Texas Winter 2014-2015

[srainhoutx]

late Sunday evening briefing from Jeff:


Frequent weather changes coming to TX over the next several days.

 

Initial storm system moving into the central plains this evening with a trailing line of thunderstorms into N TX and scattered showers in the warm air advection regime over SE TX. Main dynamics are well north of the region and the surface cold front is well west of the area over W TX. Dry air is noted above the surface helping to keep rain showers scattered and light. Will likely see a slight increase in shower activity as the cool front crosses the area tomorrow afternoon. Post frontal air mass is Pacific in nature so only a slight cool down…or back to near average from the  above average warmth of late.

 

Tuesday will by partly cloudy and cool with lows in the 40’s and highs in the 60’s (near normal).  

 

Southern stream jet will remain very active with next upstream storm system rapidly approaching from the west by mid to late week. Surface front over the NW Gulf will bring to return northward as a warm front on Wednesday. Expect warm air to overrun the cool surface dome by late Tuesday with clouds increasing from SW to NE late Tuesday and light rain and fog developing north of the warm front on Wednesday. Models are usually too fast in their northward transport of the warm air mass in such situations and think this will be no different with the front slowly moving inland late Wednesday.

 

Region is warm sectored Thursday and Friday as strong storm system approaches from the WSW out of NE MX on Friday. Expect increasing chances for showers and thunderstorms Thursday with the best chances arriving on Friday. Could see some heavy rainfall Thursday and Friday with good moisture advection. Instability looks limited, so not expecting any severe weather. Temperatures will run above normal again Thursday and Friday with lows in the 60’s and highs in the 70’s. Post frontal air mass behind this storm will be of more Canadian air with temperatures falling into the 30’s and 40’s for lows and 50’s for highs by next weekend. GFS suggest low level moisture may be trapped in the frontal inversion next weekend and this would result in a cold air advection low level stratus deck and keep highs even colder than currently suggested.

 

Christmas Week:

Third storm system appears to arrive 22-24 Dec with another shot for showers and thunderstorms. This storm system however appears to help buckle the upper air pattern with ridging building deep into Alaska and a large downstream trough carving out across much of the US. Bitter cold air mass currently in place over Siberia (-40 to -50F) may shift across the north pole and into NW Canada as the ridge builds into Alaska. This would place extremely cold Siberian air in place to be unleashed southward into the US following the early Christmas week storm system. Forecast models have been hinting at enough upper air pattern amplification during the period between Christmas and New Year’s to suggest at least some arctic air could be in store for the area. Additionally, the southern stream will remain active with storm systems roughly every 2-4 days across TX. While this pattern change is still over 7 days away, operational and ensemble support has been increasing over the last few days and much colder and stormy pattern appears increasingly likely by Christmas week and into early 2015. Main questions over the next several days will be if the coldest air comes straight southward or glances TX and heads more for the east coast and if enough cold air will be in place with any of the storm system to produce any winter precipitation.

[ronyan]

Great update from Jeff as usual.

0z GFS shows shows ~10C 2m temp anomalies in SE TX on Dec 27th +300 hrs with cold air covering 90% of the country including West of the Rockies (only FL panhandle excluded but the front makes it through there eventually). The whole country ends up cold towards the latter part of the run.

This will be an interesting pattern change to watch, hopefully we get some moisture in on this if the arctic air comes down.

[Texas Snowman]

From Fort Worth NWS page today: "December 15-16, 1983 A narrow band of 4-6 inches of snow fell along a line from Weatherford to Denton to Greenville and Paris. Another band of 4-8 inches occurred from Wills Point to Tyler and Gilmer."

Also produced some snowfall here in the Red River Valley. I vividly remember having snowball fights after this storm in the parking lot at Denison High School during my senior year. What was ushered in next was the longest cold wave in modern Texas history.

[srainhoutx]

The global ensembles are suggesting an active pattern as multiple short waves embedded within fairly quick moving troughs off the Pacific traverse our Region into Christmas Eve. The next strong storm system arrives Wednesday into Friday bringing heavy mountain snow across New Mexico on Thursday and depending on the eventual track, heavy rainfall across portions of Texas into Louisiana. The 00Z OP Euro is the southern most tracking solution with the 5H closed low tracking across N Mexico, Del Rio and on E to Lufkin while the GFS suggests the upper low crossing NM, Childress and into NE Oklahoma on Friday. If the southern track were to verify, strong to possibly severe storms may be possible across Austin and Houston Friday. A more northern track would favor the Dallas/Shreveport area for stronger storms. This system has a bit more colder air to work with, so the dynamics appear a bit better for heavy rainfall.

An even stronger storm looks likely near Christmas Eve with even colder air in place as the pattern begins to transition. Being more than a week out it is too soon to speculate on the finer details with a wave currently over Eurasia heading E.

The longer range ensembles are in good agreement that a whole sale pattern change is ahead for the period between Christmas and New Years Day. It does appear we are transitioning to a +PDO/+PNA/-EPO/-AO and possibly a -NAO blocking pattern as we near the climatological favored coldest time of year for our Region as January 2015 begins.

[weatherdude1108]

Is the atmosphere finally responding to an El Nino pattern?


Hampshire:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
523 AM CST MON DEC 15 2014

.PREV DISCUSSION... /ISSUED 348 AM CST MON DEC 15 2014/

LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)...
BY WEDNESDAY...THE NEXT UPPER LEVEL TROUGH WILL BE ENTERING THE
SOUTHWESTERN CONUS WITH SOUTHWEST FLOW SET UP OVER TEXAS AHEAD OF
THIS SYSTEM. AS A RESULT...DEEP SOUTHERLY FLOW IN THE LOWER LEVELS
WILL RETURN TO THE REGION BY WEDNESDAY AFTERNOON. THIS SETUP IS
FAVORABLE FOR SHOWER DEVELOPMENT INDUCED BY THE WARM AIR ADVECTION
OR ISENTROPIC LIFT. WILL CONTINUE TO CARRY CHANCE POPS WEDNESDAY
AND WEDNESDAY NIGHT.

THURSDAY...THE UPPER TROUGH WILL BE NEARING THE REGION AND WE
SHOULD SEE ADDITIONAL ACTIVITY AS UPPER HEIGHT FALLS AND THE DEEP
FORCING ASSOCIATED WITH THE TROUGH APPROACHES THE AREA. MODELS
HAVE SOME DISCREPANCIES WITH THE STRENGTH AND TRACK OF THE UPPER
LOW THAT WILL HAVE A BEARING ON RAIN CHANCES AND AMOUNTS THURSDAY
NIGHT INTO FRIDAY AS THE LOW MOVES THROUGH THE SOUTHERN PLAINS.
THE GFS/CANADIAN KEEP THE TRACK MORE PROGRESSIVE WITH THE CENTER
OF THE LOW PASSING WELL NORTH OF THE CWA. THE ECMWF ON THE OTHER
HAND IS A BIT SLOWER AND DIGS THE TROUGH FARTHER SOUTH. THUS THERE
ARE FURTHER DIFFERENCES WITH THE REST OF THE MODEL OUTPUT. THE
ECMWF HAS THE SURFACE LOW TRACKING THROUGH THE CWA FRIDAY MORNING
AND AFTERNOON WITH HIGH AMOUNTS OF QPF. THE GFS HAS THE TRACK OF
THE SURFACE LOW WELL NORTH OF THE REGION. WILL SIDE WITH THE GFS
SOLUTION FOR THE MOST PART AS THERE IS AGREEMENT WITH THE
CANADIAN. ALSO...NO MEMBER OF THE GFSENSEMBLES SUPPORT THE
SOUTHERN TRACK OF THE ECMWF. THIS OUTCOME WOULD BE SIMILAR TO THE
CURRENT TROUGH AFFECTING THE REGION CURRENTLY. MODELS HAD A
SOUTHWARD TRACK BEFORE COMING INTO AN AGREEMENT WITH THE LOW
MOVING THROUGH OK/KS. NEVERTHELESS...THERE ARE CONTINUED CHANCES
OF RAIN LINGERING INTO FRIDAY...BUT WILL KEEP POPS AT OR BELOW 50
PERCENT FOR THE MOST PART. THE BEST CHANCES OF RAIN WILL BE IN THE
NORTHERN AND EASTERN ZONES. MODELS ARE SHOWING ABOUT 800 J/KG OF
SBCAPE ACROSS THE SOUTHERN ZONES THURSDAY NIGHT/FRIDAY AND WILL
MENTION THUNDER FOR THIS TIME PERIOD ACROSS THE SOUTH.

A COLD FRONT WILL MOVE IN BEHIND THIS SYSTEM...BRINGING COOLER AND
DRIER WEATHER TO THE AREA FOR THE WEEKEND. THE PROGRESSIVE PATTERN
WILL CONTINUE WITH YET ANOTHER LOW MOVING INTO THE AREA FOR THE
BEGINNING OF NEXT WEEK. THERE ARE A NUMBER OF DIFFERENCES WITH
THIS SYSTEM...BUT THERE IS A CHANCE FOR A BIT MORE PRECIP THAN THE
PREVIOUS COUPLE OF SYSTEMS AND COLDER WEATHER AS WELL.

HAMPSHIRE

[gatorcane]

Notice the 00Z ECMWF (and it's ensembles members, not shown) is replacing the warmer temperature anomalies across Southern Canada with colder anomalies in the long-range which is lining up with the long-range GFS forecasts from last week (which went beyond 240 hours where we couldn't see the ECMWF forecasts since it only goes out that far). So the pattern does look to be changing right around or just after Christmas based on the global model guidance trends. Still looking like significant cold air could intrude into the lower 48 starting around the end of this month

[Ntxw]

And now the AO is going to tank. Like clockwork, the teleconnections are lining up, much like in November during cold climo.

We already know the EPO will go negative. The risk for a deep freeze between Dec 28th through Jan 10th is increasing.

[cycloneye]

And now the AO is going to tank. Like clockwork, the teleconnections are lining up, much like in November during cold climo.

We already know the EPO will go negative. The risk for a deep freeze between Dec 28th through Jan 10th is increasing.

AO is going to literally crash.

[TarrantWx]

Does anyone have a link to EPO forecast? The site that I have been using doesn't seem to be working right. As others have already said the AO, PNA, and NAO look to be trending in our favor. One of the ensembles is even tanking the AO to 5 SD's below normal. I will be travelling to eastern Iowa for Christmas so I'm really curious to see what comes out of this Christmas storm. Would be great to experience a good Midwest blizzard and then come home to a Texas blizzard

[TheProfessor]

yeah I'm going to be traveling to Topeka Kansas next week, it would be pretty cool to get a snow storm there, and then come back home to a snowstorm.

[Ralph's Weather]

Seems like the models are really struggling to figure out the pattern change as is typical. I am expecting the first round of Arctic air to hit the weekend after Christmas, and after that we will see repeated chances for snow in Texas for an extended period.

[TeamPlayersBlue]

Im expecting to visit family in AZ early Jan. If we have winter precip here and i miss it, heads will roll! I actually will be gone for most of January so the chances of me missing it are increasing.


I saw a SSW event is forecast for around the 28th in Siberia as well. Things are really lining up.

[Ntxw]

Does anyone have a link to EPO forecast? The site that I have been using doesn't seem to be working right. As others have already said the AO, PNA, and NAO look to be trending in our favor. One of the ensembles is even tanking the AO to 5 SD's below normal. I will be travelling to eastern Iowa for Christmas so I'm really curious to see what comes out of this Christmas storm. Would be great to experience a good Midwest blizzard and then come home to a Texas blizzard

Most free sites don't show the EPO its unfortunate. A lot is subscribed, but fortunately its very easy to pick out. If you see heights rise and ridging poke into Alaska and/or NW Canada you very likely have a -EPO (refer to McFarland's paper, great work on the EPO signal). If the ridging sits and intensifies you have a -EPO tank. Not official but over the years I've noticed when you get height rises over 560dm in general it signals an arctic discharge forthcoming.

[aggiecutter]

From Fort Worth NWS page today: "December 15-16, 1983 A narrow band of 4-6 inches of snow fell along a line from Weatherford to Denton to Greenville and Paris. Another band of 4-8 inches occurred from Wills Point to Tyler and Gilmer."

Also produced some snowfall here in the Red River Valley. I vividly remember having snowball fights after this storm in the parking lot at Denison High School during my senior year. What was ushered in next was the longest cold wave in modern Texas history.

Texarkana got 8" out of that storm. The forecast was for a 30% chance of light snow. I got up at 5:00 that morning to get ready for work. When I went outside to get the paper, light snow was falling. I left for work at 6:00, and heavy snow was falling. By the time I got to work, the ground was already covered. The majority of the snow fell between 6-10 that morning. At an average of about 2" per hour, that was about the heaviest snow I have ever seen.

[gboudx]

I'll be reading all of y'all updates very intently this week and next. We're going to SELA for Christmas and coming back on the 29th. I don't have a problem with snow, but ice and sleet could make driving challenging. Keep up the great work guys!

[Portastorm]

I love me some 12z GFS today! Frozen precip in Austin on 12/30.

[gatorcane]

And now the AO is going to tank. Like clockwork, the teleconnections are lining up, much like in November during cold climo.

We already know the EPO will go negative. The risk for a deep freeze between Dec 28th through Jan 10th is increasing.

Indeed in fact the 12Z GFS and PGFS are both showing the large-scale pattern change across North America starting around days 8-10. The Euro even hinting also. Let's see what the 12Z Euro shows and whether it continues advertising the pattern shift.

[TheStormExpert]

And now the AO is going to tank. Like clockwork, the teleconnections are lining up, much like in November during cold climo.

We already know the EPO will go negative. The risk for a deep freeze between Dec 28th through Jan 10th is increasing.

Indeed in fact the 12Z GFS and PGFS are both showing the large-scale pattern change across North America starting around days 8-10. The Euro even hinting also. Let's see what the 12Z Euro shows and whether it continues advertising the pattern shift.

I know this is the Texas thread but how could this potentially influence Florida this time around?

Unlike in November when the NAO barely went negative and the cold arctic aired stayed well to the north this time there is the potential of having a negative NAO/AO, and positive (at least slightly) PNA.

[TeamPlayersBlue]

I love me some 12z GFS today! Frozen precip in Austin on 12/30.

SE Tx and East Texas get ROCKED by a snowstorm. I think its actually closer to almost a blizzard lol

Folks, we've been patient long enough, i think our time is coming.

[BigB0882]

Can you please post a graphic of the 12z GFS showing the winter weather? Curious if it makes it over to SELA. I will actually be in Beaumont on the 30th and travelling to Alexandria then Baton Rouge. I know it is way far off but if it comes to pass then holiday plans will need to be reworked and at least I can start thinking of the options in advance.