Severe Wx Event Nov. 29 - Dec. 1, Southern and Eastern CONUS

[wxmann_91]

SPC outlook: http://www.spc.noaa.gov/products/exper/day4-8/

Latest GFS, ECMWF, and CMC all agree on a large neutral-tilt trough developing in the western CONUS. GFS paints a 990 low in the Plains. Probably overdone, but nevertheless, interesting. Timing is crucial; the trend has been slower and more amplified which increases the threat.

I think we all know the GFS site but here's the ECMWF: Link (click on the link under "Deterministic medium-range forecast charts")

The CMC

Moisture could be an issue as a huge arctic high sits over Canada, and also, there has been a huge cP airmass intrusion all the way to the Caribbean from the latest storm which brought snows to Orlando. Slowing the system down increases wavelength and recovery time for the Gulf.

Finally, with such a large pressure gradient between the low in the CONUS and the high in Canada, along with the large reserve of arctic air, a blizzard is possible over the northern plains next week.

[Lindaloo]

Is this your thoughts?

[CrazyC83]

I'd say that this could be a combined blizzard and tornado outbreak on either side of a cold front. Good thing the Thanksgiving travel should be done in time!

[wxmann_91]

Is this your thoughts?

This is model interpretation. Not really "thoughts" per say but I guess it did take some thinking to come up with the post.

[Lindaloo]

Okay. Good job.

Now read it back to me so I can understand it. lol.

[wxmann_91]

Okay. Good job.

Now read it back to me so I can understand it. lol.

Thanks. lol

All right, in more simple terms:

The models are showing a trough in the western U.S. around next Tuesday. Normally, this is a classic pattern for severe wx across the Plains. We will have to watch the moisture though, because there has been a significant frontal passage over the last few days that has depleted the moisture in the GOM, so it will take several days to moderate that air and get the moisture back into the GOM so it can be drawn northward.

An arctic high will sit over Canada. The pressure gradient between this high and the low further south will create a strong pressure gradient, and with the cold air this high will funnel in, there's a chance that the northern plains could see a blizzard.

The latest run shows the trough not amplifying as much (figures), but is an improvement on the moisture side.

[Lindaloo]

Oh now I understand. Thank you very much!

[NEWeatherguy]

I read on another board areas such as eastern Nebraska and western Iowa (me!) may get in on some severe weather action. However, a lot of things would have to happen to bring this to fruition. I see it now (maybe ): tornado warnings in Omaha and blizzard warnings in Grand Island, Neb.

[NEWeatherguy]

I read on another board areas such as eastern Nebraska and western Iowa (me!) may get in on some severe weather action. However, a lot of things would have to happen to bring this to fruition. I see it now (maybe ): tornado warnings in Omaha and blizzard warnings in Grand Island, Neb.

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

[NEWeatherguy]

My NWS office in Eastern Nebraska and southwest Iowa now has isolated thunderstorms in for our area Sunday night and Monday! Des Moines, Iowa, NWS said a few marginally-severe gusts are possible, but that is about it.

Then, we may see some fluffy white stuff. However, it does not look like a big deal.

Kind of excited to see some sort of precipitation/moisture. It is dry here.

[Extremeweatherguy]

My NWS office in Eastern Nebraska and southwest Iowa now has isolated thunderstorms in for our area Sunday night and Monday! Des Moines, Iowa, NWS said a few marginally-severe gusts are possible, but that is about it.

Then, we may see some fluffy white stuff. However, it does not look like a big deal.

Kind of excited to see some sort of precipitation/moisture. It is dry here.

If JB is right then Omaha will not get out of the teens for a day or two late next week. If nothing else, it will be very cold.

[CrazyC83]

I read on another board areas such as eastern Nebraska and western Iowa (me!) may get in on some severe weather action. However, a lot of things would have to happen to bring this to fruition. I see it now (maybe ): tornado warnings in Omaha and blizzard warnings in Grand Island, Neb.

Or a tornado warning and a blizzard warning concurrently in the same region (based on the movement of the cold front)...

[wxmann_91]

I'll update this. The latest models do not dig the trough as deeply, and moisture return is meager. Still there might be a slight chance of severe wx down in the southeastern U.S.

[CrazyC83]

It's a crapshoot now.

[NEWeatherguy]

I am not as impressed with this system as I was earlier. I do think there may be isolated storms that may become frisky as far north as the I-80 corridor from Omaha to Des Moines, Iowa, but anything serious, i.e. an outbreak or something close to an outbreak, appears very low at this time.

[Weatherfreak14]

I am not as impressed with this system as I was earlier. I do think there may be isolated storms that may become frisky as far north as the I-80 corridor from Omaha to Des Moines, Iowa, but anything serious, i.e. an outbreak or something close to an outbreak, appears very low at this time.

I agree the models tend toward a more of a shower/rain maybe 1 or two strong to severe storms the way it looks right now. Following this system it looks like it will be a snow maker for northern states maybe as far south as tennesse but thats about it.

[CrazyC83]

The SPC has become a lot more aggressive. 30% for Thursday (Day 3) in the MS valley, and mention on Friday all the way into the Mid-Atlantic.

[CrazyC83]

Even up here, this could get interesting - supposed to be in the 60s on Wednesday and Thursday - and in the teens on Friday.

[wxmann_91]

Based on model data, I'm inclined to believe tomorrow could be quite a nice dryline event across N central Texas into south central OK. Wednesday's threat looks more marginal due to weak lapse rates, resulting in terrible instability.

Will change the title Nov. 28-30 to reflect SPC adding a thraat area in their 4-8 day outlook across the Carolinas.

[CrazyC83]

Based on model data, I'm inclined to believe tomorrow could be quite a nice dryline event across N central Texas into south central OK. Wednesday's threat looks more marginal due to weak lapse rates, resulting in terrible instability.

Will change the title Nov. 28-30 to reflect SPC adding a thraat area in their 4-8 day outlook across the Carolinas.

It should be through Dec. 1 across the mid-Atlantic.