Texas winter wx thread (2009-2010)

[Ntxw]

Oz gfs at 66h

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_pcp_066s.gif

[iorange55]

Oz gfs at 66h

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_pcp_066s.gif

Light snow is better than no snow. I'm not really trusting any model though I think it's just one of those wait till that day things. Might snow a lot, might not snow at all.



New GFS is looking colder for this week though.

[serenata09]

Dallas WFAA met just said DFW might even see "a touch of snow."

[HockeyTx82]

Dallas WFAA met just said DFW might even see "a touch of snow."

Who was it? Delkus or McCauley. McCauley is fun to watch. He has no problem of showing what could happen when it may not happen. I guess he likes to keep things interesting. I have no problem with it, I am glad to see a local met who likes his job. Plus I am sure it makes ratings and gets people watching. Last winter he was the only local met I knew of that actually talked about the McFarland Signature that was going to form and ended up going NE of us. It was cool to see and got people talking.

[joshskeety]

The problem is not with the upper level temps.. If I went with 850mb temps, here in Abilene we would have 10-12 inches of snow with the latest GFs.. can it happen? Sure.. But Surface temps have to support it.. Right now surface temps are showing 34-35 degrees.. what is throwing everyone off is the fact that the ECMWF has wetbulbs lower then expected and dewpoints lower, but the GFS and NAM refuse to bring temps down..

Im sure inside the doors here at SJT they are saying this could explode, but in public discussions they are going to be conservative.. Nobody wants to be the guy to call for a snowstorm in Texas that doesn't happen.. Impacting economy and other things just because you jumped the gun..

They have time to let things play out, and they will use every ounce of that time, however, the more into the time, the more the GFS is going colder and colder and the NAM as well.. The ECMWF under 48 hours with ULL's becomes pretty useless..

Right now I feel that with the Wetbulbs and Dewpoints being in the mid to upper 20's and lower 30's in the DFW area, everyone will see snow.. Probably heavy snow.. Now weather its cold enough to stick?? Remember, it was 70 degrees yesterday, ground temps are warm as it is..

I feel anyone west of Mineral Wells sees sticking snow.. I think anyone west of Eastland/Cisco to Brownwood gets some significant accumalations.. I don't see a major issue in DFW at this point, but again, the difference between 35 degrees and 32 degrees is just 3 degrees..

I will say this.. Easter 1996 was this exact same set up.. DFW only got rain, but temps were progged warmer than these. Nobody was supposed to see snow outside of far west Texas.. The Cut off ULL 500 low came from California and the temp dropped MUCH colder than the models showed.. Granted, that was 1996 technology...

Just going to be fun to watch...

[serenata09]

Dallas WFAA met just said DFW might even see "a touch of snow."

Who was it? Delkus or McCauley. McCauley is fun to watch. He has no problem of showing what could happen when it may not happen. I guess he likes to keep things interesting. I have no problem with it, I am glad to see a local met who likes his job. Plus I am sure it makes ratings and gets people watching. Last winter he was the only local met I knew of that actually talked about the McFarland Signature that was going to form and ended up going NE of us. It was cool to see and got people talking.

It was McCauley.

[Ntxw]

Not to mention a cold front coming down on the backside\around the same time frame of this low, I wonder how that would play a role.

[HockeyTx82]

Dallas WFAA met just said DFW might even see "a touch of snow."

Who was it? Delkus or McCauley. McCauley is fun to watch. He has no problem of showing what could happen when it may not happen. I guess he likes to keep things interesting. I have no problem with it, I am glad to see a local met who likes his job. Plus I am sure it makes ratings and gets people watching. Last winter he was the only local met I knew of that actually talked about the McFarland Signature that was going to form and ended up going NE of us. It was cool to see and got people talking.

It was McCauley.

DFW NBC 5 met just said Wednesday morning possible rain/snow mix N&W of Fort Worth. He seemed pretty certain that there will be no accum and no ice. Hmmmmm........

[iorange55]

The gfs 06 is trying to come more in line with the NAM.



HMMMMM.


NWS however has taken snow out of the forecast for even Stephenville. Bummer.



EDIT: Part of the Dallas NWS discussion

THE UPPER LEVEL LOW WILL FINALLY LUMBER ACROSS NORTH TEXAS
WEDNESDAY MORNING. MODELS CONTINUE TO SHOW THICKNESS VALUES COLD
ENOUGH FOR SNOW IN THE CORE AND NORTHERN SIDE OF THE UPPER LEVEL
LOW. HOWEVER...CLOSER INSPECTION SHOWS SURFACE TEMPS /AND WET
BULBS/ WILL BE SEVERAL DEGREES ABOVE FREEZING TUESDAY NIGHT AHEAD
OF THE LOW. THERE IS NO SHORTAGE OF COLD AIR IN THE MID-UPPER
LEVELS FOR SNOW...THE INHIBITING FACTOR IS THE WARM LOW LEVEL
TEMPS. SINCE THERE WILL BE LITTLE WET BULB COOLING OR COLD
ADVECTION TUESDAY NIGHT...THE ONLY MECHANISM LEFT TO FORCE LOW
LEVEL TEMPS COLDER IS LATENT HEAT ABSORPTION CAUSED BY THE MELTING
OF FALLING SNOW. TYPICALLY THIS REQUIRES A FAIRLY LARGE AMOUNT OF
MELTING SNOW...AND THUS ONLY OCCURS IN HEAVY PRECIPITATION AREAS.
SIGNIFICANT CLOUD LEVEL SNOW IS EXPECTED TO OCCUR MAINLY ON THE
BACKSIDE OR NW SIDE OF THE UPPER LEVEL LOW...WHICH SUGGESTS THE
WESTERN AND NORTHWESTERN ZONES OF NORTH TEXAS WILL HAVE THE BEST
CHANCES OF SEEING ANY SNOW REACH THE GROUND LATE TUESDAY NIGHT AND
WEDNESDAY MORNING. EVEN IF SNOW DOES REACH THE GROUND IN THESE
LOCATIONS...SIGNIFICANT ACCUMULATIONS ARE NOT EXPECTED.

If i remember correctly that wet bulb is really tricking, and I remember them thinking before in past years the wet bulb would be cold enough for snow, and it never cooled enough. It looks like one of those you don't know till its falling things, to me at least. I'm not expecting snow, but I wouldn't be surprised if it fell.

[Portastorm]

Interesting little snippet from Larry Cosgrove's posted forecast last evening. He's referring to the week of Dec. 7-11:

If I believe the GGEM and ECMWF ensemble packages (and, with its prominent thumb projection block into Alaska, I do....), we will see record cold temperatures for at least part of next week.

[wxman22]

Larry Cosgrove from the Houston Weather Examiner thinks there may be snow in Houston Wednesday morning...

Wednesday: Cloudy, windy and unseasonably cold with showers. Some sleet and/or flurries could occur north of Interstate 10. Highs 41 Navasota to 45 Bayou Vista

http://www.examiner.com/x-3775-Houston- ... er-30-2009

[Ntxw]

06z NAM at 60h

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/06/images/nam_pcp_060s.gif

[Portastorm]

Well snow or no snow, it feels wintry in AUS this morning. We have steady rain and 45 degrees with a decent north breeze. Big difference from the 70s we had this past weekend!

[srainhoutx]

48.5 and cold in NW Harris County. Brrr.... Now we wait and see what the Upper Low will offer.

[srainhoutx]

I'll add the HPC Prelim Extended Range Disco as it gives some "hints" as to what we may be looking at in the longer range...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
737 AM EST MON NOV 30 2009

VALID 12Z FRI DEC 04 2009 - 12Z MON DEC 07 2009


MODEL AND ENSEMBLE GUIDANCE ALL SHOW PRONOUNCED AMPLIFICATION OF
THE NORTHEAST PACIFIC DEEP LAYER RIDGE. THIS LEADS TO A
DOWNSTREAM DEVELOPMENT OF A WESTERN US TROUGH AND THE DEVELOPMENT
OF A SFC ANTICYCLONE IN WESTERN CANADA AS A DOME OF COLD AIR
BUILDS IN WESTERN CANADA AND STARTS MOVING INTO THE NORTHWESTERN
US. THE PRELIMINARY FRONTS AND PRESSURES ARE PRIMARILY A BLEND OF
THE NCEP AND ECMWF ENSEMBLE MEANS...WITH MINORITY CONTRIBUTIONS OF
THE 00Z ECMWF/CANADIAN/UKMET SOLUTIONS.

THE MODELS ARE IN GOOD AGREEMENT ON THE EASTERN US CYCLONE DAYS
3-4 AS IT MOVES NORTH ACROSS NY/NEW ENGLAND AND UP INTO CANADA.
THE 06Z GFS HAS SLOWED DOWN TO MATCH THE TIMING OF THE
ECMWF/CANADIAN/UKMET/RESPECTIVE ECMWF/NCEP ENSEMBLE MEAN. WITH
GOOD CLUSTERING OF SOLUTIONS...A BLEND OF THE MODELS WAS USED.

THE DIFFERENCES START TO DEVELOP UPSTREAM OFF THE WEST COAST.
PHASING DIFFERENCES AMONG MODEL/ENSEMBLE SOLUTIONS LEADS TO LARGE
SPREAD OF POSSIBLE SCENARIOS. WITH INITIAL ENERGY PROGRESSING
FROM THE EASTERN PACIFIC INTO NORTHWEST US... THE 00Z GFS WAS ON
THE FAST EDGE OF GUIDANCE AND WAS NOT USED AS THE 06Z GFS HAS
SLOWED TOWARDS THE TOWARD THE CONSENSUS CLUSTER. IN ADDITION TO
TIMING DIFFERENCES...THE ECMWF HAS FORMED A DEEPER CLOSED LOW
SFC/ALOFT ON THE WESTERN EDGE OF THE GUIDANCE ENVELOPE THAN THE
GFS/CANADIAN/UKMET/EARLIER ECMWF RUNS AND THE ECMWF ENSEMBLE MEAN.
7 OF THE 50 ECMWF ENSEMBLE MEMBERS HAVE A CLOSED 500 MB LOW LIKE
THE OPERATIONAL ECMWF...WITH WIDE DISPERSION ACROSS THE NORTHEAST
PACIFIC FRIDAY AND THEN ONSHORE SATURDAY. A MULTI-MODEL AND
ECMWF/NCEP ENSEMBLE MEAN CONSENSUS WAS USED TO MITIGATE THE
DIFFERENCES.

MULTI-DAY MEANS SUGGEST THE CORE OF POSITIVE HGT ANOMALIES
UPSTREAM SHOULD BE OVER THE GULF OF AK TO THE SOUTHERN AK
COASTLINE... WHICH TELECONNECTS TO A MEAN TROF EXTENDING SOUTHWEST
FROM HUDSON BAY ACROSS THE NORTHERN HIGH PLAINS/ROCKIES INTO THE
GREAT BASIN. THIS IN TURN SUPPORTS COLDER THAN NORMAL TEMPS IN
THE NORTHWEST US TO THE NORTHERN PLAINS AND EVENTUALLY UPPER MS
VALLEY. CONVERSELY...THIS PATTERN FAVORS THE DEVELOPMENT OF WARMER
THAN NORMAL TEMPS ACROSS THE SOUTHEAST/FL ON DAY SEVEN AND BEYOND.

THE CANADIAN/UKMET AND SEVERAL NCEP/ECMWF ENSEMBLE MEMBERS SHOW
THE DEVELOPMENT OF A NORTHWEST US CLOSED 500 MB LOW SAT...AND THE
06Z GFS BY SUN. THE CANADIAN MODEL BECOMES THE SOUTHERN OUTLIER
ON SUN DEC 06 AND MON DEC 07. ON DAYS 4-5...THE CANADIAN IS
INCLUDED WITH THE UKMET AND ENSEMBLE MEANS IN SHOWING DEVELOPMENT
OF THE NORTHWEST US TROUGH. ON DAY 7...THE CANADIAN WAS
DISCONTINUED IN FAVOR OF GREATER WEIGHTING OF THE MEANS.

PETERSEN/RAUSCH

[Portastorm]

Hmmm ... strong ridging developing in Alaska and extending south along the west coast of Canada .... troughing developing from Hudson Bay down into the Plains and a ridge poking up in the SE US ... I'd say that was a cold and stormy recipe for the southern Plains and Texas!

Am I wrong?

[snow and ice]

My call for this week and beyond. Based on the latest model runs and past experience, I think an area north of a Mount Pleasant-Shreveport-El Dorado,Arkansas line will get 2-4 inches of snow. That is a lot of snow considering temps will be at or just above freezing during the precip and the warm ground. I think the snow will be heavy enough to overcome those obstacles as I've seen it happen before.

The end of the week will turn surprisingly cold, probably 10 or so degrees below normal. Next week, strong cross polar develops with a zonal flow over the lower 48. However, the dense-shallow arctic air will under cut the upper flow and make it all the way to the GOM. There will be much debate next week among NWS offices as to how far south the arctic air will trek into the lower 48. Get ready for a lot forecast bust next week as the GFS will not handle the southward progression of the arctic air.

BTW, this is a lot different set up from last years' arctic blunder. The upper flow in the northern latitudes will be more north-south, not NW-SE like last year. And, most importantly, temperatures in Western Canada, Montana, and Wyoming will not be in the 60's and 70's. I kept pointing that out on another board last year, and people were still saying the arctic air would come down the lee of the Rockies,with record cold in Texas. Amazingly, some of them were pro meteorologist. If it's warm a long the lee of the Rockies from Colorado into Canada, it's not going to get cold in Texas.

[srainhoutx]

My call for this week and beyond. Based on the latest model runs and past experience, I think an area north of a Mount Pleasant-Shreveport-El Dorado,Arkansas line will get 2-4 inches of snow. That is a lot of snow considering temps will be at or just above freezing during the precip and the warm ground. I think the snow will be heavy enough to overcome those obstacles as I've seen it happen before.

The end of the week will turn surprisingly cold, probably 10 or so degrees below normal. Next week, strong cross polar develops with a zonal flow over the lower 48. However, the dense-shallow arctic air will under cut the upper flow and make it all the way to the GOM. There will be much debate next week among NWS offices as to how far south the arctic air will trek into the lower 48. Get ready for a lot forecast bust next week as the GFS will not handle the southward progression of the arctic air.

BTW, this is a lot different set up from last years' arctic blunder. The upper flow in the northern latitudes will be more north-south, not NW-SE like last year. And, most importantly, temperatures in Western Canada, Montana, and Wyoming will not be in the 60's and 70's. I kept pointing that out on another board last year, and people were still saying the arctic air would come down the lee of the Rockies,with record cold in Texas. Amazingly, some of them were pro meteorologist. If it's warm a long the lee of the Rockies from Colorado into Canada, it's not going to get cold in Texas.

How well I remember What a debate, no? I agree that this is not at all like last year. Your analysis is spot on IMHO.

[joshskeety]

All 3 major models GFS/NAM/and ECMWF are now showing significant snowfall west of a Wichita Falls/Eastland/Brownwood line..

All 3 models are also saying that wrap around moisture could impact the area until Thursday morning..

All 3 models are also saying that the DFW area could see 1-3 inches of snow... Dewpoint are in the lower 30's for the DFW area on Wednesday, despite what the NWS is trying to say..

In other words, we are NOT stupid.. If its 1 in the afternoon and your Dewpoint is 31 degrees and the Humidity is 100%, please don't tell me that the model is suggesting a high in the Middle 40's...

Sheesh..

[Portastorm]

All 3 major models GFS/NAM/and ECMWF are now showing significant snowfall west of a Wichita Falls/Eastland/Brownwood line..

All 3 models are also saying that wrap around moisture could impact the area until Thursday morning..

All 3 models are also saying that the DFW area could see 1-3 inches of snow... Dewpoint are in the lower 30's for the DFW area on Wednesday, despite what the NWS is trying to say..

In other words, we are NOT stupid.. If its 1 in the afternoon and your Dewpoint is 31 degrees and the Humidity is 100%, please don't tell me that the model is suggesting a high in the Middle 40's...

Sheesh..

As we have talked about for years here on S2K, some NWSFOs in Texas are better than others when it comes to forecasting winter weather events. Some forecasters are dedicated to the grids and strictly following GFS MOS. Others are not.

I would expect more forecast changes today from NWSFO Fort Worth. They're probably feeling quite challenged by this event and they should be ... upper-low events in Texas during the winter can be very challenging!