Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 5

[bubba hotep]

72 when I got home around 8:30 and now down to 41, not too shabby.  Some crazy plumes going on in the 21z SREFs

[Ed Lizard]

GFS is a shade too warm for DFW excitement, NAM is almost too cold, that melted snow will completely refreeze.  Cold and rain sucks, snow is pretty, freezing rain is an adventure.  But if it is sleet for Dallas, in November, I'll be ok.

 

I'd even endure miserable 40sF temps in Houston to let it happen.  Ballpark 2 inches of rain at my house per HGX 88D, that partially offsets a miserably cold weekend as well. 

[Ed Lizard]

Just looking at NAM, Austin is less than 1ºC from the mother of ice storms.  And unlike Dallas, if we can cool it down that 1ºC, it would be subcooled rain, not sleet, and the trees and powerlines would mean no classes Monday at The University of Texas.
 

[NJ_Ken]

It goes without saying that 60 hours is pretty far beyond the NAM's wheelhouse (and even inside of 48 hours the NAM is no prize pig), but these soundings are still VERY interesting.   A decent swath of Texas is definitely going to get socked with an ice storm for the ages.... the only question now is exactly who that is going to be.  If I were a betting man (and luckily I am not), I think Dallas gets a repeat of the Thanksgiving 93 storm and gets an inch or two of sleet while somebody between Austin and Dallas (Waco... I am looking at you!) is going to need an ice pick to open their front door come Monday morning, assuming, of course, a tree or utility pole hasn't crashed down on their house first.     

[DFWWeather]

Current temp at DFW Airport is 35°F (dewpoint 32°F) with sleet falling. Interesting!

[bubba hotep]

It has been waffling b/w 34 & 35 here since about noon.  Collin County reporting:

 

Location Time(cst) Sky/Weather Temp.(ºF) Dewpt.(ºF) Humidity(%) Wind(mph) Pressure
(in) Collin County Regional Airport 13:53 Freezing Rain Fog/Mist 36 34 93 N 14 G 23 30.38

[DFWWeather]

It has been waffling b/w 34 & 35 here since about noon.  Collin County reporting:

 

Location Time(cst) Sky/Weather Temp.(ºF) Dewpt.(ºF) Humidity(%) Wind(mph) Pressure

(in) Collin County Regional Airport 13:53 Freezing Rain Fog/Mist 36 34 93 N 14 G 23 30.38

 

Wouldn't it by definition be impossible to get freezing rain with a surface temp above 32°F. Sure that sleet is what is coming down? If sleet come down hard enough, it will drag the temperature down. The process of how sleet forms cools the surface temp.

[bubba hotep]

Wouldn't it by definition be impossible to get freezing rain with a surface temp above 32°F. Sure that sleet is what is coming down? If sleet come down hard enough, it will drag the temperature down. The process of how sleet forms cools the surface temp.

That is what I was thinking    Maybe sleet?

[Ed Lizard]

32ºF at Alliance (Texas Motor Speedway).

 

It occasional mixes a sleet pellet down here (Houston) even near 40ºF, usually evaporative cooling involved when it happens here.

 

Re- freezing rain and slighly above freezing, if raining hard enough, subcooled rain drops falling through a very thin layer of barely above freezing air may remain subcooled, I'd think, and if the temp has been well below freezing and is just starting to climb above freezing, I'd think some objects might also freeze.

 

But I haven't really thought deeply about it.

[Ed Lizard]

Just looking at NAM, Austin is less than 1ºC from the mother of ice storms.  And unlike Dallas, if we can cool it down that 1ºC, it would be subcooled rain, not sleet, and the trees and powerlines would mean no classes Monday at The University of Texas.

 

Not quite there yet, but so close, and the trend is our friend.  GFS is a touch warmer and quite a bit less wet, crippling Austin ice storm is by no means a certainty yet,

[bubba hotep]

I like these trends   

 

NAM & GFS keep inching ever closer to laying down a nice layer of accumulating snow on top of the ice, IMBY.

 

ETA: Even the 00z Euro could do the trick

[Ed Lizard]

12Z GFS and NAM just not quite as fun as earlier runs, with heavier precip developing a bit too far East of I-35 on both models.

 

 

Not all bad, the heavier precip is near IMBY.

[bubba hotep]

A bit of a northward shift in the modeled QPF on the 18z GFS, wouldn’t take much more to really hammer IMBY.  FWD mentioned a 3^rd round of precipitation, most likely snow, moving through Tuesday morning in the afternoon discussion.

 

THE MAIN UPPER LOW WILL TRACK ACROSS THE LONE STAR STATE ON
TUESDAY...TAKING A FARTHER SOUTH TRAJECTORY THAN EARLIER
ANTICIPATED. THIS COULD RESULT IN YET ANOTHER ROUND OF WINTRY
PRECIPITATION TUESDAY MORNING. WITH LARGE-SCALE FORCING FURTHER
COOLING THE COLUMN...THE PRECIP MODE WILL LIKELY BE SNOW
THROUGHOUT THE CWA. HAVE KEPT ACCUMULATIONS LOW AT THIS POINT.
WITH AMOUNTS LIKELY WITHIN ADVISORY CRITERIA AT BEST...NO NEED TO
ADDRESS WITH A WATCH AT THIS TIME.

 

Now on to the most important GFS run of this winter, the 00z

 

ETA: GFS Trend for KDFW (total precip)

 

00z - 0.56"

06z - 0.97"

12z - 0.20"

18z - 0.55"

 

[DoctorMu]

Yep - Hearne/CLL will be at the end of the tongue of wintry mischief.  Could be a glaze on bridges or up to an inch of sleet.  Timing is everything.      

 

 

 

[Quixotic1]

DPs now in mid-20s.

Setting up nicely.

[Ed Lizard]

Long but worth the read

 

.PREV DISCUSSION... /ISSUED 522 AM CST SUN NOV 24 2013/

THE PRIMARY FOCUS FOR THIS FORECAST PACKAGE OVER THE NEXT 7 DAYS
REMAINS ON THE NEXT 48 HOURS WHEN A WINTER STORM IS EXPECTED TO
IMPACT MUCH OF NORTH AND CENTRAL TEXAS.

THE PRIMARY PLAYERS INVOLVED IN BRINGING THIS FORECAST FOR WINTRY
WEATHER OVER THE REGION WERE CONVERGING ON TEXAS THIS
MORNING. A COLD...ARCTIC AIRMASS WAS IN PLACE AND A LARGE UPPER
LOW CONTINUED TO MOVE EAST TOWARDS THE SOUTH PLAINS.  OVERALL THE
LARGE SCALE PATTERN CONTINUES TO LOOK FAVORABLE FOR A WIDESPREAD
SLEET OR FREEZING RAIN EVENT ACROSS NORTH AND CENTRAL TEXAS
BEGINNING TODAY AND NOT ENDING UNTIL MONDAY AFTERNOON. WHILE THE
LARGE SCALE PATTERN REMAINS FAVORABLE FOR THIS EVENT...THERE ARE
SEVERAL DETAILS THAT COULD MAKE A HUGE DIFFERENCE ON IMPACTS FOR
THE REGION. THE DETAILS AND CONTENTS OF THE OFFICIAL FORECAST ARE
DISCUSSED BELOW...FOLLOWED BY THOUGHTS ON ALTERNATE SCENARIOS THAT
COULD ARISE.

A WINTER STORM WARNING REMAINS IN EFFECT FOR ALMOST ALL OF NORTH
AND CENTRAL TEXAS FROM TODAY THROUGH NOON ON MONDAY. 10Z REGIONAL
RADARS SHOWED A NORTH/SOUTH BAND OF PRECIPITATION EXTENDING ALONG
A LINE FROM CHILDRESS TO SAN ANGELO...MOVING EAST TOWARDS NORTH
TEXAS. SURFACE OBSERVATIONS WERE REPORTING LIGHT SNOW AT CHILDRESS
AND LIGHT FREEZING RAIN FURTHER SOUTH. RADAR RETURNS WERE JUST
BEGINNING TO MOVE OVER THE WESTERN COUNTIES OF THE CWA AT THE TIME
OF THIS DISCUSSION...AND INITIALLY PRECIPITATION WAS NOT REACHING
THE GROUND OVER GRAHAM AND BRECKENRIDGE.

THE 00Z FWD AND OUN RAOBS INDICATED A SHALLOW LAYER OF EXTREMELY
DRY AIR LOCATED FROM 925 TO 800 MB. UNFORTUNATELY THERE WAS A
DEARTH OF AVAILABLE AIRCRAFT SOUNDINGS THIS MORNING AROUND THE DFW
METROPLEX. THE LAST AVAILABLE SOUNDING...FROM 0530Z...OBSERVED A
DEEP ISOTHERMAL LAYER OF PLUS 1 DEG C FROM THE SURFACE TO 700
MB...OR ABOUT 3 KM DEEP. ASSUMING THE 00Z FWD SOUNDING REMAINED
SOMEWHAT REPRESENTATIVE OF THE VERTICAL MOISTURE PROFILE OVER THE
REGION BY 05Z...THE SHALLOW LAYER OF DRY AIR WOULD LEAD TO A SUB-
FREEZING WET-BULB LAYER OF ABOUT 3000 FT THICK OVER NORTH TEXAS
THIS MORNING. WHILE IT WILL TAKE SOME TIME FOR PRECIPITATION TO
SATURATE THIS DRY LAYER...IT IS NOT EXPECTED TO BE DEEP ENOUGH TO
PREVENT PRECIPITATION FROM REACHING THE GROUND THROUGHOUT THE DAY
TODAY. WITH A NEARLY SOLID LINE OF PRECIPITATION MOVING OUR
WAY...THINK THAT WE WILL HAVE OUR SUB-FREEZING LAYER WET-BULBED
INTO PLACE FOR MOST LOCATIONS WEST OF INTERSTATE 35 BY 18Z.

10Z SURFACE TEMPERATURES WERE SLIGHTLY COOLER THAN EXPECTED ACROSS
MUCH OF NORTH AND CENTRAL TEXAS THIS MORNING...PRIMARILY DUE TO
BREAKS IN THE CLOUD COVER THAT LED TO EFFICIENT RADIATIONAL
COOLING OVERNIGHT. EVEN WITHOUT DRAGGING ANY RAIN COOLED AIR DOWN
TO THE SURFACE...THE WET-BULB ZERO LINE WAS LOCATED SOUTH OF
INTERSTATE 20 EARLY THIS MORNING. THIS ADDS CONFIDENCE TO THE
LIKELIHOOD OF TEMPERATURES RAPIDLY FALLING BELOW FREEZING WITH THE
ONSET OF ANY MEASURABLE PRECIPITATION. AS A RESULT THINK THAT
LIGHT PRECIPITATION MAY INITIALLY FALL AS RAIN...BUT WILL QUICKLY
TRANSITION OVER TO SLEET OR FREEZING RAIN AS OUR SHALLOW DRY LAYER
OF AIR ALOFT WET-BULBS OUT TO -5 DEG C OR THEREABOUTS.

MINUS 5 DEG C IS MORE OR LESS THE THRESHOLD WE LOOK AT FOR
DETERMINING WHETHER PRECIPITATION WILL BE ABLE TO FREEZE INTO
SLEET PELLETS OR FALL TO THE SURFACE AS SUPERCOOLED WATER/RAIN
DROPS. ITS NOT QUITE THAT CUT AND DRY OF COURSE...BUT ITS A DECENT
RULE OF THUMB WITHOUT KNOWING FOR SURE HOW DEEP AND COLD THE DRY
LAYER ALOFT WILL COOL DOWN TO THIS MORNING. AT ANY RATE...THINK
THAT LOCATIONS WEST OF INTERSTATE 35 COULD PICK UP TO A QUARTER OF
AN INCH OF SLEET...OR UP TO ONE TENTH OF AN INCH OF FREEZING RAIN
THIS MORNING/BEFORE 18Z AS ONGOING PRECIPITATION MOVES OVER THE
WESTERN HALF OF THE CWA.

LIGHT PRECIPITATION IS LIKELY TO CONTINUE TO MOVE EAST ACROSS
NORTH TEXAS THIS AFTERNOON...FOLLOWING A SIMILAR PATTERN OF A
TRANSITION FROM LIGHT RAIN TO SLEET OR FREEZING RAIN AS IT MOVES
EAST AND SATURATES THE ATMOSPHERE FROM THE TOP DOWN. PRECIPITATION
IS MORE LIKELY TO BE LOCATED NEAR THE INTERSTATE 35 CORRIDOR
AROUND NOON...PUSHING EAST THIS AFTERNOON. PRECIPITATION AMOUNTS
IN GENERAL ARE EXPECTED TO REMAIN LIGHT AS A SIGNIFICANT AMOUNT OF
PRECIPITATION WILL BE LOST EVAPORATING/WET-BULBING THE LOWER
ATMOSPHERE. PRECIPITATION TYPE IS A BIT MORE COMPLICATED EAST OF
INTERSTATE 35 THIS AFTERNOON AS THE LATE ONSET OF PRECIPITATION
MAY ALLOW SURFACE TEMPERATURES TO WARM UP INTO THE UPPER 30S
BEFORE PRECIPITATION STARTS. THIS WOULD LEAD TO MORE PRECIPITATION
FALLING AS A LIGHT RAIN/SLEET MIX WITH OVERALL A LESSER CHANCE OF
SEEING ANY FREEZING RAIN THROUGH 00Z. TO THE SOUTHEAST OF
CORSICANA...TEMPERATURES MAY ACTUALLY CLIMB INTO THE 40S ALLOWING
MOST PRECIPITATION TO FALL AS RAIN THROUGH 00Z TODAY. THIS IS
SOMETHING WE WILL JUST HAVE TO KEEP AN EYE ON THROUGHOUT THE DAY
TODAY AND UPDATE THE FORECAST AS NECESSARY.

THERE WILL LIKELY BE A BREAK IN THE PRECIPITATION FROM WEST TO
EAST FROM THIS AFTERNOON THROUGH THIS EVENING. THIS BREAK LOOKS
MOST LIKELY TO RESULT IN THE LOWEST COVERAGE OF ANY PRECIPITATION
ACROSS THE CWA FROM 00 TO 06Z MONDAY...OR THIS EVENING BEFORE
MIDNIGHT. THIS BREAK IN THE ACTION IS EXPECTED AS THE UPPER LOW
CURRENTLY OVER ARIZONA MOVES EAST SENDING ANOTHER ROUND OF STRONG
FORCING FOR ASCENT OVER THE REGION FROM SOUTHWEST TO NORTHEAST
TONIGHT. THE LEAD UPPER LEVEL DISTURBANCE BRINGING LIGHT
PRECIPITATION ACROSS THE CWA TODAY WILL ROTATE NORTH LEAVING US
UNDER A 6 HOUR WINDOW OF SUBSIDENCE BEFORE THE NEXT ROUND OF
FORCING ARRIVES.

AFTER MIDNIGHT...THE STRONGEST LARGE SCALE FORCING FOR ASCENT
ASSOCIATED WITH THE UPPER LOW IS EXPECTED TO SEND A MUCH HEAVIER
BAND OF PRECIPITATION OVER THE CWA. THE HEAVIEST PRECIPITATION IS
STILL EXPECTED TO FALL GENERALLY SOUTH OF THE DFW
METROPLEX...APPROXIMATELY ALONG A LINE FROM WAXAHACHIE TO
GOLDTHWAITE. HOWEVER ALMOST ALL OF NORTH AND CENTRAL TEXAS IS
EXPECTED TO RECEIVE PRECIPITATION BETWEEN MIDNIGHT AND 9 AM ON
MONDAY. FORECAST SOUNDINGS CONTINUE TO INDICATE A STRONG
LIKELIHOOD OF PRECIPITATION FALLING AS SLEET OR FREEZING RAIN
ALONG A LINE FROM SHERMAN TO DALLAS TO LAMPASAS DURING THIS TIME
FRAME. TO THE SOUTHEAST OF THIS LINE...PRECIPITATION IS SOMEWHAT
MORE LIKELY TO FALL AS FREEZING RAIN. TO THE NORTHWEST OF THIS
LINE PRECIPITATION IS MORE LIKELY TO FALL AS SLEET...AND POSSIBLY
TRANSITION OVER TO SNOW...ESPECIALLY NEAR GRAHAM AND BOWIE AND
AREAS NORTHWEST. THE WORST SLEET AND ICE ACCUMULATIONS ARE
EXPECTED DURING THIS PERIOD...AND THIS IS WHEN TRAVEL CONDITIONS
ARE MOST LIKELY TO BE AT THEIR WORST.

SLEET ACCUMULATIONS ARE GENERALLY EXPECTED TO BE ON THE ORDER OF 1
INCH DURING THIS EVENT...WITH FREEZING RAIN ACCUMULATIONS LIKELY
AROUND ONE QUARTER INCH TO THE SOUTHEAST OF THE LINE THAT WAS
MENTIONED ABOVE. ELSEWHERE...FREEZING RAIN ACCUMULATIONS ARE MORE
LIKELY TO BE LESS THAN ONE QUARTER OF AN INCH. FOR THOSE LOCATIONS
THAT TRANSITION OVER TO ALL SNOW LATE TONIGHT INTO MONDAY
MORNING...1 TO 2 INCHES OF SNOW ACCUMULATION ARE POSSIBLE.

PRECIPITATION IS EXPECTED TO TRANSITION FROM FROZEN FORM TO ALL
RAIN FROM SOUTHEAST TO NORTHWEST AFTER 15Z/9AM MONDAY. FOR
LOCATIONS SOUTHEAST OF CORSICANA...THERE MAY ONLY BE A BRIEF...6
HOUR WINDOW...WHERE PRECIPITATION WILL TRANSITION OVER TO A FROZEN
FORM. A SIGNIFICANT AMOUNT OF FORECAST PRECIPITATION TOTALS WILL
FALL AS ALL RAIN FOR FAR SOUTHEAST COUNTIES INCLUDED IN THE WINTER
STORM WARNING...WITH LOCATIONS NEAR A MARLIN TO PALESTINE LINE
JUST BARELY REACHING WARNING CRITERIA WITH SLEET OR FREEZING RAIN
ACCUMULATIONS BEFORE SUNRISE MONDAY. THE REMAINDER OF THE WATCH
AREA IS MUCH MORE LIKELY TO REACH WARNING CRITERIA OF OVER ONE
HALF INCH OF SLEET...OR ONE QUARTER INCH OF FREEZING RAIN DURING
THIS EVENT.

IN GENERAL THE CHANCES FOR A VERY HIGH IMPACT ICE STORM SEEM TO
HAVE DECREASED...HOWEVER SIGNIFICANT TRAVEL PROBLEMS ARE STILL
LIKELY IN THE WINTER STORM WARNING AREA AFTER MIDNIGHT TONIGHT
THROUGH MONDAY MORNING.

NOW I WILL BRIEFLY GO OVER SOME ALTERNATE SCENARIOS AND POINT OUT
SOME KEY THINGS TO LOOK FOR DURING THIS EVENT TO HAVE SOME IDEA IF
THE FORECAST IS GOING OFF TRACK.

IF YOU ARE A BIG USER OF RAW MODEL DATA...IT IS FAIRLY OBVIOUS
THAT FROM 12Z YESTERDAY TO 00Z...MODEL GUIDANCE WAS GENERALLY
WARMER WITH REGARDS TO SURFACE TEMPERATURES AND PRECIPITATION TYPE
OUTPUT. FOR INSTANCE THE SREF HAS PERSISTENTLY SHOWN RAW MODEL
OUTPUT OF ALL RAIN DURING THIS EVENT FOR DFW AIRPORT WITH A
SURFACE TEMPERATURE HOVERING AROUND 33 DEG F. MOST RAW MODEL
OUTPUT WAS SHOWING SOME VARIATION OF THIS GENERAL SOLUTION. IT IS
DIFFICULT TO IMAGINE RAW MODEL OUTPUT MORE DIFFICULT TO INTERPRET
THAN THIS. TAKEN AT FACE VALUE...THERE WILL BE NO WINTER WEATHER
EVENT AT DFW.  THE ONE INCH OR SO OF FORECAST PRECIPITATION WILL
FALL AS ALL RAIN AS THE TEMPERATURE HOLDS RIGHT AT 33 DEG F. WHILE
THIS IS TECHNICALLY POSSIBLE...THIS SEEMS LIKE A VERY UNLIKELY
OUTCOME...FOR WHICH REASONS ARE PROVIDED BELOW:

WHILE THE SREF HOVERS A SURFACE TEMPERATURE JUST ABOVE
FREEZING...THE DEW POINT IS EXPECTED TO REMAIN BELOW FREEZING...IN
FACT THE DEW POINT MEAN IS FORECAST TO HOLD BELOW 30 DEGREES UNTIL
SUNRISE ON MONDAY. ANYTIME WE RECEIVE ANYTHING MORE THAN A
SPRINKLE OF PRECIPITATION...NEAR SURFACE RELATIVE HUMIDITY VALUES
SHOULD INCREASE CLOSE TO 100 PERCENT...MEANING SOMETHING HAS TO
GIVE. THE DEW POINT HAS TO INCREASE QUICKLY OR THE TEMPERATURE HAS
TO DROP. CONSIDERING ONGOING LIGHT PRECIPITATION TO OUR WEST HAS
BEEN CAUSING TEMPERATURES TO COOL BY 3-4 DEGREES CONSISTENTLY...
IT SEEMS FAIR TO ASSUME TEMPERATURES HAVE A GOOD CHANCE AT FALLING
BELOW 33 DEGREES WHILE PRECIPITATION IS FALLING.

THE SREF AND MOST OTHER OPERATIONAL MODELS INCREASE TEMPERATURES
QUICKLY ACROSS THE REGION DURING THE DAY ON MONDAY. QUITE A BIT OF
TIME WAS SPENT LOOKING FOR A REASON FOR THIS. THE MOST LIKELY
REASON MODELS ARE DOING THIS APPEARS TO BE BECAUSE MODELS ARE
INCORPORATING SOME DIURNAL INCREASE IN TEMPERATURE DUE TO SOLAR
INSOLATION...THAT IS HEATING FROM THE SUN. THIS IS A GREAT REASON
TO INCREASE SURFACE TEMPERATURES ON MOST DAYS...HOWEVER ALL
GUIDANCE INDICATES THICK CLOUD COVER OVER THE REGION UNTIL A BIG
MID-LEVEL DRY SLOT PUNCHES OVER THE WESTERN CWA BEGINNING MONDAY
AFTERNOON. WITH THICK CLOUDS IN PLACE...ONGOING PRECIPITATION AND
NO STRONG LOW-LEVEL WARM AIR ADVECTION TO SPEAK OF...THERE IS NO
LOGICAL REASON FOR SURFACE TEMPERATURES TO INCREASE 3-5 DEGREES
FROM SUNRISE TO NOON ON MONDAY. FORECAST SOUNDINGS EVEN INDICATE
THAT PRECIPITATION FALLS THROUGH A 3000 FT DEEP LAYER OF SUB
FREEZING AIR BEFORE REACHING THE SURFACE...SO IT IS NOT LIKE WARM
RAIN SHOULD BRING TEMPERATURES UP QUICKLY.  AS A RESULT...MODELS
ARE LIKELY BEING OVERLY FAST IN FORECASTING A CHANGE OVER TO ALL
RAIN FROM SOUTHEAST TO NORTHWEST ON MONDAY. THIS CHANGE OVER TO
RAIN IS LAGGED IN THE OFFICIAL FORECAST AS A RESULT.

ALL THAT SAID...IT IS DISTURBING THAT THERE IS A LOT OF MODEL
CONSENSUS FORECASTING SURFACE TEMPERATURES ABOVE FREEZING IN RAW
MODEL OUTPUT. IT IS CERTAINLY POSSIBLE THE MODELS ARE PICKING UP
ON SOMETHING THAT IS NOT OBVIOUS FROM A THOROUGH ENVIRONMENTAL
ANALYSIS. IF THAT ENDS UP BEING THE CASE AND RAW MODEL OUTPUT IS
RIGHT ON DESPITE RESERVATIONS MENTIONED ABOVE...MOST OF THE WINTER
STORM WARNING EAST OF INTERSTATE 35 AND SOUTH OF INTERSTATE 20
WOULD BE UNNECESSARY. FOR REASONS MENTIONED ABOVE...ICY
ACCUMULATIONS ARE STILL EXPECTED FOR THESE LOCATIONS AND TRAVEL
IMPACTS ARE EXPECTED TO CONTINUE TO WARRANT A WARNING AT THIS
TIME. ALSO...ITS NOT LIKE THERE IS NO MODEL GUIDANCE TO SUPPORT
THIS FORECAST...ECMWF AND GFS MOS GUIDANCE SEEM TO OFFER UP A MUCH
MORE REALISTIC PORTRAYAL OF WHAT IS LIKELY TO TRANSPIRE WITH
REGARDS TO TEMPERATURES AND PRECIPITATION TYPES DURING THIS WINTER
WEATHER EVENT.

THE ONLY OTHER ALTERNATE SCENARIO CONTINUES TO BE OFFERED UP BY
THE CANADIAN. THIS MODEL CONTINUES TO BE SIGNIFICANTLY COOLER AND
WETTER THAN ALL OTHER GUIDANCE. IT IS NOT EXPECTED TO VERIFY AS IT
REALLY HAS NO OTHER SUPPORT...ASIDE FROM MAYBE 1 OR 2 ENSEMBLE
MEMBERS FROM THE 23/21Z SREF. IF THIS MODEL WERE TO VERIFY FOR
...A MUCH HIGHER IMPACT ICE STORM WOULD OCCUR OVER THE REGION. AT
THIS TIME THERE IS MUCH LESS SUPPORT FOR THIS SOLUTION THAN THE
MOSTLY LIQUID RAIN SOLUTION DESCRIBED ABOVE...SO I WONT GO INTO
ANY MORE DETAIL HERE AS IT PROBABLY WILL NOT PAN OUT.

FOR THIS FORECAST...USED A PRECIPITATION TIMING BASED CLOSELY ON
THE CONUS 4 KM HIGH RESOLUTION NAM OUTPUT FROM 00Z. THE 06Z GFS
SEEMED TO BE DOING A MUCH BETTER JOB WITH TEMPERATURES IN
PRECIPITATION...AND WAS GENERALLY PREFERRED ALONG WITH MOS
GUIDANCE FROM THE ECMWF AND GFS.

THERE IS STILL A SMALL CHANCE FOR SOME SNOWFALL OVER THE REGION
BEHIND THE UPPER LOW MONDAY NIGHT INTO TUESDAY MORNING. AT THIS
TIME JUST HAVE LOW POPS IN THE FORECAST AS MOST GUIDANCE INDICATES
THE UPPER LOW DIGS TOO FAR SOUTH TO RESULT IN A SIGNIFICANT TROWAL
OVER NORTH TX AT THIS TIME. THIS IS SOMETHING WE WILL HAVE TO
REVISIT IN LATER FORECASTS AS TROWAL STRUCTURES ARE NOTORIOUS FOR
PRODUCING SMALL AREAS OF HIGH SNOWFALL AMOUNTS DUE TO THEIR
DYNAMICS COMMONLY SUPPORTING BANDED SNOWFALL.

CAVANAUGH
 

 

 

[bubba hotep]

That was a good read but I don’t share his “enthusiasm” for the forecast verifying.  I’m getting a feeling that was very familiar when I lived in the DC area… bust city.  I agree with what he is saying and it makes sense meteorologically speaking but betting against the models seems to payoff less and less these days.

[Quixotic1]

That was a good read but I don’t share his “enthusiasm” for the forecast verifying. I’m getting a feeling that was very familiar when I lived in the DC area… bust city. I agree with what he is saying and it makes sense meteorologically speaking but betting against the models seems to payoff less and less these days.

I tend to agree with you since the returns dont seem heavy enough to moisten up such a dry column.

[Quixotic1]

Sleet and freezing rain here in frisco.

[bubba hotep]

34 here with a bit of sleet mixing in with the rain

[DoctorMu]

There's tiny sleet mixed in with the rain in CLL about 1:30 pm

 

The DP was 28°F and hoping the column cools - looks like all rain now.

[Quixotic1]

returns look poor off to the west. getting a bit pessimistic

[bubba hotep]

18z GFS trying to rally for the DFW area! 

Nearly doubles QPF at KDFW to almost 0.50",

there is a really tight gradient and even a

slight NW jog gets a lot of the area E of I35

into something interesting.  FWD still

betting on evaporative cooling overnight to help us out. 

IMBY, sitting at 33 with some meager returns approaching from the SW.  

[bubba hotep]

I am kind of liking the radar returns starting to pop out in W Texas.

 

ETA:

Perusing some of the models and it doesn’t look like any really had that area popping just yet.  Maybe forcing is coming stronger or faster or more north than modeled? Grasping at straws at this point to get that area of heavier precip shifted NW into DFW    

[bubba hotep]

That warm nose has been hard to shake...

 

[bubba hotep]

FWD finally throwing in the towel and pulling down the warnings

[bubba hotep]

We ended up around 0.75” of rain, IMBY, but the temp hovered right around freezing the whole time.  So close to something interesting but ended up with just some ice in the tress. The GFS has been hinting that the timeframe around Dec 4 – 7^th could be interesting.

[Quixotic1]

We ended up around 0.75” of rain, IMBY, but the temp hovered right around freezing the whole time.  So close to something interesting but ended up with just some ice in the tress. The GFS has been hinting that the timeframe around Dec 4 – 7^th could be interesting.

Yeah, my trees look like sculptures, but melting now.  If that scenario had played out say four weeks from now, I doubt that warm layer would have been there. 

[DFWWeather]

The GFS and ECMWF and their ensembles are hinting at major Arctic air (serious cross polar flow) invading the lower 48 around or after December 6th through 10th.

[Srain]

Getting rumbles of thunder now while setting at 42F in SE Texas. Dynamic storm system continues to develop in the NW Gulf of Mexico as a cold core upper low is nearing Central Texas.