1/19/07-1/21/07 FCST: NM / TX / OK / KS / AR / MO / NE / IA / IL / ETC(WINTER PRECIP)

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Models coming into better concencus for the next potentially significant storm to bear across the United States. This thread is to organize discussion on this event, with models just beginning to organize widespread winter precipitation, early indications showing a *potential* snow event for the Texas Panhandle, Oklahoma, Kansas,Iowa, and Missouri, with lighter snows north and west. This far out of course, no one knows for sure as the last system was quick to point out. Let's begin winter weather forecasting for this next system. Way too early for a first call on this by any means. What we know for sure is: a system is approaching. Will it dig farther and slow down? Models tend to race it a bit much. If it can slow and dig, I think the chances for a sig storm will be greater, and also farther north and west then currently indicated. As with the last system, I do not think moisture will be a problem. I do believe that this may impact the same areas as the last storm in my opinion, but again, *way* too early yet to tell. Let the fun forecasting on this next winter storm begin!
 
Not to focus specifically on one particular model at this point in the game (I know, ensembles, ensembles), but GFS on the new 00z run at the 108 (!) is showing some impressive QPF in the way of ice and snow, especially for Eastern Oklahoma. Tulsa especially should begin to pay attention to the forecasts...*if* this pans out this could be pretty impressive. GFS is showing a stronger and more dynamic storm with this run.

Of course, there will almost certainly be plenty of run to run changes the next few days. Just pointing out that I am expecting this to be a fairly significant storm for some portion of the plains to say the least. Considering how GFS was underestimating the precipitation on the last storm and ETA really blew it up, to see GFS with copious QPF is pretty interesting in my opinion. Watching the model runs change day to day is a lot of the fun of watching the evolution of winter storms. Let's just hope the models initialize better in the pacific than the last storm and come to an agreement earlier than last time (when it was practically on top of our heads before everything came together, and in a way that threw practically all forecasters for a loop and a headspin).
 
Winter Storn Watches

Lubbock has gone ahead with Winter Storm Watches for the potential of a major winter storm event, predicting a greater of 6" or more for the Texas Panhandle.

To emphasize the rarity of this event, I want to post this blurb from the Lubbock NWS AFD:

GFS MODEL SOUNDINGS INDICATE A RARE TOTAL SATURATION THROUGH THE
COLUMN AT LBB WITH PERIODS OF SIGNIFICANT LIFT IN THE DENDRITIC
SNOW GROWTH ZONE. THIS WOULD EQUATE TO PERIODS OF HEAVY SNOW AND
MORE INTENSE ACCUMULATIONS IN SPOTS. IT SHOULD BE NOTED THAT WARM
AIR ADVECTION MAY INCREASE ENOUGH OVER THE SOUTHERN SOUTH PLAINS
AND SOUTHEAST ROLLING PLAINS TO PROVIDE A BRIEF WINDOW OF SN/IP
BUT GIVEN THE COLD AIR AND AMOUNT OF LIFT WE WILL KEEP P-TYPE ALL
SNOW. IN COORDINATION WITH HPC...THERE IS AN ABOVE NORMAL
CONFIDENCE FOR 6 INCH+ SNOW AMOUNTS WITH UP TO 1 FOOT POSSIBLE IN
SPOTS.

How rare this is has yet to be seen as it is rare for a WSW to be issued greater than 36 hours...but according to Lubbock there is a potential for greater than a foot of snow. This could be a very, very interesting storm for the Texas Panhandle to say the least.

Now the forecast mode for this: dont see many changes or disagree with the reasoning of Lubbock. NAM and GFS are in consistency and we see a lot of moisture with this and what will probably turn out to be a major storm for a lot of the plains once again. Still thinking Tulsa area will really see the brunt of this as well as of right now. I have noticed that the NWS has increased POPS from Lubbock to Tulsa to likely...which is showing remarkably high confidence. As far as the track goes, I still would not be surprised to see this shift farther NW, but not going there at this time as this is still a ways out.
 
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One thing making me skeptical with this, at least for central Oklahoma, is the lack of a strong arctic high building in from Canada or the Northern Plains during the storm. This is my second winter here in Norman and that's something that's been present with every bout of wintry precipitation so far. I'm clueless when it comes to making connections between synoptic features at different locations and different levels of the atmopshere, so I might be missing something.

Overall, the cold air just seems marginal as shown by the models ATTM and given the long-running tendency for sleet in this area, as well as 1000-500 mb thicknesses of > 546 dm shown on the GFS and NAM, I'm fully expecting precipitation type to be an issue. However, my additional concern for this event would be that even surface temperatures could be marginal in the absence of a new push of arctic air.
 
One thing making me skeptical with this, at least for central Oklahoma, is the lack of a strong arctic high building in from Canada or the Northern Plains during the storm. This is my second winter here in Norman and that's something that's been present with every bout of wintry precipitation so far. I'm clueless when it comes to making connections between synoptic features at different locations and different levels of the atmopshere, so I might be missing something.

Overall, the cold air just seems marginal as shown by the models ATTM and given the long-running tendency for sleet in this area, as well as 1000-500 mb thicknesses of > 546 dm shown on the GFS and NAM, I'm fully expecting precipitation type to be an issue. However, my additional concern for this event would be that even surface temperatures could be marginal in the absence of a new push of arctic air.

Yes, it might be marginal in the sense of differentiation of sleet/snow, but not for frozen/liquid, from what I can tell. I really don't think the surface temperatures will be an issue. Sure, we will actually be having southerly surface winds this weekend, but the trajectory of these winds will be over ground to the south of us that has also had accumulating sleet/snow/ice over the last couple of days. Consider also that the source region for these winds is not the Gulf, but rather recirculated, modified arctic air around a high pressure system to the east. Thus I'm a little skeptical of the model surface temperature forecasts this weekend. Given the frozen precip cover over a large area, I suspect that the forecasted temperatures are a bit on the warm side.
 
Update and New runs

Oklahoma City has put the entire Forecast Area under a winter Storm Watch.

GFS is very consistent with the run with the path remaining right on target. Of interest is the 84 ETA which pulls it sharply to the northwest, and has more intense QPF. If ETA is to be believed, moderate to heavy snow (in the area of .50 to .75 LIQUID QPF in a 6 hr period!!) falls in a SW Oklahoma Bullseye. a very impressive run with lots of moisture to say the least - if we follow ETA. For now, am going to rely on the GFS - however with the last system, the ETA was more accurate with storm track and the GFS caught on way too late. NWS estimates 4 to 8 inches of snow for OK but I am thinking more in the area of 5 to 10... *if* the system does not pull more to the northwest like many of these types of systems tend to do. The fact ETA pulls it NW is worrisome to the track...but certainly pulls in the moisture and dynamics look very favorable for a major winter storm.

Synopsis on this run: GFS farther SE and weaker than the ETA shows, but consistent in its output... ETA pulls it NW and has it going gangbusters with QPF. Absolutely believe the winter storm watches are more than warranted, and also believe models will intensify this event more. Am actually leaning toward ETA for path - the last storm track had it way too far south due to poor pacific initialization. Wondering if this is a repeat.
 
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Change

ETA...wow...getting closer and does this look familiar. ETA at the 84....all I have to do is ask you to look at the 84 ETA. (Graphic was taken out.)



What more needs to be said. Except this is a farther NW (again) and stronger scenario and now paints a winter storm over a LARGE part of the plains, now even into Nebraska and Iowa. Talk about a lot of snow and QPF. GFS is also nudging (slowly) more NW each run.

What needs to be said now is with the ETA on the scope, a LOT more of the plains needs to watch now and prepare for a possible winter storm... and the southern plains may...may miss out on this. Keep in mind GFS is maintaining the southern path. However, like last system, GFS maintained the south path and ETA was more dead on with the path. Based on that, I am going to side with ETA and push this system more NW and forecast more snow for at least Kansas and Missouri...at least. I need to see more runs before I really get sold on this. I am also keeping in mind for these sort of systems to frequently push more NW as the event gets closer.
 
Lubbock NWS was sending out press releases on this event TWO DAYS ago, so they evidently DO have "above normal confidence". Some of the forecast snowfall totals for our area are amazing. The last snowfall that even came close in the Lubbock area was in 2000. I personally don't remember a time with 12" of snow, although I am sure it has happened. I am actually quite excited about this!
 
And for good reason, David, as Lubbock city itself sits under a heavy snow warning with winter storm warnings farther east. In fact, check out the predicted snow totals issued by the National Weather Service... this is amazing.


TOTAL SNOWFALL ACCUMULATIONS OF 7 TO 13 INCHES ARE EXPECTED ALONG
AND WEST OF A BROWNFIELD TO LUBBOCK TO FLOYDADA TO SILVERTON
LINE. ACCUMULATIONS OF 8 TO 15 INCHES WITH ISOLATED AMOUNTS UP TO
18 INCHES ARE EXPECTED OVER THE REMAINDER OF THE EXTREME SOUTHWEST
PANHANDLE AND NORTHWEST SOUTH PLAINS.

To the east and southeast Winter Storm Warnings due to a wintery mix of precipitation including ice accumulations. Where it's all snow, the snow will certainly be heavy as models continue to agree on an open slug of moisture bullseye-ing Lubbock area, it seems.

I am not sure when the last time 18" of snow was predicted for the Texas Panhandle... but this would undoubtably make it one of the most significant winter storms for this portion of the country. Quick check of the models maintains the path of the storm so yes, good reason for the "above normal confidence".

As for the rest of the central plains, the big issue is speed. The system is progged to really move so snow, even moderate to occasionally heavy, appears to be quick to leave so this will likely temper accumulations - but we'll wait and see. What the big focus is is with this is indeed the Southern Plains and what could be an incredible amount of snow.
 
The State of Texas SOC has issued a situation report which contains a capsulized version of what is forecast during this event for the entire state. You guys might find it interesting.
http://www.txdps.state.tx.us/dem/sitrepindex.htm

Lubbock and surrounding towns are currently preparing for what looks to be the most significant winter even in probably the last 25 years for our area with as much as 18" of snow forecast for parts of the areas. I know you folks further north would probably laugh at this, but it's a rare enough event for this area that most of the general public is NOT going to be prepared for it. Additionally, power outages are expected due to the increased strain on the power grid. There will be a significant amount of vehicle accidents and injuries, possibly even deaths during this event. Drivers in this area are very inexperienced with this sort of weather, despite the warnings days ahead of time.

I just got back from a trip to the grocery store and Walmart. It looked like the day after Thanksgiving. Items sold out include any form of bottled water, lamp oil, coleman stove fuels, firewood - both real and fake, sidewalk salt and blankets. Various canned goods were declining fast.

I myself am expecting to leave home tomorrow sometime and probably not return until sometime Sunday or Monday. In addition to being out reporting for the local NBC station, my partner and I will possibly be participating with the local ARES group in various ways since he has a 4x4.
 
Not quite as bad David but close to your situation here in Amarillo. Grocery stores are packed and my Emergency Service Unit has been alerted for a very busy weekend. Luckily I just had my new transmission installed this week and my 4 wheel drive works again also.

Amarillo NWS is calling for anywhere from 4-8 in most areas with some local reports of 10-12 south of I-40. Most models dont start precip until after 21z for amarillo with the heaviest during the overnight hours into midday saturday. One trend I have noticed is the last few runs have slowed the progression of the system so snow may last until sunday morning.

I expect the worst hit area to be west of I-27 between Lubbock, clovis and Amarillo along and south of hwy 60 with local reports of 12-18". QPF was 1.2"-1.5" with at least a 10/1 conversion ratio. some areas may be 15/1 but models cant make up their mind on exact ratios yet.

Will be a great Sunday to stay in and watch some football except I have to work for part of it and I am sure I will be out working wrecks the rest of the time.
 
Absolutely impossible to tell what's going to happen in Central Oklahoma if you forecast using a model consensus...WRF/NAM show rain or rain/snow mix thermodynamic profile with strong isentropic ascent on saturday into sunday. GFS shows a heavy snow thermodynamic profile. Winter storm warning was issued because the public has been impacted by severe winter weather frequently and recently here in OKC...so NWS isn't taking any chances in case the worst happens. Heavy precipitation looks likely but the type of precip will be extremely variable and may change several times at any given location here in C OK. Should be a band of heavy snow on NW side of surface low due to strong WAA and CSI over cold surface temps.
 
This system looking better and better with every run.. Also important to note an H8 trough that could shear the system and allow for a couple more hours of heavy snow.. Which could really bump up the totals. Lots of watches must equal lots of confidence this far out.. Moisture, and the H8 trough will play key in the next 12-24 hours
 
This storm could break Lubbock's all-time snow records:

Maximum Snowfall in 24 hours: 16.3" January 20-21, 1983
Maximum Snowfall from a single storm: 16.9" January 20-21, 1983

Take a look at the days this record was set....kind of ironic eh??? ;)
 
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Winter WX to affect Eastern IA Sunday...

A winter storm will affect the eastern Iowa area starting early Sunday morning. Cedar Rapids: Snowfall will start at 7 AM Sunday and taper to flurries by 5 PM after accumulating to 4 inches of new snow. Iowa City: Snowfall will start at 6 AM Sunday and taper to flurries by 4 PM after accumulating to 5 inches of new snow. Discussion: Vort. max. associated with upper-low over the Baja area will slowly eject towards the Midwest over the next two days as height falls move into the Pacific Northwest and then towards the Upper-Midwest through the period. The vort. Will then transition through the developing large-scale trough over the western half of the CONUS. After 06Z Sunday, dynamical fields will increase dramatically over the southwest half of IA with good omega in the dendritic layer over southeastern IA. Temperatures will be well below freezing through all layers of the atmosphere and thermal profiles indicate snow ratios between 12-1 and 16-1. Current indications suggest best forcing will last less then eight hours while dry-slotting moves in from the southwest late in the period. It is possible that a deformation zone may develop along and just south of I-80 in eastern IA, which may may lead to locally higher precipitation totals. Overall model agreement (NAM-WRF, GFS, and UKMET) has been favorable over the last three runs while being consistent with the features of this system. - bill
 
Observed 00z soundings at OUN and AMA are a little warmer around 750 mb than corresponding NAM 0-h soundings at 00z. Early observations from SW OK/NW TX reveal quite a few locations with rain/freezing rain and not snow, thus the warm nose appears to be a problem. I have doubts that temperature profiles will cool much given that were nearing saturation already, so the snow totals could be a bit less than expected along the I-44 corridor in OK. The best hope for accumulating snow will be cooling the warm nose through melting with relatively high precip rates, and cold ground acting to slow melting at the surface.

Rich T.
 
Dodge City's first 1" snow event!

Wow, I'm starting to really like the looks of the track of the 500mb vort and the shift from a neutrally tilted system to negatively tilted...for me here in Dodge City...essentially allowing the development of a nice "trowal" airstream north of the cyclone path... This could be a surprise little snowstorm for here in Dodge... every model run has come in with more QPF... there could be heavy snowfall rates late tomorrow into tomorrow evening... there may be an 8-10" hit farther northwest than the models indicate of this mid level cyclone matures and occludes the way the 00z/20 NAM and GFS indicate.. I'll be blogging a few posts on this one on my website (http://www.underthemeso.com/blog)

Mike U
 
I am still sticking with my 12"+ for Amarillo. We finally transitioned over to all snow about 830pm CDT with a pretty heavy band that moved through dumping dollar sized flakes that quickly covered the roads and grass. Small break right now but another large area moving in from Hereford in the next hour or so. We ended up with less than a 1/4" of ice and sleet before the snow started. Now i dont see the snow ending until late saturday night with QPF of still between 1"-1.5" and the warm layer eroded it should stack up well. Much better than ice!!

To see Amarillo roads live here is a link to TxDots highway webcams around amarillo
http://amaits.dot.state.tx.us/its-cameras/?Speed=High
 
This winter event in central OK is a classic example of the the weaknesses of deterministic (yes/no) versus probabilistic forecasts. Discussions with other meteorologists back on Wed-Thu revealed a wide range of possibilities for precip type, and we loosely assigned probabilities to each type. Given the marginal temperature profiles and simple climatology, we came up with chances for just about anything, and nothing in particular came close to dominating the probabilities.

The variation in precip types at my house this morning has underscored that uncertainty. We've experienced a mix of rain, freezing rain and sleet, though ice accumulations have been almost trivial because surface temperatures are right at 32 F. I suspect Norman will end up with no significant impacts from this storm, except for tough driving conditions where it rains on remaining ice patches. Meanwhile, the OKC metro area has been bracing for 5-10" of snow as if it were a near certainty...

Rich T.
 
I've also experienced a mix of rain/freezing rain at my apartment in SE Norman, and the temperature has risen to just above freezing. There is a light ice glaze on bushes and trees, but nowhere else. The 12Z OUN sounding showed a small warm layer straddling 800 mb of about 2 degrees Celsius max. If we don't get a changeover to snow soon, our snowfall potential here in Norman is in real jeopardy. I'm thinking as some of the heavier precipitation moves in, we might be able to cool that warm layer off enough through lift and melting to changeover. This is seriously about as close to the edge as you can get as far as rain/snow differentiation is concerned! We will see...
 
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