TX winter wx thread: Spring-like pattern

[gboudx]

The lack of continuity could simply be that they just don't know due to density of the airmass. The comparison was made by the DFW office to the airmass last January. In that one, the temp contrast was pretty sharp in just over several miles in some cases. It's probably difficult for them to figure out just how this airmass will ooze it's way into the different CWA's, considering these airmasses are able to move beneath the prevailing upper-air flow. Give it a few days to sort this out.

[Extremeweatherguy]

The Houston NWS is also holding off on a frontal passage until Tuesday evening. This is probably a smart move ATM (due to the models not all being in total agreement), but in the future, it would not surprise me to see the timing moved up some. The latest Houston AFD stresses that there is A LOT OF UNCERTAINTY with this forecast and it is subject to major changes.

[CaptinCrunch]

I think this says it all!!

Afternoon AFD FTW TX

THE MAIN DIFFERENCE BETWEEN A MIXED BAG OF PRECIPITATION VERSUS
STRICTLY COLD RAIN WILL HINGE ON THE DEPTH OF THE MODIFIED ARCTIC
AIR MASS. 850MB TEMPS STRUGGLE TO FALL BELOW 0 CELSIUS DURING THE
EVENT...WITH THE EXCEPTION OF OUR FAR NORTHWEST ZONES.
HOWEVER...THE LOW LEVEL COLD AIR /925MB AND BELOW/ MAY VERY WELL
FALL BELOW FREEZING OVER A LARGER PORTION OF OUR FORECAST AREA.
THEREFORE...IF NORTH TEXAS DOES EXPERIENCE ANY FROZEN
PRECIPITATION...IT WILL BE FREEZING RAIN DUE TO THE SHALLOW COLD
AIR AND INTENSE WARM NOSE. ANOTHER QUESTION MARK REVOLVES AROUND
AN INCREASE IN LOW LEVEL TEMPERATURES AS THE RAIN FALLS AND
MECHANICALLY TRANSPORTS WARMER TEMPERATURES ALOFT DOWN TO THE
SURFACE...WHICH WOULD INHIBIT FREEZING RAIN CHANCES. AT THIS
TIME...WILL REMAIN CONSISTENT WILL THE PREVIOUS FORECAST AND
RETAIN A SLIGHT CHANCE FOR FREEZING RAIN IN OUR NORTHWEST CWA
/ALONG AND NORTHWEST OF A BRECKENRIDGE TO GAINESVILLE LINE/
TUESDAY MORNING. YET OTHER QUESTIONS SURROUND HOW WELL THE GFS IS
HANDLING THE DEPTH OF THE COLD AIR...AS MIXED PRECIP MAY NEED TO
BE PULLED FARTHER SOUTHEAST WITH LATER FORECASTS.

NEVERTHELESS...MODERATE UNCERTAINTY SURROUNDS THIS UPCOMING
WEATHER EVENT. ONCE THE UPPER WAVE MAKES LANDFALL AND IS SAMPLED
BY THE UPPER AIR NETWORK...AND THE COLD AIR BEGINS TO
DISLODGE SOUTHWARD...WE WILL GAIN A BETTER HANDLE ON THIS CHANGING
SITUATION.

[Extremeweatherguy]

The 18z GFS looks faster in the short term (front reaches central TX by Monday morning), but then it stalls the front out for a good day or so (across central and north TX) and because of this, it becomes slower than the 12z in the long run. This run finally goes on to push the front offshore by Tuesday afternoon/evening with the front passing through the Houston metro area sometime between 12pm and 6pm on Tuesday.

[wall_cloud]

faster is probably better. The EWX forecast seems a bit "out there". Given the density of this cold airmass, I wouldn't be surprised to see it go all the way to the coast once it starts sliding Sunday/Monday. I would be quite uneasy with the temps so warm on Monday and Tuesday across the Hill Country and SE Texas. Just my 0.02

[Ed Mahmoud]

JB sees DFW near 80ºF Sunday and daytime highs Monday and Tuesday not getting out of the 30sF.


Of course, I'd rather see ice here in Houston, but if we get a decent rain, I'll take it.

[gboudx]

SWS for entire DFW CWA continues for a cold rain this weekend into early next week. I still don't see the point of this SWS for a cold rain, unless they think it could be worse with ice.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
500 AM CST FRI DEC 7 2007

...COLD SNAP AND RAIN HEADED FOR NORTH TEXAS LATE THIS WEEKEND
AND EARLY NEXT WEEK...

A STRONG COLD FRONT WILL MOVE INTO NORTH TEXAS ON SUNDAY. SHOWERS
AND THUNDERSTORMS WILL PRECEDE AND ACCOMPANY THE FRONT...WITH
PROLONGED CHANCES OF COLD RAIN AFTER ITS PASSAGE.

THERE IS A CHANCE OF FREEZING RAIN TUESDAY MORNING ALONG AND
NORTHWEST OF A LINE FROM CISCO TO SHERMAN/DENISON. AT THIS TIME...
IT APPEARS TEMPERATURES WILL ONLY BRIEFLY DIP TO OR BELOW
FREEZING. AS SUCH...LITTLE ICE ACCUMULATION IS EXPECTED.
HOWEVER...THERE IS STILL SOME UNCERTAINTY ABOUT SURFACE
TEMPERATURES AND HOW THE RAIN MAY AFFECT MORNING LOWS TUESDAY.

STAY TUNED TO NOAA WEATHER RADIO OR VISIT WEATHER.GOV FOR THE
LATEST INFORMATION.

[double D]

I think their just giving people a heads up, becuase sometimes these air masses are colder than what is forecasted and they don't want people to be caught off gaurd.

I might be wrong but usually when these type of air masses start heading south, they keep heading south. I remember last year when the GFS wanted to bring an arctic airmass back north as a warm front and the Austin/San Antonio NWS kept buying into that, only to bust about 30 degrees when it didn't happen. Well guess what, they are doing it again. Who knows, they might be right this time.....we shall see.

[cctxhurricanewatcher]

I think their just giving people a heads up, becuase sometimes these air masses are colder than what is forecasted and they don't want people to be caught off gaurd.

I might be wrong but usually when these type of air masses start heading south, they keep heading south. I remember last year when the GFS wanted to bring an arctic airmass back north as a warm front and the Austin/San Antonio NWS kept buying into that, only to bust about 30 degrees when it didn't happen. Well guess what, they are doing it again. Who knows, they might be right this time.....we shall see.

That's correct. NWS Corpus and Brownsville are doing the same thing, with NWS Corpus leaving the door open in their overnight AFD to change their minds on it.

[double D]

Who says we can't have a white Chirstmas in Texas this year. Warning: Entertainment purposes only!!!

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer//gfs/12/gfs_ten348384_m.shtml

[gboudx]

That's one of the better winter storms I've seen the GFS drop on Texas.

[vbhoutex]

This is the latest from Jeff. Looks like a weird weather week!!

Southerly flow has returned moist air mass to the region this morning with surface dewpoints in the mid to upper 50’s. Mid 60’s to near 70 degree dewpoints will be flowing northward from the Bay of Campeche over the next 24 hours making for May feeling weather instead of December. With nearshore water temps. in the lower 60’s and expected dewpoints well above that value…sea fog may become a problem as warm moist air is chilled to saturated near the coast. However winds may stay in the 10-15mph range keeping visibilities along the coast from tanking to near zero.



Very warm weekend on tap as trough over the SW US causes moist southerly air to flow northward into a developing storm system over the western high plains. Record highs will be approached today through Sunday at all climate sites and some of the records may fall. Rain chances will increase starting Saturday as the moisture depth deepens and noisy SW flow aloft brings disturbances across the area. A stronger disturbance looks to cross the area Sunday with a good shot at showers mainly N of I-10.



Early Next Week:



Forecasting nightmare continues as very shallow but very cold arctic air mass is dislodged from NW Canada and sent southward through the plains while impressive SSW to SW upper flow screams away attempting to fight back the cold air intrusion. Models continue to be of little help and do not show a frontal passage across SE TX until Tuesday evening…they are suggesting the arctic boundary stalls out across C TX early Monday for 24-36 hours. Profile soundings from the GFS show this air mass is very shallow only extending to the 925mb to 900mb level with the 850mb cold front stalled over OK by early Monday as strong SW flow aloft pushes against this very dense air mass. Feel at the surface the pure density of the cold air which will only be about 1000-2000 ft thick may ooze its way on southward even under horribly unfavorable flow aloft. Temperature bust of 30-35 degrees will be possible on Monday and Tuesday as the boundary enters into the region and then waves back and forth across the area. Cold side of the boundry will be wet with temps. holding in the 30’s and 40’s while warm side will be drier and muggy with temps in the 70’s to near 80. Front could actually pass a point one hour dropping the temp into the 40’s only to wave back northward the next hour brining the temp back into the 60’s or 70’s. Almost pointless to attempt any kind of temperature forecast with this set up as there is really no idea or telling where the front pulls up stationary. Given the upper level flow pattern one could stall the front well N of the region over S OK and have a seemingly straight forward forecast of warm and muggy….however more than one an arctic front has defied unfavorable flow aloft and model guidance before and pressed on southward due to how heavy its shallow air mass is.



With all this in mind I will bring the front into SE TX early Monday morning and stall it between Huntsville and Downtown Houston through Tuesday evening extending back WSW to between Wharton and College Station. Rain chances will be very high through this period and we will have to watch precip. totals south of the boundary as they may add up over time. As explained above temps. N of the front will be cold (winter) while south of the front it will be warm and muggy (summer).



As the upper air trough ejects out of the SW US Tuesday and Wednesday the front pushes on off the coast with everybody going into the cold sector. Rain will linger behind the boundary into early Thursday, and Wednesday will likely be very cold given cold air advection, clouds, and rain with temps falling or holding steady in the 30’s and 40’s. Thursday still looks like the coldest morning…if skies clear and winds go calm freezing temps. may be possible. Warm up begins a week from today.



Large change to temp. forecast should be expected starting on Monday as the arctic boundary gets into the area and once it is determined how far south it will push.

[cctxhurricanewatcher]

Who says we can't have a white Chirstmas in Texas this year. Warning: Entertainment purposes only!!!

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer//gfs/12/gfs_ten348384_m.shtml

LOL! This was bound to happen.

Silly GFS!

[Ed Mahmoud]

Who says we can't have a white Chirstmas in Texas this year. Warning: Entertainment purposes only!!!

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer//gfs/12/gfs_ten348384_m.shtml

LOL! This was bound to happen.

Silly GFS!

The GFS, before it lost it, had the 2004 White Christmas in South Texas for a couple of runs.




This is why weather is more fun in Texas. Four seasons, sometimes in 2 days. In Florida, it is hurricane season, or it isn't, and whereas a few inches of snow is a novelty (if one doesn't have to drive), a hurricane can damage your home and increase your homeowners even if it doesn't damage your home.

[wall_cloud]

SWS for entire DFW CWA continues for a cold rain this weekend into early next week. I still don't see the point of this SWS for a cold rain, unless they think it could be worse with ice.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
500 AM CST FRI DEC 7 2007

...COLD SNAP AND RAIN HEADED FOR NORTH TEXAS LATE THIS WEEKEND
AND EARLY NEXT WEEK...

A STRONG COLD FRONT WILL MOVE INTO NORTH TEXAS ON SUNDAY. SHOWERS
AND THUNDERSTORMS WILL PRECEDE AND ACCOMPANY THE FRONT...WITH
PROLONGED CHANCES OF COLD RAIN AFTER ITS PASSAGE.

THERE IS A CHANCE OF FREEZING RAIN TUESDAY MORNING ALONG AND
NORTHWEST OF A LINE FROM CISCO TO SHERMAN/DENISON. AT THIS TIME...
IT APPEARS TEMPERATURES WILL ONLY BRIEFLY DIP TO OR BELOW
FREEZING. AS SUCH...LITTLE ICE ACCUMULATION IS EXPECTED.
HOWEVER...THERE IS STILL SOME UNCERTAINTY ABOUT SURFACE
TEMPERATURES AND HOW THE RAIN MAY AFFECT MORNING LOWS TUESDAY.

STAY TUNED TO NOAA WEATHER RADIO OR VISIT WEATHER.GOV FOR THE
LATEST INFORMATION.

First, an SPS is generally written for the entire CWA as a heads up to significant changes on the horizon. These aren't as specific as warnings with regard to the area over which they are issued. Secondly, a rain that is that cold (i.e. mid/upper 30s) is a significant change over what has been experienced the past several days over that area (like 40+ degrees colder). SPS products are sometimes issued simply for drastic changes in temperature, not just precipitation.

[wall_cloud]

I think their just giving people a heads up, becuase sometimes these air masses are colder than what is forecasted and they don't want people to be caught off gaurd.

I might be wrong but usually when these type of air masses start heading south, they keep heading south. I remember last year when the GFS wanted to bring an arctic airmass back north as a warm front and the Austin/San Antonio NWS kept buying into that, only to bust about 30 degrees when it didn't happen. Well guess what, they are doing it again. Who knows, they might be right this time.....we shall see.

yeah, those arctic/strong canadian airmasses tend NOT to back up once they head south. They are usually too dense to erode that easily. That said, look at the panhandle. Amarillo is a nice 75 degrees while Pampa and Dumas (a short hour drive to the northeast and north) are 30 degrees colder. This airmass has parked across the area today, leaving quite a baroclinic zone. Watch out for some light freezing rain/drizzle as well as dense fog behind this boundary, while folks to the south of it are wearing shorts. This boundary MAY hang up one more day before diving south with the aid of some mid/upper-level energy but once it gets moving, there isn't much to stop it.

[Extremeweatherguy]

The 18z GFS, as with the last few runs, looks fishy. It moves the front all the way south into northern sections of southeast and central TX on Monday before stalling it and moving it way back northwest into Oklahoma and the panhandle by Tuesday. As many have said, this is NOT likely to actually happen with a strong canadian airmass, and I believe that the shallowness of this cold air is giving the models quite a headache. I fully expect to see many temperature bust out of this with the current 79˚ forecasted for Houston next Tuesday possibly busting by up to 30+ degrees if the front decides to keep moving south Monday afternoon instead of stalling and lifting back north.

[jinftl]

When will the potential for much colder weather translate into the actual forecast?

NWS Forecast
Issued by: National Weather Service Houston, TX
Last Update: 4:41 pm CST Dec 7, 2007

---------------------------------------------------------------------
Tonight: Areas of fog after midnight. Otherwise, mostly cloudy, with a low around 67. South wind between 5 and 10 mph becoming calm.

Saturday: Areas of fog before 9am. Otherwise, mostly cloudy, with a high near 82. South wind between 10 and 15 mph, with gusts as high as 20 mph.

Saturday Night: A 20 percent chance of showers after midnight. Areas of fog after midnight. Otherwise, mostly cloudy, with a low around 70. Southeast wind around 10 mph.

Sunday: A slight chance of showers, with thunderstorms also possible after 8am. Areas of fog before 8am. Otherwise, mostly cloudy, with a high near 81. South wind between 10 and 15 mph, with gusts as high as 20 mph. Chance of precipitation is 20%.

Sunday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 66. Calm wind becoming southeast around 5 mph.

Monday: A 20 percent chance of showers. Mostly cloudy, with a high near 77.

Monday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 69.

Tuesday: A 20 percent chance of showers. Mostly cloudy, with a high near 79.

Tuesday Night: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 62.

Wednesday: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 69.

Wednesday Night: A 30 percent chance of showers. Mostly cloudy, with a low around 53.

Thursday: A 20 percent chance of showers. Mostly cloudy, with a high near 62.

Thursday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 49.

Friday: A 20 percent chance of showers. Mostly cloudy, with a high near 63.

[wall_cloud]

jinftl,

interestingly enough, the IAH forecast is at or above the 00Z MEX (that they are verified against) for Monday-Wednesday. I don't know that I'd do that, especially on Tuesday and Wednesday.

[TexasStooge]

Here are the travel trouble spots from Saturday through Tuesday:

ABILENE:

Sunday: 55°F/32°F
Monday: 36°F/32°F
Tuesday: 47°F/30°F

AMARILLO:

Saturday: 59°F/26°F
Sunday: 31°F/19°F
Monday: 31°F/23°F
Tuesday: 33°F/22°F

DALHART:

Saturday: 52°F/22°F
Sunday: 29°F/17°F
Monday: 27°F/20°F
Tuesday: 32°F/18°F

LUBBOCK:

Sunday: 41°F/25°F
Monday: 28°F/28°F
Tuesday: 41°F/25°F

WICHITA FALLS:

Sunday: 51°F/29°F
Monday: 38°F/33°F
Tuesday: 37°F/31°F