So their going on the belief that GFS isn't completely crazy and the front will end up somewhere in northern oklahoma.

I think they have to give the GFS something since ECMWF has been backing it up a good deal. However NAM has been persistent so you have to give it something to. Seems like they are doing a blend of them which is probably the best idea right now.

15% hatched Tornado area for today is along and west/south of a line from Ardmore to 13 mi E of Pauls Valley to Norman to 8 mi NE of Cordell to Hollis.

One thing everyone should take a look at in regards to the NAM's stubbornness is the northerly wind direction it is forecasting at the surface to the north of the warm front. This is fairly atypical in regards to normal patterns you would see in this case of a northward advancing warm front and one of the reasons it is keeping the frontal position much further to the south.

Now, when comparing this to current surface obs one can see that winds to the north of the WF are currently light but more out of the ENE (as they should be in this situation) and the WF has already begun its quicker move to the north - having already nearly reached Purcell at 6am. Thus, while I think the GFS is too extreme in terms of pulling the WF all the way up into KS, the NAM has not handled the sfc winds very well. And when you are dealing with a very shallow cold airmass as we were last week, those sfc winds can make quite the difference.

ESE Winds at Norman already...Warm Front is here. This is 3-4 hours ahead of schedule.

Also no on going storms right now. Get ready for a long day.

Just woke up. Warm front is trucking along nicely. Observing surface winds, the front has already made it from about Lawton to S OKC to Tulsa.

Would still like to see it move about another 30-60 miles NW. But it looks like it is going to happen.

Surface winds show the front is definitely on the move.

Moderate risk remains. The enhanced tornado threat(15%) has been expanded to include areas along I-44.

I'm surprised a tornado watch hasn't been issued yet by the NWS

I'm surprised a tornado watch hasn't been issued yet by the NWS

I would suspect they are holding off pending a better idea of the movement of the front. If it is moving as aggressively as some folks here have indicated, they may have that answer sooner rather than later.

Watches typically cover a 6 hour period. You won't see one until we are closer to initiation of convection.

New Outlook...

http://www.spc.noaa.gov/products/outlook/day1otlk_1300.gif

http://www.spc.noaa.gov/products/outlook/day1probotlk_1300_torn.gif

...OK/WESTERN NORTH TX/SOUTHEAST KS...
THE MORNING SURFACE ANALYSIS SHOWS A WARM FRONT EXTENDING FROM
SOUTHWEST TO NORTHEAST OK. THIS BOUNDARY IS RAPIDLY RETREATING
NORTHWARD AND IS EXPECTED TO LIE ROUGHLY FROM WEST-CENTRAL OK INTO
SOUTHEAST KS BY MID AFTERNOON. RICH LOW LEVEL MOISTURE SOUTH OF THE
BOUNDARY WILL COMBINE WITH AMPLE DAYTIME HEATING TO YIELD AFTERNOON
MLCAPE VALUES OF 3000+ J/KG OVER MOST OF THE SOUTHEAST HALF OF OK
AND SOUTHEAST KS.

VARIOUS MODEL SOLUTIONS CONTINUE TO STRUGGLE WITH SHORT-TERM DETAILS
OF CONVECTIVE POTENTIAL. THIS APPEARS TO BE DUE TO HANDLING OF
SUBTROPICAL SHORTWAVE SEEN IN WATER VAPOR IMAGERY OVER SOUTHERN NM.
LARGE SCALE FORCING FOR ASCENT WILL OVERSPREAD OK THROUGHOUT THE DAY
IN ADVANCE OF THIS SYSTEM...BUT IT APPEARS THAT 700MB TEMPERATURES
APPROACHING 10C WILL SUPPRESS SIGNIFICANT CONVECTION OVER
WESTERN/CENTRAL OK UNTIL THIS AFTERNOON WHEN PERSISTENT LIFT AND
STRONG HEATING WILL WEAKEN THE CAP IN VICINITY OF THE DRYLINE.

PRESENT INDICATIONS ARE THAT ISOLATED THUNDERSTORMS WILL DEVELOP BY
LATE AFTERNOON ALONG THE DRYLINE IN SOUTHWEST OK AND WESTERN NORTH
TX...AND ALONG THE STALLED BOUNDARY EXTENDING ACROSS NORTH CENTRAL
OK INTO SOUTHEAST KS. VERTICAL SHEAR PROFILES WILL BE QUITE STRONG
THROUGHOUT THIS AREA WITH 0-3KM SRH VALUES EXCEEDING 300 M2/S2 AND
STRONG EFFECTIVE SHEAR. DISCRETE SUPERCELL STORMS ARE EXPECTED WITH
A RESULTANT RISK OF VERY LARGE HAIL AND A FEW STRONG TORNADOES.
THESE STORMS ARE EXPECTED TO TRACK NORTHEASTWARD ALONG AND SOUTH OF
THE SURFACE BOUNDARY INTO NORTHEAST OK AND EVENTUALLY WESTERN MO
THIS EVENING.

Morning Sounding from Norman...

http://climate.cod.edu/data/raob/KOUN/skewt/KOUN.skewt.20130417.12.gif

Sfc dewpoint just jumped from 55-67 in Norman in 20 minutes. Yikes.

Not that it matters at this point because everyone needs to be on the lookout today, but are we looking at a high end moderate risk with the possibility of it being high end?

Venture, given the uncertainty regarding instability discussed here:

"VARIOUS MODEL SOLUTIONS CONTINUE TO STRUGGLE WITH SHORT-TERM DETAILS
OF CONVECTIVE POTENTIAL. "

Is that the only thing preventing them from issuing a PDS at some point? Sure seems to me you have all the other ingredients, unfortunately.

Not that it matters at this point because everyone needs to be on the lookout today, but are we looking at a highend moderate risk with the possibility at being high end?

Yes, I would say at this point OKC seems to be a central point of the moderate-risk area as painted by the Storm Prediction Center. I'm sure SPC will continue to monitor the situation and has left the possibility open to upgrading to high risk in the next outlook.

Model details would not have an impact on the type of tornado watch issued rather the level of risk (slight/moderate/high) and the location of said risk area. At this point considering current trends I would say any tor watch issued in the moderate risk area later today will have a high likelihood of being a PDS (Particularly Dangerous Situation) tornado watch.


Venture, given the uncertainty regarding instability discussed here:

"VARIOUS MODEL SOLUTIONS CONTINUE TO STRUGGLE WITH SHORT-TERM DETAILS
OF CONVECTIVE POTENTIAL. "

Is that the only thing preventing them from issuing a PDS at some point? Sure seems to me you have all the other ingredients, unfortunately.

I don't know if they have ever upgraded to HIGH from MOD hours away from an event before, I am not sure how to research such. But I doubt they would in this situation. I think increasing the parameters for tornado potential in the hatched area is a definite possibility and even likely heading into this afternoon.


One thing to keep in mind, as this warm front surged in - high based fog and drizzle like conditions will continue to develop as the air becomes rapidly saturated with moisture. Based on the trajectory of the front, I would not be surprised to see the MODERATE risk expanded further NW.

As the visible satellite imagery comes in (sun rises [earth spins]) - there is an obvious low deck of hanging clouds over much of OK and TX. The sun will attempt to burn off as much as possible, but the moisture content of this southerly air is so dense that it may have some trouble. This is the potential wrench in this weather machine today. Everything else is lining up to be a significant event. If we get some clearing towards SW and W C OK, look out!

At 530am temp/dewpt at OUN was 55/52. 3 hours later and it is now 71/68. Now THAT is a warm front.

This is pure gulf moisture if I ever felt it. Nice good southern breeze bumping it in and temp jumps of 15 degrees in an hour as the front passes overhead.

As addressed by s00nr1, PDS is the watch type not outlook type. Based on the outlook, we'll have mostly PDS red boxes (tornado) across Oklahoma today.

Spent some time outside and the sun has tried to break through in a few areas already. Some nice blue sky behind this lower cloud deck. If this does get burnt off, watch out.

Anon...May 3rd we were slight risk until 1630 UTC when we got upgraded to Moderate. We went to High at the 2000 UTC update. So I won't be shocked if we see the sun break through and SPC pulls the trigger. Here is the Day 1 guidance on when you see a High Risk. We are at the maximum for a moderate risk in Hail and Tornado right now.

http://www.spc.noaa.gov/misc/prob_to_cat_day1_seetext.jpg

Warm front passage here at 4th and Bryant in Moore about 5 minutes ago. How did I know? Well, every window in the house fogged up instantly.

Warm front passage here at 4th and Bryant in Moore about 5 minutes ago. How did I know? Well, every window in the house fogged up instantly.

It is freaking soupy out there, that's for sure. It's been awhile since we've had moisture like this it seems.

Chat room is obviously going for today. The link is: Live Chat | Weather Spotlight (http://www.weatherspotlight.com/?page_id=40)

I'll be back and forth from it until the main show gets underway.

It looks like they are now saying a major snow/ice storm is possible for next week.

This year may break all kinds of records as we go into may still having freezing temperatures.

If history shows it to be the case, then I can definitely see SPC going to a HIGH risk in areas where the sun beats down early afternoon. Thanks for the info on May 3! I was unaware that they upgraded the outlook as the event progressed.

It looks like they are now saying a major snow/ice storm is possible for next week.

This year may break all kinds of records as we go into may still having freezing temperatures.

No way.... WTH

Some grabs from the latest HRRR.

http://rapidrefresh.noaa.gov/HRRR/from_jet/hrrr_jet/2013041710/t5/cape_t5sfc_f11.png

http://rapidrefresh.noaa.gov/HRRR/from_jet/hrrr_jet/2013041710/t5/1hsm_t5sfc_f10.png

http://rapidrefresh.noaa.gov/HRRR/from_jet/hrrr_jet/2013041710/t5/cref_t5sfc_f10.png

Am I reading that first image correctly in that SW OK already has CAPE values > 5000?????

Am I reading that first image correctly in that SW OK already has CAPE values > 5000?????

That's forecasted values at around 4PM.

That's forecasted values at around 4PM.

Oh, good grief, I really should learn to read. Sorry. :o

I hope we don't have any severe weather during 3-5pm. That's when I get off school and hang out with my friends sometimes at the mall

Oh, good grief, I really should learn to read. Sorry. :o

Don't feel bad, at least you can understand the graphs lol

Don't feel bad, at least you can understand the graphs lol

LOL Barely understand a few of them. Growing up in OK, got scared to death of weather as a kid, then as a I grew up, decided to try to learn a few things here and there. Probably know only enough to be dangerous, kinda like using WebMD to self-diagnose a muscle twitch and concluding you have about six different ghastly diseases :) LOL

But even this rank amateur can see today lining up badly. Persistence of this cloud deck is the next big marker to watch, seems to me. If that goes away/burns off, hoo boy....

It certainly feels like a bad day in the making. Doesn't help when my three Labs have gotten extremely and uncharacteristically restless in the backyard.

It certainly feels like a bad day in the making. Doesn't help when my three Labs have gotten extremely and uncharacteristically restless in the backyard.

Pets have been going nuts here too all morning. Yet they sleep through the earthquakes. :-P

Pets have been going nuts here too all morning. Yet they sleep through the earthquakes. :-P

Mine sleep through anything except treats and dinner.

Pets have been going nuts here too all morning. Yet they sleep through the earthquakes. :-P

My dogs are incredibly lazy and will sleep through anything. They were both kind of twitchy this morning, though.

Some initial development now over SW OK. This is along/ahead of the warm front down there.

http://www.mesonet.org/data/public/mesonet/maps/realtime/current.TAIR.grad.png?1366211264346

Pets have been going nuts here too all morning. Yet they sleep through the earthquakes. :-P

My dog hates thunderstorms and earthquakes, it goes nuts when there is a single noise of thunder

http://www.spc.noaa.gov/products/md/mcd0491.gif

MESOSCALE DISCUSSION 0491
NWS STORM PREDICTION CENTER NORMAN OK
0950 AM CDT WED APR 17 2013

AREAS AFFECTED...ERN KS INTO WRN/CENTRAL MO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 171450Z - 171545Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...A SEVERE WEATHER WATCH IS BEING CONSIDERED FOR ISSUANCE
THIS MORNING INTO THE AFTERNOON ACROSS ERN KS AND WRN/CENTRAL MO.

DISCUSSION...TRENDS IN VISIBLE SATELLITE IMAGERY AND REGIONAL RADARS
ACROSS SERN KS SHOWED AN INCREASE IN AN AGITATED CU FIELD...WHICH IS
LIKELY AN INDICATION OF INCREASING DEEP LAYER ASCENT SPREADING NEWD
ACROSS THIS REGION. ENHANCED CLOUDS ACROSS SRN KS INTO PARTS OF
CENTRAL OK MAY BE INDICATIVE OF INCREASING ASCENT ATTENDANT TO A 65
KT MIDLEVEL JET/IMPULSE CURRENTLY ANALYZED OVER SWRN KS TO ALONG THE
TX PANHANDLE/WRN OK BORDER...PER WATER VAPOR IMAGERY...AREA WIND
PROFILERS/WSR-88D VWP DATA AND OBJECTIVE ANALYSES.

THIS REGION OF ASCENT IN SERN KS IS LOCATED INVOF A WARM
FRONT...WHICH AT MID MORNING CONTINUED TO ADVANCE RAPIDLY NWD ACROSS
SERN KS AND NOW APPROACHING CENTRAL MO. LOW LEVEL WAA ATTENDANT TO
A STRONG SWLY LLJ EXTENDING INTO ERN KS TO NRN MO AND WITH THE
DISCUSSION AREA REMAINING IN A STRONGLY DIFFLUENT REGIME SUGGEST
CONVECTION WILL CONTINUE TO DEVELOP...WITH ADDITIONAL TSTM
DEVELOPMENT EXPECTED THIS MORNING INTO THE AFTERNOON.

RECENT RUNS OF THE HRRR AND THE 00Z 4 KM WRF-NSSL SUPPORT THIS
SCENARIO WITH TSTMS GRADUALLY INCREASING IN VICINITY OF AND S OF THE
NWD MOVING WARM FRONT. AN ENVIRONMENT ALREADY MODERATELY UNSTABLE
WITH STEEP MIDLEVEL LAPSE RATES WILL FAVOR HAIL SIZE OF AT LEAST
1.75 INCH IN DIAMETER. THE SWLY LLJ IS EXPECTED TO BACK TO SLY IN
RESPONSE TO HEIGHT FALLS SPREADING ACROSS THE CENTRAL/SRN PLAINS
TODAY AHEAD OF THE APPROACHING WRN U.S. LONGWAVE TROUGH. THIS WILL
INCREASE LOW LEVEL HODOGRAPH CURVATURE...ESPECIALLY BY AFTERNOON FOR
AN ENHANCED TORNADO THREAT.

..PETERS/KERR.. 04/17/2013

Echos popping up NE of Altus.

Cloud deck is too stubborn, energy is here.

There is some clear skies over a small area from Lawton to SW OKC.


Looks like the show is going to start early.

Visible sat image showing a few more breaks in the coulds over SW and South Central OK. Still a pretty thick cloud deck out there, but not sure if it really matters at this point. Latest mesoanalysis has CAPE values 2500 to over 3000 already south of the warm front. SPC indices for significant tornado probabilities are also increasing in this area of higher instability. If precip continues to hold off except for a few sporadic showers like we have now, threat will only go up.

If this early convection gets shoved off to the NNE quickly enough, it should enable accelerated cloud deck erosion over the SE 2/3 of OK.

Much of SE OK is covered in high clouds, and sunlight is still penetrating to the surface.

Echos popping up NE of Altus.

Cloud deck is too stubborn, energy is here.

There is some clear skies over a small area from Lawton to SW OKC.

Looks like the show is going to start early.

So far looks like they are struggling to really do anything. Get dbZ levels around 40 and then they fall right back off. So I'm not too concerned yet.

Here is a good map to keep track of how much added instability is ongoing over the state. This helps you determine the thickness of the cloud deck, when visible imagery can be misleading.


The brighter this map gets, the more PDS this event gets for later this afternoon.
http://www.mesonet.org/data/public/mesonet/maps/realtime/current.SRAD.grad.png

So what is the timeframe OKC may get sever weather or tornadoes?

NWS Norman ‏@NWSNorman (https://twitter.com/NWSNorman)5m (https://twitter.com/NWSNorman/status/324543372729663488)
We will be testing the NOAA Weather Radio warning alarm today at noon UNLESS we have storms ongoing. Make sure your radio is working! #okwx (https://twitter.com/search?q=%23okwx&src=hash)

It is going to be interesting to see the wording for the E KS and W MO watch.

So what is the timeframe OKC may get sever weather or tornadoes?

Just start being alert anytime after 1PM I would say. Can't nail it down anymore than that until things get going.

It is going to be interesting to see the wording for the E KS and W MO watch.

The MCD almost hints that they'll eventually do an upgrade to a tornado watch later.

starting to see peaks of the sun coming out, this can't be good

The NWS has a graphic that shows the front stalling out just north of OKC at 6. Could make things interesting around here.

Yeah appears to be thinning out pretty good now south of the front. Also some CU development now about 40-50 miles south of Childress in West Texas. That would be along the dryline out there.

Chat room is obviously going for today. The link is: Live Chat | Weather Spotlight (http://www.weatherspotlight.com/?page_id=40)

I'll be back and forth from it until the main show gets underway.

thanks

starting to see peaks of the sun coming out, this can't be good

Venture can correct if I'm wrong, but the erosion of the cloud deck may be less important if the CAPE values continue to increase as the frontal boundary passes/has passed. The whole issue of the erosion of the cloud deck would be to facilitate sun-based heating of the atmosphere to add to the instability of the region, but I think things are migrating to the point where its already sufficiently unstable that storms could fire up. If it clears off and does allow for heating, it just makes the situation more favorable for the worst weather. The storms that have been mentioned in the SW part of the state might hasten the erosion of that cloud deck.

sun is breaking out here at the airport

I wouldn't be too concerned currently with the precip falling in SW OK as it appears to mostly be behind the front and nothing more than heavy sprinkles.

Dave you got it. :)

Few of us are now in the chat room. So feel free to join us. :)

Live Chat | Weather Spotlight (http://www.weatherspotlight.com/?page_id=40)

I don't know if they have ever upgraded to HIGH from MOD hours away from an event before, I.

I can remember a hand full of upgrades from moderate to high near the noon hour and even later.
Because so many more people have time at the lunch hour it’s always best that they get the word out to the TV Mets in time for the information to be given to a higher percentage of the public.