Texas Winter 2014-2015

[Portastorm]

The Portastorm Weather Center would like to wish a very Merry Christmas to all on Storm 2K and especially those of you who frequent this thread, whether you're in Texas or somewhere else. We hope you have many moments of peace and happiness tomorrow whatever you end up doing. Y'all are a special bunch!

Now ... back to work and cranking up our winter storm machine for next week ...

[northjaxpro]

Same to you Portastorm! Merry Christmas to you and all of your loved ones!

[Portastorm]

Great discussion out of EWX this afternoon ... Mr. Hampshire came to us from the Fort Worth office and no doubt has some "Cavanaugh" in him. Here's a snippet:

NOW FOR THE MOST INTERESTING PART OF THE FORECAST. AS THIS TROUGH
MOVES OUT SUNDAY...THE NEXT STORM SYSTEM WILL BE TAKING SHAPE
ACROSS THE NORTHWEST CONUS SUNDAY EVENING. A VERY AMPLIFIED RIDGE
AXIS WILL BE EXTENDED OFF THE WESTERN CONUS...NORTH INTO THE
CANADA/ALASKA BORDER WITH 500 HEIGHTS NEAR 570DM REACHING 60 DEGREES
NORTH. THIS IS A STANDARDIZED ANOMALY OF ABOUT ABOUT 3 STANDARD
DEVIATIONS ABOVE NORMAL FOR THAT REGION. TO THE EAST OF THIS RIDGE
AXIS A VERY DEEP TROUGH AXIS IS ABLE TO THEN DIG SOUTHWEST WITH THE
MAIN RIDGE AXIS ORIENTED FROM NEAR NORTH DAKOTA BACK INTO ARIZONA
MONDAY EVENING. THIS UPPER PATTERN IS TYPICALLY KNOWN FOR BRINGING
COLD ARCTIC AIRMASSES INTO TEXAS. MODELS ARE FORECASTING THE SURFACE
HIGH BEHIND THE ASSOCIATED COLD FRONT TO ENTER THE CONUS NEAR
MONTANA SUNDAY. SURFACE HIGHS WHICH ENTER IN THIS REGION ARE KNOWN
TO BE FAVORABLE FOR THE COLDEST AIRMASSES FOR THE SOUTHERN PLAINS.
THIS IS MOSTLY DUE TO COLD AIR DAMMING WHICH OCCURS AS THE COLD
AIRMASS MOVES SOUTH ON THE LEE SIDE OF THE ROCKIES. AS THE HIGH
CIRCULATION DROPS SOUTH...EAST WINDS ON THE SOUTHERN PERIPHERY GET
BLOCKED BY THE TERRAIN AND THE COLD AIR IS ALLOWED TO POOL AND
COLLECT AS THE HIGH MOVES SOUTH. THIS ALLOWS THE AIR TO BECOME MORE
DENSE WHICH EQUATES TO COLDER AIR. IT WILL BE INTERESTING TO SEE HOW
THIS SYSTEM PLAYS OUT...BUT MODELS TEND TO BE TOO WARM WITH
TEMPERATURES WITH THIS PATTERN BY THE TIME THE COLD AIR MAKES IT
INTO TEXAS. ANOTHER INTERESTING PIECE TO THIS PUZZLE IS MODELS ARE
IN FAIRLY GOOD AGREEMENT THAT A PIECE OF THE TROUGH WILL MOVE
THROUGH THE AREA SOMETIME NEXT WEEK AFTER THE COLD AIR MAKES IT.
THERE ARE TIMING AND STRENGTH DISCREPANCIES BETWEEN THE MEDIUM-RANGE
GUIDANCE AND THIS IS LIKELY TO BE THE CASE FOR THE NEXT SEVERAL
DAYS. HOWEVER...MODELS THEN DO AGREE ON ENOUGH MOISTURE FOR PRECIP
WITH THE SYSTEM. THE QUESTION THEN TURNS TO HOW TO CONVEY THE
POSSIBILITY OF WINTER PRECIP IN THE OFFICIAL FORECAST FOR DAY 7. FOR
NOW...WILL MENTION A RAIN OR FREEZING RAIN MIX FOR THE HILL COUNTRY
TUESDAY NIGHT. THIS IS A GOOD START BECAUSE THERE ARE SOME TIMING
AND STRENGTH DIFFERENCES WITH THE TROUGH AS IT MOVES THROUGH THE
REGION. THERE IS THE POTENTIAL THAT THE AIR MASS WILL COLDER THAN
WHAT THE GFS IS SUGGESTING...SIMILAR TO THE ECMWF SOLUTION FOR
TEMPS. THIS BEARS WATCHING AS THE FORECAST IS LIKELY TO CHANGE ONE
WAY OR THE OTHER AS THE NEXT WEEK PROGRESSES.

[South Texas Storms]

Yeah he writes great AFDs Porta. Merry Christmas everyone! I'm optimistic that a large part of Texas will see some type of wintry precipitation in the next month. I hope it's snow for all of us!

[PauleinHouston]

Merry Christmas and Happy Holidays to all on this board. Learned a ton so far and continue to do so every time I login!

From the astute Mr. Jeff Linder at 3:56 p.m. today:

Arctic Outbreak

Increasing potential for strong arctic intrusion next week with possible winter storm 12/31-1/2.

Cold advection continues today with NW winds and temperatures in the 50’s which will set the stage for a cold and clear night and mostly sunny and cool Christmas with lows in the 30’s and highs in the 60’s.

Rapid changes underway on Friday as moisture returns ahead of the next incoming Pacific system. Clouds will increase and moisture may be enough by afternoon to support a few showers. Next cold front crosses the area Saturday night with showers and thunderstorms likely and then a period of post frontal upglide and rain Saturday night into at least the first part of Sunday with cold conditions. Overall the upcoming weekend will cool to cold and wet.

Next week:
Much of the focus continues to be on the middle to end of next week as very cold air looks increasingly likely to head southward. Strong upper level jet stream amplification will begin late this week with deep layer ridging pushing deep into Alaska and as far as 60 degrees north with the formation of a formidable downstream trough over the western and central US. Models are coming into decent agreement on this pattern and a very cold air mass dislodging from NW Canada and dropping southward under a large 1050mb+ arctic high pressure cell into Montana. This is an extremely favorable pattern to deliver very cold air to TX as the air mass dams against the Rockies mountains and surges quickly southward. Model guidance is almost certainly under-estimating the amount of cold air and likely is too slow in its arrival. Looks like the arctic front will enter TX next Tuesday and roar southward and off the coast next Wednesday…could be slightly faster than that with some models showing a 1045-1050mb high dropping as far south as Colorado out of WY and 1035-1040mb pressures into NW TX. Temperatures will tumble behind the frontal passage with strong cold air advection. Will need to undercut guidance, but not sure how much at this point given potential clouds and linger post frontal precipitation. Not looking at anything record breaking, but possible for a period of sub freezing temperatures even for daytime highs during the latter part of next week and the first weekend of 2015.

Forecast models continue to suggest a portion of the positive tilted trough hangs back over the SW US allowing period of moisture to upglide over the arctic dome and produce periods of precipitation. Model soundings are showing mainly rain and freezing rain profiles for SE TX around New Year’s Eve and Day….but given how poorly they handle such air masses they are likely too warm and too far NW with their freezing rain. Depending on the amount of moisture it looks like temperatures will be cold enough to support P-type concerns across a good portion of TX and SE TX and this is something that will have to be watched closely over the next few days as details begin to firm up on what sort of storm system we may be facing ejecting across in the cold air mass. Overall setup looks favorable for a winter storm across TX New Year’s Eve and Day.

[ronyan]

Interesting discussion by Hampshire there. 3 SD's above normal ridge, this means only about .3% of the time would you expect to see a ridge with higher anomalies in that region.

[northjaxpro]

Excellent analysis by Jeff Linder. I think he is pretty spot on about the looming arctic air outbreak and potential winter storm over Texas heading into the New Year's Day period next week.

[ronyan]

:uarrow: Excellent analysis by Jeff Linder. I think he is pretty spot on about the looming arctic air outbreak and potential winter storm over Texas heading into the New Year's Day period next week.

Indeed, I think he makes a good decision to undercut the guidance in this forecast.

[SouthernMet]

latest PGFS has 6-8" for a large portion of central & north texas... a bit more reasonable than the 2 feet it showed yesterday.. might finally be on to something. GFS keeps everything significant west of I-35.

[SouthernMet]

From FWD...

MODEL GUIDANCE IS IN GOOD AGREEMENT WITH BRINGING A CHUNK OF
ARCTIC AIR SOUTHWARD EARLY NEXT WEEK. A 1050MB SURFACE HIGH BUILDS
INTO MONTANA BY LATE MONDAY WITH THE ARCTIC FRONT SPILLING
SOUTHWARD INTO NORTH TEXAS ON TUESDAY. TEMPERATURES WILL BE
SHARPLY COLDER WITH BRISK NORTH WINDS. THIS SYSTEM BEARS CLOSE
WATCHING AS IT COULD BE FAVORABLE FOR WINTRY PRECIPITATION ACROSS
NORTH TEXAS. WITH A STRONG UPPER TROUGH STILL TO THE WEST THROUGH
MID WEEK AND THE 850MB TROUGH AXIS CLOSE BY...THERE COULD BE GOOD
WARM MOIST ADVECTION INTO NORTH TEXAS ATOP A VERY COLD AIRMASS.
THIS IS USUALLY FAVORABLE FOR FREEZING RAIN. RIGHT NOW IT LOOKS
LIKE A DEEPER COLDER AIRMASS WILL MAKE IT THROUGH THE AREA. WITH
COLDER TEMPERATURES ALOFT...SOME SORT OF MIX OR TRANSITION TO
SLEET THEN SNOW APPEARS MORE LIKELY. WITH A DEEPER COLDER AIRMASS
IN PLACE...MOISTURE QUALITY BECOMES MORE OF AN ISSUE AS WELL. WILL
CONTINUE TO MONITOR THIS SYSTEM CLOSELY THROUGH THE WEEKEND AS IT
COULD MAKE A MESS OF THE NEW YEAR HOLIDAY.

[KatDaddy]

Merry Christmas everyone!!!!!!

A RATHER COOL AFTERNOON WITH MAX TEMPS STRUGGLING TO WARM INTO THE
UPPER 50S. CLOUD COVER OVER THE EASTERN HALF OF THE AREA WILL EXIT
THE REGION BY SUNSET LEAVING CLEAR SKIES OVERNIGHT. WINDS WILL
ALSO DECOUPLE AS SFC HIGH PRESSURE OVER NORTHERN MEXICO DRIFTS
EAST. THE HIGH WILL BE EAST OF THE REGION ON THURSDAY AND WINDS
WILL BECOME ONSHORE AND STRENGTHEN AS LOW PRESSURE OVER SE
COLORADO DEEPENS. MOISTURE LEVELS WILL DEEPEN ON FRIDAY AS ONSHORE
WINDS PERSIST. PW VALUES ON FRIDAY REACH 1.10 AND FCST SOUNDINGS
SATURATE TO AROUND 800 MB. MOISTURE LOOKS DEEP ENOUGH TO GENERATE
A FEW SHOWERS BY FRI AFTN. PW VALUES REACH 1.40 INCHES ON SATURDAY
AHEAD OF ANOTHER COLD FRONT. THE FRONT WILL TRIGGER SCATTERED
SHOWERS AND THUNDERSTORMS AS IT CROSSES THE AREA. POST FRONTAL
RAIN WILL LIKELY PERSIST SAT NITE INTO EARLY SUNDAY AS THE FLOW
ALOFT REMAINS OUT OF THE SOUTHWEST AND SFC WINDS WILL BE NORTH.
ISENTROPIC UPGLIDE SHOULD BE MAXIMIZED SAT NIGHT. A S/WV TROUGH
WILL APPROACH THE PACIFIC COAST ON SATURDAY NIGHT AND THIS
FEATURE WILL NUDGE ANOTHER S/WV OVER SW TX EASTWARD. THE TEXAS
S/WV FILLS AS IT MOVES EAST AND THE FLOW ALOFT BECOMES ZONAL BY
MON 00Z. THE SET UP FOR ISENTROPIC UPGLIDE ON SUNDAY WHICH LOOKED
EXTREMELY FAVORABLE 24 HOURS AGO LOOKS CONSIDERABLY LESS FAVORABLE
NOW. THE CANADIAN CONTINUES TO SHOW SOME POTENTIAL FOR ISENTROPIC
UPGLIDE WHILE THE GFS AND ECMWF HAVE BACKED OFF. GLOBAL MODELS
CONTINUE TO SHOW SE TX IN A POTENT 155 KT RRQ WHICH SHOULD ENHANCE
PRECIP THROUGH EARLY SUN AFTN. SUBSIDENCE IN THE WAKE OF THE
DEPARTING S/WV SHOULD ALLOW FOR A BRIEF PERIOD OF DRY WEATHER AND
CLEARING SKIES ON MONDAY. ANOTHER UPPER TROUGH WILL DEVELOP OVER
THE SW U.S. AND ISENTROPIC UPGLIDE DEVELOPS AGAIN ON TUESDAY WITH
CLOUDS AND LIGHT RAIN RETURNING. THE ECMWF IS BRINGING VERY COLD
AIR INTO TEXAS AROUND THE NEW YEARS HOLIDAY AND FCST SOUNDINGS DO
SHOW SOME POTENTIAL FOR SLEET/FRZ RAIN NORTH OF A BRYAN TO
LIVINGSTON LINE.

[wxman57]

Yeah! Send me lots of lumps of coal! I'll use them to stoke the Earth's furnace and warm things up across Texas!

Merry Christmas, everyone!

[Ntxw]

A little off topic on the coming arctic blast, but the models are hinting at (finally) a full split of the stratospheric vortex;the true polar vortex. If this indeed occurs we would see a true mid winter major sudden stratospheric warming event. It's not a strong signal yet but just something to think about heading into January.

[TeamPlayersBlue]

Uggghhhh these models are taking FOREVER.

[Tireman4]

Yeah! Send me lots of lumps of coal! I'll use them to stoke the Earth's furnace and warm things up across Texas!

Merry Christmas, everyone!

Ha ha ha. No. You had 2011...we have 2014-2015... Merry Christmas Young Heat Miser

[Portastorm]

The 0z GFS has a 1051mb high in western Nebraska at lunchtime Tuesday. If the source region of this air is really from the Arctic, then these progged temps in the 0z run are way too warm for Texas. The model does break out precip in south Texas late on Tuesday.

[TeamPlayersBlue]

The 0z GFS has a 1051mb high in western Nebraska at lunchtime Tuesday. If the source region of this air is really from the Arctic, then these progged temps in the 0z run are way too warm for Texas. The model does break out precip in south Texas late on Tuesday.

Agreed. Has the temps somewhere in the 60's lol. Looks like its still on track for the old air. The precip does show up too in the form of a coastal low.

[ronyan]

The GFS surface looks out to lunch for SE TX, it bottles up the coldest anomalies in the TX Panhandle. Ho hum, just a weak January front...except for the 1050+ mb high behind it.

The Parallel run looks more reasonable but may still be too warm, it has a massive high in Montana on Tuesday (+132), 1058mb.

[SouthernMet]

Hmm, gfs & pgfs both keep dfw above freezing for the duration of the event. Neither has any accumulations.

[Big O]

The GFS surface looks out to lunch for SE TX, it bottles up the coldest anomalies in the TX Panhandle. Ho hum, just a weak January front...except for the 1050+ mb high behind it.

The Parallel run looks more reasonable but may still be too warm, it has a massive high in Montana on Tuesday (+132), 1058mb.

0z GFS Parallel has 3" of snow for Laredo, extending northeastward, with 2" of snow for San Antonio, and about 1" of snow for parts of Austin.