Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 8

[aggiegeog]

 

27 minutes ago, bubba hotep said:

First fantasy snow storm for N. Texas on the 06 GFS!  

Saw that. If the surface high can strengthen a bit more than shown on this run I will have more faith in it, but awesome to look at modeled snow.

[bubba hotep]

Most of the models keep storms east of DFW today but maybe we can score something out my way. The 00z WxBell Euro WRF is farther west with storms and seems to support the current SPC D1 graphic:

 

[bubba hotep]

Latest thinking from FWD:

[bubba hotep]

The 09z SREF pops a 45 Sig Tor Ing contour over the eastern 1/3 of DFW this evening. 

[Chargers09]

I was going to say, the recent runs seem to be slowing down the dry line just a bit, which may help those of us on  the fringe.

 

First severe weather day for me down here since moving from Detroit. Looking forward to a decent round of storms in SA.

[bubba hotep]

 MESOSCALE DISCUSSION 1822
   NWS STORM PREDICTION CENTER NORMAN OK
   0531 PM CST TUE NOV 22 2016

   AREAS AFFECTED...PARTS OF NORTH CENTRAL TEXAS INTO EAST CENTRAL
   OKLAHOMA

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 222331Z - 230100Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...A COUPLE OF DISCRETE STRONG TO SEVERE STORMS MAY DEVELOP
   ACROSS PARTS OF NORTH CENTRAL TEXAS THROUGH SOUTH CENTRAL AND EAST
   CENTRAL OKLAHOMA WITHIN THE NEXT COUPLE OF HOURS.  IT SEEMS MORE
   PROBABLE THAT A WATCH MAY BE NEEDED LATER THIS EVENING TO THE SOUTH
   AND EAST OF THE AREA CURRENTLY OUTLINED.  HOWEVER TRENDS WILL
   CONTINUE TO BE MONITORED.

   DISCUSSION...A SURFACE COLD FRONT IS READILY EVIDENT IN
   OBSERVATIONAL DATA ADVANCING SOUTHEASTWARD...AT NEAR 20 KT...ACROSS
   PARTS OF WESTERN OKLAHOMA AND NORTHWEST TEXAS.  AT THIS RATE...IT MAY
   BEGIN OVERTAKING THE DRYLINE...NOW WEST/NORTHWEST OF THE DALLAS/FORT
   WORTH METROPLEX INTO AREAS NEAR/JUST EAST OF THE OKLAHOMA CITY...
   TOWARD 01-02Z...WHEN FORCING FOR ASCENT MAY SUPPORT INCREASING
   THUNDERSTORM ACTIVITY AS IT ENCOUNTERS MODEST POTENTIAL INSTABILITY.

   LATEST GUIDANCE SUGGESTS THAT BOUNDARY LAYER WARMING AND MOISTENING
   HAS CONTRIBUTED TO A CORRIDOR OF MIXED LAYER CAPE UP TO 500 J/KG...
   AHEAD OF THE DRYLINE ACROSS NORTH CENTRAL TEXAS THROUGH SOUTH
   CENTRAL AND EAST CENTRAL OKLAHOMA.  IN THE PRESENCE OF THIS
   INSTABILITY...IT IT DOES NOT APPEAR OUT OF THE QUESTION THAT WEAK
   MID-LEVEL COOLING AND FORCING FOR ASCENT ASSOCIATED WITH LOW-LEVEL
   WARM ADVECTION COULD CONTRIBUTE TO DISCRETE STORM DEVELOPMENT IN
   ADVANCE OF THE ARRIVAL OF THE FRONT.  IF THIS OCCURS...VERTICAL SHEAR
   BENEATH 50+ KT CYCLONIC/SOUTHWESTERLY 500 MB FLOW PROBABLY IS
   SUFFICIENT FOR SUPERCELL STRUCTURES.  

   LARGER LOW-LEVEL HODOGRAPHS ASSOCIATED WITH A 40 KT SOUTHERLY 850 MB
   JET ARE GENERALLY OFF TO THE EAST (JUST EAST OF DALLAS INTO THE
   OZARK PLATEAU)...WHICH SEEMS LIKELY TO LIMIT ANY TORNADIC POTENTIAL...
   AT LEAST INITIALLY.  HOWEVER...STRONGER DISCRETE STORMS MAY BE
   CAPABLE OR PRODUCING SEVERE HAIL AND LOCALLY STRONG SURFACE GUSTS.

   ..KERR/GUYER.. 11/22/2016

[bubba hotep]

There are some quirks with this new setup that bug me. Anyway, here is the graphic:

 

[raindancewx]

This is an interesting forecast idea - and consistent with what I put out in October:

- Warm early

- Colder late

- Lots of variability for where cold/warmth is in any given moment

https://riskpulse.com/blog/2016-2017-winter-weather-outlook/

[bubba hotep]

Watching the area from Ardmore,OK back down to the SW and starting to see some signs of life.

[bubba hotep]

[aggiegeog]

I got about 2" of rain from this system and the NM mountains got 3-6" of snow out of it. 

The pattern the models are showing with blocking over the top and low heights over the SW should result in a snowy December for the SW and frequent precip in the Southern Plains with cold coming later in the month for the S Plains as a -EPO develops.

[Chargers09]

Day 6 severe threat. Looks intriguing.

[bdgwx]

I was getting ready to mention that as well. A vigorous trough with lots of kinetic energy at all levels colocated with adequate instability could mean trouble if many of the pieces come together in the right way. It might be more than just D6 to keep an eye on as well. There are a lot of pieces in play though so confidence seems low to me.

[raindancewx]

Looking back at non-El Nino years that were relatively wet in Albuquerque during Sept-Nov produces an interesting list of years:

1935, 1938, 1978, 1983, 1988, 1992, 1998. Barring more rain, or our first snow this month, those years had 2.4-3.2 inches of precipitation from Sept-Nov. We're at 2.8 inches of precip in Sept-Nov 2016. I consider 1938, 1983, 1988, 1998 to be La Ninas. 1992 & 1935 are sort of warm Neutrals that wanted to be El Ninos, with 1978 following a double El Nino as a Neutral year. This is probably the wettest November NM has ever had in a La Nina, so blending in Neutral years seems appropriate. 

1978, 1983, 1988, 1992, 1998 - these years all followed an El Nino.

Pretty cold winter in the US if you blend those seven years together in the winter. Most areas 1-3F below normal, 3-5F below in Montana and the Upper Midwest, +/-1F in the SE. Very wet in much of the west & the east, drier from El Paso to Detroit. 

 

[bubba hotep]

Both the Euro EPS and GEFS are building some nice anomalies in our source region by the end of the runs. Could be a legit artic dump around mid December? 

[raindancewx]

Panel A is the best match to my mean highs from June-Nov carried forward to Dec-Feb

Panel B is the best match from June-Sept mean highs, the monsoon, ENSO, years since ABQ had >9.6" snow, and the monsoon+ENSO

Panel C is the best match for my winter ocean expectations - Cold Neutral to Weak La Nina, Modoki, Neutral PDO, Warm AMO, after two El Ninos, Dry Monsoon

Panel D is the best match for borderline La Ninas only: -0.4C to -0.6C in DJF

So far, A has been pretty good for Nov, with B good for Oct. My historical testing of these methods show "C" should become most accurate later in the winter, with "B" fading after December to irrelevance. D should be relatively decent. But I lean towards a split of "A" & "C" for the winter, plus 1-2F in the SE. Essentially, A early, then C late.

Anyway, best bet for the West:

WA/OR: slightly cooler than normal (-0F to -2F)

ID/WY/MT: pretty cold (-2F to -4F)

CO/WY: cool (-1F to -3F)

CA: normal (-1F to +1F)

AZ/NM/NV: normal (-2F to +2F) 

[bubba hotep]

Looks like an active couple of days on tap:

[Quixotic1]

On 11/25/2016 at 9:35 PM, raindancewx said:

Panel A is the best match to my mean highs from June-Nov carried forward to Dec-Feb

Panel B is the best match from June-Sept mean highs, the monsoon, ENSO, years since ABQ had >9.6" snow, and the monsoon+ENSO

Panel C is the best match for my winter ocean expectations - Cold Neutral to Weak La Nina, Modoki, Neutral PDO, Warm AMO, after two El Ninos, Dry Monsoon

Panel D is the best match for borderline La Ninas only: -0.4C to -0.6C in DJF

So far, A has been pretty good for Nov, with B good for Oct. My historical testing of these methods show "C" should become most accurate later in the winter, with "B" fading after December to irrelevance. D should be relatively decent. But I lean towards a split of "A" & "C" for the winter, plus 1-2F in the SE. Essentially, A early, then C late.

Anyway, best bet for the West:

WA/OR: slightly cooler than normal (-0F to -2F)

ID/WY/MT: pretty cold (-2F to -4F)

CO/WY: cool (-1F to -3F)

CA: normal (-1F to +1F)

AZ/NM/NV: normal (-2F to +2F) 

If I were a betting man, I'd bet on panel D.  The strength of last year's Nino with a pretty strong jet leads me to believe cold will be more zonal than not.  

[bubba hotep]

Looks like the main threat will be in E. Texas and Louisiana tomorrow but maybe some thunder for the norther burbs of DFW late tonight:

[DFWWeather]

Pattern starting to look interesting on 12z ECMWF for this weekend. Quite a bit colder than the 12z GFS, especially in upper levels. Looks like a raw, chilly, wet weekend with temps in the 40s for DFW for highs and lows in the 30s. Also, both the GFS and ECMWF are trending to what could be a bona fide Arctic blast by the December 10ish timeframe. ECMWF has nice little system with the cold air too on its D10! Could December tank like '83?

[aggiegeog]

I have been telling people to not sleep on the potential for snow this weekend. It is not likely, but these type systems that dive into Mexico this time of year tend to surprise. And if it does come through at night then our chances are even better. I will continue to watch it. 

This will be followed by true Arctic air a few days later and we will watch to see if we can get a shortwave in the cold air.

[bubba hotep]

1 hour ago, DFWWeather said:

Pattern starting to look interesting on 12z ECMWF for this weekend. Quite a bit colder than the 12z GFS, especially in upper levels. Looks like a raw, chilly, wet weekend with temps in the 40s for DFW for highs and lows in the 30s. Also, both the GFS and ECMWF are trending to what could be a bona fide Arctic blast by the December 10ish timeframe. ECMWF has nice little system with the cold air too on its D10! Could December tank like '83?

'83 is an analog that keeps coming up when I bounce stuff around. However, people on the Twitter act like only a true weenie would bring it up. One thing is for sure, the 12z Euro EPS keeps our source region below normal the entire run. That was our biggest issue last winter, there was no cold up there when the pattern did get favorable. 

[raindancewx]

I was hindcasting my "objective" match testing the other day by mean highs, and although it doesn't work nationally, it does seem to show some skill from roughly TX to AZ to OK to Southern UT/CO/NV, and then quite a bit of skill the closer you get to ABQ. It doesn't really show any skill for precip, just temperatures.

What I wanted to show though, was that last year, the temperature profile behaved more like a blend of La Nina years from June-November, and then remained La Nina-ish/warm in Winter and to a lesser extent Spring. The temperature blend this year, despite being nominally in a La Nina, is much more of a weak El Nino / warm Neutral signal, which favors a much colder winter, maybe ~2.5-3.5F colder than last year.

The six closest mean high transitions last year from June to November favored a winter (Dec-Feb) mean high of ~50.9F in Albuquerque. It was 51.4F. The average is 49.5F. So the method identified slightly warmer than normal correctly. This year, the method says 48.6F - which is colder than normal, and 2.4F colder than last year.

 

[Quixotic1]

3 hours ago, bubba hotep said:

'83 is an analog that keeps coming up when I bounce stuff around. However, people on the Twitter act like only a true weenie would bring it up. One thing is for sure, the 12z Euro EPS keeps our source region below normal the entire run. That was our biggest issue last winter, there was no cold up there when the pattern did get favorable. 

I've been thinking about 83.  I'd be genuinely interested to see how extreme it was in terms of averages.  I've got all that data on a csv file so I can probably put it on a distribution easy enough.

[raindancewx]

Some flurries around Albuquerque tonight. Don't think it stuck anywhere - very light, above freezing. Always amazing to watch the dry air do it's thing, went from 37F with a 27F dew point to 35F with a 29F dew point and snow in about two minutes. Fell to 33F with a 30F dew point before it stopped snowing.

[aggiegeog]

10 hours ago, Quixotic1 said:

I've been thinking about 83.  I'd be genuinely interested to see how extreme it was in terms of averages.  I've got all that data on a csv file so I can probably put it on a distribution easy enough.

December is sure looking like 83 in general. The extremes of the heart of that outbreak will be hard to ever replicate though. A 580+ dm 500mb ridge will into Alaska is something we will be lucky to ever see especially coupled with a cold background state.

[DFWWeather]

Today's 0z ECMWF is down to -8.5°C at H85 for the potential Arctic blast December 8th through 10th. If that were to verify, that would mean the coldest air at DFW in nearly 2 years. Which, of course, isn't saying much as the lowest temp all last winter was an unprecedented 27°F and we had no days below 40°F for highs. Who knows what is going on with today's 0z and 6z operational GFS. It seems to be odd with no Arctic air as the last several runs have had it.

[aggiegeog]

24 minutes ago, DFWWeather said:

Today's 0z ECMWF is down to -8.5°C at H85 for the potential Arctic blast December 8th through 10th. If that were to verify, that would mean the coldest air at DFW in nearly 2 years. Which, of course, isn't saying much as the lowest temp all last winter was an unprecedented 27°F and we had no days below 40°F for highs. Who knows what is going on with today's 0z and 6z operational GFS. It seems to be odd with no Arctic air as the last several runs have had it.

Yea, for now I am tossing the recent GFS runs out. -40F air over NW Canada doesn't just fade away especially not with a -EPO look.

[bubba hotep]

1 hour ago, DFWWeather said:

Today's 0z ECMWF is down to -8.5°C at H85 for the potential Arctic blast December 8th through 10th. If that were to verify, that would mean the coldest air at DFW in nearly 2 years. Which, of course, isn't saying much as the lowest temp all last winter was an unprecedented 27°F and we had no days below 40°F for highs. Who knows what is going on with today's 0z and 6z operational GFS. It seems to be odd with no Arctic air as the last several runs have had it.

12z GFS looks like it keeps DFW below 40 for the high next Thursday. It is a ways off but there is growing agreement across operational and ensemble models that DFW could see the coldest air in years with this shot.

[aggiegeog]

39 minutes ago, bubba hotep said:

12z GFS looks like it keeps DFW below 40 for the high next Thursday. It is a ways off but there is growing agreement across operational and ensemble models that DFW could see the coldest air in years with this shot.

That seems almost certain at lease since March '14. A ~1050mb high over the Plains will be very nice with a cold W Canada. NW of where the surface low tracks will see some heavy wintery precip it looks. Hopefully the low trends south as is typical at this range.