Texas Fall 2013

[paulb]

So just reading the forecasts on the National Weather Service website and reading the opinions and unofficial forecasts... North and West of DFW looks to be in a pretty good spot for seeing wintry precipitation the next few days? To what degree should I expect in Bridgeport?

[Jarodm12]

Ntxw, im in Waco visiting where do we sit in your opinion?

Waco is on the edge most likely if you were to believe the NAM and extent Euro. I wouldn't be surprised if sleet fell there but just to your west and NW would probably see some hefty accumulating sleet and/or snow.

There will be very heavy precip falling with perhaps thunderstorms involved overrunning the cold dome which is something I'm not familiar with and may play some kind of role.

Now if i'm not mistaken waco is in a bulls eye zone of heavy winter precip according to the 12z 18z nam and gfs. thunderstorms however if at all possible scenario, wouldn't the cloud top cool from the top down? not only because of cloud heights but also because of wet bulb effect? since there is a drying out period surely dew points will be below freezing? Very interested to see the 00z guidance truth be told they are all wrong. frontal placement and cold air depth are completely misrepresented. i'm starting to get excited.

[newtotex]

I'm traveling right now so not able to look at the maps. What's it looking like for Denton right now?

[Ntxw]

Now if i'm not mistaken waco is in a bulls eye zone of heavy winter precip according to the 12z 18z nam and gfs. thunderstorms however if at all possible scenario, wouldn't the cloud top cool from the top down? not only because of cloud heights but also because of wet bulb effect? since there is a drying out period surely dew points will be below freezing? Very interested to see the 00z guidance truth be told they are all wrong. frontal placement and cold air depth are completely misrepresented. i'm starting to get excited.

Wet bulbing is more about cooling near the surface. You can bring colder air down the column if the surface were above freezing with the wet-bulb, more likely to happen underneath the upper level low. It's the opposite case we may be seeing where the rain could bring warmer air aloft down, but I don't know if that's how it's going to work here. We're looking at different periods, one is before the passing of the upper low and this is where thunderstorms ahead of the low will come up and out of Mexico/Rio Grande valley over the cold and that's the sleet/ice pellets scenario first warm moist air over cold. The second opportunity is with the passage of the upper low and that's when we see the sleet/snow mix possibility with colder air aloft.

[dhweather]

Worth noting - NOAA has us with a warmer than normal winter.

http://www.noaanews.noaa.gov/stories201 ... tlook.html

[Ntxw]

Looking beyond this weekends system, I'm starting to notice the teleconnection indices coming together for a potential very very cold December setup. As Ntxw pointed out yesterday, the coldest air in the Northern Hemisphere is over North America right now and is forecast to build over the next few weeks. With the AO potentially going in the tank to start December, all of that cold air could be forced even further south into the US and could overwhelm the pattern. Just something to pay attention to going into next month.

I wouldn't be too worried about the AO. Big Aleutian ridging is progged to form last few days of November. As I've discussed with Portastorm for several months the waters to the south of the Gulf of Alaska are heating up. It's going to progress the ridging into the EPO region further. Expect more behemoth high(s) and arctic plunges forced by the Pacific Ocean in December. It's an attack on the mid continent of something that has plagued us for several years the other way

.

Our current arctic plunge began when the big Aleutian ridging that was near record breaking a few weeks ago (teamplayersblue posted) and I mentioned it was after the first cold blast that things would get interesting. It connected eastward with the high pressure dome off the west coast.

Nov 7th

While a cold air mass is poised to come down (thanks to NPAC ridging) I think the bulk will be aimed towards the east and Texas is side glanced, Aleutian ridging doesn't aim for Texas. What is more interesting is what happens after. The ridging in the Aleutians will be replaced by a deep trough thus shifting the ridge to Alaska and into NW North America. This is when we will see the EPO tank and the AO finally go negative and the pipeline to the Arctic opens heading closer to Thanksgiving.

And questions on why there is so much ridging in the NPAC. This has been going on all year. In the spring we had a cold March and April and July saw a freak chill, all connected to anomalous warm temps in the Gulf of Alaska and this is still going on.

[Jarodm12]

look at the 00z nam slowing the low

[TeamPlayersBlue]

Looking beyond this weekends system, I'm starting to notice the teleconnection indices coming together for a potential very very cold December setup. As Ntxw pointed out yesterday, the coldest air in the Northern Hemisphere is over North America right now and is forecast to build over the next few weeks. With the AO potentially going in the tank to start December, all of that cold air could be forced even further south into the US and could overwhelm the pattern. Just something to pay attention to going into next month.

I wouldn't be too worried about the AO. Big Aleutian ridging is progged to form last few days of November. As I've discussed with Portastorm for several months the waters to the south of the Gulf of Alaska are heating up. It's going to progress the ridging into the EPO region further. Expect more behemoth high(s) and arctic plunges forced by the Pacific Ocean in December. It's an attack on the mid continent of something that has plagued us for several years the other way

[img]http://i39.tinypic.com/k4jhj7.pn g[/img].

Our current arctic plunge began when the big Aleutian ridging that was near record breaking a few weeks ago (teamplayersblue posted) and I mentioned it was after the first cold blast that things would get interesting. It connected eastward with the high pressure dome off the west coast.

Nov 7th

While a cold air mass is poised to come down (thanks to NPAC ridging) I think the bulk will be aimed towards the east and Texas is side glanced, Aleutian ridging doesn't aim for Texas. What is more interesting is what happens after. The ridging in the Aleutians will be replaced by a deep trough thus shifting the ridge to Alaska and into NW North America. This is when we will see the EPO tank and the AO finally go negative and the pipeline to the Arctic opens heading closer to Thanksgiving.

And questions on why there is so much ridging in the NPAC. This has been going on all year. In the spring we had a cold March and April and July saw a freak chill, all connected to anomalous warm temps in the Gulf of Alaska and this is still going on.

That huge ridge could have pulled alot of that warm water up towards Gulf of Alaska too. December will be interesting. Cant wait

[Jarodm12]

00z nam colder slower low. waco sits at 5inch snow. likey sleet. this culd get very very interesting

[Ntxw]

Sleet on the nam

[Ntxw]

Here is the GFS precipitation type same time as nam, sleet

[vbhoutex]

vb picks himself up off the floor after hearing a local OCM say we may have a WINTRY MIX of precipitation in Houston and SE TX on Sunday! I will believe it when I see it.

[Tireman4]

Tim Heller. Vb? Lol

[weatherdude1108]

We got 1.43 inches of rain in about 30 minutes! There were at least 10 really close lightning strikes. Our dog was not pleased. I, the weather buff, was also getting scared. Very electrical storm! Lightning got worse after rain had stopped. Had to wait for the atmosphere to calm down before dog and I went outside. Crazy evening! Feel humbled.

I just saw front should arrive in Austin/SA area between 2 and 4am. Sooner than earlier predicted. Not stopping for anyone.

[somethingfunny]

I remember this fantastic AFD by Mr. Cavanaugh last Sunday. What happened to the mitigating factors he mentioned regarding this front?

Afternoon discussion from Cavanaugh...another great read!

THE CONCLUSION OF THIS DISCUSSION WILL BE SPENT EXPLAINING SOME OF
THE DIFFERENCES IN THE MODELS...THE POTENTIAL FOR VARIOUS OUTCOMES
DURING THE PERIOD...AND THE REASONS WHY. THERE IS NOT REALLY MUCH
ADDED TO THE DISCUSSION OF THE OFFICIAL FORECAST BELOW AS NO
SIGNIFICANT CHANGES WERE MADE. TEMPERATURES REMAIN BELOW NORMAL
THROUGH THE PERIOD AND ALL PRECIPITATION REMAINS LIQUID FOR NOW IN
THE OFFICIAL FORECAST...WHICH EXTENDS FROM TONIGHT THROUGH SUNDAY.

THE FIRST MAIN FORECAST CONCERN IS THE TIMING OF A COLD FRONT
THROUGH THE AREA SOMETIME FROM LATE ON THURSDAY THROUGH FRIDAY
EVENING. IN GENERAL THE ECMWF CONTINUES TO REPRESENT THE FASTEST
SOLUTION WITH REGARDS TO THE TIMING OF THE COLD FRONT AND BRINGS
IT INTO NORTH TEXAS THURSDAY EVENING. THE LATEST RUN 17/12Z IS A
BIT SLOWER THAN THE 00Z RUN...BUT STILL REMAINS FASTER THAN OTHER
OPERATIONAL GUIDANCE. THE 17/12Z GFS AND CANADIAN SOLUTIONS ARE
FASTER WITH THE FRONT THAN THEIR 00Z COUNTERPARTS...BUT STILL
REMAIN 18 TO 24 HRS SLOWER THAN THE ECMWF. TO HELP DETERMINE WHICH
SOLUTION IS MORE LIKELY TO VERIFY...IT CAN BE USEFUL TO LOOK AT
SOME FACTORS THAT TYPICALLY PLAY A BIG ROLE IN HOW FAST A CANADIAN
AIRMASS MOVES SOUTH ACROSS THE PLAINS.

A CANADIAN AIRMASS WILL MOVE THROUGH THE PLAINS FASTER THAN
EXPECTED IF...

1. THERE IS A FAIRLY CONTINUOUS SNOW PACK IN PLACE ACROSS THE
NORTHERN AND CENTRAL PLAINS.

2. WESTERLY FLOW ALOFT OVER THE ROCKIES IS WEAK. (THE FLOW ITSELF
DOES NOT NEED TO BE WEAK...JUST THE WESTERLY DIRECTION/COMPONENT
OF THE WIND.)

3. THE UPPER TROUGH DRIVING THE CANADIAN AIRMASS INTO THE REGION
DIGS FAR ENOUGH SOUTH TO SEND STRONG PRESSURE RISES/A POWERFUL
ANTICYCLONE SOUTH THROUGH THE PLAINS. (I.E. NOT EAST ACROSS THE
PLAINS).

FROM WHAT WE CAN SEE IN THE MASS FIELDS OF THE MODELS...THAT IS
IGNORING SIMPLE MODEL OUTPUT LIKE PRECIPITATION TYPE AND
QPF...SHEDS SOME LIGHT ON WHICH SOLUTION IS LIKELY TO VERIFY AT
THE END OF THE WEEK.

UNLESS SOMETHING SIGNIFICANT CHANGES THIS WEEK... A CURRENT LOOK
AT THE NORTHERN AND CENTRAL PLAINS INDICATES NO SNOW PACK.

THE INITIAL UPPER TROUGH THAT SENDS THE LATE WEEK COLD FRONT SOUTH
THROUGH THE PLAINS MOVES OVER THE NORTHERN PLAINS AND THEN OFF
OVER EASTERN CANADA BY FRIDAY. THIS INDICATES THAT POINT NUMBER 3
IS GOING TO BE A PROBLEM...SO AT LEAST EARLY ON...THE ANTICYCLONE
ASSOCIATED WITH THIS TROUGH IS UNLIKELY TO SURGE SOUTH THROUGH
FRIDAY.

LASTLY...AS THE FRONT MOVES SOUTH LATE THIS WEEK...THE STRONG
SOUTHERN STREAM UPPER TROUGH MOVES ON SHORE THE SOUTHERN
CALIFORNIA COAST. THIS TROUGH WILL SPREAD STRONG WESTERLY WINDS
OVER THE SOUTHERN CONUS ROCKIES RESULTING IN PRESSURE FALLS /NOT
RISES/ OVER THE HIGH PLAINS. THIS GENERALLY WORKS TO SLOW DOWN
COLD FRONTS NOT SPEED THEM UP. AS A RESULT...CONTINUED TO SIDE
WITH THE GFS/CANADIAN TIMING TO THE LATE WEEK FRONT...BRINGING IT
SOUTH ACROSS NORTH TEXAS DURING THE DAY ON FRIDAY.

THE AIRMASS BEHIND THE FRONT IS LIKELY TO BE MODIFIED QUITE A BIT
ON ITS SOUTHWARD PUSH FRIDAY...SO TEMPERATURES ARE EXPECTED TO
REMAIN WELL ABOVE FREEZING THROUGH THE END OF THE WEEK. SHOWERS
AND THUNDERSTORMS WILL LIKELY ACCOMPANY THE FRONT...SO WENT AHEAD
WITH 40 TO 50 POPS ACROSS THE AREA AS A RESULT.

THIS WEEKEND...NEARLY ALL GUIDANCE INDICATES THAT THE SOUTHERN
CALIFORNIA TROUGH WILL BECOME CUT OFF FROM THE JET STREAM AND
REMAIN QUASI-STATIONARY THROUGH THE WEEKEND. AT THE SAME TIME
GUIDANCE INDICATES THAT ANOTHER...POSSIBLY STRONGER NORTHERN
STREAM TROUGH WILL DIG SOUTH ACROSS THE EASTERN CONUS BY SATURDAY
NIGHT SENDING ANOTHER SURGE OF CANADIAN AIR SOUTH THROUGH THE
PLAINS.

THE GENERAL DYNAMICS OF THIS SECOND PUSH OF CANADIAN AIR ARE MORE
FAVORABLE FOR QUICK PASSAGE INTO NORTH TEXAS AND REPRESENT A MUCH
BETTER THREAT FOR BRINGING TEMPERATURES DOWN TOWARDS IF NOT
SLIGHTLY BELOW FREEZING SOMETIME FROM LATE SUNDAY THROUGH MONDAY
MORNING.

THIS IS BEYOND THE CURRENT SCOPE OF THE FORECAST...BUT WITH THE
UPPER LOW HOLDING OFF TO OUR WEST...THERE IS AT LEAST SOME CHANCE
THAT LIFT WILL SPREAD OVER THIS COLD AIRMASS RESULTING IN
PRECIPITATION AT NEAR-FREEZING TEMPERATURES LATE SUNDAY THROUGH
MONDAY. THIS PERIOD REPRESENTS OUR BEST CHANCE AT GETTING SOME
FROZEN PRECIPITATION IN THE NEXT 10 DAYS AND WILL BE WATCHED
CLOSELY IN LATER FORECASTS AS A RESULT. ITS STILL ON THE LOWER END
OF WHAT IS LIKELY TO HAPPEN...BUT THIS LATE WEEKEND SURGE OF
CANADIAN AIR LOOKS STRONGER THAN WHAT WILL FILTER IN BEHIND OUR
FRONT ON FRIDAY.

CAVANAUGH

and... I wonder if this is sticking:

[SouthernMet]

FTW NWS issues WSW

[SouthernMet]

Just want to reiterate.. This isn't your typical "West Texas, Snow Storm". This setup has the potential to be a I-35 Corridor "Ice Storm" with most of the Heavier Precip falling as Sleet/Freezing Rain. (Which is actually more dangerous to travel/power) The key on Sunday is going to be exactly how cold, & how fast the freezing line moves through the DFW area. Because Models have now consistently trended wetter, with high QPF numbers at or below freezing. Also wanted to say, good job on those who picked up on the fact that GFS usually underestimates the speed/strength of these kind of cold fronts , we have seen this time after time.

[wxman57]

:cold: vb picks himself up off the floor after hearing a local OCM say we may have a WINTRY MIX of precipitation in Houston and SE TX on Sunday! I will believe it when I see it.

All models still indicate the freezing level up above 10,000 feet here through the weekend. If the models are REALLY off then there could be the chance of a stray sleet pellet, but they'd have to be quite a bit off.

[Ntxw]

Euro and NAM are locked in. This is going to be a significant/major sleet/snow storm for North Texas. If it pans out as progged it will be one of our biggest winter storms and definitely for November.




****

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE FORT WORTH TX
352 AM CST FRI NOV 22 2013

TXZ093>095-102>107-117>120-130>133-141>144-156-157-221800-
/O.NEW.KFWD.WS.A.0001.131124T1200Z-131125T1800Z/
GRAYSON-FANNIN-LAMAR-WISE-DENTON-COLLIN-HUNT-DELTA-HOPKINS-PARKER-
TARRANT-DALLAS-ROCKWALL-ERATH-HOOD-SOMERVELL-JOHNSON-COMANCHE-
MILLS-HAMILTON-BOSQUE-LAMPASAS-CORYELL-
INCLUDING THE CITIES OF...SHERMAN...DENISON...BONHAM...PARIS...
DECATUR...BRIDGEPORT...DENTON...LEWISVILLE...FLOWER MOUND...
THE COLONY...PLANO...GREENVILLE...COMMERCE...COOPER...
SULPHUR SPRINGS...WEATHERFORD...BRIAR...FORT WORTH...ARLINGTON...
DALLAS...ROCKWALL...STEPHENVILLE...DUBLIN...GRANBURY...
OAK TRAIL SHORES...GLEN ROSE...CLEBURNE...BURLESON...COMANCHE...
DE LEON...GOLDTHWAITE...HAMILTON...HICO...CLIFTON...MERIDIAN...
VALLEY MILLS...LAMPASAS...COPPERAS COVE...GATESVILLE
352 AM CST FRI NOV 22 2013

...WINTER STORM WATCH IN EFFECT FROM SUNDAY MORNING THROUGH
MONDAY MORNING...

THE NATIONAL WEATHER SERVICE IN FORT WORTH HAS ISSUED A WINTER
STORM WATCH...WHICH IS IN EFFECT FROM SUNDAY MORNING THROUGH
MONDAY MORNING.

* TIMING...SUNDAY MORNING THROUGH MIDDAY MONDAY.

* MAIN IMPACT... SLEET AND ICE ACCUMULATIONS ON SUNDAY INTO MONDAY
MAY SEVERELY IMPACT TRAVEL ON ALL AREA ROADS AND BRIDGES AND
DISRUPT AIR TRAVEL INTO MONDAY.

* OTHER IMPACTS...ANY ICE ACCUMULATIONS MAY CAUSE POWER OUTAGES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.

&&

$$

DUNN

[horselattitudesfarm]

Well, I don't know enough about all the models to predict whats what, but I can tell you this.........I didn't get didley-squat for rain last night with the front. I was very disappointed that such cold air couldn't squeeze more rain out of that soupy warm airmass that was over us yesterday.