December: New Years Eve Outlook

[Portastorm]

True Ed ... ok, I'm in. I'm officially on the Funderstorm Watch group. Nothing like a little pre-Christmas convective fireworks to get the weather board flowing (with interest, so to speak).

Who knows ... maybe we'll get real lucky and get both: weekend funderstorms and an Arctic Outbreak for New Years.

[MontgomeryCoWx]

Ed... Regardless of whether we play each other, we still battle for recruits daily. It's a concern for both schools and decision makers.


Oh and Happy 30th Anniversary y'all !

http://www.srh.noaa.gov/fwd/?n=dec1983

[TxJohn]

Joe Bastardi posted this

[skidog40]

blues and purples

[Katdaddy]

Bring on the 90s!!!!!!! So ready for Summer again. If its going to get cold, do something productive……SNOW!

[TxJohn]

Are we going to have any sleet potential around Christmas time seeing that it'll be in the mid 30s and a lot of moisture around that time period?

[cperk]

Bring on the 90s!!!!!!! So ready for Summer again. If its going to get cold, do something productive……SNOW!

Katdaddy cool it with that 90's talk.Winter has it's advantages like not having to mow the lawn.

[skidog40]

where is all that Alaskan cold going? If the models get this wrong. look out

[srainhoutx]

It looks like the cap may be too strong for surface based storms to develop as the Euro and Canadian have slowed the cut off upper low a bit and SW flow aloft keeps the cap large and strong across Central and SE Texas via the GFS, but the Euro/Canadian suggest a bit more negative tilt and better dynamics for severe weather and are much 'wetter' and even suggest training showers/storms across Central Texas as a surface low develops. Further N in the cold sector, icy conditions with freezing rain look likely across portions of the Panhandle and Oklahoma and locations further NE. Warm sector heavy training rains may be possible across Arkansas/Tennessee and on E where severe storms have a better chance to develop extending into the SE Region. Another freeze may be possible early next week as well. Late Christmas Day looks changeable as yet another SW upper low approaches from our W and a secondary re enforcing shot of 'colder air' drops S into the Southern Plains on Christmas Eve. It may take another day or two to sort out any severe weather potential for Texas as the short wave that will develop into a robust upper low across Southern California/Baja late Thursday into Friday is further sampled by the RAOB network.



The longer range beyond Christmas Day looks very unsettled with several disturbance crossing our Region and perhaps much colder air drops S from Canada into the Inter Mountain West and Plains and a strong storm system ejects out of Mexico with a noisy sub tropical jet. We will see.

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CST WED DEC 18 2013

VALID 211200Z - 261200Z

...DISCUSSION...
...TX...ARKLATEX...LOWER MS/LOWER OH VALLEY ON SAT/D4...
THE VARIOUS MODELS AND ENSEMBLE MEMBERS ARE IN DECENT AGREEMENT IN
SHOWING THE LOCATION OF GREATEST SEVERE POTENTIAL FROM TX INTO THE
LOWER MS VALLEY ON SAT/D4 AS THE SWRN UPPER LOW/TROUGH EJECTS
RAPIDLY NEWD ALONG WITH A DEVELOPING SURFACE LOW/WAVE ALONG THE
STATIONARY/WARM FRONT. S OF THIS FRONT...AMPLE LOW LEVEL MOISTURE
WILL EXIST WITH MID TO UPPER 60S F DEWPOINTS.

NUMEROUS THUNDERSTORMS SHOULD BE ONGOING ALONG AND N OF A STATIONARY
FRONT EARLY ON SAT/D4...FROM WRN TX NEWD ACROSS THE RED RIVER VALLEY
AND INTO SERN MO...WHERE STRONG WARM AND MOIST ADVECTION WILL EXIST
COURTESY OF A 60 KT SLY LOW LEVEL JET. RAPID COOLING ALOFT...A
VEER/BACK SIGNAL IN THE WIND PROFILE IN THE 850-700 MB LAYER...A
RATHER MERIDIONAL UPPER FLOW REGIME AS WELL AS A SEMI-CAPPED WARM
SECTOR SUGGEST THAT A STRONGLY FORCED QLCS WILL BE LIKELY...CAPABLE
OF DAMAGING WINDS AND A FEW TORNADOES. THE GREATEST THREAT AREA IS
EXPECTED TO BE NEAR THE SURFACE LOW TRACK ALONG THE DEVELOPING WARM
FRONT...OR THE NRN HALF OF THE OUTLOOK AREA.

...SUN/D5 AND BEYOND...
THE SHORTWAVE TROUGH IS FORECAST TO BE LOCATED OVER THE MID MS
VALLEY/LOWER OH VALLEY SUNDAY MORNING WITH LOSS OF AMPLITUDE
COMPARED TO PREVIOUS DAY. AT THE SURFACE...THE COLD FRONT WITH
ONGOING STORMS SHOULD TRAIL APPROXIMATELY FROM IND/OH SWWD ACROSS
TN/AL/MS WITH SOME ONGOING THREAT. GIVEN TIMING ISSUES AS WELL AS
THE LOSS OF THE SHORTWAVE TROUGH TO THE N...WILL DEFER ANY SEVERE
AREAS TO LATER OUTLOOKS. AT THIS TIME...IT APPEARS THE GREATEST
POTENTIAL FOR DAMAGING WINDS AND/OR A FEW TORNADOES WOULD BE ACROSS
ERN MS/AL/GA AND TN IN PROXIMITY TO THE MOST ROBUST MOISTURE AND
MARGINAL INSTABILITY...WITH LINEAR STORM MODE MOST LIKELY.

..JEWELL.. 12/18/2013

[wxman57]

Are we going to have any sleet potential around Christmas time seeing that it'll be in the mid 30s and a lot of moisture around that time period?

No. Wind will be swinging around to the east on Christmas Day, meaning warm advection and steadily increasing Gulf flow.

[srainhoutx]

Morning Update From Jeff:

Cold air mass continues to modify over the region as high pressure slowly shifts eastward allowing defined onshore flow to return to the area.

Fairly widespread radiation fog this morning across the area as temperatures have fallen toward the dewpoints. Should see the fog lift and burn off by mid to late morning and another pleasant December afternoon with highs a few degrees warmer than yesterday or into the low 70’s.

Storm system will dive down the west coast and into the Baja area of MX by late Thursday into Friday and then begin to move eastward toward TX over the weekend. Onshore flow will intensify as low pressure develops across the plains helping to increase southerly winds. Dewpoints will rise into the 60’s by Friday morning and this warm moist air flowing over the cold nearshore waters will promote a good potential for the formation of a dense sea fog bank by Friday. Could see fog begin to form over the waters by late Thursday, but more likely Friday and especially Saturday as dewpoints rise well into the 60’s over water temperatures in the 50’s. Some coastal locations could be fogged in from Friday through most of the day on Saturday with visibilities bouncing around between 1 mile and 1/4th of a mile. Sea fog will spread inland each evening, but how far it penetrates from the coast will be determined by the intensity of the inland wind speeds. Stronger winds will result in a low level cloud deck versus ground level fog with weaker winds supporting more ground level sea fog.

Surface low pressure is spawn over central TX on Saturday as forcing from the parent upper level storm system overspreads the state. Cold front located over N TX at this time will likely stall somewhere near our northern set of counties on Saturday and become the focus for thunderstorm development. Wind shear looks impressive in the forecast soundings over the area with some directional turning with height suggesting updrafts could rotate. Main drawback for widespread strong to severe thunderstorms appears to be marginal instability and potential for warm mid level temperatures or capping aloft. This period will begin to fall into the shorter range model guidance tomorrow which will help define the cap intensity across the region and the chances for convective development. Current thinking is that the main region for strong to severe storms will be across our northern counties into NE TX where mid level temperatures are cooler…but this is still 3 days out and things will likely change some. Best rain chances look to be Saturday afternoon into the late evening hours.

Prior to Saturday increasing moisture advection off the Gulf of Mexico will support a slight chances of light rain showers and drizzle moving inland from late Thursday through all of Friday.

Cold front will sweeps across the area early on Sunday morning ending rain chances and after a few very warm days with highs nearing 80 on Friday and Saturday winter will return to the region with lows falling back into the 30’s by Monday morning and highs in the 50’s under mainly clear skies.

Christmas Outlook:
Looks pretty decent with mainly clear skies and lows in the 30/40’s and highs in the 50’s/lower 60’s.

[unome]

what a gorgeous day it looks to be - great day to tidy up the yard & touch up outside holiday decorations

not having to log in twice made it even better - thanks to whomever is responsible for the fix !

[srainhoutx]

The 12Z GFS suggests a Del Rio/Austin (Hill Country) Texarkana track of the surface low on Saturday and now has a more of a negative tilt ~vs~ an totally open wave at 500mb. Areas along that surface low track will be where the best dynamics and possible erosion of the cap should take place. It does appear there is a sufficient jet streak that may assist breaking the cap. As always, timing and the eventual track will determine where the severe potential will increase.

[TxJohn]

Travis Herzog has a nice little write up on our upcoming weather events.

"Your Christmas forecast is almost here! Christmas Day will officially enter our 7 day forecast this afternoon. My (almost) daily update of what our computer models are showing for Christmas returns today after four refreshing days off with the family. Feel free to share my weather insights with your friends on Facebook because I don't have the time to share most of this on air.

NOTE: This is NOT our forecast - I'm simply relaying what computer projections are showing.

GFS (USA) Computer Model:
This model has trended warmer since my Friday update but still shows it cooling down for Christmas. It brings a round of potentially severe thunderstorms Saturday afternoon as the cold air blows in. The coldest it gets is 32° on Christmas Eve, with a low of 40° Christmas morning. Christmas Day's high gets to 61° with an abundance of sunshine. No White Christmas here.

ECMWF (European) Computer Model:
This computer model is remarkably similar to the GFS. It shows a line of severe storms arriving Saturday evening. The coldest it gets is 31° on Christmas Eve. It's near freezing at 33° Christmas morning with an afternoon high of 60°. No White Christmas here, either.

GEM (Canadian) Computer Model:
Surprise! There's also a Canadian computer model (among many others). You haven't seen this one before because it doesn't go out as far in time as the two above. So consider this a bonus. The Canadian is the coldest of the crop, showing a low of 24° Christmas Eve and 27° Christmas morning. Christmas Day only has a high of 49°. Why is it colder? It shows the arctic high coming straight south toward Texas. Even though it's colder, no wintry precip here, either. Maybe the Canadians know something we don't since the cold air is coming from their country....

My Take:
As I said last Friday, my confidence is growing that we will get another shot of cold air right before Christmas - it's just a question of how cold. And now there's the potential for severe weather on Saturday ahead of the cold front.

While we are certainly seeing a higher level of agreement and consistency from our computer models, I still don't trust them on the details. Our computer models are notorious for performing poorly with the movement of arctic air masses, and I think there is a chance this front will slide in quicker than currently shown, which would undercut the threat for severe weather on Saturday and make the following days colder than projected.


Tomorrow I'll spend more time picking apart the threat for severe weather on Saturday since it will come before the Christmas cool down. Thanks for reading to the bitter end - this turned into a novel! See what happens when I'm off for 4 days?"


How has the Canadian model been doing so far this winter against the Euro and GFS?

[MontgomeryCoWx]

Canadian hasn't done a bad job the past month. It has surprisingly performed well considering its usually the Crazy extra chromosome model of the bunch.

[MontgomeryCoWx]

Something to keep an eye on...

A weak El Nino forming for February onward. That would certainly favor better chances for above average precip. and cooler than average weather. It would be an extra ingredient for some wintry weather in our greatest month, historically, for Winter Weather.

If we could get the EPO back in the tank and pop the PNA, it would be quite the set up from mid winter onward.

[Andrew]

Honestly, to me the severe threat looks extremely marginal in respect to tornadoes. I just feel like the negative tilt transition will be about 12 hours too late in order to get that directional shear that is needed. I do expect we will see a nice line of storms that could have some stronger winds and hail but that looks to be the main aspect of the severe threat. Of course that could change especially with the development of a coastal low east of Corpus. That could provide the low level directional shear that is needed for more discrete cells.

[skidog40]

break that cap

[skidog40]

its like a plug keeping all that cold air up north. I thought cold was going to sweep eastward not happening. Its waiting till the plug is pulled and that's when .....

[Andrew]

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0226 AM CST THU DEC 19 2013

VALID 211200Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE WRN/CNTRL GULF
COAST...ARKLATEX...LOWER MS VALLEY...

...SYNOPSIS...
A VIGOROUS UPPER TROUGH WILL EJECT NEWD FROM THE SRN ROCKIES AND
ACQUIRE A NEGATIVE TILT AS IT CROSSES THE GREAT PLAINS INTO THE
MID-MS VALLEY. A SFC LOW ASSOCIATED WITH THIS FEATURE WILL DEEPEN
OVER CNTRL TX AND TRACK NEWD INTO AR BY LATE AFTERNOON ALONG A
STALLED ANTECEDENT FRONT...BEFORE APPROACHING THE GREAT LAKES BY
EARLY SUN MORNING. A COLD FRONT WILL MOVE EWD OUT OF E TX ACROSS THE
WRN/CNTRL GULF STATES...WHICH IS LIKELY TO BE ACCOMPANIED BY AN
ORGANIZED CONVECTIVE LINE INTO EARLY SUN MORNING.

...PARTS OF THE WRN/CNTRL GULF COAST...ARKLATEX...LOWER MS VALLEY...

CONVECTION IS EXPECTED TO BE ONGOING AT THE START OF THE PERIOD
ALONG A STALLED FRONT EXTENDING FROM CNTRL TX NEWD ACROSS AR TO THE
LOWER MS VALLEY...AIDED BY ISENTROPIC ASCENT ALONG THE NOSE OF A
STRONG LOW-LEVEL JET. MEANWHILE...A SFC LOW IS FORECAST TO DEEPEN AS
IT PROGRESSES NEWD OUT OF CNTRL TX TOWARDS AR...AND AN ATTENDANT
COLD FRONT WILL EXTEND SSEWD. AS DEEP-LAYER FORCING FOR ASCENT
INCREASES VIA MIDLEVEL HEIGHT FALLS/DCVA...ADDITIONAL TSTM
DEVELOPMENT IS LIKELY TO OCCUR ALONG THE COLD FRONT ACROSS E TX BY
EARLY AFTERNOON.

MID-UPPER 60S F DEWPOINTS WILL ALREADY BE IN PLACE EARLY SAT MORNING
THROUGHOUT THE WARM SECTOR. WIDESPREAD CLOUD COVER MAY LIMIT DIURNAL
HEATING AND DESTABILIZATION...BUT RICH BOUNDARY LAYER MOISTURE AND
MODERATE LAPSE RATES WILL LIKELY YIELD MLCAPE VALUES GENERALLY
RANGING FROM 1000-1500 J/KG. FURTHER STRENGTHENING OF THE LOW-LEVEL
JET IS ALSO FORECAST TO OCCUR THROUGHOUT THE DAY...RESULTING IN
ENLARGED HODOGRAPHS. SIGNIFICANT MERIDIONAL COMPONENT TO THE
DEEP-LAYER FLOW COMBINED WITH STRONG LOW-LEVEL FRONTAL CONVERGENCE
AND UPPER FORCING FOR ASCENT WILL LIKELY FAVOR A LINEAR CONVECTIVE
MODE EVOLVING ALONG THE COLD FRONT. THE PRIMARY THREATS ASSOCIATED
WITH THIS LIKELY WILL LIKELY BE DMGG WIND GUSTS AND POSSIBLY A FEW
EMBEDDED TORNADOES. ISOLATED TSTMS MAY ALSO DEVELOP WITHIN THE
PRE-FRONTAL WARM CONVEYOR...WITH DEEP-LAYER SHEAR SUFFICIENT FOR
SUPERCELLS AND A FEW TORNADOES.

LATEST FORECAST MODEL GUIDANCE /NAM IN PARTICULAR/ IS INCONSISTENT
WITH THE SPEED OF THE UPPER TROUGH AND ASSOCIATED SYNOPTIC-SCALE
FEATURES. HOWEVER...THE MOST PROBABLE SCENARIO IS FOR AN MCS TO
EVOLVE AND QUICKLY SPREAD EWD THROUGH THE LOWER MS VALLEY AND ACROSS
TN/MS INTO EARLY SUN. WITH THE PRIMARY SFC LOW AND UPPER TROUGH
PULLING NEWD AWAY FROM THE REGION...INSTABILITY WILL LIKELY DECREASE
WITH EWD EXTENT...BUT SHOULD REMAIN SUFFICIENT TO MAINTAIN
STRONG-SVR WIND GUSTS AND POTENTIALLY AN ISOLATED TORNADO THREAT
OVERNIGHT.

..ROGERS.. 12/19/2013