3/7-3/8 Central Plains Storm

[Justin McGinley]

The models and forecast offices have been going numodts about this upcoming storm. The models are still having trouble with the path, but there will be very heavy snowfall with blizzards conditions someone from centeral nebraska to south dakota. So if anyone has anymore info feel free to share!!

 

[Patrick Martin]

Although still pretty far out, GFS is showing surface low setting up somewhere in SE CO as it winds up and then lifts northeast across KS. Projected snowfall totals at this point (for what it's worth) show in excess of a foot from northeast CO/SE WY all the way across NE and portions of SD south of I-90 (at least thru 120hr/12z Wed 3/9). The Denver NWS office is starting to say blizzard conditions could become possible on Tue across the northeast plains if this comes to pass. I for one am pulling for a tick more of a southern track as it would put Denver in the bullseye for a big upslope snow event, and we sure could use the moisture as we are 50% below average snowfall thanks to the La Nina winter.

Still another 48hrs I think before details start to resolve themselves, but appears a healthy snow event is appearing certain for some portions of the plains (and a potential OK chase day) in the Tue/Wed timeframe.

 

[Darren Addy]

Big difference for my area between the GFS 0z and 12z runs. Kearney is in south-central Nebraska and it looked like we would dodge the snow. Local NWS forecast discussion said temps would be too warm for much precip to be even snow around here.

0z GFS for 7 AM on March 9th


12z GFS for 7 AM on March 9th


Apparently the GFS is tracking the low farther SE now, taking it out of CO to the OK panhandle. Local FD mentions that the ECMWF moves the low through a lot faster, which would probably mean less snowfall than the GFS is predicting. GFS also gives our area 20kt+ winds at the time period of the snowfall above, so nowhere near blizzard criteria, but definitely enough to warn of whiteouts.

Will be keeping a close eye on this one, regardless of what my town gets, it looks like this system is going to dump a healthy amount of white stuff in many people's backyards.

 

[jshields]

all the models have trended southeast now. the 18Z GFS being the furthest south and east as it has been on this storm. euro also shifted southeast, cmc and nogaps have been pretty far south for a while. this would put most of nebraska and southern south dakota at risk for easily 6+" snowfall with areas over a foot likely as well. there is going to be a ton of moisture with this storm, as evident by the model forecasts of close to 2" of qpf. i've seen some wfo's say the storm will go south bc of a strong cold front moving through on monday before the main storm kicks out on tuesday. i've also seen talk of the storm path shifting back north bc of the ridge in the southeast and the tendency of the models to show the north shift at the last minute. i want snow, snow, snow here in omaha, so i hope the southerly track of the models the last couple of runs are on to something.

 

[Darren Addy]

0z GFS is out now and the surface low doesn't just track SE, it dives south and basically goes away. Just going by the last 24 hours of GFS model runs, my area has gone from a trace of snow, to 12", to 6" from this coming system. Interestingly, the 700mb closed low remains and tracks from SE Colorado/NE New Mexico to western Missouri in 18 hours.

 

[jshields]

models have continued southward trend and are also showing somewhat weaker with most keeping the low above 1000 mb. winds won't be as strong then and the system seems to move a little quicker. gfs is still putting out 6-12" amounts over northern kansas into nebraska and iowa, and then heavier amounts in southern wisconsin. the 12Z NAM is now out to 0Z Wednesday and it shows a much stronger wave coming out on monday ahead of the main storm that drops at least 6" across most of nebraska. then the second wave comes through and has more snow on tuesday afternoon on. it still shows very heavy snow in central/eastern nebraska at 0Z Wednesday when the model ends. This leads to 15+" of snow already in Nebraska and the snow isn't done yet when the model ends. I'm sure this is an extreme amount and is partially dependent on the monday wave that not a lot of wfo's are going crazy about, but the NAM has been actually somewhat close to actual final amounts this winter, even though they did seem extreme at the time of the model forecast.

 

[jshields]

here's the 18Z NAM. the NAM has been consistent with showing the stronger wave on monday with .75-1" of qpf on mondays storm alone. then it shows that amount again for tuesday's storm. the nws wfo's at this time are only saying 1-3" for monday's storm

 

[Chris Carter]

From what i can see from the NAM, at least for the south east Nebraska area is snow for the first round, then a rain snow mix in the beginning of the second round finishing off with snow. While the heavy amounts stay to the west and north of the area. Seems like a pivot area from North Central Kansas to Northeast Nebraska. Haven't seen temps play such a crucial role in a moisture storm like this all year. It will be interesting to see how this plays out.

While i do like the QPF from the NAM, I like the placement of the rain/snow line on the GFS, far enough south that it keeps snow for all Nebraska, GFS has been remarkably consistent in that aspect of the forecast, while its been a bit wavy on QPF placement and amounts. Have to give the NAM more time to know whether its having trouble with placing the R/S line or if the GFS is too far south.

 

[Darren Addy]

Maybe (probably) I'm not seeing it right, but I don't get the differences between the precipitable water that the NAM is showing and the QPF that the HPC is showing for the same time period. Just doesn't look like enough moisture to produce the big totals. The GFS seems to draw a map closer to the snowfall amounts that the NAM's precipitable water is showing, assuming around a 16:1 ratio.

The NAM seems to have the whole show covered inside its 84 hr window for Nebraska, but for points farther east the show isn't over when you reach the last frame of the NAM's predictions.

 

[Jonathan Whitehead]

Well the southward trend in the models has been pretty well covered by many of the preceding posts so want go to much in detail about that. As far as how this all shapes up in terms of amounts, it appears that 40-50 miles either side of a line from Goodland, KS to Hastings, NE and points EWRD toward Omaha will see the greatest amount of snowfall when all is said and done. What models are showing now that they werent showing 2 or 3 days ago is a lead wave approaching Monday morning that will initiate snowfall across NWRN KS into WRN NE. This will pretty much exacerbate snowfall totals on top of Tuesdays system. GFS was the first to shows this yesterday but wasnt until today that several other models including the NAM have jumped on board with this feature/scenario. As Monday's system lifts out, there may be a lull in snowfall overnight Monday due to s/wv subsidence. Not 100% positive on this but will have to be watched. The bigger show will be on Tuesday as the sfc low across the Panhandles begins to eject out across the Central Plains into NRN MO thru the day. As it does so, isobaric gradients will increase and we should see stronger surface winds as a result across NRN KS into SRN NE leading to near whiteout conditions. LSERs will be on the high end with Tuesdays system...approaching 12 to 1...with the SREF showing possible 2"/hr snowfall rates across the aforementioned areas. When all is said and done, would not be surprised to see a foot more from GLD to OMX. Of course Tuesdays system is still well off the CA coast so subtle shifts in the track of the sfc low are possible but due to the amount of agreement in the numerical models at this point, I think the said snowfall totals are on the high end of the confidence meter wrt to geographical location.

 

[Darren Addy]

Chris' analysis seems to be backed up by this evening's forecast discussion out of Hastings (GID) which is more explanatory than ususal. Relevant stuff:

MOVING ON TO TUESDAY...WHAT IS ALMOST A CERTAINTY IS THAT A MAJOR
STORM SYSTEM WILL MOVE ACROSS THE PLAINS. HOWEVER THE EXACT TRACK
OF THIS SYSTEM IS STILL A BIT UNCERTAIN. MOST OF THE MODELS WERE IN
FAIR AGREEMENT WITH THE TRACK OF THE MID LEVEL LOW PRESSURE
SYSTEM...CONTINUING MORE OF A SOUTHERN TRACK THAN WHAT WE WERE
SEEING A FEW DAYS AGO. HOWEVER THE 12Z EC MODEL CONTINUES TO BE THE
OUTLIER WHICH IS A CONCERN CONSIDERING HOW WELL IT OFTEN PERFORMS IN
THESE WINTER TIME SCENARIOS. TO POINT OUT THE DIFFERENCE...WHEN
CHECKING THE POSITION OF THE 700 MB LOW BY 00Z WED...THE EC
POSITIONS IT A LITTLE WAYS NORTHWEST OF BEATRICE... WHILE THE NAM
AND GFS ARE ABOUT 150 MILES SSW OF THERE IN KANSAS. THE GEM IS IN
BETTER AGREEMENT WITH THE NAM AND GFS AND THE LATEST SREF ALSO LOOKS
TO BE IN LINE WITH THE SOUTHERN SOLUTION. ALL THE MODELS SHOWING
IMPRESSIVE FORCING AND MOISTURE WITH THIS SYSTEM AS NOTED IN THE
TIME HEIGHT OMEGA PLOTS. BOTTOM LINE HERE IS NO MATTER WHICH TRACK
ENDS UP BEING RIGHT...SYSTEM WILL BE SO INTENSE THAT SOME OR ALL OF
OUR CWA SHOULD GET QUITE A BIT OF SNOW. INITIAL SNOW TOTAL GRIDS
WILL RANGE FROM 8 INCHES IN OUR NW TO AROUND 12 IN THE SE WITH SOME
TWEAKING EXPECTED AS SYSTEM APPROACHES. THIS INCLUDES MONDAY SNOW. . . .AT THIS TIME WILL GO WITH SLIGHTLY HIGHER SNOW AMOUNTS IN THE SE
PART OF OUR CWA ALTHOUGH MOST OF OUR AREA COULD BE UNDER THE GUN FOR
HEAVY SNOW. AS NOTED ABOVE...MONDAY WILL SEE THE OPENING VOLLEY WITH
THE REAL ACTION SLATED FOR TUESDAY AND TUESDAY NIGHT.

The part about the EC being the outlier, and yet the best performer in these sorts of systems is an interesting bit of info.
I've noticed that the GID FDs lean heavily on the models, while LBF is a little more "old school". They are less wordy, but sometimes point out deficiencies in the models and they seem to refer more to actual soundings. Their latest is an example:

ISENTROPIC UPGLIDE BECOMES ESTABLISHED IN
WESTERN NEBRASKA WITH THE FIRST MAJOR PUSH OF THE DOUBLE-SHOT STORM
SYSTEM. WITH COLDER AIR IN PLACE...PRECIPITATION MOST LIKELY BE SNOW
FROM THE START. FORECAST SOUNDINGS INDICATE A SATURATED NEARLY
ISOTHERMAL LAYER FROM 4000-9000 FEET MSL. THE TEMPERATURE IN THAT
LAYER IS EXPECTED TO BE -5C TO -10C WHICH IS COMPATIBLE WITH A SNOW
TO LIQUID RATIO OF 12 TO 1. SNOWFALL TOTALS ALONG AND NORTH OF U.S.
HIGHWAY 20 WILL BE 4-6 INCHES WITH 1-2 INCHES ALONG THE INTERSTATE
80 CORRIDOR. THERE IS POTENTIAL FOR LOCALIZED ENHANCEMENT WITH
NEGATIVE EQUIVALENT POTENTIAL VORTICITY (SLANTWISE INSTABILITY)
INDICATED IN PARTS OF NORTH CENTRAL AND NORTHWEST NEBRASKA.

.MEDIUM RANGE AND EXTENDED...MONDAY NIGHT THROUGH SATURDAY.
AS THE SNOW IS WINDING DOWN MONDAY...ISENTROPIC UPGLIDE DEVELOPS
AGAIN IN THE 285-300K LAYER WITH A CONNECTION TO THE TEXAS GULF
COAST. THE LIFT WILL BE DEEPER THAN THE PREVIOUS SYSTEM WITH BETTER
MOISTURE. AT THIS TIME...IT APPEARS THAT THE SECOND SHOT WILL
PRODUCE SIGNIFICANTLY MORE PRECIPITATION THAN THE FIRST PUSH. LOW
LEVEL TEMPERATURE PROFILES STILL LOOK COMPATIBLE FOR A 12 TO 1 SNOW
TO LIQUID RATIO. IT APPEARS THAT THE SECOND PULSE WILL PRODUCE MORE
WIDESPREAD SNOWFALL WITH THE HEAVIEST IN SOUTH CENTRAL AND SOUTHWEST
NEBRASKA. AMOUNTS OF 6-9 INCHES ARE POSSIBLE ALONG AND SOUTH OF
INTERSTATE HIGHWAY 80 WITH 3-6 INCHES POSSIBLE OVER CENTRAL...NORTH
CENTRAL AND NORTHWEST NEBRASKA.

 

[jshields]

new 0Z models are out and the Euro looks like it is nearly identical to the GFS and having the low swing south into OK/ Northern TX before ejecting it northeast through Missouri. this would keep almost all of the precip as snow in Nebraska and northern KS and points on northeast of there. another model run down and the dreaded north shift hasn't taken place yet..... also still looks favorable for a general 3-5" of snow on monday as well. i'm hoping any snow on Monday with the first wave will keep down temps just a couple of degrees on Tuesday, which is going to be a critical amount. also looking at the forecast models, they have a strong northeast wind most of the day on tuesday which i think will make it even more difficult to get much warming. especially with precip falling most of the day. here's a neat site that some of you are probably already aware of, that breaks down temp, winds, and precip amounts by hour according to bufkit:

http://www.meteor.iastate.edu/~ckarsten/bufkit/image_loader.phtml?site=oax&ratio=11&compaction=0

this is for omaha, but in the upper left hand corner you can change locations

 

[RMacDonald]

Update: Looking at some potential for some good snowfall potential for the Nebraska and Kansas areas, right now I am seeing, based on my model snowfall accumulation of between 9-14" of total snowfall. Central Kansas on the high side of that. Seeing rates approaching 1" per hour for about a 5-7 hour block across this region. Here is the latest 8-9Mar Snow Potential zoomed into the NE-KS regions.
http://smartwxmodel.net/snow.pdf

 

[Chris Carter]

Well the models have taken that dreaded northern track, however its been consistent. Heavy snow seems to stay out west and north of that Lincoln to Omaha line, in fact it sounds like most of southeastern Nebraska will see a rain/snow mix Monday night changing to all rain Tuesday before going back to a rain/snow mix Tuesday night. Here's hoping that the models go back to more southward track, but I remain optimistic since I just got my car washed in Omaha.

 

[RMacDonald]

Yeah starting to see a gradual shift of the heaviest snowfall, updated the graphic above., still showing NC Kansas into S. Nebraska. Still showing some potential of 10" of snow across this area. As for the Omaha and Lincoln areas, it is still wanting to keep the snow in, though it has lowered the actual accumulations a bit and the forecasted surface temperatures are a bit higher now. Will need to keep a close watch on this.