New Year's Eve Weather

[TexasBreeze]

It's bedtime now. I'm not staying up to see something I can see everyday (clouds).

[biggerbyte]

Complete overcast. No moon to be seen, eclipsed or not.

Bummer!!! I guess we are not allowed to even have that fun either this season.

Oh well.. Winter is just beginning. We'll see what lies ahead, long term.

[Andrew]

I think I am going to move to the west coast or Minnesota. This is depressing weather....

[srainhoutx]

The big question this morning in light of the over night guidance appears to be is the Euro correct with a close Upper Low tracking across TX for Christmas Eve? If it is correct, rain chances would increase across the Lone Star State with the nice return flow that is well established in our area. Also, the cold front does appear to be a rather strong one and the development of an East Coast Winter Storm looks to keep those cool temps in place longer for Christmas Day weekend. Fingers crossed as the pattern suggests some rain chances during the pre New Years Eve time frame as well.

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
902 AM EST TUE DEC 21 2010

VALID 12Z SAT DEC 25 2010 - 12Z TUE DEC 28 2010


...CONTINUED WET ACROSS THE PACIFIC NORTHWEST...
...BELOW NORMAL TEMPS FROM THE PLAINS EASTWARD...
...POTENTIAL EAST COAST WINTER STORM SAT-MON...

THE NORTH ATLANTIC OSCILLATION INDEX REMAINS NEGATIVE THIS MORNING
WITH A LARGE POSITIVE MID-LEVEL HEIGHT ANOMALY EXTENDING FROM
GREENLAND WESTWARD TOWARD HUDSON BAY WHICH IS BLOCKING THE
UPSTREAM FLOW...MUCH OF WHICH IS EXPECTED TO ORIGINATE FROM AN
INTENSE POLAR JET STREAM TRAVERSING THE BASE OF A QUASI-STATIONARY
UPPER CYCLONE OVER THE GULF OF ALASKA THROUGH THE MEDIUM RANGE
PERIOD.

MODEL AGREEMENT WITH THE LARGER-SCALE ASPECTS IS QUITE GOOD TO
BEGIN THE PERIOD. HOWEVER...THIS IS NOT THE CASE OVER THE CENTRAL
CONUS WHERE THE FLOW BEGINS TO SPLIT...WITH THE 00-06Z GFS/00Z
CANADIAN FASTER AND MORE AGGRESSIVE THAN THE 00Z ECMWF/UKMET IN
ALLOWING THE FLOW TO PHASE OVER THE MISSISSIPPI/TENNESSEE VALLEYS
BY DAYS 4/5. SEVERAL ASPECTS...INCLUDING RECENT SATELLITE TRENDS
OVER THE EASTERN PACIFIC SHOWING AN INTENSE POLAR JET TRAVERSING
THE WESTERN PERIPHERY OF AN ACCOMPANYING UPPER TROUGH...HIGHER
SPATIAL RESOLUTION OF THE ECMWF...AND MORE SOPHISTICATED
INITIALIZATION OF THE ECMWF...FAVOR AN ECMWF-LIKE SOLUTION VERSUS
THE 00-06Z GFS...IN ALL AREAS. HOWEVER...GIVEN THAT EVEN THE ECMWF
CAN NOT ACCOUNT FOR UNCERTAINTY IN INITIAL CONDITIONS...FEEL IT IS
MOST PRUDENT TO ADD INCREASING WEIGHT FROM ITS OWN ENSEMBLE MEAN
THROUGH THE ENTIRE PERIOD. THUS...THE UPDATED PRESSURES/FRONTS
WILL BEGIN WITH A 90/10 ECMWF/ECMWF ENSEMBLE MEAN BLEND
RESPECTIVELY DAY 3...WHILE GRADUALLY TRANSITIONING TOWARD A 40/60
ECMWF/ECMWF ENSEMBLE MEAN BLEND RESPECTIVELY BY DAY 7.

REGARDING SIGNIFICANT IMPACTS...THE PACIFIC NORTHWEST EXTENDING
PERHAPS AS FAR SOUTH AS THE SIERRAS WILL REMAIN UNDER THE
INFLUENCE OF AN UNUSUALLY STRONG POLAR JET STREAM EMBEDDED WITH
PERIODS OF HEAVY PRECIPITATION. DAYS 4/5 AND DAYS 6/7 QPF ACROSS
THE WEST ARE EXPECTED TO RANGE BETWEEN 2 AND 5 INCHES POSSIBLY
HIGHER...WITH THE LAST 2 RUNS OF THE ECMWF AND ITS MOST RECENT
ENSEMBLE MEAN USED AS A 1ST GUESS. MEANWHILE...THE EVOLVING TROUGH
OVER THE GREAT LAKES/OHIO VALLEY EARLY IN THE PERIOD FAVOR BELOW
NORMAL TEMPERATURES FOR ALL AREAS FROM THE PLAINS EASTWARD...WITH
SUBFREEZING TEMPERATURES POSSIBLY RETURNING THE ENTIRE GULF COAST
REGION AND MUCH OF FLORIDA BY DAYS 6/7. FINALLY...AN ECMWF-LIKE
SOLUTION FAVORS A WINTER STORM BEGINNING TO DEVELOP NEAR THE
SOUTHEAST COAST BY DAY 4 BEFORE ACCELERATING UP THE EAST COAST
DAYS 5/6. IT IS STILL TOO EARLY TO BE DEFINITIVE WITH THE PRECISE
DETAILS INCLUDING TRACK OF THIS SYSTEM AS MODEL SPREAD CONSIDERING
THE SPLIT-FLOW UPSTREAM BECOMES QUITE LARGE. WHILE THE 00Z ECMWF
IS MOST PREFERRED...MANY OF ITS OWN ENSEMBLE MEMBERS ARE BOTH
FASTER AND SLOWER WITH THE TRACK OF THE LOW WHICH HAS HUGE
IMPLICATIONS FOR THE ENTIRE EAST COAST. THUS...GIVEN THE
UNCERTAINTIES AND SPREAD...THE UPDATED TRACK ALONG THE EAST COAST
WAS MORE HEAVILY WEIGHTED TOWARD ITS OWN ENSEMBLE MEAN ESPECIALLY
LATE IN THE PERIOD.

JAMES

[srainhoutx]

The 12Z NAM suggests a strong trend toward the Euro solution...look at the rain/storms...

[TexasMetBlake]

12z euro shows a massive snowstorm for the south on Christmas Day...

http://www.meteo.psu.edu/~gadomski/ECMW ... floop.html

[srainhoutx]

E-mail from Jeff...

On this the first day on winter, the state will experience near record or record highs in many places.

Zonal flow aloft is helping to keep lower pressures anchored along the front range of the Rockies producing southerly flow across the state. Surface dewpoints have risen into the mid and upper 60’s on SSW winds over the last 24 hours. Dewpoints are running 5-8 degrees warmer than the nearshore water temperatures. Coastal webcams and station observations have yet to show significant sea fog formation as this warm marine air mass spreads across the colder shelf waters. Current thinking is that even with significantly warmer dewpoints over the colder waters, south/south-southwest wind direction is limiting the amount of time of the warm air over the narrow cold water. Additionally wind speeds have been averaging 10-15mph along the coast and this may also be helping in the prevention of dense sea fog.

Winds will weaken this evening and veer toward the SW which will allow a longer fetch moist layer across the length of the nearshore cold waters. Expect that very moist dewpoint air mass will chill to saturation over the cold water and dense sea fog will form right along the coast and the inland bays. Wind direction should keep the fog bank anchored near the coast early and then spreading inland after midnight. Given the large SST/dewpoint spread some very dense fog is possible with visibilities less than ¼ of a mile to near zero right along the coast creating hazardous travel for sea vessels. Not sure how far inland the fog will spread, but locations south of I-10 could be in the soup. Will be hard to break out along the coast with little change in the air mass until Friday. Expect periods of very dense sea fog to spread inland throughout the period.



Other item of interest will be the high temperatures today with records of 81 at IAH possibly being reached or even exceeded if enough breaks in the cloud cover develops. Records for the rest of the week appear out of reach, but it will remain warm and moist until Friday on southerly winds.



Zonal upper air pattern responsible for the warm weather pattern will undergo significant amplification over the western US late this week. Cold air awaiting the right upper air delivery pattern is in place over NW Canada. Polar jet stream will buckle as a large ridge builds over the western US allowing the dislodging of a NW Canada air mass. Strong polar cold front will blast southward down the plains behind a strong upper level storm system over the plains on Friday. Polar air mass will reach TX late Thursday evening and plow across the state on Friday. Significant temperature falls of 10-25 degrees will accompany the front on strong NW winds. NAM model has come in wetter for Friday along with a slightly better chance of rain on the GFS also. Do not feel comfortable going more than 30%, given the stout capping in place and best dynamics passing across N TX, but this would be our first shot at rain since the day after Thanksgiving….we will take whatever we can get at this point.

Cold and dry air mass builds into the region Friday night ending of warm streak. Christmas Day will be clear and cold as polar high pressure builds down the plains. Expect highs in the lower 50’s under NNE winds. Saturday night will be the coldest night with sub-freezing temperatures for most locations and possible mid 20’s across our northern counties. Cold dome will be slow to move eastward unlike the last several cold snap which have lasted 1-2 days. Amplified pattern looks to remain locked in place into early next week keeping the cold air in place into next week. At the surface low pressure is progged to develop out of a western Gulf of Mexico coastal trough come Monday/Tuesday allowing Gulf moist to glide up and over the surface cold dome. It appears rain chances will be on the increase with temperatures holding in the 40’s and 50’s for highs early to mid next week. Not ready to bite yet on the rain potential given the ongoing drought, but it appears this could be our first decent shot at rainfall since early November.

[srainhoutx]

Let snow, let it snow, let it snow...

[sambucol]

Snow??? 'Splain, please!

[srainhoutx]

Fantasy land 18Z GFS is at it again suggesting snow for TX on New Years Day. What does give it some merit is the much discussed pattern change we are seeing. Will it happen? Probably not. But the 'hints' continue of a wetter and cooler pattern after Christmas into the New Year so ya never know.

[sambucol]

You're right about you never know. Just look at the weather events that's going on in Europe and snow in mid-summer in Australia!

[TexasMetBlake]

Where did you hear this at?

[svrwx0503]

http://www.redorbit.com/news/science/19 ... australia/

I heard some people in the office talking about this the other day. I haven't looked at any of the charts, but that must have been one heck of a deep trough!

[srainhoutx]

00Z NAM has started. Let's see what the models spin out tonight...

[srainhoutx]

NAM through 66 hours (beyond my limit, mind you) suggests a wetter storm for Christmas Eve...

[sleetstorm]

It looks like the daytime high for Christmas Day this year is going to be in the middle fifties with a nighttime low in the mid thirties. I will gladly take that, although, it would be even better if the daytime high were to be in the forties, thirties, or even the twenties and if the low were to be in the twenties or teens.

[sambucol]

It looks like the daytime high for Christmas Day this year is going to be in the middle fifties with a nighttime low in the mid thirties. I will gladly take that, although, it would be even better if the daytime high were to be in the forties, thirties, or even the twenties and the low in the twenties or teens.

Ch 13 6pm news this afternoon said the high has been lowered to 48 on Christmas day.

[sleetstorm]

It looks like the daytime high for Christmas Day this year is going to be in the middle fifties with a nighttime low in the mid thirties. I will gladly take that, although, it would be even better if the daytime high were to be in the forties, thirties, or even the twenties and the low in the twenties or teens.

Ch 13 6pm news this afternoon said the high has been lowered to 48 on Christmas day.

What about the morning/nighttime low, sambucol, has Ch 13 news lowered that temperature as well?

[sambucol]

It looks like the daytime high for Christmas Day this year is going to be in the middle fifties with a nighttime low in the mid thirties. I will gladly take that, although, it would be even better if the daytime high were to be in the forties, thirties, or even the twenties and the low in the twenties or teens.

Ch 13 6pm news this afternoon said the high has been lowered to 48 on Christmas day.

What about the morning/nighttime low, sambucol, has Ch 13 news lowered that temperature as well?

I don't recall what the low was. I was excited the high for the day had been lowered!

[srainhoutx]

The GFS is coming in a bit wetter/stronger with the Upper Low. We'll see what the temps will bring...this appears to be a step toward the 12Z Euro solution...