May 5-8 Plains/MW/OV/GL Severe Weather, SPC Risk Level: Day 2 & 3 Slight Risk; Forecasts and OBS Options

[WeatherMonger]

SPC mentioning the next prolonged chance at severe for late weekend/early next week. Hopefully something can finally happen around here Monday/Tuesday

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0358 AM CDT WED MAY 02 2012

VALID 051200Z - 101200Z

...DISCUSSION...
MODELS HAVE CONVERGED ON SOLUTION THAT AN UPPER TROUGH FORECAST TO
AMPLIFY OVER THE WRN STATES WILL MOVE INTO THE NRN PLAINS DAY 4
/FRIDAY/ WITH DOWNSTREAM RIDGING FROM THE UPPER MS VALLEY INTO THE
GREAT LAKES. QUASI-STATIONARY FRONT WILL REMAIN FROM THE OH VALLEY
WWD INTO THE CNTRL PLAINS. SOME THREAT FOR A FEW SEVERE STORMS MAY
PERSIST IN VICINITY OF THIS BOUNDARY GIVEN MODERATE TO STRONG
INSTABILITY EXPECTED IN THE WARM SECTOR...ESPECIALLY FROM THE CNTRL
PLAINS INTO THE MID MS VALLEY REGION. HOWEVER...IT APPEARS THE
STRONGER WINDS ALOFT WILL REMAIN IN COOL SECTOR...AND TOO MUCH
UNCERTAINTY EXISTS REGARDING HOW ONGOING CONVECTION WILL MODULATE
WHERE A HIGHER COVERAGE SEVERE THREAT MAY EVOLVE.

IMPULSE EMBEDDED WITHIN THIS TROUGH IS FORECAST TO EJECT INTO SRN
QUEBEC BY DAY 6 WITH REMAINING PORTIONS OF THE POSITIVELY TILTED
TROUGH GRADUALLY SHIFTING SEWD. THIS WILL FORCE WRN PORTION OF THE
FRONT TO ADVANCE SEWD THROUGH THE PLAINS AND MID MS VALLEY. SEVERE
POTENTIAL WILL LIKELY PERSIST AS THIS BOUNDARY INTERACTS WITH THE
UNSTABLE WARM SECTOR. HOWEVER...IT APPEARS THE STRONGER FORCING FOR
DEEP ASCENT WILL LAG THE SFC FRONT WHICH INCREASES UNCERTAINTY
REGARDING THE EXTENT OF STORM COVERAGE GIVEN LIKELIHOOD OF A CAP.
THE GREATEST SEVERE COVERAGE MAY EVOLVE OVER PORTIONS OF THE MID MS
VALLEY INTO THE OH VALLEY BY DAYS 6-7.

..DIAL.. 05/02/2012

This post has been edited by WeatherMonger: May 5 2012, 07:05 AM

[CentralIllinois]

SPC mentioning the next prolonged chance at severe for late weekend/early next week. Hopefully something can finally happen around here Monday/Tuesday

it would be nice pretty boring spring so far lol

[WeatherMonger]

it would be nice pretty boring spring so far lol

I can attest to that and actually raise you a winter I won't be holding my breath with this one, but it's all that's really out there. Who knows, maybe this one will play out

[ChiWxWatcher]

Forbes on Monday's threat:

MON MAY 7
Numerical models again differ, so details of the severe threat area could change in subsequent forecasts. Scattered severe thunderstorms in IL, IN, south half OH, WV, southwest VA, northwest SC, north, central, and southwest GA, FL panhandle, east AL, east half TN, KY, east-central, southeast, and south-central MO, north and west AR, southeast OK, northeast to southwest TX in a strip from near Paris to San Angelo.

[WeatherMonger]

Day 3

DAY 3 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0244 AM CDT THU MAY 03 2012

VALID 051200Z - 061200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE NRN/CNTRL
PLAINS INTO THE UPPER MS VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE SERN
STATES...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF WRN TX...

CORRECTED FOR OUTLOOK GRAPHIC

...SYNOPSIS...

UPPER TROUGH WILL TRANSITION TO A SLIGHTLY MORE AMPLIFIED REGIME BY
SATURDAY WITH A TROUGH EXTENDING FROM THE NRN ROCKIES INTO THE GREAT
BASIN AREA AND A DOWNSTREAM RIDGE OVER THE GREAT LAKES. A SHORTWAVE
TROUGH EMANATING FROM THE SYNOPTIC SCALE TROUGH IS FORECAST TO EJECT
NEWD THROUGH THE NRN PLAINS. FARTHER SOUTH A SRN STREAM IMPULSE
EMBEDDED WITHIN NWLY FLOW SHOULD MOVE THROUGH A PORTION OF THE SERN
STATES. ANOTHER WEAK IMPULSE MAY MOVE INTO WRN TX. AT THE SURFACE A
COLD FRONT WILL MOVE SEWD THROUGH THE NRN AND CNTRL PLAINS AS SFC
LOW ATTENDING THE EJECTING IMPULSE LIFTS INTO SRN MANITOBA. A
QUASISTATIONARY FRONT WILL EXTEND FROM THE UPPER MS VALLEY INTO THE
OH VALLEY. DRYLINE WILL PERSIST OVER THE CNTRL AND SRN HIGH PLAINS.


...NRN/CNTRL PLAINS THROUGH UPPER MS VALLEY...

A MOIST AND UNSTABLE WARM SECTOR WILL RESIDE SOUTH OF THE NW-SE
ORIENTED WARM FRONT AND EAST OF THE DRYLINE AND COLD FRONT OVER THE
CNTRL PLAINS. A FEW ELEVATED STORMS MAY BE ONGOING WITHIN THE ZONE
OF ISENTROPIC ASCENT NORTH OF THE NW-SE ORIENTED BAROCLINIC ZONE
FROM THE NRN PLAINS INTO THE UPPER MS VALLEY. THIS ACTIVITY MAY POSE
SOME RISK FOR HAIL. ADDITIONAL STORMS WILL LIKELY DEVELOP DURING THE
AFTERNOON FROM NEB INTO SD AS THE COLD FRONT SURGES SE IN RESPONSE
TO EJECTING IMPULSE AND INTERACTS WITH THE VERY UNSTABLE WARM
SECTOR. WHILE THE STRONGER WINDS ALOFT ARE EXPECTED TO REMAIN MOSTLY
NORTH OF THE FRONT...SUFFICIENT FLOW WILL OVERLAP A PORTION OF WARM
SECTOR TO AUGMENT VERTICAL SHEAR AND SUPPORT SUPERCELL STORMS.
ACTIVITY WILL ADVANCE SEWD DURING THE EVENING AND MAY EVENTUALLY
EVOLVE INTO AN MCS. LARGE HAIL AND DAMAGING WIND WILL BE THE MAIN
THREATS...BUT A COUPLE TORNADOES CANNOT BE RULED OUT.

...SERN STATES...

A LOW AMPLITUDE SHORTWAVE TROUGH EMBEDDED WITHIN NWLY FLOW WILL
ADVANCE THROUGH THE SERN STATES. A BELT OF 30-35 KT MID LEVEL FLOW
ACCOMPANYING THIS FEATURE WILL MOVE ABOVE THE DESTABILIZING WARM
SECTOR. BOUNDARY LAYER DESTABILIZATION...RESIDUAL OUTFLOW BOUNDARIES
AND DEEPER FORCING FOR ASCENT ATTENDING THE IMPULSE SHOULD
CONTRIBUTE TO THUNDERSTORM DEVELOPMENT DURING THE AFTERNOON WITH AN
ATTENDANT THREAT OF ISOLATED DAMAGING WIND AND HAIL.

...SWRN THROUGH NCNTRL TX...

A FEW THUNDERSTORMS ARE EXPECTED TO ONCE AGAIN DEVELOP ALONG THE
DRYLINE AS THE BOUNDARY LAYER DESTABILIZES...POSSIBLY AIDED BY
ANOTHER SRN STREAM IMPULSE. MODERATE-STRONG INSTABILITY...STEEP
LAPSE RATES AND AT LEAST MODEST VERTICAL SHEAR WILL CONTRIBUTE TO A
THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL FROM LATE AFTERNOON
INTO EARLY EVENING.

..DIAL.. 05/03/2012

[WeatherMonger]

Day 4 area outlooked

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0353 AM CDT THU MAY 03 2012

VALID 061200Z - 111200Z

...DISCUSSION...
MODELS CONTINUE TO INDICATE THAT UPPER TROUGH CURRENTLY IN PROCESS
OF AMPLIFYING OVER THE WRN STATES WILL MOVE THROUGH THE NRN PLAINS
ON SATURDAY INTO SUNDAY. COLD FRONT ACCOMPANYING THIS FEATURE WILL
CONTINUE SEWD THROUGH THE PLAINS AND MID-UPPER MS VALLEY SUNDAY /DAY
4/. SOME THREAT FOR A FEW SEVERE STORMS WILL UNDOUBTEDLY PERSIST
ALONG THIS BOUNDARY AS IT INTERACTS WITH THE MODERATELY TO STRONGLY
UNSTABLE WARM SECTOR...ESPECIALLY FROM THE CNTRL PLAINS INTO THE MID
MS VALLEY REGION. IT APPEARS THE STRONGER WINDS ALOFT WILL REMAIN IN
COOL SECTOR. DESPITE THE WEAK VERTICAL SHEAR...THE THERMODYNAMIC
ENVIRONMENT WILL BE SUPPORTIVE OF SEVERE MULTICELLS THAT SHOULD
ORGANIZE ALONG THE SEWD ADVANCING FRONT.

SOME SEVERE THREAT WILL PERSIST INTO MONDAY /DAY 5/ FROM THE OH
VALLEY SWWD INTO THE SRN PLAINS AS THE COLD FRONT CONTINUES SEWD.
BEYOND THIS TIME...PREDICTABILITY DECREASES AS DETERMINISTIC MODEL
SOLUTIONS AND ENSEMBLE MEMBERS BECOME INCREASINGLY DISPERSIVE.

..DIAL.. 05/03/2012

[wxman1952]

I wonder if any will make it into my neck of the woods? Flint, MI and areas about 45 miles south of me sure don't need anymore water. Parts around there recieved over 5 1/2" thursday.

[WeatherMonger]

I'll post days 2 and 3 here, the day 4-8 outlook makes it sound like they're separate from earlier severe weather. If it is same system as other thread feel free to move and delete this thread

Day 2

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT SAT MAY 05 2012

VALID 061200Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS IL/INDIANA TO ERN
OK...

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NRN FL TO SERN TN...

...SYNOPSIS...
SYNOPTIC PATTERN ALOFT WILL BE CHARACTERIZED BY DEAMPLIFYING MS
VALLEY RIDGING AND RELATED NET HEIGHT FALLS ACROSS MUCH OF ERN
CONUS. PRIMARY SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL
IMAGERY OVER INTERIOR PAC NW -- IS FCST TO MOVE EWD ACROSS NRN
ROCKIES DAY-1...CONTRACTING INTO CLOSED 500-MB CYCLONE OVER MT/SK
BORDER REGION BY START OF PERIOD. LOW SHOULD MOVE EWD ALONG
CANADIAN BORDER TO NERN ND OR NWRN MN BY 7/12Z...WITH POSITIVELY
TILTED TROUGH SWWD ACROSS WRN SD AND WY. MEANWHILE...WEAKER
SHORTWAVE TROUGH WILL MOVE SLOWLY SEWD OVER COASTAL CA AND MAY
DEVELOP SMALL/CLOSED 500-MB CYCLONE BY END OF PERIOD OVER OR NEAR
SRN PORTIONS CA/NV. PROGS REMAIN QUITE DIFFERENT BY END OF PERIOD
REGARDING AMPLITUDE/POSITION OF THIS FEATURE. WEAK/SRN-STREAM
PERTURBATION...NOW EVIDENT IN VWP/PROFILER DATA AND SATELLITE
IMAGERY OVER WRN AR -- IS FCST TO DRIFT SEWD OVER PORTIONS AL/GA BY
7/12Z...BECOMING PART OF BROAD/WEAK AREA OF CYCLONIC FLOW OVER NERN
GULF AND FL.

AT SFC...LEE-SIDE LOW NOW OVER CENTRAL HIGH PLAINS IS FCST TO
MIGRATE TO SERN SD/NWRN IA AREA BY 6/12Z...COLD FRONT EXTENDING SWWD
INTO SECONDARY/FRONTAL-WAVE LOW OVER SRN KS OR NWRN OK. WAVY
FRONTAL ZONE -- NOW ANALYZED FROM DELMARVA REGION TO INDIANA AND NEB
-- IS EXPECTED TO MOVE SWD AS COLD FRONT ACROSS CAROLINAS TO NRN GA
BY START OF PERIOD. BOUNDARY SHOULD BECOME QUASISTATIONARY NWWD
OVER TN VALLEY THEN WARM FRONT ACROSS SRN/WRN IL AND IA. FRONTAL
POSITION MAY BE MODULATED SOMEWHAT THROUGHOUT PERIOD BY OUTFLOW FROM
CONVECTIVE COMPLEXES. BY 7/00Z...WARM FRONT SHOULD LIFT NEWD ACROSS
IL AND PORTIONS LOWER OH VALLEY...WHILE COLD FRONT REACHES PORTIONS
SERN KS...OK AND NW TX. EVEN BY MIDDLE OF PERIOD...MESOSCALE
DISCREPANCIES ARE APPARENT IN PROGGED FRONTAL POSITIONS THAT WILL BE
CRUCIAL TO GREATEST SVR PROBABILITIES.

...IL/INDIANA TO ERN OK...
SCATTERED TO LOCALLY NUMEROUS TSTMS SHOULD DEVELOP INVOF SFC COLD
FRONT DURING AFTERNOON...WHILE CONDITIONAL POTENTIAL FOR SVR
CONVECTION EXISTS OVER WARM FRONT. DAMAGING HAIL/GUSTS ARE MAIN SVR
THREATS.

LACK OF DEEP-LAYER SHEAR OVER MOST OF THIS CORRIDOR SUGGESTS
PREDOMINANTLY MULTICELLULAR MODE...ALTHOUGH BRIEF SUPERCELL
STRUCTURES ARE POSSIBLE. WARM SECTOR WILL BE CHARACTERIZED COMMONLY
BY MID-UPPER 60S SFC DEW POINTS...WITH POCKETS OF 70S F...BENEATH
STEEP MIDLEVEL LAPSE RATES. STG SFC DIABATIC HEATING IS EXPECTED
WITH MID-LATE AFTERNOON MLCAPE 3500-5000 J/KG IN MUCH OF OUTLOOK
AREA. MOST PROBABLE CORRIDOR FOR SUSTAINED/NOCTURNAL CONVECTION
APPEARS TO BE NEAR WARM FRONT OVER PORTIONS INDIANA/OH...SVR
POTENTIAL DIMINISHING WITH TIME AND EWD EXTENT.

GIVEN UNCERTAINTIES IN FRONTAL POSITION/TIMING AND DIFFERENCES IN
AREAS OF STRONGEST LOW-LEVEL LIFT...SVR OUTLOOK IS KEPT RATHER
BROAD-BRUSHED ATTM. HOWEVER...GIVEN LIKELIHOOD OF STG-EXTREME
INSTABILITY ACROSS MUCH OF PREFRONTAL CORRIDOR...30% SVR
CONCENTRATION EASILY MAY BECOME APPARENT WITHIN THIS AREA IN
SUCCEEDING OUTLOOKS. AS IT STANDS...THREAT EXISTS FOR ISOLATED VERY
LARGE/DAMAGING HAIL IN EARLY STAGES OF CONVECTIVE REGIME...ALONG
WITH SVR HAIL AND GUSTS AS COVERAGE INCREASES ALONG/AHEAD OF FRONT
AND COLD POOLS ACCUMULATE.

...SERN CONUS...
RELATIVE CONCENTRATION OF MULTICELLULAR TSTMS...AND OF RELATED SVR
POTENTIAL...IS FCST INVOF FRONT DURING AFTERNOON INTO EARLY EVENING
FROM NRN FL TO SERN TN. DAMAGING GUSTS AND AT LEAST ISOLATED LARGE
HAIL ARE POSSIBLE. LAPSE RATES ALOFT WILL BE RELATIVELY STEEP FOR
THIS REGION...WITH STG SFC HEATING AND DEW POINTS UPPER 60S TO LOW
70S CONTRIBUTING TO 2500-3500 J/KG MLCAPE. ALTHOUGH
DEEP-TROPOSPHERIC FLOW AND BULK SHEAR ARE EXPECTED TO BE VERY
WEAK...POTENTIAL EXISTS FOR TSTMS TO BUILD INTO FORWARD-PROPAGATING
COMPLEX WITH ACCORDINGLY ENHANCED WIND THREAT MOVING SWD ACROSS THIS
CORRIDOR.

...N-CENTRAL TX TO MID/LOWER RIO GRANDE VALLEY...
BY MID-AFTERNOON...DRYLINE SHOULD INTERSECT COLD FRONT OVER CENTRAL
OR SRN OK AND EXTEND SSWWD ACROSS CENTRAL TX TO N-CENTRAL/NERN
COAHUILA. IN GENERAL...TSTM COVERAGE MAY BE LIMITED BY WEAKER
LOW-LEVEL CONVERGENCE AND SOMEWHAT STRONGER EML-RELATED CINH THAN
ALONG COLD FRONT. STILL...AT LEAST ISOLATED TSTMS MAY DEVELOP INVOF
DRYLINE DURING LATE AFTERNOON...MOVING SLOWLY SEWD. ANY SUSTAINED
TSTM MAY PRODUCE SVR HAIL/GUSTS GIVEN LIKELIHOOD OF 4000-5000 J/KG
MLCAPE AVAILABILITY. HOWEVER...POTENTIAL APPEARS TOO
ISOLATED/CONDITIONAL FOR CATEGORICAL OUTLOOK OVER ENTIRE DRYLINE
CORRIDOR ATTM.

..EDWARDS.. 05/05/2012

[WeatherMonger]

Day 3

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0226 AM CDT SAT MAY 05 2012

VALID 071200Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OH VALLEY REGION TO
MID-SOUTH...

...SYNOPSIS...
PROGRESSIVE MID-UPPER LEVEL PATTERN IS EXPECTED DAY-3...FEATURING
SHORTWAVE TROUGH NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER
INTERIOR PAC NW. BY START OF PERIOD...ASSOCIATED 500-MB LOW SHOULD
BE MOVING EWD ALONG CANADIAN BORDER INVOF NERN ND/NWRN MN...WITH
TROUGH SWWD ACROSS WY. THIS LOW SHOULD MOVE EWD ACROSS LS OR
ADJOINING PARTS OF NWRN ONT THROUGH PERIOD. RELATED SFC
FRONTAL-WAVE CYCLONE SHOULD CURVE EWD TO NEWD FROM IL OR INDIANA
ACROSS UPPER OH VALLEY/LOWER GREAT LAKES REGION. TRAILING COLD
FRONT SHOULD MOVE SEWD ACROSS LOWER OH VALLEY AND ARKLATEX REGION
DURING FIRST HALF OF PERIOD..THEN REACHING UPPER OH VALLEY...CENTRAL
APPALACHIANS...MID-SOUTH AND CENTRAL/SRN TX BY 8/12Z. TX PORTION OF
FRONT MAY STALL BY THEN. AS WITH DAY-2...THERE IS CONSIDERABLE
UNCERTAINTY REGARDING TIMING/POSITION OF COLD FRONT DURING
AFTERNOON...CORRESPONDING TO PERIOD OF MOST PROBABLE CONVECTIVE
INITIATION IN BOTH NEAR-FRONTAL REGIMES DISCUSSED BELOW.

MEANWHILE...PROGS ARE IN GEN AGREEMENT REGARDING PRESENCE OF CLOSED
AND ESSENTIALLY CUT-OFF MID-UPPER LEVEL LOW OVER SWRN CONUS BY
LATTER HALF OF PERIOD. HOWEVER...CONSIDERABLE DIFFERENCES EXIST
REGARDING TIMING AND SUBSYNOPTIC-SCALE SIZE/PLACEMENT OF RELATED
CYCLONE ALOFT.

...OH VALLEY REGION TO MID-SOUTH...
SCATTERED TSTMS IN LINES OR CLUSTERS AGAIN SHOULD DEVELOP INVOF SFC
COLD FRONTAL ZONE DAY-3...OFFERING DAMAGING WIND AND OCNL LARGE
HAIL. LACK OF MORE ROBUST DEEP-LAYER WIND PROFILES INDICATES
PREDOMINANTLY MULTICELLULAR CHARACTER. LAPSE RATES ARE FCST TO
INCREASE FROM NE-SW...WITH FAVORABLE LOW-LEVEL MOISTURE THROUGHOUT
PREFRONTAL WARM SECTOR. BUOYANCY ACCORDINGLY WILL INCREASE FROM
NE-SW...BUT WITH INCREASE IN CINH AND DECREASE IN FRONTAL
CONVERGENCE. GREATEST PARAMETRIC OVERLAPS SHOULD BE FROM LOWER MS
VALLEY AND TN VALLEY REGIONS NEWD TO PORTIONS OH/INDIANA.
RELATIVELY DENSE CONCENTRATIONS OF CONVECTIVE/SVR POTENTIAL ARE
POSSIBLE WITHIN THIS AREA...WHICH IS NECESSARILY BROAD-BRUSHED ATTM
DUE TO PROGNOSTIC UNCERTAINTY...AND SUBJECT TO FUTURE LATERAL
SHIFTING.

...SW TX...LOWER PECOS VALLEY REGION...
STG DIURNAL HEATING...ALONG WITH MOISTURE TRANSPORT...STEEP MIDLEVEL
LAPSE RATES AND FRONTAL ASCENT...MAY BE SUFFICIENT TO SUPPORT TSTMS
OVER PARTS OF THIS REGION. LARGE HAIL AND DAMAGING GUSTS WOULD BE
POSSIBLE. LOW-LEVEL WAA AND MOIST ADVECTION SHOULD SPREAD NWWD OVER
MORE OF SW TX AND SERN NM AFTER 8/00Z...POTENTIALLY SUPPORTING
ADDITIONAL DEVELOPMENT OVER THOSE AREAS. MOST FCST SCENARIOS OF
SERN CONUS LOW POSITION ALSO WOULD SUPPORT STRONG UPPER-LEVEL
DIFLUENCE OVER THIS CORRIDOR...WITH SWATH OF LARGE-SCALE LIFT
BENEATH LEFT-EXIT REGION OF GENTLY CYCLONICALLY CURVED SUBTROPICAL
JET BRANCH. ADDITIONAL TSTMS SHOULD DEVELOP DIURNALLY INTO EARLY
EVENING OVER NEARBY MOUNTAINS OF NRN MEX...HOWEVER WIND PROFILES IN
MOST FCST SOUNDINGS SUGGEST ANY SUCH CONVECTION WILL MOVE SLOWLY
SEWD AND REMAIN OVER MEX.

...SERN CONUS...
AL/GA FRONTAL ZONE DISCUSSED IN DAY-2 OUTLOOK SHOULD BECOME
QUASISTATIONARY THIS PERIOD...BENEATH RESIDUAL MID-UPPER
TROUGHING...PROVIDING SUPPORT FOR CONVECTIVE POTENTIAL IN THAT
REGION. SEA BREEZE AND OUTFLOW BOUNDARIES WILL MORE PRECISELY FOCUS
CONVECTION ON MESOSCALE. WEAK DEEP-LAYER WINDS AND SHEAR SHOULD
KEEP TSTMS MULTICELLULAR IN NATURE...BUT BUOYANCY SHOULD BE
FAVORABLE FOR AT LEAST ISOLATED DAMAGING GUSTS AND LARGE HAIL. MORE
DENSE LOCAL CONCENTRATIONS ALSO ARE POSSIBLE...BUT THAT MESOSCALE
DEPENDENCY PRECLUDES SPECIFIC CATEGORICAL AREA ATTM.

..EDWARDS.. 05/05/2012

[WeatherMonger]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0354 AM CDT SAT MAY 05 2012

VALID 081200Z - 131200Z

...DISCUSSION...
MID-UPPER CYCLONE NEAR CANADIAN BORDER...DESCRIBED IN DAY-2/DAY-3
OUTLOOKS...SHOULD MOVE EWD ACROSS PORTIONS ONT TOWARD SWRN QUE
DAY-4/8TH-9TH. DISCREPANCIES AMONG GUIDANCE GET FAIRLY LARGE BY
THIS TIME REGARDING TIMING/AMPLITUDE OF THIS SYSTEM AND RELATED
TROUGHING SWD ACROSS ERN CONUS. WHILE SOME SVR IS EXPECTED
ALONG/AHEAD OF RELATED SFC COLD FRONT...MOST PROBABLY OVER CENTRAL
APPALACHIANS TO TN VALLEY/MID-SOUTH REGION DAY-4...TOO MUCH
UNCERTAINTY EXISTS REGARDING CONCENTRATION OF ACTIVITY AND FRONTAL
CHARACTERISTICS TO WARRANT AOA 30% UNCONDITIONAL SVR AREA ATTM.

MEANWHILE...AT LEAST ISOLATED SVR MAY OCCUR FROM RIO GRANDE AREA OF
SW TX TO PECOS VALLEY OR ERN NM DAYS 4-6/8TH-11TH...AS PREVIOUSLY
CUT-OFF LOW BECOMES PROGRESSIVE AGAIN. NRN-STREAM PERTURBATION
SHOULD CROSS PAC NW AND NRN ROCKIES DAYS 4-6...POTENTIALLY YIELDING
SOME SVR THREAT OVER NRN PLAINS DAY-6/10TH-11TH. WHILE DEEP-LAYER
SHEAR WILL BE FAVORABLE AHEAD OF THAT TROUGH...LOW-LEVEL MOISTURE
RETURN MAY BE WEAK BASED ON MREF/ECMWF GUIDANCE.

..EDWARDS.. 05/05/2012

[WeatherMonger]

Tomorrows shifted NW and dropped the hatching. Might shift the Day 3 as well, ILX has been mentioning severe chances Sunday and Monday afternoons but SPC only Sunday.

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SAT MAY 05 2012

VALID 061200Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER
MIDWEST...OZARKS...MID MS VALLEY...SRN PLAINS...CNTRL PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE ERN GULF
COAST STATES...

...MID TO UPPER MS VALLEY...
AN UPPER-LEVEL RIDGE WILL BE IN PLACE SUNDAY FROM THE MID-MS VALLEY
NWD INTO THE GREAT LAKES REGION. AT THE SFC...A COLD FRONT WILL MOVE
SEWD ACROSS THE UPPER MIDWEST WITH A BROAD WARM SECTOR IN PLACE
AHEAD OF THE FRONT FROM THE UPPER MS VALLEY EXTENDING SWWD ACROSS
THE OZARKS. AN MCS MAY BE ONGOING NEAR THE FRONT ACROSS PARTS OF THE
REGION SUNDAY MORNING AND OUTFLOW BOUNDARIES ASSOCIATED WITH THE MCS
SHOULD FAVOR CERTAIN AREAS FOR CONVECTIVE INITIATION. AS SFC TEMPS
WARM...NEW CONVECTION SHOULD INITIATE NEAR THOSE BOUNDARIES WHERE
THE AIRMASS HAS BEEN UNDISTURBED. AS STORMS INCREASE IN
COVERAGE...MCS DEVELOPMENT WILL BE POSSIBLE ACROSS THE REGION LATE
SUNDAY AFTERNOON WITH STORMS MOVING SEWD ACROSS THE SLIGHT RISK
AREA.

FORECAST SOUNDINGS ACROSS THE WARM SECTOR IN CNTRL IA...NRN IL AND
NRN MO BY EARLY AFTERNOON HAVE MODERATE INSTABILITY...MLCAPE IN THE
2500 TO 3500 J/KG RANGE WITH 0-6 KM SHEAR OF 30 TO 40 KT. THIS
ENVIRONMENT SHOULD SUPPORT SUPERCELLS AND A THREAT FOR LARGE HAIL
SHOULD EXIST WHERE SUPERCELLS HAVE ACCESS TO STRONG INSTABILITY.
SUPERCELLS SHOULD ALSO HAVE AN ISOLATED TORNADO THREAT.
HOWEVER...FORECAST WIND PROFILES SUGGEST THE DOMINANT STORM MODE IS
QUESTIONABLE. AS WINDS VEER AT LOW-LEVELS AHEAD OF THE APPROACHING
FRONT...LINEAR MULTICELLS MAY DEVELOP WITH A WIND DAMAGE POTENTIAL.
DURING THE LATE AFTERNOON AND EARLY EVENING...A NARROW CORRIDOR WITH
AN ENHANCED SEVERE THREAT COULD EXIST FROM SRN WI SWWD ACROSS NW IL
INTO ERN IA...NRN MO AND FAR ERN KS WHERE THE COMBINATION OF
INSTABILITY/DEEP LAYER SHEAR SHOULD BE MAXIMIZED AND CO-LOCATED WITH
STEEP LAPSE RATES.

...CNTRL AND SRN PLAINS...
AN AXIS OF STRONG INSTABILITY IS FORECAST ACROSS THE SRN PLAINS
SUNDAY AFTERNOON WITH THE MODELS DEVELOPING ISOLATED TO SCATTERED
THUNDERSTORMS AHEAD OF A SEWD MOVING COLD FRONT. THE THERMODYNAMIC
ENVIRONMENT WILL BE FAVORABLE FOR SEVERE STORMS. FORECAST SOUNDINGS
FROM SE KS SWWD ACROSS CNTRL OK SHOW MLCAPE VALUES OF 4000 TO 5000
J/KG WITH LAPSE RATES AROUND 8.0 C/KM. ALTHOUGH DEEP LAYER SHEAR IS
ONLY FORECAST TO BE AROUND 20 KT...THE STRONG INSTABILITY SHOULD
COMPENSATE...MAKING SUPERCELL DEVELOPMENT POSSIBLE ACROSS THE
REGION. LARGE HAIL MAY BE THE GREATEST THREAT ALTHOUGH ANY SUPERCELL
THAT DEVELOPS SHOULD ALSO HAVE A WIND DAMAGE POTENTIAL. AN ISOLATED
TORNADO OR TWO CAN NOT BE RULED OUT. THE SEVERE THREAT SHOULD BE
MORE ISOLATED WITH SSWWD EXTENT IN THE SRN PLAINS DUE TO THE WEAKER
INSTABILITY FORECAST ALONG THE DRYLINE WCNTRL TX.

...ERN GULF COAST STATES...
A BROAD WARM SECTOR IS FORECAST ACROSS THE GULF COAST STATES SUNDAY
WHERE THE MODELS DEVELOP SCATTERED THUNDERSTORMS BY EARLY AFTERNOON.
FORECAST SOUNDINGS SHOW THE STRONGEST INSTABILITY FROM ERN AL SEWD
ACROSS SRN GA WITH MLCAPE IN THE 3000 TO 4000 J/KG RANGE. THIS
COMBINED WITH STEEP LOW-LEVEL LAPSE RATES MAY BE FAVORABLE FOR
ISOLATED DAMAGING WIND GUSTS WITH THE MORE INTENSE PULSE STORMS
SUNDAY AFTERNOON.

..BROYLES.. 05/05/2012

[CIWeather]

Tomorrows shifted NW and dropped the hatching. Might shift the Day 3 as well, ILX has been mentioning severe chances Sunday and Monday afternoons but SPC only Sunday.

What are the chances we miss out on this one too?

[WeatherMonger]

What are the chances we miss out on this one too?

Oh let me count the ways

Im guessing it's going to be just as hard to forecast as the past several days. It's going to depend on where the convective remnants from tonight go. They were counting on the IA cluster last night diving SE and it never happened. I see it as we're in a 15% risk so we're also in an 85% chance of no risk. Although we have to be approaching one of the 15 in 100 times it happens. Thinking I can recall about 80 times it hasn't. 3rd times a charm, right?

[CIWeather]

Oh let me count the ways

Im guessing it's going to be just as hard to forecast as the past several days. It's going to depend on where the convective remnants from tonight go. They were counting on the IA cluster last night diving SE and it never happened. I see it as we're in a 15% risk so we're also in an 85% chance of no risk. Although we have to be approaching one of the 15 in 100 times it happens. Thinking I can recall about 80 times it hasn't. 3rd times a charm, right?

You would think so

[The Snowman]

2:10 Update re-includes hatching.

EDIT: 2:10 Update appears just to be for hatching.



This post has been edited by The Snowman: May 5 2012, 02:37 PM

[The Snowman]

Forbes

SUN MAY 6
Severe thunderstorms in central and east IA, southeast MN, southwest WI, north and west-central IL, north, central, and southwest MO, east KS, northeast OK. Isolated severe thunderstorms in central OK, north-central TX, southwest TN, northeast and east-central MS, northwest, central, and southeast AL, soth GA, FL panhandle and northeast FL. TORCON - 4 southeast IA, west-central IL. A lower chance of an isolated severe thunderstorm in south-central TX.

[WeatherMonger]

I think this is the beginning of this thread, confusing as all get out

MESOSCALE DISCUSSION 0717
NWS STORM PREDICTION CENTER NORMAN OK
0444 PM CDT SAT MAY 05 2012

AREAS AFFECTED...CNTRL TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 052144Z - 052245Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...ISOLATED DRYLINE THUNDERSTORMS MAY BEGIN TO DEVELOP OVER
THE NEXT HOUR OR TWO OVER CNTRL TX...PROGRESSING EWD WITH TIME. A WW
MAY NEED TO BE ISSUED. LARGE HAIL AND DMGG WINDS WILL BE THE PRIMARY
THREATS.

DISCUSSION...2130Z VISIBLE IMAGERY REFLECTS AN INCREASING CU FIELD
ALONG THE DRYLINE...PARTICULARLY EAST OF SJT WHERE RADAR
REFLECTIVITY IS BEGINNING TO INCREASE IN CONCHO COUNTY. HOWEVER...NO
NOTABLE UPPER FEATURE IS EVIDENT THAT WOULD PROVIDE FORCING FOR
ASCENT...WITH WV IMAGERY AND PROFILER DATA GENERALLY IMPLYING
ANTICYCLONIC FLOW ALOFT...POSSIBLY SUPPRESSING MORE WIDESPREAD
POTENTIAL FOR THUNDERSTORM DEVELOPMENT. REGARDLESS...SFCOA INDICATES
NO CONVECTIVE INHIBITION REMAINING. CONVERGENCE ALONG THE DRYLINE
AND EXTREME INSTABILITY MAY BE SUFFICIENT TO OVERCOME SOMEWHAT
HOSTILE CONDITIONS ALOFT. VIGOROUS UPDRAFTS CAN BE EXPECTED IN
STORMS THAT CAN BECOME SUSTAINED...WITH LARGE HAIL AND DMGG WINDS
LIKELY. BRIEF SUPERCELLULAR STRUCTURES MAY BE POSSIBLE GIVEN VERY
SUBTLE LOW-MID LEVEL VEERING...THOUGH GENERALLY WEAK FLOW ALOFT
SHOULD LIMIT GREATER ORGANIZATION.

..HURLBUT.. 05/05/2012


ATTN...WFO...FWD...EWX...SJT...

LAT...LON 30460022 32309949 33039906 33309834 33059771 32249742
30899791 30199866 30039967 30460022

[jdrenken]

I'm heading to the Kirksville-Ottumwa zone tomorrow. Hoping to catch them before they go linear.

[Gilbertfly]

I'm heading to the Kirksville-Ottumwa zone tomorrow. Hoping to catch them before they go linear.

good luck....safe travels brother

[WeatherMonger]

With how poorly the models and forecasting has been the past however long, take it for what it's worth. 5% tornado and 30% wind fields added

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT SUN MAY 06 2012

VALID 061300Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MS VLY SSW INTO
PARTS OF THE SRN PLNS...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SERN
STATES...

...SYNOPSIS...
SRN SK UPR LOW EXPECTED TO TRACK SLOWLY E INTO SRN MB THIS PERIOD AS
TRAILING...POSITIVE TILT TROUGH EDGES MORE SLOWLY E ACROSS THE GRT
BASIN. THE EWD ADVANCE OF THE LOW/TROUGH...AND THAT OF WEAKER
DISTURBANCES TO THEIR E...WILL SERVE TO DEPRESS HEIGHTS FROM THE N
CNTRL STATES INTO THE UPR GRT LKS. LESSER HEIGHT FALLS WILL PREVAIL
OVER THE SRN PLNS AND OVER THE TN VLY/GULF CST STATES IN CONJUNCTION
WITH RESPECTIVE SRN BRANCH DISTURBANCES MOVING NEWD FROM NM AND SEWD
INTO MS/AL.

AT LWR LVLS...SSW-NNE COLD FRONT ASSOCIATED WITH MB/GRT BASIN SYSTEM
WILL ADVANCE E/SE FROM THE LWR MO VLY/CNTRL PLNS THIS MORNING INTO
THE MID MS VLY/SRN PLNS BY EVE. THE SRN PART OF THE FRONT WILL
OVERTAKE THE DRYLINE IN WRN OK...WITH THE DRYLINE CONTINUING S/SW
FROM THERE ACROSS WRN PARTS OF THE TX HILL COUNTRY TO THE TX BIG
BEND. FARTHER NE...FRONT ATTM EXTENDING FROM CNTRL IA TO SRN IND
EXPECTED TO ADVANCE SLOWLY NEWD TODAY...WITH MOVEMENT IN IA LIKELY
OFFSET BY OUTFLOW FROM ONGOING TSTMS.

WHILE LARGE SCALE FORCING FOR ASCENT WILL REMAIN WEAK...SFC HEATING
OF SEASONABLY MOIST/BUOYANT AIR ALONG AND AHEAD OF COLD
FRONT/DRYLINE...AND ALONG WARM FRONT...WILL YIELD A FAIRLY LARGE
AREA SUBJECT TO A CONDITIONAL THREAT FOR SVR TSTMS.

...MID MS VLY SSW INTO PARTS OF THE SRN PLNS TODAY/TNGT...
CNTRL/SW IA SQLN EXPECTED TO CONTINUE SLOWLY E/SE THROUGH THIS
MORNING. WHILE STRONGER STORMS WITHIN THIS BAND REMAINED ISOLD
THROUGH THE OVERNIGHT...UPDRAFTS MAY INTENSIFY/BECOME SUSTAINED
LATER THIS MORNING AS SFC HEATING DESTABILIZES INFLOW. ALTHOUGH
FCST WIND PROFILES AND THE ORIENTATION OF THE CONVECTIVE SYSTEM
RELATIVE TO MEAN SW TO WSWLY MID LVL FLOW DO NOT APPEAR OPTIMAL FOR
INTENSE DEVELOPMENT...SUFFICIENT SHEAR AND INSTABILITY LIKELY WILL
EXIST FOR EMBEDDED STORMS WITH SVR WIND/HAIL. A FEW STORMS MAY FORM
AHEAD OF THE MCS INVOF DIFFUSE WARM/STNRY FRONT IN IL. THESE MAY
YIELD SVR HAIL AND...POSSIBLY...A WEAK TORNADO OR TWO GIVEN
MOIST/BACKED LOW LVL FLOW.

ADDITIONAL TSTMS/STORM CLUSTERS SHOULD FORM THIS AFTN ALONG COLD
FRONT AND RESIDUAL OUTFLOW BOUNDARIES FROM NW MO/NE KS SSW INTO OK.
A BIT LATER IN THE DAY...STORMS ALSO MAY FORM ALONG THE DRYLINE IN
TX. STRONG WARM SECTOR INSTABILITY /SBCAPE TO 4000 J PER KG/
SUGGESTS THE POSSIBILITY FOR SVR HAIL AND WIND. HOWEVER...MODEST
/20-30 KT/ DEEP SWLY SHEAR SHOULD LIMIT UPDRAFT SUSTENANCE/
ORGANIZATION...WITH COMPLEX STORM MODES/SLOWLY-MOVING MULTICELL
CLUSTERS...AND MARGINAL/TRANSIENT SUPERCELLS EXPECTED.
CORRIDORS OF GREATEST SVR RISK WILL BE DETERMINED BY STORM-SCALE
INTERACTIONS GIVEN ABSENCE OF STRONG SHEAR.

LOOSELY-ORGANIZED BANDS/CLUSTERS OF STORMS MAY PERSIST INTO TNGT
E/SE INTO PARTS OF IL...IND...MO...AND AR...BUT WITH A GRADUALLY
DIMINISHING/MORE EPISODIC SVR THREAT.

...SERN STATES TODAY...
SMALL...LOOSELY-ORGANIZED MCS NOW IN NRN AL HAS EVOLVED FROM SIMILAR
OVERNIGHT ACTIVITY THAT EXTENDING UPSTREAM INTO WRN TN. STORMS
SHOULD INCREASE IN COVERAGE AND POSSIBLY STRENGTH TODAY IN RESPONSE
TO STRONG SFC HEATING AND WEAK ASCENT ASSOCIATED WITH AFOREMENTIONED
UPR IMPULSE. WIND FIELD WILL REMAIN WEAK. BUT MODEST MEAN NNWLY
FLOW PARALLEL TO SYSTEM OUTFLOW BOUNDARY...PRESENCE OF EML...AND
HIGH PWS SUGGEST THE POSSIBILITY FOR STORMS TO ORGANIZE INTO
FORWARD-PROPAGATING BANDS BY AFTN...WITH AN ACCOMPANYING RISK FOR
DMG WIND/MARGINALLY SVR HAIL.

..CORFIDI/GARNER.. 05/06/2012