December-Wet/Stormy New Years Eve Ahead

[jasons2k]

Might get very cold next week but I hate to bring some bad news for those hoping for a Christmas miracle - from this morning's NWS AFD:

THOSE WISHING FOR A WHITE CHRISTMAS WILL HAVE TO TRAVEL FAR NORTH OR WEST AS THE PROBABILITY FOR ANY WINTRY PRECIPITATION IS EXTREMELY LOW

[srainhoutx]

SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
355 AM EST WED DEC 19 2012

VALID 12Z WED DEC 19 2012 - 12Z FRI DEC 21 2012

...THE FIRST MAJOR WINTER STORM OF THE SEASON IS GETTING ORGANIZED
OVER THE CENTRAL PLAINS...

...HEAVY SNOW WILL CONTINUE TO IMPACT THE MOUNTAINS OF THE
NORTHWESTERN CONUS...


THE FIRST MAJOR WINTER STORM OF THE SEASON IS IN THE FORECAST FOR
THE CENTRAL PLAINS AND MIDWEST. SHORTWAVE ENERGY TRIGGERING
WIDESPREAD SHOWERS ACROSS THE FOUR CORNER STATES AT THE START OF
THE FORECAST PERIOD WILL SWING OUT INTO THE PLAINS AND HELP
INTENSIFY A SURFACE LOW IN THE LEE OF THE CENTRAL ROCKIES BY
WEDNESDAY AFTERNOON. THE STRENGTHENING CYCLONE WILL QUICKLY TRACK
NORTHEASTWARD TOWARDS THE MIDDLE MISSISSIPPI VALLEY WEDNESDAY
NIGHT AND IS EXPECTED TO REACH SOUTHERN MICHIGAN BY EARLY FRIDAY.
A WELL ORGANIZED BAND OF MODERATE TO HEAVY SNOW SHOULD DEVELOP TO
THE NORTH AND WEST OF THE DEEPENING CYCLONE AND CAUSE A WIDE SWATH
OF GREATER THAN FOUR INCH ACCUMULATIONS FROM THE CENTRAL HIGH
PLAINS NORTHEASTWARD INTO WISCONSIN...WITH EVEN HIGHER AMOUNTS
POSSIBLE ONCE A COMMA-HEAD DEVELOPS ON THE BACK-SIDE OF THE
SURFACE LOW. IN ADDITION...STRONG AND GUSTY WINDS ARE EXPECTED
WITH THIS STORM...AND BLIZZARD WARNINGS HAVE ALREADY BEEN POSTED
OVER THE CENTRAL HIGH PLAINS...WHERE HIGH WINDS AND HEAVY SNOWS
WILL CREATE HAZARDOUS TRAVEL CONDITIONS. WHILE THE DEEP SURFACE
LOW TRACKS NORTHEASTWARD THROUGH THE MIDWEST...A STRONG TRAILING
COLD FRONT WILL SWEEP THROUGH THE SOUTHERN PLAINS ON WEDNESDAY AND
OFF THE SOUTHEAST/MID-ATLANTIC COAST BY FRIDAY MORNING.
INCREASING AMOUNTS OF GULF MOISTURE STREAMING NORTHWARD AHEAD OF
THE FRONT SHOULD HELP FIRE UP CONVECTION ACROSS THE SOUTHERN TIER
AND SOME OF THESE DEVELOPING STORMS MAY BE STRONG OR EVEN SEVERE.

THE NORTHWEST WILL ALSO GET A HEAVY DOSE OF WINTER WEATHER DURING
THE SHORT RANGE PERIOD. AN APPROACHING PACIFIC SYSTEM SHOULD
BRING PLENTY OF MOISTURE ONSHORE..AND THIS...COMBINED WITH FAVORED
OROGRAPHICS...SHOULD DUMP OVER A FOOT OF SNOW OVER THE WASHINGTON
CASCADES ON WEDNESDAY. THE BEST ONSHORE FLOW SHOULD GRADUALLY
SINK SOUTHWARD...SHIFTING THE HEAVIEST COASTAL RAINS AND MOUNTAIN
SNOWS TO SOUTHWESTERN OREGON AND NORTHERN CALIFORNIA ON THURSDAY.


IN THE EAST...ANOTHER DAY OF PRECIPITATION IS IN STORE FOR
NORTHERN NEW ENGLAND ON WEDNESDAY...BUT CONDITIONS SHOULD IMPROVE
ON THURSDAY ONCE A SURFACE LOW OFF THE NORTHEAST COAST PUSHES
FARTHER OFFSHORE.

GERHARDT

[srainhoutx]

The NAM (WRF/NMM) suggest a very potent winter storm today into tomorrow form Colorado and the front range across the Central Plains into the Great Lakes Region laying down some impressive snow totals with blizzard conditions and even thunder snow potential across Iowa into W Illinois.

[gocuse22]

12z GFS backs off of snow big time..

[srainhoutx]

12z GFS backs off of snow big time..

The GFS has flip flopped for 3 runs in a row. These computer models do not have a handle on the energy across the Pacific. That said, the GFS is back to a closed low developing in Eastern Oklahoma heading NE when the 00Z and the 06Z suggested a track across the Tennessee Valley just W of the Appalachians. Another run another solution...check back this weekend...

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
1058 AM EST WED DEC 19 2012

VALID 12Z SAT DEC 22 2012 - 12Z WED DEC 26 2012

THE MEDIUM RANGE PERIOD FEATURES A MODERATELY PROGRESSIVE BUT
ACTIVE PATTERN... CONTINUING TO EMPHASIZE FLOW FROM THE PACIFIC
ACROSS THE CONUS. THIS USUALLY SUPPORTS MILD WEATHER OVER THE
CONUS IN THE MEAN... BUT MID-LATITUDE SYSTEMS WILL HAVE THE
OPPORTUNITY TO TAP SOME COLDER AIR ASSOC WITH AN AREA OF MEAN HIGH
PRESSURE OVER W-CNTRL CANADA. THE NRN/CNTRL PLAINS HAVE THE
HIGHEST POTENTIAL TO SEE SOME OF THIS COLD AIR BY NEXT MON-WED
BEHIND A SYSTEM EXPECTED TO DEVELOP OVER THE E-CNTRL STATES LATE
IN THE PERIOD. EXPECT UNSETTLED WEATHER OVER THE WEST WITH SOME
LOCATIONS OVER THE INTERIOR WEST SEEING A BREAK FOR A PORTION OF
THE FIRST HALF OF NEXT WEEK.

THERE IS REASONABLE MODEL/ENSEMBLE AGREEMENT WITH THE STRONG
WEEKEND SYSTEM TRACKING FROM NEW ENGLAND INTO THE CANADIAN
MARITIMES. HOWEVER SIGNIFICANT DIFFS ARISE FAIRLY EARLY WITH THE
HANDLING OF ENERGY CONTAINED WITHIN A TROF FCST TO ENTER THE WEST
DURING SAT-SUN. THE 06Z GFS/GEFS MEAN AND 00Z UKMET/CANADIAN FORM
ONE RELATIVE CLUSTER WHICH HAS SOME OF THE ENERGY RACING AHEAD AND
SUPPORTING A SFC WAVE WHICH REACHES THE OH VLY/LWR GRTLKS REGION
BY DAY 5 MON. THE 00Z ECMWF AND ECMWF/CANADIAN ENSEMBLE MEANS AND
TO SOME EXTENT 00Z GFS/GEFS MEAN KEEP THE INITIAL WEST COAST TROF
ENERGY MORE CONSOLIDATED AND ARE NOT AS PRONOUNCED WITH SUCH A DAY
5 SFC WAVE.

REGARDLESS OF THE SCENARIO WITH THIS FEATURE THERE IS BETTER
AGREEMENT THAT UPSTREAM FLOW SHOULD EVENTUALLY AMPLIFY INTO A
PLAINS/MS VLY TROF BY DAY 7 WED WITH A POTENTIALLY SIGNIFICANT
STORM SYSTEM TAKING SHAPE OVER OR NEAR THE MS/OH VLY REGION AT
THAT TIME. RECENT ECMWF RUNS HAVE BEEN AGGRESSIVE IN CLOSING OFF
DEEP/CLOSED LOWS ALOFT WHILE THE 00Z ECMWF HAS TRENDED SOMEWHAT
LESS EXTREME WITH THAT IDEA. ON THE OTHER HAND BY DAY 7 THE 00Z
GFS IS ON THE SUPPRESSED SIDE OF THE GUIDANCE SPREAD WITH SFC
EVOLUTION. THE 00Z GEFS/ECMWF MEANS DEPICT A GOOD COMPROMISE
BETWEEN THESE TWO EXTREMES. WILL CONTINUE TO MONITOR THIS SYSTEM
FOR MORE SPECIFIC SNOW/RAIN IMPACTS.

THERE ARE MAINLY TIMING/AMPLITUDE DIFFS WITH THE NEXT TROF IN THE
SERIES FCST TO APPROACH THE WEST COAST BY NEXT WED. RECENT ECMWF
RUNS HAVE TENDED TO BE ON THE SLOWER SIDE OF THE ENVELOPE WHILE
THE 06Z GFS MAY TREND A LITTLE FAST WITH THE SRN PART OF THE TROF
BY LATE NEXT WED. ALSO SOME ECMWF RUNS IN THE 5-7 DAY TIME FRAME
HAVE VERIFIED TOO SLOW WITH FEATURES IN THIS RECENT PATTERN. THE
00Z GFS IS CLOSER TO THE GEFS MEAN WITH THIS TROF.

LOOKING AT THE D+8 MULTI-DAY MEANS... THE MOST AGREEABLE FEATURE
IS A CORE OF POSITIVE HGT ANOMALIES CENTERED ON AVG JUST NE OF
HUDSON BAY. TELECONNECTIONS RELATIVE TO THIS CENTER FAVOR
MODESTLY NEG HGT ANOMALIES OVER THE CONUS WITH BROAD MEAN TROFS
CENTERED OVER THE ERN HALF OF THE CONUS AND OFF THE WEST COAST
NEAR 130W. COMPARED TO THIS RELATIONSHIP THE 00Z ECMWF D+8 COULD
BE TOO DEEP WITH ITS ERN NOAM AND ERN PAC TROFS WHILE THE GFS/GEFS
MEAN MAY NOT EXTEND NEG HGT ANOMALIES FAR ENOUGH WWD INTO THE ERN
PAC. THE 00Z ECMWF ENSEMBLE MEAN D+8 OFFERS THE CLOSEST MATCH TO
TELECON PREFS.


REGARDING PREFS FOR DAYS 3-5 SAT-MON... HPC CONTINUITY HAS THUS
FAR DOWNPLAYED THE SFC WAVE WHICH MAY OR MAY NOT EXIST OVER THE OH
VLY/GRTLKS REGION BY DAY 5 MON. THIS FAVORS THE 00Z ECMWF AND 00Z
ECMWF/GEFS MEANS UNTIL THERE IS FURTHER EVIDENCE TO SUPPORT A
SIGNIFICANT ADJUSTMENT. FARTHER WWD A NEARLY EVEN BLEND OF THOSE
SOLNS LEANS AWAY FROM THE 00Z GFS THAT BECOMES A LITTLE MORE
AMPLIFIED THAN CONSENSUS WITH THE OVERALL TROF ALOFT BY DAY 4 SUN
AND 06Z GFS/GEFS MEAN THAT BECOMES SLIGHTLY FASTER WITH LEADING
HGT FALLS ALREADY ON DAY 3. FOR DAYS 6-7 TUE-WED...
TELECONNECTION PREFS OVER THE CONUS/ERN PAC LATE IN THE PERIOD
FAVOR EMPHASIS ON THE 00Z ECMWF ENSEMBLE MEAN. THE 00Z GEFS MEAN
SFC EVOLUTION IS CLOSE ENOUGH TO ALLOW UP TO 30 PCT WEIGHTING.

RAUSCH

[MontgomeryCoWx]

The 12z GFS can go die in the fiery depths of Hell.

[tireman4]

I am thinking, maybe, by Sunday we may know a little more and see less on the drastic flip flops....

[srainhoutx]

There continues to be a tremendous spread in the GFS Ensembles. There are about half the members that suggest a closed core low developing near the Panhandle with even a couple of members further S and some over Oklahoma. Also the GFS ensembles are somewhat slower to eject the storm system out of our Region, for what it's worth. Also of note via the GFS ensembles is that once the 'cold air' moves in, it will linger right through the Holiday period into near the New Year with an active storm track continuing.

[srainhoutx]

The operational euro is going to be further S this run. Flip flopping along...

Hour 144:

Hour 168:

Hour 192:

[srainhoutx]

This is about a good of a blocking regime as we can see across Canada and bodes well for the Winter weather lover in the Plains and across our Region. It could be very chilly the week leading up to the New Year 'round these parts'...if the trends continue...

[wxman57]

The 12z GFS can go die in the fiery depths of Hell.

I don't think any model has it "right" for next week yet. From this far out, view each model run as a piece of the puzzle - not THE solution. My thoughts when I saw the GFS run were "hmm, it's 30 degrees warmer for next week vs. earlier runs and no snow for TX". That's great for me, but I don't believe it. By Saturday/Sunday I expect good model agreement and a good idea where/when any snow may fall and how cold it will get here.

[MontgomeryCoWx]

I realize its a long shot to get snow down here, but I am praying for some true blue Winter temps. I hate this 70-80 degree crap in Winter.

[tireman4]

Meanwhile, KIAH has hit 81 degrees. The record high temperature for December 19, 2012 is 81. Lovely. Lovely. My run will be just great. Sigh....

[srainhoutx]

One heck of a dust storm ongoing across W Texas and the Panhandle at this hour as the potent Winter Storm ejects from the front range with very heavy snow falling over portions on NW Kansas and Nebraska...

[harpman]

Hey, guys, I'm your neighbor to the east in New Orleans. Love this forum and the good info and characters who post here. (A_Z). I always follow this forum in the winter because usually what Houston gets, we get the next day. (2004 and 2008). Let's hope before the winter is over we all get some love from the winter weather gods!

[srainhoutx]

Harpman, we are making every effort to include you folks to our E in the discussions as well as those in New Mexico and Oklahoma. We are steadily moving toward a more Regional Weather Forum as we continue to grow and have many members well beyond Texas. The inputs from our Pro Mets and very knowledgeable members have caught the attention of folks across the Country including the Media. We know that CNN and TWC follow are postings rather closely as well as others so we encourage our neighbors to become more active. Looking ahead to January, the latest CPC Update certainly suggests a much 'colder' regime may well be ahead for our region and much of the CONUS. We will see.

8-14 DAY OUTLOOK FOR DEC 27, 2012 - JAN 02, 2013

THE GFS AND ECMWF ENSEMBLE MEANS REMAIN IN GOOD AGREEMENT ON THE LONGWAVE
PATTERN, WHICH IS SIMILAR TO THE 6-10 DAY PERIOD. THE ECMWF ENSEMBLE MEMBERS
CONTINUE TO EXHIBIT LOW SPREAD IN AGREEING UPON BELOW NORMAL 500-HPA HEIGHTS
ACROSS THE CONUS, WITH LARGER SPREAD ON THE WEST COAST. HIGH-LATITUDE, POSITIVE
HEIGHT ANOMALIES OVER NORTH AMERICA SEEM TO BE THE DOMINANT FEATURE,
TELECONNECTING TO SLIGHTLY LOWER THAN NORMAL HEIGHTS OVER MOST OF THE CONUS.

ABOVE-MEDIAN PRECIPITATION PROBABILITIES REMAIN HIGH OVER MOST OF THE CONUS,
WITH VERY LITTLE CHANGE FROM YESTERDAY'S FORECAST DUE TO AN ACTIVE STORM TRACK.
SOME TENDENCY TOWARD BELOW-MEDIAN PRECIPITATION IS FORECAST FOR THE FAR
NORTHWEST AS THE STORM TRACK SLIPS SOUTH. THE TEMPERATURE FORECAST REMAINS MORE
UNCERTAIN, ESPECIALLY EAST OF THE MISSISSIPPI RIVER. THE FORECAST IN THE EAST
FAVORS A TENDENCY FOR BELOW NORMAL TEMPERATURES IN PARTS OF THE SOUTHEAST.
BELOW NORMAL TEMPERATURES ARE ALSO FAVORED FROM THE NORTHERN ROCKIES TO THE
CENTRAL CONUS AND ALONG THE WEST COAST WHERE UPPER-LEVEL HEIGHTS ARE EXPECTED
TO REMAIN SIGNIFICANTLY BELOW NORMAL AND ARCTIC HIGH PRESSURE FROM THE NORTH
BECOMES AN IMPORTANT FACTOR. HOWEVER, INCREASED ENSEMBLE SPREAD IN THE
GEOPOTENTIAL HEIGHT FORECAST REDUCES CONFIDENCE ALONG THE WEST COAST.

THE ENSEMBLES HAVE COME INTO GOOD AGREEMENT ON HEIGHT RISES ACROSS NEARLY THE
ENTIRE NORTHERN TIER OF NORTH AMERICA, INCLUDING EASTERN ALASKA AND WESTERN
CANADA. WARMER THAN NORMAL TEMPERATURES ARE FAVORED OVER THE WESTERN PART OF
ALASKA IN RESPONSE TO THIS. RISING HEIGHTS OVER ALASKA POINT TOWARD A BETTER
CHANCE OF CONTINENTAL AIR IMPACTING THE CONUS, FIRST IN THE NORTHERN ROCKIES. TELECONNECTIONS BASED ON THE POSITIVE HEIGHT CENTER JUST NORTH OF HUDSON BAY
ARE NOT IN GOOD AGREEMENT WITH THE HEIGHT FORECAST FROM ANALOGS. SINCE THE
PATTERN CORRELATION BETWEEN THE ANALOG BLEND AND THE MANUAL BLEND IS VERY HIGH,
THIS SUGGESTS THAT THE WEEK-2 PATTERN MIGHT BE TRANSIENT, WITH A POTENTIAL
REALIGNMENT TOWARD A MORE CANONICALLY NEGATIVE AO PATTERN THEREAFTER. WITH A
PERSISTENTLY NEGATIVE AO, THE OBSERVED SURFACE HYDROCLIMATE THIS MONTH REMAINS
UNUSUAL, PERHAPS UNPRECEDENTED. FURTHER COMPLICATING THE EXTENDED RANGE
FORECAST IS THE LACK OF ROBUST TROPICAL CONVECTION ASSOCIATED WITH THE MJO,
WHICH HAS BEEN LARGELY INACTIVE FOR THE PAST MONTH, AND IS ONLY NOW SHOWING
POTENTIAL SIGNS OF WEAK REORGANIZATION.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 10 PERCENT OF TODAY'S
OPERATIONAL 0Z GFS CENTERED ON DAY 11...10 PERCENT OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 11...15 PERCENT OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON
DAY 11...15 PERCENT OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 11...AND 50
PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE
TO HIGH UNCERTAINTY ASSOCIATED WITH A SUPPRESSED ZONAL FLOW, LARGE DISAGREEMENT
AMONG FORECAST TOOLS, AND PERSISTENTLY POOR MODEL PERFORMANCE.

[Portastorm]

I realize this is about weather in the other corner of the state ... but yes, there is one amazing dust storm occuring right now in the Panhandle and South Plains. Interstate 27 between Lubbock and Amarillo has been closed due to "dangerous conditions" per TxDOT. I have some friends up there as well and one texted me "the wind is blowing like 700 mph." I appreciate the hyperbole but it captures the essence of the message!

A lot of energy associated with this system. We're expecting strong winds here in south central Texas when the front passes late this evening.

[MontgomeryCoWx]

Give me a Dec 18-Dec 30, 1983 or Dec 23 to Jan 1, 1989 cold outbreak and I'll shut up for the rest of Winter!

[MontgomeryCoWx]

I realize this is about weather in the other corner of the state ... but yes, there is one amazing dust storm occuring right now in the Panhandle and South Plains. Interstate 27 between Lubbock and Amarillo has been closed due to "dangerous conditions" per TxDOT. I have some friends up there as well and one texted me "the wind is blowing like 700 mph." I appreciate the hyperbole but it captures the essence of the message!

A lot of energy associated with this system. We're expecting strong winds here in south central Texas when the front passes late this evening.

It is snowing its balls off BLIZZNAM style in CO, Nebraska and NW Kansas

[harpman]

Thank you. I appreciate the aknowledgement. We in New Orleans are in the same boat as you folks in Houston when it comes to winter weather. We both see it very rarely! Any mention of it gets lots of us excited and following the model runs religiously. Thanks again!