Texas winter wx thread#4 - big changes on the way eventually

[Air Force Met]

Looking at the 12Z and 18Z runs of the GFS(see EWG's post above), I might get some moderate snow tomorrow. Maybe even enough to get an accumulation on grassy surfaces. Of course, this is all contingent on the models being right, but I am encouraged by the last 2 model runs. The trend is my friend.

Where are you located?

BTW...I'm class of '92. Here's hoping we have a Holiday Bowl Victory next week!

[aggiecutter]

I'm located in Texarkana, which is in the extreme NE part of the state.

[KatDaddy]

EWG you are always over the top but this time I agree with you. It just may happen again for someone in SE TX.

[Air Force Met]

I'm located in Texarkana, which is in the extreme NE part of the state.

Never heard of it...

Just joking...been through there many times on I-30.

Your local office isn't giving you any chance of snow...which is why I think it funny the HGX office talking snow. If points N and E can't get snow closer to the low and more into the cold air...how are we?

Well...it is weather and flukes do happen. But...I bet there was some talk in the offfice and some "Hey...watch this guys...I'm putting a chance of snow in the forecast...hehehehe."

[Extremeweatherguy]

I'm located in Texarkana, which is in the extreme NE part of the state.

Never heard of it...

Just joking...been through there many times on I-30.

Your local office isn't giving you any chance of snow...which is why I think it funny the HGX office talking snow. If points N and E can't get snow closer to the low and more into the cold air...how are we?

Well...it is weather and flukes do happen. But...I bet there was some talk in the offfice and some "Hey...watch this guys...I'm putting a chance of snow in the forecast...hehehehe."

Shreveport is mentioning snow in their AFD:

VERTICAL TEMPERATURE PROFILE TAKING
THE SHAPE OF A WEST TO EAST GRADIENT. EXPECT ANY CHANGEOVER FORM
RAIN TO SNOW TO OCCUR JUST WEST OF FA. TEMPERATURE AND DEPTH OF CLOUD
LAYER OVER SE OK/NE TX PLENTY SUFFICIENT FOR SNOW GENERATION...BUT
FREEZING LEVELS SHOULD REMAIN ABOUT 4000 FEET SO MAY DODGE THE
BULLET AS FAR AS ANY ANY WINTER PCPN. WILL MENTION POSSIBILITY OF
A BRIEF CHANGOVER TO SNOW FLURRIES NEAR SE OK. IF THIS DOES
HAPPEN...SLIGHT CHANGE IN CAA COULD RESULT IN FLURRIES AS FAR
SOUTH AS EAST TX LAKES.

Seems like they think the best chance is to their west, but they do mention possible snow reaching well into their forecast area if the situation plays out right.

[Ptarmigan]

I heard on the local news that there may be a snow flurry or two later tonight to early Christmas morning.

[Portastorm]

What's the latest news from Mt. Bastardi, Portastorm?

Nothing new from what I shared the other day. More of the same for us with some possible arctic air by the middle of January. Still waiting on Wise One to share his weekly wisdom for our "zone."

[Air Force Met]

Seems like they think the best chance is to their west, but they do mention possible snow reaching well into their forecast area if the situation plays out right.

They aren't too confident...they only mention it for extreme SE OK and Extreme NE TX...not even including Texarkana...and they mention the 4000' freezing level...and there is only a 30% chance...

So...there is not a great chance we will have ANY precip.

I think a lot of local mets are forgetting the basic forecasting rules for snow...or maybe it is that they haven't spent a lot of time forecasting for snow...hence the "problems." There could always be a fluke flurry...and the freezing level could be lower than expected...but not likely.

Just to show people where I am coming from...I am going to give the rules of thumb one uses for forecasting snow. Now...NOt the 850 temp or the thickness...because forecasting for snow is much more complicated than that. When I give these rules...remember that the WBZ is forecasted to about 3000' and the freezing level should be about 4000'...and the models are only putting down .01-.03" of rain...so forget evap cooling. Also remember the max temp of the warm layer is expect to be..at minimum...4C.

Here are the rules.

1) If the temp of the warm layer is >3C...expect complete melting of the snow...regardless of how close the freezing level is...unless it is very close to the sfc and the WBZ is at the sfc (basically no WBZ level). If the temp is 1C to 3C...expect partial melting. If temp is <1C...no melting should occur.

2)
Freezing level / Probability Precip Falls as snow
300' / 90%
600' / 70%
950' / 50%
1200' / 30%
1500' / 10%
2000' / 0%

Those are the rules I've been using. Given a 4000' freezing level...and that there is only a 10% chance that snow makes it to the ground when the freezing level is at 2000'...and no chance when the freezing level is above that...and give the fact that snow completely melts when it falls through a warm layer of >3C...and the warm layer is going to be 4C...

I just have a hard time seeing it.

[Johnny]

Thanks for the explanation AFM. Here's what I don't understand. Why would the NWS even put up a chance of snow during this time period if they are looking at the exact same thing you are? I'm not doubting what you are telling us at all.

Let me put it this way...if you were the one giving out a forecast discussion for our area, would you even mention the possibility of some flurries?

I just don't understand that a degreed met with the NWS is saying that their is a chance of some flurries when he is looking at the exact same thing that you are. I mean he/she (since they are a degreed met, right?) should know that snow flurries are out of the question because the upper air columns just aren't matching up to produce snow flurries at the surface.


Seriously folks, I'm thinking the NWS is out to lunch on this one. I'll believe when I see it. I think the next time I will see snow is when I'm vacationing in the foothills of the Rocky Mountain National Park (Estes Park) in late spring. lol

[Air Force Met]

Thanks for the explanation AFM. Here's what I don't understand. Why would the NWS even put up a chance of snow during this time period if they are looking at the exact same thing you are? I'm not doubting what you are telling us at all.

Let me put it this way...if you were the one giving out a forecast discussion for our area, would you even mention the possibility of some flurries?

I just don't understand that a degreed met with the NWS is saying that their is a chance of some flurries when he is looking at the exact same thing that you are. I mean he/she (since they are a degreed met, right?) should know that snow flurries are out of the question because the upper air columns just aren't matching up to produce snow flurries at the surface.


Seriously folks, I'm thinking the NWS is out to lunch on this one. I'll believe when I see it. I think the next time I will see snow is when I'm vacationing in the foothills of the Rocky Mountain National Park (Estes Park) in late spring. lol

FIrst of all...no...I wouldn't even mention it...maybe if we had a 3000' mountain peak in northern Harris county....but otherwise...no.

Second...as for why? It honestly depends on your expertise. Our local guys are good as some things...but let's face it...winter forecasting hasn't even been their strong suit. It's a rare one that they nail and that is because they just don't do it that often. They may be falling into the same trap (and by reading the discussions...it seems likely) as many...only looking at the 1000-500mb thickness and the 850mb temps...which are two of the rules...but are the two quick rules to use and the easy ones to remember. All you have to remember is 540 and -01C. However, those indications tell you nothing about the temps in the air column...which actually determines the precip type. So...they just aren't used to forecasting for it. I've spent a lot of time forecasting for Ft Drum...Ft Carson (Colorado Springs)...Chanute AFB IL,...Voke Fld WI...Ft Riley, KS...Lots of snowy places. I have to use these rules a lot in the winter....plus I give seminars on them every fall to prepare my forecasters who will also have to forecast for wonderful Ft Drum...and points north.

It's like asking a NWS forecaster from Montana to give a tropical storm forecast...he's clueless...and rightly so. There's only so much weather stuff you can remember.

[Extremeweatherguy]

Just wanted to chime in and say that wxman57 over at KHOU has also said he thinks there is a chance of a few flakes tomorrow.

Seems like so many mets out there are giving this a green light as having a chance. AFM on the other hand continues to say it is a likely no go, and while he very well may be right.. at the moment I am hoping he ends up wrong this time! I want to see some snow!

I do want to thank you for your continued input though AFM! We know that you do not have to do this, and we appreciate hearing your professional opinion every now and then (even if I don't like what I hear sometimes). Please keep us up to date if any changes occur that would be more promising for snowfall!

[Extremeweatherguy]

Here are a few good radar links for those wanting to check in on the situation tonight/tomorrow:

http://wwwa.accuweather.com/radar-large ... al&large=1
^^Southern plains animated (accuweather)^^

http://wwwa.accuweather.com/radar-large ... 1&site=TXW
^^Texas animated (accuweather)^^

http://www.intellicast.com/IcastPage/Lo ... odnav=none
^^Texas animated not including panhandle (Intellicast)^^

As of this evening it looks like light snow is already falling in the panhandle. It will be that system to watch tomorrow morning.

[aggiecutter]

Portastorm, Bastardi is really going out on a limb by saying"possible Arctic air by mid January." That's kind of like saying "Thunderstorms are possible by mid April." If the Ensembles are right, the blowtorch is coming next week. It looks like the zonal flow will rule into the new year. Hopefully, Don's AO theory will come to fruition, and we will have a big pattern change by mid-month. If that were to happen, it would just be a matter of time before one those El Nino systems would meet up with the arctic air in the southern plains.

[Portastorm]

Portastorm, Bastardi is really going out on a limb by saying"possible Arctic air by mid January." That's kind of like saying "Thunderstorms are possible by mid April." If the Ensembles are right, the blowtorch is coming next week. It looks like the zonal flow will rule into the new year. Hopefully, Don's AO theory will come to fruition, and we will have a big pattern change by mid-month. If that were to happen, it would just be a matter of time before one those El Nino systems would meet up with the arctic air in the southern plains.

Aggiecutter, yeah I understand the level of skill it requires to say "possible arctic outbreak by mid January".

I was just summarizing. Of course he had lots and lots of details about the whys and hows, etc. I'll share more as I see but I know that others here also subscribe. I'm also reading Don's stuff closely, too. He's darn good!

Meanwhile, the rain just ended here in Austin. 31 straight hours of steady rainfall. The earth is rejoicing!

[JenBayles]

Great news about the rain Portastorm! We were up in Fredericksburg/ Luckenbach area in early November and couldn't believe how dry it was. We've never seen Grape Creek actually bone dry before. Hope it's running again now!

[Portastorm]

Portastorm, Bastardi is really going out on a limb by saying"possible Arctic air by mid January." That's kind of like saying "Thunderstorms are possible by mid April." If the Ensembles are right, the blowtorch is coming next week. It looks like the zonal flow will rule into the new year. Hopefully, Don's AO theory will come to fruition, and we will have a big pattern change by mid-month. If that were to happen, it would just be a matter of time before one those El Nino systems would meet up with the arctic air in the southern plains.

Aggiecutter, yeah I understand the level of skill it requires to say "possible arctic outbreak by mid January".

I was just summarizing. Of course he had lots and lots of details about the whys and hows, etc. I'll share more as I see but I know that others here also subscribe. I'm also reading Don's stuff closely, too. He's darn good!

Meanwhile, the rain just ended here in Austin. 31 straight hours of steady rainfall. The earth is rejoicing!

UPDATE: JB says 3 days of warmth followed by another wet system and then "much colder" by the weekend for Texas.

[double D]

I thought this was an intresting update from the San Angelo NWS:
Maybe some of this stuff will hit the Hill Country?

UPDATE...
KIND OF AN INTERESTING WEATHER SCENARIO SHAPING UP THIS CHRISTMAS
EVE. FAIRLY POTENT SHORTWAVE TROUGH IS DIVING SSE FROM THE
SOUTHERN ROCKIES INTO EASTERN NEW MEXICO AND THE WESTERN TEXAS
PANHANDLE THIS EVENING....AIDED BY A 90-100 KT JET STREAK ON THE
BACK SIDE. THIS SHORTWAVE TROUGH IS POSITIONED FARTHER WEST THAN
EARLIER MODEL RUNS HAD INDICATED. ASSOCIATED SURFACE COLD FRONT
EXTENDS FROM THE TX SOUTH PLAINS ACROSS EXTREME SOUTHERN NEW
MEXICO. WITH THE LEAD UPPER TROUGH SLOW TO EXIT...IT NOW APPEARS
THAT THE INCOMING SHORTWAVE TROUGH WILL DIVE FARTHER SOUTH ACROSS
THE WEST HALF OF TEXAS ...HELPING TO BROADEN THE UPPER LEVEL
TROUGH ACROSS TEXAS OVERNIGHT. EXPECT THE COLD FRONTAL PASSAGE
ACROSS OUR NORTHWESTERN COUNTIES BETWEEN 930 PM AND MIDNIGHT...
WITH THE FRONT SURGING ACROSS THE REMAINDER OF WEST CENTRAL TEXAS
JUST AFTER MIDNIGHT. AN INCREASE IN MOISTURE IS INDICATED BY THE
18Z GFS AND THE RUC MODELS WITH THE INCOMING SHORTWAVE...ALONG
WITH DECENT LIFT IN THE LEFT EXIT REGION OF THE UPPER LEVEL JET.
THE MOISTURE IS LIMITED BUT SYSTEMS LIKE THIS CAN WRING OUT WHAT
LITTLE MOISTURE IS AVAILABLE. THUS...WE ARE CARRYING LOW CHANCE
POPS FOR LIGHT PRECIPITATION LATER TONIGHT ACROSS MUCH OF WEST
CENTRAL TEXAS. THERMAL SOUNDING PROFILES SUGGEST RAIN AT THE
START OF ANY PRECIPITATION WHICH DEVELOPS. THEN WITH COLD AIR
ADVECTION THROUGH THE COLUMN AND WET BULB COOLING EFFECTS...WOULD
CHANGE TO SNOW FLURRIES OR SNOW SHOWERS OVERNIGHT (MAINLY AFTER
MIDNIGHT IN OUR COUNTIES). SATELLITE IMAGERY SHOWS CLOUDS DEVELOPING
ACROSS THE TX SOUTH PLAINS AND PANHANDLE...AND RADAR SHOWS LIGHT
PRECIPITATION DEVELOPING ACROSS THE PANHANDLE AND MOVING QUICKLY
SOUTH-SOUTHEAST. WE ARE NOT EXPECTING ANY PRECIPITATION IN WEST
CENTRAL TEXAS OVERNIGHT TO BE SIGNIFICANT OR CAUSE ANY TRAVEL
PROBLEMS.

[Air Force Met]

Just wanted to chime in and say that wxman57 over at KHOU has also said he thinks there is a chance of a few flakes tomorrow.

Seems like so many mets out there are giving this a green light as having a chance. AFM on the other hand continues to say it is a likely no go, and while he very well may be right.. at the moment I am hoping he ends up wrong this time! I want to see some snow!

I do want to thank you for your continued input though AFM! We know that you do not have to do this, and we appreciate hearing your professional opinion every now and then (even if I don't like what I hear sometimes). Please keep us up to date if any changes occur that would be more promising for snowfall!

Well...that's the good thing about saying "there's a chance"...if it happens...everyone thinks you forecasted the event (which you didn't...because you only said there was a chance...which means slight chance in this case)...and if you bust...you can say..."I said there was a chance...I didn't say it would happen...nor did I think it would."

BTW...looking at the 00Z soundings...the freezing levels are as follows:
CRP-8200'...WBZ is only 6mb lower.
LCH-9800'...WBZ-19mb lower.
DFW-6000'
AMA-1200'
MAF-6500'

So...freezing levels are still very high all over the state. I also just did some verification on the 12Z NAM run on the freezing levels and it seems to be pretty close...if anything the model was forecasting a lower freezing level.

The 12Z run had the 00Z freezing level for CRP at 7800'...and DFW at 5000'. Houston's was forecasted at 9500'...which seems about right. It looks like the GFS was right on track with the freezing levels. IT verified correctly at DFW and CRP. HOU's looked to be about 1500' too low. Forecast was 8000'...it's closer to 9500' now.

So...at 15Z tomorrow...the GFS is forecasting a 5500' freezing level...to 3000' near ACT...going to near 1500' near dfw. Using the rules, DFW would get 10% snow...90% rain with any precip....so mixed.

The NAM is calling for a 15Z freezing level of 5500' at Hou and 3000' at DFW...so...nothing at DFW but rain. By 21Z...the freezing level drops to 4500'...but by then the precip is gone.

[Air Force Met]

This is how hard it is for it to snow:

KCVS 250255Z 01029G38KT 9SM -RA FEW095 01/M01 A3019

It's still rain all the way up in Clovis, NM...at an elevation of 4000'...after a cold frontal passage and at 34 degrees F.

Now...come on...if it's too warm to snow in Clovis at 4000' up...does Houston really have a chance only 12 hours later?

[TexasStooge]

For 7 hours it was remained 45*F with light rain, and we're still anticipating a 20% chance of a mixed sprinkles and flurries precip. Of course, it shouldn't cause any business delays tomorrow, because most of us will be home on Christmas Day.

DALLAS/FORT WORTH
Tonight: 38°F
Christmas Day: 49°F

MERIDIAN
Tonight: 37°F
Christmas Day: 51°F

WICHITA FALLS
Tonight: 34°F
Christmas Day: 52°F

SAN ANGELO
Tonight: 33°F
Christmas Day: 51°F

AMARILLO
Tonight: 22°F
Christmas Day: 44°F