TX winter wx thread: Spring-like pattern

[jasons2k]

Good link, but note there has been quite a bit of debate over the "new" map. The USDA was originally set to adopt it in 2006. However, they opted not to adopt it yet since it is very debateable if the warming trend over the last 16 years is enough to truly relocate the hardiness zones northward., e.g., is it a temporary or more permanent trend?

Lastly, I would take those very cautiously as they indicate the expected average annual low; they do not consider extreme events. And as we have all learned the hard way, it only takes a single extreme event to throw the "hardiness" maps completely out of whack. Hypothetically, if we get a record low of 10F in the middle of January, that doesn't exactly classify us as Zone 9.

[Below N.O.]

Getting back on subject, the 12z GFS says game on next week!

[Extremeweatherguy]

Latest Houston AFD...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
241 PM CST WED DEC 5 2007

.DISCUSSION...
TODAY HAS BEEN ANOTHER SUNNY DECEMBER DAY ACROSS ALL OF SOUTHEAST TEXAS.
EVERYONE HAS REACHED THE LOWER TO MID 70S EARLY THIS AFTERNOON...AND
SOME UPPER 70S WILL PROBABLY BE REACHED BEFORE SUNSET. A DRY COLD FRONT
WILL MOVE INTO THE NORTHERN AREAS TONIGHT BUT WILL HAVE LITTLE INFLUENCE
ON THE AREA WEATHER. OVERNIGHT LOWS WILL BE SLIGHTLY WARMER THAN THOSE
EXPERIENCED THIS MORNING. WITH HIGH PRESSURE MOVING OFF TO THE EAST
AND PRESSURES LOWERING TO THE LEE OF THE ROCKIES...EXPECT TO SEE PARTLY
CLOUDY SKIES STARTING ON THURSDAY AND THEN INCREASING CLOUD COVER AS
WE HEAD ON INTO THE WEEKEND. PATCHY FOG (POSSIBLY EVEN SOME DENSE SEA
FOG) MIGHT DEVELOP THURSDAY NIGHT/FRIDAY MORNING. THE COMBINATION OF
INCREASING GULF MOISTURE...A STRENGTHENING SOUTHWEST FLOW ALOFT AND
ASSOCIATED WEAK DISTURBANCES...AND A SOUTHWARD SAGGING COLD FRONT ALL
LEAN TOWARD AN INCREASING COMPLICATED AND LOW CONFIDENCE EXTENDED FORECAST.
HAVE LOW RAIN CHANCES FOR EVERYONE ON SATURDAY...THEN GRADUALLY INCREASE
POPS (ESPECIALLY UP NORTH) SATURDAY NIGHT THROUGH MONDAY AS THE FRONT
ENTERS THE PICTURE. HAVE LEANED TOWARD PARKING THE FRONT NORTH OF I-10.
IF THE BOUNDARY REMAINS NORTH OF THE CWA...SO WILL MOST OF THE RAINS.
IF THE BOUNDARY DOES SAG INTO THE AREA...THE RAINS WILL COME. THERE
MIGHT END UP BEING QUITE A DIFFERENCE IN THE WEATHER WITH COOLER AND
WETTER CONDITIONS UP NORTH AND DRIER AND WARMER CONDITIONS TOWARD THE
COAST. STAY TUNED! IT NOW LOOKS LIKE THE AREA WILL CLEAR OUT AND COOL
DOWN SOME TIME BETWEEN LATE ON TUESDAY AND EARLY ON WEDNESDAY AS THE
UPPER LOW OUT WEST OPENS AND LIFTS ON OUT AND A COLD FRONT SWEEPS THROUGH
THE AREA

Hmm. Looks like a fun pattern may be in place by next week. We could very well be looking at one of those situations where the northern areas of SE Texas are quite cold and quite wet, while the southern areas are warm and dry with a very distinct frontal boundry across the region. I wouldn't even be surprised to see a pretty big temperature spread across the region during the Sunday through Tuesday timeframe with some places struggling to get out of the 40-60 range while others are muggy and well into the 70s. By Wednesday though, it looks like the front will finally push through the entire area and we will all turn cooler and drier in it's wake. We might even have the potential to see a frost or freeze if we can clear out and calm down Wednesday and Thursday night. It doesn't look like this will be a setup for a hard freeze (in Houston) though...probably just a night or two similar to what we saw yesterday morning.

[Extremeweatherguy]

I have decided to change the title of this thread to the "TX winter weather thread" so that we can now discuss any upcoming winter events (fronts, freezes, etc) instead of only sticking to the arctic variety fronts and winter precipitation threats. This is still separate from the SE TX/SW LA thread in the US Weather section though, because this thread applies to the entire state of Texas and not just one particular region.

[Extremeweatherguy]

The 18z GFS is coming in now, and it looks very cold for next week. Take a look...

Front pushes into north Texas late Sunday night: http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_102l.gif

By Monday morning, freezing rain and sleet is falling as far south as Dallas and the leading edge of the front is quickly approaching Houston: http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_114l.gif

Monday afternoon looks Chilly. Many parts of north Texas struggle to get out of the 20s and 30s (with freezing rain, sleet and snow) and in central and southeast Texas, temperatures are steadily falling with rain and breezy north winds: http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_120l.gif

The rain and cold continues into Tuesday with another day in the 30s and 40s for north Texas and 40s and 50s for everyone else: http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_144l.gif

Wednesday morning looks very cold. A reinforcing 1043mb+ high to our northwest helps usher in a large area of temperatures in the 10s, 20s and 30s across the state (with a breeze): http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_162l.gif

Wednesday afternoon is one of the coldest of the bunch. This run is showing highs Below freezing in the panhandle, in the 30s for north Texas and in the 40s for Houston and Austin: http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_168l.gif

What is really exciting about this run is the fact that it has all of this happening within the next week! No longer are we talking long-range predictions here, instead this is now within the short to medium range time scale and much more believable.

[richtrav]

Hmm, that run looks like the cold would come down west of the Front Range, an unusual route. Still, it just looks like garden-variety cold for most of TX

Rumor has it that the US Dept of Agriculture is coming out with a new zone map of their own. Hopefully it will use more than the brief 12-14 years of data collection that were used in the less-than-ideal 1990 and 2006 maps. The 1990 map was too pessimistic and a lousy predictor of the winters that followed.

[Extremeweatherguy]

The 00z GFS continues to show a Sunday/Monday frontal passage for most of Texas (less than 100 hours from now) followed by some pretty chilly air.

Here is a look at the 00z run in detail...

Front slices into north Texas on Sunday afternoon: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_090l.gif

By Sunday evening, the front has already reached central TX. In north Texas, temperatures fall into the 20s and 30s with some frozen precipitation possible in a few places: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_096l.gif

The front has reached Houston by Monday morning and in north Texas an ice storm (with snow in the panhandle) is underway: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_108l.gif

Monday afternoon is downright chilly. Temperatures fall during the day in Houston and Austin, and in northern and northwest Texas, a wintery storm is underway. A large area of snow is falling in the panhandle and freezing rain and sleet falls in places near, and especially northwest of, the metroplex. One interesting thing though is that the immediate coast may remain warm. This run stalls the front near or just offshore, so coastal towns could remain warm and muggy while everyone else is chilly.: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_114l.gif

By Tuesday afternoon, the front has retreated back north as a warm front (according to this run). However, this is a common mistake of the models during a shallow cold air event, so it may or may not be correct. Either way, another push of cold air from the NW should help eventually push the front back south. This looks like another cold afternoon in north Texas though with highs in the 20s, 30s and 40s. The panhandle region also looks to continue seeing more and more ice and snow.: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_138l.gif

Finally, by 12am Wednesday morning, the GFS shows the front passing back through Houston and off the coast. This time it looks to be the actual "real deal" too. Strong winds filter in behind the front and Wednesday looks to be a cold day state-wide. Also, more snow and ice falls in parts of north Texas, and by this point some areas of the panhandle could be looking at a pretty serious winter event with widespread heavy accumulations of snow and ice: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_150l.gif

Sunrise Wednesday brings with it widespread lows in the 20s (northwest TX), 30s (central/north TX) and 40s (far southeast TX) and a gusty northwest breeze. Winter precipitation CONTINUES in parts of north Texas and with 850mb temperatures falling below 0C, a changeover from rain or ice to snow would be likely in areas near Dallas/Fort Worth: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_156l.gif

Wednesday afternoon has the winter storm ending in north Texas and it shows chilly high temperatures state-wide. Houston and Austin are stuck in the 40s for highs and north Texas is stuck in the 30s (with freezing or below in the panhandle): http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_162l.gif

Thursday morning brings with it a widespread freeze. The 0C line on this image doesn't really tell the tale. With fairly light winds and clear skies, the freeze line would likely extend from Houston over to Austin and up through the rest of central and north Texas: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_ten_180l.gif

..All in all, this is a pretty cold and wet run. No, it is nothing record-breaking, but it is definitely a good chill and some areas of north and northwest Texas could be looking at a pretty nasty winter storm.

[Extremeweatherguy]

Just a heads up: The 6z GFS now doesn't move the front back north on Tuesday and looks even stronger/colder than the 00z.

[lrak]

Corpus weather forecasters calling 65 as the high temp on Dec. 12th and, cold enough for me.

[double D]

Just a heads up: The 6z GFS now doesn't move the front back north on Tuesday and looks even stronger/colder than the 00z.

Usually with these type of air masses, it ends up being colder than what is forecasted by the GFS and NWS offices.......sometimes much colder.

[CaptinCrunch]

Morning 12/6 AFD, NWS FTW

AS IS TYPICAL WITH SHALLOW ARCTIC AIR MASSES...MODELS TRENDING
TOWARD AN EARLIER FROPA AS EVENT APPROACHES. ARCTIC AIR MAY
IMPINGE ON NW CWA BEFORE DAYBREAK SUNDAY. VIGOROUS MOIST ADVECTION
WILL PERSIST THROUGHOUT THE WEEKEND...AND EXPECT CONSIDERABLE
CONVECTION IN VICINITY OF FRONTAL BOUNDARY.

PERSISTENT WARM ADVECTION ABOVE THE FRONTAL LAYER WILL ASSURE
SIGNIFICANT PRECIP CHANCES FOR AS MUCH AS 72 HOURS PAST FROPA.
WITH STRONG SOUTHERLY FLOW 850-750MB...TREMENDOUS WARM NOSE WILL
PREVAIL THROUGHOUT EVENT. DEPTH OF ABOVE-FREEZING LAYER SEVERAL
THOUSAND FEET...WITH TEMPS AT PEAK OF NOSE IN EXCESS OF 50F. WITH
VERY SHALLOW SFC LAYER...AND TEMPS ONLY FLIRTING WITH FREEZING IN
NW ZONES TUESDAY MORNING...EXPECT WINTER WX THREAT TO BE LIMITED
TO BRIEF FREEZING RAIN. HAVE INTRODUCED RA OR FZRA WORDING IN NW
FOR LATE MONDAY NIGHT INTO TUESDAY MORNING. A BORDERLINE EVENT ON
DAYS 6-7...SO STILL PLENTY OF UNCERTAINTY WITH SFC TEMPERATURES.
GFS/ECMWF PERFECT PROG SFC TEMPS PLACE FREEZING LINE IN NW CWA
NEAR WHAT MOS INTERPOLATION WOULD YIELD. GFS ENSEMBLE MOS A BIT
COLDER...WITH FREEZING LINE QUITE CLOSE TO METROPLEX. REGARDLESS
OF SFC TEMP PROGS...SIGNIFICANT PRECIP FALLING FROM WARM LAYER MAY
ACTUALLY RAISE SFC TEMPS...THUS LIMITING ICE ACCUMULATION. THE
PROCESS INVOLVES HEAT RELEASED DURING CONDENSATION...MECHANICALLY
FORCED DOWNWARD TRANSPORT OF WARM AIR DURING MODERATE/HEAVY
PRECIPITATION...AS WELL AS THE WARM WATER IMPARTING HEAT TO THE
SURFACE ON WHICH IT FALLS. THIS IS SIMILAR TO RA/FZRA EVENT OF
MID-JANUARY 2007...DURING WHICH MODERATE/HEAVY RAIN FELL IN THE
METROPLEX WITH SFC TEMPERATURES BELOW FREEZING...BUT WITH LITTLE
OR NO ICE ACCUMULATION ON THE GROUND. (SIGNIFICANT ICE STORM
OCCURRED IN PORTIONS OF CWA DURING THAT EVENT...BUT SFC TEMPS WERE
CONSIDERABLY COLDER THAN WHAT IS ANTICIPATED EARLY NEXT WEEK.)

[Portastorm]

The plot thickens ... read the latest from S2K expert forecaster Jeff Lindner

****
Surface high will retreat eastward over the next 24 hours allowing Bay of Campeche air mass to surge northward into TX. This air mass is characterized by dewpoints in the mid to upper 60’s which will spread across nearshore water temps. in the lower 60’s. Such events usually produce dense sea fog as the air is chilled to saturation. However winds will be increasing from the south and this may help keep the sea fog from becoming extremely dense…will have to see…as typically we do not have such issues until Jan or Feb.

Stout sub-tropical high over the SE US will build westward as deep trough develops over the western US into N Mexico. Rising mid level heights and prolonged onshore flow will mean temperatures will run 20-25 degrees above average on the morning lows and 10-15 degrees above average on the daytime highs. In fact low temps. the next several mornings will be higher than the average high temps….and it will feel much more like May than December. May see just enough moisture return by Saturday to produce a slight chance of showers under the capping inversion.

Sunday Onward:

Forecasting nightmare is at hand this morning with shallow but very cold arctic air mass poised to our north, developing trough to our west, and sub-tropical high over the SE US. Arctic boundary extends from the mid-Atlantic region to NW Montana with temps. in the 1’s to 10’s behind this boundary. Large pool of very dense cold air with temps. in the -20’s and -30’s exists over NE Alaska into NW Canada.

Upper air pattern will evolve as such the dense and very cold air mass to our north will begin to bleed southward under its own density along with high pressure rises. Long wave trough as shown on the GFS, CMC, and ECMWF hangs back over the SW US through the middle of next week…a pattern that would favor a continued warm SW flow aloft and very warm surface temps. HOWEVER given the intensity and density of the air mass I believe the arctic air will undercut the unfavorable flow aloft and move southward being re-enforced by frontal convection and post frontal ice/snow accumulations across the plains. I have very little guidance support for this except the most recent GFS runs…however models do not handle shallow arctic air masses well east of the Rockies and tend to be too slow and weak with the boundaries when being overrun by SW flow aloft. The pattern is not all that different from the outbreak of cold and ice mid Jan 06.

Will go with front entering TX Sunday morning and this may be slow and moving southward during the day with temps. falling easily 20 degrees with the frontal passage. Front will slow Sunday night as it reaches SE TX and strong upper SW flow parallels the boundary. I feel that the air mass will be dense enough to go ahead and push offshore under its own power bringing most of SE TX into the cold sector. Following this reasoning…temps. will need the knife and will start with highs on Monday by cutting at least 20 degrees off guidance. Front may have a much harder time getting through Matagorda Bay and it is very possible that Monday afternoon temps. range from the 30’s N to 80’s SW and everybody else falls somewhere in between. Expect widespread heavy frontal and post frontal rainfall as impressive warm advection regime establishes over top of the shallow cold dome as SW US upper trough moves eastward into the state Monday and Tuesday.

Model profiles maintain a very healthy warm nose with near 50 degree temps. above a much colder surface air layer in strong overrunning/isentropic regime…hence P-type issues are not expected over SE TX in the post-frontal air mass. GFS surface 32 degree line plunges into N TX and then into C TX where potential does exist for surface icing although given such a warm profile just above the surface…heavier rainfall may transport warmer air downward requiring temps. into the 20’s to produce significant icing instead of just 32. Will need to keep a very close eye on snow/ice accumulations to our north as upstream air mass will flow across this region and will not modify as much as it would if there were no ground coverage.

Large upper trough ejects into the southern plains around Wednesday of next week with skies clearing and arctic boundary pushing on out into the Gulf of Mexico. Skies clear out Wed afternoon and a very cold night looks possible Thursday AM with the potential for widespread freezing temps.

Stay tuned as very large temp. forecast changes appear likely over the next few days as this event becomes better defined and density of arctic air mass is realized. Expect to see large trending downward of temps. in guidance and local forecast…however the entire period from Mon-Wed is very uncertain and is completely tied to the location of the arctic boundary and where is pulls of stationary and waves across the area.

[gboudx]

I was just coming here to post that Portastorm.

Jeff mentions the mid Jan 06 event, but I wonder if he means the mid-Jan 07 event? We had a similar setup in mid Jan of this year, with the cold and rain. In my area, and I think most of the Metroplex, the heavier rain increased surface temps enough to not allow ice to form.

[CaptinCrunch]

I was just coming here to post that Portastorm.

Jeff mentions the mid Jan 06 event, but I wonder if he means the mid-Jan 07 event? We had a similar setup in mid Jan of this year, with the cold and rain. In my area, and I think most of the Metroplex, the heavier rain increased surface temps enough to not allow ice to form.

You are correct, as it was stated in the morning AFD. Very warm nose, and mod to heavy rain warmed the lower layer and did not allow for any frz precip to fall or accumluate on the surface, even with surface temps at 31 degrees.

[CaptinCrunch]

SPECIAL WEATHER STATMENT NWS FTW TX

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

A COLD FRONT AND UPPER LEVEL DISTURBANCE WILL MOVE INTO NORTH TEXAS
ON SUNDAY...WITH WAVES OF COLD RAIN EXPECTED THROUGH WEDNESDAY.
TEMPERATURES WILL FALL ACROSS THE REGION DURING THE DAY ON
SUNDAY...WHILE SHOWERS AND THUNDERSTORMS DEVELOP ACROSS NORTH TEXAS.
THE MOST NUMEROUS SHOWERS AND STORMS WILL FIRST OCCUR ALONG THE RED
RIVER...BEFORE PROGRESSING ACROSS ALL OF NORTH TEXAS SUNDAY NIGHT
INTO MONDAY.

COLD...MODIFIED ARCTIC AIR WILL FILTER INTO NORTH TEXAS SUNDAY NIGHT
THROUGH TUESDAY. HIGHS ON MONDAY AND TUESDAY WILL ONLY CLIMB INTO
THE LOW TO MID 40S IN MANY AREAS...WITH A COLD RAIN FALLING. THERE
WILL BE A SLIGHT CHANCE OF FREEZING RAIN ALONG AND NORTHWEST OF A
BRECKENRIDGE TO GAINESVILLE LINE TUESDAY MORNING...BUT AT THIS TIME
LITTLE ICE ACCUMULATION IS EXPECTED. LOW TEMPERATURES MONDAY AND
TUESDAY NIGHTS WILL GENERALLY HOVER IN THE LOW TO MID 30S.

THERE IS STILL A MODERATE DEGREE OF UNCERTAINTY WITH THIS
SYSTEM...AND THE FORECAST WILL BE REFINED AS THE WEEKEND APPROACHES.
STAY TUNED TO NOAA WEATHER RADIO FOR THE LATEST FORECASTS.

I have that funny feeling of sliding on frozen water....hhmmm.

[gboudx]

I have that funny feeling of sliding on frozen water....hhmmm.

I agree. I don't get why they are issuing an SWS for the entire CWA if only the NW counties "might" get ice. It doesn't make sense to issue an SWS for a cold rain, unless they believe there's a great enough chance of something frozen.

[CaptinCrunch]

I have that funny feeling of sliding on frozen water....hhmmm.

I agree. I don't get why they are issuing an SWS for the entire CWA if only the NW counties "might" get ice. It doesn't make sense to issue an SWS for a cold rain, unless they believe there's a great enough chance of something frozen.

I think it's their way of saying "HEY", you better watch out, you better not cry, you better not pout, I'm telling you why, old man winter is coming..... TO TOWN..........

ARCTIC air will NOT be as modified as first thought.

[double D]

The San Antonio/Austin NWS is not buying the 12z GFS and want to bring the front in Wednesday. This has the potential to bust HUGE!
Check out the high temp. for Monday and Tuesday.

Monday: A 40 percent chance of showers and thunderstorms. Cloudy, with a high near 75. Southeast wind around 10 mph.

Monday Night: A 40 percent chance of showers and thunderstorms. Cloudy, with a low around 52.

Tuesday: A 30 percent chance of showers and thunderstorms. Cloudy, with a high near 61.

[cctxhurricanewatcher]

The San Antonio/Austin NWS is not buying the 12z GFS and want to bring the front in Wednesday. This has the potential to bust HUGE!
Check out the high temp. for Monday and Tuesday.

Monday: A 40 percent chance of showers and thunderstorms. Cloudy, with a high near 75. Southeast wind around 10 mph.

Monday Night: A 40 percent chance of showers and thunderstorms. Cloudy, with a low around 52.

Tuesday: A 30 percent chance of showers and thunderstorms. Cloudy, with a high near 61.

Wouldn't be the first or last times they bust on a forecast in a big way.

[double D]

Talk about surrounding offices not collaborating. The San Angelo NWS says the GFS is probably to slow with the front and The San Antonio/Austin NWS says it's to fast and is an outlier.