We waited too long. As I walked out the rotating doors and got about 100 yards away...it hit. It went from about 73 to about 45 instantly. Then it was a steady drop after that. By midnight it was 38...and by the next morning it was in the 20's...and it stayed there until the 7th when it got to about 38 or so.

For those who know the campus (old campus at least), that was when Mt Aggie was there....where the "Snow Ski" class was offered. We "borrowed" trays out of Sabisa dining hall and used them to sled down Mt Aggie...then we took them to the Rainbow (the bridge over Welbourn road) and sledded down that. Campus was closed for a couple of days because of the ice. Lots of fun.

[jeff]

Rain returns tonight into Saturday.

Upper pattern looking very favorable for extensive cold air outbreak.

Discussion:

Mexican upper low starting to open and slide NE toward TX. Sub-tropical jet is starting to pull into position to begin its wet assault with favorable upper air support. Coastal low formation will be rapid overnight with extensive moistening of the low levels with clouds rapidly increasing and lowering. Cold dome will remain entrenched at the surface however surface coastal boundary may attempt to penetrate the coastal zones Saturday AM. Will keep most of the area in the cool sector with strong isentropic lift overhead resulting in widespread rainfall. Elevated instability increases and thunderstorms become the result by early Saturday morning. Feel the best chances will be from around sunrise through early afternoon splitting the timing differences offered by the GFS and NAM.

Strong front blasts through Sunday behind the departing system with decent cold air advection…however this is likely just a taste of what is to come over the next 2 weeks. Highs may struggle through the 50’s on Sunday and Monday as Canadian high pressure builds into the region. NW upper flow transitions back to SW with our friend the sub-tropical jet appearing again by Tuesday into Wednesday. Uncertainty is high during this period as the Pacific flow overrides the cold dome at the surface resulting in at least clouds and maybe rain.

Extended:

Extremely amplified upper air pattern develops with massive ridging building deep into Alaska an into N Russia with deep downstream troughing over the central and eastern US. Pattern is a classic textbook arctic air outbreak event! Will toss the GFS out the window as lessons with this model and arctic air mass handling have been clearly proven this winter. Support of the 500 to 300mb pattern is strong among the numerous models even though the GFS keeps the surface cold bottled up over the central plains….arctic air does not stop due to unfavorable upper air flow. Will disregard the GFS temp. output and go many degrees colder starting next Friday. May need to speed first arctic front up by 12-24 hours as model timing with such events is usually too slow. Cold Siberian air mass with cross polar flow all the way to TX is supportive of bitterly cold temps. Upper air pattern is similar to that of the Dec 1989 and 1983 outbreaks…however Siberian air mass is not extraordinarily cold at the moment.

Undercutting sub-tropical flow will remain and feel the dense and very cold arctic air will bleed under the SW flow aloft. Potential will be in place by next weekend for winter storm conditions once again across TX and the southern plains/southern US. Close watch is needed on this potential cold air outbreak.

[icicle]

Jeff: thanx, that sounds like "the day after tomorrow'' type weather . my local NWS offices here have been hinting at the artic outbreak with terms like "possible", and ''maybe''. i'm not sure how cold it will get here, but it will prolly be the coldest we have seen in ages.

[richtrav]

I was 13 years old in 1989. We hovered around 13 degrees here

Sure you're not confusing Feb '89 with Dec '89?

[Air Force Met]

I was 13 years old in 1989. We hovered around 13 degrees here

Sure you're not confusing Feb '89 with Dec '89?

Dec 89 was a lot colder for LA than Feb 89 was...LaFayette got down to 8 or something like that.