Oklahoma Weather Discussion - February/March 2013

[venture]

00Z NAM is in for the Winter Storm next week. It continues to maintain nearly all snow to the NW quarter of OK with a little spill over into far NC OK. Snow amounts generally 3-6" over most areas. So I wanted to show how this has evolved. The last 6 runs of the NAM have shown...

Date = Model initialization date, not forecast day
18Z Feb 09 - Winter Mix, < dusting of snow North Central and far NE.
00Z Feb 10 - Snow mainly along and north of Altus to Pauls Valley to Fort Smith line. Generally 1-3", 3-4" Central back to NW, and far NE OK.
06Z Feb 10 - Snow all but far southern and SE OK. 6-10" Western OK into Central OK. 3-6" around that area in most locations and 1-3" NE.
12Z Feb 10 - Snow only NW quarter of OK. 6-9" of snow from Enid to Clinton and back west.
18Z Feb 10 - Snow NW quarter into NC OK. 3-6" most areas.
00Z Feb 11 - Snow NW quarter into NC OK. 3-6" most areas.

So we always want to look at consistency. The last three runs have been pretty much on the nose when it comes to being consistent. So what about OKC area?

Start around 6-9AM Tue - Rain/Sleet mix
9AM through 12PM - Rain, maybe some sleet here and there.
12PM - 9PM - Rain with some snow mixing in
9PM - 12AM - Sleet/Snow
Weds 12AM - 3AM - Snow ending

Now one thing to point out is that precip may stick around 6-9 hours longer that previous forecast. Snowfall amounts will be mitigated by warm and wet ground. Though if there was any accumulation we are looking at 1-2" North of I-40, dusting south of I-40 for the OKC metro area. Total rain fall outside of the snowfall potential (for the periods before change over) looks like around a 0.4" to 0.75" inch of rain...more NW side, less SE side.

Upper air profiles with NAM continue to be borderline, in my opinion, that just a couple degrees cooler or an additional 500-800 feet of below freezing air above the surface can turn this from a 1-2" snowfall for some in Central OK, to a 6-10" snowfall...if we went on a straight 10 to 1 ratio. Though with the air temps as borderline as they are, snow will probably be fairly wet and there will be an influx of graupel and sleet which will hold totals down as well. Plus we also need to take into consideration as the precip falls it could, by itself, cool the air further to make a transition happen sooner - if at all.

Clear as mud? Good.

[s00nr1]

Venture, you nailed it on the head with that summary. Here is a graphic that illustrates that very detailed overview:



It should be noted that the NAM was the last model to latch onto this system and was also the furthest off 36 hours out in regards to the Christmas storm.

[s00nr1]

0z GFS coming in.....digs the storm much further south than the NAM bringing accumulating snows into W and C OK.

[venture]

Mmhmm. It has a bullseye of the heaviest snow from like El Reno out to Weatherford of around 6" of snow. Just cementing my earlier points. We'll know what will happen probably Tuesday evening.

[Plutonic Panda]

Mmhmm. It has a bullseye of the heaviest snow from like El Reno out to Weatherford of around 6" of snow. Just cementing my earlier points. We'll know what will happen probably Tuesday evening.

A bit optimistic there venture ;P

[venture]

A bit optimistic there venture ;P

Just reinforcing my point that I really think this is a setup to bust a lot of forecasts. If the temp swings 2 degrees cooler it is a completely different story for central OK.

Example...



That is the Norman forecast sounding for 15Z / 9AM Tuesday. The red line is air temp. The zero at the bottom is in Celsius. So follow that line up diagonally to the right and you see that the air temp reaches freezing right around...1200-ish feet up. If the cold air is deeper (lower to the ground) than forecast or the a couple degrees cooler from that 1200 feet and down to the surface - it's all snow.

[Plutonic Panda]

Yeah I know, I'm just joking haha... I was thinking we wait till' wednesday to see what really happened seeing as this is Oklahoma lol...

[s00nr1]

As my thoughts last night were alluding to.....the NAM is now pulling the storm a bit further south and east -- as it did at the last second for the Christmas Day storm -- bringing some decent snowfall amounts into the OKC metro:

[Anonymous.]

This is going to be close...

I think the models were (still are) underestimating the cool/cold air that will be filtering down into OK tonight. The Central and Northern plains just got a blizzard dumped on them and the air is extra refrigerated as it moves south.


I agree, that this looks just like the Christmas Day storm that busted for most of OK; last minute changes in track after days of consistency.

Like I said on page 2 of this thread, the storm looks like it is going to track very similarly to the 09 Christmas Eve storm that dumped 14 inches on OKC. This time the ground is not as cold and the overall temperatures wont be as cold, and this will be a very wet snow event.

Will have to monitor the wet-bulb temperatures tomorrow as the preceip moves in, this is a tough forecast.

[s00nr1]

While I agree to an extent, the one issue I see with that is the southerly to calm surface winds across much of Kansas tomorrow morning. One thing to keep an eye on tonight will be to see the strength and direction of the surface winds across southern Nebraska and northern Kansas to get an idea of whether that cold air might have a chance of filtering down into this system tomorrow.

[Anonymous.]

I am definitely looking through my snow goggles at the moment, but if the skies can stay clear for a majority of the night tonight..... o boy!

[kelroy55]

Channel 4 is saying just a dusting here.

[Anonymous.]

Channel 4 is saying just a dusting here.

Yea the locals will go with the NAM on this and keep OKC in rain. Will be interesting to see their same forecasts tonight...

Storms that come down to a handful of degrees will make you go insane trying to forecast.

[s00nr1]

12z GFS again inching things further south and east toward the OKC metro.....will load up snowfall maps here in a bit.

[venture]

GFS continues with its trend of heavier snow from West Central to Central OK. Like I said a couple days ago, they just need to blanket a winter storm watch for much of the area and let it play out from there. Awareness will be there, but this is going to be a last minute call.

[s00nr1]

One thing is certain, precip will not be an issue (even with the faster-moving GFS solution):

[s00nr1]

Yeah, Venture, I would be shocked if OUN hasn't expanded the WSW into central OK by early this afternoon.

[venture]

Norman slightly adjusted the accumulating snowfall a bit further south.

[s00nr1]

In my meteorology classes at OU, we used to call this a "snow hole":

[SomeGuy]

I have an odd feeling that Oklahoma city is going to get snowed on. I remember when they said nothing would happen on december 28th of 2012 and turns out we got a few inches of snow

[kelroy55]

I have a jeep so I won't be snowed in

[venture]

I have a jeep so I won't be snowed in

Having a Jeep and knowing how to drive it in snow are two different things.

[SomeGuy]

I have a jeep so I won't be snowed in

My dad had a jeep for several years and even it had a hard time in the snow due to lack of certain tires, I hope you have snow tires or whatever they are called.

[ou48A]

Having a Jeep and knowing how to drive it in snow are two different things.

Exactly… And I have seen snow way too deep for a Jeep.............................................. ....................... in Kansas.

[s00nr1]

Looking at the 12z GFS....another snowfall might be possible Friday afternoon/evening with a fast-moving NW flow system.