Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 7

[aggiegeog]

Angel Fire, NM has to have some of the largest daily temperature swings of anywhere. Yesterday was a great example with a low of -32 and a high of 25 back down to -25 this morning.

[DFWWeather]

The set up for Saturday looks almost ideal for big snow potential across northern Texas. We have An Arctic intrusion followed by a vigorous shortwave with STJ support. As always it will be about timing. The following storm also has some potential but it looks weaker and may not have enough cold by the time it arrives.

 

Not really. By the time temperatures get cold enough for wintry precipitation, it will be battling the intrusion of much drier air. Secondly, the models, with every new run, are backing off on the cold air. The brunt of it will slide north and east of Texas as that is what the flow will dictate, plus the source regions are just not that cold. Additonally, this airmass is more polar in nature rather than true Arctic air.  Temperatures at the surface continue to moderate. Most data is now suggesting that DFW will barely, if at all, reach freezing (today's 0z ECMWF say no freezing temps at DFW). This will not be cold enough for a significant winter weather episode. Temperatures really need to be in the mid 20s for anything to be substantial, or we need a very heavy snow event to offset melting, and I just don't see that in the cards. Furthermore, the ECMWF/GFS really keeps the 540 thickness line north of the Metroplex or briefly touching northern suburbs (while surface temps well above freezing), so nothing more than a light cold rain possibly mixed with a flurry is about all that I see.

[bubba hotep]

Some subtle but significant changes on the 12z GFS. H5 looks better, could be slower and kicking negative sooner but a step in the right direction, moisture return is better, surface is colder. Really wouldn't have to trend much more to be something interesting for the northern counties. As it is now, the Red River area scores and it looks legit based on everything.

[aggiegeog]

Not really. By the time temperatures get cold enough for wintry precipitation, it will be battling the intrusion of much drier air. Secondly, the models, with every new run, are backing off on the cold air. The brunt of it will slide north and east of Texas as that is what the flow will dictate, plus the source regions are just not that cold. Additonally, this airmass is more polar in nature rather than true Arctic air.  Temperatures at the surface continue to moderate. Most data is now suggesting that DFW will barely, if at all, reach freezing (today's 0z ECMWF say no freezing temps at DFW). This will not be cold enough for a significant winter weather episode. Temperatures really need to be in the mid 20s for anything to be substantial, or we need a very heavy snow event to offset melting, and I just don't see that in the cards. Furthermore, the ECMWF/GFS really keeps the 540 thickness line north of the Metroplex or briefly touching northern suburbs (while surface temps well above freezing), so nothing more than a light cold rain possibly mixed with a flurry is about all that I see.

Significant cold only requires about 35 or so degrees as long as it is falling at a good clip. It is incredibly rare to see significant snow around here with temps below around 28. A polar or even Pacific air mass with strong upper level support is plenty cold for snow around here in January. I am not saying to forecast a foot of snow though that is not off the table with this pattern. I want to look back on 2/10/10, but everything I am hearing is that this event is looking very similar to how that one set up though this storm currently looks to be entering the US at a higher latitude but like many storms do this one could easily dig further south. Still have four days to see how things develop.

[DFWWeather]

Significant cold only requires about 35 or so degrees as long as it is falling at a good clip. It is incredibly rare to see significant snow around here with temps below around 28. A polar or even Pacific air mass with strong upper level support is plenty cold for snow around here in January. I am not saying to forecast a foot of snow though that is not off the table with this pattern. I want to look back on 2/10/10, but everything I am hearing is that this event is looking very similar to how that one set up though this storm currently looks to be entering the US at a higher latitude but like many storms do this one could easily dig further south. Still have four days to see how things develop.

 

Yes, I know all that, but with this system there is currently no data suggesting it will be a heavy precipitation producer. You will need that to offset melting with a surface temperature of 35°F. The odds are very much against a setup like we had in 2010. They are extremely rare, and that system doesn't look that impressive to me as of yet. You have to remember there will be a Pacific airmass that moves into North Texas on Friday effectively shutting down moisture transport from the Gulf before the colder air arrives Friday night/early Saturday which will only scour moisture out more. Thus, the system will need to work with whatever moisture is left over from return flow today through Thursday, providing the disturbance Thursday doesn't exhaust that moisture. I really feel this system will be moisture starved. Believe me, I will be all about hyping this if I thought it was the real McCoy, I just don't think so right now.

[bubba hotep]

It will be interesting to see what Dr No has to say at 12z. The 6z GFS Para looked pretty encouraging as well.

[bubba hotep]

Yes, I know all that, but with this system there is currently no data suggesting it will be a heavy precipitation producer. You will need that to offset melting with a surface temperature of 35°F. The odds are very much against a setup like we had in 2010. They are extremely rare, and that system doesn't look that impressive to me as of yet. You have to remember there will be a Pacific airmass that moves into North Texas on Friday effectively shutting down moisture transport from the Gulf before the colder air arrives Friday night/early Saturday which will only scour moisture out more. Thus, the system will need to work with whatever moisture is left over from return flow today through Thursday, providing the disturbance Thursday doesn't exhaust that moisture. I really feel this system will be moisture starved. Believe me, I will be all about hyping this if I thought it was the real McCoy, I just don't think so right now.

The models have been too aggressive with scouring out moisture here lately. However, it hasn't really mattered because the timing and orientation of disturbances has been so poor. It really wouldn't take big changes to the 12z GFS to make something happen. Too bad 18z will probably be a dry positive tilted warm system

[aggiegeog]

In 2010 there was a lot of talk about limited moisture leading up to the event and models showing little to no accumulations.

 

Here is the 12Z GFS 500mb chart for Friday night

 

Here is the 500 mb chart for the morning of 2/11/2010

 

Incredibly similar pattern the current storm is shown to be a bit stronger, but also a bit further north. Most features are very similar across NA to that day though everything is a bit more amplified with the current set up.

[DFWWeather]

 

In 2010 there was a lot of talk about limited moisture leading up to the event and models showing little to no accumulations.

 

Here is the 12Z GFS 500mb chart for Friday night

 

Here is the 500 mb chart for the morning of 2/11/2010

 

Incredibly similar pattern the current storm is shown to be a bit stronger, but also a bit further north. Most features are very similar across NA to that day though everything is a bit more amplified with the current set up.

 

 

And the 12z ECMWF operational comes in even warmer than 0z and drier with nearly 0 chances for snow for the Metroplex on Saturday.

[Quixotic1]

The pattern should be awesome but it isn't.  Just isn't cold enough yet.  A change is a foot though.  The models are all over the place and inconsistent.  Hopefully not back to the furnace.  PNA still looking good.  AO still negative.  EPO is the definition of "meh'.  

 

To aggiegeog's point, a lot of the stuff in 09-10 came out of nowhere.  Two hours before the snow began on the February storm, we were slated for 1 - 2".     

[bubba hotep]

In 2010 there was a lot of talk about limited moisture leading up to the event and models showing little to no accumulations.

Here is the 12Z GFS 500mb chart for Friday night

Here is the 500 mb chart for the morning of 2/11/2010

Incredibly similar pattern the current storm is shown to be a bit stronger, but also a bit further north. Most features are very similar across NA to that day though everything is a bit more amplified with the current set up.

Looking at those images you can see how everything has to workout right for us to get snow. In that 12z GFS image, things west of the Mississippi River look pretty good. From the River looking east... Meh.

[aggiegeog]

18Z still looks good, just need a bit cooler surface and we are set. More moisture would help also.

[bubba hotep]

18Z still looks good, just need a bit cooler surface and we are set. More moisture would help also.

I actually like the H5 setup at 18z better than 12z. The 12z Para GFS is even better looking. Obviously the Euro not being on board is concerning but if there is one thing the GFS might be able to handle better than the Euro, it is energy coming out of the SW across Texas.

ETA: Granted that even with the "better" GFS runs we still have a lot of issues but our window is closing fast (hopefully only temporarily)

[raindancewx]

AMO value for December is the highest since 1998 by this dataset: 

http://www.esrl.noaa.gov/psd/data/correlation/amon.us.long.data

 

For Nov-Dec averaged, closest six El Nino years are:

1945 1951 1953 1958 2004 2006

 

Six closest El Nino years to Dec 15 AMO value:

1941 1951 1953 1958 2004 2006

 

Closest Novembers in El Nino years:

1945 1951 1953 1958 2004 2006

 

The Nov+Dec matches, and the Nov matches are very close to what Albuquerque has observed to date.

[raindancewx]

[bubba hotep]

It is becoming obvious that the models can't handle the current pattern beyond a few days and that the warmer dryer runs are the ones to bet on.

 

We are slipping into a hideous pattern... 

[ams30721us]

Interesting to watch how this plays out. The intro of a Low pressure tracking along the coast def. captures my interest in ETX for Saturday evening.

 

 

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
417 AM CST WED JAN 13 2016

.DISCUSSION...
ANOTHER MORNING OF CHILLY TEMPS AND CLEAR SKIES IS UPON US...AS
HIGH PRESSURE REMAINS ANCHORED AT THE SFC OVER THE REGION. ALOFT
THE FLOW REMAINS SPLIT WITH AN UPPER LOW CUT OFF OVER NRN
MEXICO...RIDGING OVER THE MOUNTAIN WEST...AND A BROAD-SCALE TROF
OVER THE ERN HALF OF THE CONUS. WV IMAGERY SHOWS A SHORTWAVE
EJECTING INTO THE CENTRAL PLAINS THIS MORNING...AND THIS WILL MAKE
ITS WAY ACROSS OUR REGION LATE TONIGHT...ALTHOUGH WE WILL NOTICE
NOTHING MORE THAN SOME HIGH CLOUDS.

HOWEVER...AS WE MOVE INTO THURSDAY...THE UPPER LOW OVER NRN
MEXICO WILL MAKE ITS WAY INTO TX AND BRING A COLD FRONT AND SOME
LOW-END CHANCES FOR RAIN FOR LATE THURSDAY INTO FRIDAY. MOST OF
THE RAIN WILL BE CONFINED TO THE ERN HALF OF OUR REGION...AS
MOISTURE RETURN WILL BE MORE ENHANCED OVER THESE AREAS.

RIGHT ON THE HEELS OF FRIDAY'S SHORTWAVE WILL BE ANOTHER MUCH
STRONGER DISTURBANCE THAT WILL MAKE ITS WAY ACROSS OUR REGION
SOMETIME SATURDAY. MODEL TIMING AND STRENGTH DIFFER SOMEWHAT...THE
EURO BEING QUITE A BIT SLOWER THAT THE GFS/NAM SOLUTIONS. WHAT IS
SIMILAR BETWEEN THE MODELS IS THAT BOTH THE GFS AND EURO ARE
INDICATING PRECIP AND VERY COLD AIR THROUGHOUT THE COLUMN AS THIS
DISTURBANCE MOVES ACROSS THE NRN GULF COAST. THIS INDICATION HAS
BEEN CONSISTENT OVER THE LAST FEW MODEL RUNS...AND A CHECK OF FCST
SOUNDINGS CORROBORATES THE NOTION THAT WE MAY NOT SEE ONLY LIQUID
PRECIP DURING SATURDAY. HAVE INTRODUCED SOME SNOW INTO THE FCST
FOR SATURDAY AS A RESULT...BUT HAVE KEPT POPS LOW AND
ACCUMULATIONS AT ZERO. SFC TEMPS ARE EXPECTED TO REMAIN WELL ABOVE
FREEZING...AND UNLESS SNOWFALL RATES ACROSS OUR NRN SECTIONS ARE
VERY HIGH...ANY SNOW THAT FALLS WILL LIKELY QUICKLY MELT. FURTHER
S IN THE I-20 CORRIDOR...HAVE GONE WITH A RAIN/SNOW MIX...AND
SNOW ACCUMULATION THIS FAR S SEEMS IMPOSSIBLE WITH TEMPS IN THE
MID 40S. WE WILL SHOO ANY PRECIP OUT OF OUR REGION BY LATE
SATURDAY NIGHT...AND HIGH PRESSURE WILL SETTLE IN OVER THE REGION
FOR THE REST OF THE WEEKEND.

YET ANOTHER SHORTWAVE IS FCST TO MOVE ACROSS THE REGION DURING
MONDAY AND MAY BRING ANOTHER ROUND OF LIGHT PRECIP /POSSIBLY OF
THE FROZEN TYPE/ TO THE REGION. HOWEVER...WITH THIS
DISTURBANCE...MOISTURE SEEMS MORE LIMITED THAN WITH SATURDAY'S.
HAVE JUST KEPT SLIGHT CHANCES FOR RAIN IN THE GRIDS FOR NOW...AND
WILL MAKE MORE FINE TUNINGS IN LATER PACKAGES AS WE GET CLOSER TO
MONDAY.

SW FLOW ALOFT AND WARMING TEMPS WILL CARRY US THROUGH THE END OF
THE FCST PD.

[Srain]

MEX/MAV/MOS temperature guidance continues to bust way too warm in SE Texas. Another frost this morning across NW Harris County.

[aggiegeog]

Interesting to watch how this plays out. The intro of a Low pressure tracking along the coast def. captures my interest in ETX for Saturday evening.

Everything looks good for light snow except for that temps below 925mb are above freezing. If we can get some extra moisture maybe heavier precip rates could bring down the temp from near 40 to the mid 30s which could allow the snow to stick by cooling the ground some more and accumulating faster than it melts. Right now the sweet spot looks to be along I-30 if there is one. Still plenty of time for things to shift.

[bubba hotep]

Everything looks good for light snow except for that temps below 925mb are above freezing. If we can get some extra moisture maybe heavier precip rates could bring down the temp from near 40 to the mid 30s which could allow the snow to stick by cooling the ground some more and accumulating faster than it melts. Right now the sweet spot looks to be along I-30 if there is one. Still plenty of time for things to shift.

 

Para GFS continues to be one of the best looking solutions, but it is hard to tell what the surface temps are. Like you said, meager rates and temps in the upper 30s or 40s just means we have snow melting kind of near the surface and we get some sprinkles. The Euro keeps the freezing level between 850 and 700 with the surface near 40 and essential nothing more than sprinkles.

 

Anyway, here is the 06z Para GFS

 

[bubba hotep]

Looks like the 12z GFS is coming in a bit colder with a few other minor changes... Slightly more interesting than the last couple of runs

ETA: maybe an inch for some of the northern burbs?

[aggiegeog]

Looks like the 12z GFS is coming in a bit colder with few other minor changes... Slightly more interesting than the last couple of runs

It does look to be trending in our direction. Still looks like it keeps any accumulations north of I-30 primarily. More moisture and more surface cold are good trends though.

[jm1220]

MEX/MAV/MOS temperature guidance continues to bust way too warm in SE Texas. Another frost this morning across NW Harris County.

29 at the airport this morning in Austin.

[bubba hotep]

Euro doesn't budge and still keeps the system weak. GFS vs. Euro inside 90 hrs...

ETA: even if we go with the Euro bias of being less progressive than the GFS, the s/w is still much weaker. Not sure that a faster ejection that keeps it from getting crushed helps us any.

[raindancewx]

PDO rose a bit in December, to 1.01.

 

It was 2.51 in Dec 2014 though...so still way closer to neutral than last year.

 

http://research.jisao.washington.edu/pdo/PDO.latest

[ams30721us]

Afternoon update from SHV: (clearly leaning more GFS-ish and GEFS here.

 

Good afternoon Shreveport partners,

Timing and Overview:

As very cold air moves across the region, the lower atmosphere will chill below freezing after sunset. This will allow for precipitation to transition from rain to snow.

Four State Impacts:

Expected Accumulations:

Although snowfall amounts will be light, accumulations may be possible on bridges and overpasses.

Impacts:

Snow accumulations could make travel extremely dangerous on elevated bridges and roadways after midnight through mid-morning Sunday.

Additional updates will be emailed as staffing/time permits.  Please refer to the weekly webinar at 10 AM Thursday for more information. 

[bubba hotep]

NWS Fort Worth ‏@NWSFortWorth  36m36 minutes ago

In 2015, there were 35 fatalities from tornadoes in the U.S. Nearly half (16) occurred in North & Central Texas.

[Srain]

Liking the Updated Day 8+ and Day 11+ Analogs. Some memorable snow events in those years across SE Texas in the late January/February timeframe...

[bubba hotep]

12z Para GFS looks pretty good again, it has been consistent.

 

 

[bubba hotep]

On my phone at swim practice but it looks like the 18z GFS was a step back from 12z. FWD mentioned snow in the afternoon AFD but didn't really get into details. We miss you DC!