Bryan_Knitter
EF1
Pardon my ignorance, but do you have a link to where you are seeing these models?
-
While Stormtrack has discontinued its hosting of SpotterNetwork support on the forums, keep in mind that support for SpotterNetwork issues is available by emailing [email protected].
12/11-12/13 FCST Midwest
- Thread starter Ryan Wichman
- Start date
Jesse Risley
Staff member
Well, even the HPC's model diagnostic discussion leaves room for plenty of guesswork, but absent what they have noted (partial copy below), the dubiety is quite evident even by taking just a passing glance at only the GFS, ECMWF and the NAM runs between 12z yesterday, 00z today and 12z today. Some of the model fluctuations are being attributed to latent heat release.
The system hasn't yet developed and subsequently been sampled by the upper air observation network, and data probably won't be ingested by the RAOB network until late tomorrow afternoon, at the earliest. As a result, I'm sure the 00z runs tonight, along with tomorrow's 12z runs, will continue to show potentially rabid aberrations in the final outputs.
Looking for models? I may not have the kind you want to see
, but many of them can be found HERE.
Last edited by a moderator:
Robert Dewey
EF5
As of right now, my initial track looks a bit too far S. The GEM hasn't been too consistent either... with the 0z keeping the system much weaker and further SE (in line with the 0z ECMWF, which took an inconsistent jump), and the 12z showing a stronger / further NW solution... and then there's the NAM; a deeper but more diffuse-looking surface low that is MUCH further NW.
The only thing I can really say about this system for the southern Great Lakes is that 1) if will most likely precipitate (ptype and amount are an issue), and 2) it will get cold and windy behind the system as high pressure builds in.
I'll update the track and go with Belleville, IL up towards Cleveland, OH and Buffalo, NY.
The only thing I can really say about this system for the southern Great Lakes is that 1) if will most likely precipitate (ptype and amount are an issue), and 2) it will get cold and windy behind the system as high pressure builds in.
I'll update the track and go with Belleville, IL up towards Cleveland, OH and Buffalo, NY.
Robert Dewey
EF5
12z ECMWF is back to being further NW, sort of like the GEM. 18z NAM is still "different." Can't wait until the energy comes ashore so it's better sampled... most likely tomorrow evening's 0z run.
Jesse Risley
Staff member
The Davenport, Iowa forecast office inserted an interesting diatribe about the model aberrations and corresponding latent heat driven changes in their afternoon AFD today:
All in all, I think that forecaster does a fairly decent job of describing, in his opinion, why the model runs have had such large oscillations from one run to another in respect to the placement of the surface low, particularly this close to the event and within a 24-hour time frame..
All in all, I think that forecaster does a fairly decent job of describing, in his opinion, why the model runs have had such large oscillations from one run to another in respect to the placement of the surface low, particularly this close to the event and within a 24-hour time frame..
Robert Dewey
EF5
NW trend continues on the latest NAM and GFS. Looks like my original track(s) may have busted big time. Looks like a light to moderate rain/snow mix for southern MI at this point.
Robert Dewey
EF5
Looks like the NAM and GFS have trended slightly south, with the 500mb trough and associated energy digging in a bit deeper out further W, which translates into a more southerly system. Just winging it, I would say the surface low is about 50-75 miles further SW (NAM-GFS respectively) of the 0z forecast, valid at 0z 12/12.
Here's some differences between between the previous NAM and the current NAM:
200mb heights:
500mb heights:
1000-500mb thickness:
Red indicates areas where heights were higher on the previous run (60-70m higher at 500mb), blue indicates heights that were lower... and transparent / black indicates little change.
EDIT: Looks like the operational 12z NAM is one of the farthest north solutions out of the various WRF runs: http://www.emc.ncep.noaa.gov/gmb/tp...rack.srperts.2010121009.east_coast.single.gif
Here's some differences between between the previous NAM and the current NAM:
200mb heights:
500mb heights:
1000-500mb thickness:
Red indicates areas where heights were higher on the previous run (60-70m higher at 500mb), blue indicates heights that were lower... and transparent / black indicates little change.
EDIT: Looks like the operational 12z NAM is one of the farthest north solutions out of the various WRF runs: http://www.emc.ncep.noaa.gov/gmb/tp...rack.srperts.2010121009.east_coast.single.gif
Last edited by a moderator:
Bryan_Knitter
EF1
Correct me if I'm wrong, but from what I gather from this, the further south this tracks, the higher snow totals for my area (SE WI), correct??
Ben Kossow
EF0
Probably, as we'd receive more snow and less of a mix or rain (I'm in the same area). I'm guessing locations right along the lake will probably receive a little less snow too since the waters are relatively warmer. But much depends on where the low tracks.
Robert Dewey
EF5
Here's a model forecast for you guys - 12z WRF based on the GFS: http://wrf-model.org/plots/realtime_main.php
It usually has an extreme bias when it comes to system strength, but still fun to look at. It did, however, nail the <955MB low that exploded over the midwest earlier this fall though. Don't count on it verifying.
EDIT: Looks like other ARW (Advanced Research WRF) are exhibiting a similar bias (and usually do). I wonder what causes that..
It usually has an extreme bias when it comes to system strength, but still fun to look at. It did, however, nail the <955MB low that exploded over the midwest earlier this fall though. Don't count on it verifying.
EDIT: Looks like other ARW (Advanced Research WRF) are exhibiting a similar bias (and usually do). I wonder what causes that..
Last edited by a moderator:
Robert Dewey
EF5
After looking at the NCEP track ensembles & the operational model trends, I'm going to go with a track right along the MI border; this is pretty much in the middle of the NCEP ensemble envelope - http://www.emc.ncep.noaa.gov/gmb/tp...rack.aeperts.2010121012.east_coast.single.gif
UPDATE: Looks like the 12/10 12z ECMWF is also on board with a southern track once again... even a bit further south than the GFS. 18z NAM also trending that way. Thermal profiles are tricky across the Metro Detroit area, riding just to the right of the 0C isotherm in the sfc-800mb level on both the GFS/Euro, cooling only slightly below 0C when precipitation starts. The system is taking quite a unique track, and I suspect wherever the precipitation pivot point sets up will get quite a bit of QPF.
UPDATE: Looks like the 12/10 12z ECMWF is also on board with a southern track once again... even a bit further south than the GFS. 18z NAM also trending that way. Thermal profiles are tricky across the Metro Detroit area, riding just to the right of the 0C isotherm in the sfc-800mb level on both the GFS/Euro, cooling only slightly below 0C when precipitation starts. The system is taking quite a unique track, and I suspect wherever the precipitation pivot point sets up will get quite a bit of QPF.
Last edited by a moderator:
Bryan_Knitter
EF1
Looks like the current track predicted by NWS MKE will start us off with rain here, changing to all snow Saturday afternoon. Then the winds pickup out of the North 20-30mph.
I'm still hoping for a more Southerly track though. Much rather get all snow vs rain/snow mix.
I'm still hoping for a more Southerly track though. Much rather get all snow vs rain/snow mix.
Robert Dewey
EF5
The 15z SREF came in, and about 90% of all the WRF runs are further south than the 18z NAM. Also notable is the lack of coastal development. I wouldn't be surprised to see a track from Davenport IA to Akron OH before turning NE up into Ontario, Canada. 18z GFS also looks like it's further south than its 12z run.
Here's my track forecast. Red was my initial track from a few days ago, blue is the most recent.
Here's my track forecast. Red was my initial track from a few days ago, blue is the most recent.
Last edited by a moderator:
Bill Schintler
EF4
Central and Eastern Iowa
A powerful winter storm will affect the upper-Midwest starting Saturday. The worst conditions will pass to our north, with more then a foot of snow with strong winds expected in the Twin Cities area. Here in eastern Iowa, precipitation will start after midnight as rain. A strong cold front will reach the Cedar Rapids and Iowa City area by late morning, with precipitation changing over to snow between 1 and 2 PM. Winds will increase out of the northwest during the afternoon, with gusts increasing to 50-60 mph or more by evening! Even with only a few inches of “powdery†snow, travel in rural areas will become difficult in much of eastern Iowa. Below is time of arrival and total snow accumulation for tonight’s event for specific locations in central and eastern IA:
Cedar Rapids, IA (Eastern IA Airport):
Rain will start at 1 AM tonight, and change to snow after 1 PM Saturday. Total snowfall: 3.5 inches.
Iowa City, IA:
Rain will start at 1 AM tonight, and change to snow after 1 PM Saturday. Total snowfall: 3.2 inches.
North Linn Co., IA (Paris and Coggon):
Rain will start at 1 AM tonight, and change to snow after 1 PM Saturday. Total snowfall: 3.8 inches.
Marengo, IA:
Rain will start shortly after midnight, and change to snow after 12 PM Saturday. Total snowfall: 3.4 inches.
Union, IA:
Rain will start at 11 PM, and change to snow after 11 AM Saturday. Total snowfall: 4.0 inches.
Discussion:
Forecast confidence remains low with snowpack-enhanced baroclinic zone over the area. Forecast models still differ considerably as to the track and evolution of the surface and 850mb lows. The UKMET is indicating a southerly bias with the low track, while the NAM and GFS continue to favor a more northerly solution.
Tonight, strong warm air advection ensues with precipitation breaking out as rain in most areas of eastern IA. A mixture of freezing rain and rain is likely along and north of US-20 where a deep snowpack is in place and surface temperatures are lower. Surface cyclogenesis will occur in Iowa Saturday along a strong baroclinic zone as a 145kt 300mb jet streak and a series of embedded shortwaves approach the area. The track will then follow the upper-dynamics, of which inconsistencies exist. Looking at 12Z upper-air data and satellite imagery, it appears as though the jet streak which will evolve into an upper-low is verifying stronger then most models indicate. It is possible that the upper-dynamics and surface system will follow a more southerly track, which would result in heavier snowfall in east central IA.
If the northward track verifies, the majority of the precipitation will fall as rain during the morning prior to the passage of the cold front. A dry slot should then either end or reduce precipitation until the evening when light deformation zone snowfall overspreads the area. Saturday night, a strong pressure gradient increases as the low pushes towards the east.
- bill s
5:04 PM CST, 12/10/10
A powerful winter storm will affect the upper-Midwest starting Saturday. The worst conditions will pass to our north, with more then a foot of snow with strong winds expected in the Twin Cities area. Here in eastern Iowa, precipitation will start after midnight as rain. A strong cold front will reach the Cedar Rapids and Iowa City area by late morning, with precipitation changing over to snow between 1 and 2 PM. Winds will increase out of the northwest during the afternoon, with gusts increasing to 50-60 mph or more by evening! Even with only a few inches of “powdery†snow, travel in rural areas will become difficult in much of eastern Iowa. Below is time of arrival and total snow accumulation for tonight’s event for specific locations in central and eastern IA:
Cedar Rapids, IA (Eastern IA Airport):
Rain will start at 1 AM tonight, and change to snow after 1 PM Saturday. Total snowfall: 3.5 inches.
Iowa City, IA:
Rain will start at 1 AM tonight, and change to snow after 1 PM Saturday. Total snowfall: 3.2 inches.
North Linn Co., IA (Paris and Coggon):
Rain will start at 1 AM tonight, and change to snow after 1 PM Saturday. Total snowfall: 3.8 inches.
Marengo, IA:
Rain will start shortly after midnight, and change to snow after 12 PM Saturday. Total snowfall: 3.4 inches.
Union, IA:
Rain will start at 11 PM, and change to snow after 11 AM Saturday. Total snowfall: 4.0 inches.
Discussion:
Forecast confidence remains low with snowpack-enhanced baroclinic zone over the area. Forecast models still differ considerably as to the track and evolution of the surface and 850mb lows. The UKMET is indicating a southerly bias with the low track, while the NAM and GFS continue to favor a more northerly solution.
Tonight, strong warm air advection ensues with precipitation breaking out as rain in most areas of eastern IA. A mixture of freezing rain and rain is likely along and north of US-20 where a deep snowpack is in place and surface temperatures are lower. Surface cyclogenesis will occur in Iowa Saturday along a strong baroclinic zone as a 145kt 300mb jet streak and a series of embedded shortwaves approach the area. The track will then follow the upper-dynamics, of which inconsistencies exist. Looking at 12Z upper-air data and satellite imagery, it appears as though the jet streak which will evolve into an upper-low is verifying stronger then most models indicate. It is possible that the upper-dynamics and surface system will follow a more southerly track, which would result in heavier snowfall in east central IA.
If the northward track verifies, the majority of the precipitation will fall as rain during the morning prior to the passage of the cold front. A dry slot should then either end or reduce precipitation until the evening when light deformation zone snowfall overspreads the area. Saturday night, a strong pressure gradient increases as the low pushes towards the east.
- bill s
5:04 PM CST, 12/10/10
Ryan Wichman
EF3
I will be very interested to see how this whole storm shakes out. I think that the overall track of this storm is well diagnosed by the NWS but the model trends back to the south throughout the day today has been fascinating. Not because it puts me into a significant snow band, but rather, I have never seen the models sling shot from one solution to another this close to an event.
For example (with respect to 06z SUN):
The 00z NAM run last night showed the surface low just E of Green Bay, WI and an open 500mb trough. In a linear pattern to the SW, the subsequent runs have trended the surface low back to just E of Milwaukee, WI. With an 500mb closed low near PIA.
The 00z GFS run last night showed the surface low near Flint, MI and an open 500mb trough. In the same linear pattern but shift to the SE of what the NAM showed, subsequent runs (to 18z) have trended the surface low back to near Chicago, IL. With a closed low near STL.
To a lesser extent the SREF has done the same, shifting the surface low track back to the SW by about 100 miles in its 3 runs today.
This is why forecasting is fun. You think you have a lock on the situation and then BAM...the models shift 400 miles north. And for the fun of it, they shift another 100 miles SW
For example (with respect to 06z SUN):
The 00z NAM run last night showed the surface low just E of Green Bay, WI and an open 500mb trough. In a linear pattern to the SW, the subsequent runs have trended the surface low back to just E of Milwaukee, WI. With an 500mb closed low near PIA.
The 00z GFS run last night showed the surface low near Flint, MI and an open 500mb trough. In the same linear pattern but shift to the SE of what the NAM showed, subsequent runs (to 18z) have trended the surface low back to near Chicago, IL. With a closed low near STL.
To a lesser extent the SREF has done the same, shifting the surface low track back to the SW by about 100 miles in its 3 runs today.
This is why forecasting is fun. You think you have a lock on the situation and then BAM...the models shift 400 miles north. And for the fun of it, they shift another 100 miles SW
Similar threads
