Upcoming cold for the South (Models, Maps, Discussions)

[Tyler]

Euro day 4 map:
NOTE: Keep in mind we can't see between day 3 and 4, becuase the Euro does not go in 6 hour increments like the GFS. If you look at day 3 and 4, the Euro appears colder than the GFS, and I'd bet 850 temps drop to -10...

[vbhoutex]

Sorry man but if the high is centered over Colorado than we will be even colder. This air looks colder than what we saw in early December. If it stays cloudy for most of the day on Saturday with a persistent strong northerly flow...I don't see us getting out of the 30's.

I'm not sure about the 30's for highs, but low 40's appears to be the highest to me. Lows in the 20's over most of SE TX unless the models change aagain and it appears they are all lining up together at this point. Not going to hold my breath, but the trend says that is what we will see. Unfortunately, at least in my book, we will see a quick warm up come Monday.

One of the thiings that will moderate this hit quickly is the lack of snow cover.

[Tyler]

After we get done with this strong arctic intrusion, we then look back up into Canada on Day 7. BITTERLY cold air flows into Central Canada by day 7, the question is, where does the egg of cold air go?

12 ECMWF day 7 850MB temp map:

[weatherlover427]

Send some of that over here, it's 90 degrees right now and it was 93 yesterday! I hate having no a/c.

[Tyler]

FYI, 18z NAM colder, and the high pressure is about 1MB stronger through the cycle...

As we get closer to the event, models continue to trend colder, and strengthen the high.

[weatherrabbit_tx]

19-22 for hooks airport tomball, possible colder up in conroe at the airport sunday am, however I have a feeling this is going to updated in the direction of lower, all depends on the 0z run...........

[Extremeweatherguy]

this is going to be a very active weather weekend! Just 2 more days and counting...

[Extremeweatherguy]

19-22 for hooks airport tomball, possible colder up in conroe at the airport sunday am, however I have a feeling this is going to updated in the direction of lower, all depends on the 0z run...........

yes...looks like things are really coming together. I would not be surprised to see upper teens at Conroe and Hooks and near 20 at IAH in the worst case scenario. Also...I do not see our high getting above 45 on Saturday...and I think we actually will see our high in the morning with falling temps. through the afternoon. We will probably be in the 30s for a good chunk of the afternoon with the strong CAA. I HOPE we can squeeze a surprise flurry out of this too!

[Extremeweatherguy]

part of the Dallas Afternoon AFD:

MEANWHILE...GUIDANCE FROM ALL OF THE AMERICAN MODELS...AS WELL AS
FROM THE CMC/ECMWF/UKMET...CONTINUE TO INDICATE A HIGHLY AMPLIFIED
FLOW REGIME DEVELOPING ACROSS THE WESTERN U.S. BY LATE THURSDAY...AS
UPPER RIDGE BECOMES SANDWICHED IN BETWEEN A POWERFUL NORTH PACIFIC
VORT MAX AND A DEEPENING EXTENSION OF THE HUDSON BAY VORTEX. A VERY
COLD SURFACE AIRMASS WILL DEVELOP IN RESPONSE TO THIS PATTERN...AND
THIS AIRMASS IS FORECAST TO PUSH RAPIDLY SOUTHWARD ACROSS THE
FORECAST AREA DURING THE DAY ON FRIDAY. STRONG LOW-LEVEL COLD
ADVECTION WILL RESULT IN FALLING TEMPERATURES THROUGH THE DAY...AND
MOST LOCATIONS EXCLUDING THE SOUTHEAST ZONES WILL SEE MAXIMUM
TEMPERATURES ACHIEVED DURING THE MORNING HOURS.

A CUTOFF UPPER LOW CURRENTLY LOCATED WEST OF THE BAJA PENINSULA
CONTINUES TO BE A COMPLICATING FACTOR CONCERNING PRECIPITATION
DEVELOPMENT ACROSS THE AREA. THE LATEST GFS RUN HAS COME IN MUCH
WETTER THAN PREVIOUS RUNS...WITH THE NGM/NAM/CMC GUIDANCE A BIT
DRIER AND FURTHER SOUTHEAST WITH BULK OF THE QPF. AN INSPECTION OF
ISENTROPIC PROGS SUGGESTS THAT CONTRIBUTIONS TO VERTICAL MOTION FROM
THIS COMPONENT WILL BE WEAK AT BEST...WITH BULK OF THE LARGE SCALE
VERTICAL MOTION LIKELY BEING GENERATED FROM LOW-LEVEL WARM
ADVECTION. HOWEVER...THE SYSTEM IS FORECAST TO DEAMPLIFY AS IT
APPROACHES WEST TEXAS...WITH THE GFS LIKELY OVER-FORECASTING
RESULTANT STRENGTH OF THE LOW-LEVEL WARM ADVECTION. FURTHERMORE...
ORIENTATION OF THE UPPER SYSTEM WILL RESULT IN CONFLUENT FLOW ACROSS
NORTH TEXAS...WITH SUBSIDENCE RESULTING IN AN UNFAVORABLE
ENVIRONMENT FOR WIDESPREAD PRECIPITATION. WILL INCREASE POPS ACROSS
THE SOUTHEAST ZONES...AS THIS IS THE AREA WHERE WARM ADVECTION WILL
BE STRONGEST AND A NARROW WARM SECTOR AIRMASS MAY SPREAD INLAND.
WILL ALSO REINTRODUCE ISOLATED THUNDER INTO THE FORECAST...WITH
MID-LEVEL LAPSE RATES AND RETURN OF LOW-LEVEL MOISTURE LOOKING
SLIGHTLY MORE FAVORABLE FOR CONVECTION.

COLD TEMPERATURES WILL CONTINUE ON SATURDAY AND SATURDAY NIGHT...
WITH MAXIMUMS STRUGGLING TO MAKE IT INTO THE 40S ON SATURDAY...GIVEN
UNDER VERY COLD AIR ALOFT. A HARD FREEZE IS EXPECTED FOR ALL
LOCATIONS ON SUNDAY MORNING...WITH VERY LOW DEWPOINTS AND LIGHT
WINDS SUPPORTING TEMPERATURES IN THE MID-TEENS...PARTICULARLY ACROSS
THE NORTH AND NORTHWEST ZONES. RETURN FLOW WILL BEGIN ON MONDAY
MORNING...WITH ANOTHER WEAKER FRONT PROGGED TO SLIP INTO THE AREA ON
MONDAY NIGHT. A STRONGER UPPER SYSTEM STILL MAY AFFECT THE AREA
SOMETIME TOWARD THE MIDDLE OF NEXT WEEK...BUT SIGNIFICANT
VARIABILITY IN GFSLR/ECMWF OUTPUT PRECLUDE ANYTHING OTHER THAN
SLIGHT CHANCE POPS AT THIS TIME.

[Tyler]

19-22 for hooks airport tomball, possible colder up in conroe at the airport sunday am, however I have a feeling this is going to updated in the direction of lower, all depends on the 0z run...........

yes...looks like things are really coming together. I would not be surprised to see upper teens at Conroe and Hooks and near 20 at IAH in the worst case scenario. Also...I do not see our high getting above 45 on Saturday...and I think we actually will see our high in the morning with falling temps. through the afternoon. We will probably be in the 30s for a good chunk of the afternoon with the strong CAA. I HOPE we can squeeze a surprise flurry out of this too!

Strongly agree, except for the flurry part. Moisture will be all gone, and we'll be bone dry by the time the cold air arrives. Points eastward have a better chance at seeing some wintry precip. Then again, you never know!

[Tyler]

Both Dallas and Corpus Christi undercutting MOS guidance by a good 2 catagories for saturday and sunday, realizing this airmass means business, we can only hope Houston does the same. Shreveport, however, followed the MOS guidance verbatim... WRONG thing to do.

[Brent]

Birmingham:

LATEST MODEL RUNS NO DOUBT HAVE THE SNOW MONGERS` HEARTS
A-FLUTTERING. ALL OF THE 12Z MODEL RUNS NOW SHOW A SIGNIFICANT
PRECIPITATION EVENT SHAPING UP FRIDAY NIGHT INTO EARLY SATURDAY...AS
THE UPPER LEVEL LOW NOW OFF THE BAJA CALIFORNIA COAST MOVES EAST AND
COMBINES WITH SHORTWAVE ENERGY DIGGING SOUTHWARD ALONG THE WEST SIDE
OF THE EASTERN U.S. LONGWAVE TROF. THIS IS PROBABLY THE CLOSEST CALL
WE`VE HAD WITH SIGNIFICANT WINTER WEATHER SO FAR THIS WINTER...AND
THE DEGREE OF SIGNIFICANCE IS STILL TO BE DETERMINED.

THE AMOUNT OF MOISTURE IS BECOMING LESS AND LESS OF A QUESTION...AS
THE GFS/ETA/UKMET/EURO ALL SHOW (TO VARYING DEGREES) A BROAD SWATH
OF PRECIPITATION SURGING INTO ALABAMA LATE FRIDAY INTO FRIDAY NIGHT.
THE 12Z ETA WAS NOT AS AGRESSIVE AS THE OTHER MODELS WITH ITS
QPF...ALTHOUGH THE FRESH 18Z RUN HAS TRENDED IN THE WETTER DIRECTION.

SO...THE QUESTION THEN BECOMES ONE OF PRECIP TYPE. ALL THE ABOVE
MODELS SHOW THAT THIS WILL BE A CLOSE CALL...WITH TEMPERATURE
PROFILES SUPPORTIVE OF SNOW WITHIN ABOUT 100 MILES OF WHERE THE
DEEPEST MOISTURE IS. THAT`S CLOSE ENOUGH FOR ME AT THIS POINT...AS
FAR AS INCLUDING A CHANCE OF SNOW IN THE FORECAST FOR FRIDAY NIGHT.
NOW...I AM NOT SAYING FOR SURE IT IS GOING TO SNOW. AND IF YOU TAKE
THE GFS MODEL AT FACE VALUE...ONE WOULD BE LED TO BELIEVE IT WOULD
BE TOO WARM TO SNOW AT ALL. BUT I DO THINK THE COLD AIR IS CLOSE
ENOUGH TO AT LEAST BE A CONCERN...AND WARRANT ITS INCLUSION IN THE
FORECAST. WILL GO WITH CATEGORICAL POPS FRIDAY NIGHT (90%). WILL
WORD IT AS RAIN WITH A CHANCE OF SNOW FROM ALICEVILLE...CALERA...
AND ROANOKE NORTHWARD...AND JUST RAIN SOUTH OF THERE.

GFS INDICATES SOME WRAPAROUND MOISTURE LINGERING IN THE NORTH HALF
OF THE STATE THROUGH THE DAY ON SATURDAY. BY THAT TIME...ITS A
PRETTY SAFE BET THAT ANY PERCIP AT ALL WILL BE IN THE FORM OF SNOW.
WILL THEREFORE CONTINUE TO INCLUDE A CHANCE OF SNOW IN THE NORTH
INTO SATURDAY. STRONG COLD ADVECTION WILL KEEP TEMPERATURES RISING
MUCH AT ALL.

THE FOLLOWING TWO MORNINGS WILL LIKELY BE THE COLDEST WE'VE
EXPERIENCED IN A WHILE...WITH A BIG OL' SURFACE HIGH BUILDING INTO
THE SOUTHEAST STATES. TEENS LOOK LIKELY IN OUTLYING AREAS (PERHAPS
AS LOW AS MIDDLE TEENS).

[Tyler]

Good luck Brent! This event looks promising for you.

[Extremeweatherguy]

DAYS 3-5 ARE FORECASTED TO BE MIGHTY CHILLY AS CANADIAN-BASED COLD AIR
SPILLS INTO EASTERN TEXAS BEHIND FRIDAY`S COLD FRONT. MODELS HAVE
BEEN CONSISTENT IN ADVERTISING THAT DEW POINTS WILL SLAM DOWN
INTO THE LOWER 20S TO UPPER TEENS IN THE FAR NORTH. THIS AIR MASS
WILL BE DRY ENOUGH TO CLEAR SKIES OUT AND LOWER WINDS TO NEAR CALM.
THROW IN THE NICE SHOT OF CAA ALOFT (850 TEMPS IN THE -5 TO -8 C
RANGE WITH 1000-500 MB THICKNESSES IN THE 530 DAMS IN THE NE ZONES)
AND YOUR WEEKEND TEMPS WILL FALL IN THE WELL-BELOW NORMAL LOW TO
MID 50S DURING THE DAY, SUNDAY MORNING THERMOMETER READINGS IN
THE UPPER 20S TO LOWER 30S WELL INLAND, NEAR 40 ALONG THE COAST,
UNDER CRISP CLEAR OVERNIGHT SKIES. IN SUMMARY, THAT WINTER FEELING
RETURNS THIS WEEKEND AS DOES THOSE RISING HEATING COSTS.


^^^Piece of Houston AFD.^^


I still think they are way too warm. Every event I have seen like this in my life ends up never reaching 50 during the day. Also...the overnight lows will be much colder than the upper 20s...especially with the PERFECT radiational cooling conditions they are expecting. We hit 35 at Hooks this morning with 850mb temps. above 0C...so to say that we won't be at least 10 degrees colder under a much more significant system makes no sense. Still no actual forecast out yet...but I have a feeling that they will still not be forecasting as cold as we will be seeing.

[Portastorm]

Meanwhile, we get this snippet of meteorological brilliance (sic) from NWS Austin/San Antonio about the arctic front:

THIS NEXT AIRMASS IS COOL AND DRY. MAX TEMPS WILL BE
NEAR NORMAL WITH OVERNIGHT LOWS FRI NIGHT AND SAT NIGHT BELOW
NORMAL.

As Dr. Smith said in the old "Lost in Space" tv show: "oh the pain ... the pain."

[Tyler]

DAYS 3-5 ARE FORECASTED TO BE MIGHTY CHILLY AS CANADIAN-BASED COLD AIR
SPILLS INTO EASTERN TEXAS BEHIND FRIDAY`S COLD FRONT. MODELS HAVE
BEEN CONSISTENT IN ADVERTISING THAT DEW POINTS WILL SLAM DOWN
INTO THE LOWER 20S TO UPPER TEENS IN THE FAR NORTH. THIS AIR MASS
WILL BE DRY ENOUGH TO CLEAR SKIES OUT AND LOWER WINDS TO NEAR CALM.
THROW IN THE NICE SHOT OF CAA ALOFT (850 TEMPS IN THE -5 TO -8 C
RANGE WITH 1000-500 MB THICKNESSES IN THE 530 DAMS IN THE NE ZONES)
AND YOUR WEEKEND TEMPS WILL FALL IN THE WELL-BELOW NORMAL LOW TO
MID 50S DURING THE DAY, SUNDAY MORNING THERMOMETER READINGS IN
THE UPPER 20S TO LOWER 30S WELL INLAND, NEAR 40 ALONG THE COAST,
UNDER CRISP CLEAR OVERNIGHT SKIES. IN SUMMARY, THAT WINTER FEELING
RETURNS THIS WEEKEND AS DOES THOSE RISING HEATING COSTS.


^^^Piece of Houston AFD.^^


I still think they are way too warm. Every event I have seen like this in my life ends up never reaching 50 during the day. Also...the overnight lows will be much colder than the upper 20s...especially with the PERFECT radiational cooling conditions they are expecting. We hit 35 at Hooks this morning with 850mb temps. above 0C...so to say that we won't be at least 10 degrees colder under a much more significant system makes no sense. Still no actual forecast out yet...but I have a feeling that they will still not be forecasting as cold as we will be seeing.

I strongly agree. Lows around 30 at BUSH!? LOL, its going to be colder than that, by about 5 to 6 degrees. Also, why the heck are mid 50's STILL forecasted!? Again, they are taking MOS guidance verbatim here. They explain how chilly this airmass is, and yet they forecast it like its from the pacific or something. A pro met on another board told me highs would likely not reach 50 saturday, so I have no idea what Houston is talking about.

At any rate, this may be the case where the freaking arctic air has to actually BE in front of their faces (like last December) to see how actually cold its going to be. If you can remember, that day we were stuck in the mid 30's, they forecasted mid 40's the day before. Thats a bust of 10 degrees. Looks like thats about to happen here again folks...

[Extremeweatherguy]

well the NWS is still forecasting 55/29 for Saturday in Spring. It is as if they are taking the models and throwing them out the window. The December system NEVER had 850mb temps. this cold...so to say that this system will be warmer is really quite amazing. -8C 850mb temps. are not seen everyday in Houston and if we were to get that PERFECT radiational cooling which they think we will see...it would not be 29..but instead more like 20. May be the morning shift will put out a better forecast...

[Tyler]

And FYI, 18z GFS is colder than 12z. Model backtracking continues, and we'll likely see some backtracking from the NWS tommorow.

High pressure about 2MB stronger through the cycle.

[Extremeweatherguy]

DAYS 3-5 ARE FORECASTED TO BE MIGHTY CHILLY AS CANADIAN-BASED COLD AIR
SPILLS INTO EASTERN TEXAS BEHIND FRIDAY`S COLD FRONT. MODELS HAVE
BEEN CONSISTENT IN ADVERTISING THAT DEW POINTS WILL SLAM DOWN
INTO THE LOWER 20S TO UPPER TEENS IN THE FAR NORTH. THIS AIR MASS
WILL BE DRY ENOUGH TO CLEAR SKIES OUT AND LOWER WINDS TO NEAR CALM.
THROW IN THE NICE SHOT OF CAA ALOFT (850 TEMPS IN THE -5 TO -8 C
RANGE WITH 1000-500 MB THICKNESSES IN THE 530 DAMS IN THE NE ZONES)
AND YOUR WEEKEND TEMPS WILL FALL IN THE WELL-BELOW NORMAL LOW TO
MID 50S DURING THE DAY, SUNDAY MORNING THERMOMETER READINGS IN
THE UPPER 20S TO LOWER 30S WELL INLAND, NEAR 40 ALONG THE COAST,
UNDER CRISP CLEAR OVERNIGHT SKIES. IN SUMMARY, THAT WINTER FEELING
RETURNS THIS WEEKEND AS DOES THOSE RISING HEATING COSTS.


^^^Piece of Houston AFD.^^


I still think they are way too warm. Every event I have seen like this in my life ends up never reaching 50 during the day. Also...the overnight lows will be much colder than the upper 20s...especially with the PERFECT radiational cooling conditions they are expecting. We hit 35 at Hooks this morning with 850mb temps. above 0C...so to say that we won't be at least 10 degrees colder under a much more significant system makes no sense. Still no actual forecast out yet...but I have a feeling that they will still not be forecasting as cold as we will be seeing.

I strongly agree. Lows around 30 at BUSH!? LOL, its going to be colder than that, by about 5 to 6 degrees. Also, why the heck are mid 50's STILL forecasted!? Again, they are taking MOS guidance verbatim here. They explain how chilly this airmass is, and yet they forecast it like its from the pacific or something. A pro met on another board told me highs would likely not reach 50 saturday, so I have no idea what Houston is talking about.

At any rate, this may be the case where the freaking arctic air has to actually BE in front of their faces (like last December) to see how actually cold its going to be. If you can remember, that day we were stuck in the mid 30's, they forecasted mid 40's the day before. Thats a bust of 10 degrees. Looks like thats about to happen here again folks...

yes. good points. Also, it seems like the afternoon shift of the Houston NWS is always biased warm. May be the morning shift can lower these numbers to where they should be.

[Tyler]

HOLY CRAP. Its a 1055 (yes, that is correct, no typo) over Colorado at 66. Watch out...

5MB stronger than previous run. Backtracking, backtracking, backtracking...