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Post by guyatacomputer - NE St. Peters on Nov 29, 2024 7:12:54 GMT -6
What's the current ground temp running? The upper 20s the past couple of mornings has, no doubt, brought it down considerably.
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Post by BRTNWXMAN on Nov 29, 2024 7:49:07 GMT -6
What's the current ground temp running? The upper 20s the past couple of mornings has, no doubt, brought it down considerably. I don't think surface temps will be an issue other than main roadways with the snow starting early in the day. |
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Post by Tilawn on Nov 29, 2024 7:55:08 GMT -6
What's the current ground temp running? The upper 20s the past couple of mornings has, no doubt, brought it down considerably. 2” ground temps still in the mid 30’s this morning. Personally think roads will be fine (unless heavy bursts of snow happens) due to marginal road temps and it falling mostly during the daylight hours. Wondering if the onset will be delayed due to the dry layer as well. |
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Post by Snowstorm920 on Nov 29, 2024 8:49:25 GMT -6
Latest NBM is a strike right through the metro.  |
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Post by Chris Higgins on Nov 29, 2024 10:00:10 GMT -6
I continue to be amazed by the consitency of the model projections for this system. The little shifts between runs have been very minor. And this this is such a small system, which makes it even more amazing. Of course, consistent does not always equal accurate. But it does tell us bout the predictability. The available data thia AM has also trended a little bit wetter.
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Post by mchafin on Nov 29, 2024 10:01:20 GMT -6
How much of a concern is the DAM? Is a lot of that wet saturating the layers of the atmosphere?
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Post by Chris Higgins on Nov 29, 2024 10:15:39 GMT -6
The DAM will likely limit the coverage/intensity of the snow outside the mesoscale banding...but within the narrow band(s) the snow may get pretty intense for a couple hours.
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Post by ndolan387 on Nov 29, 2024 10:50:44 GMT -6
I continue to be amazed by the consitency of the model projections for this system. The little shifts between runs have been very minor. And this this is such a small system, which makes it even more amazing. Of course, consistent does not always equal accurate. But it does tell us bout the predictability. The available data thia AM has also trended a little bit wetter. Yeah it has trended wetter and warmer. 850mb temps are more borderline on the second half of this system for areas in the southern STL metro. This looked like more of a dry snow days ago for much of the metro...looks more wet now. The 12z HRRR would say this is more of a dry snow and sets up 2 mesoscale bands. |
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Post by BRTNWXMAN on Nov 29, 2024 10:50:59 GMT -6
I continue to be amazed by the consitency of the model projections for this system. The little shifts between runs have been very minor. And this this is such a small system, which makes it even more amazing. Of course, consistent does not always equal accurate. But it does tell us bout the predictability. The available data thia AM has also trended a little bit wetter. The lead time forecast of this system is way beyond any low-amplitude clipper I've seen by far...they've been pretty well locked in for days now! |
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Post by ndolan387 on Nov 29, 2024 10:58:11 GMT -6
The high resolution NAM is further north while the HRRR is more WSW regarding one of the mesoscale bands. The other mesoscale band is further NE. Still think there's going to be two mesoscale bands. NWS is favoring along and north of I-70 as others have shared. Where these bands set up is going to be crucial in my opinion. As we know the atmosphere isn't socialistic especially when it comes to snow in our area!
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Post by Worldserieschampions (Chicago) on Nov 29, 2024 11:19:43 GMT -6
The high resolution NAM is further north while the HRRR is more WSW regarding one of the mesoscale bands. The other mesoscale band is further NE. Still think there's going to be two mesoscale bands. NWS is favoring along and north of I-70 as others have shared. Where these bands set up is going to be crucial in my opinion. As we know the atmosphere isn't socialistic especially when it comes to snow in our area! It’s a shame it doesn’t offer a social safety net of at least getting the ground covered |
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Post by Chris Higgins on Nov 29, 2024 11:22:00 GMT -6
The 15z RAP is quite healthy and right down the MO River.
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Post by showtime - Marissa on Nov 29, 2024 11:41:24 GMT -6
Have I ever mentioned how much I love the RAP lol
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Post by mchafin on Nov 29, 2024 11:46:40 GMT -6
Have I ever mentioned how much I love the RAP lol Old school rap is pretty good, I agree. |
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Post by ndolan387 on Nov 29, 2024 12:10:55 GMT -6
Our clipper looks disorganized in Eastern and SE Nebraska right now. Going to be fun to see the evolution of it as it moves along or near the Missouri River Valley Region to the ESE.
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Post by BRTNWXMAN on Nov 29, 2024 12:59:21 GMT -6
Our clipper looks disorganized in Eastern and SE Nebraska right now. Going to be fun to see the evolution of it as it moves along or near the Missouri River Valley Region to the ESE. Short range models from yesterday showed it really coming together quickly across E NE and NW MO late this evening/overnight. |
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Post by Chris Higgins on Nov 29, 2024 12:59:28 GMT -6
I've been taking in the new morning weather data in between cleaning up after a fantastic Thanksgiving feast! I hope you all were able to enjoy a beautiful day as well! LATEST DATA... So the latest data continues to strongly suggest a good portion of our viewing area will see snow Saturday. Many will see some accumulating snow... some will not. Such is the case with winter weather in this part of the country. This is especially true with a small system like this Clipper. The system will spread a very narrow band of snow from northwest to southeast across the region. While there is still variability in the signals for the exact location of the heaviest band of snow..all available data is focusing the core of the accumulating snow to be near or just north of the Missouri River...and right into the metro STL area. TIMING... Snow is expected to begin during the morning hours west of St. Louis and then rapidly expand in a narrow ribbon to the east into metro STL before noon. From there, the ribbon of snow will spread into southern Illinois. The snow will last from 3 to 5 hours within this band...and at the peak of the storm...the snow may briefly be moderate to heavy for an hour or so. WHERE WILL IT SNOW AND NOT SNOW... Areas south of a line from Sullivan to Ste. Genevieve are not likely to see much... if any snow... much less any accumulations. In fact, temperatures down south of that line will be well above freezing and there could even be some light rain. North of that line is where conditions will resemble a winter wonderland... with big sloppy wet snowflakes quickly accumulating on grassy surfaces with temperatures near or just below freezing. PEAK STORM TIME... Atn this time, it appears te peak of the storm is likely to be from 10AM to 2PM across the metro. ACCUMULATIONS.... Snowfall totals will vary significantly from north to the south with a very sharp cutoff between the "haves" to the north and "have-nots" to the south. The center of the heaviest snow totals of 2-3 inches will run along I-70 and the Missouri River into the northwest metro. South of there, I'm going with "dusting to 2 inch" wording because of that sharp cutoff. It could literally go from 2 inches to almost nothing over just a couple of miles... and that cutoff looks to line-up somewhere from Franklin into Jefferson County in Missouri at this time. IMPACTS... Untreated surfaces will get slushy for sure... but treated surfaces will be mainly just wet. The exception might be during that 1 to 2 hour period at the max of the storm when the snowfall rates may be heavy enough to briefly turn even treated roads a little slushy. Overall, this still registers as a minor impact winter weather event for most areas... but may briefly reach moderate impact for a couple of hours around midday. This being the first snowfall, it is a good time to remind everyone (myself included) that anytime ice is falling from the sky, there is a chance for slick/slushy spots... even if the roads just look wet. Be smart and enjoy the beauty and magic of the first snow of the season in many spots.       |
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Post by Chris Higgins on Nov 29, 2024 13:04:51 GMT -6
To add to my formal post above...
I do have concern about a very very narrow band of 3+ snowfall somewhere between I-70 and the Missouri River if the mesoscale band remains nearly stationary.
There are a number of indicators that are quite a bit south of the ensemble means...including our in house IBM Graf model. I think those are likely too far south and my forecast basically splits the difference between the centroid of the ensmble guidance and the northern edge of the southern most runs...that also seems to match the northern extent of the 850mb jet before it lifts upwards towards 700mb. That LLJ is pretty solid with this system which indicates the lift in the presence of a tightening thermal graident should be pretty robust for a couple of hours near the Missouri River and I-70. I think we may get a few spots that overperform.
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Post by Frivolousz21 on Nov 29, 2024 13:34:41 GMT -6
Pwats are pretty damn good for the Northern edge of a small system like this.
Definitely viable moisture to be worked with.
Infact there is a small period that is currently underway where moisture from the SW Pacific jet is being fed into the Northern jet.
The models are all much wetter today it looks.
The nam and GFS took a huge North turn.
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Post by Snowman99 on Nov 29, 2024 13:41:38 GMT -6
Dammit. Gimme an inch in union
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Post by jmg378s on Nov 29, 2024 13:46:53 GMT -6
18z HRRR coming in fairly wet, probably too wet, showing 1/2-1"/hr snow rates. Placement is further south than the NAM/GEFS and even the ECMWF/ICON. Metro area, especially the northwest suburbs, is looking pretty good when you blend it altogether.
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Post by bellevillewxguy on Nov 29, 2024 13:59:38 GMT -6
18z HRRR coming in fairly wet, probably too wet, showing 1/2-1"/hr snow rates. Placement is further south than the NAM/GEFS and even the ECMWF/ICON. Metro area, especially the northwest suburbs, is looking pretty good when you blend it altogether. 18Z HRRR showing Belleville some love... |
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Post by bellevillewxguy on Nov 29, 2024 14:04:38 GMT -6
18NAM looks to be just as fun.
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Post by showtime - Marissa on Nov 29, 2024 14:24:02 GMT -6
First WW advisory of the season…… says 2-4 for most of the area
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Post by Chris Higgins on Nov 29, 2024 14:24:19 GMT -6
Winter Weather Advisory hoisted.
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Post by Snowman99 on Nov 29, 2024 14:32:55 GMT -6
Dammit
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Post by Jeffmw on Nov 29, 2024 14:34:17 GMT -6
Winter Weather Advisory hoisted. Chris what caused them to issue the WWA? |
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Post by mchafin on Nov 29, 2024 14:35:35 GMT -6
That sure is one narrow WWA!
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Post by Chris Higgins on Nov 29, 2024 14:36:07 GMT -6
Winter Weather Advisory hoisted. Chris what caused them to issue the WWA? We are now within 24 hours of the first snow event of the season and there are likely to be some minor impacts to travel. Nothing really changed. |
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Post by bellevillewxguy on Nov 29, 2024 15:00:17 GMT -6
Tomorrow just has the looks of an over-performer. Lapse Rates are solid, dynamics maxing out as it moves through East Central Missouri into the metro gradually waning. Even some training of the meso bands for 3-6 hours is gonna get someone over 6" and Wentzville, MO to O'Fallon, IL looks to be prime target.
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