Hoosier Posted April 27, 2014 Share Posted April 27, 2014 Chasers may have a bit of a dilemma for Monday. Greater severe potential should be down south but a 30% area in relatively chaser-friendly Illinois. DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT SUN APR 27 2014 VALID 281200Z - 291200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF MS/AL/TN/LA... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID-SOUTH/MIDWEST TO THE OH RIVER VALLEY/SOUTHERN APPALACHIANS... ...SUMMARY... AN OUTBREAK OF SEVERE STORMS INCLUDING STRONG TORNADOES AND WIDESPREAD DAMAGING WINDS APPEARS LIKELY MONDAY AND MONDAY NIGHT ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY AND TENNESSEE VALLEY. ...SYNOPSIS... AN EXTENSIVE CLOSED LOW/PARENT LONGWAVE TROUGH OVER THE CENTRAL CONUS WILL SHIFT SLOWLY EASTWARD ON MONDAY...WHILE ONE OR MORE DISTURBANCES/HIGHER-LEVEL SPEED MAXIMA EJECT EAST-NORTHEASTWARD THROUGH THE BASE OF THE TROUGH TOWARD THE OZARKS AND LOWER/MIDDLE MS RIVER VALLEY. THE PRIMARY SURFACE CYCLONE WILL MOVE SLOWLY ACROSS THE MIDDLE MO RIVER VALLEY...WITH A WARM FRONT EXTENDING EAST-SOUTHEASTWARD ACROSS THE NEIGHBORING MIDWEST. A COMPOSITE DRYLINE/PACIFIC COLD FRONT WILL SLOWLY SPREAD EAST-SOUTHEASTWARD ACROSS PARTS OF THE LOWER MO VALLEY/OZARKS AND SOUTHEAST TX/TX GULF COAST. ...TN VALLEY/CENTRAL GULF COAST STATES/ARKLAMISS... INITIALLY...IT SEEMS LIKELY THAT CLUSTERS OF TSTMS WILL BE ONGOING ACROSS THE REGION MONDAY MORNING...PARTICULARLY NEAR/EAST OF THE MS RIVER INTO PARTS OF THE OH/TN RIVER VALLEYS. SOME OF THESE STORMS MAY BE SURFACE-BASED OR NEARLY SO AND CAPABLE OF AN EARLY DAY SEVERE THREAT. FROM THE DAY 2 PERSPECTIVE...IT SEEMS VIABLE THAT THIS CONVECTION MAY INFLUENCE /VIA OUTFLOW AND DIFFERENTIAL HEATING/ THE NORTHWARD EXTENT OF THE PEAK SEVERE RISK SUBSEQUENTLY MONDAY AFTERNOON INTO MONDAY NIGHT. MEANWHILE...AN INCREASINGLY BROAD/EAST-NORTHEASTWARD SHIFTING PLUME OF 60S F SURFACE DEWPOINTS WILL RESIDE ACROSS THE MAJORITY OF THE REGION VIA THE DIURNAL MAINTENANCE OF MODERATELY STRONG SOUTHWESTERLY LOW-LEVEL WINDS. AMPLE HEATING IN CONVECTIVE/OUTFLOW-FREE AREAS WILL LIKELY LEAD TO MODERATE BUOYANCY /1500-2500 J PER KG MLCAPE/ WITHIN AN INCREASING INHIBITION-FREE WARM SECTOR BY AFTERNOON/EARLY EVENING. ESPECIALLY GIVEN CURRENT EXPECTATIONS OF EARLY DAY CONVECTION/POTENTIAL OUTFLOW...SUCH DESTABILIZATION APPEARS MOST PROBABLE WITHIN A CORRIDOR FROM THE SABINE RIVER VICINITY OF TX/LA NORTHEASTWARD ACROSS MS INTO NEIGHBORING AL/TN. AS THE AIR MASS DESTABILIZES...STORMS SHOULD DEVELOP/REINVIGORATE PARTICULARLY WITHIN A CORRIDOR OF AMPLE/MOIST LOW-LEVEL CONFLUENCE ACROSS NORTHERN/CENTRAL MS AND LA INTO WESTERN/MIDDLE TN AND WESTERN/NORTHERN AL. THIS COULD BE AS EARLY AS AFTERNOON...BUT ESPECIALLY INTO THE EVENING HOURS AS AN EMBEDDED IMPULSE/SPEED MAX WITHIN THE BASE OF THE LONGWAVE TROUGH BEGINS TO APPROACH/OVERSPREAD THE REGION. HIGHLIGHTED BY A 75-100 KT SOUTHWESTERLY MID-LEVEL SPEED MAX...BOTH DEEP LAYER/LOW-LEVEL SHEAR WILL BE QUITE STRONG ACROSS THE REGION WITH EFFECTIVE BULK SHEAR OF 50+ KT. SCENARIO SHOULD YIELD AN EXPANDING/INTENSIFYING CORRIDOR OF STORMS...AGAIN PARTICULARLY BY MONDAY EVENING...WHICH WOULD LIKELY INCLUDE A MULTI-MODAL SCENARIO OF SEMI-DISCRETE SUPERCELLS AND A NOCTURNAL TREND TOWARD HIGHLY-ORGANIZED QUASI-LINER BANDS WITH BOWS/LEWP STRUCTURES. SEVERE HAIL ASIDE /AFTERNOON THROUGH EARLY EVENING/...TORNADOES...INCLUDING A VIABLE POTENTIAL FOR STRONG TORNADOES...CAN BE EXPECTED ALONG WITH THE POSSIBILITY OF WIDESPREAD DAMAGING WINDS THROUGH THE EVENING/OVERNIGHT HOURS AS STORMS DEVELOP EAST/NORTHEASTWARD ESPECIALLY ACROSS MS/AL/TN. ...MIDWEST... NEAR/SOUTH OF A WARM FRONT ACROSS THE REGION...THE AIR MASS SHOULD STEADILY DESTABILIZE MONDAY AFTERNOON IN THE WAKE OF EARLY DAY ELEVATED CONVECTION/CLOUD COVER. LOWER TOPPED STRONG/SEVERE TSTMS WILL BE POSSIBLE MONDAY AFTERNOON/EARLY EVENING...POTENTIALLY AS FAR WEST-NORTHWEST AS IA IN VICINITY OF THE SURFACE LOW/NARROWING WARM SECTOR. SEVERE HAIL AND SOME TORNADOES WILL BE POSSIBLE ACROSS THE REGION...MAINLY PRIOR TO THE MID-EVENING HOURS. ..GUYER.. 04/27/2014 Link to comment Share on other sites More sharing options...
andyhb Posted April 27, 2014 Author Share Posted April 27, 2014 Not upgrading to a high risk is quite weird there considering all of the parameters coming together in AR. That outlook was weirdly written too... Eastern Western Kansas? How about West Central Kansas? There was more attention paid to the areas that were outside the highest risk locations, to be honest. Link to comment Share on other sites More sharing options...
BuffaloWeather Posted April 27, 2014 Share Posted April 27, 2014 Not upgrading to a high risk is quite weird there considering all of the parameters coming together in AR. That outlook was weirdly written too... Eastern Western Kansas? How about West Central Kansas? Has there ever been 3 straight days of Moderate Risk from the SPC before? Link to comment Share on other sites More sharing options...
andyhb Posted April 27, 2014 Author Share Posted April 27, 2014 Has there ever been 3 straight days of Moderate Risk from the SPC before? The D1, D2 and D3 risks on 4/25/11. Link to comment Share on other sites More sharing options...
Indystorm Posted April 27, 2014 Share Posted April 27, 2014 Since this is the first significant outbreak of this season a reminder is necessary of usual procedures. When things get fast and furious it is helpful to post only confirmed tor warnings, radars, screen captures, significant damage, etc. instead of every svr warning. I personally appreciate radars since I'm pretty much limited to NWS radars myself. I have a strong feeling that we may be overwhelmed starting later today as the line upzips from Omaha to the Arklatex. Link to comment Share on other sites More sharing options...
andyhb Posted April 27, 2014 Author Share Posted April 27, 2014 Wednesday is also looking rather volatile on the EC this run of the Euro, just another thing to look at. Link to comment Share on other sites More sharing options...
hm8 Posted April 27, 2014 Share Posted April 27, 2014 Not a super-strongly worded D3 outlook... Link to comment Share on other sites More sharing options...
JoMo Posted April 27, 2014 Share Posted April 27, 2014 I'm more than a bit confused about what to expect today after reading Springfield, MO's morning AFD. Also looking at various model solutions and reading the latest SPC Mesoscale discussion has left me even more confused about when convection will fire and how many 'rounds' there will be and the impacts expected. Link to comment Share on other sites More sharing options...
jcwxguy Posted April 27, 2014 Share Posted April 27, 2014 First 2 severe thunder storm watches of this outbreak have been posted for parts of Oklahoma and Kansas Sent from my LG-LS980 using Tapatalk Link to comment Share on other sites More sharing options...
jmt Posted April 27, 2014 Share Posted April 27, 2014 I'm more than a bit confused about what to expect today after reading Springfield, MO's morning AFD. Also looking at various model solutions and reading the latest SPC Mesoscale discussion has left me even more confused about when convection will fire and how many 'rounds' there will be and the impacts expected. I agree. I am wondering now if the SPC aligns with their thinking in the 8AM outlook. SGF is certainly downplaying any TOR possibilities. Link to comment Share on other sites More sharing options...
Ozarkwx Posted April 27, 2014 Share Posted April 27, 2014 That spc disco used a lot of words like unclear and not certain. Anyway Tulsa cut the severe warned percentages in W. Ar from the 60-70 range almost in half on the decision support page. It will be interesting to see the next Day 1 Outlook. Sent from my XT1060 using Tapatalk Link to comment Share on other sites More sharing options...
PGM Posted April 27, 2014 Share Posted April 27, 2014 First post.. I really think a high risk area for central and northern Arkansas and southern Missouri was justified. I guess we will see just how things turn out later. We already got some severe cells firing up in Oklahoma and Kansas. Link to comment Share on other sites More sharing options...
JoMo Posted April 27, 2014 Share Posted April 27, 2014 That spc disco used a lot of words like unclear and not certain. Anyway Tulsa cut the severe warned percentages in W. Ar from the 60-70 range almost in half on the decision support page. It will be interesting to see the next Day 1 Outlook. Sent from my XT1060 I see 60's in NW Arkansas and even a 47 up near Miami, OK as of 6:19 AM? That's higher than the last update I saw. Also tornado is "28" where you are at I believe, which is the highest on the page? Link to comment Share on other sites More sharing options...
LocoAko Posted April 27, 2014 Share Posted April 27, 2014 First post.. I really think a high risk area for central and northern Arkansas and southern Missouri was justified. I guess we will see just how things turn out later. We already got some severe cells firing up in Oklahoma and Kansas. Not great timing for the OKC Memorial Marathon this morning. Link to comment Share on other sites More sharing options...
Ozarkwx Posted April 27, 2014 Share Posted April 27, 2014 I see 60's in NW Arkansas and even a 47 up near Miami, OK as of 6:19 AM? That's higher than the last update I saw. Also tornado is "28" where you are at I believe, which is the highest on the page? You are right that is what the page says now. Maybe I should not post any information till I am fully awake, lol. Link to comment Share on other sites More sharing options...
OKpowdah Posted April 27, 2014 Share Posted April 27, 2014 Need to continue to pay close attention to central OK tonight / tomorrow morning. RAP and SPC wrf blow up a nice line ahead of the DL as strong upper level forcing moves in, with still 2000J/kg of CAPE in place, and a heck of a lot of low level shear RAP and SPC WRF nailed this morning. Link to comment Share on other sites More sharing options...
JoMo Posted April 27, 2014 Share Posted April 27, 2014 RAP and SPC WRF nailed this morning. Yeah, I was about to make a comment that the SPC WRF seems to have nailed the situation unfolding now how it expected. Also the Euro wasn't too bad as well. Link to comment Share on other sites More sharing options...
PGM Posted April 27, 2014 Share Posted April 27, 2014 Not great timing for the OKC Memorial Marathon this morning. KFOR is reporting the run has been delayed until 7:15 local. Wouldn't be surprised if it is delayed some more given the severe weather. Link to comment Share on other sites More sharing options...
LocoAko Posted April 27, 2014 Share Posted April 27, 2014 KFOR is reporting the run has been delayed until 7:15 local. Wouldn't be surprised if it is delayed some more given the severe weather. It should be... there are plenty of storms behind that. Not sure why it wasn't delayed more unless it is typical to do this in short increments. Pulsing ZDR arc implying at least weak updraft helicity on the southern storm entering the metro with very brief TVSs reported over the past hour. Fun times this morning. Link to comment Share on other sites More sharing options...
huronicane Posted April 27, 2014 Share Posted April 27, 2014 It should be... there are plenty of storms behind that. Not sure why it wasn't delayed more unless it is typical to do this in short increments. I know that http://perryweather.com/ is providing some support for the marathon, but it seems to me that marathon officials are not getting (good/any) information from him regarding the storms, because if so, they would have delayed the race until at least 8. Link to comment Share on other sites More sharing options...
LocoAko Posted April 27, 2014 Share Posted April 27, 2014 I know that http://perryweather.com/ is providing some support for the marathon, but it seems to me that marathon officials are not getting (good/any) information from him regarding the storms, because if so, they would have delayed the race until at least 8. NWS Norman @NWSNorman 8m 655am-Downtown OKC will be most affected by strong/severe storms 715-745 am with half dollar hail/60 mph gusts possible. The Significant Weather Advisory for OKC is urging those attending the marathon to take shelter for imminent dangerous weather conditions. Hope that is being heeded! Link to comment Share on other sites More sharing options...
LocoAko Posted April 27, 2014 Share Posted April 27, 2014 62MPH gust at both the Yukon, OK ASOS and the Piedmont, OK Mesonet site. KRCE 271155Z AUTO 22008G54KT 030V030 3/4SM +TSRA BKN002 17/16 A2951 RMK AO2 P0060 Link to comment Share on other sites More sharing options...
PGM Posted April 27, 2014 Share Posted April 27, 2014 NWS Norman @NWSNorman[/size] 8m 655am-Downtown OKC will be most affected by strong/severe storms 715-745 am with half dollar hail/60 mph gusts possible. The Significant Weather Advisory for OKC is urging those attending the marathon to take shelter for imminent dangerous weather conditions. Hope that is being heeded! Marathon has now been delayed until 8am local, as it should be! Link to comment Share on other sites More sharing options...
huronicane Posted April 27, 2014 Share Posted April 27, 2014 NWS Norman @NWSNorman 8m 655am-Downtown OKC will be most affected by strong/severe storms 715-745 am with half dollar hail/60 mph gusts possible. The Significant Weather Advisory for OKC is urging those attending the marathon to take shelter for imminent dangerous weather conditions. Hope that is being heeded! It is hard to get thousands of people into sheltered areas around there, but the marathon is now delayed until 8 (https://www.facebook.com/OKCMarathon). I have to wonder what sort of actual support is being provided to the marathon by Perry Weather, and if anything will change in future years. I remember when the partnership was announced a year or two ago, the NWS in Norman was wondering why they'd outsource to some recent college graduate in Northern Texas when they had much better options in the Norman area. Link to comment Share on other sites More sharing options...
OceanStWx Posted April 27, 2014 Share Posted April 27, 2014 Sorry for going slightly off-topic, but why does the SPC's thunderstorm outlook not correspond with NWS forecasts? As an example, the most recent SPC TO has Topeka at a 10% chance to see thunder all day, meanwhile my NWS forecast says 70% chance. Is it because the NWS forecast is for precipitation in general? Thanks in advance, guys. Vastly different things are being forecast here. The NWS WFO is forecasting probability of precipitation (at least 0.01") across either that time period or the areal coverage. The SPC is forecasting a 10% chance of a tornado within 25 miles of any given point. The SPC forecasts are based on the average daily probabilities of a tornado occurring within 25 miles of a point. I don't know the exact numbers for the TOP area off the top of my head, but let's say any given day is a 0.5% chance of a tornado occurring within 25 miles. The 10% forecast today is saying that today the risk is 20 times greater than the average day. 10% is a small number, but in this case is actually a hugely elevated risk. Link to comment Share on other sites More sharing options...
KSWx Posted April 27, 2014 Share Posted April 27, 2014 Vastly different things are being forecast here. The NWS WFO is forecasting probability of precipitation (at least 0.01") across either that time period or the areal coverage. The SPC is forecasting a 10% chance of a tornado within 25 miles of any given point. Is that what you were referring to as well? The SPC forecasts are based on the average daily probabilities of a tornado occurring within 25 miles of a point. I don't know the exact numbers for the TOP area off the top of my head, but let's say any given day is a 0.5% chance of a tornado occurring within 25 miles. The 10% forecast today is saying that today the risk is 20 times greater than the average day. 10% is a small number, but in this case is actually a hugely elevated risk. Thanks for the response. To clarify, I'm talking about the enhanced thunderstorm outlook as opposed to the convective outlook product. Link to comment Share on other sites More sharing options...
brettjrob Posted April 27, 2014 Share Posted April 27, 2014 Crapvection. Crapvection everywhere, and it's only 12z. Not elevated showers that will die out, but intense surface-based storms with 50 kft tops. To anyone who wondered why they didn't go HIGH last night for the initial SWODY1, I think you have your answer. Today will still be dangerous and there will still be tornadoes, probably quite a few, but the highly-organized threat over a wide latitudinal expanse is in trouble IMHO. Just to clarify, the open warm sector threat over AR/LA and perhaps E OK/NE TX is still robust, and that probably had the highest ceiling all along. It's just that the dryline itself convected in earnest far too early to maximize the threat with that mode. Link to comment Share on other sites More sharing options...
OceanStWx Posted April 27, 2014 Share Posted April 27, 2014 Thanks for the response. To clarify, I'm talking about the enhanced thunderstorm outlook as opposed to the convenctive outlook product. I see, the idea works similarly though. The SPC product is saying thunder should happen 1 out of every 10 times they forecast it, whereas the NWS WFO is saying there is a 70% chance of 0.01" rain, not necessarily a 70% chance of thunder. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 27, 2014 Share Posted April 27, 2014 Still plan on playing the broken line of sups that should evolve later along the line as it progresses into west-central/southwest MO. Probably between Joplin and Nevada. Link to comment Share on other sites More sharing options...
janetjanet998 Posted April 27, 2014 Share Posted April 27, 2014 CONCERNING...SEVERE THUNDERSTORM WATCH 92...93... VALID 271255Z - 271430Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 92...93...CONTINUES. SUMMARY...SEVERE WEATHER THREAT WILL CONTINUE ACROSS WW 92 AND 93 WITH AN ADDITIONAL THREAT OF HAIL AND DAMAGING WINDS S OF WW 93 IN N TX. TSTMS WILL BECOME INCREASINGLY SURFACE-BASED WITH EWD PROGRESSION...INCREASING THE THREAT OF BOTH DAMAGING WINDS AND TORNADOES. DISCUSSION...TSTM ACTIVITY WITHIN THE TWO WATCHES APPEARS TO BE PART OF TWO SEPARATE REGIMES. ACTIVITY WITHIN WW 92 IS LIKELY TIED TO INCREASED ASCENT ASSOCIATED WITH A LEAD SHORTWAVE AND ITS ASSOCIATED SPEED MAX. THIS ACTIVITY WAS INITIALLY ELEVATED /CONFIRMED BY 12Z TOP SOUNDING/ AND WILL LIKELY CONTINUE TO BE OVER THE NEXT SEVERAL HOURS AS IT PROGRESSES NEWD. AS A RESULT...THE MAIN THREAT REMAINS SEVERE HAIL. ANY SURFACE-BASED ACTIVITY WILL LIKELY BE DELAYED UNTIL THIS AFTERNOON WHEN THE COLD FRONT MOVES THROUGH. MOST OF THE TSTMS IN WW 93 APPEAR TO BE SURFACE /OR AT LEAST NEAR-SURFACE/ ORIENTATED AS A MORE EWD MOTION HAS BEEN OBSERVED WITH RECENT RADAR IMAGERY. SEVERE GUSTS HAVE ALSO ALREADY BEEN REPORTED. THIS ACTIVITY INITIATED ALONG THE COLD FRONT BUT HAS NOW DECOUPLED FROM IT AND MOVED INTO THE WARM SECTOR. WARM SECTOR ACROSS ERN OK MAY STILL BE A BIT HOSTILE TOWARDS SURFACE-BASED CONVECTION BUT THAT SHOULD CHANGE QUICKLY AS MOISTURE CONTINUES TO ADVECT NWD AND LARGE SCALE LIFT PERSISTS OVER THE AREA. AS A RESULT...THE SVR RISK WILL CONTINUE WITH AN INCREASING THREAT FOR A FEW TORNADOES. FARTHER S...SURFACE-BASED TSTMS HAVE DEVELOPED ALONG THE FRONT ACROSS NW TX WITH ELEVATED TSTMS AHEAD OF THIS ACROSS N TX. SOME ISOLATED HAIL IS POSSIBLE WITH THE ELEVATED CONVECTION WITH HAIL AND DAMAGING WINDS POSSIBLE WITH THE SURFACE-BASED STORMS FARTHER W. Link to comment Share on other sites More sharing options...
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