Texas Winter Weather Thread #3 - GFS showing cold christmas

[southerngale]

Highs in the 40's? Wasn't it showing highs in the 30's the other day?

jschlitz...I care. lol
I checked Accuweather's 15-day forecast last night, just to see. That was the first time I'd checked it since last year, I believe. I think I was looking for that snow icon then too. hehe

At least I won't be running my A/C on Christmas!!

The possible 30s was based on the fact that it also showed precip. falling that day. Now, the latest run brings in the precip. much sooner and exits it much sooner which may allow for a little Christmas day clearing..thus warmer high temperatures.

It all really depends on cloud cover, precip. and the exact amount of cold air in place. We should know more about the exact forecast in a few days.

Now that's the dream-squashing scenario I'm used to seeing!

[Extremeweatherguy]

Highs in the 40's? Wasn't it showing highs in the 30's the other day?

jschlitz...I care. lol
I checked Accuweather's 15-day forecast last night, just to see. That was the first time I'd checked it since last year, I believe. I think I was looking for that snow icon then too. hehe

At least I won't be running my A/C on Christmas!!

The possible 30s was based on the fact that it also showed precip. falling that day. Now, the latest run brings in the precip. much sooner and exits it much sooner which may allow for a little Christmas day clearing..thus warmer high temperatures.

It all really depends on cloud cover, precip. and the exact amount of cold air in place. We should know more about the exact forecast in a few days.

Now that's the dream-squashing scenario I'm used to seeing!

There should still be a decent shot of precip. on the 23rd and 24th though and winter weather still looks possible early on the 24th (there is also the chance of light snow showers on Christmas evening), so don't worry. There is still plenty of hope!

This is also a rapidly changing scenario too, so for all I know..the precip. could actually stick around longer. If it does, then we may all be in luck for some wintry weather.

At this point though, I think that there are still too many IF's for a "for-sure" forecast just yet.

[gboudx]

And the upper-low could track much further north than currently forecasted by the models. That's what happened a few weeks ago when DFW was expecting 2-4 inches of snow. The low tracked further north and we got a light dusting; a very light dusting.

[aggiecutter]

Brent, It has been my experience over the years that the SE often experiences severe weather when Northern Texas has a Major winter storm. For Northern Texas to have a widespread winter weather event of great magnitude, you need a surface to low form in the NW Gulf and track NE through SE Louisiana into Mississippi. This makes for a huge temperature contrast between the two regions, resulting in severe weather on the east side of the storm.

It is still too early to tell the exact track of the low, but that it is certainly a distinct possibility. It just depends on whether the low stays off shore or travels to the NE and inland.

[Stratosphere747]

I tell ya, Jeff is spot on with the possiblites, though keeping the wintery weather away from our area for the most part.

Great statement --

"Will leave it at that for now and await the next guidance runs this afternoon. Wide swings in the forecast should be expected as forecast models attempt to resolve this system. The exact track of the upper level storm will be critical in determining where winter precip. falls and any potential accumulations (similar to forecasting a hurricane 5 days out)"

[Johnny]

Stratosphere747, did Jeff send out an update today? If so, I didn't get it.

[Stratosphere747]

Stratosphere747, did Jeff send out an update today? If so, I didn't get it.

Yes...

It should be under this title --

Wet...then Winter Returns

[southerngale]

Johnny...yes, he did. I'll send it to you. (I know I'm not Strat! )

[gboudx]

Was his email specific to SETX? I think I only get emails from him when he discusses the weather that affects central TX and the DFW area.

[Johnny]

Thanks SG...for some reason I didn't it.

[Yankeegirl]

Here is Jeffs e mail that I got this morning...

Heavy rainfall expected over the next 3 days followed by a significant cool down and potential for a Winter Storm just before Christmas.

Short term:

Fog has been slow to lift this morning with current vis. remaining at or below 1/2 of a mile at many locations. In addition light and moderate rain has been streaming northward off the Gulf, and this should continue given current radar showing the next batch heading for the coast.

Now through Thursday:

Warm and very moist air mass remains in place with surface dewpoints inching toward 70. Moisture profiles becoming increasingly saturated over the next 36-48 hours suggesting heavier rainfall rates. Upper trough ejects into the central plains dragging a slow moving cold front into SE TX sometime Wednesday into Thursday. Boundary will be weak, but will lift plentiful moisture supply and produce widespread rains...some heavy, from late Tuesday to late Thursday. Given increasing PWS into the 1.3-1.6 range heavy rains appear likely and some 48-72 hour totals could exceed 4 inches where training occurs.

Winter Storm Potential:

Confidence is growing for a mixed bag of winter precip. including accumulating snow from Dec 23rd to Dec 25th. Main threat area at this time appears from Del Rio to San Antonio to College Station to Texarkana and NW of that line for accumulations of ice and snow.

Per 06Z and new 12Z GFS a deep trough quickly redevelops over northern Mexico into W TX by late Friday and digs into Saturday. Polar frontal boundary slides through the region sometime Saturday ahead of main upper level low. Strong synoptic scale lift ahead of ejecting low will produce a period of strong isentropic ascent over much of TX. Latest GFS is faster with the forecast movement of the upper low and is now out running the cold air intrusion. Even so, significant amounts of ice and or snow are still possible from SW TX through central TX to NE TX the 24th and 25th. Critical thickness values are reached over SE TX by late on the 24th with the 850mb 0C line at least 1/3rd through the region...however surface temps. are not near freezing per the guidance. With that point understood it is also important to note the rapid drying and potential dry slotting by the afternoon of the 24th which could very well scour out all the moisture before the air column can support frozen precip. We are not dealing with arctic air which is what is usually needed for winter weather in SE TX, however I feel the models are underforecasting the potential cold air advection and wet bulbing cooling processes and are thus too warm with the surface temps. Will probably also need to look carefully at wrap around moisture potential on the 25th as by this time the profile would support all snow...however the track of the upper low is critical in determining such details.

Will leave it at that for now and await the next guidance runs this afternoon. Wide swings in the forecast should be expected as forecast models attempt to resolve this system. The exact track of the upper level storm will be critical in determining where winter precip. falls and any potential accumulations (similar to forecasting a hurricane 5 days out)

[Below N.O.]

Thought for the day:

I find it a bit humorous that when neither TWC nor AccuWx show any kind of snow/ice in the forecast NOBODY seems to care or mention it.

Don't forget though that those forecasts are computer generated.

EXACTLY. And that just goes to my point.

When they don't show anything - funny how the silence is defeaning, but when the first flake pops on a graphic, it'll get posted 10X from every source.

That's cause its a WINTER WEATHER BOARD!

[jasons2k]

I think someone missed the point, oh well...

[Extremeweatherguy]

From the Lake Charles NWS:

INTERESTINGLY...THE REMNANTS OF THE COLD FRONT WASHES OUT IN THE
GULF OF MEXICO...BUT A SURFACE LOW PRESSURE SYSTEMS DEVELOPS ALONG IT ON
SATURDAY. AS THIS LOW PRESSURE SYSTEM MOVES NORTHEAST ACROSS THE
GULF SATURDAY INTO SUNDAY...THERE IS THE OUTSIDE POSSIBILITY OF
FROZEN PRECIPITATION ALONG ITS NORTHWEST QUADRANT. WILL THIS BE
CLOSE TO LOUISIANA...ITS TOO EARLY TO SAY BUT IT DOES BEAR WATCHING.

They are now officially using the wording "Frozen precipitation" as a possibility for far SE Texas and SW Louisiana!

[Lindaloo]

I think someone missed the point, oh well...

Don't worry about it. The ones who count got the point.

[gboudx]

From Norman, OK. Only the weekend forecast quoted.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
250 PM CST MON DEC 18 2006

.DISCUSSION...
...
THINGS START TO GET VERY INTERESTING BEGINNING ON SATURDAY AND CONTINUING
INTO THE CHRISTMAS HOLIDAY. POTENTIAL REMAINS FOR FROZEN
PRECIPITATION TO DEVELOP BEGINNING SATURDAY AND CONTINUING THROUGH
SUNDAY. THE 12Z GFS AND EUROPEAN MODELS REMAIN AT ODDS ON THE TRACK
OF THE CHRISTMAS HOLIDAY STORM SYSTEM. IF THE NEW GFS IS TO BE
BELIEVED... PARTS OF SOUTHERN OKLAHOMA AND NORTHERN TEXAS MAY SEE A
PERIOD OF ACCUMULATING SNOWFALL... MAINLY FROM LATE SATURDAY
AFTERNOON INTO SUNDAY MORNING. NEW EUROPEAN MODEL HAS YET TO LINE UP
WITH THIS THINKING... COMING IN SLOWER AND FARTHER SOUTH.

MODELS ARE AGREEING ON THE SOUTHERN TRACK OF THE STORM SYSTEM... THE
QUESTION IS JUST HOW FAR SOUTH IT WILL GO. PUT CHANCE POPS MAINLY
ALONG MAINLY THE SOUTHERN HALF OF OKLAHOMA AND WESTERN NORTH TEXAS.
FORECAST WILL CONTINUE TO BE FINE TUNED AS THE TRACK OF THE STORM
SYSTEM COMES BETTER UNDERSTOOD. WILL GO AHEAD AND FRESHEN UP THE SPS
TO HIGHLIGHT THE POTENTIAL FOR FROZEN PRECIPITATION DURING THE
UPCOMING HOLIDAY WEEKEND.

[Extremeweatherguy]

From Norman, OK. Only the weekend forecast quoted.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
250 PM CST MON DEC 18 2006

.DISCUSSION...
...
THINGS START TO GET VERY INTERESTING BEGINNING ON SATURDAY AND CONTINUING
INTO THE CHRISTMAS HOLIDAY. POTENTIAL REMAINS FOR FROZEN
PRECIPITATION TO DEVELOP BEGINNING SATURDAY AND CONTINUING THROUGH
SUNDAY. THE 12Z GFS AND EUROPEAN MODELS REMAIN AT ODDS ON THE TRACK
OF THE CHRISTMAS HOLIDAY STORM SYSTEM. IF THE NEW GFS IS TO BE
BELIEVED... PARTS OF SOUTHERN OKLAHOMA AND NORTHERN TEXAS MAY SEE A
PERIOD OF ACCUMULATING SNOWFALL... MAINLY FROM LATE SATURDAY
AFTERNOON INTO SUNDAY MORNING. NEW EUROPEAN MODEL HAS YET TO LINE UP
WITH THIS THINKING... COMING IN SLOWER AND FARTHER SOUTH.

MODELS ARE AGREEING ON THE SOUTHERN TRACK OF THE STORM SYSTEM... THE
QUESTION IS JUST HOW FAR SOUTH IT WILL GO. PUT CHANCE POPS MAINLY
ALONG MAINLY THE SOUTHERN HALF OF OKLAHOMA AND WESTERN NORTH TEXAS.
FORECAST WILL CONTINUE TO BE FINE TUNED AS THE TRACK OF THE STORM
SYSTEM COMES BETTER UNDERSTOOD. WILL GO AHEAD AND FRESHEN UP THE SPS
TO HIGHLIGHT THE POTENTIAL FOR FROZEN PRECIPITATION DURING THE
UPCOMING HOLIDAY WEEKEND.

That is interesting about it shifting further and further south. If this trend continues then it looks like Texas could be in a bullseye! Also, slower + further south would also mean a bigger event for central and SE Texas (which I would love to see happen).

[aggiecutter]

The Noon Ensembles really, and I do mean really, dig the trough and keep it around Christmas week. Christmas week looks stormy and cold for Texas. BTW, the Ensembles jumped on this trough and have been consistent with it for the last 8 days. I wouldn't even bother looking at its operational runs until Thursday or Friday.

At 180hrs, you'll notice another disturbance rounding the bend in the trough, fixing to head out over Texas.

Noon Ensembles:
http://wwwt.emc.ncep.noaa.gov/gmb/ens/t ... 21812.html

[Extremeweatherguy]

---Let gboudx's post take the place of this one.---

[gboudx]

From DFW. I find the end to be very interesting.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
258 PM CST MON DEC 18 2006

.DISCUSSION...
...
IN THE EXTENDED...THURSDAY AND FRIDAY ARE DRY...AND BY SATURDAY
NEXT UPPER LEVEL LOW MOVES OUT OF THE MOUNTAINS. CURRENT RUN HAS
TRACK ACROSS NEW MEXICO SATURDAY AND ACROSS NORTH TEXAS SUNDAY.
HOWEVER...GFS HAS HAD NO RUN TO RUN CONTINUITY ON THE WEEKEND
SYSTEM...WITH UPPER LOW POSITIONS FOR SUNDAY/MONDAY VARYING MORE
THAN 1000 MILES OVER THE LAST TWO DAYS. GFS ENSEMBLE SHOWS
CONSIDERABLE SPREAD ON WEEKEND 500MB LOW LOCATION AMONGST THE 12
PERTURBATIONS...AND THE 12Z OPERATIONAL RUN LOOKS ABOUT AS COLD
AS THE COLDEST THREE PERTURBATIONS. UNTIL THERE IS MORE RUN TO
RUN CONTINUITY...AND LESS ENSEMBLE SPREAD THAT ALSO AGREES WITH A
COOLER SOLUTION...I WILL NOT JUMP ON A SNOW SCENARIO JUST YET. I
FEEL IT IS CURRENTLY A LOW PROBABILITY SOLUTION BUT NOT OUT OF THE
QUESTION.

I AM TRYING TO BALANCE THE NEED TO INFORM THE PUBLIC OF POTENTIAL
WINTER WEATHER...AND THE DESIRE NOT TO PAINT A WORST CASE SCENARIO
AS THE SUGGESTED OUTCOME. NOT MENTIONING WINTER WEATHER UNTIL IT
OCCURS IS NOT EXACTLY FORECASTING...NOR IS CONSTANTLY CRYING WOLF
ABOUT WINTER PRECIPITATION. NEITHER SERVES THE PUBLIC/S BEST
INTEREST AND THE TRUTH USUALLY LIES SOMEWHERE IN BETWEEN.