December 2016- End Of Year Forecast

[Heat Miser]

Tomorrow you'll be fine to walk if you don't mind a little mist possibly and howling northeast winds blasting you with temps in the 40's.
Was someone saying something about 1983 or 89?
I don't think so, just your typical shot of cold air, hardly freezing in the metro area northward, and a warm up by Saturday.
It's a typical two day event, one I've seen my whole lifetime in this area.
To get an 83 or 89 event that pool of extremely cold air would have to come straight south without much in the way of modification. To get an 83 event you'd need multiple shots for close to a week with daytime highs hardly reaching the freezing mark. Believe Houston remained at or slightly below freezing for five days. I remember the ponds freezing over on the golf course. A trampoline shattering when we jumped on it. Water fountains with large mountainous ice formations around them.
1989 was brutal and driving in it was downright scary. The snow that fell earlier in the day became very powdery later when the clouds parted.
I have never felt that type of cold in my life and haven't felt it since.
Arctic air modified to me really isn't arctic air. Yes, the source region may have originated in the arctic, but it's been worked over so much by Canada and the lower 48 it hardly resembles arctic. Later on when we have snow pack to our north and a flow that's not so zonal, yeah I'll consider it arctic.

[Ptarmigan]

Tomorrow you'll be fine to walk if you don't mind a little mist possibly and howling northeast winds blasting you with temps in the 40's.
Was someone saying something about 1983 or 89?
I don't think so, just your typical shot of cold air, hardly freezing in the metro area northward, and a warm up by Saturday.
It's a typical two day event, one I've seen my whole lifetime in this area.
To get an 83 or 89 event that pool of extremely cold air would have to come straight south without much in the way of modification. To get an 83 event you'd need multiple shots for close to a week with daytime highs hardly reaching the freezing mark. Believe Houston remained at or slightly below freezing for five days. I remember the ponds freezing over on the golf course. A trampoline shattering when we jumped on it. Water fountains with large mountainous ice formations around them.
1989 was brutal and driving in it was downright scary. The snow that fell earlier in the day became very powdery later when the clouds parted.
I have never felt that type of cold in my life and haven't felt it since.
Arctic air modified to me really isn't arctic air. Yes, the source region may have originated in the arctic, but it's been worked over so much by Canada and the lower 48 it hardly resembles arctic. Later on when we have snow pack to our north and a flow that's not so zonal, yeah I'll consider it arctic.

1983 and 1989 came in waves. December 1983 had a negative East Pacific Oscillation (EPO) and West Pacific Oscillation (WPO), but positive North Atlantic Oscillation (NAO). 1989 had negative NAO, EPO, and WPO.

[MontgomeryCoWx]

Oh my wow... that latest GFS run. Let's see if it holds....

[DoctorMu]

Oh my wow... that latest GFS run. Let's see if it holds....

Another freeze on the 15th down to Houston



Another wave of cold air on the 19th as well.

[srainhoutx]

HGX issue Freeze Warning across portions of SE Texas mainly along and North of I-10.

[srainhoutx]

The latest GFS solution continues to raise an eyebrow around mid December and just beyond. Will need to monitor for the potential of a hard freeze around the 15th and a possible wintry weather trouble maker around the 18th is the GFS solutions are correct. Still way too soon to know with any certainty, but we'll be monitoring.

[srainhoutx]

The overnight guidance continues to trend colder next week into the mid December timeframe and just beyond. The upper air pattern continues to move away from the quasi zonal flow across the United States to that of a blocking pattern with a very deep longwave trough developing across the Central United States. If the upper air pattern is correct, some of the coldest air we have seen in several years will invariably drop South out of Canada and the Arctic. We will see.

[snowman65]

I don't see any forecasts anywhere that are biting on that yet. With it only 7 days out, you would think someone would be. But that would be very interesting, indeed...

[unome]

TWC mentions the next wave of arctic air here: https://weather.com/forecast/national/n ... d-december

Next Week's Arctic Blast

Most areas will see temperatures moderate early next week, with the exception of the northern Rockies and northern Plains, which will continue to experience below-average temperatures. However, this reprieve will not last long, as an arctic cold front will push through the Midwest by midweek. High pressure will then build in behind the front, allowing very cold air to infiltrate portions of the U.S.

It does appear that the stratospheric polar vortex is playing a role in the upcoming frigid conditions. The polar vortex is basically a closed circulation surrounding the polar regions in the upper atmosphere, and when it becomes weakened or elongated, a piece of it can surge farther south. The result is arctic cold reaching into parts of Canada.

The details will likely change as we get closer to next week, but here is an overview of what to expect with the next blast of very cold temperatures:

• Temperatures 20 to 35 degrees colder than average are expected in parts of the northern Rockies, northern Plains and upper Mississippi Valley.
  On Wednesday, temperatures 15 to 30 degrees below average will be felt from the northern and central Plains into the Midwest.
  Late next week, very cold conditions will likely spread into the East and possibly portions of the South.
  Highs may only reach single digits for much of the upper Midwest, including Chicago.
  Subzero lows are expected in the northern Plains and upper Midwest, while lows in the single digits and teens will likely be found through the central Plains into the Midwest and interior Northeast.
  Temperatures may not reach the freezing mark late next week from Boston to Philadelphia.

There is some uncertainty in the details, including how cold it will be and how far south the bitter cold will reach. In areas where snow accumulates into early next week, temperatures have the potential to be colder than currently anticipated. Wind chills will be even colder, and a few record cold temperatures cannot be ruled out.

[srainhoutx]

The Weather Predication Center also mentioning the secondary Arctic Air expected next week:

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
149 AM EST THU DEC 08 2016

VALID 12Z SUN DEC 11 2016 - 12Z THU DEC 15 2016

...ARCTIC AIR TO SURGE INTO THE LOWER 48 NEXT WEEK...


...OVERVIEW...

A MIDDLE/UPPER-TROPOSPHERIC CLOSED LOW IS FORECAST TO DROP
SOUTHWARD FROM NUNAVUT THIS WEEKEND AND THEN TURN EASTWARD THROUGH
SOUTHERN CANADA DURING THE MIDDLE OF THE WEEK. A SHORTWAVE
INITIALLY IN THE NORTHERN PACIFIC WILL PASS THROUGH THE INTERIOR
PACIFIC NORTHWEST AND ROCKIES SUNDAY BEFORE AMPLIFYING IN THE
PLAINS AHEAD OF THE CANADIAN UPPER LOW. A BROAD CYCLONIC
CIRCULATION WILL ENCOMPASS THE EASTERN HALF OF THE LOWER 48 BY
NEXT WED/THU WHILE ATTEMPTS TO PUSH INTO THE WESTERN STATES.

...GUIDANCE PREFERENCES...

THE LARGER/SYNOPTIC SCALE FLOW SHOWS GOOD AGREEMENT OUT TO ABOUT
NEXT WEDNESDAY AMONG THE ENSEMBLES. THE BIGGER QUESTION LIES IN
HOW THE PACIFIC SHORTWAVE ZIPS THROUGH THE FLOW ACROSS THE CONUS
NEXT SUN-TUE AHEAD OF THE COLD SURGE FROM THE NORTH. THE MODELS
HAVE NOT BEEN VERY CONSISTENT AND THE ENSEMBLE SIGNAL HAS TRENDED
TOWARD A SLOWER AND MORE AMPLIFIED SOLUTION IN THE ECMWF ENSEMBLES
BUT NOT SO IN THE GEFS ENSEMBLES. GIVEN THAT THE GFS WAS QUICKER
THAN THE ECMWF/UKMET/CANADIAN, OPTED TO SLOW DOWN THE PROGRESSION
OF THE FRONT THROUGH THE CENTRAL STATES SUN-MON AS THE SFC LOW
HEADS TOWARD THE GREAT LAKES. BY TUESDAY THE FRONT IS OFF THE
COAST AND THE ARCTIC SURGE WILL FOLLOW FROM NW TO SE THEREAFTER.
ANOTHER QUESTION LINGERS BY NEXT WEDNESDAY -- CAN THE ARCTIC SURGE
SPIN UP ANOTHER AREA OF LOW PRESSURE ALONG THE FRONT TO SLOW ITS
PROGRESSION EASTWARD NEXT TUE/WED? THOUGH POSSIBLE, DID NOT DEPICT
SUCH A FEATURE AT THIS POINT.

BACK TO THE WEST, A LARGE SPREAD IN ENSEMBLE TEMPERATURES EXPANDS
AROUND THE DIVIDE AS THE COLD AIR ATTEMPTS TO BLEED THROUGH TO THE
WEST AND SOUTH. SECOND TO THAT, BY NEXT THURSDAY THE MODELS
DIVERGE ON HOW QUICKLY TO LIFT THE ARCTIC DRAPE BACK TO THE NORTH
AS A PACIFIC SYSTEM APPROACHES THE AREA. LOTS OF ENSEMBLE SPREAD
LEADS TO LOWER CONFIDENCE, BUT USUALLY THE COLD AIR IS SLOWER TO
ERODE/RETREAT THAN FORECAST.


...WEATHER HIGHLIGHTS/THREATS...

PERSISTENT WEST TO EAST MID-LEVEL FLOW WILL KEEP THE WESTERN
REGION ACTIVE, ESPECIALLY OVER NORTHERN CALIFORNIA NORTHWARD ALONG
THE COASTAL RANGE AND CASCADES. ADDITIONAL UPLIFT VIA THE ARCTIC
BOUNDARY MOVING OUT OF MONTANA WILL PROVIDE ANOTHER MECHANISM FOR
SNOWFALL OVER THE BITTERROOTS AND SAWTOOTH RANGE. GENERALLY ABOVE
AVERAGE TEMPERATURES WILL CONTINUE FOR THE SOUTHWESTERN FIFTH OF
THE CONUS (CA/NV/UT/AZ AND WESTERN CO/NM).

WITH THE FORECAST ARCTIC SURGE COMING OUT OF SOUTHWEST CANADA INTO
THE NORTHERN PLAINS, AN IMPRESSIVE AREA OF WELL BELOW AVERAGE
TEMPERATURES WILL RUSH SOUTHWARD AND EASTWARD FROM THE NORTHERN
HIGH PLAINS THROUGH THE MIDWEST AND EVENTUALLY TO THE EAST COAST
BY WED/THU NEXT WEEK. TEMPERATURES MAY BE 20-30 DEGREES BELOW
AVERAGE AND MAY FLIRT WITH SOME RECORDS (PERHAPS RECORD LOW
MAXIMA) THOUGH THE LONGER PERIOD STATIONS GENERALLY HAVE SOME VERY
COLD RECORDS BY NOW (MID-DECEMBER).

NW FLOW AND COLD AIR OVER THE GREAT LAKES SHOULD SUPPORT A
MULTI-DAY LAKE EFFECT EVENT FROM MICHIGAN EASTWARD THROUGH NE
OHIO/NW PA INTO WESTERN/CENTRAL NY INCLUDING THE TUG HILL PLATEAU.
TRACK OF THE EXITING SFC LOW AND INCOMING SFC HIGH WILL DETERMINE
WHO SEES THE MOST SNOW, BUT SETUP LOOKS GOOD PROVIDED ENOUGH
MOISTURE CAN BE WRUNG OUT IN THE OVERALL DRY/COLD AIRMASS. GLOBAL
MODELS/ENSEMBLES GENERALLY HAVE A GREEN LIGHT FOR AT LEAST
LIGHT-MODERATE SNOW NEXT TUE-THU (AND PERHAPS BEYOND).


FRACASSO

[Heat Miser]

The key will be this.

ANOTHER QUESTION LINGERS BY NEXT WEDNESDAY -- CAN THE ARCTIC SURGE
SPIN UP ANOTHER AREA OF LOW PRESSURE ALONG THE FRONT TO SLOW ITS
PROGRESSION EASTWARD NEXT TUE/WED? THOUGH POSSIBLE, DID NOT DEPICT
SUCH A FEATURE AT THIS POINT.

That in a nutshell tells me that without something to anchor the cold it will do its normal thing and progress eastward quickly, thus saving us from the frigid temps we otherwise would encounter, at least in duration.

[ticka1]

Latest email from Jeff Lindner Thursday morning

Freeze Warning in effect tonight north of a line from Columbus to Spring to Liberty



Wind Advisory in effect until 600pm for area along US 59 south to the coast.



Strong cold front has moved off the coast this morning with a modified arctic air mass pilling into the region. Temperatures at 900am range from the low 40’s at CLL to 55 at GLS with most of the area now having fallen into the 40’s. Strong winds of 20-35mph are in progress over the region with recent gusts of 41mph at Galveston. Winds will likely come up a little bit more around midday with a strong pressure gradient in place. Light rain and drizzle has largely ended over the region, but moisture trapped in the frontal inversion will keep a thick deck of low and mid level clouds in place for much of the day. Temperatures will remain nearly steady in the mid 40’s for much of the day with wind chills in the 30’s.



Tonight:

Not very confident that clouds will clear enough nor winds will relax to get good cooling conditions. With that said the upstream air mass over NC TX is very cold with temperatures in the 30’s and forecasted to fall into the 10’s tonight in this region so even with clouds and some wind tonight expected the surface freeze line to advect into our region. Lows will range from the upper 20’s around the College Station and Huntsville areas to near 31-32 along and north of I-10. This will generally be a light freeze for those areas…but a killing freeze for sensitive growth and an end to the growing season.



Continued cold on Friday even with more sun with highs only reaching about 50. Surface high begins to shift eastward Friday evening allowing weak easterly winds to develop overnight. Think these weak onshore winds will save most of the area from another freeze, but areas NE of Houston closer to the surface high and last to see winds go to the east may drop below freezing. This could be a case where temperatures bottom out around midnight and then start a slow rise.



Warm air advection on Saturday will increase temperatures to near 60 and then 70 on Sunday. Will likely need to bring rain chances back into the forecast Saturday night from SW to NE across the area and on into Sunday. Overall rain amounts look fairly light compared to last weekend.

[DoctorMu]

The latest GFS solution continues to raise an eyebrow around mid December and just beyond. Will need to monitor for the potential of a hard freeze around the 15th and a possible wintry weather trouble maker around the 18th is the GFS solutions are correct. Still way too soon to know with any certainty, but we'll be monitoring.

GFS still has a southern snow even beginning on the 19th in E Texas and LA.






It should be an interesting week of forecast timing.

[unome]

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1007 AM CST Thu Dec 8 2016

.DISCUSSION...
Latest trends in observations show temperatures slowly falling across SE Texas this morning. Much of the area should remain in the 40s with low 50s right along the coast. Windy conditions will continue as will the wind advisory until 6PM. Wind chill values will run in the 30s to low 40s for much of the day making it feel colder. Rain chances should be decreasing through the day along the coast but linger in the offshore waters.

As always determining freezing temperatures in SE Texas is a challenge and this is no different. Couple of factors to consider. First, cloud cover overnight which should be moving east. This will depend upon how quickly a passing shortwave now over the Big Bend moves across Texas. Second, winds should continue overnight so there will not be much decoupling of the boundary layer if any. Third, wet grounds from recent rains could keep the near surface air warmer than if it were dry. This may be a very small contribution. Finally cold air advection will be strong as 850mb freezing line should reach KCLL to KLFK Friday morning.

We will evaluate 12z model guidance before tweaking the Min temp forecast for Friday morning but really do not expect much change. High confidence that areas from Brenham/Conroe/Cleveland will drop below freezing. It will be the area between that line and Columbus/Houston/Liberty that will be a challenge determining if a freeze will occur. Be sure to know that we are only looking at the outlying NW to N areas of Harris County that may experience a brief freeze. The rest of the county will not but due to county based hazards the whole county is in the freeze warning. Also with any precipitation chances ending during the day due to drier air, there will not be any chances of frozen precipitation tonight into Friday morning.

Overpeck

http://www.wrh.noaa.gov/zoa/mwmap.php?map=fwd
http://www.wrh.noaa.gov/zoa/temperature.php?map=zhu
http://www.wrh.noaa.gov/zoa/mwmap2.php? ... on&limit=1

[MontgomeryCoWx]

I know it's day 10 to 15 but that's an impressive cold outbreak over Christmas

[snowman65]

What are you looking at? Can you share a link?

I know it's day 10 to 15 but that's an impressive cold outbreak over Christmas

[MontgomeryCoWx]

What are you looking at? Can you share a link?

I know it's day 10 to 15 but that's an impressive cold outbreak over Christmas

Go to tropicaltidbits.com and click on GFS model. Go to hour 240 and thru 384.

[Heat Miser]

Models are useful in determining possible trends. So many variables in weather that model hugging becomes wish-casting IMO.
Especially 15 days out.

[srainhoutx]

It's always good to remember that the models cannot be trusted as the absolute truth beyond 2-5 days, if then. That said we should monitor the trends and the ensembles to assist in determining what the sensible Hemispheric Pattern may offer. Brrr...it's cold outside.

[srainhoutx]

The afternoon updated Climate Prediction Center Day 8+ Analogs as well as the Day 6 to 10 Temperature Outlook suggests colder weather is here to stay for a while.