Texas winter wx thread#5 - big changes on the way eventually

[Extremeweatherguy]

Is it just me, or is the NWS majorly underplaying the potential of this event?

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
243 PM CST TUE JAN 9 2007

.DISCUSSION...
CIRRUS CONTINUING TO STREAM ACROSS FROM THE W/SW...AND
IR/VIS LOOPS INDICATE THIS WILL CONTINUE OVERNIGHT AND
INTO TOMORROW. SECONDARY CF MAINTAINING THE DRY AND
COOL AIRMASS OVER THE REGION. SOME CAA WILL BE
OCCURRING OVERNIGHT WITH NE WINDS...HOWEVER THE NE WIND
WILL LIKELY KEEP MIN TEMPS FROM REACHING THE DW PTS.
THEREFORE...ONLY AREA THAT MAY FREEZE TONIGHT WILL BE
THE EXTREME NE ZONES.

MADE SOME ADJUSTMENTS TO THE ONGOING FORECAST...MAINLY TO THE
SUN AND BEYOND PD. THE BIGGEST CHG IS TO LOWER THE POPS TO
SLIGHT CHC MON AND TUE. THE LATEST (12Z) GFS INDICATES LESS
MOISTURE WILL BE AVAILABLE BEHIND THE FRONT THAN EARLIER
RUNS...AND THEREFORE ALSO LESS OF A POSSIBILITY FOR PRECIP.
HOWEVER...I COMPROMISED SOME WITH THE PREVIOUS FORECAST
TO LEAVE A SLIGHT CHC IN THERE...AS WE COULD SEE THE GFS
SWITCH BACK TO A WETTER SOLN. THIS IS IMPORTANT BECAUSE
OVERNIGHT TEMPS ON SUN...MON AND TUE WILL MOST LIKELY BE
NEAR OR SLIGHTLY BELOW FREEZING ACROSS NORTHERN AREAS...
AND POSSIBLY ACROSS CENTRAL AREAS MON AND TUES NIGHT.
DURING THESE PERIODS WILL HAVE A SLIGHT CHC OF MIXED PRECIP TYPE.
TEMPS WILL FALL QUICKLY ON SUN AS THE STRONG CF MOVES ACROSS SE TX.
AND MAY SEE FREEZING TEMPS REACH THE EXT N/NW ON SUN NIGHT.

GIVEN THAT THE AIRMASS IS OF ARCTIC ORIGIN...THERE IS STILL A
LOT OF UNCERTAINTY CONCERNING THE TEMPS/POPS EARLY NEXT WEEK.
MODEL GUIDANCE IS OFTEN ERRATIC WITH ARCTIC FRONTS DUE TO THE
SHALLOWNESS OF THE COLD AIR.

Seems like they are basically putting most of their trust into one run of the GFS model. At least they leave room for error by saying there is still a lot of uncertainty though.

If wxman57 and jeff are right, then this NWS forecast has huge bust potential.

[vbhoutex]

EWG, I think you are right on the fact that they are basing that forecast on the apparently faulty latest run of the GFS. I see too many different sources saying the same thing as Jeff and Chris to not agree more with their forecast than that one. Not sure who is running the Hou/Gal NWS but whoever wrote that discussion is overlooking the known problems with the GFS. Even most good amatuers know about the problems the GFS has with cold air like this. I am not putting down the NWS, but I have to agree on the bust potential for that forecast.

If I did anyting I would blend NWS and the others and probably be closer to the final outcome. Anyway you look at it, Saturday through most of next week will turnout to be a very interesting time weatherwise in TX IMO.

[Yankeegirl]

Who has a generator? Cause the party is going to be at your place if this storm verifies!! Ill bring the margaritas!!!

[GeneratorPower]

I've got 150 generators right now. :-0

[gboudx]

San Angelo seems to base their afternoon AFD on the 12z GFS as well. Don't bother reading it if you discount that model run.

[HouTXmetro]

Magarita's? It's going to be cold!!! How about some more Nog whith a shot of whiskey!

[Yankeegirl]

Sure, and how bout some hot chocolate with some mauibu? and Mr. generator, how bout you send one of those generators here to my house so I can have a party? You can come too!!!

[wxman57]

Is it just me, or is the NWS majorly underplaying the potential of this event?

Seems like they are basically putting most of their trust into one run of the GFS model. At least they leave room for error by saying there is still a lot of uncertainty though.

If wxman57 and jeff are right, then this NWS forecast has huge bust potential.

It's a rare case when the NWS isn't tricked by the MRF/GFS failures in the medium range. You never know who's making the forecasts, and you don't know the constraints they're under. For example, to go against the GFS and then have the GFS be wrong may turn out much better for the forecaster than the other way around. They are not encouraged to differ from model guidance as far as I can see. And by model guidance at this range, it's the GFS. Thinking for yourself is discouraged in government agencies.

[gboudx]

HWO from DFW.

HAZARDOUS WEATHER OUTLOOK FOR NORTH TEXAS
NATIONAL WEATHER SERVICE FORT WORTH TX
310 PM CST TUE JAN 9 2007


THERE IS A SLIGHT CHANCE OF LIGHT FREEZING RAIN FROM SATURDAY NIGHT
THROUGH ABOUT SUNSET SUNDAY....MAINLY WEST OF A BONHAM...DALLAS...
GOLDTHWAITE LINE. THIS THREAT HAS DIMINISHED A BIT IN THE PAST 24
HOURS. ANY PRECIPITATION AMOUNTS ARE EXPECTED TO BE LIGHT...
ALTHOUGH PATCHY ICE COULD BECOME A HAZARD FOR TRAVELERS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED THROUGH TONIGHT.

[HarlequinBoy]

This was an excerpt from the Tulsa AFD that I think applies quite well.

______
TEMPERATURES AND THUS PRECIPITATION TYPES REMAIN THE MAJOR PROBLEM
AND WILL MAKE OR BREAK WHAT TYPE AND HOW SEVERE THIS EVENT WILL BE.
EXISTING MODELS HISTORICALLY DO NOT PERFORM WELL OR CONSISTENTLY IN
THE SITUATION OF A SHALLOW DENSE CONTINENTAL POLAR TYPE AIR MASS.
HOWEVER... THIS EVENT IS SIMILAR TO OCCURRENCES IN THE PAST.
THEREFORE HAVE GONE BEYOND THE MODELS AND TAPPED INTO MANY YEARS OF
EMPLOYEE PERSONAL EXPERIENCE WITHIN THE TSA FORECAST OFFICE TO
ARRIVE AT THE CURRENT FORECAST.
______

______
OUR CURRENT THINKING REMAINS THAT THE ARCTIC AIR WILL CONTINUE TO
CHARGE SOUTHWARD THROUGH THE PLAINS RIGHT ON THROUGH THE FORECAST
AREA... AND NOT STALL OR BACK UP AS SOME MODELS DEPICT. WITH THAT IN
MIND... HAVE NOT RAISED SURFACE TEMPS IN OUR GRIDS POST FROPA AS
SOME MODELS WOULD SUGGEST. IN FACT... THE STALLING OR NORTHWARD
MOVING WARM AIR BEHIND THE SURFACE FRONT DEPICTED IN THE GFS AND
OTHER MODELS MAY BE ABOVE THE LAYER OF ARCTIC AIR AT THE SURFACE...
THUS SETTING THE STAGE FOR SUSTAINED PRECIPITATION INTO FREEZING
AIR.
______

[HouTXmetro]

I guess the train of thought on this board is the outlier. LOL

[TrekkerCC]

Is it just me, or is the NWS majorly underplaying the potential of this event?

Seems like they are basically putting most of their trust into one run of the GFS model. At least they leave room for error by saying there is still a lot of uncertainty though.

If wxman57 and jeff are right, then this NWS forecast has huge bust potential.

It's a rare case when the NWS isn't tricked by the MRF/GFS failures in themedium range. You never know who's making the forecasts, and you don't know the constraints they're under. For example, to go against the GFS and then have the GFS be wrong may turn out much better for the forecaster than the other way around. They are not encouraged to differ from model guidance as far as I can see. And by model guidance at this range, it's the GFS. Thinking for yourself is discouraged in government agencies.

I want to ask the pro mets this question. Looking at the GFS ensembles, it seems to indicate some members showing the precipitation on Tuesday. While it not overwhelming support in the ensembles(and some show the precipitation in various locations, i.e.: the gulf), it seems like a possibility that we could have some winter-type mix on Tuesday.

Relevant charts:

http://www.meteo.psu.edu/~gadomski/ENSPRS_0z/f180.html

http://www.meteo.psu.edu/~gadomski/ENSPRS_0z/f192.html

Do the NWS forecasters ever look at the ensemble members?

Apparently, they do:

THIS SUGGESTS THAT SOME
OF THE ENSEMBLE MEMBERS ARE INDICATING A MORE SIGNIFICANT AREAL COVERAGE OF FREEZING RAIN SUNDAY. FOR NOW...WE DO NOT EXPECT ANY MAJOR ICING...BUT IT DOES NOT TAKE MUCH TO CAUSE TRAVEL PROBLEMS.

[gboudx]

Delete. CaptainCrunch posted pretty much the same thing.

[CaptinCrunch]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
334 PM CST TUE JAN 9 2007

.DISCUSSION...
SURFACE RIDGE OF HIGH PRESSURE NOW EXTENDING INTO NORTH TEXAS THIS
AFTERNOON WITH RATHER PLEASANT WEATHER ACROSS THE AREA. SOME
HIGH CLOUDS WILL ENTER THE REGION THIS EVENING...AND WILL SLIGHTLY
INHIBIT RADIATIONAL COOLING...BUT OTHERWISE A COOL NIGHT IS
EXPECTED. WINDS WILL QUICKLY REVERSE AND BECOME SOUTHERLY BY
SUNRISE...AND INCREASE TO 15 TO 25 MPH BY AFTERNOON. THIS IS IN
RESPONSE TO A DEEPENING TROUGH ALONG THE WEST COAST WHICH WILL
BRING A CHANCE OF RAIN TO THE AREA BY THE END OF THE WORK WEEK AND
PUSH AN ARCTIC FRONT THROUGH SATURDAY EVENING.

AHEAD OF THE FRONT...A GRADUAL RETURN OF MOISTURE IS EXPECTED WITH
INCREASING CLOUDS WEDNESDAY NIGHT AND THURSDAY. CONTINUED WINDY
CONDITIONS AND CLOUDY SKIES WILL MAKE FOR MUCH WARMER LOW TEMPS
WITH SOME SHOWERS POSSIBLE BY THURSDAY NIGHT. THE MAIN CHANCES OF
RAIN WILL HOLD OFF UNTIL FRIDAY AND SATURDAY WHEN LARGE SCALE
FORCING AND DEEP MOISTURE WILL ALLOW FOR AN ERODING CAP AND
SCATTERED CONVECTION. THE COLD FRONT IS EXPECTED TO GRADUALLY SLIP
INTO THE NW CWA ON SATURDAY MORNING AND MAY STALL IN THE NORTHERN
CWA UNTIL MAIN PUSH ARRIVES SATURDAY EVENING.

COMPUTER MODELS CONTINUING TO OFFER VARYING SOLUTIONS ON THE
FRONTAL TIMING AND STRENGTH...WHICH CERTAINLY COMPLICATES THIS
FORECAST. VERY COLD AIR IS BEGINNING TO MOVE SOUTH AND WILL BE
POSITIONED ACROSS THE PLAINS BY FRIDAY. ARCTIC AIR OFTEN HAS A
TENDENCY TO ADVANCE FURTHER SOUTH THAN MODELS FORECAST...AND THIS
WILL HAVE TO BE WATCHED CLOSELY. ALL THE MODELS HAVE BECOME MORE
PROGRESSIVE WITH THE UPPER LEVEL TROUGH...WHICH WOULD LESSEN THE
CHANCES OF WINTER PRECIPITATION SUNDAY THROUGH TUESDAY. AT THIS
TIME...THERE STILL IS THE POTENTIAL...PARTICULARLY IN THE NW CWA
SUNDAY...FOR SOME LIGHT FREEZING RAIN BEFORE THE PRECIP SHUTS OFF.
THE TEMPERATURE FORECAST SATURDAY NIGHT AND SUNDAY IS OF LOW
CONFIDENCE...AND HIGHLY DEPENDENT ON WHEN THE FRONT COMES THROUGH.
HAVE USED THE 12Z GFS ENSEMBLE MEAN FOR THE TEMPERATURE FORECAST
WHICH IS IN LINE WITH PREVIOUS FORECASTS. THIS SUGGESTS THAT SOME
OF THE ENSEMBLE MEMBERS ARE INDICATING A MORE SIGNIFICANT AREAL
COVERAGE OF FREEZING RAIN SUNDAY. FOR NOW...WE DO NOT EXPECT ANY
MAJOR ICING...BUT IT DOES NOT TAKE MUCH TO CAUSE TRAVEL PROBLEMS.

THE COLD AIR WILL BE HERE TO STAY WITH TEMPERATURES SUNDAY THROUGH
TUESDAY CONSIDERABLY BELOW NORMAL. HIGHS IN THE 30S WITH LOWS IN
THE 20S WILL CONTINUE INTO EARLY NEXT WEEK. A LARGE SCALE TROUGH
WILL REMAIN OVER THE HEART OF THE COUNTRY...AND CONTINUED
REINFORCEMENT OF THE ARCTIC AIR IS EXPECTED. WE WILL HAVE TO WATCH
FOR POSSIBLE LIGHT FREEZING PRECIP TOWARD THE MIDDLE OF NEXT
WEEK...BUT FOR NOW HAVE KEPT ALL BUT THE SOUTHERN CWA PRECIP FREE
MON-TUE.

[CaptinCrunch]

Well after reading much of the main NWS AFD's no one really has a clue to what's going to take place by Saturday. Just about all AFD's are now holding back on wintery precip except for Amarillo which keeps some form of frozen precip in the forecast. Looks like the wild card continues to be the shallow arctic at the surface and wheather models are picking it up or not. Like most have said, models just don't see the shallow dence air at the surface, so this jacks up the forecast. (as Homer Simpson would say "stupid shallow air"

Either way all AFD's agree on one thing, it's going to get COLD and it will be sticking around thru mid next week. Now if we can just get next system in here in that time frame then maybe we ALL can get a little wintery precip.

[GeneratorPower]

WINTERICAL WEATHER OUTLOOK
NWS WWPC/NATIONAL ICECANE CENTER FORT WORTH TX
530 PM EDT TUE JAN 09 2007

FOR THE NORTH TEXAS AREA...DALLAS...AND THE GULF OF MEXICO MOISTURE SUPPLY...

A WINTER WAVE APPROACHING THE CANADIAN BORDER IS GENERATING
DISCUSSION AND GIVING THE GFS THE RUNS. THIS ACTIVITY WILL SPREAD EASTWARD
THROUGH THE UNITED STATES OVER THE NEXT COUPLE OF DAYS. WHILE
THE SYSTEM HAS BECOME A LITTLE BETTER UNDERSTOOD THIS AFTERNOON...
ADDITIONAL DEVELOPMENT...IF ANY...IS EXPECTED TO BE SLOW TO OCCUR.

ELSEWHERE...WINTER STORM FORMATION IS NOT EXPECTED THROUGH
THURSDAY.

$$
FORECASTER GOOF/BALL

[gboudx]

heh

[cctxhurricanewatcher]

edited

[cctxhurricanewatcher]

WINTERICAL WEATHER OUTLOOK
NWS WWPC/NATIONAL ICECANE CENTER FORT WORTH TX
530 PM EDT TUE JAN 09 2007

FOR THE NORTH TEXAS AREA...DALLAS...AND THE GULF OF MEXICO MOISTURE SUPPLY...

A WINTER WAVE APPROACHING THE CANADIAN BORDER IS GENERATING
DISCUSSION AND GIVING THE GFS THE RUNS. THIS ACTIVITY WILL SPREAD EASTWARD
THROUGH THE UNITED STATES OVER THE NEXT COUPLE OF DAYS. WHILE
THE SYSTEM HAS BECOME A LITTLE BETTER UNDERSTOOD THIS AFTERNOON...
ADDITIONAL DEVELOPMENT...IF ANY...IS EXPECTED TO BE SLOW TO OCCUR.

ELSEWHERE...WINTER STORM FORMATION IS NOT EXPECTED THROUGH
THURSDAY.

$$
FORECASTER GOOF/BALL

[Portastorm]

I'm a little confused by NWSFO Fort Worth's comment "all of the models have become progressive with the upper trough."

Which models? All of the GFS runs? Wxman57 already pointed out earlier than the Euro is NOT all that progressive with the trough.

I'm sticking with my football. I'm going to kick that darn thing and unless Tony Romo (sorry Cowboy fans!) is my holder, I feel confident ... THIS TIME ... it'll happen.