General Weather Discussion - December 2018

[Anonymous.]

New month time. Tomorrow (Friday) will be mild and humid ahead of a strong storm system. C OK could see some storms develop directly overhead afternoon into evening Friday, but it is unlikely. The more likely scenario is development taking place east of C OK. Far E OK could see some solid severe weather overnight.

After that, 60s again Saturday, and 50s Sunday. Cold air really starts to filter in heading into next week. Highs will struggle to get out of the 40s for the entire week.


Going to go ahead and say preliminary Bread & Milk Watch for next weekend December 7th-ish. A storm will be in the area with iffy temperatures.

[Anonymous.]

Warmfront boundary essentially has C OK split in half and a dryline retreating much further west than forecast. This will setup C OK for possible development of storms this afternoon just west of OKC. Storms will likely be supercell in nature and have non-zero tornado potential. Although it is likely storm maturity may not be fully realized until they pass OKC, keep eye on radar and local weather in the 5-8pm time frame.


I would place emphasis on any storms that develop immediately west of OKC in the Anadarko - El Reno - Yukon corridor for keeping closest eyes on.

[Anonymous.]

MD is out. Tornado watch coming in next hour.

Mesoscale Discussion 1668
NWS Storm Prediction Center Norman OK
0351 PM CST Fri Nov 30 2018

Areas affected...portions of north-central tx into central ok

Concerning...Severe potential...Watch likely

Valid 302151Z - 302315Z

Probability of Watch Issuance...80 percent

SUMMARY...Severe threat will increase after 23z from portions of
north-central TX into central OK. Large hail is likely with this
activity along with some tornado threat. WW will likely be issued by
00z.

DISCUSSION...Leading edge of large-scale ascent is spreading east
across the southern High Plains at roughly 30kt. Latest visible
satellite imagery supports this with blowing dust and strong
westerly surface flow approaching southwest OK. Strengthening
mid-level height falls, on the order of 150-210m, during the latter
half of the period are inducing a focused low-level response across
the Red River valley into central OK. Modified Gulf air mass has now
spread into all but extreme southwest OK with mid 50s surface dew
points now into Jackson County. Over the next few hours, near 60 dew
points are expected to advance into central OK. Given the
aforementioned speed of approaching large-scale forcing, latest
thinking is deep convection should develop by 23z over southwest OK,
perhaps extending south of the Red River into northwest TX. Very
strong shear and steep mid-level lapse rates will support supercell
development by early evening. Large hail is expected with this
initial activity. As convection spreads toward the I-35 corridor a
bit more moist profiles will become more supportive of potential
tornadic development, especially where lower-mid 60s dew points are
encountered. Back edge of severe convection should shift east of
I-35 by 03z.

..Darrow/Hart.. 11/30/2018

[Anonymous.]

[Anonymous.]

Also I just realized I am posting all of this in December.. Oh well. lol

[Anonymous.]

TOR watch is out:

[Bunty]

Tornado Watch - Includes all Oklahoma City Metro Area
Updated: Fri Nov-30-18 05:21pm CST
Effective: Fri Nov-30-18 05:20pm CST
Expires: Sat Dec-01-18 12:00am CST

Severity: Severe
Urgency: Expected
Certainty: Likely

Status: Actual
Type: Alert
Category: Met

TORNADO WATCH 429 IS IN EFFECT UNTIL 1200 AM CST
OKLAHOMA COUNTIES INCLUDED ARE
ADAIR ATOKA BRYAN
CADDO CANADIAN CARTER
CHEROKEE CHOCTAW CLEVELAND
COAL COMANCHE COTTON
CRAIG CREEK DELAWARE
GARVIN GRADY HASKELL
HUGHES JEFFERSON JOHNSTON
KINGFISHER LATIMER LE FLORE
LINCOLN LOGAN LOVE
MARSHALL MAYES MCCLAIN
MCINTOSH MURRAY MUSKOGEE
NOBLE NOWATA OKFUSKEE
OKLAHOMA OKMULGEE OSAGE
OTTAWA PAWNEE PAYNE
PITTSBURG PONTOTOC POTTAWATOMIE
PUSHMATAHA ROGERS SEMINOLE
SEQUOYAH STEPHENS TILLMAN
TULSA WAGONER WASHINGTON
Counties covered in yellow.

[Hollywood]

You called it on the El Reno/Anadarko area!

[Anonymous.]

Cell east of Anadarko and N of Chickasha is ramping up some. Numerous cells are firing in the area, which will help limit any isolated supercells, but LLJ will kick in and may cause some isolation issues in a couple hours.

[Anonymous.]

That cell is the only game in the state right now. Hail size ramping up. Like I mentioned earlier today. OKC will probably get past these before full storm maturity and LLJ will make these more dangerous off to the east.

Right now hail is moving into Tuttle and soon S Mustang area.

SVR warnings issued for all C OK based on that cell described above.

[Anonymous.]

Main threat with the initial storms is heading out of OKC now ~7:30pm.

Strongest storm in state is backside and will be heading into W Duncan soon. Short-range models expand this backside development and race it back into OKC later tonight, but I have my doubts it develops that far north. I will keep watching radar.

[Anonymous.]

Okay looks like that last round of storms will actually impact OKC. Right now they are not severe, but are moving VERY fast. Gusty winds with the initial impact will be biggest threat. After these we will be in the all clear. Enjoy your windy Saturday.

[LocoAko]

All eyes now turn to the potential for a significant winter storm Thursday-Saturday. Models have some disagreement but it looks like ice and/or snow totals could be fairly high. First graphic out of NWS Norman:

[Anonymous.]

Classic southern plains winter storm still being picked up on by models. Temperatures and track will determine locations of impacts, but impacts do look to be significant wherever they take place.

We will get into NAM window in next couple days so we will have a better idea. But for now this is what we have model-wise.

GFS:
Start of storm: Freezing rain and sleet just NW of I-44 corridor. Snow in NW OK.
End of storm: Snow all of I-44 corridor and points N.

Canadian & GEM:
Start of storm: Freezing rain over I-44 corridor for prolonged period, potential major icestorm scenario. Snow in NW OK.
End of storm: Snow all of I-44 corridor and points N.


Will keep updating as we get into additional forecast model windows and obviously the less time gap before the event - the more accurate things will be painted.

[Bunty]

Story of the damages from tornado in eastern Oklahoma during Friday night with drone video.

https://ktul.com/news/local/severe-s...stern-oklahoma

[bradh]

Ha, go figure, we're coming back for a wedding this weekend. I'm sure we'll have to endure many "you guys brought this with you from Minnesota" jokes

Flying in Thursday night, outdoor wedding planned for Saturday afternoon....yay

[Anonymous.]

Outdoor wedding in the first week of December? Okay... Was it like free? haha

Tonight's model data is showing trend toward warmer temperatures at beginning of storm meaning more of a cold rain solution, then followed up by wrap-around snow on Saturday.

[bradh]

Yeah a little ambitious right?

[Bunty]

See Euro vs US GFS below.

[Bunty]

Euro vs US GFS

[Anonymous.]

First glimpses into the NAM do not paint a pretty picture. Major winterstorm per NAM. Whilst the GFS is backing off.

Will have more tomorrow when we have full storm data.

[sooner333]

First glimpses into the NAM do not paint a pretty picture. Major winterstorm per NAM. Whilst the GFS is backing off.

Will have more tomorrow when we have full storm data.

Which models are the best to look at for winter weather?

[jn1780]

Which models are the best to look at for winter weather?

I think the NAM is often used for shorter term forecasting? I know the window that forecast models come out is a lot smaller.

[Anonymous.]

There is only a few long-range models that are commonly used in forecasting. However, once you get into the 24-72 hour window of an event you are forecasting, there is a lot of models that are viable. Obviously, the closer you are to an event - the more confident the forecast. Since this storm is very large, it will be a multi-day event, so the entire storm is not in short-range models' view until very close to the start of the event.

By lunchtime Wednesday we will have a full-storm length picture of the storm in the NAM window and we will be able to begin fine-tuning Wednesday night into Thursday using a conglomerate of all of the model data and excluding anomalies.

As of tonight, the NAM is full doomsday
GFS seems out to lunch on temperatures, but more realistic on QPF.
Canadian and GEM are sort of in-between the above.

[SoonerDave]

Obviously the official interpretation will come from Anon, but it seems both the latest GFS and the NAM are backing off the worst Friday daytime predictions and pushing the worst of this as an overnight Friday/Saturday daytime event.