Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 4

[Quixotic1]

my wife is saying at least two inches and thunder in frisco. of course im in indiana while this is going on

[Srain]

MESOSCALE DISCUSSION 0035
   NWS STORM PREDICTION CENTER NORMAN OK
   0632 AM CST TUE JAN 15 2013
  
   AREAS AFFECTED...PARTS OF NE TX...NRN LA...SRN AR AND ADJACENT AREAS
   OF THE MS DELTA
  
   CONCERNING...FREEZING RAIN
  
   VALID 151232Z - 151630Z
  
   SUMMARY...FREEZING RAIN IS EXPECTED TO DEVELOP ACROSS THE REGION
   THROUGH THE MID AND LATE MORNING HOURS...WITH CONVECTIVELY ENHANCED
   RATES OF .1 TO .3 INCHES PER HOUR POSSIBLE.
  
   DISCUSSION...DOWNSTREAM OF A VIGOROUS UPPER TROUGH NOW TURNING
   EASTWARD ACROSS THE SOUTHERN ROCKIES...LOWER/MID TROPOSPHERIC WARM
   ADVECTION WILL CONTRIBUTE TO STRENGTHENING AND CONSOLIDATING UPWARD
   VERTICAL MOTION ACROSS PARTS OF THE ARKLATEX EAST NORTHEASTWARD
   TOWARD THE MISSISSIPPI DELTA REGION THROUGH THE 15-18Z TIME FRAME.
   COUPLED WITH THE CONTINUING RETURN OF GULF MOISTURE ON SOUTHERLY
   FLOW...ABOVE A COLD/STABLE SURFACE BASED LAYER ENTRENCHED TO THE
   NORTH OF A STALLED SURFACE FRONT ACROSS THE NORTHWESTERN/NORTH
   CENTRAL GULF OF MEXICO...THIS WILL LEAD TO A DEVELOPING
   PRECIPITATION SHIELD.  CONVECTIVELY ENHANCED PRECIPITATION RATES ARE
   LIKELY AS MODEST STEEPENING OF MID-LEVEL LAPSE YIELDS WEAK
   CAPE...AND THERMODYNAMIC PROFILES THAT COULD BECOME SUPPORTIVE OF
   LIGHTNING /WEAK THUNDERSTORM ACTIVITY IS CURRENTLY OCCURRING ACROSS
   PARTS OF NORTH CENTRAL TEXAS/.  THOUGH MOST OF THE COLUMN BELOW 700
   MB WILL BE ABOVE FREEZING...AT LEAST A SHALLOW SURFACE BASED LAYER
   IS EXPECTED TO REMAIN BELOW FREEZING IN AREAS AFFECTED BY
   CLOUDS/PRECIPITATION...TO THE NORTH OF A LINE ROUGHLY FROM LONGVIEW
   TX THROUGH SHREVEPORT AND MONROE LA...INTO SOUTHERN ARKANSAS AND THE
   MISSISSIPPI DELTA...THROUGH AT LEAST MID DAY.  SIGNIFICANT ICING IS
   POSSIBLE...BUT MAINLY ON VEGETATION...POWER LINES AND ELEVATED ROAD
   SURFACES...AS GROUND TEMPERATURES REMAIN RELATIVELY WARM.
  
   ..KERR.. 01/15/2013
  
  
   ATTN...WFO...JAN...LZK...SHV...
 

[bubba hotep]

my wife is saying at least two inches and thunder in frisco. of course im in indiana while this is going on

About the same here, that puts my IMBY total at 7"+ so far this winter

[Srain]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
820 AM CST TUE JAN 15 2013

TXZ163-164-176-177-195>198-151630-
HOUSTON-TRINITY-MADISON-WALKER-BURLESON-BRAZOS-WASHINGTON-GRIMES-
INCLUDING THE CITIES OF...CROCKETT...TRINITY...GROVETON...
MADISONVILLE...HUNTSVILLE...CALDWELL...LAKE SOMERVILLE...
COLLEGE STATION...BRYAN...BRENHAM...NAVASOTA
820 AM CST TUE JAN 15 2013


...RAIN MIXED WITH SLEET POSSIBLE THIS MORNING...

POCKETS OF LIGHT RAIN THIS MORNING MAY BE MIXED WITH SLEET FOR
AREAS NORTH OF A BRENHAM TO NEW WAVERLY TO TRINITY LINE. THE RAIN
AND SLEET MIX WILL BE POSSIBLE THROUGH ABOUT 10 AM. TEMPERATURES
ARE ABOVE FREEZING SO THE PRECIPITATION IS NOT EXPECTED TO FREEZE
ON ROADS BUT ELEVATED SURFACES SUCH AS BRIDGES AND OVERPASSES
COULD BRIEFLY FREEZE EARLY THIS MORNING. ANY SLEET SHOULD BE
SHORT LIVED AND NO ACCUMULATIONS ARE EXPECTED. CAUTION IS ADVISED
ON AREA ROADS...BRIDGES AND OVERPASSES DUE TO WET AND POTENTIALLY
ICY CONDITIONS.
 

[Quixotic1]

About the same here, that puts my IMBY total at 7"+ so far this winter

 

I'm around 6".  Dusting in early Dec.  4" at Christmas.  Around 2" for this.  Much better than last year.  Much, much better. 

[bubba hotep]

From the FWD discussion, hmmm.....

 

REMAINDER OF THE FORECAST...ALL 15/00Z GUIDANCE INDICATES THAT THE

LARGE UPPER TROUGH TO OUR WEST WILL REMAIN POSITIVELY TILTED AS IT

MOVES OVER THE SOUTH PLAINS OVERNIGHT INTO WEDNESDAY MORNING. THIS

WILL RESULT IN SOME LIGHT RAINFALL WEDNESDAY MORNING SOUTHEAST OF A

CANTON TO WACO LINE ASSUMING THE MODELS ARE RESOLVING THIS TROUGHS

EVOLUTION WELL. WITH NO GUIDANCE OFFERING UP THE CLOSED LOW

SOLUTION ANYMORE...DO NOT HAVE ANYTHING IN THE FORECAST TO HANDLE

THIS NOW UNLIKELY ALTERNATIVE SCENARIO. IT SEEMS THAT AFTER THIS

MORNINGS COMPACT SHORTWAVE TROUGH MOVES NORTHEAST...THE LOWER

TROPOSPHERE WILL BECOME DOMINATED ONCE AGAIN BY COLD AIR ADVECTION

WHICH WOULD SERVE TO KEEP THE TROUGH POSITIVELY TILTED AS IT MOVED

OVER THE CWA. ONE IMPORTANT CAVEAT HERE...WILL HAVE TO SEE HOW

LONG AND INTENSE PRECIPITATION ACTUALLY IS ACROSS NORTH...CENTRAL

AND EAST TX TODAY. IF PRECIPITATION HANGS AROUND LONGER THAN

EXPECTED OR IS JUST MORE INTENSE THAN EXPECTED...PRECIPITATION

WILL RELEASE MORE LATENT HEAT INTO THE MIDDLE TROPOSPHERE THAN THE

MODELS WERE PLANNING ON. WITH NO GUIDANCE FAVORING THE CUT-OFF LOW

SOLUTION ANYMORE...ITS HARD TO IMAGINE WE GET ENOUGH LATENT HEAT

RELEASE TO RAISE THICKNESSES ENOUGH DOWNSTREAM TO HAVE AN IMPACT

ON THE TILT OF THIS TROUGH. HOWEVER IT IS THE ONE THING TO WATCH

FOR DURING THE DAY TODAY...IF DEVELOPING PRECIPITATION RESULTS IN

RIDGING OVER EAST TX...THE UPPER CLOUD COULD MAKE AN ATTEMPT AT

BECOMING NEUTRALLY TILTED OR CUTTING OFF AS IT MOVES TOWARDS THE

CWA OVER THE NEXT 24 HRS. WHILE UNLIKELY...WE WILL NEED TO WATCH

FOR THIS JUST IN CASE THE MODELS HAVE MISSED SOMETHING IMPORTANT

HERE.

[Srain]

Morning e-mail from Jeff:

 

Light freezing rain and freezing drizzle had developed over the northern counties of SE TX this morning. Temperatures at 500am were in the mid 30’s and have cooled to 32 at both Huntsville and Crockett. Wind devices at both sites have gone calm even though a decent N wind is blowing suggesting ice as formed and encased the anemometer. Profiles across the area continue to support mainly freezing rain and freezing drizzle north of a College Station to Huntsville to Trinity line where surface temperatures are at or below freezing. Ob sites have also been reporting a little bit of sleet in this area, but most of this is likely very short lived.
 
Should see surface temperatures rise above freezing by noon over those northern impacted areas with any ice melting. Main question then becomes tonight into Wednesday morning. Upper level storm system will be moving across TX tonight, but moisture throughout the air column will be decreasing as the stronger lift arrives. Surface temperatures are expected to run a few degrees cooler Wednesday morning than this morning suggesting at least the northern 1/3rd of the area (north of HWY 105) will be at or below freezing. Could see the light drizzle and light rain continue into the evening hours and then mainly end prior to the onset of any sub freezing temperatures over our northern counties. Profiles show the cold pocket of air aloft associated with the upper level system moving across the area early Wednesday into Wednesday and this will cool the entire air column (especially above the surface). Moisture looks extremely limited by this point and do not expect precipitation much beyond midnight tonight. Ingredients are not in phase to produce a winter weather event across SE TX tonight into early Wednesday….unless more moisture can be found and brought into the region Wednesday morning. 
 
Extended:
Clearing skies and much warmer weather for the end of the week into the weekend with highs reaching into the 60’s and lows in the 40’s.

[DFWWeather]

Think Arctic air for early next week not being handled well by the models. ECMWF is doing a pretty good job. I'm calling it now that DFW will fall below 20°F (officially at the Airport) for the first time this winter next week with at least one or possibly two days not rising above freezing. Pattern with polar vortex so far south correlates well with producing stout cold shot into north central portions of the state. If meridional flow intesifies, the outbreak could even be colder and push farther south into the state. Some of this low level cold air will head south anyway just on its on density and could push further south than what the models indicate. Could be an even colder shot of Arctic after this rotating down on backside of shortwave cutting up through Plains later next week.

[Portastorm]

Think Arctic air for next week not being handled well by the models. ECMWF is doing a pretty good job. I'm calling it now that DFW will fall below 20°F (officially at the Airport) for the first time this winter next week with at least one or possibly two days not rising above freezing. Pattern with polar vortex so far south will produce stout cold shot into north central portions of the state. If meriodional flow intesifies, the outbreak could even be colder and push farther south into the state.

 

I hope you're right ... Austin is anxiously awaiting a nice winter weather event.  Gotta start with subfreezing temperatures, first. 

[Ed Lizard]

I hope you're right ... Austin is anxiously awaiting a nice winter weather event.  Gotta start with subfreezing temperatures, first. 

 

Not really, you can have daytime temps near 45ºF under clear sun, no change in surface airmass, and if your dewpoints are in the teens or lower, with a fresh supply of dry air, you can evaporatively cool enough for happy precip.  I have seen it happen.

[Ed Lizard]

GFS, NAM, Canadian, trough doesn't start taking happier neutral, than negative tilt 'til leaving state, no happy fun sleet/snow day Thursday for the children.

 

 

BTW, I prefer my 16 day GFS wetter than this, and happiest fun cold is in the Northeast/Lakes.

[wxmx]

Think Arctic air for early next week not being handled well by the models. ECMWF is doing a pretty good job. I'm calling it now that DFW will fall below 20°F (officially at the Airport) for the first time this winter next week with at least one or possibly two days not rising above freezing. Pattern with polar vortex so far south correlates well with producing stout cold shot into north central portions of the state. If meridional flow intesifies, the outbreak could even be colder and push farther south into the state. Some of this low level cold air will head south anyway just on its on density and could push further south than what the models indicate. Could be an even colder shot of Arctic after this rotating down on backside of shortwave cutting up through Plains later next week.

Yep, it puzzles me a bit how a 1050+mb arctic high brings slightly below avg temps to the region...not that the 500mb is highly unfavorable...its ok, maybe a bit conducive even...the 1983 dec pattern was a lot worse, and look what happened...of course, that airmass was a lot denser/colder than what is modeled, but still.

[wxmx]

Figures to support my above post. The power of a dense siberian 1060+mb high is astounding...582+dm heights can't do anything to stop it.

 

12z Euro's 1051mb high is "shredded" to pieces in a more favorable 500mb pattern...and the Euro is the coldest in model world.

 

[Portastorm]

Sorry wxmx to ask to pretty much have you spell it out for me, but are you suggesting that it is questionable that a 1051mb high would be so quickly "shredded"  via the 500mb flow progged by the Euro?  It would seem such a strong high would plummet south, albeit perhaps a shallow Arctic airmass.  I'm trying to balance my weenie hopes with some met sensibility.

[wxmx]

Sorry wxmx to ask to pretty much have you spell it out for me, but are you suggesting that it is questionable that a 1051mb high would be so quickly "shredded"  via the 500mb flow progged by the Euro?  It would seem such a strong high would plummet south, albeit perhaps a shallow Arctic airmass.  I'm trying to balance my weenie hopes with some met sensibility.

Yep, you got it right...in the end I would think that it will be colder than progged...not historically cold, just colder.

[snowmanwx]

Here's another example: 

 

 

This Arctic invasion (0000 UTC 18 January 1994 shown) broke several all-time record low temperatures in the Midwestern and northeastern states, especially Indiana, Kentucky, and Ohio.  Northeastern Oklahoma endured as many as five consecutive days below freezing, dropping as low as 5°F: certainly uncomfortable but not record-breaking.  But the temperature stayed below freezing only two consecutive days in Oklahoma City and rose above that barrier on the coldest days in parts of southwest Oklahoma.  In Texas, the temperature plunged into the upper 10s in Dallas, near 20 in San Antonio, and a few degrees below freezing in Houston. 

 

What's the big difference between this episode and that of December 1983?  One factor that I notice is the progressiveness of the Pacific Northwest ridge.  In the 1983 example, it simply didn't exist until the Arctic high already slid down the Rockies into Texas; instead a 500-mb trough extends through the region.  In the 1994 example and in this forecast for next week, by contrast, the Pacific Northwest ridge moves quickly eastward, driving the coldest-cold air into the Midwest and away from the Southern Plains. 

[Srain]

^^

 

One tendency we need to monitor is just how strong the PNA ridge is and if the guidance is breaking it down too quickly or moving it too far E. I know the GFS and its ensembles tend to rush things a bit too fast and as of today, it certainly doesn't appear to be in a hurry to break down or move E.

[beavis1729]

I'm around 6".  Dusting in early Dec.  4" at Christmas.  Around 2" for this.  Much better than last year.  Much, much better. 

Chicago is at 1.3" so far this season, if it makes you feel any better.

 

Nice thread...I enjoy reading it.  And, congrats to all of those who saw snow today!  Hopefully some good old-fashioned arctic air pays all of us a visit. 

[wxmx]

Here's another example: 

 

This Arctic invasion (0000 UTC 18 January 1994 shown) broke several all-time record low temperatures in the Midwestern and northeastern states, especially Indiana, Kentucky, and Ohio.  Northeastern Oklahoma endured as many as five consecutive days below freezing, dropping as low as 5°F: certainly uncomfortable but not record-breaking.  But the temperature stayed below freezing only two consecutive days in Oklahoma City and rose above that barrier on the coldest days in parts of southwest Oklahoma.  In Texas, the temperature plunged into the upper 10s in Dallas, near 20 in San Antonio, and a few degrees below freezing in Houston. 

 

What's the big difference between this episode and that of December 1983?  One factor that I notice is the progressiveness of the Pacific Northwest ridge.  In the 1983 example, it simply didn't exist until the Arctic high already slid down the Rockies into Texas; instead a 500-mb trough extends through the region.  In the 1994 example and in this forecast for next week, by contrast, the Pacific Northwest ridge moves quickly eastward, driving the coldest-cold air into the Midwest and away from the Southern Plains. 

Yep, the Jan 1994 arctic outbreak is a good analog.

[DoctorMu]

Today's real time solution was considerably colder (and more wintry precip wise) than expected. We haven't risen above 36°F in CLL. As a young 'un we lived in Illinois for awhile. You don't forget those kinda clouds

Count this weenie on board the Siberian Express.

[DFWWeather]

KDFW NWS office seems to be underestimating next week's Arctic airmass on this afternoon's AFD. Additonally, they tend to be flip flopping with every model run. Yesterday afternoon vs this morning vs this afternoon. Mark my words, this will be the coldest air seen so far this winter at DFW. I think we will out do the low of 22°F and high of 32°F on Christmas Day, especially on the low.

[Quixotic1]

Chicago is at 1.3" so far this season, if it makes you feel any better.

 

Nice thread...I enjoy reading it.  And, congrats to all of those who saw snow today!  Hopefully some good old-fashioned arctic air pays all of us a visit. 

 

Unbelievable that Chicago is that low.  I think things will be looking up though. 

 

The folks in this thread are top notch.  What lacks in quantity, is definitely made up in quality. 

[Portastorm]

Today's real time solution was considerably colder (and more wintry precip wise) than expected. We haven't risen above 36°F in CLL. As a young 'un we lived in Illinois for awhile. You don't forget those kinda clouds

Count this weenie on board the Siberian Express.

 

Same here in Austin.  Progged high was 43.  We haven't risen above 38 degrees with thick, low overcast all day. 

[Quixotic1]

Today's real time solution was considerably colder (and more wintry precip wise) than expected. We haven't risen above 36°F in CLL. As a young 'un we lived in Illinois for awhile. You don't forget those kinda clouds

Count this weenie on board the Siberian Express.

Agreed, that It seems each system has been colder and wetter than progged since Christmas.  This one could change as well once things start moving south.  Shallow dense air mass and all that.       

[bubba hotep]

I'm around 6".  Dusting in early Dec.  4" at Christmas.  Around 2" for this.  Much better than last year.  Much, much better. 

 

Yeah, last year was brutal! The winter before that was really nice and we got around 12"+ out here in the south Lucas area. Then the winter before that was our last in the DC area and it was beyond epic.  My kids, 4 and 5, have twice seen a white Christmas and have only really experienced one bust of a winter.  I keep trying to explain to them that it doesn’t usually snow in the winter

[bubba hotep]

Agreed, that It seems each system has been colder and wetter than progged since Christmas.  This one could change as well once things start moving south.  Shallow dense air mass and all that.       

 

Pretty much everything has "overperformed" since that dusting blew through around Dec 8th. 

[Srain]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAKE CHARLES LA
657 AM CST WED JAN 16 2013

LAZ027>033-161500-
VERNON-RAPIDES-AVOYELLES-BEAUREGARD-ALLEN-EVANGELINE-ST. LANDRY-
INCLUDING THE CITIES OF...LEESVILLE...NEW LLANO...ALEXANDRIA...
PINEVILLE...MARKSVILLE...BUNKIE...COTTONPORT...SIMMESPORT...
MANSURA...DE RIDDER...OAKDALE...KINDER...VILLE PLATTE...MAMOU...
OPELOUSAS...EUNICE
657 AM CST WED JAN 16 2013

...FREEZING LIGHT RAIN OR DRIZZLE POSSIBLE OVER CENTRAL LOUISIANA...

PATCHY LIGHT RAIN OR DRIZZLE WILL CONTINUE FROM THE GULF
WATERS...THROUGH SOUTHWEST LOUISIANA AND INTO CENTRAL LOUISIANA.
WHILE TEMPERATURES ARE EXPECTED TO REMAIN ABOVE FREEZING OVER
SOUTH LOUISIANA...TEMPERATURES MAY DROP TO THE FREEZING MARK OVER
CENTRAL LOUISIANA. THUS THE POTENTIAL EXISTS FOR FREEZING RAIN OR
FREEZING DRIZZLE. WHILE ANY AMOUNTS WILL REMAIN ON THE LOW
SIDE...JUST A FEW HUNDREDTHS OF AN INCH...ELEVATED SURFACES...
BRIDGES AND OVERPASSES MAY BECOME ICE COVERED. USE EXTREME CAUTION
IF DRIVING OVER THE NEXT FEW HOURS.
 

[Portastorm]

Both the GFS and Euro operational runs sure but the kibosh on any hope for an impressive cold front next week for those of us in the Southern Plains. 

[Quixotic1]

Yeah, last year was brutal! The winter before that was really nice and we got around 12"+ out here in the south Lucas area. Then the winter before that was our last in the DC area and it was beyond epic.  My kids, 4 and 5, have twice seen a white Christmas and have only really experienced one bust of a winter.  I keep trying to explain to them that it doesn’t usually snow in the winter

 

Apparently the kids are good luck for you.   

Both the GFS and Euro operational runs sure but the kibosh on any hope for an impressive cold front next week for those of us in the Southern Plains. 

 

Yeah.  It looks grim.  I'd hold out hope but even the individual members seem pretty aligned on this thing not only going east, but not as cold as they thought.  Oh well.  There's always February. 

[wxmx]

Yep, it looks coolish to average... or in other words...meh.

 

AO will stay mostly negative for the foreseeable future so if and when a better 500mb pattern arises, the source of cold air will probably be mostly arctic. One thing I have noted is that there's mayhem in model world after day 8, nothing than a ridge in the arctic is common to all models. This usually means a change is about to occur.