OceanStWx Posted March 29, 2011 Share Posted March 29, 2011 Its more than region, its time of year, I heard Vortex 2 waited until later because of generally slower storm motions and easier chasing Slower storm motions and less chance for chaser convergence were definitely considered when deciding to include June rather than April in the operational window. And it is true that by early June you don't expect 100 knot jet streaks at 500 mb across the Midwest, like you might in early April. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 29, 2011 Share Posted March 29, 2011 This storm looks sick regarding flood potential over the Northern Plains. This storm is essentially an extension of the East Asian Pacific jet plowing across the Pacific following the breakdown of the high latitude blocks. Last time the East Asian Pacific jet took a meander into the plains? Last one I can think of is Octobomb. Link to comment Share on other sites More sharing options...
Hoosier Posted March 29, 2011 Share Posted March 29, 2011 This storm looks sick regarding flood potential over the Northern Plains. This storm is essentially an extension of the East Asian Pacific jet plowing across the Pacific following the breakdown of the high latitude blocks. Last time the East Asian Pacific jet took a meander into the plains? Last one I can think of is Octobomb. Funny, I was thinking of the Octobomb earlier but wasn't sure how good of a comparison it was. Link to comment Share on other sites More sharing options...
Hoosier Posted March 29, 2011 Share Posted March 29, 2011 Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 29, 2011 Share Posted March 29, 2011 Funny, I was thinking of the Octobomb earlier but wasn't sure how good of a comparison it was. It does bear some resemblance--although Octobomb was the mother of all jet streaks. Winter/flood thread started for those interested. http://www.americanwx.com/bb/index.php/topic/16204-winterflooding-storm-threat-april-3-5/ Link to comment Share on other sites More sharing options...
Hoosier Posted March 29, 2011 Share Posted March 29, 2011 Not trying to make a comparison but it's funny that this potential event is falling on April 3-4. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 29, 2011 Share Posted March 29, 2011 The 0z GFS for this coming saturday went back to showing the moisture/instability it was showing the other day with near mid 60 dews along the dryline and a nice area of >1500 j/kg of CAPE. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 29, 2011 Share Posted March 29, 2011 Not trying to make a comparison but it's funny that this potential event is falling on April 3-4. And hopefully the 2nd Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 29, 2011 Share Posted March 29, 2011 The 0z GFS for this coming saturday went back to showing the moisture/instability it was showing the other day with near mid 60 dews along the dryline and a nice area of >1500 j/kg of CAPE. Another run that says i'm chasing on Sunday. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 29, 2011 Share Posted March 29, 2011 Another run that says i'm chasing on Sunday. Ya a nice run bringing near mid 60 dews up to the MO/IA/IL intersection. Link to comment Share on other sites More sharing options...
Hoosier Posted March 29, 2011 Share Posted March 29, 2011 Ya a nice run bringing near mid 60 dews up to the MO/IA/IL intersection. It's probably not going to handle the surface temps well either if we get a setup like this. If that steep mid level lapse rate environment is in place, then instability could end up being underdone. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 29, 2011 Share Posted March 29, 2011 some serious deep moisture return between 96-120hr on the GFS into OK/KS. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 29, 2011 Share Posted March 29, 2011 some serious deep moisture return between 96-120hr on the GFS into OK/KS. It is all about the wave amplitude and subsequent cross barrier flow. Dry runs have a much lower amplitude initial wave (see Euro 12Z/CMC 12Z). I do see the latest CMC went with a much more amplified wave on the 0Z. GFS suggests a beefy backside jet digging in behind the initial IPV impulse ejecting into the plains--hence the much more impressive moisture return. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 29, 2011 Share Posted March 29, 2011 The new "E-N" rule--Euro-NOGAPS. They both really amplify that PNA ridge and cut off the secondary upper low from the main belt of westerlies. Link to comment Share on other sites More sharing options...
SmokeEater Posted March 29, 2011 Share Posted March 29, 2011 Can you guys add today, and possibly the next 2 days to the thread title? Looks like possibly a halfway decent event today, with Slight Risks the next 2 days. DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1256 AM CDT TUE MAR 29 2011 VALID 291200Z - 301200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY TO SOUTH CENTRAL TX/LOWER RIO GRANDE VALLEY... ...SYNOPSIS... SHORTWAVE TROUGH CURRENTLY APPROACHING CO PER WATER VAPOR IMAGERY IS EXPECTED TO TURN EWD ACROSS THE CENTRAL PLAINS TODAY AND REACH THE MID MS/LOWER OH VALLEYS BY 12Z WEDNESDAY. MEANWHILE...ZONAL FLOW WILL PERSIST FROM THE SRN ROCKIES TO THE MIDDLE AND SRN ATLANTIC COAST. A SHORTWAVE TROUGH...CURRENTLY MOVING ACROSS THE BAJA REGION...IS EXPECTED TO REACH THE LOWER RIO GRANDE VALLEY BY 30/00Z AND THE NWRN GULF COAST REGION BY THE END OF THE FORECAST PERIOD. LOW LEVEL WINDS ACROSS E TX/LOWER MS VALLEY ARE EXPECTED TO BACK TO SLY TODAY IN RESPONSE TO WEAK HEIGHT FALLS AS THE CO TROUGH PROGRESSES EWD. THIS WILL ALLOW A WARM FRONT TO MOVE NWD INTO SRN LA BY AFTERNOON WITH THE WRN EXTENT OF THIS BOUNDARY REACHING A LITTLE FARTHER NWD INTO EAST CENTRAL TX. MEANWHILE...A COLD FRONT WILL SHIFT S/SEWD THROUGH TX...INTERSECTING THE WARM FRONT OVER EAST CENTRAL TX BY LATE AFTERNOON WITH THE TRAILING PORTION OF THIS FRONT EXTENDING SWWD INTO SOUTH CENTRAL TX. THE COLD FRONT WILL PROGRESS E/SEWD OFF THE TX COAST BY 12Z WEDNESDAY...WITH THE NEWD EXTENSION STRETCHING INTO SRN MS AND NRN AL. ...ARKLATEX TO SERN TX AND EWD INTO LOWER MS VALLEY... SLY LOW LEVEL WINDS DEVELOPING ACROSS THIS REGION WILL ALLOW MOISTURE TO RETURN ACROSS THIS REGION WITH SURFACE DEWPOINTS IN THE MID-UPPER 60S EXPECTED WITHIN THE WARM SECTOR. THIS COMBINED WITH SURFACE HEATING BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES /7.5-8 C PER KM/ WILL RESULT IN MODERATE INSTABILITY /MLCAPE 1500-2000 J PER KG/ BY AFTERNOON. ELEVATED TSTMS...SOME POSSIBLY PRODUCING HAIL...MAY BE ONGOING ACROSS OK AT 12Z TODAY. LOW LEVEL WAA AND WEAK HEIGHT FALLS FROM THE ARKLATEX TO SRN AR/WRN MS SHOULD SUPPORT ELEVATED TSTMS DEVELOPING/SPREADING FROM THE SERN PLAINS THIS MORNING. WEAK INSTABILITY WITH NWD EXTENT SHOULD LIMIT THE SEVERE WEATHER THREAT. HOWEVER...STEEP MIDLEVEL LAPSE RATES AND EFFECTIVE BULK SHEAR AROUND 40 KT SUGGEST THE POTENTIAL FOR A FEW ORGANIZED STORMS...WITH HAIL THE PRIMARY THREAT N OF THE RETREATING WARM FRONT. MEANWHILE...SURFACE BASED TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG THE COLD FRONT IN E/SERN TX AND EWD ACROSS THE WARM SECTOR IN LA TO SWRN MS. FORCING ATTENDANT TO LOW LEVEL WAA AND LEAD SRN STREAM IMPULSE REACHING THIS REGION BY LATE AFTERNOON WILL SUPPORT THIS ACTIVITY. MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR 40-50 KT WILL SUPPORT ORGANIZED /SUPERCELLULAR/ STORMS. ALTHOUGH LOW LEVEL WINDS WILL TEND TO BE WEAK...VERTICAL VEERING WINDS SUGGEST A POTENTIAL FOR TORNADOES FROM E TX INTO THE LOWER MS VALLEY. IN ADDITION...STEEP MIDLEVEL LAPSE RATES WILL SUPPORT A THREAT FOR HAIL...SOME POSSIBLY VERY LARGE...BUT OVERALL COVERAGE OF SIGNIFICANT HAIL IS UNCERTAIN AT THIS TIME TO INCLUDE A 10 PERCENT SIGNIFICANT HAIL CONTOUR. STRONGER FORCING FOR ASCENT IS EXPECTED TO REACH THE NWRN GULF COAST THIS EVENING AND SPREAD EWD TO THE CENTRAL GULF COAST BY 12Z WEDNESDAY. THIS WILL INDUCE CYCLOGENESIS OVER SERN TX/SWRN LA WITH THE LOW REACHING SERN LA/SERN MS REGION BY EARLY WEDNESDAY MORNING. STRENGTHENING LLJ E OF THE LOW WILL ENHANCE LOW LEVEL SHEAR AND SUPPORT AN OVERNIGHT TORNADO THREAT ACROSS SRN LA TO SERN MS/SWRN AL. ...PARTS OF SOUTH CENTRAL TX/LOWER RIO GRANDE VALLEY... MODELS SUGGEST ISOLATED TSTMS MAY DEVELOP BY LATE AFTERNOON/EARLY EVENING ACROSS THE SRN EXTENT OF THE COLD FRONT AS IT MOVES INTO SOUTH CENTRAL TX...ENCOUNTERING A MODERATELY UNSTABLE AIR MASS /MLCAPE AROUND 2000 J PER KG/. THIS ACTIVITY WILL BE FURTHER SUPPORTED BY FORCING WITH THE BAJA TROUGH AS IT MOVES ACROSS THIS REGION. STORMS THAT DEVELOP IN THIS REGION WILL BE CAPABLE OF PRODUCING LARGE HAIL...SOME VERY LARGE...GIVEN THE DEGREE OF INSTABILITY...STEEP LAPSE RATES AND EFFECTIVE BULK SHEAR AROUND 50 KT FAVORABLE FOR SUPERCELLS. IN ADDITION...DAMAGING WINDS WILL BE A THREAT. THIS ACTIVITY WILL SPREAD SWD IN THE EVENING AND THE DIMINISH AS THE BOUNDARY LAYER STABILIZES WITH THE ONSET OF DIABATIC COOLING. ..PETERS/COHEN.. 03/29/2011 Link to comment Share on other sites More sharing options...
Ed Lizard Posted March 29, 2011 Share Posted March 29, 2011 BUT OVERALL COVERAGE OFSIGNIFICANT HAIL IS UNCERTAIN AT THIS TIME TO INCLUDE A 10 PERCENT SIGNIFICANT HAIL CONTOUR. Hmmm... but they did include it Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted March 29, 2011 Author Share Posted March 29, 2011 From IWX: SUN-MON...INCREASING CHANCE FOR A STRONG MID LEVEL WAVE AND ASSOCIATED SFC WAVE TO AFFECT THE GREAT LAKES. AS STATED ABOVE...PREFERRED A SLOW BIASED GFS SOLUTION ATTM...PLACING THE BULK OF LARGE SCALE FORCING AND DYNAMICS INTO THE MONDAY PERIOD. HENCE OPTED FOR 40 POP THERE. OTHERWISE...RETAINED SUN NIGHT POPS FOR WARM FRONTAL PROCESSES...WITH 30 POPS MON NIGHT GIVEN SYSTEM TIMING UNCERTAINTY. DID ADD THUNDER GIVEN MID LEVEL LAPSE RATE TRENDS AND THE STRONG NATURE OF THIS SYSTEM...FURTHER EXEMPLIFIED IN H5 ANOMALIES. AGAIN...THIS SYSTEM BEARS WATCHING DUE TO THE POTENTIAL FOR A PROLIFIC SEVERE WEATHER EPISODE IF THINGS LINE UP. TOO MUCH UNCERTAINTY STILL PRESENT IN SYSTEM TRACK/TIMING/AND LL MOISTURE DETAILS TO WARRANT ANYTHING MORE THAN A PASSIVE MENTION FOR NOW. WILL CONTINUE TO MONITOR. OTHERWISE...WARMING TEMPS EXPECTED IN THE PERIOD...GIVEN TRENDS IN ADVECTION FIELDS. Link to comment Share on other sites More sharing options...
hm8 Posted March 29, 2011 Share Posted March 29, 2011 If things pan out, this could be the third year in a row that I'll be on vacation for SEMI's first severe weather of the season Link to comment Share on other sites More sharing options...
kab2791 Posted March 29, 2011 Share Posted March 29, 2011 Meh, highly doubtful especially with a Euro solution. If things pan out, this could be the third year in a row that I'll be on vacation for SEMI's first severe weather of the season Link to comment Share on other sites More sharing options...
Indystorm Posted March 29, 2011 Share Posted March 29, 2011 Not trying to make a comparison but it's funny that this potential event is falling on April 3-4. Don't scare me. The current parameters are frightening enough. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 29, 2011 Share Posted March 29, 2011 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0355 AM CDT TUE MAR 29 2011 VALID 011200Z - 061200Z ...DISCUSSION... MODEL CONSENSUS IS THAT PATTERN WILL REMAIN PROGRESSIVE IN THE 4-8 PERIOD WITH THE NEXT IN A SERIES OF SIGNIFICANT SHORTWAVE TROUGHS LIKELY MOVING INTO THE PLAINS DAY 6-7. IT IS CERTAINLY POSSIBLE THAT A SIGNIFICANT SEVERE EVENT COULD EVOLVE OVER THE PLAINS BY DAY 6-7...SPREADING INTO THE LOWER MS VALLEY AND SERN STATES DAY 7-8 AS MOISTURE RETURNS NWD THROUGH PRE-FRONTAL WARM SECTOR. HOWEVER...CONSIDERABLE RUN TO RUN INCONSISTENCIES EXIST WITH THE DETERMINISTIC MODELS AND ENSEMBLE MEMBERS ARE DISPERSIVE BEYOND DAY 5 REGARDING AMPLITUDE AND TRAJECTORY OF THE SHORTWAVE TROUGH. AT THIS TIME PREDICTABILITY REMAINS LOW...BUT PORTIONS OF THE PLAINS INTO THE SERN STATES WILL PROBABLY NEED TO BE INCLUDED IN A RISK AREA IN LATER OUTLOOKS FOR DAY 6-7. ..DIAL.. 03/29/2011 Link to comment Share on other sites More sharing options...
Indystorm Posted March 29, 2011 Share Posted March 29, 2011 Low goes south and is much weaker on the 12z GFS. Wait for the next model runs. Link to comment Share on other sites More sharing options...
AtticaFanatica Posted March 29, 2011 Share Posted March 29, 2011 Slower storm motions and less chance for chaser convergence were definitely considered when deciding to include June rather than April in the operational window. And it is true that by early June you don't expect 100 knot jet streaks at 500 mb across the Midwest, like you might in early April. Right, and in 2010, the project started in the first week of May because that's the peak in violent tornadoes according to climatology. Link to comment Share on other sites More sharing options...
Jim Martin Posted March 29, 2011 Share Posted March 29, 2011 Plenty of cape available for storms. Plenty of moisture available also. However... The cap could be an issue. A strong cap is shown here. Link to comment Share on other sites More sharing options...
Ed Lizard Posted March 29, 2011 Share Posted March 29, 2011 Right, and in 2010, the project started in the first week of May because that's the peak in violent tornadoes according to climatology. First week in May is different than the whole month, but I had heard April has fewer, but more violent tornadoes than May. Link to comment Share on other sites More sharing options...
AtticaFanatica Posted March 29, 2011 Share Posted March 29, 2011 First week in May is different than the whole month, but I had heard April has fewer, but more violent tornadoes than May. Yeah, the last week of April and first week of May are the peak for violent tornadoes, but also for storm motion, which obviously is bad for chasing and worse for research chasing. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 30, 2011 Share Posted March 30, 2011 If it wasn't for the cap on sunday, the 12z GFS is hinting at an interesting setup with dew points in the upper 60's and more instability than previous runs. Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2011 Share Posted March 30, 2011 Day 4-8 outlook mentions a risk area probably being needed later. Link to comment Share on other sites More sharing options...
brettjrob Posted March 30, 2011 Share Posted March 30, 2011 If it wasn't for the cap on sunday, the 12z GFS is hinting at an interesting setup with dew points in the upper 60's and more instability than previous runs. The change in the evolution of the H5 pattern for this weekend over the past 2-4 runs is astounding, and a testament to how abysmal the models have been so far this year. The trough is now supposed to dig a lot more into the Desert SW, bringing a legitimate SW flow pattern that I could actually see producing significant severe (unlike the NW flow, positive-tilt crap shown on earlier runs). Unfortunately, the timing isn't quite right, as this run also hangs the trough back farther W for Sunday. If we could get the digging but also speed things up by about 12 hours, I imagine the cap wouldn't be such a showstopper. In fact, the 12z Mon H5 prog looks nearly classic to me. Normally, I'd be discouraged about the prospects of a solution speeding up by 12 hours this close to the event. But this year, I don't think a 24-hour timing and/or 500-mile spatial change is at all out of the question for a 108-hour forecast. Link to comment Share on other sites More sharing options...
David Reimer Posted March 30, 2011 Share Posted March 30, 2011 The GFS also looks quite interesting for overnight Sunday into Monday. The 12Z GFS has 2,500 J/Kg of SBCAPE over OK at 6 AM Monday with a weak cap by afternoon/evening. I've already made the arrangements in my work schedule so I can be available to chase that day. Should the cap break on Saturday, then that has the potential to be an interesting caprock day. Link to comment Share on other sites More sharing options...
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