January Weather Discussion: Slight Chance Severe Storms

[TexasMetBlake]

Wow, this run is WAY warmer than 12z. All the cold air goes east this time with a much weaker high. The pattern is looking very La Nina. Unfortunately, the 00z Euro is far warmer and weaker with the high than 12z. The upper-levels are very unfavorable for cold air to reach us. Perhaps it's just a junk run. Let's not get too bent out of shape, yet.

[Badfish]

Wow, this run is WAY warmer than 12z.

I guess a little more "realistic" than the freezemegeddon that was the 12z. I was going to go corner the PVC market tomorrow, oh well, back to the drawing board.

[TexasMetBlake]

I suspect that there will be more flip flops to come. The 00z Euro is still cold, but nothing record breaking for our area. The Euro flipped flopped today a bit so I'm not too worried at this time. Not to mention, the GFS is still showing bitterly cold conditions here.

[TexasMetBlake]

At 240, it shows the -10 isotherm reaching to almost Pensacola, FL. So the cold air is there this run, but not for us. Appears as though it all goes east.

[Andrew]

At 240, it shows the -10 isotherm reaching to almost Pensacola, FL. So the cold air is there this run, but not for us. Appears as though it all goes east.

Also it is still pretty cold for us. The 0 isotherm is all the way down to Corpus. We would probably get in the mid 20's on that run. Now it is not as strong as the last run but it is still pretty strong. Especially if that cold air went straight south and not to the east. The GFS still showed a straight south pattern and has been for a while. So I will wait until the 12z runs before thinking things are changing.

[TexasMetBlake]

Well with an airmass this significant, I guess what I mean by 'cold' is the teens and single digits that would have occured at the 12z run of the Euro. This run 'only' shows mid 20s for us with highs probably in the upper 30s to low 40s....a far cry from the 'below freezing for days' talk.

[Andrew]

Well with an airmass this significant, I guess what I mean by 'cold' is the teens and single digits that would have occured at the 12z run of the Euro. This run 'only' shows mid 20s for us with highs probably in the upper 30s to low 40s....a far cry from the 'below freezing for days' talk.

I'm sure the euro and gfs is going to go back and forth a couple times.

[TexasMetBlake]

The last time something like this happened:

http://www.youtube.com/watch?v=RsRMi43u ... ature=fvwp

[TexasMetBlake]

Norman, OK: Nothing to exciting...


FOCUS
THEN SHIFTS TO AN ARCTIC COLD FRONT THAT WILL BRING A BITTERLY COLD
AIRMASS TO THE REGION. MODELS CONT TO DIFFER AS TO THE TIMING OF
THIS FRONT BUT NOW APPEARS THAT IT WILL ARRIVE AND MOVE ACROSS
THE FA SOMETIME LATE SUN/SUNDAY NIGHT. HOWEVER... MODELS CONT TO
CHANGE THIS TIMING SO WHEN THIS FRONT WILL ACTUALLY ARRIVE IS STILL
UP FOR GRABS. THE ECMWF SEEMS A BIT FASTER THAN THE GFS WHICH WILL
AFFECT THE TEMPERATURE FORECAST FOR MONDAY. THE UPPER SYSTEM THAT
DRIVES THIS COLD FRONT ACROSS THE REGION WILL ALSO MAINTAIN THE
CHANCE FOR PRECIP ACROSS PARTS OF THE FA LATE THIS WEEKEND INTO
EARLY NEXT WEEK. THIS SECOND SYSTEM WILL BRING A CHANCE FOR WINTRY
PRECIPITATION TO PARTS OF THE FA BEFORE ENDING EARLY NEXT WEEK. ONCE
THIS COLD AIRMASS MOVES INTO THE REGION... MODELS SHOW THAT IT WILL
REMAIN STUBBORN AFFECTING THE AREA THROUGH MUCH OF NEXT WEEK WITH
HIGHS POSSIBLY ONLY CLIMBING INTO THE 20S FOR SEVERAL DAYS IN SOME
LOCATIONS.

[ticka1]

Its time to sit back and just wait - will the models swing back to us having the coldest weather we seen since 1989 or will it begin to shift and modify with us just getting a glance of it or not even be recordbreaking - with it going East!!!

friday and over the weekend will be a better idea of getting a accurate handle on it...

[Baseballdude2915]

6z GFS looks way warmer. Hopefully the 12z will bring back the Freezmageddon.

[Andrew]

6z GFS looks way warmer. Hopefully the 12z will bring back the Freezmageddon.

The 6z surface analysis of the GFS was not the best run. With a 1064mb high with almost due south counter lines should push the cold air much further south than being depicted. The 500mb vort still shows a pretty decent setup comparable to the 12z run. It's still looking good on the gfs. Let's see what the 12z run has to offer.

[srainhoutx]

Dallas/Ft Worth has a excellent discussion and explains well the differences via the models and the hints of what the ensemble members are showing which forecasters must consider for continuity at this range...

MAIN WEATHER STORY IS THE COLDER WEATHER EXPECTED INTO THE REGION
NEXT WEEK. THERE REMAINS EXCELLENT AGREEMENT AMONG THE MODELS THAT
A PATTERN CHANGE WILL OCCUR AS BLOCKING UPPER HIGHS/LOWS DEVELOP
AND PERSIST ACROSS THE NORTHERN LATITUDES. A COLD AIR MASS WILL
BEGIN TO DEVELOP AND ORGANIZE ACROSS WESTERN CANADA THIS WEEKEND
WITH SURFACE TEMPS THERE BEGINNING TO FALL BELOW 0 AS A LARGE
SPRAWLING SURFACE HIGH GATHERS INTENSITY. THIS CANADIAN AIR MASS
IS POISED TO MOVE SOUTH AND ARRIVE INTO NORTH TEXAS BEGINNING
MONDAY. SINCE THE UPPER PATTERN STAYS BLOCKED...THE GATES TO THE
NORTH WILL REMAIN OPEN AND COLD AIR WILL CONTINUE TO POUR SOUTH
INTO THE CENTRAL US FOR SEVERAL DAYS. THUS IT IS WITH HIGH
CERTAINTY THAT WE CAN SAY AN EXTENDED PERIOD OF COLDER THAN
NORMAL WEATHER WILL OCCUR IN NORTH TEXAS NEXT WEEK.

AS FAR AS HOW COLD...AND WHETHER THIS EVENT WILL BE ONE OF THOSE
MEMORABLE DECADE EVENTS...IS ANOTHER QUESTION. AT LEAST THROUGH
FRIDAY JAN 14TH...ODDS ARE THAT THIS COLD SPELL WILL NOT BE
ANYWHERE NEAR RECORD TERRITORY AND LOOKS COMPARABLE TO THE ONE
LAST YEAR IN EARLY JANUARY. LAST NIGHT I WROTE ABOUT THE BENEFITS
OF ANALYSIS OF THE SOURCE REGION OF THESE COLD AIR MASSES...
PARTICULARLY AT THE 500MB-700MB LEVEL. I DUG UP THE UPPER AIR DATA
FROM A DOZEN OF OUR BIGGEST COLD SNAPS SINCE 1970. THESE HISTORIC
ARCTIC OUTBREAKS UNANIMOUSLY CONTAINED 500-700MB TEMPS 5 TO 10 DEG
C COLDER THAN WHAT ANY MODEL IS FORECASTING OVER CANADA THIS
WEEKEND. IN ADDITION 850MB TEMPS ACROSS THE NORTHERN US ARE
FORECAST TO BE ABOUT 5 DEG C WARMER EARLY NEXT WEEK THAN WHAT OUR
SIGNIFICANT OUTBREAKS HAD. THUS WE CAN MAKE FORECAST TEMPERATURE
EXTRAPOLATIONS BASED OFF A MODEL/S UPPER AIR FORECASTS 5 DAYS OUT
RATHER THAN RELYING ON A MODEL/S SURFACE TEMP FORECAST 10 DAYS OUT
WHICH IS OBVIOUSLY PRONE TO MORE ERRORS.

SO FOR THE SPECIFICS...MONDAY/S HIGHS SHOULD LIKELY BE IN THE 40S
AS FROPA OCCURS THAT MORNING. LOWS MONDAY NIGHT SHOULD BE IN THE
20S AREA WIDE WITH BREEZY NORTH WINDS CONTINUING. HIGHS TUESDAY
THROUGH FRIDAY LOOK TO STAY IN THE 30S AREA WIDE DESPITE GENERALLY
SUNNY SKIES. WINDS SHOULD SUBSIDE MORE BY MID LATE WEEK WITH LOWS
LIKELY IN THE TEENS TO LOW 20S EACH NIGHT.

BEYOND JAN 14TH...IT IS TOUGH TO SAY EXACTLY WHAT WILL HAPPEN.
YESTERDAY/S MODEL RUNS WERE MORE BULLISH THAT NEXT WEEK/S COLD
SPELL WAS JUST THE START OF SOMETHING MORE SERIOUS. THE LATEST
GFS/ECMWF/GEM OPERATIONAL RUNS AND ENSEMBLE MEANS AT 240 HOURS ARE
DEPICTING AN UPPER LEVEL PATTERN NOT EXACTLY FAVORABLE FOR A
HISTORIC OUTBREAK. THEY HAVE ALL TRENDED THE BLOCKING HIGH OVER
ALASKA EITHER TOO FAR NORTH OR TOO FAR WEST INTO SIBERIA. THIS
MEANS THE POSITIVELY TILTED UPPER TROUGH AXIS OVER THE SW US /A
CRUCIAL COMPONENT TO GET AN ARCTIC OUTBREAK HERE...AND A KEY TO
MEETING THE REQUIREMENTS OF THE SO-CALLED MCFARLAND PATTERN
SIGNATURE/ BECOMES IN QUESTION...SINCE A POSITIVE TILT TROUGH OR
KINK OFTEN NATURALLY DEVELOPS SOUTHEAST OF AN UPPER HIGH. WITHOUT
THIS TROUGH THE REAL ARCTIC AIR JUST HAS A TOUGH TIME MAKING IT
THIS FAR SOUTH. HOWEVER...ABOUT 1/3 OF THE ENSEMBLE MEMBERS KEEP
THIS SW TROUGH IN TACT...AND THEY SHOW A VERY COLD/INTENSE POLAR
LOW DEVELOPING OVER CANADA AND THE US IN 10 DAYS. LOTS OF
UNCERTAINTY AND MODELS WILL CONTINUE TO CHANGE DAILY. BUT THE
REASON WHY WE ARE WATCHING THIS SO CLOSELY IS BECAUSE A 30 PERCENT
CHANCE OF OCCURRENCE IS PRETTY HIGH FOR AN EVENT WHICH WOULD HAVE
ENORMOUS AND WIDESPREAD ECONOMIC IMPLICATIONS FOR OUR REGION...AS
WE LEARNED IN THE DEEP FREEZES OF 83 AND 89.
TR.92

Dodge City as well...

DAYS 3-7...

THE EXTENDED PERIOD IS THURSDAY THROUGH NEXT TUESDAY. MADE SOME
MINOR CHANGES FOR THURSDAY AND FRIDAY WITH TEMPERATURES. I WARMED
TEMPERATURES UP A BIT BY BLENDING THE PREVIOUS FORECAST WITH THE 00Z
ECMWF. DRY UPPER LEVEL NORTHWEST FLOW WITH 500 HPA SHORTWAVE RIDGING
IN RESPONSE TO AN APPROACHING UPPER LEVEL TROF ACROSS THE DESERT
SOUTHWEST WILL ALLOW TEMPERATURES TO CLIMB ABOVE NORMAL TOWARDS THE
END OF THE BUSINESS WEEK. BY SATURDAY, THIS LOW WILL BE CLOSE
ENOUGH TO BRING IN POPS TO THE SOUTHEAST CWFA. A WARM AIR ADVECTION
PATTERN AHEAD OF THIS UPPER LEVEL TROUGH SHOULD ALLOW FOR RAIN AS
850 HPA TEMPERATURES WARM UP TO AROUND 7 DEG ACROSS SOUTHERN KANSAS
AND INTO OKLAHOMA BY SATURDAY AFTERNOON. THE UPPER TROF WILL
TRAVERSE EAST ACROSS TEXAS WHILE ANOTHER UPPER LEVEL TROF HEADS
ACROSS THE ROCKIES WITH A SURFACE REFLECTION IN THE FORM OF AN
ARCTIC COLD FRONT. HAVE LARGELY FOLLOWED ECMWF TIMING FOR BOTH OF THESE
FEATURES. THE ATMOSPHERIC COLUMN SHOULD BE COULD ENOUGH FOR SNOW BY
SUNDAY MORNING AS THE ARCTIC COLD FRONT TRAVERSES ACROSS KANSAS BY
SUNDAY NIGHT. AGAIN, BLENDED THE PREVIOUS FORECAST TO THE 00Z ECMWF.
THE 00Z ECMWF IS A LITTLE WEAKER THAN COMPARED TO THE 12Z ECMWF AS
FAR AS SURFACE PRESSURE RISES ARE CONCERNED BUT THE SAME SYNOPTIC
PATTERN CONTINUES. SO AS IT STANDS RIGHT NOW, THE INTRODUCTION TO
THE ARCTIC AIR WILL HAPPEN SOMETIME BETWEEN SUNDAY NIGHT AND MONDAY
MORNING. TEMPERATURES MONDAY WILL BE MUCH COOLER...GENERALLY IN THE
LOW TO MID 20S FOLLOWED BY SINGLE DIGIT LOWS TUESDAY MORNING. THE
COLD WEATHER WILL COME IN MULTIPLE SURGES OF ARCTIC AIR WITH THE
COLDEST TEMPERATURES EXPECTED BY THE MIDDLE OF NEXT WEEK AS A
1045-1050 HPA SURFACE HIGH SLIDES OVER THE GREAT PLAINS. WITH THE
VERY STRONG 500 HPA HIGH DOMINATING OVER ALASKA AND A CONTINUED LONG
FETCH OF NORTH TO SOUTH ARCTIC AIR, I DO NOT SEE TEMPERATURES
MODERATING THAT MUCH AND THINK THAT THE ARCTIC AIR WILL REMAIN
ENTRENCHED OVER THE PLAINS ALL NEXT WEEK WITH TEMPERATURES FOR THE
DODGE CITY CWFA REMAINING IN THE SINGLE DIGITS FOR LOWS (WITH A GOOD
CHANCE OF NEGATIVE TEMPERATURES TO THE NORTH) AND TEENS FOR HIGHS
WELL INTO THE END OF NEXT WEEK. -SUGDEN

[srainhoutx]

The only issue I would bring up regarding those ensembles, Ed, is one will need to see the spread of the individual members and base a sensible forecast on what those members show. With 30% suggesting a cold pattern, one has to consider that those are rather high odds in the longer range of that cold air coming S versus E. Frankly, I would have been surprised had we not seen a bit of change via guidance. As I explained yesterday to CC in a conversation, remember how the models handle the EC Christmas storm and the OTS (out to sea) fiasco? Expect show run to run changes and look for continuity as we get closer to the weekend. Also of note we should be able to see the air mass late this week into the weekend via surface obs in AK and Western Canada.

[srainhoutx]

I also would suggest reading San Angelo. Forecaster Johnson provides some great detailed analysis of what many having beeing seeing in the pattern ahead. Notice how McFarland continues to be mentioned...

LONG TERM...
THE CUT OFF UPPER LOW OFF THE CA COAST WILL FINALLY EJECT OUT TO THE
EAST BY LATE THIS WEEK. IN THE MEANTIME...WE CAN EXPECT SHORTWAVE
RIDGE AXIS EXTENDING UP THE SPINE OF THE SIERRA MADRE WITH
NORTHWESTERLY FLOW ALOFT ACROSS THE CENTRAL CONUS. THIS WILL BRING
SEVERAL WEAK WAVES ACROSS THE SOUTHERN PLAINS THAT WILL KEEP THE
SURFACE FLOW PREDOMINANTLY FROM THE WEST/NORTHWEST FOLLOWING WEAK
FRONTAL PASSAGES. THE FIRST OF THESE WILL MOVE THROUGH THE AREA
EARLY WEDNESDAY. THIS WILL TEMPER THE WARM UP...KEEPING HIGHS NEAR
60 ACROSS THE BIG COUNTRY BUT THIS FRONT SHOULD NOT HAVE MUCH PUSH.
THUS...THE SOUTHERN 2/3 OF THE AREA WILL BE IN THE MID/UPPER 60S.
SLIGHTLY COOLER TEMPS ARE ANTICIPATED THURSDAY. TEMPS IN THE H85-H7
LAYER WILL BE A FEW DEGREES COOLER AND INCREASING MID/HIGH CLOUD
WILL LIMIT THE MIXING POTENTIAL. WINDS SHOULD BE LIGHT AS THE
SURFACE ANTICYCLONE SETTLES OVER THE REGION. SOUTHWEST SURFACE WINDS
WILL RETURN ON FRIDAY AS PRESSURE FALLS COMMENCE IN THE LEE OF THE
ROCKIES. TEMPS SHOULD WARM INTO THE MID/UPPER 60S ACROSS THE ENTIRE
CWA WITH NIL RAIN CHANCES THROUGH THIS TIME. THERE IS SOME CONCERN
THAT THE UPPER LOW COULD EVEN BE SLIGHTLY SLOWER THAN IS CURRENTLY
PROGGED GIVEN THE PSEUDO REX BLOCK CONFIGURATION.

LOW LEVEL MOISTURE WILL ALSO BE ON THE INCREASE AS WE HEAD INTO THE
WEEKEND. ISENTROPIC ASCENT WILL INCREASE LATE FRIDAY NIGHT WHICH
SHOULD RESULT IN WIDESPREAD STRATUS BY SATURDAY MORNING ACROSS MUCH
OF THE AREA. AS THE DAY PROGRESSES...STRONG LARGE SCALE LIFT WILL
OVERSPREAD THE AREA AS THE UPPER LOW APPROACHES. POPS IN THIS
PACKAGE WILL RANGE FROM 20 PERCENT IN THE WEST TO 40 PERCENT IN THE
EAST WHERE THE DEEPEST MOISTURE WILL BE FOUND. THERE WILL BE SOME
ELEVATED CONVECTIVE INSTABILITY DURING THE DAY SO A FEW RUMBLES OF
THUNDER CANNOT BE RULED OUT BY I HAVE LEFT THE PRECIP TYPE AS
SHOWERS FOR NOW. THE LOW CLOUDS FOR MUCH OF THE DAY WILL KEEP THE
DIURNAL RANGE LOW AND ANY STORMS THAT COULD DEVELOP WOULD BE
ELEVATED AND FEW AND FAR BETWEEN. THE UPPER LOW IS PROGGED TO CROSS
THE CWA SATURDAY NIGHT WITH LARGE SCALE SUBSIDENCE TAKING OVER AS WE
HEAD INTO SUNDAY. THUS...POPS WERE REMOVED FOR THE LATTER HALF OF
THE WEEKEND WITH TEMPS A FEW DEGREES WARMER THAN THOSE ON SATURDAY.

THE MAJORITY OF MY ATTENTION IS FOCUSED ON THE POTENTIAL FOR A
SUBSTANTIAL COLD FRONT FOR NEXT WEEK. AN ARCTIC COLD FRONT IS POISED
TO ARRIVE SUNDAY NIGHT BRINGING MUCH COLDER TEMPERATURES TO WEST
CENTRAL TX. THE SYNOPTIC PATTERN BY THE WEEKEND RESEMBLES THAT OF
PATTERNS PRECEDING OTHER SIGNIFICANT COLD SNAPS ACROSS THE THE STATE
OF TX /MCFARLAND/. THE RIDGE OVER THE STATE OF AK WILL PROVIDE A
CROSS POLAR COMPONENT TO THE FLOW WHICH WILL TAP INTO VERY COLD
SIBERIAN AIR. THIS WILL RENDER MOS TEMPS ESSENTIALLY USELESS FOR THE
LAST FEW DAYS OF THE PACKAGE. HIGH TEMPS ON MONDAY WILL RELY HEAVILY
ON THE ACTUAL TIMING OF THE FRONT AND THE PRESENCE OF ANY LOW CLOUD
COVER. I CURRENTLY HAVE HIGHS IN THE 40S FOR MUCH OF THE CWA AND
THAT COULD BE RATHER GENEROUS IF THE FRONT ARRIVES BY 12Z. BY
TUESDAY...HIGH TEMPS ARE EXPECTED TO BE IN THE MID 30S IN MOST
AREAS. LOW TEMPERATURES ACCOMPANYING THIS AIRMASS WILL BE IN THE
TEENS AND LOWER 20S. THIS COULD BE A PROLONGED COLD SNAP AS THE
MODELS KEEP H85 TEMPS BELOW FREEZING THROUGH PRETTY MUCH THE ENTIRE
WEEK. AT THIS TIME...IT APPEARS THAT IF ANY PRECIPITATION WERE TO
ACCOMPANY THIS FRONT IT WOULD BE ACROSS THE EXTREME EAST/SOUTH
SUNDAY NIGHT BUT AS FAST AS THIS FRONT SHOULD BE MOVING ANY PRECIP
WOULD NOT LAST LONG. OF COURSE...WE ARE STILL LOOKING OUT BEYOND DAY
5 AND THE FORECAST COULD UNDERGO SUBSTANTIAL MODIFICATION.
HOWEVER...THE MODELS HAVE BEEN FAIRLY CONSISTENT WITH THIS SCENARIO
FOR SEVERAL DAYS SO CONFIDENCE IS INCREASING WITH EACH RUN.

JOHNSON

[tireman4]

I wonder if HGX is hedging their bets on this one..wanting to make darn sure this is right before committing....

[ticka1]

I wonder if HGX is hedging their bets on this one..wanting to make darn sure this is right before committing....

Watch and wait mode perhaps. Two or three more days of model runs should fine tune the event for the models.

[srainhoutx]

Don't forget that HGX does have their hands full with the pattern this week as well. The longer range focus will come and soon, I suspect.

[brazoria121]

So is this just based on one bad run or do we expect more flip flops till say sat/sun for sure when the models have this things pinned down for sure

[srainhoutx]

I really don't see the over night runs as 'bad'. The synoptic pattern suggests otherwise. Forecasters will not swing one way or the other based on individual model runs. It is that synoptic pattern that should be focused on at this range.