December '09 Weather Discussion

[venture]

Well with very little activity, November has come and gone. December though appears to be getting a bit more rambunctious, especially by the 2nd week. Strong system will move in next Saturday. Mild air ahead of it into the 50s, but behind the arctic express arrives. Still a long ways out, but this is how it is appearing right now.

Friday 12/4 - Low ramps up in SE CO. Air ahead of the system will be in the 40s/50s through most of OK. System will be starved for moisture it appears for now.

Saturday 12/5 - Temps will rise overnight as the storm system approaches Central OK. Some areas will get close to 60 by morning, especially SE OK. System continues moving SE through the day and into NE TX by evening. Temps behind the system will be in the mid to upper 30s over the western 2/3rds of OK. Scattered rain will develop in the eastern half of Oklahoma. Central OK looks dry except for the chance of some wrap around moisture that may bring some light snow/flurries to the area.

Sunday 12/6 - Temps overnight fall below 30 roughly along and north of I-44. During the day temps will rise to 30-38 along and west of I-35, but will remain below 30 for most of Western OK. Next batch of moisture works in late. Scattered rain/snow will develop in the panhandles and move into Western OK late.

Monday 12/7 - Temps will remain fair stagnant at the cold air mass sets in. Temps will not break 30 across most of the state, except for SE OK. Precip continues moving to the east. Wide swath of moderate precip amounts will development in the northern 2/3rds of OK. This area will begin to weaken by evening, but indicates a possible precip band setting up along and 30 Miles North and South of I-44. The morning precip batch looks like a swatch of 0.25 to 0.40" of precip. If this is all snow, we'll look at probably 1-3" maybe some areas of 4 to 5". Evening snow band will likely lay another 1-2" of snow in the area mentioned. Total precip will be around 0.25 to 0.6" of liquid precip. If it stays all snow...maybe some good areas of 3-5" with a couple higher amounts. If it stays liquid, we'll probably see an icing event considering the air temps will be below freezing.

Tuesday 12/8 - Models only through Tues AM. Temps will fall into the teens along and north of I-44. 20s elsewhere. Another major shot of cold air drops through the rockies with temps well below zero in many areas. The panhandle will only see single digits overnight it appears. No precip expected today the way it looks now.

We'll need to watch it, but may be our first shot of some accumulating snow this season - just in time for the holiday season.

[PennyQuilts]

Ahem. Didn't I tell you to not let any bad weather in the second week of December????

[venture]

Amg. I...was...planning on driving up to the great lakes that week. LOL Let the scramble begin to find an air fare that works.

[Thunder]

I want a White Christmas, please. It only count if snow is actually falling and everything is completely covered.

[PennyQuilts]

Just please make it snow, not ice.

[westsidesooner]

I vote for snow too, if it's going to be cold it might as well be pretty. It seems like years since our last "good" snow, and the snow shovels I bought for that haven't been much help with the ice. lol With Christmas being on a Friday this year it would be great to get a Christmas eve snowstorm that lasts through the weekend, then melts for the next Monday. It snows so little around here anymore I feel sorry for anyone who has recieved a sled in the last 10 years for Christmas.

You still sticking with your prediction for early next week V? And btw thanks for the long term forecasts..........very helpful and in the past very accurate.

[PennyQuilts]

Christmas Eve snowstorm is okay cept one of my daughters is coming in. Make it after 11:00 pm.

[westsidesooner]

Then let the first snow flakes start falling as she arrives at your door. 11:01 is fine with me. Getting together with family is the best part of Christmas......

[PennyQuilts]

Thanks, WSS!

[venture]

Wanted to quickly hit on short term winter weather chances. Model "A" - Precip spreads north early Weds morning through afternoon. Mainly along and south of I-44. Clearing out during the evening. Surface temps will remain around 40-43 across most of the state. Cold air does filter in, in the upper levels, by 7-9AM Weds...so there might be some snow mixing in. However nothing will stick.

Model "B" - Precip develops in the same time frame, but extends a but more to the north. Moves out of Central Ok by early afternoon. Similar to model "A"...cooler air upstairs moves in by afternoon, but precip may be ending. Some snow might mix in, but again...nothing sticks.

On to the weekend and next week. Things are modified a bit, but swings in model output will always be crazy this far out.

Sunday - Precip starts to develop across Central OK around sunrise. This will be light and in response to a system moving along the Red River. Temps will be below 35 at this time, so precip may be a winter mix of rain and snow or perhaps all light snow. Light precip continues are temps hover in the mid to upper 30s. Total precip accumulation during this time will be less than a tenth of an inch of water, or less than an inch of snow (if all snow).

Monday/Tuesday - Dry Monday highs in the low to mid 30s. Tuesday next system gets ready to move in. System will move out of the Rockies Tuesday. Temps early Tue will start in the upper 20s to low 30s across most of the state. By afternoon, temps will rise in the low 30s northern half of OK, mid 30s Central...and low 40s south. Precip starts light in the morning and picks up during the day. By afternoon moderate precip will develop across most of OK except extreme SE OK. Northern half of OK spreading down to Lawton and Pauls Valley, will see precip amounts up to a quarter inch of liquid. Upper air freezing line will be roughly in the same area.

Wednesday: Temps will fall below 30 in all by extreme SC and SE OK. Precip will continue with very light amounts west to light and moderate amounts as you go east. Central sections may see another tenth of an inch of precip and up to a quarter inch NE. Precip ends quickly in the afternoon. Highs will remain in the upper 20s in Central and N OK, with low 30s in southern areas. Precip may start out as a mix in central areas, but will transition to all snow.

Total snowfall amounts looks like they will pretty light. Depending on the change over from rain to snow, through Tuesday evening NW OK will pick up 1-2" of snow, around 1" in the rest of Northern OK, and less than an inch in Central OK due to extended periods of liquid precip. Wed AM through PM...Dusting/Flurries in W OK, about 1" in Cental OK, and 1-3" in the NE quarter of OK. Right now Central OK is looking at maybe an inch, if change over happens faster Tuesday... 1-3".

Thursday: Quick moving system drops out of the rockies, not a lot of precip right now with it, but light snow providing a dusting may move across NW OK.

[PennyQuilts]

Thanks Venture. Try to keep the 13 - 15th in good shape, whill ya?

[venture]

Thanks Venture. Try to keep the 13 - 15th in good shape, whill ya?

I tryin'...I tryin'. ;-)

Tonights run seems to have bounced back over to a higher precip solution.

Sunday - First effects come in late Sunday, mainly east of I-35 with very light and isolated precip. Temps will mainly be in the Mid 30s to Low 40s. So this should be mostly rain or flurries if it is snow anywhere.

Monday - Quiet. Highs in the Upper 20s NW to Low 40s SE.

Tuesday - Storm organizes in CO and starts to spread light precip early Tuesday north of I-40 and west of I-35. Precip amounts increase north of I-40 throughout the day, with some light amounts south. First wave moves out late Tuesday. Next shot comes into SW OK around the same time as the surface low moves just south of the Red River. During the day there will be some warming. Temps in the northern 1/3rd of the state will remain below freezing. Central sections will bounce back and forth by will be a few degrees around 35 the way it looks. By Weds evening, freezing line should be just along I-44 and moving SE. In an area North of I-40 and North of I-44...snowfall amounts, the way it looks now, will be in the 1-3" range. Higher amounts in North Central OK where we could see some isolated 3-6" totals. SW Oklahoma, in some areas, can see 1-2" just north of where the freezing line sets up.

Wednesday - Overnight, low will move past and an enhanced area of precip will develop across OK. Heaviest area right now looks to be in Central OK (metro) extending NE to Tulsa. This are should push out quickly and be gone by mid morning. Temps by midnight should be below 30 across all but extreme SE OK. Temps in Central sections will be in the mid 20s. If precip develops as is current indicated, this will setup a band of 3-6"...right now that appears to be around the OKC Metro to just SW of Tulsa. Areas except far NW OK and far SE OK should at least see 1-3".

Snow banding is extremely difficult to forecast more than like 6-12 hours out...so this is a total crap shoot. A lot of the times this type of setup for the Weds period won't materialize as all the energy transfers to the east too fast. During this time the surface low will be picking up strength in Alabama and racing to the east. Severe weather is going to be a big risk out that way, but we are entering their season for it. This system does appear to be on its way to setup a somewhat classic Nor'easter, though positioning looks to be a bit off right now.

13-15 are looking some what okay right now. Does look like precip east of the Mississippi on Sunday the 13th. However, long ways out, so will hold off on that.

Anywho. It does seem SOMETHING will happen next week. The magnitude is really hard to forecast until we get closer. This is one of those things, if the cold air doesn't establish itself...it will be wet and that'll be that. If the cold air does settle in, we may have to shovel a bit. The Christmas lights will look nice though if that happens.

[venture]

NWS Norman's comments this morning on the crazy low temps. The models have been kind of stubborn with these though, so we'll see what happens.

THERE ARE SOME SPECIFIC MODEL DIFFERENCES AFFECTING FORECAST
TEMPERATURES EARLY NEXT WEEK. GFS ENSEMBLE MODEL SPREAD IS
RIDICULOUS WITH LOW-LEVEL TEMPERATURES EARLY NEXT WEEK. H8
TEMPERATURES AT 00Z/WEDNESDAY HAVE A SPREAD OF 16.5 DEGREES C AT
OKC /FROM -7.5 TO +9/ AND 23 DEGREES C AT GAG /-13 TO +10/.
GFS ENSEMBLE GRIDDED SURFACE MAX TEMPERATURE FIELDS ALSO SHOW A
HEALTHY RANGE FOR TUESDAY AFTERNOON WITH VALUES FROM 26 TO 58 AT
GAGE AND 33 TO 66 AT WICHITA FALLS. SOME OF THIS DIFFERENCE IS
EXPLAINED BY JUST WHERE THE SURFACE FRONT AND THE TEMPERATURE
GRADIENT IS LOCATED AS ALMOST ALL MEMBERS /AS WELL AS ECMWF/ SHOW
COLD AIR MOVING AT LEAST INTO THE CENTRAL PLAINS... BUT THIS
SPREAD GIVES LOW CONFIDENCE IN ANY PARTICULAR SOLUTION THIS FAR
IN ADVANCE. WITH THE SIGNAL OF COLD AIR MOVING SOUTH THROUGH THE
PLAINS... WILL LOWER TEMPERATURES IN THE EXTENDED... BUT NOT
NEARLY AS LOW AS MEX MOS NUMBERS AS THE OPERATIONAL GFS IS ONE OF
THE COLDER ENSEMBLE MEMBERS. PRECIP CHANCES WILL SPREAD ACROSS THE
AREA AHEAD OF UPPER TROF THAT DEVELOPS IN THE WESTERN UNITED
STATES AND MOVES TOWARD THE PLAINS WITH BEST CHANCES CURRENTLY
LOOKING TO BE MONDAY NIGHT INTO WEDNESDAY MORNING.

In English...the group of models they are using aren't in agreement with the cold front positioning and amount of cold air that will dump in. They seem like they will trend down, but not to the levels I pointed out earlier. The new forecast isn't out yet...but they are going for highs in the mid 40s Monday and Tuesday, and around 50 on Wednesday. However, the highlighted text says it all. The spread in the models means they have very little confidence in any of them so we just have to wait.

[Thunder]

This make me sick that Texas get all the snow...

[mugofbeer]

I love these weather threads. I took 9 hours of meteorology in college thinking I wanted to be one before I realized how much math it required. Now I realize how little I know compared to some of you. Keep it up!

[venture]

So after taking time looking at the morning run, the thing is still being stubborn with staying cold. I worked up a couple maps to try to make this easier. Typical disclaimer first...predicting winter storms this far out will normally mean I'll be wrong, but it is fun to try. All this is dependent on the cold air getting in place as some models are expecting. If it doesn't arrive, it'll all be rain or more of a mix. On the maps, the "Mix" area will generally be in locations where the surface temp is near freezing (either just above or below) and where the upper air temps are either just above or below as well. The area will likely fluctuate quite a bit. The amounts for this zone will always be in liquid form. I'm just going with the basic 0.1" liquid to 1" of snow ratio here, but that will probably be off a bit. The mix area doesn't mean ice...the pattern really doesn't look like an ice storm setup. More so rain/snow/sleet mix with some isolated areas of freezing rain.

Through Tuesday Early Afternoon:


Tuesday Evening


Overnight Tues/Early Weds AM


The shading on the 2nd graphic I screwed up, so just pay attention to the values. The very light blue shadding is an area with scattered light snow/flurries - no accumulation expected in those areas. In the last graphic, the snow in SW Oklahoma is going to be closer to an inch accumulation...not so much towards the 3" end.

[venture]

NWS Norman now starting to move into the same line of thinking. Not to really make a point or anything, but just saying. :-P lol

PRECIPITATION ON SUNDAY IS EXPECTED TO BE FAIRLY LIGHT ON SUNDAY
AS THE TROUGH MOVES ACROSS THE AREA. COLD AIR...THOUGH NOT
NECESSARILY EXTREMELY COLD...WILL FILTER INTO THE AREA BEHIND THE
ASSOCIATED SURFACE CYCLONE. EVOLUTION OF A SECOND SHORT WAVE
TROUGH EARLY NEXT WEEK IS SOMEWHAT UNCERTAIN...WITH THE GFS MUCH
FURTHER SOUTH THAN THE ECMWF. THE ECMWF KEEPS THE CWA MOSTLY IN A
DRY SLOT DURING THE DAY ON TUESDAY WITH A STRONG COLD FRONT
EXPECTED TUESDAY NIGHT. THE GFS...ON THE OTHER HAND...FORECASTS
THE SURFACE LOW TO BE MUCH FURTHER SOUTH.

THINKING THAT IT WILL BE DIFFICULT TO ERODE THE COLD AIR FILTERING
IN BEHIND THE SUNDAY FRONT IN SUCH A SHORT TIME...WE WILL SIDE
WITH THE GFS. PRECIP AMOUNTS ARE FORECAST TO BE LIGHT AT THIS
POINT... WITH MOSTLY SNOW EXPECTED ACROSS NORTHERN OKLAHOMA...
MOSTLY RAIN ACROSS THE SOUTHERN PORTION OF THE CWA... AND A
POSSIBLE MIX OF PRECIP TYPES FROM SOUTHWEST INTO CENTRAL OK. WITH
A SIZABLE SPREAD AMONG GFS ENSEMBLE MEMBERS...THIS IS NOT A HIGH
CONFIDENCE FORECAST BY ANY MEANS...BUT THE CONSISTENCY OF THE
DETERMINISTIC GFS HAS BEEN NOTABLE.

[venture]

This evening's run of GFS was a HUGE flip from the previous runs. It has the storm system now moving through Northern OK/Southern KS. Majority of Oklahoma dry slotted similar to the earlier ECMWF. There will be a shot of precip late Tuesday into early Wednesday, but temps are being pushed in the mid 50s now.

Usually when you see a model make this big of a jump, we need to watch it for a couple more runs before adjusting thinking.

[ronronnie1]

Ugh. Wake me up in Spring.

[venture]

Trend continues in taking the low north. I'll probably redo the precip forecast on Sunday after we get a few more shorter term models able to pick up the time period.

[venture]

Models are bringing the system a bit further south into Northern OK this morning, but are dry slotting the entire state now. Ahhhh the joys of trying to predict these things so far out. :-P

[buckt]

Models are bringing the system a bit further south into Northern OK this morning, but are dry slotting the entire state now. Ahhhh the joys of trying to predict these things so far out. :-P

I for one, greatly appreciate the postings you provide! Thanks...

[PennyQuilts]

Me too!

[Thunder]

They need to remove the term "dry slot" and stop mentioning it. I notice when they bring it up, it happens.

[venture]

Urgent - winter weather message
national weather service norman ok
1150 am cst mon dec 7 2009

okz014>026-033>036-080200-
/o.new.koun.ww.y.0006.091208t0300z-091208t1500z/
roger mills-dewey-custer-blaine-kingfisher-logan-payne-beckham-
wa****a-caddo-canadian-oklahoma-lincoln-harmon-greer-kiowa-
jackson-
including the cities of...cheyenne...taloga...weatherford...
Clinton...watonga...kingfisher...guthrie...stillwa ter...
Elk city...sayre...cordell...anadarko...yukon...el reno...
Mustang...oklahoma city...chandler...hollis...mangum...hobart...
Altus
1150 am cst mon dec 7 2009

...winter weather advisory in effect from 9 pm this evening to
9 am cst tuesday...

The national weather service in norman has issued a winter
weather advisory for freezing drizzle and light freezing rain which
is in effect from 9 pm this evening to 9 am cst tuesday.

* timing: Freezing drizzle or light freezing rain may develop by
mid evening but a better opportunity will be overnight into early
tuesday morning.

* main impact: Elevated surfaces such as bridges and overpasses
may develop light accumulations of ice which will cause
hazardous driving conditions.

* other impacts: Some of the precipitation across northern
oklahoma may start as light snow...with light or no snow accumulation.



Precautionary/preparedness actions...

Freezing drizzle and freezing rain rain may cause hazardous driving
conditions. Slow down and be ready for slick spots.