Severe Weather/Winter Storm - 3/26 to 3/28

[venture]

How do you all know so much about this stuff?

Are you all storm chasers?

It's what I went to OU for, then got into IT sales. Go figure.
I didn't chase last year, started chasing though in 1996.

[Thunder]

KOCO is being very caution about all of this. With their latest update, there isn't much details and the message they deliver is more grim than excitement.

Surely we must have something major! This thread is the only excitement I can find. lol

[venture]

Spotter confirmed brief touchdown on storm across red river. Add'l storms beginning to form north and south of the existing one.

Since we are on a new page, gonna bring the radar with it.

[venture]

Spotters confirm tornado on the ground, NWS Ft Worth is apparently a sleep right now. T-Storm Watch now issued for south central Oklahoma and NC Texas.

Update: 743PM CDT...NWS Fort Worth finally woke up. Tornado warning on that storm. New storm near Ardmore continues to increase in strength.

[venture]

Still waiting on the evening model runs to finish, right now my snowfall forecast will get fine tuned a bit - but no major changes really. From what I'm seeing, OKC will probably get painted in the 3-6" area on my map, but everything else seems pretty well in line.

[OKCisOK4me]

Still waiting on the evening model runs to finish, right now my snowfall forecast will get fine tuned a bit - but no major changes really. From what I'm seeing, OKC will probably get painted in the 3-6" area on my map, but everything else seems pretty well in line.

So then what's up with the map Jonathan Conder put out that has everything north and west of I-44 in OKC painted with 6-12"?

[venture]

3-6" doesn't drive headlines does it? : )

Not everything is in yet, still waiting on 2 other models to finish up. However, from the ones that are available for this time period, the wrap around area looks like it is going to get chewed up by the dry slot quick. I'll wait until everything else is processed before rolling out an updated map, there may be something in there that I'm not seeing in the others.

Lot of things could still be in play. I wouldn't be shocked if areas south of Oklahoma County (Norman and such) didn't get any accumulation at all.

[OKCisOK4me]

Well, we'll find out here in about 3 minutes!

[Luke]

I'll be interested to see what each of the newschannels are predicting tonight. Let me know what you guys find out.

[venture]

KFOR was 3-7", KOCO 3-6"...forgot what KOKH had, and KWTV will be up after BBall.

[rod4soonrs]

[rod4soonrs]

[Thunder]

KFOR finally got the entire OKC metro areas within the likely track and the 16" color shade had gotten a lot closer to OKC.

[rod4soonrs]

look for OK cnty to be upgraded to a winter storm warning before 6AM, this storm is slowing and moving more to the south.

[Curt]

Venture let me throw out this question for you crazy as it may sound...I live just east of Detroit metro airport and alot of not only winter storms but also summer storms that are shown comming our way seem to actually split and go north and south of us in Dearborn...would the heavy airplane traffic currents have anything to do with this or could possibly the difference in air temps around the airport have any kind of affect on the weather directly east of a large airport such as DTW?

[venture]

Venture let me throw out this question for you crazy as it may sound...I live just east of Detroit metro airport and alot of not only winter storms but also summer storms that are shown comming our way seem to actually split and go north and south of us in Dearborn...would the heavy airplane traffic currents have anything to do with this or could possibly the difference in air temps around the airport have any kind of affect on the weather directly east of a large airport such as DTW?

Romulus is a scary place, so I would split in two to avoid it as well. ; ) Just kidding. I use to live up there, so I know what you mean. I would think the biggest impact you'll see is the lake breeze and which way it is blowing. I know if you looked south in Toledo, they go through the same thing when there is a nice NE wind. That area is really weird with weather, but also sharpens your skills. So many impacting factors can throw a forecast completely off.

[Curt]

Romulus is a scary place, so I would split in two to avoid it as well. ; ) Just kidding. I use to live up there, so I know what you mean. I would think the biggest impact you'll see is the lake breeze and which way it is blowing. I know if you looked south in Toledo, they go through the same thing when there is a nice NE wind. That area is really weird with weather, but also sharpens your skills. So many impacting factors can throw a forecast completely off.

Romulus is indeed a good place to avoid especially at night...no joking there..I do know the weather kind of stalls over eastern Mi. because of the warm air comming up off of Lake Huron which is why the eastern half of the state gets more clouds than the western half...but thanks for your input

[venture]

Mmmk...here is my updated look based on the models tonight.



Some of the snow totals are a little bit lower out west, really this should be placed with an note that convective banding of the snow is going to be key. There will be areas with over 12" of snow out there, and I could probably have painted the whole thing 12-24, but I wanted to keep things a bit more realistic based on what forecast guidance is showing. The heavy snow area has been expanded a bit more in NW Oklahoma, but the eastward extent of it has been cut back. It does look like this system will quickly get dry slotted and shut down the snow machine quickly on Saturday. I did though extend a general moderate snow of 3-6 throughout the NE part of the state as the storm pulls away. There does looked to be a significant wrap around band set, and that is where the larger totals will be. The area of 12-24" is the best guess where it will be. It could be further west, north, or east than that. We'll have to see. I decided to paint the OKC area for the most part in 3-6" given the nature of around an 0.5-1.0" of snow per hour in this area will at least yield these totals. The 6-12" area in NC Oklahoma was beaten back, if the wrap around band hangs on longer, this will spread further to the east again.

So what else could bust this. Slow change over to snow, mixing of sleet, and very wet grounds. Showers and Storms are expected to develop tonight that will get the ground nice and wet. This will impact accumulations. From what it looks like now, precip will cut off early enough that there will not be a change over back to rain as the mid levels warm through Saturday Afternoon/Evening.

Metro Outlook...I would imagine they'll upgrade to a Winter Storm Warning, based on being "close enough" to criteria, though the event really won't get out of control that a Snow Advisory would normally handle elsewhere in the Country. I would imagine the area north of I-40 will be under the warning, south of I-40 will be handled with a Winter Weather Advisory, well this is Oklahoma, so they'll go with a Snow Advisory.

[venture]

No major updates this morning. Will tweak snowfall forecasts a bit, but they seem good for all areas, just need a little adjusting (at least in western Oklahoma). Warnings were modified, but reasoning for warnings is going to be winds causing blowing and drifting and not snowfall amounts (at least in Metro area). Most snowfall amounts in the Metro will be below Winter Storm Warnings criteria. Severe weather is ongoing in a couple western counties as well, with one hail storm. Other storms are developing ahead of the cold front, so isolated severe hail will be a risk until front passes and change over occurs.

[Thunder]

Oklahoma City Weather Radar, Oklahoma City, Oklahoma Interactive Weather Radar - KOCO

Zoom out a couple time, get a more wide view of the state and out west.

Set the Opacity to 0% and click Animate.

You get the idea how heavy the rain and snow is falling right now.

I find it quite hard to believe there is a dryline anywhere between New Mexico thru Texas to OKC. The moisture is all there. It is truely amazing! I don't think we have to worry bout a dryline mysteriously appear to choke the system.



You can see the northern part is spreading into Kansas. Those will continue to move E/NE according to tracking the movement overnight.

The southern side from New Mexico on thru Texas and now entering Oklahoma is increasing in strength and size. Note the shades of the blue. I've been tracking this all night and had noticed it is growing quite well.

The only factor is how soon will OKC's surface temp drop low enough for these snow to maintain their bulky flakes? It'll be quite some time, anywhere after 5pm, unless the storm does something really intense to shove the temp down (kinda like heat burst in summer storms). I do think the cold/cool rain help the ground, with water, the temp will lower more quicker as time goes on.

Now we wait just where this and that heavy bands will hit.

[venture]

Discussion regarding Severe Potential...

MESOSCALE DISCUSSION 0291
NWS STORM PREDICTION CENTER NORMAN OK
0650 AM CDT FRI MAR 27 2009

AREAS AFFECTED...WRN INTO CENTRAL OK

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 271150Z - 271315Z

ELEVATED THUNDERSTORMS WITH A THREAT FOR LARGE HAIL MAY CONTINUE TO INCREASE THROUGH THE MORNING. AREA IS BEING MONITORED FOR A SEVERE THUNDERSTORM WATCH.

STRONG UPPER TROUGH/CLOSED LOW CENTERED OVER NM WILL CONTINUE TO FOCUS LARGE SCALE ASCENT ACROSS THE SRN PLAINS THROUGH THE MORNING.
MEANWHILE...LOW LEVEL CYCLONE AHEAD OF THE UPR TROUGH IS EXPECTED TO REMAIN QUASI-STATIONARY OVER TX THROUGH MUCH OF THE MORNING...AND THEN EJECT EASTWARD AS PROMINENT S/W TROUGH ROUNDING THE BASE OF THE CLOSED LOW EMERGES OVER THE SRN PLAINS. LOW LEVEL WAA/ISENTROPIC ASCENT LOCATED N-S OVER WRN/CENTRAL OK WILL PROVIDE A FOCUS FOR THUNDERSTORM INITIATION. RUC FORECAST SOUNDINGS INDICATE STEEP MID LEVEL LAPSE RATES ARE PRESENT OVER THE DISCUSSION AREA /AOA 8 C PER KM IN THE 700-500 MB LAYER/...WITH A MOIST/SATURATED AIRMASS LOCATED BELOW ROUGHLY 700 MB. PARCELS ROOTED IN THE 700-650 MB LAYER MAY EXPERIENCE MUCAPE VALUES UP TO 500 J/KG AS THE MORNING PROGRESSES...WITH EFFECTIVE CLOUD LAYER SHEAR ON THE ORDER OF 40-50 KT. THUS...UPDRAFT ROTATION WITHIN THE STRONGER STORMS IS POSSIBLE...POSING A THREAT FOR LARGE HAIL. IF THUNDERSTORMS CONTINUE TO INCREASE IN COVERAGE AND INTENSITY...PORTIONS OF WRN/CENTRAL OK MAY REQUIRE A SEVERE THUNDERSTORM WATCH.

[venture]

I find it quite hard to believe there is a dryline anywhere between New Mexico thru Texas to OKC. The moisture is all there. It is truely amazing! I don't think we have to worry bout a dryline mysteriously appear to choke the system.

The southern side from New Mexico on thru Texas and now entering Oklahoma is increasing in strength and size. Note the shades of the blue. I've been tracking this all night and had noticed it is growing quite well.

The only factor is how soon will OKC's surface temp drop low enough for these snow to maintain their bulky flakes? It'll be quite some time, anywhere after 5pm, unless the storm does something really intense to shove the temp down (kinda like heat burst in summer storms). I do think the cold/cool rain help the ground, with water, the temp will lower more quicker as time goes on.

I'll hit each of your points really quick. Moisture is there, that isn't an issue. However, as typical with winter storms they will dry slot as they mature. At current, there is no dryline feature, and I wouldn't expect one for the course of the event - we are in winter mode now.

Precip rates seem to be growing on radar because 1) the storm is coming into better moisture and 2) the radars are not as obstructed by landmass formations as they were in earlier areas.

OKC's temp should drop between 4-7. This raid this morning will only cool the air so much. Right now there is only a 2-3 degree spread from air and dewpoint temps, so the temps aren't falling much further until the cold front comes through later today. Saturated ground will impact snow visible snowfall amounts (to the negative) until snowfall rates increase enough to overcome melting.

[Thunder]

Question.

Will the cold front come thru behind the system or ahead of the system?

[venture]

Here is a good depiction where the front is now:



It is currently not expected to make I-35/I-44 corridor until around 5-7PM. NWS Norman is calling for change over in OKC proper around 6PM this evening. The front will come through and then you will see the low track along it some what, and main snow event will be in the wrap around area.

[venture]

Looks like icing has occurred in far Northwest OK that is making conditions much worse. If change over to snow takes much longer, significant ice accumulations will continue to bring power lines and poles down at a greater rate.