Severe Weather - April 16, 17, & 18 (Thur, Fri, Sat)

[venture]

Current indications are 1 to 2 rounds of severe weather this week, first will be on Thursday and the other Friday Afternoon/Evening. There may be some spill over into Saturday, but at this time it has the lowest risk out of the three days.

Update - 4/14/09 9AM: The following will be my rough outlooks. SPC outlooks will likely differ as I normally focus in on a smaller area than what their outlooks will do. I'll also keep this first post to my outlook graphics and link theirs in a later post since mine will change and theirs will vary on the date.

Thursday 4/16/2009


Storm system begins to wrap up across CO. Dryline will become established throughout the day in the TX panhandle. Current risk looks low for most of the day in Oklahoma, increase at night as storms move off the dryline and into OK. Main threat right now appears to be hail and winds, though there may be a tornado or two, especially into CO/KS. Storms that develop on Thursday may impact the OKC Metro, but more so in the period covered by the Friday outlook.

Friday 4/17/2009


Storm system continues to strengthen into Western KS. Dryline will be setup early in western OK as overnight activity is moving through this area. Some indications that we could have an on going squall line/MCS in this area in the morning that will move through Central OK during the day. Extent of severe weather will be impacted by the on going activity. If storms remain in a complex/squall line formation tornado threat will be pretty low, though wind damage may be increased some. This part of the forecast is going to be dependent on the Thursday batch, so getting too specific this far out is impractical right now.

Saturday 4/18/2009


Saturday will finally see the storm system move out. Dryline will likely be mostly dispersed by this time, but it indicated on the map to show where a boundary/area of storms is expected, in addition to back along the cold front. Again, all activity will be dependent on that of the day before. Would expect any development along the cold front to be pretty isolated, but can't rule it out right now.

Forecasts will be fine tuned and my graphics updated as we get closer. So if the text doesn't match the graphics, that would be why.

Real Time Weather Information

Satellite Image (1KM)


NEXRAD Mosaic Radar


Oklahoma Mesonet Current Conditions (red air temp, green dewpoint)

[Thunder]

Time to party!

[kevinpate]

> Current indications

Yep, all the signs are showing a lot more rain in Oklahoma County. Why just yesterday I saw another one heralding the arrival of the Festival of the Arts.

Nuttin brings rain like the arts festival, except possibly the state fair.

Bring the dawgs in and keep the umbrellas handy folks.

[venture]

Current Discussions on the Severe Threat...

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT TUE APR 14 2009

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL/SRN PLAINS...

...CNTRL/SRN PLAINS...

IT APPEARS UPPER LOW THAT WILL DIG SEWD ACROSS THE 4-CORNERS REGION WILL BE NUDGED EAST ENOUGH THAT THE CNTRL/SRN HIGH PLAINS FROM NEB...SWD INTO WEST TX WILL EXPERIENCE HEIGHT FALLS DURING THE LATTER HALF OF THE PERIOD. MODELS ARE IN GENERAL AGREEMENT THAT STRONGEST MID LEVEL FLOW WILL ROUND THE BASE OF THE UPPER LOW ALONG THE U.S./MEXICAN BORDER THEN EJECT INTO THE TX PANHANDLE AFTER 00Z. SLOW EWD PROGRESSION OF UPPER TROUGH WILL MAINTAIN SSELY LLJ ACROSS THE HIGH PLAINS WHICH WILL TRANSPORT MODIFIED BOUNDARY LAYER AIRMASS AS FAR NORTH AS SWRN NEB AND EXTREME ERN CO WHERE SFC DEW POINTS SHOULD RISE INTO THE UPPER 40S AND PERHAPS REACH 50F. FARTHER SOUTH...50S DEW POINTS WILL BE COMMON ALONG DRYLINE SWD ACROSS TX MOST OF THE PERIOD.

EARLY IN THE PERIOD IT APPEARS LOW LEVEL WARM ADVECTION WILL BE PRIMARILY RESPONSIBLE FOR SCATTERED ELEVATED CLUSTERS OF THUNDERSTORMS ACROSS PORTIONS OF WCNTRL TX...NWD INTO WRN KS. THIS ACTIVITY SHOULD NOT PROVE PARTICULARLY SIGNIFICANT AS RECOVERING AIRMASS WILL NOT BE THAT MOIST/BUOYANT. HOWEVER...WEST OF THIS WARM ADVECTION ACTIVITY STRONG HEATING WILL BE NOTED ALONG DRYLINE/FRONTAL ZONE FROM TX/NM BORDER NWD INTO ERN CO. THIS HEATING WILL PROVE INSTRUMENTAL IN DEVELOPMENT DURING THE AFTERNOON HOURS. DIURNAL ACTIVITY SHOULD INITIATE FIRST ALONG THE NRN PORTIONS OF THE FRONT ACROSS ERN CO INTO SWRN NEB. STRONG SHEAR AND JUST ENOUGH INSTABILITY ACROSS THIS REGION FAVOR NWD-MOVING SUPERCELLS THAT COULD PRODUCE ISOLATED TORNADOES IN ADDITION TO HAIL. LATE IN THE AFTERNOON CONVECTIVE TEMPERATURES WILL BE REACHED ACROSS THE TX PANHANDLE...THOUGH LOW LEVEL CONVERGENCE MAY BE SOMEWHAT WEAKER...INITIALLY...ALONG SRN BOUNDARY UNTIL LATER IN THE OVERNIGHT HOURS. ISOLATED SUPERCELLS MAY DEVELOP ACROSS THIS REGION THEN EVOLVE INTO LARGER THUNDERSTORM CLUSTERS OR AN MCS AS LLJ INTENSIFIES AFTER DARK. THIS CONVECTIVE COMPLEX SHOULD PROPAGATE EWD ACROSS THE SRN PLAINS...OVERSPREADING MUCH OF WRN OK/NWRN TX BY 12Z.

====

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0340 AM CDT TUE APR 14 2009

VALID 171200Z - 221200Z

...DISCUSSION...

SLOW MOVING UPPER LOW WILL GRADUALLY SHIFT INTO THE PLAINS DURING THE DAY4-6 TIME FRAME...PRIMARILY DUE TO A STUBBORN UPPER RIDGE THAT FINALLY BREAKS DOWN OVER THE MS/OH VALLEY REGION LATE. SLOW MOVING NATURE OF THIS UPPER SYSTEM WILL RESULT IN LESS PREDICTABILITY REGARDING TIMING OF SEVERE THUNDERSTORM DEVELOPMENT...AS CLUSTERS OF THUNDERSTORMS AND MCS/S WILL LIKELY EVOLVE THROUGHOUT THE PERIOD...PROPAGATING ACROSS MORE BUOYANT REGIONS EFFECTIVELY OVERTURNING LARGE AREAS OF INSTABILITY. EVEN SO IT APPEARS ENOUGH MOISTURE/INSTABILITY WILL OVERSPREAD MUCH OF THE SCNTRL U.S. AHEAD OF UPPER TROUGH TO WARRANT A RISK OF SEVERE FRIDAY INTO SATURDAY. SEVERE THUNDERSTORMS ARE POSSIBLE BEYOND THE DAY5 PERIOD ACROSS THE CNTRL GULF STATES AS UPPER TROUGH SHIFTS EAST BUT DUE TO THE AFOREMENTIONED PROBLEMS WITH CONVECTION/INSTABILITY WILL HOLD OFF SPREADING OUTLOOK DOWNSTREAM FOR NOW.

====

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
337 AM CDT TUE APR 14 2009

.DISCUSSION...
AFTER A COUPLE OF COOL... SOGGY DAYS WE WILL GET A COUPLE OF WARM AND DRY DAYS BEFORE THE NEXT STORM SYSTEM BRINGS RAIN BACK INTO THE FORECAST. SUNNY SKIES... MILDER TEMPS AND SOUTH WINDS RETURNING WILL DESCRIBE TODAYS WX ACROSS THE SOUTHERN PLAINS AS NEXT STORM SYSTEM DROPS SOUTH INTO CALIFORNIA. WEDNESDAY WILL SEE SOUTH WINDS INCREASE
IN RESPONSE TO PRES FALLS IN LEE OF ROCKIES AS LARGE UPPER LOW CLOSES OFF OVER INTERMOUNTAIN WEST. THIS LOW WILL THEN MOVE SLOWLY EAST TOWARD THE SOUTHERN PLAINS THROUGH THE END OF THE WEEK.

ALTHOUGH WE COULD SEE A FEW STORMS DEVELOP ACROSS FAR WESTERN OK LATE WED/WED NIGHT BETTER CHANCES WILL OCCUR ON THU AS SYSTEM INCHES CLOSER AND BETTER MOISTURE BEGINS TO RETURN NORTH OUT OF THE GULF. WILL LIKELY SEE STORMS DEVELOP THU AFTN ALONG DRY LINE WHICH WILL SET UP ACROSS THE EASTERN TX/OK PANHANDLES. A FEW OF THESE STORMS COULD BE OF THE SEVERE VARIETY... HOWEVER MODELS ARE TRENDING TOWARD SLIGHTLY LESS IMPRESSIVE SURFACE MOISTURE RETURN AND ARE KEEPING WIDESPREAD LOW CLOUDS ACROSS MUCH OF THE AREA THROUGHOUT THE DAY ON THU. THIS MAY LIMIT INSTABILITY AND SEVERE POTENTIAL. HOWEVER... MODELS THEN ARE SHOWING SOME INTERESTING SIGNS FOR THU NIGHT INTO FRI AS BOTH THE GFS AND ECMWF ROTATE A LOBE OF ENERGY AROUND UPPER LOW... WHICH DEVELOPS A LARGE AREA OF SHOWERS/THUNDERSTORMS OVERNIGHT THU NIGHT/EARLY FRI ALONG WITH THE AID OF STRONG LLJ.

THIS MAY SET UP AN EVENT MUCH LIKE WHAT OCCURRED LAST SUNDAY WITH A MORE WIDESPREAD RAIN EVENT FOR FRIDAY... WITH SEVERE RISK SOMEWHAT LIMITED. STILL QUITE A BIT OF UNCERTAINTY WITH HOW THINGS WILL UNFOLD BOTH THU AND FRI. MODELS THEN LIFT UPPER LOW OUT ON SATURDAY WITH SURFACE COLD FRONT BRINGING YET ANOTHER COOL CANADIAN AIRMASS
INTO THE SOUTHERN PLAINS SATURDAY NIGHT AND SUNDAY.

MAIN CHANGES WILL BE TO CONT THE TREND OF INCREASING PRECIP CHANCES IN THE LATE THU INTO FRIDAY TIMEFRAME AND TO COOL DAYTIME TEMPS DOWN SOME WITH EXPECTED PRECIP AND CLOUD COVER.

[Charlie40]

Moisture return with this next system is not going to be as robust as first thinking, also another limiting factor for widespread severe weather will be cloud cover left over from overnight rains. While we may see a few marginally severe to severe thunderstorms, I don't think this will be by any means a widespread severe outbreak event. Things always can change but asx of right now thats what we are looking at. Also the possibility of flooding rains.

[venture]

Moisture return with this next system is not going to be as robust as first thinking, also another limiting factor for widespread severe weather will be cloud cover left over from overnight rains. While we may see a few marginally severe to severe thunderstorms, I don't think this will be by any means a widespread severe outbreak event. Things always can change but asx of right now thats what we are looking at. Also the possibility of flooding rains.

Pretty much. Thursday will help define how the rest of the period will go.

[westsidesooner]

This system looks very similar to the one that came through last weekend. I'm expecting a lot of rain and maybe some good hailers...depending on how cool the air with the next low is. Maybe if we get lucky we'll at least get a good cold core setup if the low tracks close enough.....any ideas on the track yet?

[venture]

I think we all have the forecast pretty well handled - lots of rain, some hailers, no fires this weekend. LOL New MCD on the ongoing activity is out.



MESOSCALE DISCUSSION 0481
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT THU APR 16 2009

AREAS AFFECTED...PORTIONS NW TX...ERN/NRN TX PANHANDLE...CENTRAL/ERN OK PANHANDLE...WRN OK...WRN KS...EXTREME ERN CO.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 161620Z - 161815Z

POTENTIAL IS INCREASING FOR ISOLATED TO WIDELY SCATTERED AND MARGINAL SVR HAIL...WITHIN GROWING PLUME OF CONVECTION NOW EVIDENT FROM SW OK ACROSS NERN TX PANHANDLE TO VICINITY KS/CO BORDER. WHILE THIS ACTIVITY MOVES N WITH GRADUAL INTENSIFICATION...SOME BACKBUILDING/FILLING ALSO IS POSSIBLE ACROSS PORTIONS NW TX AND
CENTRAL/NRN PANHANDLE. THIS IS SEPARATE FROM MID-LATE AFTERNOON/SFC-BASED SVR THREAT DISCUSSED IN DAY-1 OUTLOOK...AND IS NOT EXPECTED TO BE AS WELL-ORGANIZED.

12Z UPPER AIR ANALYZES AND RUC GUIDANCE INDICATE INCREASING LOW LEVEL MOISTURE -- ESPECIALLY IN 925-850 MB LAYER -- ASSOCIATED WITH BROAD/40-50KT SSELY LLJ. MAX MOISTURE TRANSPORT SHOULD CONTINUE ACROSS THIS REGION...PERHAPS SHIFTING SLIGHTLY WWD AS PANHANDLES/SWRN KS/SERN CO SEGMENT OF LLJ BACKS AND INTENSIFIES SOMEWHAT THROUGH EARLY AFTERNOON. THIS REGIME GRADUALLY WILL BECOME INCREASINGLY JUXTAPOSED WITH ERN EDGE OF MORE ROBUST LARGE-SCALE ASCENT AND COOLING ALOFT AS CENTER OF BROAD UPPER CYCLONE PIVOTS EWD THROUGH 4-CORNERS AREA. MODIFIED 12Z RAOBS AND RUC SOUNDINGS INDICATE ELEVATED MUCAPE IN 1000-1500 J/KG RANGE. PRIMARY LIMITING FACTOR APPEARS TO BE LACK OF MORE ROBUST SHEAR FOR ELEVATED LIFTED PARCELS. WITH STRONGEST DEEP-LAYER WINDS REMAINING W OF THIS AREA AT LEAST UNTIL EARLY-MID AFTERNOON...FCST SOUNDINGS SHOW ONLY SMALL HANGES WITH HEIGHT IN DIRECTION/SPEED OF FLOW THROUGH INFLOW-BUOYANT LAYERS. THIS SHOULD KEEP EFFECTIVE SHEAR MAGNITUDES BELOW 30 KT IN MOST OF DISCUSSION AREA UNTIL INFLOW PARCELS BECOME SFC-BASED...LIKELY AROUND MID-AFTERNOON NEAR W EDGE OF THIS CLOUD/PRECIP AREA WHERE HEATING IS STRONGER. KINEMATIC GEOMETRY ALSO SHOULD CONTRIBUTE TOWARD MIXTURE OF MULTICELL CLUSTERS AND LINEAR MODAL TENDENCIES.

..EDWARDS.. 04/16/2009

[ultimatesooner]

sweet

bring on some nados

[westsidesooner]

sweet

bring on some nados

If you wanna see a tornado today you'll have to drive to the caprock. I've been watching the chasers online and they had a really good wall clouds a few minutes ago, and so much hail they are having to use snowplows to clear the highways. Wish I was there...

[Thunder]

Well, another storm season bust. I guess it'll be a few weeks before the actions get more interesting.

[venture]

Few things going on. One is the MCS in SE Oklahoma and Texas. This pretty much has stabilized a lot of the atmosphere around us. There is still some instability back west near the dryline that could kick off some storms later today out there (say around 7PM). Look for rain/storms to fill in some tonight and come over us throughout the night. Tomorrow, upper/mid air dryslot gets in will help clear things out. Front and dryline will be west still tomorrow, and clear skies and remaining moisture should allow for the development of some isolated/scattered severe storms.

Best risk tomorrow is North central Oklahoma and to the east. Though the rest of the area is will within the risk area for some hailers and strong winds.

[westsidesooner]

Well, another storm season bust. I guess it'll be a few weeks before the actions get more interesting.

Being Mr. Pessemistic today? Don't worry, the storm season hasn't even gotten to the half way point. Statistical peak is usually early May around the 3rd...go figure. But you're right it has gotten off to a slooooow start.
____
Venture, what are you're thoughts on the possibilities of a few funnels or small tornadoes tomorrow? I don't know if it would be a classic cold core set up, but watching the vis. sat today I really like the clearing and the lift around the low back west. Anything that does develop tomorrow should be fairly low topped. Boring I know, but sometimes make for some unexpected funnels. If we can get some sun tomorrow who knows. Of course that all depends on the timing and track of the low.

[Of Sound Mind]

Some of us don't mind a slow and uneventful storm season... in fact we prefer it if for no other reason than pure selfishness about safety of life, limb and property.

But I can understand why storm chasers would be disappointed.

[Luke]

Yeah, I'm with you, Brad. The longing desire for tornadoes and hail is beyond me...

[Bunty]

Surely such people don't have a vegetable garden. After you have worked hard to get one established you sure don't want a ground covering hail storm to destroy it.

[westsidesooner]

Some of us don't mind a slow and uneventful storm season... in fact we prefer it if for no other reason than pure selfishness about safety of life, limb and property.

But I can understand why storm chasers would be disappointed.

Its hard to imagine I guess. Why some people are fascinated by storms. I think my love for them grew from fear, then respect. When I was a child I was terrified by a close encounter with a tornado, then decided the best way to overcome my fear was to understand what was causing it. So I started paying attention to the weather, and studying it. Then I became fascinated by the power and the beauty of storms. Plus storm chasing/spotting let me enjoy some of my favorite interests (travel, photography, nature, science, geography, comradery) Nature at its best (and worst). That said I still get nervous when storms threaten my home or loved ones, But I know what Im up against now, and they rarely catch me off guard. No one likes to see damgae and injuries...especially stormchasers....most of them are there to warn the public.

BTW new MCD out for western Oklahoma Storm Prediction Center Mesoscale Discussion 503

[westsidesooner]

Surely such people don't have a vegetable garden. After you have worked hard to get one established you sure don't want a ground covering hail storm to destroy it.

LOL..you caught me between posts. Such people do have gardens. I do. Every year there is grass seed to get washed away (my current project) and plants to be protected. We have alot of potted plants and glass lanterns in our yard. And a very heavy, very valuable old chiminea. Everytime I bring everything in prior to a storm my friends say Im jinxing the storm and it misses us.

Its nature...you roll with the punches.

[venture]

Westside is pretty much has the same background I do. At age 11-ish...I watched a rope tornado pass by the house by a half mile. I've never, even tho this say, seen a tornado whip around like that did. The image of a snake being held by the head and tail with the body in between whipping around back and forth. Definitely something to scar a kid. Now? I've done my studying, went to school for it, etc...understand how/why things happen. Nearly every storm chaser has a huge amount of respect for Mom Nature and when she gets grumpy. Most of us stay out of the way, alert the appropriate people on whats going on, and use the experiences to educate ourselves further. I say most, because there are plenty out there just for the thrill of things and couldn't care less about anything else.

Anyways...tomorrow. Cold core setup definitely has my interest and might be something to watch.

[Thunder]

There is someone by the name of Zack that is into weather. I think it would be great if he is aware of OKCTalk and join us. Both him and Venture can provide us valuable info.

Here is a comment quote from him.

Tomorrow while the rain chances will decrease as the dry slot works its way into the southern plains, the threat for severe weather will actually increase over much of central, northern, and eastern Oklahoma. Depending on how convection plays overnight there could be some scattered severe storms over the state tomorrow. A dynamic and large cold pool aloft with steep lapse rates favor large hail over north central Oklahoma, further south and west along the dry line that redevelops to the west tomorrow the potential is there for low topped supercell thunderstorms. Wind fields in this region are relatively weak, however deepening LL moisture across the area and strong instability given diurnal daytime heating will allow for any storm that manages to develop to become severe with large hail and damaging winds. A few tornadoes may occur near any interacting boundaries left by storms tomorrow afternoon, though widespread significant severe weather is unlikely given somewhat weaker wind fields tomorrow.

KOCO's weather blog.

Weather Blog

They have somewhat upgraded the risk slightly. A slight chance of isolated tornadoes is in the forecast, but sizeable hails is more likely.





We should all definately be weather aware on Saturday. Hail itself is enough to cause serious injury. I remember it was last year that MWC had seen quite a bit of people being injured by hails, so the storms seem likely to be a hail producer.

Remember the slight risk we had back on May 3rd '99, well anything is possible for Saturday now that the forecast is calling for isolated tornadoes potential. It all depends on how the setup overnight with the dry slot and the convection.

If I'm correct, I think the dry slot clears up the sky and allow more heat and instability. Correct, Venture? Does the summer dry slot affect the moisture/dew point as it does for winter storm?

[venture]

Dryslots are typically more of a mid to upper level feature. Like tomorrow in the afternoon...most of the area up the I-44 corridor and about 100 miles on each side will be pretty dry. Though at the service dewpoints may still be in the 50s. Tomorrow definitely won't be a major severe weather day by any shot. Low level moisture will be relatively poor. Some model indication shows isolated storms forming tomorrow in western Oklahoma moving east starting around 5PM with all chances out of OKC by 10PM. Highest weak tornado potential will be along the Kansas border under the low.

We'll probably see some hailers tomorrow but maybe not more. I would probably start looking towards next week for a real shot at severe weather - at least going by current model indications.

[Thunder]

After this, shouldn't we be expecting a long stretch of dry weather?

[Thunder]

[venture]

After this, shouldn't we be expecting a long stretch of dry weather?

Looks like a week until the next system rolls in.

As for today, hail risk has been increased with a hatched area by SPC over most of Central and Western Oklahoma. Short range models seem to be in decent agreement today develop isolated/scattered activity mostly after 1PM in the west. Timing seems a bit slower than last night, with activity in Central OK after 8PM til about midnight.

NSSL Realtime WRF model Forecasts

http://www.emc.ncep.noaa.gov/mmb/mpy..._1000m_f24.gif

Tornado threat today is pretty nil, except (as stated yesterday) up along the KS border by the low.

[Thunder]

Yeah, I'm not expecting a tornado today. The sky still have not clear up yet.

A partial quote from KOCO's Andy.

On a day like this, we say “there are going to be a lot of hailers”. It’s not out of the question to see a tornado/cold air funnel (I get nervous separating them because I don’t want you to see one and actually consider not taking shelter–you need to take shelter). Storms will be most numerous from mid-afternoon through the evening.

I still will not expect a tornado, but I could be wrong. LOL