Southern Plains winter wx thread (2008-2009)

[iorange55]

The 00z GFS continues to show a massive push of arctic air entering the picture by mid month...

288 hrs - http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_288l.gif

300 hrs - http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_300l.gif

324 hrs - http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_324l.gif

348 hrs - http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_348l.gif

372 hrs - http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_372l.gif

This is still wayyy out there, but the GFS has to eventually be correct one of these times, right? lol.

BTW: That -10C line represents temperatures below 14˚F! If tonight's GFS run plays out, then Oklahoma is in for some COLD mornings come mid December with low temperatures likely bottoming out in the single digits.

Impossible without a snow pack...lol kidding.

[Extremeweatherguy]

Temperature at Will Rogers Airport as of 11pm = 24F
(12am = 26F)

Forecasted low (as of 5pm) = 35F

Forecasted low (as of 9pm) = 29F

We have shattered both of our forecasted lows for tonight, and it is not even midnight. Absolutely amazing!

[Valkhorn]

The 6z GFS is just insane for the lower Appalachians on day 13 and 14:



If there was any snowcover it would give us lows well below zero in East TN.

But look at the storm it's progging:



And with the potential at the TN Valley to get a ton of Snow:



It's been forecasting a serious turn to colder over the past few days but who knows if it'll be this extreme.

[jinftl]

With such an active southern jet and progressive pattern, plus the lack of large snowcover, not ready to buy a 336-hour forecast from the gfs. not ready to ever buy a 336-hour forecast from any model. trends can emerge, but specific temp and snowfall forecasts for a city are not the intention of such long range models to begin with.

The 6z GFS is just insane for the lower Appalachians on day 13 and 14:



If there was any snowcover it would give us lows well below zero in East TN.

But look at the storm it's progging:



And with the potential at the TN Valley to get a ton of Snow:



It's been forecasting a serious turn to colder over the past few days but who knows if it'll be this extreme.

[Ed Mahmoud]

6Z GFS has snow on the ground from near HOU to MSY in 11 to 12 days! I looked at my AccuWx PPV snowcover map, and almost cried tears of joy.




I won't get all shivers up my spine kind of excited until I see snow inside the 180 hours when the GFS has its best resolution.

-34ºF (-37º C) and almost 1040 mb at Bettles.

See Mr. Rivera's post above about learning to love brutal weather and high pressure in Alaska.

[vbhoutex]

6Z GFS has snow on the ground from near HOU to MSY in 11 to 12 days! I looked at my AccuWx PPV snowcover map, and almost cried tears of joy.




I won't get all shivers up my spine kind of excited until I see snow inside the 180 hours when the GFS has its best resolution.

-34ºF (-37º C) and almost 1040 mb at Bettles.

See Mr. Rivera's post above about learning to love brutal weather and high pressure in Alaska.

Now that is a the kind of look we need in the model if we are going to get winter precip in our area. Definite overunning developing to our S or SW and cold air in place. That way we can develop our own snow pack !!

Looking at all the modeling posted above it does appear we are going to get a very significant push of arctic air which will be coming down the face of the Rockies as opposed to heading more East.

BTW, Valkhorn was it your intention to use a model for the 17th and then models for the 10th-13th? I'm asking because those are two different events if I am reading this correctly.

[gboudx]

Ahhh, the good ole long-range GFS, and the unreliable 6z. Ready. Set. Kick.

[Extremeweatherguy]

In typical GFS fashion, the 12z run completely kills off the 6z run's December 12th Arctic outbreak. This run is only showing a 1018-1024mb high pressure system in Canada that is never able to move too far south, and thus the cold air can never make it into the lower 48. One bit of good news though, is that this scenario doesn't seem too realistic. I mean come on, a 1018-1024mb high pressure area!? That is extremely weak, and I doubt that is what will be developing over that cold air forecast to be up there at the same time. In actuality, we will probably see a much stronger high. The GFS will likely flip flop for several more days before we can get a clear picture of what will really happen in mid December.

[gboudx]

On another weather board I read, the 6z GFS is always scoffed and laughed at, and it's widely considered an unreliable run. And pretty much any run of the GFS beyond like 3-4 days should be taken with a grain of salt. But you guys know that.

[Valkhorn]

On another weather board I read, the 6z GFS is always scoffed and laughed at, and it's widely considered an unreliable run. And pretty much any run of the GFS beyond like 3-4 days should be taken with a grain of salt. But you guys know that.[/QUOTE]

It's far more accurate to say its an intermediate run. On the long range its probably only slightly less accurate. However on the short range it's still not too bad.

You don't look at the details this far out, you just look at the trend and what happens after the GFS treats a trough or two. Troughs change so many variables and the pattern thereafter sometimes in the model so you just have to look beyond that and see how the models handle things and go from there.

In the pattern we're in, it pays to be cautious.

As to the 12z run, it's not initialized past about 216 hours yet.

[jinftl]

I think that one of the realities of having so much more information available to us, the general public, is that the information will be misunderstood and not used as intended. Not to say that the public should be banned from accessing long-term models, but i don't believe any pro met would look at a run for 14 days out and make a specific temperature and precip forecast for a given location.

I know that with hurricane models, the margin of error rises to hundreds of miles once you get to 4 or 5 days out. There must be a similar margin of error with all of these GFS runs....and the results can produce huge swings from the given plot shown. That is probably why we see such flip flops from run to run at times...they are probably within the margin of error for so far out.

Information is good....and we can learn so much from what we have available via the internet compared to even 10 years ago....but there is that risk of not really understanding how to use the info we have at our fingertips.

On another weather board I read, the 6z GFS is always scoffed and laughed at, and it's widely considered an unreliable run. And pretty much any run of the GFS beyond like 3-4 days should be taken with a grain of salt. But you guys know that.[/QUOTE]

It's far more accurate to say its an intermediate run. On the long range its probably only slightly less accurate. However on the short range it's still not too bad.

You don't look at the details this far out, you just look at the trend and what happens after the GFS treats a trough or two. Troughs change so many variables and the pattern thereafter sometimes in the model so you just have to look beyond that and see how the models handle things and go from there.

In the pattern we're in, it pays to be cautious.

As to the 12z run, it's not initialized past about 216 hours yet.

[Valkhorn]

I think that one of the realities of having so much more information available to us, the general public, is that the information will be misunderstood and not used as intended. Not to say that the public should be banned from accessing long-term models, but i don't believe any pro met would look at a run for 14 days out and make a specific temperature and precip forecast for a given location.

I know that with hurricane models, the margin of error rises to hundreds of miles once you get to 4 or 5 days out. There must be a similar margin of error with all of these GFS runs....and the results can produce huge swings from the given plot shown. That is probably why we see such flip flops from run to run at times...they are probably within the margin of error for so far out.

Information is good....and we can learn so much from what we have available via the internet compared to even 10 years ago....but there is that risk of not really understanding how to use the info we have at our fingertips.[/QUOTE]

Agreed. I don't buy the 12z now that I looked at it. Not only are the arctic highs way too weak, but it's doing the same SW low song and dance routine common to the GFS runs in the winter.

[Extremeweatherguy]

Interesting tidbit from the Tulsa, OK NWS office this afternoon. Looks like they are hinting at the possibility of a winter weather situation next week here in Oklahoma...

THE NEXT SIGNIFICANT CHANCE OF PRECIP LOOKS TO OCCUR EARLY NEXT
WEEK...WITH A FAIRLY SUBSTANTIAL WAVE DEVELOPING AND SWINGING
THROUGH THE AREA. ALTHOUGH GFS AND ECMWF ARE LARGELY IN AGREEMENT
ON THE TIMING OF THIS FEATURE...THE EFFECTS ARE IN SUBSTANTIAL
DISAGREEMENT. THE ECMWF BRINGS A FULL FLEDGED FRONT DOWN...WITH
850 MB TEMPERATURES DROPPING TO SUBZERO LEVELS...WHILE THE GFS
ACTUALLY BRINGS A WARM UP IN THE WAKE OF THE TROUGH. THE ECMWF
SOLUTION SEEMS MORE PLAUSIBLE AND ALSO HAS THE SUPPORT OF PRIOR
ECMWF RUNS...AND AS A RESULT...MEX GUIDANCE NUMBERS HAVE BEEN
UNDERCUT FAIRLY SUBSTANTIALLY ON DAY 7.

If the ECMWF is correct and the GFS is wrong, then things could definitely get interesting early next week!

[Valkhorn]

If the ECMWF is correct and the GFS is wrong, then things could definitely get interesting early next week![/QUOTE]

I think the ECMWF will be more accurate since the GFS keeps waffling too much and producing anomalous results. On the 18z, it's pouring a bit of cold air into the US in the long range but the details keep appearing to be muddy. I don't expect it to clear up until this weekend unfortunately.

[iorange55]

GFS 00 still showing the winter storm but it pushed it back a little I think. I hate waiting.

[Extremeweatherguy]

The 00z GFS decided to flip back to targeting December 15th as the arrival of the arctic air in the south. Between the 15th and 18th of December, this run shows one heck of a cold and snowy/icy pattern across the southern plains. Pretty fun to look at, but obviously not something to be taken seriously given its long range nature. One thing that is interesting to note though is that despite the constant flip flopping on the timing, the models do seem to be in some sort of general agreement that an arctic airmass will try and come south at some point between December 10th and 20th. Exactly how cold this airmass winds up being and whether or not there is moisture involved is yet to be seen though. Hopefully in about 7-10 days from now (when the timeframe is closer) we will have the answers to these questions.

[Extremeweatherguy]

The front coming south tonight is a WILD one! The temperature in McCook, NE jumped from 51F to 62F prior to the front's arrival and then plunged to 45F right after it passed through. Now, just a couple of hours later, it is 35F in McCook with cloudy skies and northerly winds gusting to 36mph (generating a wind chill of 21F)! Brr.

Further south, in Goodland, KS, the front is also playing games. At 8:53pm they were sitting at 32F, but within two hours they had surged to a balmy 51F! Now, with the front just having passed through, Goodland has fallen back to 39F with wind gusts to 48mph and a wind chill of 27F! Pretty insane.

I can't wait to see what this front does when it reaches Oklahoma tomorrow morning. Sounds like it might be a fun one.

[iorange55]

The front coming south tonight is a WILD one! The temperature in McCook, NE jumped from 51F to 62F prior to the front's arrival and then plunged to 45F right after it passed through. Now, just a couple of hours later, it is 35F in McCook with cloudy skies and northerly winds gusting to 36mph (generating a wind chill of 21F)! Brr.

Further south, in Goodland, KS, the front is also playing games. At 8:53pm they were sitting at 32F, but within two hours they had surged to a balmy 51F! Now, with the front just having passed through, Goodland has fallen back to 39F with wind gusts to 48mph and a wind chill of 27F! Pretty insane.

I can't wait to see what this front does when it reaches Oklahoma tomorrow morning. Sounds like it might be a fun one.

I'm confused, why do the temps rise right before it comes? Do south winds pick up or what?

[Extremeweatherguy]

I know, it is pretty confusing. What is really weird though is that the winds did not switch to the south during the temperature rise. Instead, they actually increased from the north, which seems to defy logic.

[vbhoutex]

I know, it is pretty confusing. What is really weird though is that the winds did not switch to the south during the temperature rise. Instead, they actually increased from the north, which seems to defy logic.

They may not have switched at the surface, but I imagine they did above the surface, otherwise there would have been no reason for that temperature rise, I don't think. If someone more knowledgeable can explain this please do.