Oklahoma Severe Weather Discussion - May 2011

[bandnerd]

So sorry to disappoint Uncle and Thunder (not). There was a little wind damage in places but no houses destroyed or people killed. It was almost a best case scenario with a lot of welcome rain.

We need a like button here so I could "like" this. Even though it made driving on the highway a bit dicey around 4pm going toward Edmond, and there was some spectacular lightning along the way, I would rather have to squint to see in the rain than hide in my laundry room.

[Thunder]

I laughed when David said on his chat, something like, "Poor dryline did not stand a chance.." and it was like the dryline saying, "WTF?!" :-O

Everything turned out so wrong yesterday. All the chasers and weather people...a total bust for "tornadoes outbreak" but such a welcoming for rain. It was funny, one of Mike's graphics was saying, "Not a wall of waters..." Well, most of us ended up getting much more than a wall of waters. :-)

When it rains, it pours! And for Oklahoma City, today’s heavy rain is just what we needed! Why? Becuase, this is the wettest month of the entire year and if we don’t get the rain now, then we’re up a creek. So, for the books, it’ll go down as 1.34 inches of rain received on this date, making it the biggest rainfall day that we have seen since September 12th.

-Damon

PS- Sorry Western Oklahoma…

http://kocoweatherblog.wordpress.com/

I am sure western portions received plenty of rain. We will have to wait on the rain totals to be posted.

Btw, the rain report for OKC is based at the airport. Other areas probably received much more.

My flowers is dancing out there now! :-O

[venture]

This is a pretty good estimate on how much rain we got yesterday. I used the 4-day graphic so the totals don't vanish for a couple of days from this map.



Still very rough in far SW and the Panhandle...

[venture]

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 293
NWS STORM PREDICTION CENTER NORMAN OK
320 PM CDT THU MAY 12 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

WESTERN ARKANSAS
EXTREME SOUTHEASTERN KANSAS
SOUTHWESTERN MISSOURI
EASTERN OKLAHOMA
EXTREME NORTH CENTRAL TEXAS

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 320 PM UNTIL
1000 PM CDT.

WIDELY SCATTERED DAMAGING WINDS
ISOLATED WIND GUSTS TO 70 MPH POSSIBLE
SCATTERED LARGE HAIL TO 2.5 INCHES IN DIAMETER
ISOLATED TORNADOES

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95
STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH
NORTHEAST OF SPRINGFIELD MISSOURI TO 25 MILES SOUTH SOUTHEAST OF
SHERMAN TEXAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 290...WW 291...WW 292...

DISCUSSION...STORMS ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF EWD
ADVANCING PACIFIC FRONT WHERE THE ATMOSPHERE HAS BECOME MODERATELY
UNSTABLE WITH 2000-2500 J/KG MLCAPE. DESPITE SMALL LOW LEVEL
HODOGRAPHS...EFFECTIVE SHEAR IS SUPPORTIVE OF SUPERCELLS WITH LARGE
HAIL AND DAMAGING WIND THE MAIN THREATS. A FEW STORMS COULD ALSO
EVOLVE INTO BOWING LINE SEGMENTS WITH TIME.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 24035.

[PennyQuilts]

My digital rain gauge said 1.18 inches but the old fashioned one was filled just over 1.5 inches.

[venture]

So it is that time again to take a look through the unreliable and foggy forecast window to see what may be coming our way. For this trip we’ll be using the 00Z GFS. Naturally all longer range dates on the GFS (some short range too) need to be taken with a gallon of salt as it is pretty volatile in its solutions.

Saturday May 14 to Tuesday May 17th
We are looking mostly dry through this period. No major amounts of precip showing up. Should be a decent period to let whatever moisture we got this past week finish soaking in and really letting the grass go wild. Finally. For those that didn’t get any here recently, sorry…more of the same. However, fire danger appears to be staying out of the Very High and Extreme categories – so that’s good, but not great for the wheat crop that needs moisture.

After this period, it looks like storm season could ramp up a bit.

Saturday May 14 to Tuesday May 17th
We are looking mostly dry through this period. No major amounts of precip showing up. Should be a decent period to let whatever moisture we got this past week finish soaking in and really letting the grass go wild. Finally. For those that didn’t get any here recently, sorry…more of the same. However, fire danger appears to be staying out of the Very High and Extreme categories – so that’s good, but not great for the wheat crop that needs moisture.

Wednesday May 18th
The deep trough we were seeing form behind the system we just had will start to move out into the plains. The ridge will be breaking down Monday & Tuesday and the first batch of energy starts to move in Wednesday morning…early. Looks like a general area of showers and a couple storms will spread over the start, increasing in coverage through the day. Amounts look like, but really shouldn’t worry about that this far out. Instability isn’t looking to be crazy at all, so this might just be a very low key chance of rain across the state.

Thursday May 19th
Dryline should be formed up pretty well after the activity on Wednesday and will move through roughly the western 1/3rd of OK during the daylight hours on Thursday. Moisture will continue to pump in with dewpoints in mostly the mid 60s to near 70 in the south. Instability will be rising as well and we should have a decent amount around, but nothing high end. 500 mb winds are extremely strong should the main trough moving through OK with winds 60 to 75 kts. Surface to 500mb shear looks pretty good, but the strong winds over 700 mb could leave us with a lot of leaning towers and not much upward development. Severe day? Maybe…but as I have stated 83 times already, way too early to say. Considering how well the May 11th activity shaped up and how well the models handled that day, nothing is written in stone. We’ll just put it down as a “one to watch” day. Which really means very little.

Friday May 20th
Looks like the system will be wrapping up pretty good in the Central Plains. The surface low looks like it will move almost northerly as it just wraps up. Instability forecast is somewhat misleading showing some decent values over the eastern half of the state, but very little precip. Not really expecting much in Oklahoma, except early morning storms racing east, but the model kinda hints at some sort of low in OK that could be wrapping some precip back into the state…or at least some type of feature. Not sure, but something just sticks out a bit that I want to see how this day evolves. May be nothing, or it may just be that stupid “Friday” song stuck in my head as I write this.

Saturday May 21st
The dreaded “along and east of I-35″ line has to be used here. Looks like most rain/storm chances will be eastern 1/2 of Oklahoma. We’ll probably have a boundary or front of some sort in the state at the time. Dryline doesn’t look all that well defined this far out. Instability is definitely there, so another day that is a one to watch.

For the period following the 21st, you can read the full outlook on my blog on Storm-Scope.com at: http://www.storm-scope.com/blog/?p=46

[venture]

GFS and NAM aren't too far apart this evening, but they only go out together until Thursday. After that is it mostly GFS and what little ECMWF data we have. Had outlook maps all made up, but the mapper software apparently wasn't saving them when I thought it was. So they are gone. LOL Needless to say the forecast is pretty simple, but each day's activity can impact the next. Basically we are looking at an extended period of unsettled weather (YAY RAIN!). Look for it to start on Wednesday and last until the middle of next week. Main threat area for strong storms will be ahead of the dryline which will be dancing back and forth mainly well west of I-35. Each day start Thursday looks like a chance for a storm to reach severe levels. Not every day will have severe storms. Just like some days may have an enhanced risk of severe weather (Sunday).

As we get closer I'll start getting more details in outlooks and such. Remember you can follow the updates here but also on http://www.storm-scope.com where I'll go a bit more indepth and continue to post updated links to great resources.

[venture]

New blog post is up that goes into the upcoming outlook for severe weather through this week and most of next.

http://www.storm-scope.com/blog/?p=50

Sunday continues to look interesting.

[venture]

The Storm Prediction Center has put out their new Day 3 and Day 4-8 Outlooks and have included most of Oklahoma in a risk for severe weather. Much like discussed earlier this morning, the severe threat is going to be on the increase. They have trended much slower with the system for Friday, and have the risk area more to the west than I did in mine last night. As always, I would take their outlooks more seriously than mine.

Details today in the blog: http://www.storm-scope.com/blog/?p=52

[Thunder]

I bookmarked your new site. I kinda gave up for any exciting Tornado season for this year, so I haven't kept track since our last major bust, although we did receive really nice rain.

Two reasons I really like tornadoes, they are awesome when watching them form and they are awesome to clean up the cities. Although financial, property, and life losses are really bad/sad, which I hate, but always look at the positive side of Mother Nature helping to clean up when our city leaders, business owners, land owners, and landlords failing to do so.

[venture]

I bookmarked your new site. I kinda gave up for any exciting Tornado season for this year, so I haven't kept track since our last major bust, although we did receive really nice rain.

Thanks for the follow. Not sure how much more exciting you want it. We set a record for most tornadoes ever in the month of April with 47. We are sitting at 48 overall with a seasonal average around 54. May is our historical peak and it looks like a busy end of this week and next right now. June still averages 8 in the state then quieting down for the rest of year with around 2 tornadoes a month. October can get busy again, so we'll wait until then.

Slight Risk is up for west of I-35 tomorrow. Roughly the same area on Thursday. Friday should move out across most of Central & Eastern OK. Sunday is still looking like a potential big day if we don't run into the issue of left over morning convection. Then also risk is there Monday, Tuesday, Weds (mainly SE OK), Thursday, and Friday...yeah - welcome to Spring.

[tornado74]

Venture - what do you think of Friday's setup? It's looking like a potential bust with morning convection the culprit once again.

[venture]

Venture - what do you think of Friday's setup? It's looking like a potential bust with morning convection the culprit once again.

I'm looking at it this way. There is going to be a risk of severe weather, somewhere in the state, through next week. There will always be the risk of morning convection being around to complicate the forecast. The best thing to do is just go day by day because not everyday is going to work out, but also because any left over boundaries are going to change how things actually occur regardless of what the models say.

[venture]

The slight risk area for today has been shifted east drastically. It now includes the entire OKC metro area.

I will be bringing the chat room up shortly and getting the live cam and such going again on http://www.storm-scope.com.

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1131 AM CDT WED MAY 18 2011

VALID 181630Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE CNTRL AND
SRN HIGH PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER OH
VALLEY INTO MID ATLANTIC STATES...

...CNTRL/SRN PLAINS...

POTENT VORTICITY MAXIMUM AND ASSOCIATED MID AND HIGH-LEVEL JET
STREAKS DIGGING SEWD INTO THE LOWER CO VALLEY WILL ROUND LARGE-SCALE
TROUGH BASE TODAY...REACHING THE CNTRL/SRN HIGH PLAINS BY 19/12Z.
THERE IS SOME INDICATION THAT A WEAKER LEAD IMPULSE MAY BE LOCATED
NEAR THE FOUR CORNERS REGION WHICH WOULD TRANSLATE NEWD INTO THE
CNTRL HIGH PLAINS THIS EVENING. IN THE LOW LEVELS...SURFACE CYCLONE
OVER W-CNTRL OK AS OF MID MORNING WILL BECOME MORE ELONGATED WITH
TIME AS PRESSURE CONTINUES TO FALL OVER THE SRN HIGH PLAINS.
DRYLINE WILL MIX EWD AND WILL LIKELY EXTEND FROM INTERSECTION WITH
WARM FRONT OVER NWRN OK SEWD TO JUST W OF THE OKC AREA AND THEN SWWD
INTO W-CNTRL TX BY LATE AFTERNOON.

SLY LOW-LEVEL FLOW E OF DRYLINE WILL SUPPORT THE NWD FLUX OF AN
INCREASINGLY MOIST BOUNDARY LAYER TODAY WITH DEWPOINTS RISING INTO
THE LOWER/MID 60S. THIS MOISTURE COUPLED WITH DAYTIME HEATING AND
MODESTLY STEEP MIDLEVEL LAPSE RATES WILL YIELD A MODERATELY UNSTABLE
AIR MASS BY AFTERNOON WITH MLCAPE VALUES APPROACHING 2000-2500 J/KG.
LATEST MESOSCALE AND CONVECTION-ALLOWING MODEL GUIDANCE REMAIN
CONSISTENT IN SUGGESTING THAT THE COMBINATION OF STRONG DIABATIC
HEATING W OF DRYLINE AND POTENTIAL INFLUENCE OF ABOVE-MENTIONED LEAD
IMPULSE WILL CONTRIBUTE TO ISOLATED STORM DEVELOPMENT LATER TODAY.
GIVEN FORECAST VERTICALLY VEERING WIND PROFILES WITH 40-50 KT OF
DEEP WLY SHEAR AND 0-1 KM SRH OF 100-200 M2/S2...SETUP WILL FAVOR
SUPERCELL DEVELOPMENT WITH ATTENDANT RISKS FOR VERY LARGE HAIL...A
COUPLE TORNADOES AND LOCALLY DAMAGING WINDS.

ELSEWHERE...A CONDITIONAL THREAT FOR ISOLATED SEVERE STORMS WILL
EXIST ALONG BENT-BACK SEGMENT OF WARM FRONT EXTENDING FROM NWRN OK
INTO ERN CO THIS AFTERNOON INTO TONIGHT. HERE TOO...KINEMATIC
ENVIRONMENT WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF LARGE HAIL
AND PERHAPS A TORNADO.

[SoonerDave]

Judging from the way this deck of cumulus seems to be thickening in the PM heating, and the fact that the humidity really seems to be going up, can't help but wonder if we might not see some storms here in central OK in the next few hours...

[Jesseda]

a lot of storm trackers are heading towards central part of oklahoma right now, i wonder if they know something ?

[tornado74]

I'm looking at it this way. There is going to be a risk of severe weather, somewhere in the state, through next week. There will always be the risk of morning convection being around to complicate the forecast. The best thing to do is just go day by day because not everyday is going to work out, but also because any left over boundaries are going to change how things actually occur regardless of what the models say.

Good advice Venture. It's easy for me to get too excited or too down on a forecast that is Day 2 or further out. We'll just have to wait and see. Today didn't like it was going to be much a few days ago, and now it's looking better and better.

[PennyQuilts]

Judging from the way this deck of cumulus seems to be thickening in the PM heating, and the fact that the humidity really seems to be going up, can't help but wonder if we might not see some storms here in central OK in the next few hours...

Yeah, it really feels like it is starting to simmer and get punchy.

[Thunder]

I was not aware of anything for today. I thought something for Sunday. :-/

This is funny chit, cuz I was just out there at Lowes on I-240 and now I come home to see slight risk and supercells potential. It brings back the good ole memories of May 3rd.

[ou48A]

Yeah, it really feels like it is starting to simmer and get punchy.

+1
In the last 2 or so hours we are gradually starting to see more sun here in Norman

[venture]

MESOSCALE DISCUSSION 0804
NWS STORM PREDICTION CENTER NORMAN OK
0244 PM CDT WED MAY 18 2011

AREAS AFFECTED...WRN/CNTRL OK...PORTIONS OF N TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 181944Z - 182045Z

THE POTENTIAL FOR CONVECTIVE INITIATION APPEARS TO BE INCREASING
THIS AFTERNOON ACROSS WRN OK AND PORTIONS OF N TX...ALTHOUGH SOME
UNCERTAINTY STILL REMAINS. THE ENVIRONMENT WILL BE FAVORABLE FOR
ISOLATED SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL AND
POSSIBLY TORNADOES. THE AREA IS BEING MONITORED FOR A POSSIBLE WW.

STRONG DIABATIC HEATING ACROSS WRN OK HAS RESULTED IN AN EWD
ADVANCEMENT OF A SFC DRYLINE...POSITIONED FROM 40 SSW SPS TO FSI TO
40 NE CSM /PER 19Z SUBJECTIVE ANALYSIS/. THIS FEATURE IS ATTENDANT
TO A DEEPENING SFC LOW...AND A DIFFUSE BAROCLINIC ZONE/WARM FRONT
PROTRUDING ESE ACROSS CNTRL AND SERN OK. THERE IS SOME UNCERTAINTY
REGARDING CONVECTIVE INITIATION AS RECENT SFC OBSERVATIONS HAVE
INDICATED WINDS IN THE POST-DRYLINE ENVIRONMENT HAVE BACKED TOWARDS
THE S /LIMITING LOW-LEVEL CONVERGENCE/. THIS MAY BE OFFSET BY AN
AREA OF IMPLIED ASCENT THAT APPEARS TO BE SPREADING EWD OUT OF THE
SRN HIGH PLAINS...WHERE A BROAD SWATH OF CIRRUS HAS DEVELOPED IN
RECENT VISIBLE SATELLITE/WATER VAPOR IMAGES. AS THIS APPROACHES WRN
OK AND NW TX...WEAKENING CINH AND INCREASING MID-LEVEL ASCENT SHOULD
LEAD TO A MORE FAVORABLE ENVIRONMENT FOR CONVECTIVE INITIATION THIS
AFTERNOON.

RICH BOUNDARY LAYER MOISTURE AHEAD OF THE DRYLINE /LOWER-MID 60S SFC
DEW POINTS/ ALONG WITH STEEP MIDLEVEL LAPSE RATES IN EXCESS OF 7 DEG
C PER KM HAS YIELDED MLCAPE VALUES OF 1500-2000 J/KG...WHICH WILL
SUPPORT A THREAT FOR VERY LARGE HAIL. ADDITIONALLY...ENHANCED
LOW-LEVEL WIND SHEAR RESULTING FROM BACKED FLOW /PARTICULARLY WITH
NWD EXTENT/...ALONG WITH A FAVORED DISCRETE CONVECTIVE MODE DUE TO A
SIGNIFICANT ORTHOGONAL COMPONENT OF THE EFFECTIVE SHEAR VECTOR
RELATIVE TO THE DRYLINE...SHOULD SUPPORT A THREAT FOR TORNADOES IF
LONG-LIVED SUPERCELLS CAN DEVELOP. HOWEVER...CLOUD COVER ACROSS
CNTRL OK HAS LIMITED HEATING/INSTABILITY PRIMARILY E OF I-35...WITH
SOME QUESTION REGARDING MAINTENANCE OF THUNDERSTORMS MOVING E OFF
THE DRYLINE.

..ROGERS.. 05/18/2011

[ou48A]

Tornado Watch

TORNADO WATCH OUTLINE UPDATE FOR WT 306
NWS STORM PREDICTION CENTER NORMAN OK
350 PM CDT WED MAY 18 2011

TORNADO WATCH 306 IS IN EFFECT UNTIL 1100 PM CDT FOR THE
FOLLOWING LOCATIONS

OKC003-011-015-017-019-027-031-033-039-043-045-047-049-051-053-
059-067-073-075-083-085-087-093-099-109-137-141-149-151-153-
190400-
/O.NEW.KWNS.TO.A.0306.110518T2050Z-110519T0400Z/

OK
. OKLAHOMA COUNTIES INCLUDED ARE

ALFALFA BLAINE CADDO
CANADIAN CARTER CLEVELAND
COMANCHE COTTON CUSTER
DEWEY ELLIS GARFIELD
GARVIN GRADY GRANT
HARPER JEFFERSON KINGFISHER
KIOWA LOGAN LOVE
MAJOR MCCLAIN MURRAY
OKLAHOMA STEPHENS TILLMAN
WA****A WOODS WOODWARD

[silvergrove]

WA****A

I know there's a language filter and all but this is always so amusing to me. It feels rather warm today.

[venture]

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 306
NWS STORM PREDICTION CENTER NORMAN OK
350 PM CDT WED MAY 18 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

WESTERN AND CENTRAL OKLAHOMA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 350 PM UNTIL
1100 PM CDT.

SEVERAL TORNADOES
WIDELY SCATTERED DAMAGING WINDS
ISOLATED WIND GUSTS TO 70 MPH POSSIBLE
SCATTERED LARGE HAIL
HAIL TO 2.5 INCHES IN DIAMETER LIKELY

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTHEAST OF FORT
SILL OKLAHOMA TO 15 MILES NORTH NORTHWEST OF ALVA OKLAHOMA. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU6).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 305...

DISCUSSION...ISOLATED STORM DEVELOPMENT IS ANTICIPATED WITHIN THE
NEXT ONE TO TWO HOURS ALONG DRYLINE WHICH HAS BECOME STATIONARY OVER
WRN OK. AIR MASS E OF DRYLINE IS CHARACTERIZED BY DEWPOINTS IN THE
LOW/MID 60S...WHICH WHEN COUPLED WITH MIDLEVEL LAPSE RATES OF AROUND
7 C/KM...IS RESULTING IN A MODERATELY UNSTABLE AND WEAKLY CAPPED
ENVIRONMENT WITH MLCAPE AROUND 2000 J/KG. PROFILER DATA ACROSS ERN
NM SUGGEST THAT CIRRUS PLUME SPREADING EWD ACROSS WRN TX INTO WRN OK
IS ASSOCIATED WITH A 50 KT MIDLEVEL JET STREAK WHICH WILL SERVE TO
STRENGTHEN DEEP-LAYER SHEAR THROUGH THIS EVENING. LOW-LEVEL SHEAR
SHOULD ALSO INCREASE AROUND OR SHORTLY AFTER 19/00Z WITH VERTICAL
WIND PROFILES BECOMING QUITE CONDUCIVE FOR SUPERCELL DEVELOPMENT.
VERY LARGE HAIL WILL BE THE PRIMARY HAZARD...THOUGH TORNADOES WILL
BE POSSIBLE WITH ANY MATURE SUPERCELLS THAT CAN PERSIST INTO THIS
EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24025.

[venture]

Acus01 kwns 190522
swody1
spc ac 190520

day 1 convective outlook
nws storm prediction center norman ok
1220 am cdt thu may 19 2011

valid 191200z - 201200z

...there is a slgt risk of svr tstms over a portion of the srn and cntrl plains...

...synopsis...

Blocking pattern will persist into thursday with closed upper lows over the intermountain west and oh valley drifting only very slowly east. A series of vorticity maxima will rotate through these features. Surface low will develop nwd trough wrn ks attended by a warm front. Dryline will mix ewd through wrn tx...wrn ok and wrn ks before once again retreating overnight. Farther east a weak occluded low and front will persist over the mid atlantic region.

...cntrl and srn plains...

Elevated storms developing in warm advection regime should be in progress from nrn ks into neb. In wake of morning storms...the atmosphere will destabilize south of advancing warm front from cntrl ks...wrn/cntrl ok into n-cntrl and ern portion of wrn tx as richer moisture advects nwd. Diabatic warming of the moistening boundary layer and 7-7.5 c/km mid-level lapse rates will contribute to 2000-2500 j/kg mlcape. Surface low will develop nwd through wrn ks as another in a series of vorticity maxima rotate through ern periphery of upper low. This zone of stronger forcing suggests storms will be more likely to initiate first near triple point over cntrl ks. More isolated activity will be possible farther s as the dryline mixes ewd through wrn ok and nwrn tx. Vertical shear from
35-45 kt will support supercells with large hail likely. Isolated tornadoes will also be possible...initially near triple point/warm front over cntrl ks where backed sely flow will result in larger 0-1 km hodographs. A small window for isolated tornadoes will also exist farther south across ok into tx during the early evening as the llj strengthens and before the boundary layer decouples.

Additional storms...likely more linear in nature...may develop late thursday night from wrn tx into wrn ok as pacific front overtakes the retreating dryline. This activity could pose a threat for isolated hail and strong wind gusts.


Day 2 convective outlook
nws storm prediction center norman ok
1205 am cdt thu may 19 2011

valid 201200z - 211200z

...there is a slgt risk of svr tstms across the central and southern plains...

...plains...

Weak height falls will overspread the plains friday as mid level trough edges out of the inter-mountain west. Both the nam and gfs suggest a closed low will rotate into the nrn rockies/high plains region...mt/wy/sd...while somewhat stronger forcing ejects across the srn rockies into ks/ok/tx early in the period. In fact latest guidance suggest thunderstorms will be ongoing at the beginning of the period...or develop shortly after sunset...across the srn and cntrl plains in response to ewd moving shortwave. Maritime tropical airmass has finally spread into south tx this morning and this moisture will gradually return to much of the outlook area with high pwat values...likely in excess of 1.5 inches...expected to contribute to widespread instability and clouds. For this reason diurnal heating may be somewhat limited and large scale forcing should easily enhance scattered-numerous showers/thunderstorms across much of the warm sector. Convective mode and timing will prove difficult given the very moist airmass and early large scale support for convective development. At this time it appears multiple thunderstorm clusters with embedded supercells could easily evolve within a strongly sheared but likely complicated storm mode environment. If early-mid day activity evolves as models suggest then heating near the dryline may not lead to more than isolated activity in the wake of potentially significant thunderstorms or mcss.