Southern Plains winter wx thread (2008-2009)

[jinftl]

There is always cold in Siberia & Alaska this time of year....no need to be planting '1989' seeds....the question is and will always be, what happens to arctic airmasses as they move south. Even record cold arctic airmasses are not a 'sure thing' once you get south of 35 deg latitude. We are seeing this now..as even the most ardent supporters of the '89 cold snap we should be seeing this weekend (as per some models a week or 2 ago) are coming around to admitting....the next front may not get south of dallas....maybe it will, maybe it won't. All the while, the airmass will be moderating over the lack of widespread, deep snowcover south of the upper plains and midwest.

If this winter follows what happened after the December 2004 snowfall in Houston....it will be an anti-climax. Winter of 04/05 saw 20 nights in which Houston (IAH) dropped to 39 deg or lower at night. 12 of those took place in December 2004.

Does this early season snow event fortell even more winter weather to follow? Surprisingly, nope. Prior to yesterday, there have been 7 December snow events (at least a trace) in Houston (airport data) since 1895. How much snow must have fallen in the January and February that followed? None. 0 of the 7 December snowfalls were followed by additional measureable snow for that winter season (defined as Dec-Jan-Feb). But I am the first to admit...there is a first time for everything, but if I was responsible for Houston's budget....i would recommend that in these lean times, snow plows can probably go without being bought at least another year...or 4.

And don't even look at what happened in Janaury 1990....the 'ying' to the 'yang' of the December 89 cold snap. Houston averaged 9 deg above normal for the month (keep in mind...Dec 1989 was only 8 deg below normal for Houston).

Cold in Siberia, but pressures aren't particularly high.




They didn't have all the cool stuff in the word wide interweb they do now back in 1989, so I don't know what kind of surface pressures and temps in Siberia I need to be looking at. Alaska doesn't seem particularly cold.


Looking around Wunderground, -65ºF (-54ºC) is coldest I can find in those parts, Yellowknife is below -30ºC.

[Extremeweatherguy]

The 00z GFS run continues to erode the cold air way too fast next week.

[southerngale]

Y'all can speculate all day long, and I'll continue to read it and learn, but while everyone was discussing next week's winter weather threat, a record-setting snow sneaked up on some of us. I was reading about the possibilities for next week, when suddenly we were a day or so away from possible snow! My only point is boy... it can sure sneak up on you! If anyone predicted this a week or two ago, I missed it.

Snow sure is a lot of fun. I still have a little left in my yard, and I'm already ready for more. lol

[Ed Mahmoud]

I think we're now close enough, we'd know if 1989 was coming. Or at least have an idea, and I'm not getting that feeling it is coming.


But ice storms in Dallas are not that uncommon. In my unscientific recollection of Winters in the Metroplex in the 80s and 90s, ice was almost a once a winter phenomena.

I saw snow twice, once accumulating on elevated surfaces (including highways), and freezing rain twice in six years in Austin.

[Ed Mahmoud]

Y'all can speculate all day long, and I'll continue to read it and learn, but while everyone was discussing next week's winter weather threat, a record-setting snow sneaked up on some of us. I was reading about the possibilities for next week, when suddenly we were a day or so away from possible snow! My only point is boy... it can sure sneak up on you! If anyone predicted this a week or two ago, I missed it.

Snow sure is a lot of fun. I still have a little left in my yard, and I'm already ready for more. lol

Friday morning I was speculating (based on Canadian and GFS) we might see a mix. It didn't look then from soundings from WxMaps.org meteograms and AccuWx PPV raw numbers it'd stick, but it wasn't a complete surprise

name changed to protect innocent Post subject: Re: 2008-09 Texas Winter Weather ThreadPosted: Fri Dec 05, 2008 7:52 am
Professional-Met

Joined: Sat Jun 21, 2003 8:06 pm
Posts: 7161
Location: Houston, TX

Ed Mahmoud wrote:
A flake or two mixed in with the showers near HOU Wednesday morning?

http://www.meteo.psu.edu/~gadomski/AVN_0z/f132.gif

Unlikely. The airmass won't be cold enough and the moisture will shut down. The 00Z European continues the trend of cross-Polar flow and some very cold air coming down around the 15-18th. GFS is lost, it can't handle the pattern.

[iorange55]

So there are still no models that allow you to type in what you want to happen and then it makes it happen correct?

[Ed Mahmoud]

So there are still no models that allow you to type in what you want to happen and then it makes it happen correct?

This is my first Winter of w!sh casting winter precip for HOU, and look how well it turned out.

[Extremeweatherguy]

I recently found a site that talks all about Model biases: http://www.hpc.ncep.noaa.gov/mdlbias/biastext.html

I found the section on medium range models to be particularly interesting. Here are a few of the key points...

-Models (short and medium range) do not drive arctic fronts fast enough and far enough south through the Great Plains in the winter. ECMWF usually has the best handle on such fronts of the medium range models, but is still usually a bit too slow.

-Arctic air will plunge southward at a more rapid pace to the lee of the Rockies and the Appalachians than forecast by medium range models (especially the UKMET) or most short range models.

-Surface development is overdone in an arctic airmass by all models.

-Model surface lows over land are often too deep.


Also, under the ECMWF section, it states the following...

-Outperforms the other medium-range forecast models during shallow cold air situations.

-Of the medium range models, the ECMWF performs best with driving Arctic fronts down the east slopes of the Rockies.


This definitely helps to reinforce the idea that the models are probably continuing to have problems with next weeks event. In all likelihood, the cold air will arrive sooner and move further south than currently shown by the models.

[iorange55]

I recently found a site that talks all about Model biases: http://www.hpc.ncep.noaa.gov/mdlbias/biastext.html

I found the section on medium range models to be particularly interesting. Here are a few of the key points...

-Models (short and medium range) do not drive arctic fronts fast enough and far enough south through the Great Plains in the winter. ECMWF usually has the best handle on such fronts of the medium range models, but is still usually a bit too slow.

-Arctic air will plunge southward at a more rapid pace to the lee of the Rockies and the Appalachians than forecast by medium range models (especially the UKMET) or most short range models.

-Surface development is overdone in an arctic airmass by all models.

-Model surface lows over land are often too deep.


Also, under the ECMWF section, it states the following...

-Outperforms the other medium-range forecast models during shallow cold air situations.

-Of the medium range models, the ECMWF performs best with driving Arctic fronts down the east slopes of the Rockies.


This definitely helps to reinforce the idea that the models are probably continuing to have problems with next weeks event. In all likelihood, the cold air will arrive sooner and move further south than currently shown by the models.

Interesting stuff!


Looking at the new ECMWF it does not look good at all eh? Least by comparing it to it's earlier runs.

[Extremeweatherguy]

The 00z ECMWF continues to drive the arctic front south through Texas by Sunday into Monday, but then looks strange at 120 hours. It, like the GFS, develops a random low right near the Texas panhandle on Tuesday. This low then goes on to last <24 hours before suddenly disappearing. It doesn't make much sense. What the low does manage to do in its short lifespan though is try and lift some of the cold back north. The biggest question in my mind after seeing this is: Will the low really be there? If it isn't, then the cold air will probably stay settled over the southern plains instead of trying to retreat north.

Hopefully we will have more answers by the weekend! What a confusing mess this all is! We probably will not know what is really going to play out until after it has already happened. lol.

[iorange55]

Best quote I could find from the Noaa Discussions today.


From Tulsa.

WAIT AND SEE IS ABOUT THE ONLY
REASONABLE ACTION AT THIS TIME.

Wait and see.

[Portastorm]

Seen some excellent posts here this morning. I couldn't agree more with Southerngale ("While we were focused on a potential Arctic outbreak next week, a historic event (snow along the Gulf Coast) snuck up on many of us") and Ed's comment about ("If 1989 were coming next week, we'd know by now").

Based on the last few runs of both the Euro and GFS, next week doesn't appear to be much to get excited about at all ... that is for those of us south of the Red River. EWG may get some nasty stuff in OKC for sure.

[jasons2k]

I have to concur with most of today's comments - basically:

1) It's gonna get cold next week
2) The GFS is too warm
3) Threat of winter precip for DFW and OKC areas, probably just cold rain along the coast
4) This will be nothing like 1989 or 1983 (surprise, surprise - whoda thought?)

In summary, just a typical mid-December arctic front for the southern plains. Nothing apocalyptic or anything like that. Wash, rinse, repeat

[Extremeweatherguy]

Latest from Norman...

.DISCUSSION...
COMPLEX FORECAST NEXT SEVERAL DAYS. MAIN IMPACTS...STARTING WITH
STRONG WIND AND EFFECTS ON FIRE WEATHER LATE TODAY THROUGH SUNDAY.
WIND ADVISORY LEVEL WINDS LIKELY SATURDAY AND POSSIBLY AGAIN
SUNDAY...AHEAD OF INCOMING ARCTIC FRONT AND EVEN BEHIND IT. RH
VALUES IN THE FORECAST DO NOT GET BELOW 20 PERCENT EITHER DAY...BUT
WITH WARM CONDITIONS AHEAD OF FRONT AND VERY STRONG WIND...FIRE
WEATHER CONDITIONS WILL BE A CONCERN.

ARCTIC BOUNDARY STILL PROGD TO MOVE ACROSS THE REGION SUNDAY AND
SUNDAY NIGHT. WILL CONTINUE WITH THE FASTER NAM SOLUTION...WHICH
STILL GIVES MOST OF THE REGION A RELATIVELY MILD SUNDAY BEFORE THE
BOTTOM DROPS OUT SUNDAY AFTERNOON AND EVENING. MODELS...ESPECIALLY
THE GFS...WANT TO ERODE COLD DOME TOO QUICKLY SO FORECAST TEMPS WILL
REMAIN 20 TO 30 DEGREES COLDER THAN MUCH OF THE GUIDANCE THROUGH
MID-WEEK. TOWARD THE THURSDAY AND FRIDAY TIME FRAME...EVEN THE ECMWF
SUSTAINS ENOUGH LOWER LEVEL WARM ADVECTION TO ERODE BULK OF ARCTIC
AIR OVER SOUTHERN AND WESTERN PARTS OF FORECAST AREA. BASED ON
DPROG/DT...NONE OF THE MODELS ARE PARTICULARLY STABLE WRT RUN TO RUN
CONSISTENCY. AS MENTIONED BEFORE...WE WILL KEEP FORECAST MUCH COLDER
THAN GFS/MEX GUIDANCE BUT WILL HAVE TO RAISE TEMPS A LITTLE IN THE
OUTER PERIODS TO KEEP NDFD CONSISTENCY AT LEAST SOMEWHAT REASONABLE.

IT STILL LOOKS LIKE OUR FORECAST AREA WILL AVOID MAJOR ICE
ACCUMULATIONS...ALTHOUGH PERIODIC LIGHT ICING LIKELY OVER AT LEAST
PART OF OKLAHOMA AND NORTH TEXAS. JUST A LITTLE ICING GOES A LONG
WAY...BUT IF CURRENT MODEL FORECAST ARE ANY INDICATION...WE SHOULD
AVOID A REPEAT OF LAST YEARS DEVASTATION. LATEST MODEL SOUNDINGS
INDICATE THAT THE PREDOMINATE PRECIP TYPE ACROSS THE NORTHERN THIRD
OR QUARTER OF OKLAHOMA WILL BE SNOW OR SLEET...WITH FREEZING PRECIP
SOUTH OF INTERSTATE 40. HOWEVER...ONCE WARM NOSE DEVELOPS ATOP COLD
DOME BY TUESDAY...WE COULD SEE CONCERN FOR LIGHT FREEZING
PRECIPITATION SPREAD BACK NORTH TOWARD THE KANSAS BORDER. TRIED NOT
TO GET FANCY AND KEPT CLOSE TO PREVIOUS FORECAST DEPICTIONS.

[Extremeweatherguy]

Latest from Joe Bastardi: He thinks the models are having a hard time with next weeks pattern and won't really start looking good until they "see" how much cold air there is. He thinks the idea of the arctic front blasting through Dallas on Monday and then seeing above normal temperatures there by Wednesday is not very likely.

[Ed Mahmoud]

What happened Christmas week 1984? I was stationed in Upstate NY then, and it snowed often enough no single snow stands out in my mind.


Except the time I was driving slow and careful, in snow, and gently applied the brakes long before the red light, giving myself double or triple the stopping distance, and glided right through a major intersection against the light, and lived to tell about it.


And the 360º I did on an narrow 2 lane icy bridge in my 1976 Chrysler Cordoba (same car as the red light runner) and didn't hit anything. And wound up facing the right direction.

[Ed Mahmoud]

WRF
Front hits OK City dinner time Sunday.


Reaches the Texas coast Monday around lunch. but I don't think a 1040 mb high (if the model is right) back in Canada has quite enough ooomph to really cause an Arctic outbreak.

Still cold enough to support some ice or sleet well behind the front, although the WRF looks pretty dry.

[Extremeweatherguy]

Well there is already a 1046mb high up in Alaska right now (http://www.hpc.ncep.noaa.gov/sfc/90fwbg.gif), and it is expected to grow a little more over the next few days. The 6z GFS bringing it up to 1052mb in 48 hours: http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_048l.gif

Now it could weaken rapidly to 1040mb next week as the models try to show, but I would think it would remain a little stronger. We shall see.

[Extremeweatherguy]

12z GFS = Colder and wetter.

Compare next Tuesday afternoon...

12z run = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_102l.gif
00z run = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_114l.gif

Not looking good for Oklahoma. Lots of ice problems if this run is correct.

[jasons2k]

Not looking good for Oklahoma. Lots of ice problems if this run is correct.

Oh come on EWG, just admit it, you can't wait