Rain, snow, and possible severe threats through next week

[OKpowdah]

Two significant shortwaves are forecast to impact the southern Plains over the next 6 days. The first one opens up the Gulf, with a stream of moisture returning to the region. The second wave is even more potent than the first. One of the favorable pattern characteristics here is some degree of blocking over the Northeast ... mostly transient to start, but the first shortwave helps increase downstream blocking ahead of the second shortwave which is why it can amplify so much at a low latitude.

As some of us noted a few days ago on the ECMWF, the set up is a little bit familiar from spring severe weather outbreaks ... it's just a lot colder right now ... Anyway, I think some areas could at least get beneficial rain from these two disturbances.

The moisture return with the first shortwave. PWATs 3-4sd above normal in OK!

The second shortwave

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0355 AM CST TUE DEC 11 2012

VALID 141200Z - 191200Z

...DISCUSSION...

ALTHOUGH MODEST SPREAD PERSISTS AMONG THE VARIOUS MODEL ENSEMBLE

DATA...CONFIDENCE IN THE DEVELOPMENT AND TRACK OF A SIGNIFICANT

SURFACE CYCLONE ACROSS THE CENTRAL PLAINS TOWARD THE GREAT LAKES

REGION THIS COMING FRIDAY/SATURDAY IS FAIRLY HIGH. HOWEVER...AT

LEAST IN PART DUE TO SIGNIFICANT GULF MOISTURE ONLY BEING IN THE

PROCESS OF RETURNING AS THE SYSTEM EVOLVES... JUXTAPOSITION OF THE

MORE FAVORABLE FORCING FOR UPWARD VERTICAL MOTION AND WARM SECTOR

BOUNDARY LAYER DESTABILIZATION REMAINS FAR FROM CERTAIN. EVEN

SO...THE RISK FOR SEVERE STORMS MAY NOT BE OUT OF THE

QUESTION...PARTICULARLY IN A CORRIDOR FROM WEST CENTRAL THROUGH

NORTHERN TEXAS AND PARTS OF SOUTHERN OKLAHOMA LATE FRIDAY...THROUGH

ARKANSAS/NORTHERN MISSISSIPPI/NORTHERN ALABAMA AND WESTERN MIDDLE

TENNESSEE BY LATE SATURDAY. HOWEVER...THE MAIN IMPACT OF THIS WAVE

MAY BE TO HELP ESTABLISH SUFFICIENT MOISTENING...ACROSS THE

WESTERN/NORTHERN GULF OF MEXICO AND GULF COAST REGION...TO

CONTRIBUTE TO A MORE SIGNIFICANT SEVERE THREAT WITH THE NEXT

VIGOROUS SHORT WAVE IMPULSE...WHICH MAY SUPPORT STRONG SURFACE

CYCLOGENESIS ACROSS THE SOUTH CENTRAL U.S. NEXT MONDAY/TUESDAY. THE

SPREAD AMONG THE MEDIUM RANGE MODELS AND ENSEMBLE DATA...THOUGH...IS

STILL MUCH TOO LARGE TO CONFIDENTLY ASCERTAIN THE POTENTIAL FOR A

REGION SEVERE WEATHER EVENT...AND GRAPHICALLY DELINEATE AN AREA.

..KERR.. 12/11/2012

[Srain]

Sam, you may want to amend the title a bit since it appears there will also be some higher elevation snow across CA, NV, AZ and NM during this progressive pattern...this is certainly much different than what we experienced last late fall/early winter across the Southern Rockies/Southern Plains.

ABQ:

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL STRENGTHEN AS IT DIVES

SOUTHWARD ALONG THE CA COASTLINE WEDNESDAY NIGHT. THE SYSTEM WILL

THEN EJECT EASTWARD FROM SOUTHERN CA THURSDAY AND LIFT

NORTHEASTWARD FROM W CENTRAL TO NE NM THURSDAY NIGHT THROUGH

FRIDAY NIGHT WITH A CHANCE FOR PRECIPITATION AREAWIDE. THE HIGHEST

PRECIPITATION PROBABILITIES WILL BE FOUND IN THE MOUNTAINS AND

ALONG THE CONTINENTAL DIVIDE REGION. THE GILA WILDERNESS REGION

COULD BE THE BIGGEST LIQUID WATER EQUIVALENT WINNER WITH UP TO 1

INCH POSSIBLE. THE AMOUNT OF SNOW THAT THIS PACIFIC STORM SYSTEM

PRODUCES WILL DEPEND ON THE TIMING OF ARRIVAL OF A SURFACE COLD

FRONT...WHICH IS CURRENTLY EXPECTED TO CROSS WESTERN AND CENTRAL

AREAS DURING THE DAY FRIDAY. IT MAY NOT CROSS THE PLAINS UNTIL

FRIDAY NIGHT. THE POTENTIAL EXISTS FOR SEVERAL INCHES OF SNOW

ABOVE 7500 FEET OR SO...WITH A FEW INCHES AT LOWER ELEVATIONS

ALONG AND WEST OF THE CONTINENTAL DIVIDE. THE LOWER CHAMA AND

UPPER RIO GRANDE RIVER VALLEYS MAY ALSO BENEFIT FROM A FEW INCHES

OF SNOW. IF THE UPPER LEVEL SYSTEM SLOWS DOWN AND/OR THE SURFACE

COLD FRONT SPEEDS UP...ACCUMULATING SNOW MAY BECOME MORE

WIDESPREAD. WILL CONTINUE THE SPS WE HAVE DISCUSSING THIS SYSTEM.

THE ECMWF AND ESPECIALLY THE GFS SUGGEST AN UPPER LEVEL TROUGH

WILL CROSS NORTHERN NM QUICKLY ON THE HEELS OF THE FIRST WITH A

CONTINUATION OF WINTRY WEATHER ACROSS NORTH CENTRAL AND NORTHWEST

AREAS. THE PRECIPITATION SHOULD NOT BE AS HEAVY AS WITH THE

THURSDAY NIGHT THROUGH FRIDAY NIGHT SYSTEM...BUT TEMPERATURES

SHOULD BE COLD ENOUGH FOR SNOW AT ALL ELEVATIONS. AFTER A BRIEF

BREAK IN THE WEATHER SUNDAY...THE GFS AND ECMWF AGREE ON ANOTHER

UPPER TROUGH PASSING QUICKLY SOUTHEASTWARD ACROSS THE FORECAST

AREA SUNDAY NIGHT AND MONDAY. THIS THIRD SYSTEM SHOULD FORM A

CLOSED LOW OVER NE NM AS IT CROSSES...AND THIS COULD PROVE

FRUITFUL FOR SNOW ACCUMULATIONS AND STRONG WINDS WITH A SURFACE

POTENT COLD FRONT ACROSS THE NORTHEAST QUARTER OF THE STATE.

[OKpowdah]

Sam, you may want to amend the title a bit since it appears there will also be some higher elevation snow across CA, NV, AZ and NM during this progressive pattern...this is certainly much different than what we experienced last late fall/early winter across the Southern Rockies/Southern Plains.

ABQ:

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL STRENGTHEN AS IT DIVES

SOUTHWARD ALONG THE CA COASTLINE WEDNESDAY NIGHT. THE SYSTEM WILL

THEN EJECT EASTWARD FROM SOUTHERN CA THURSDAY AND LIFT

NORTHEASTWARD FROM W CENTRAL TO NE NM THURSDAY NIGHT THROUGH

FRIDAY NIGHT WITH A CHANCE FOR PRECIPITATION AREAWIDE. THE HIGHEST

PRECIPITATION PROBABILITIES WILL BE FOUND IN THE MOUNTAINS AND

ALONG THE CONTINENTAL DIVIDE REGION. THE GILA WILDERNESS REGION

COULD BE THE BIGGEST LIQUID WATER EQUIVALENT WINNER WITH UP TO 1

INCH POSSIBLE. THE AMOUNT OF SNOW THAT THIS PACIFIC STORM SYSTEM

PRODUCES WILL DEPEND ON THE TIMING OF ARRIVAL OF A SURFACE COLD

FRONT...WHICH IS CURRENTLY EXPECTED TO CROSS WESTERN AND CENTRAL

AREAS DURING THE DAY FRIDAY. IT MAY NOT CROSS THE PLAINS UNTIL

FRIDAY NIGHT. THE POTENTIAL EXISTS FOR SEVERAL INCHES OF SNOW

ABOVE 7500 FEET OR SO...WITH A FEW INCHES AT LOWER ELEVATIONS

ALONG AND WEST OF THE CONTINENTAL DIVIDE. THE LOWER CHAMA AND

UPPER RIO GRANDE RIVER VALLEYS MAY ALSO BENEFIT FROM A FEW INCHES

OF SNOW. IF THE UPPER LEVEL SYSTEM SLOWS DOWN AND/OR THE SURFACE

COLD FRONT SPEEDS UP...ACCUMULATING SNOW MAY BECOME MORE

WIDESPREAD. WILL CONTINUE THE SPS WE HAVE DISCUSSING THIS SYSTEM.

THE ECMWF AND ESPECIALLY THE GFS SUGGEST AN UPPER LEVEL TROUGH

WILL CROSS NORTHERN NM QUICKLY ON THE HEELS OF THE FIRST WITH A

CONTINUATION OF WINTRY WEATHER ACROSS NORTH CENTRAL AND NORTHWEST

AREAS. THE PRECIPITATION SHOULD NOT BE AS HEAVY AS WITH THE

THURSDAY NIGHT THROUGH FRIDAY NIGHT SYSTEM...BUT TEMPERATURES

SHOULD BE COLD ENOUGH FOR SNOW AT ALL ELEVATIONS. AFTER A BRIEF

BREAK IN THE WEATHER SUNDAY...THE GFS AND ECMWF AGREE ON ANOTHER

UPPER TROUGH PASSING QUICKLY SOUTHEASTWARD ACROSS THE FORECAST

AREA SUNDAY NIGHT AND MONDAY. THIS THIRD SYSTEM SHOULD FORM A

CLOSED LOW OVER NE NM AS IT CROSSES...AND THIS COULD PROVE

FRUITFUL FOR SNOW ACCUMULATIONS AND STRONG WINDS WITH A SURFACE

POTENT COLD FRONT ACROSS THE NORTHEAST QUARTER OF THE STATE.

Done! Looks like a very impressive pattern ahead, that promises to be active for much of the CONUS. Troughs in both the west and east, with a blocking ridge setting up over eastern Canada

[Buckeye05]

...SOUTHERN PLAINS INTO PARTS OF THE OZARK PLATEAU...

GUIDANCE REMAINS SUGGESTIVE THAT THE LACK OF BETTER PHASING BETWEEN

MID/UPPER FORCING FOR UPWARD VERTICAL MOTION AND BOUNDARY LAYER

DESTABILIZATION WILL HINDER THE RISK FOR SEVERE STORM DEVELOPMENT.

MID/UPPER 50S DEW POINTS MAY ONLY ADVECT AS FAR NORTH AS

SOUTHWESTERN OKLAHOMA/NORTHWEST TEXAS PORTIONS OF A DEVELOPING DRY

LINE BY EARLY FRIDAY EVENING...WHEN 60F+ SURFACE DEW POINTS MAY BE

IN THE PROCESS OF DEVELOPING NORTHWARD INTO CENTRAL TEXAS. THIS

APPEARS LIKELY TO BE GENERALLY SOUTH OF THE AXIS OF THE CYCLONIC

MID-LEVEL JET STREAK AS IT NOSES INTO THE SOUTH CENTRAL PLAINS.

HOWEVER...MOISTURE RETURN/DESTABILIZATION AND LIFT ABOVE A RESIDUAL

COOL/STABLE NEAR SURFACE LAYER IS EXPECTED TO SUPPORT ELEVATED STORM

DEVELOPMENT...WHICH COULD BE BECOME CAPABLE OF PRODUCING MARGINALLY

SEVERE HAIL...GENERALLY NORTH OF THE RED RIVER...ACROSS

OKLAHOMA...BEFORE SPREADING INTO ARKANSAS OVERNIGHT.

FARTHER SOUTH...IT MAY NOT BE OUT OF THE QUESTION THAT CONTINUED

NORTHWARD ADVECTION OF BOUNDARY LAYER MOISTURE...AND LIFT ASSOCIATED

WITH LOW-LEVEL WARM ADVECTION...COULD SUPPORT BOUNDARY LAYER BASED

OR NEAR BOUNDARY LAYER BASED STORM DEVELOPMENT ACROSS PARTS OF

NORTHERN TEXAS OVERNIGHT. IF THIS OCCURS...VERTICAL SHEAR WILL BE

MORE THAN SUFFICIENT FOR SUPERCELLS.

..KERR.. 12/12/2012

[brettjrob]

Shear profiles look mighty impressive for south Texas, but the NAM has really backed off on instability over the past few runs.

[Srain]

SHORT RANGE FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

316 AM EST THU DEC 13 2012

VALID 12Z THU DEC 13 2012 - 12Z SAT DEC 15 2012

...A COMPLEX STORM TO DEVELOP OVER THE SOUTHWEST...

...TEMPERATURES WILL BE 10 T0 15 DEGREES ABOVE AVERAGE FROM THE

UPPER GREAT LAKES TO THE CENTRAL HIGH PLAINS...

A COMPLEX STORM OVER SOUTHERN CALIFORNIA WILL COME TOGETHER OVER

THE SOUTHWEST AS THE SYSTEM MOVES OUT OVER THE PLAINS BY FRIDAY

EVENING. THE STORM WILL PRODUCE LIGHT TO MODERATE RAIN OVER PARTS

OF SOUTHERN CALIFORNIA THAT WILL ADVANCE EASTWARD TO PARTS OF THE

SOUTHWEST AND NORTHWESTERN MEXICO BY FRIDAY MORNING. SNOW WILL

ALSO DEVELOP OVER THE HIGHER ELEVATIONS OF CALIFORNIA AND THE

GREAT BASIN THAT WILL MOVE EASTWARD TO PARTS OF THE

SOUTHERN/CENTRAL ROCKIES AND THE GREAT BASIN BY FRIDAY EVENING.

BY FRIDAY EVENING AS THE STORM MOVES ONTO THE PLAINS ... RAIN WILL

DEVELOP OVER THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI

VALLEY. SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER PART OF THE

SOUTHERN PLAINS ON FRIDAY EVENING ALSO.

MEANWHILE ... A WEAKENING FRONT WILL MOVE ONSHORE OVER THE PACIFIC

NORTHWEST BY THURSDAY EVENING AND DISSIPATE BY FRIDAY AFTERNOON.

THE SYSTEM WILL PRODUCE COASTAL RAIN AND SNOW AT HIGHER ELEVATIONS

OVER THE NORTHWEST THURSDAY EVENING INTO FRIDAY MORNING. THE RAIN

WILL END BY FRIDAY AFTERNOON WHILE THE SNOW WILL CONTINUE OVER

PARTS OF THE HIGHER ELEVATIONS OF THE NORTHWEST INTO PARTS OF THE

NORTHERN ROCKIES BY FRIDAY EVENING.

ELSEWHERE ... A FRONT OVER THE UPPER GREAT LAKES WILL BE

QUASI-STATIONARY THROUGH FRIDAY. SNOW WILL DEVELOP NEAR THE

BOUNDARY THROUGH EARLY FRIDAY MORNING. MOREOVER ... SNOW WILL

DEVELOP OVER PARTS OF NORTHERN MAINE BY FRIDAY EVENING. IN

ADDITION ... LOW PRESSURE MOVING AWAY FROM THE SOUTHEAST COAST

WILL PRODUCE LIGHT TO MODERATE RAIN ALONG THE CAROLINA COAST

ENDING BY THURSDAY AFTERNOON. SHOWERS AND THUNDERSTORMS WILL

DEVELOP OVER PARTS OF FLORIDA THROUGH THURSDAY NIGHT.

ZIEGENFELDER

[Srain]

The 12Z GFS is suggesting a fairly good hit for the White Mountains as well as Mount Lemmon in AZ and the San Jaun/Jemez/Sangre De Cristo on down to the Sacramento Mountians into the Gila Highlands/Black Range...

[patrick7032]

Shear profiles look mighty impressive for south Texas, but the NAM has really backed off on instability over the past few runs.

I spent part of the shift modifying soundings for north central texas. At all three points that I did...San Angelo...Throckmorton (NE of Abilene)...and Wichita Falls...if you used 71/57 as inital conditions...it gave about 550-660 cape with only 26 inhibition. That would be enough for at least elevated supercells given 0-1 bulk shear of 30-40 kts. 1000-700mb RH plots show ~65% behind the initial moisture surge...so some differential heating is possible. Although I'm not "overly excited"...it certainly bears watching. As a side note I attached an interesting graphic.

[Srain]

SHORT RANGE FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

335 AM EST FRI DEC 14 2012

VALID 12Z FRI DEC 14 2012 - 12Z SUN DEC 16 2012

...A FAST-MOVING LOW PRESSURE SYSTEM IN THE SOUTHWEST WILL CREATE

PERIODS OF HEAVY SHOWERS AND SNOW IN HIGHER ELEVATIONS...

...SHOWERS AND THUNDERSTORMS TO BE EXPECTED THIS WEEKEND IN THE

CENTRAL PLAINS...

THE MAIN STORY OF THE FORECAST IS A MATURE FRONTAL BOUNDARY

SITUATED IN THE SOUTHWEST. CURRENTLY...SCATTERED TO BROKEN

SHOWERS ARE FALLING ALONG AND AROUND THIS BOUNDARY. THIS ACTIVITY

IS EXPECTED TO CONTINUE AT LEAST THROUGH MIDDAY FRIDAY. LOCAL

HEAVY RAINFALL IS POSSIBLE...AND SNOW WILL FALL IN THE HIGHER

ELEVATIONS. LOCAL NATIONAL WEATHER SERVICE OFFICES IN THE

SOUTHWEST HAVE ISSUED WINTER WEATHER ADVISORIES AND WINTER STORM

WARNINGS DUE TO THIS FRONT. ANOTHER FRONTAL BOUNDARY...THOUGH NOT

AS ROBUST...WILL MAKE ITS WAY OVER LAND IN THE PACIFIC

NORTHWEST...GENERATING SHOWERS AND ALSO SNOW IN THE HIGHER

ELEVATIONS OVERNIGHT AND INTO FRIDAY AFTERNOON.

ONCE THE AFOREMENTIONED SOUTHWEST SYSTEM PUSHES ITS WAY INTO THE

CENTRAL PLAINS...SHOWERS AND THUNDERSTORMS WILL SPREAD ACROSS THE

REGION BY SATURDAY. PRECIPITATION WILL BE WIDESPREAD...AND WINTRY

PRECIPITATION CAN BE EXPECTED ON THE BACK-EDGE OF THE SYSTEM.

DURING SATURDAY MORNING AND INTO THE AFTERNOON...THE PRECIPITATION

WILL MOVE INTO THE MIDWEST. MOST OF THE COVERAGE IN PRECIPITATION

WILL DECREASE BY SATURDAY EVENING.

ONCE AGAIN...ANOTHER FRONT WILL MAKE ITS WAY TOWARDS THE PACIFIC

NORTHWEST AND WILL PRODUCE AT TIMES HEAVY SNOWFALL ESPECIALLY IN

THE CASCADES AND DOWN INTO THE SIERRA MOUNTAINS. SCATTERED TO

BROKEN SHOWERS WILL CONCENTRATE ALONG THE OREGON AND WASHINGTON

COAST.

MEANWHILE...ALL REMAINS QUIET AND STABLE IN THE EAST AS HIGH

PRESSURE CONTINUES TO DOMINATE OVER THE REGION. THE ONLY

EXCEPTION OF THIS WILL BE ALONG THE EAST COAST OF FLORIDA AND UP

INTO THE CAROLINAS...ONSHORE FLOW WILL PROMOTE SHOWERS AND

THUNDERSTORMS.

FANNING

[Srain]

[MnWeatherman]

Tornado Warning just east of Amarillo, TX. Funnel reported in Washburn.

[LocoAko]

One fatality reported with trucks being blown over and there is a tornado report showing up now, as well. 77MPH wind gust west of Lubbock.

[brettjrob]

Damage shots from a friend in Canyon (S of AMA): http://s135.beta.photobucket.com/user/not_a_leader_of_men/library/Dec%2014%202012%20Canyon%20TX%20Storm%20and%20Damage

[Chicago Storm]

That was a nice forced line. Several QLCS-like spin-ups as it pushed through and to the east of the AMA area.

[patrick7032]

It was an interesting event to watch. THE FIRST DECEMBER PANDHANDLE TORNADOES ON RECORD. I would have been up there if not having to be on shift.

http://www.srh.noaa..../?n=dec14storms

NWS AMA FAcebook page has some nice images:

On the attached image the wind speends in the text box were off center as I bumbed the mouse...but when cursored over the area it showed 33 inbound next to 53 outbound at 614 ft. where you see the "kinks".

[Srain]

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1130 AM CST SAT DEC 15 2012

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS SOUTHEAST TX/CENTRAL GULF COAST

STATES...

...SOUTHEAST TX/CENTRAL GULF COAST REGION TO TN VALLEY...

BROAD CYCLONIC UPPER FLOW WILL PREVAIL OVER THE MAJORITY OF THE

CONUS ON SUNDAY. SEVERAL LOW AMPLITUDE DISTURBANCES ALOFT WILL CROSS

THE REGION /AND ADJACENT MIDWEST/ DURING THE PERIOD...BUT MORE

SUBSTANTIAL TROUGH AMPLIFICATION IS EXPECTED TO OCCUR OVER THE

PLAINS/OZARKS SUNDAY NIGHT/EARLY MONDAY.

ISOLATED TO SCATTERED SHOWERS/SOME TSTMS WILL LIKELY BE ONGOING

ACROSS THE REGION EARLY SUNDAY IN ASSOCIATION WITH PERSISTENT WARM

ADVECTION AND A STEADY MOISTURE INFLUX AHEAD OF A FRONT. RELATIVELY

WEAK LAPSE RATES ALOFT AND A LIMITED NORTHWARD MOISTURE

RETURN...ALONG WITH CLOUD COVER/POSSIBLE PRECIPITATION...SHOULD

LIMIT THE DEGREE OF DESTABILIZATION ACROSS THE REGION. EVEN

SO...SOME OF THESE STORMS COULD BECOME SURFACE BASED AS THE BOUNDARY

LAYER WARMS...WITH AT LEAST SOME ISOLATED SEVERE WIND/PERHAPS

TORNADO POTENTIAL.

THE MOST PROBABLE SCENARIO FOR STORM INTENSIFICATION MAY OCCUR

ACROSS PARTS OF SOUTHEAST TX INTO LA/PARTS OF MS SUNDAY AFTERNOON

AND SUNDAY NIGHT/EARLY MONDAY NEAR AN ADVANCING/ACCELERATING COLD

FRONT. SOMEWHAT STRONGER DESTABILIZATION IS LIKELY IN THESE AREAS IN

THE PRESENCE OF A HIGHER THETA-E AIRMASS...WITH THE REGION

INCREASINGLY COMING UNDER THE INFLUENCE OF THE AMPLIFYING UPPER

TROUGH OVER THE PLAINS/OZARKS BY SUNDAY NIGHT. WHERE STORMS DO

INCREASE/MATURE...VERY STRONG DEEP LAYER SOUTHWESTERLY FLOW AND

ASSOCIATED VERTICAL SHEAR OF 50-80 KT /0-6 KM/ WILL SUPPORT

FAST-MOVING LINE SEGMENTS/SOME SUPERCELLS WITH ASSOCIATED POTENTIAL

FOR DAMAGING WIND/ISOLATED TORNADOES.

..GUYER.. 12/15/2012

[Amped]

No daytime heating but judging by 850 winds and temps thre's tornado outbreak potential across the southeast.

[andyhb]

GFS has significant potential around the Ozarks/Northern LA eastward to the MS River on the evening of the 19th and then eastward possibly overnight into the 20th.

[David Reimer]

GFS has significant potential around the Ozarks/Northern LA eastward to the MS River on the evening of the 19th and then eastward possibly overnight into the 20th.

Yes, it certainly does! While I would expect the timing to change a bit, hopefully a tad slower so it might be chase-worthy closer to home in D/FW, that solution would also be problematic for wind/dust/fire in much of western Oklahoma and Texas. This system now has my full attention after today's small threat.

[andyhb]

Well the Euro certainly does as well, the wording for this should increase from the SPC. I'd even go as far as to throw the "o" word out there for the 96 hr prog on the Euro.

CIPS analogs has some impressive company, with 11/15/05, 1/7-8/08 and 11/15-16/89 showing up among them.

[Srain]

Severe Thunderstorm Watch issued for portions of Central/SE/E Texas/Louisiana until 1:00 PM

[Disc]

Just now showing up in the range of the 12z NAM. It looks a little more aggressive with it than the GFS.

12z GFS continues to look nice through Northern LA, Arkansas, and S MO. Instability looks kinda "meh". SPC does have a D4-D5 discussion out for the SE.

[Srain]

Looking ahead to mid week, the 12Z Op GFS suggest a 1052mb Arctic High developing across Canada as heights build in Alaska suggesting a very strong blocking signal and a bit of a cross Polar flow. The model will likely not handle these features well as a potent Winter Storm ejects from the 4 Corners Region and taps into the very chilly air across Western Canada. Stiff N/NW winds behind that Winter Storm should be enough to dislodge a piece of the very cold air over the Yukon Territory bringing it S into the Plains near Christmas.

EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

1059 AM EST SUN DEC 16 2012

VALID 12Z WED DEC 19 2012 - 12Z SUN DEC 23 2012

...A STORMY WINTER PATTERN FOR THE MIDWEST...GREAT LAKES AND

NORTHEAST...

THE 15-12Z AND 16-00Z GEFS/ECMWF ENSEMBLE MEANS REMAIN IN VERY

GOOD LONGWAVE MEDIUM RANGE AGREEMENT THROUGH DAY 5-6 ACROSS THE

CONUS. AN ENERGETIC PACIFIC SYSTEM EJECTS EAST-NORTHEASTWARD

THROUGH THE CENTRAL PLAINS...AND DEEPENS AS IT MIGRATES

NORTHEASTWARD THROUGH THE MIDWEST...GREAT LAKES AND THE NORTHEAST.

THIS SYSTEM (WHAT AMOUNTS TO A BROAD OCCLUSION ON THE SURFACE

GRAPHICS BY DAY 6) OPENS THE DOOR FOR AN APPRECIABLY COLD AND

BLUSTERY NORTHWEST FLOW PATTERN AND HIGH SURFACE PRESSURE TO SURGE

THROUGH THE SOUTHEAST AND THROUGH THE ENTIRE GULF COAST AND

FLORIDA. THIS SYSTEM SETTLES IN CENTRAL QUEBEC BY DAY 6...WITH

SEVERAL EMBEDDED MID-LEVEL WAVES (POSSIBLY AN ALBERTA CLIPPER-TYPE

SYSTEM) TO REINFORCE AND CONTINUE TO GRADUALLY CARVE OUT THE UPPER

TROUGH ACROSS THE GREAT LAKES AND NORTHEAST. THIS PATTERN WILL

YIELD A GENERALLY COLDER AIRMASS IN PLACE EAST OF 95W...INCLUDING

THE NORTHERN HALF OF THE MS VALLEY...THE GREAT

LAKES...NORTHEAST...THE OHIO VALLEY...AND PARTS OF THE NORTHERN

MID ATLANTIC STATES.

THE DAY 6-7 FLOW PATTERN CONTINUES WITH A TROUGH IN THE NORTHEAST

QUARTER OF THE NATION AND A STAGNANT...SLOW-MOVING TROUGH ALONG

THE WEST COAST. A RIDGE DOMINATES THE CENTRAL PORTION OF THE

CONTINENT. THE ECMWF/GEFS MEANS AND THEIR DETERMINISTIC RUNS ARE

PERHAPS A BIT QUICK IN ALLOWING THE BULK OF THIS PACIFIC TROUGH TO

MIGRATE INLAND GIVEN THE CUTOFF NATURE OF THE SURFACE WAVE AND THE

BLOCKY PATTERN DEVELOPING IN THE CANADIAN MARITIMES.

BOTH MEANS ESSENTIALLY KEEP THE CYCLONIC FLOW MAINLY OVER OPEN

WATER AND MAINTAIN A SPLIT-FLOW PATTERN ALOFT ALONG THE WEST

COAST. THIS WOULD GENERALLY KEEP THE SURFACE WAVE MIGRATING

SOUTHWARD ALONG THE CALIFORNIA COAST THEN ATTEMPTING TO COME

ASHORE BENEATH THE SOUTHERN STREAM IN A SPLIT-FLOW SCENARIO.

VOJTESAK

[Srain]

Fairly significant signal via the 12Z GFES of a rather potent storm ejecting from California across the Four Corners and on out into the Plains. Higher elevation snow including the front range are looking a bit better with a severe weather episode across the warm sector for portions of E Texas/Arkansas and Northern Louisiana.

[baroclinic_instability]

Anyone going to start a thread for the leeside cyclone midweek? First legit CO low of the winter...although is isn't 100% classical. This is a central plains to high plains event...including the Front Range.

[andyhb]

Done Baro.