Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 6

[Srain]

What is your gut telling you Steve?  FWD just barely touched on the New Years forecast this morning:

 

THE GFS AND ECMWF SOLUTIONS DIFFER

ON HOW COLD IT WILL GET BY THE MIDDLE OF NEXT WEEK AS ANOTHER

TROUGH MOVES INTO THE WESTERN U.S. AND COLD AIR IN THE LOWER

LEVELS WORKS ITS WAY DOWN THE PLAINS. HAVE USED A BLEND OF THE

ECMWF AND GFS MODELS...BUT SOME VERY COLD AIR IS POSSIBLE FOR THE

END 2014 AND BEGINNING 2015.

 

Hopefully, we can get Cavanaugh on a slow night here soon and he will write up one of his epic discussions.

I have little doubt the cold air is coming. What we cannot determine beyond 3-5 days are these pesky upper air disturbances and if a Coastal low/wave develops later next week when the cold air is entrenched across our Region. The 00Z Euro suggested anywhere for 1-3 inches of snow here in Houston with 3-6 in Lufkin and 2 inches in Beaumont. If a Coastal low develops, that tends to be a dry and cold pattern for you folks in N Texas as all the moisture is further S. Let's see what the weekend brings, but I do believe the cold air is not an issue.

[Quixotic1]

1050 highs kinda barrel on through. Much like last year's pattern. Course, it could fall right like December 6 last year. Right now my money would be south.

[vwgrrc]

1050 highs kinda barrel on through. Much like last year's pattern. Course, it could fall right like December 6 last year. Right now my money would be south.

Oh~ I do miss Dec 6 2013. But that pattern was so rare. Everything come together perfectly for N TX.

 

If I remember correctly, that event was confirmed almost 5 days in ahead! Let's see how this time develops

[DFWWeather]

Oh~ I do miss Dec 6 2013. But that pattern was so rare. Everything come together perfectly for N TX.

 

If I remember correctly, that event was confirmed almost 5 days in ahead! Let's see how this time develops

 

Classic setup for an ice storm across North Texas. Similar conditions in the February 24, 2003 event too. Also, even better setup in early February 1989 when we had thunderstorms of sleet come down so hard it came in huge blocks of ice. January 1988 was also a pretty good setup too. All events listed, ice accretions on area roadways was more than 1 to 2 inches thick. The February 1989 had ice on the ground for a solid week with schools closed the entire week.

[Portastorm]

12z Euro run looks sweet on a major Texas winter storm event for New Years Eve/New Years Day. If it verifies, I only hope we can get Frankie Macdonald to do a special video update for us!

[ams30721us]

From AFD from ShV:

 

 

BIG CHANGES COMING TO THE REGION FOR THE LAST WEEK OF 2014 IN THE
FORM OF MUCH COLDER AIR AND PERHAPS SOME WINTER PRECIPITATION.
DEEP UPPER TROUGH DIGS INTO THE INTER MOUNTAIN WEST ON MONDAY
BEFORE CLOSING OFF AND DIGGING INTO THE FOUR CORNERS REGION FOR
TUE. THIS WILL KEEP US UNDER STRONG SOUTHWESTERLY FLOW ALOFT WHICH
WILL RESULT IN CONTINUED RAIN CHANCES TUESDAY/TUESDAY NIGHT. THE
LEADING EDGE OF A MUCH COLDER...POLAR AIRMASS WILL BE MOVING INTO
OUR REGION LATE TUESDAY INTO TUE NIGHT AS WELL. THICKNESS AND MODEL
FCST SOUNDINGS SUGGEST A CHANGE OVER FROM RAIN TO SNOW TUE NIGHT
ACROSS OUR NORTHERN THIRD WITH A RAIN SNOW MIXTURE WEDNESDAY AGAIN
ACROSS OUR NORTHERN ZONES. MORE OF THE AREA COULD GET IN ON SOME
WINTER PRECIPITATION FOR NEW YEARS DAY...ESPECIALLY IF THE ECMWF
MODEL SOLUTION COMES TO FRUITION BUT NEEDLESS TO SAY...THIS
REMAINS A LONG WAY OUT INTO THE EXTENDED PORTION OF THE FORECAST.
OBVIOUSLY...THIS SYSTEM WILL CONTINUE TO BE MONITORED CLOSELY.
THERE IS ONE THING THE MEDIUM RANGE PROGS DO AGREE WITH HOWEVER...
AND THAT IS THAT A MUCH COLDER AIRMASS WILL BE ARRIVING INTO THE
FOUR STATE REGION NEXT WEEK.

 

[Portastorm]

Afternoon AFD from EWX had some interesting thoughts about next week. 

 

Relevant snippet:

NOW FOR THE MOST INTERESTING PART OF THE FORECAST. AS THIS TROUGHMOVES OUT SUNDAY...THE NEXT STORM SYSTEM WILL BE TAKING SHAPEACROSS THE NORTHWEST CONUS SUNDAY EVENING. A VERY AMPLIFIED RIDGEAXIS WILL BE EXTENDED OFF THE WESTERN CONUS...NORTH INTO THECANADA/ALASKA BORDER WITH 500 HEIGHTS NEAR 570DM REACHING 60 DEGREESNORTH. THIS IS A STANDARDIZED ANOMALY OF ABOUT ABOUT 3 STANDARDDEVIATIONS ABOVE NORMAL FOR THAT REGION. TO THE EAST OF THIS RIDGEAXIS A VERY DEEP TROUGH AXIS IS ABLE TO THEN DIG SOUTHWEST WITH THEMAIN RIDGE AXIS ORIENTED FROM NEAR NORTH DAKOTA BACK INTO ARIZONAMONDAY EVENING. THIS UPPER PATTERN IS TYPICALLY KNOWN FOR BRINGINGCOLD ARCTIC AIRMASSES INTO TEXAS. MODELS ARE FORECASTING THE SURFACEHIGH BEHIND THE ASSOCIATED COLD FRONT TO ENTER THE CONUS NEARMONTANA SUNDAY. SURFACE HIGHS WHICH ENTER IN THIS REGION ARE KNOWNTO BE FAVORABLE FOR THE COLDEST AIRMASSES FOR THE SOUTHERN PLAINS.THIS IS MOSTLY DUE TO COLD AIR DAMMING WHICH OCCURS AS THE COLDAIRMASS MOVES SOUTH ON THE LEE SIDE OF THE ROCKIES. AS THE HIGHCIRCULATION DROPS SOUTH...EAST WINDS ON THE SOUTHERN PERIPHERY GETBLOCKED BY THE TERRAIN AND THE COLD AIR IS ALLOWED TO POOL ANDCOLLECT AS THE HIGH MOVES SOUTH. THIS ALLOWS THE AIR TO BECOME MOREDENSE WHICH EQUATES TO COLDER AIR. IT WILL BE INTERESTING TO SEE HOWTHIS SYSTEM PLAYS OUT...BUT MODELS TEND TO BE TOO WARM WITHTEMPERATURES WITH THIS PATTERN BY THE TIME THE COLD AIR MAKES ITINTO TEXAS. ANOTHER INTERESTING PIECE TO THIS PUZZLE IS MODELS AREIN FAIRLY GOOD AGREEMENT THAT A PIECE OF THE TROUGH WILL MOVETHROUGH THE AREA SOMETIME NEXT WEEK AFTER THE COLD AIR MAKES IT.THERE ARE TIMING AND STRENGTH DISCREPANCIES BETWEEN THE MEDIUM-RANGEGUIDANCE AND THIS IS LIKELY TO BE THE CASE FOR THE NEXT SEVERALDAYS. HOWEVER...MODELS THEN DO AGREE ON ENOUGH MOISTURE FOR PRECIPWITH THE SYSTEM. THE QUESTION THEN TURNS TO HOW TO CONVEY THEPOSSIBILITY OF WINTER PRECIP IN THE OFFICIAL FORECAST FOR DAY 7. FORNOW...WILL MENTION A RAIN OR FREEZING RAIN MIX FOR THE HILL COUNTRYTUESDAY NIGHT. THIS IS A GOOD START BECAUSE THERE ARE SOME TIMINGAND STRENGTH DIFFERENCES WITH THE TROUGH AS IT MOVES THROUGH THEREGION. THERE IS THE POTENTIAL THAT THE AIR MASS WILL COLDER THANWHAT THE GFS IS SUGGESTING...SIMILAR TO THE ECMWF SOLUTION FORTEMPS. THIS BEARS WATCHING AS THE FORECAST IS LIKELY TO CHANGE ONEWAY OR THE OTHER AS THE NEXT WEEK PROGRESSES.

[bubba hotep]

FWD offers up their first thoughts:

 

THE WEEKEND WILL BE RATHER CHILLY WITH HIGHS IN THE UPPER 40S BOTH
DAYS AND ONLY A SLIGHT WARMUP ON MONDAY AS THE UPPER TROUGH PULLS
AWAY. MODEL GUIDANCE IS IN GOOD AGREEMENT WITH BRINGING A CHUNK OF
ARCTIC AIR SOUTHWARD EARLY NEXT WEEK. A 1050MB SURFACE HIGH BUILDS
INTO MONTANA BY LATE MONDAY WITH THE ARCTIC FRONT SPILLING
SOUTHWARD INTO NORTH TEXAS ON TUESDAY. TEMPERATURES WILL BE
SHARPLY COLDER WITH BRISK NORTH WINDS. THIS SYSTEM BEARS CLOSE
WATCHING AS IT COULD BE FAVORABLE FOR WINTRY PRECIPITATION ACROSS
NORTH TEXAS. WITH A STRONG UPPER TROUGH STILL TO THE WEST THROUGH
MID WEEK AND THE 850MB TROUGH AXIS CLOSE BY...THERE COULD BE GOOD
WARM MOIST ADVECTION INTO NORTH TEXAS ATOP A VERY COLD AIRMASS.
THIS IS USUALLY FAVORABLE FOR FREEZING RAIN. RIGHT NOW IT LOOKS
LIKE A DEEPER COLDER AIRMASS WILL MAKE IT THROUGH THE AREA. WITH
COLDER TEMPERATURES ALOFT...SOME SORT OF MIX OR TRANSITION TO
SLEET THEN SNOW APPEARS MORE LIKELY. WITH A DEEPER COLDER AIRMASS
IN PLACE...MOISTURE QUALITY BECOMES MORE OF AN ISSUE AS WELL. WILL
CONTINUE TO MONITOR THIS SYSTEM CLOSELY THROUGH THE WEEKEND AS IT
COULD MAKE A MESS OF THE NEW YEAR HOLIDAY.

DUNN

[Srain]

Christmas Eve briefing from Jeff:

 

Increasing potential for strong arctic intrusion next week with possible winter storm 12/31-1/2.

 

Cold advection continues today with NW winds and temperatures in the 50’s which will set the stage for a cold and clear night and mostly sunny and cool Christmas with lows in the 30’s and highs in the 60’s.

 

Rapid changes underway on Friday as moisture returns ahead of the next incoming Pacific system. Clouds will increase and moisture may be enough by afternoon to support a few showers. Next cold front crosses the area Saturday night with showers and thunderstorms likely and then a period of post frontal upglide and rain Saturday night into at least the first part of Sunday with cold conditions. Overall the upcoming weekend will cool to cold and wet.

 

Next week:

Much of the focus continues to be on the middle to end of next week as very cold air looks increasingly likely to head southward. Strong upper level jet stream amplification will begin late this week with deep layer ridging pushing deep into Alaska and as far as 60 degrees north with the formation of a formidable downstream trough over the western and central US. Models are coming into decent agreement on this pattern and a very cold air mass dislodging from NW Canada and dropping southward under a large 1050mb+ arctic high pressure cell into Montana. This is an extremely favorable pattern to deliver very cold air to TX as the air mass dams against the Rockies mountains and surges quickly southward. Model guidance is almost certainly under-estimating the amount of cold air and likely is too slow in its arrival. Looks like the arctic front will enter TX next Tuesday and roar southward and off the coast next Wednesday…could be slightly faster than that with some models showing a 1045-1050mb high dropping as far south as Colorado out of WY and 1035-1040mb pressures into NW TX. Temperatures will tumble behind the frontal passage with strong cold air advection. Will need to undercut guidance, but not sure how much at this point given potential clouds and linger post frontal precipitation. Not looking at anything record breaking, but possible for a period of sub freezing temperatures even for daytime highs during the latter part of next week and the first weekend of 2015.  

 

Forecast models continue to suggest a portion of the positive tilted trough hangs back over the SW US allowing period of moisture to upglide over the arctic dome and produce periods of precipitation. Model soundings are showing mainly rain and freezing rain profiles for SE TX around New Year’s Eve and Day….but given how poorly they handle such air masses they are likely too warm and too far NW with their freezing rain. Depending on the amount of moisture it looks like temperatures will be cold enough to support P-type concerns across a good portion of TX and SE TX and this is something that will have to be watched closely over the next few days as details begin to firm up on what sort of storm system we may be facing ejecting across in the cold air mass. Overall setup looks favorable for a winter storm across TX New Year’s Eve and Day.

 

[vwgrrc]

Classic setup for an ice storm across North Texas. Similar conditions in the February 24, 2003 event too. Also, even better setup in early February 1989 when we had thunderstorms of sleet come down so hard it came in huge blocks of ice. January 1988 was also a pretty good setup too. All events listed, ice accretions on area roadways was more than 1 to 2 inches thick. The February 1989 had ice on the ground for a solid week with schools closed the entire week.

Looks like this time the temp won't corporate very well. 1/2 it will be well above freezing!

[1900hurricane]

We'll see, models do have a tendency to under-do the cold air damming caused by the Rockies with ~1050 mb highs. Even without taking this into account though, solutions this far out are far from stable. With that being said, pattern recognition seems to point to a good chance for someone in the state seeing something of the wintry variety, and guidance seems to actually be fairly well clustered considering the range. At this point, I'm feeling pretty optimistic.

[DFWWeather]

Looks like this time the temp won't corporate very well. 1/2 it will be well above freezing!

I was referring to the December 5th and 6th 2013 event as being similar setup as those ice events I mentioned, not current setup, though February 1989 would be similar to forthcoming pattern.

 

Models are not seeing the low level discharge with the Arctic intrusion with next week's event. Likely what will happen is the surface freezing temp line will out run the 0°C line at H85 in a setup like this. Surface pressure on some models are showing 1035 mb in West Texas. That will keep DFW well below freezing for a few days. Whether moisture supply is there or gets shut off is another matter entirely.

[aggiegeog]

The models will pick back up on the cold as they are still showing a cold pattern. We will see how deep the cold is and how much moisture there will be as it gets closer.

New Mexico is looking very cold and snowy for the next week plus.

[aggiegeog]

Merry Christmas and hope y'all have a wonderful day.

[Srain]

Merry Christmas Everyone from my home to yours. I still do not see any significant changes via the overnight ensembles. We have a our first heavy frost of the season here in NW Harris County all the way to the ground. It appears the New Mexico into West Texas and possibly into the Panhandles of Texas and Oklahoma could see some heavy snow with a freezing rain/sleet potential Friday into early Saturday for the lower elevations. The Sangre de Christo Mountains as well as the high Plains of the Rio Grande rift of Southern Colorado/Northern New Mexico may be measuring snow by the feet before next week ends. That bodes well for my upcoming sojourn to the Taos/Angle Fire/Red River ski areas on the 12th of January.

 

 

 

[bubba hotep]

Merry Christmas all! 

[Quixotic1]

Merry Christmas all!

And to you and all the other sub-forum regulars.

[DFWWeather]

Merry Christmas all ....

 

Don't freeze in the below pattern ... brrr!

 

[vwgrrc]

Merry Christmas All

I have a might-be-stupid question just curious about... What kind of model does Wunderground or TWC relied on for their 10D forecast? For instance, Wunderground is now showing above freezing for Jan 1-2 in DFW while PGFS indicating a much colder period. I keep watching this for a couple days, they're actually upgrading the temperature for Jan 1-2 regardless what the model says. Are they reliable sources at this range?  

[jhamps10]

Cavanaugh with another one of his famous detailed reads from FWD:

 

TAKING A STEP BACK FROM LOCAL AREA WEATHER...ELSEWHERE ON
SUNDAY...A STRONG UPPER TROUGH IS EXPECTED TO DIG SOUTH ACROSS
WESTERN CANADA AND MOVE OVER THE NORTHERN CONUS ROCKIES. THIS IS
IN RESPONSE TO A VERY STRONG UPPER LEVEL RIDGE THAT ALL MODEL
GUIDANCE INDICATES WILL AMPLIFY OVER THE YUKON AND OVER THE
ALASKA/CANADIAN BORDER. CONFIDENCE IN THIS PATTERN VERIFYING IS
HIGH AT THIS TIME AS THE NAEFS AND ECMWF ENSEMBLE MEANS ALL
STRONGLY POINT TO THIS SOLUTION. THE UPPER TROUGH APPEARS TO BE
STRONG...AND WAS LOCATED SOUTH OF DUTCH HARBOR ALASKA EARLY THIS
AFTERNOON PER WATER VAPOR SATELLITE IMAGERY.

ASSUMING THIS STRONG UPPER TROUGH MOVES OVER THE YUKON...AND THEN
DIVES SOUTH AS UPPER RIDGING AMPLIFIES THIS WEEKEND...THIS APPEARS
TO BE A VERY FAVORABLE LARGE SCALE UPPER AIR PATTERN THAT WILL
RESULT IN AN ARCTIC OUTBREAK FOR THE SOUTHERN PLAINS NEXT WEEK.
THE CONSENSUS OF 12Z MODEL GUIDANCE CERTAINLY SEEMS TO SUPPORT
THIS SOLUTION...SO THINK THAT THE POTENTIAL FOR ARCTIC AIR TO
BUILD ACROSS THE SOUTHERN PLAINS ON TUESDAY IS VERY HIGH AT THIS
TIME. THE STRENGTH OF THIS ARCTIC AIRMASS...ONCE IN PLACE...WILL
HAVE A LARGE IMPACT ON THE FORECAST FOR NEW YEAR`S EVE AND DAY AS
PRECIPITATION IS EXPECTED TO BEGIN TO BUILD OVER THE REGION ABOUT
24 HOURS AFTER THIS ARCTIC AIR IS IN PLACE.

MODELS SEND A SHALLOW ARCTIC AIRMASS SOUTH ALONG THE HIGH PLAINS
RAPIDLY MONDAY NIGHT INTO TUESDAY MORNING. THIS AIRMASS IS THEN
EXPECTED TO BUILD A BIT SLOWER TO THE EAST...ALMOST SPREADING
ITSELF FROM WEST TO EAST ACROSS THE CWA INSTEAD OF RUSHING IN
BEHIND A WELL DEFINED FRONTAL BOUNDARY. MODELS INDICATE THAT THIS
AIRMASS WILL SEND TEMPERATURES BELOW FREEZING FOR MOST LOCATIONS
BY WEDNESDAY MORNING...HOWEVER THIS COULD OCCUR MUCH FASTER IF
MODELS ARE UNDER DOING THE STRENGTH OF THE SHALLOW ARCTIC AIRMASS.
THIS IN SHORT IS THE PRIMARY FORECAST CHALLENGE MOVING FORWARD...
HOW STRONG AND EXPANSIVE WILL THE ARCTIC AIR BE WHEN IT MOVES INTO
THE REGION ON TUESDAY?

THE LOW-LEVEL AIRMASS THAT MOVES OUR WAY APPEARS TO BE IN NORTHERN
CANADA RIGHT NOW. MODELS ARE CURRENTLY DOING A DECENT JOB HANDLING
LOW-LEVEL TEMPERATURES THERE FOR NOW...BUT THAT DOES NOT MEAN
MODELS ARE NOT UNDER-FORECASTING THE STRENGTH OF THE COLD AIR
ONCE IT ARRIVES IN TEXAS. THE LOW-LEVEL CANADIAN AIRMASS WILL
MODIFY AS IT MOVES SOUTH ACROSS THE PLAINS EARLY NEXT WEEK...BUT
BY HOW MUCH? ONE OF THE KEY INGREDIENTS TO LOOK FOR IN TERMS OF
ARCTIC AIRMASS MODIFICATION POTENTIAL IS MODEL MID-LEVEL WIND
FIELDS. STRONG WESTERLY MID-LEVEL FLOW OVER THE ROCKIES BEHIND AN
ARCTIC AIRMASS WILL TEND TO ADIABATICALLY WARM THE ARCTIC AIR AS
IT MOVES SOUTH. THIS IS SIMPLY DUE TO WARMING AIR ASSOCIATED WITH
DOWNSLOPE WINDS IN THE LEE OF THE ROCKIES. AT THIS TIME...WHILE
THE ARCTIC AIRMASS IS MOVING SOUTH MONDAY AND TUESDAY...MOST
MODELS SHOW WEAK 700 MB FLOW...BUT MAYBE MORE
IMPORTANTLY...SUGGEST EASTERLY WINDS AS OPPOSED TO WESTERLY WINDS.
EASTERLY MID-LEVEL WINDS WILL TEND TO HELP KEEP THE ARCTIC AIRMASS
COLD BY PROVIDING CLOUD COVER AND COLD AIR DAMMING AGAINST THE
HIGH TERRAIN WHICH MAY ACTUALLY SPEED THE ARCTIC AIR UP. THE 12Z
ECMWF SOLUTION SEEMED TO HANDLE THIS PROCESS THE BEST...SO WENT
AHEAD AND NUDGED THE FORECAST TOWARDS THIS SOLUTION FOR TUESDAY
THROUGH THURSDAY.

IN GENERAL THE ECMWF SOLUTION IS A BIT FASTER WITH THE ARRIVAL OF
THE ARCTIC AIR ON TUESDAY...AND IS COLDER IN GENERAL WITH THE
FORECAST ONCE THE ARCTIC AIR IS IN PLACE. BOTH THE ECMWF AND GFS
INDICATE THAT THE DUTCH HARBOR UPPER TROUGH WILL CLOSE OFF INTO AN
UPPER LEVEL LOW OVER SOUTHERN CALIFORNIA BY TUESDAY NIGHT.
ASSUMING THIS OCCURS...THIS WOULD RESULT IN SOUTHWEST FLOW ALOFT
OVER THE SOUTHERN PLAINS...WHICH WOULD INDUCE A LONG PERIOD OF
WARM AIR ADVECTION OVER THIS SHALLOW ARCTIC AIRMASS BY THE EARLY
MORNING HOURS OF NEW YEAR`S EVE...ALL THE WAY THROUGH JANUARY 2ND.
WITH HIGHER CONFIDENCE IN SHALLOW ARCTIC AIR IN PLACE...BUT LOW
CONFIDENCE ON THE EXACT DETAILS OF THE VERTICAL TEMPERATURE
PROFILE 6-7 DAYS OUT...WENT AHEAD AND MENTIONED A 20 TO 30 PERCENT
CHANCE OF FREEZING RAIN OR LIGHT RAIN IN THE FORECAST OVER MUCH OF
NORTH AND CENTRAL TEXAS.

CONFIDENCE IN THE AMOUNT OF LIFT AVAILABLE FOR PRECIPITATION OVER
THE ARCTIC AIRMASS...AS WELL AS AVAILABLE MOISTURE FOR
PRECIPITATION REMAIN LOW AT THIS TIME FOR NEW YEAR`S EVE AND
NEW YEAR`S DAY. CONFIDENCE IN LIFT AND AVAILABLE MOISTURE
INCREASES QUITE A BIT ON JANUARY 2ND WHEN MODELS SUGGEST THE DUTCH
HARBOR UPPER LOW WILL MOVE OVER NEW MEXICO AND SPREAD STRONG LARGE
SCALE FORCING FOR ASCENT OVER THE ENTIRE CWA. UNFORTUNATELY AS
CONFIDENCE IN PRECIPITATION RISES...CONFIDENCE IN THE SHALLOW
ARCTIC AIRMASS REMAINING IN PLACE DECREASES. GFS AND ECMWF DYNAMIC
TROPOPAUSE MAPS INDICATE THAT THE CUT OFF UPPER LOW IS ISOLATED
FROM THE POLAR JET STREAM BY THE TIME IT MOVES EAST OVER THE
SOUTHWEST CONUS AND TOWARDS TEXAS ON NEW YEAR`S DAY AND JANUARY
2ND. ONCE THIS OCCURS...DOWNSTREAM AIRMASS MODIFICATION BECOMES
INCREASINGLY LIKELY...WHICH REALLY JUST MEANS THE ARCTIC AIR IS
MORE LIKELY TO WARM UP BECAUSE IT WILL NOT BE REINFORCED BY ANY
MORE COLD AIR FROM THE NORTH.

AT ANY RATE THE BASIC THREAT TO THE REGION FOR WINTRY WEATHER
LOOKS LIKE THIS:

ARCTIC AIR WILL BUILD IN TUESDAY/TUESDAY NIGHT WHILE VERY LIGHT
RAIN/DRIZZLE CHANCES INCREASE INTO THE MORNING HOURS ON NEW YEAR`S
EVE. WHEREVER LIGHT RAIN/DRIZZLE SETS UP...IT HAS A GOOD CHANCE AT
FREEZING UPON CONTACT WITH ELEVATED SURFACES.

CONFIDENCE IN PRECIPITATION AND PRECIPITATION AMOUNTS INCREASES
THROUGH JANUARY 2ND WHILE THE SHALLOW ARCTIC AIRMASS WILL SLOWLY
WARM UP. RAINFALL CHANCES LOOK TO BE HIGHEST WHILE ARCTIC AIR IS
STILL PROBABLY COLD ENOUGH TO FREEZE THINGS ON NEW YEAR`S DAY. BY
JANUARY 2ND...WIDESPREAD PRECIPITATION IS LIKELY...BUT IT MAY TEND
TO ALL FALL IN LIQUID FORM BY THAT TIME.

IN GENERAL...CONFIDENCE REMAINS TOO LOW TO EXPECT ANY MAJOR WINTER
WEATHER EVENT ACROSS NORTH OR CENTRAL TEXAS AT THIS TIME.
HOWEVER...WE WILL CONTINUE TO WATCH THIS PERIOD CLOSELY MOVING
FORWARD AS THE POTENTIAL FOR WINTRY IMPACTS ARE CERTAINLY THERE
FOR THE REGION DURING NEW YEAR`S EVE/NEW YEAR`S DAY FESTIVITIES.

CAVANAUGH

[Srain]

Our rollercoaster pattern continues as temperatures have rebounded a good 25-30 degrees from yesterdays lows as a potent Winter Storm is underway across New Mexico and the Southern Rockies. The upper low bringing snow across the higher terrain of Colorado and New Mexico will shift NE today with increasing moisture streaming off the Western Gulf setting the stage for showers and eventually some storms which may approach severe limits tomorrow afternoon and evening  across portions of SE Texas into SW and Central Louisiana.

 

 

 

 

A rather expansive upper trough that extends from NE Canada SW to near the Baja of NW Mexico looks to remain as pool of very chilly air is pushing S across the Canadian Prairies. The various computer models continue to struggle with the fast flow and how the next upper disturbance evolves that is currently taking shape near British Columbia. The guidance is in general agreement that this upper air disturbance will drop S through the Great Basin toward Southern California/Arizona on Monday. As the storm system plunges S, a powerful Arctic airmasss with its 1055mb+ Artic High will spread quickly S into Colorado/Wyoming and into the Central Plains. This very cold dense shallow air mass is expected to race S into Texas on Tuesday with the Arctic front modifying as it drops S across Texas. The fly in the ointment continues to be what happens to our West and just how fast or slow the upper low/disturbance ejects E. The various computer models have been slow to move the upper low/trough once it settles into NW Mexico/Southern Arizona and suggest it may even cut off from the main Northern stream flow. It is a typical computer model error to cut off upper air disturbances with a relative fast flow pattern in the medium range. It is also a know computer model error to under estimate very dense, cold and shallow Arctic airmasses. The Operational Global models as well as the short range meso guidance are in excellent agreement that a very strong 1055 t0 1060mb+ Arctic High is coming South. That much agreement bodes well that a strong push of very cold air is coming. The other details are still 4 to 5 days out regarding what happens to our West with the upper trough and any embedded disturbances riding over the cold, dense and shallow cold air at the surface. In fact we may not have a real solution to our sensible weather before 24 to 36 hours out as the guidance struggles with this very complicated pattern as we end December 2014 and ring in the New Year of 2015.

 

[bubba hotep]

This "event" is taking on a rather lame look. Not as cold and the main energy not kicking out in time to take advantage of what cold there is. Maybe over the weekend models will trend back towards a winter weather event.

[aggiegeog]

This "event" is taking on a rather lame look. Not as cold and the main energy not kicking out in time to take advantage of what cold there is. Maybe over the weekend models will trend back towards a winter weather event.

As we are discussing the models do not appear to be handling this pattern correctly.

[DFWWeather]

This "event" is taking on a rather lame look. Not as cold and the main energy not kicking out in time to take advantage of what cold there is. Maybe over the weekend models will trend back towards a winter weather event.

 

Most computer guidance is vastly underestimating the amount of dense cold air associated with this 1055+mb Arctic high, or its not really 1055+mb. Texas looks to take a direct hit with this, and I'm not buying the rapid modification of this airmass on the models, given the rapid delivery of it, the time of year coupled with easterly flow against the mountains (cold air damming). Nor am I buying the nosing of the coldest H85 temps into the Texas Panhandle and then retreating back north quickly. That almost never happens, unless said cutoff low is ejecting out. I smell huge temperature busts all over the upcoming week. Never was into a huge snow or ice event yet. I do see how some freezing drizzle or light freezing rain could be a problem for a lot of folks, we'll see.

 

EPO is tanking negative!

[Srain]

Most computer guidance is vastly underestimating the amount of dense cold air associated with this 1055+mb Arctic high, or its not really 1055+mb. Texas looks to take a direct hit with this, and I'm not buying the rapid modification of this airmass on the models, given the rapid delivery of it and the time of year coupled with easterly flow against the mountains. Nor am I buying the nosing of the coldest H85 temps into the Texas Panhandle and then retreating back north quickly. That almost never happens unless said cutoff low is ejecting out. I smell huge temperature busts all over the upcoming week. Never was into a huge snow or ice event yet. I do see how some freezing drizzle or light rain could be a problem for a lot of folks, we'll see.

 

EPO is tanking negative!

The pattern is ripe for over running. That is the key. Anytime we see excellent agreement even with the shorter range meso guidance of dropping a 1055 to 1060mb+ Arctic High into the Central Rockies and the front range of the Plains, that spells trouble E of the lee side of the Rockies all the way to Brownsville. Even the 700mb charts DO NOT show down sloping winds that would 'warm up' or modify the dense, cold shallow Arctic air. In fact additional snow is expected as an upslope easterly component virtually guarantees this air mass will not modify that much. There is a lot of embedded disturbances across the Central and Eastern Pacific that will likely spread from SW to NE over the shallow cold air mass at the surface. That tends to spell a light sleet/freezing rain/freezing drizzle event for much of our Region except for the higher elevations where a lot of snow is likely going to accumulate. The 'wild card' is whether or not a Coastal low/wave develops near Brownsville after the cold air is entrenched across the Region. That has been hinted via some of the guidance, but I would like to wait until Monday night before biting on any given solution other than the fact that it is going to get very chilly all the way to the NW Gulf Coast.

[DFWWeather]

The pattern is ripe for over running. That is the key. Anytime we see excellent agreement even with the shorter range meso guidance of dropping a 1055 to 1060mb+ Arctic High into the Central Rockies and the front range of the Plains, that spells trouble E of the lee side of the Rockies all the way to Brownsville. Even the 700mb charts DO NOT show down sloping winds that would 'warm up' or modify the dense, cold shallow Arctic air. In fact additional snow is expected as an upslope easterly component virtually guarantees this air mass will not modify that much. There is a lot of embedded disturbances across the Central and Eastern Pacific that will likely spread from SW to NE over the shallow cold air mass at the surface. That tends to spell a light sleet/freezing rain/freezing drizzle event for much of our Region except for the higher elevations where a lot of snow is likely going to accumulate. The 'wild card' is whether or not a Coastal low/wave develops near Brownsville after the cold air is entrenched across the Region. That has been hinted via some of the guidance, but I would like to wait until Monday night before biting on any given solution other than the fact that it is going to get very chilly all the way to the NW Gulf Coast.

 

Agreed! Notice some of the local DFW forecasters are calling for a very brief period of somewhat colder weather associated with this outbreak and have us back above normal next weekend (huge mistake - imo). I'm looking at the 10 day 500mb mean off the Penn State ewall and those patterns on all three models ECMWF/GFS/CMC look brutally cold which should carry us into the first week or so of January. I smell another Arctic blast possible?

[aggiegeog]

I think we will continue to see arctic outbreaks. The models have not figured it out but the natural state of the EPO has become negative and that will likely continue at least through this winter.

[bubba hotep]

As we are discussing the models do not appear to be handling this pattern correctly.

Yea, Steve and I must have been posting at the same time, didn't see his until I submitted mine. The thing that gives me pause is that the typically more progressive GFS is also pretty strongly in the slower camp. The 00z Euro ESP has DFW back towards 60 by thr end of next week but does push another cold surge down after that. A fair number of members bring some winter weather through with that later shot of cold.

[aggiegeog]

It seems odd to me for the upper trough to dig into the middle of the huge west coast ridge.

[Srain]

Agreed! Notice some of the local DFW forecasters are calling for a very brief period of somewhat colder weather associated with this outbreak and have us back above normal next weekend (huge mistake - imo). I'm looking at the 10 day 500mb mean off the Penn State ewall and those patterns on all three models ECMWF/GFS/CMC look brutally cold which should carry us into the first week or so of January. I smell another Arctic blast possible?

 

Very well could be...