December: New Years Eve Outlook

General Weather Discussions and Analysis
TexasMetBlake
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Yesterday's 00z run of the gfs just isn't reality. It happens, yes, but something that extreme, especially in the 8-10 day timeframe should have been suspect to you right away. I'm guilty of getting excited too but I've learned to temper the excitement because it is nearly ALWAYS met with letdown.
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what about norh texas are they is forecasted to get ice or snow?
cperk
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TxJohn wrote:Well that's a bummer....maybe next winter.
Just like I suspected....nothing but 30 degree cold.

We still have a lot of winter left.
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srainhoutx
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cperk wrote:
TxJohn wrote:Well that's a bummer....maybe next winter.
Just like I suspected....nothing but 30 degree cold.

We still have a lot of winter left.
That we do. It's a long time until early/mid February when we typically have the 'best' chance of winter mischief in SE Texas.
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sambucol, I do not believe it is time to sound any "all clear" message yet. Here's why I think that:

1) Wxman57's adage of never trust a computer model prior to 4-5 days out still rings true. One can look for trends and potential prior to that time but one should never count on it as gospel truth.

2) Wxman57 has noted on the S2K forum that what has caught his eye is that not only have the surface features predicted in the models changed overnight but so has the predicted upper air flow. So, that change for him gives him some confidence that the changes in the models overnight may be on to something. While I agree with him, I still hold on to his old adage about "never trust a model ..." If we're seeing the same thing later tomorrow in the ensembles and deterministic models, then I'll buy it.

3) If one looks at the ensembles you will find a great diversity if predicted outcomes. The individual members are literally all over the map. That tells me that the models are struggling with the pattern and I wouldn't be surprised to see more changes ahead.

4) I was counting the number of acorns squirrels were collecting in my backyard this morning and ... ok, I'm kidding. ;)
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srainhoutx
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Portastorm, I tend to agree. We can see the operational guidance as well as the ensembles are really struggling with the Pacific pattern and those very warm sea surface temperature across the N and NE Pacific. Case in point, the latest 12Z GFS suggests that the Pacific/Gulf of Alaska ridge noses well into Alaska beyond the 192 hour mark and literally folds, or rolls over bask SE into Canada in the longer range. As always, the ensembles offer the best 'guess' at this point beyond the 3-5 day range regarding our sensible weather.
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Portastorm wrote:sambucol, I do not believe it is time to sound any "all clear" message yet. Here's why I think that:

1) Wxman57's adage of never trust a computer model prior to 4-5 days out still rings true. One can look for trends and potential prior to that time but one should never count on it as gospel truth.

2) Wxman57 has noted on the S2K forum that what has caught his eye is that not only have the surface features predicted in the models changed overnight but so has the predicted upper air flow. So, that change for him gives him some confidence that the changes in the models overnight may be on to something. While I agree with him, I still hold on to his old adage about "never trust a model ..." If we're seeing the same thing later tomorrow in the ensembles and deterministic models, then I'll buy it.

3) If one looks at the ensembles you will find a great diversity if predicted outcomes. The individual members are literally all over the map. That tells me that the models are struggling with the pattern and I wouldn't be surprised to see more changes ahead.

4) I was counting the number of acorns squirrels were collecting in my backyard this morning and ... ok, I'm kidding. ;)
Thanks!
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srainhoutx
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The Morning Update from the HPC/WPC clearly shows the level of uncertainty regarding the various computer model solutions and just what effects on the actual sensible weather will be regarding the Arctic front and the various Northern and Southern stream disturbances.

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1100 AM EST SAT DEC 14 2013

VALID 12Z TUE DEC 17 2013 - 12Z SAT DEC 21 2013

...ANOTHER ARCTIC AIRMASS POISED TO DIVE INTO THE NORTHERN PLAINS
LATE NEXT WEEK...


...OVERVIEW AND GUIDANCE PREFERENCES...

ANOTHER SIGNIFICANT PATTERN CHANGE CONTINUES TO BE WELL-ADVERTISED
BY THE MODELS/ENSEMBLES NEXT WEEK AS THE RIDGE/TROUGH ORIENTATION
FLIPS. TREND HAS BEEN TOWARD A MORE SEPARATED/SLOWER/DEEPER
SOUTHERN STREAM SHORTWAVE OR CLOSED LOW DROPPING SOUTHWARD TOWARD
SOUTHERN CALIFORNIA LATE NEXT WEEK AS THE NORTHERN STREAM
MAINTAINS ITS ROBUST NATURE THROUGH CANADA.
THE ECMWF HAS
GENERALLY LED THE WAY WITH THIS FORECAST THOUGH THE GFS IS WITHIN
THE PROVERBIAL BALLPARK. THE GEFS MEAN OFFERED A SLOWER/DEEPER SW
SOLUTION THAN THE ECENS 24 HRS AGO BUT HAS MAINTAINED ITS MEAN
POSITION WHILE THE TREND HAS SEEMINGLY SWUNG PAST IT. ARCTIC AIR
INTRUSIONS CAN OFTEN SINK SOUTHWARD QUICKER THAN WHAT THE MODELS
SUGGEST WHICH ALWAYS COMPLICATES THE FORECAST. A BLEND COMPRISING
A MAJORITY WEIGHTING OF THE 00Z ECMWF/ECENS AND A MINORITY
WEIGHTING OF THE 06Z GEFS/GFS OFFERED A GOOD STARTING POINT
CONSIDERING THE SUBTLE BUT IMPORTANT SENSIBLE WEATHER DIFFERENCES
SEEN AMONG THEM. PREFERRED TO MAINTAIN THE EC CLUSTER CONTINUITY
TAKING LOW PRESSURE INTO THE GREAT LAKES BY FRI/D6 AS THE ARCTIC
EXPRESS PUSHES THROUGH THE HIGH PLAINS. OPTED TO RELY ON A 70/30
ECENS/GEFS BLEND BY FRI-SAT/D6-7... WHICH KEPT A BIT SLOWER
PROGRESSION OF THE NORTHERN STREAM ENERGY THROUGH SOUTHERN
CANADA... AND THUS A BIT SLOWER FRONTAL PROGRESSION IN THE
NORTHEAST THAN THE ECMWF.

...SENSIBLE WEATHER IMPACTS...

COLD FRONT WILL BRING BELOW NORMAL TEMPS TO AREAS IN THE WEST INTO
THE PLAINS AS SOUTHWARD PUSH OF UPPER ENERGY ALLOWS SOME COOLING
ON THE WEST SIDE OF THE DIVIDE... BUT CONCENTRATED TO THE EAST.
ANOMALIES SHOULD BE IN THE 15F TO 25F BELOW NORMAL ACROSS THE
NORTHERN HIGH PLAINS INTO THE UPPER MS VALLEY THU-SAT/D5-7. LAKE
EFFECT SNOWS SHOULD BE THE MAIN FOCUS EARLY IN THE MEDIUM RANGE
BUT THEN AS THE TROUGH DIGS THROUGH THE WEST PRECIP WILL EXPAND
ACROSS THE CONUS. STILL WATCHING THE OH/TN VALLEY BY SAT/D7 FOR
THE POTENTIAL FOR HEAVY RAIN DEPENDING ON HOW QUICKLY THE SOUTHERN
ENERGY EJECTS EASTWARD. WINTER WEATHER CONDITIONS APPEAR LIKELY
FOR THE NORTHERN PLAINS AND GREAT LAKES NORTH OF THE SURFACE
CYCLONE. IN ADDITION... THIS LEAVES PLENTY OF ROOM FOR GULF
MOISTURE TO REGENERATE A SECONDARY PULSE OF OVER-RUNNING
PRECIPITATION ACROSS THE SOUTHERN PLAINS... SOUTHEAST...
APPALACHIANS AND PORTIONS OF THE UPPER OHIO VALLEY/MID ATLANTIC
STATES THROUGH THE END OF DAY 7 ATOP A VERY SHALLOW CANADIAN
SURFACE HIGH
.



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unome
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I was not prepared for this cold wind, I had only glanced at our local forecast & was looking forward to some sunshine

bites :(
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All,models backing away from extreme cold...and freezing temps. Maybe a freeze or 2....well based on what I'm reading. The models are getting a handle on the weather event as they've been consistent for a couple runs now.

I'm no met...but I doubt highly doubt we'll see a swing bck to major cold for us during Christmas.
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I told Santa to bring me 90 degree weather
I mean with all this flip flopping - anything could happen. Right?
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Approaching 70 degree range for Christmas.....chilly! :shock:
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srainhoutx
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TxJohn wrote:Approaching 70 degree range for Christmas.....chilly! :shock:
John, the spread on the GEFS (ensembles) ranges from the Arctic front dropping all the way into S Texas by Friday to the Central Plains. The deterministic or operational GFS is suffering from convective feedback issues and should be taken with a grain of salt even in the medium range much less the longer range.
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srainhoutx
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FINALY...we have clear skies and chilly temperatures this morning across the Region. Temps have dipped below freezing here in NW Harris County this morning , but the sunshine will be welcomed after a long duration of dreary cold days except for last Wednesday when managed to get a brief break albeit chilly. Sub freezing temps are expected again tomorrow morning N and E of Metro Houston and then the moderation begins. Foggy conditions are likely mid week before Major changes develop.

The medium range is looking rather wet and stormy as we head towards later in the week. The operational and ensemble guidance are in somewhat agreement that a very deep trough will drop S into the Baja Region and a robust upper low will develop and slowly begin to move E across Northern Mexico towards Texas. The fly in the ointment aappears to be the potential of a Coastal Low developing along the Lower/Middle Texas Coast on Friday which would tend to favor heavy rainfall and elevated storms, some possibly strong in the warm sector while the Canadian air mass settles S across the Central/Southern Plains. Across the cold sector a variety on Winter Weather may be possible with freezing rain/sleet and snow further N. If the upper low/trough remains closed or stronger, a significant Winter Storm may develop late Friday into Sunday. Once the frontal boundary slips S, over running moisture may be possible next weekend as the trough may linger to our W with SW winds aloft or a warm nose and colder temperatures at the surface. If things develop as the appear as of this morning, this would be the 3rd such event of this kind since just before Thanksgiving so the movie "Ground Hog Day" come to mind. This remains a very complicated and complex forecast and pattern, so expect changes...some possibly very big as even NWS Houston/Galveston stated this morning. Stay Tuned!
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cperk
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srainhoutx wrote:FINALY...we have clear skies and chilly temperatures this morning across the Region. Temps have dipped below freezing here in NW Harris County this morning , but the sunshine will be welcomed after a long duration of dreary cold days except for last Wednesday when managed to get a brief break albeit chilly. Sub freezing temps are expected again tomorrow morning N and E of Metro Houston and then the moderation begins. Foggy conditions are likely mid week before Major changes develop.

The medium range is looking rather wet and stormy as we head towards later in the week. The operational and ensemble guidance are is somewhat agreement that a very deep trough will drop S into the Baja Region and a robust upper low will develop and slowly begin to move E across Northern Mexico towards Texas. The fly in the ointment aappears to be the potential of a Coastal Low developing along the Lower/Middle Texas Coast on Friday which would tend to favor heavy rainfall and elevated storms, some possibly strong in the warm sector while the Canadian air mass settles S across the Central/Southern Plains. Across the cold sector a variety on Winter Weather may be possible with freezing rain/sleet and snow further N. If the upper low/trough remains closed or stronger, a significant Winter Storm may develop late Friday into Sunday. Once the frontal boundary slips S, over running moisture may be possible next weekend as the trough may linger to our W with SW winds aloft or a warm nose and colder temperatures at the surface. If things develop as the appear as of this morning, this would be the 3rd such event of this kind since just before Thanksgiving so the movie "Ground Hog Day" come to mind. This remains a very complicated and complex forecast and pattern, so expect changes...some possibly very big as even NWS Houston/Galveston stated this morning. Stay Tuned!

srainhoutx it worries me when the NWS ends their discussion with stay tuned.
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Here is the relevant discussion (full text at http://forecast.weather.gov/product.php ... glossary=1). As to the "likely large changes," not sure if they are talking about the storm or temperature aspects, or both.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
450 AM CST SUN DEC 15 2013

DISCUSSION...
RIDGE OF HIGH PRESSURE STRETCHES FROM MEXICO ALONG THE 35
CORRIDOR AND SHOULD CONTINUE TO WEAKEN AND EXPAND EAST TODAY AND
TONIGHT WITH THE RIDGE OVERHEAD SUNDAY NIGHT/MONDAY MORNING. WILL
NEED TO KEEP AN EYE OUT FOR FREEZING FOG IN THE NORTHERN COUNTIES
THIS MORNING WITH THE SMALL T/TD SPREADS AND NEAR FREEZING TEMPS.
OTHER THAN SOME CI EXPECTING CLEARING SKIES AND COOL/COLD WEATHER
TO PREVAIL THROUGH TUESDAY. SOME FREEZING TEMPERATURES CAN BE
EXPECTED AGAIN IN THE NORTHEAST COUNTIES TONIGHT. TROUGH AXIS
DEPARTS MONDAY AND NW TO W FLOW ALOFT PREVAILS UNTIL THE NEXT
TROUGH DEEPENS OVER THE WEST COAST ON WEDNESDAY NIGHT. IN TURN
THIS LEADS TO RICHER MOISTURE RETURNING ON SOUTHERLY FLOW
WEDNESDAY AND THURSDAY. SEA FOG SHOULD RETURN AS LONG FETCH FROM
SOUTHERN GULF GETS TAPPED AND DEWPOINTS CLIMB. RAIN CHANCES OR
MORE LIKELY DRIZZLE CHANCES INCREASE THURSDAY WITH ABUNDANT
CLOUDS. FAVORING THE ECMWF SOLUTION WITH A SHARP TROUGH MOVING
INTO THE WESTERN PORTION OF THE STATE FRIDAY NIGHT WHICH SHOULD
PULL A COLD FRONT THROUGH N TX AND POSSIBLY INTO THE NORTHERN
PORTIONS OF THE AREA SATURDAY...MODELS DIFFER AND UNCERTAINTY
ABOUNDS AS TO HOW FAR SOUTH THE FRONT WILL GET. THESE SOLUTIONS
DIFFERENCES EQUATE TO 10 TO 15 DEGREES EASILY IN HIGHS AND LOWS.
HAVE KEPT TEMPERATURES ON THE WARM SIDE FOR NOW AS TROUGH LIFTS
QUICKLY NORTHEAST AND WOULD LEAD TO WARM FRONTOGENESIS EARLY
SATURDAY OVER THE AREA AND THE THREAT OF STRONG THUNDERSTORMS.
WIND PROFILES IN THE ECMWF SOLUTION ARE PACKED TO THE GILLS WITH
WIND AND SHEAR BUT LACK IN CAPE. CHANGES AND LARGE CHANGES AT THAT
ARE LIKELY FOR THIS COMING WEEKEND SO STAY TUNED
.
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wxman57
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Texas Pirate wrote:I told Santa to bring me 90 degree weather
I mean with all this flip flopping - anything could happen. Right?
He'll have to work very hard to fulfill that request. ;-)

Models have backed way off of any extreme cold for SE TX over the past 2 days. It's not just the surface projections, it's the whole upper-level pattern that has changed on the models. I"m looking at the GFS ensemble members now and only a couple of them indicate any freeze in Houston through the 31st. I think we may have a light freeze before Christmas (next Sun or Mon) but don't see any indication of extreme cold near Christmas. Temps should steadily warm all this week - up to the low-mid 70s by Friday. Then the front comes through and drops temps into the 30s with highs in the 40s and 50s.

Interesting discussion from the Houston/Galveston NWS office. They must ONLY be looking at the GFS, as the Euro certainly drives the front through late Saturday and WELL out into the Gulf. I suspect the GFS is incorrect in stalling the cold air over Houston. That's very unlikely. However, the Euro stalls it just north of Houston until early Monday. The nature of the cold air will determine its position. Shallow Arctic air will plunge south through Houston, regardless of the upper air flow.
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tireman4
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And the "Bear Watch" continues............
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It appears the models are even indicating the shallow front may slow/hang up and takes it's time passing, although our history wih shallow arctic air masses and the models from a timing standpoint have been off (slow). Looks like the cold air might not dive straight down the lee side of the Rockies, but rather E/SE instead. As for the "large changes likely" comment in the HGX discussion this morning, maybe they are talking more of a marginal severe weather threat as I've seen some hintings/talks of that as well. As our astute promets put it, these models don't really have a good handle on things until 3-5 days max out. Ensembles are better longer range predictions of the pattern changes, but even they have been anything but consistent. Ensembles had a rather good handle on the Thanksgiving storm as opposed to this upcoming event.

Just my $.02 worth...
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I realize that different models and forecasting services can diverge in their medium and long-range temp forecasts, but I am increasingly frustrated by the inability to get a good handle on the temperatures in the short-term.

For example, our local tv stations, NWS, TWC, and Weather Underground forecast lows for Houston on Monday, Tuesday, and Wednesday as follows (I used a downtown Houston zip code for the NWS, TWC, and Weather Underground forecasts):

Ch. 11: 32, 35, 38 (http://www.khou.com/weather) (using forecast in the video still from this morning at the top of the page)

Ch. 13: 32, 39, 45 (http://abclocal.go.com/ktrk/channel?sec ... id=6650179)

Ch. 2: 34, 38, 45 (http://houston.justweather.com/?default=true)

Ch. 26: 36, 41, 47 (http://www.myfoxhouston.com/weather)

National Weather Service: 42, 47, 57 (http://forecast.weather.gov/MapClick.ph ... q296PRDuJq)

The Weather Channel: 42, 47, 57 (http://www.weather.com/weather/5-day/Ho ... 77002:4:US)

Weather Underground: 44, 46, 57 (http://www.wunderground.com/cgi-bin/fin ... uery=77002)

Even for tomorrow morning, there is anywhere from a 6 to 12 degree difference between our local tv forecasts and the NWS, TWC, and Weather Underground forecasts. Among our local tv forecasts, there is a 7 to 9 degree divergence between Ch. 11 and Ch.'s 2, 13, and 26 for the lows on Wednesday. There is anywhere from a 10 to 19 degree difference between our local tv forecasts and the NWS, TWC, and Weather Underground forecasts for Wednesday! For whatever reason, Ch. 11 is disposed toward the lowest forecasted temperatures of them all.

What gives?
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