April 30-May 5 Plains/MW/OV Severe Weather, SPC Risk Level: Day 1-3 Slight Risk - Forecasts & OBS Options

[WeatherMonger]

And of course the storm weakens when I see it. Barely any lightning in the distance now. More so with the second one but I have to be up in 4 hours

This post has been edited by WeatherMonger: May 5 2012, 01:15 AM

[Snow____]

Looks like all the good storms are going to be sliding of just to my south. Perfect. Well. Hitting the sack. Maybe I'll get woken up with some boomers. That'll be great.

[WeatherMonger]

New Day 1 added hatchig to the 10% tornado risk

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 AM CDT SAT MAY 05 2012

VALID 051300Z - 061200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVR PARTS OF THE NRN PLNS AND
UPR MS VLY...

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

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF TX...

...SYNOPSIS...
CLOSED LOW NOW OVER NW MT WILL PROGRESS E TO SRN SK THIS PERIOD AS
ATTENDANT TROUGH REACHES THE NRN HI PLNS/ERN GRT BASIN. AHEAD OF
THE MAIN TROUGH...SATELLITE AND UPR AIR ANALYSES SHOW A STREAM OF
ENHANCED SWLY FLOW WITH EMBEDDED SMALL-SCALE DISTURBANCES ATTM
EXTENDING FROM ERN UT AND WY INTO THE WRN DAKOTAS. THIS BELT OF
ENHANCED FLOW SHOULD SHIFT EWD ACROSS THE NRN PLNS TODAY...AHEAD OF
THE MAIN TROUGH...AS BROAD RIDGE CONTINUES OVER THE MID MS AND OH
VLYS.

AT THE SFC...WRN PART OF DIFFUSE FRONT ATTM EXTENDING FROM THE
NEB/SD BORDER AREA ESE INTO THE LWR OH VLY EXPECTED TO EDGE NWD
INTO SRN/ERN SD AND FAR SRN MN TODAY...WITH A WEAK TRIPLE POINT LOW
FORMING OVER N CNTRL NEB. LATER TODAY AND TNGT...A COLD FRONT
SHOULD BECOME BETTER DEFINED OVER THE NRN HI PLNS. THIS FEATURE
WILL THEN SWEEP E/SE ACROSS THE NRN/CNTRL PLNS...WITH A WEAK SFC LOW
CONTINUING E ACROSS THE MID MO VLY/UPR MIDWEST.

ELSEWHERE...AN UPR LVL IMPULSE NOW OVER BAJA CA SHOULD PROGRESS NE
TOWARD THE TX BIG BEND BY LATE AFTN...WITH THE SFC DRYLINE EXTENDING
FROM WRN OK TO THE EDWARDS PLATEAU. FARTHER E...WEAK UPR
DISTURBANCE NOW OVER E TX SHOULD TRACK ESE ACROSS THE LWR MS VLY.

...N CNTRL STATES TODAY/TNGT...
REGION INVOF AFOREMENTIONED FRONT AND OUTFLOW BOUNDARIES OVER SRN
SD....NRN/ERN NEB...NW IA...AND SW MN WILL BE BECOME VERY UNSTABLE
AS 60S SFC DEW POINTS OVERSPREAD REGION BENEATH STEEP MID LVL LAPSE
RATES...WITH LATE AFTN SBCAPE EXPECTED TO RANGE FROM 2000 TO 4000
J/KG.

CONTINUED EWD ADVANCE OF LEAD UPR LVL DISTURBANCES AHEAD OF MAIN WRN
STATES TROUGH...AND SUBSTANTIAL DEGREE OF VERTICAL VEERING IN THE
WIND PROFILES...WILL RESULT IN HODOGRAPHS VERY FAVORABLE FOR
ROTATING STORMS...ESPECIALLY E OF THE TRIPLE POINT LOW ALONG THE
QSTNRY/WARM FRONT. AT LEAST ISOLD TSTM DEVELOPMENT APPEARS LIKELY
THERE...AND ALSO FARTHER W INTO THE BLACK HILLS DURING MID-LATE
AFTN. RAPID GROWTH INTO SUPERCELLS CAPABLE OF VERY LARGE HAIL AND
TORNADOES MAY OCCUR...ESPECIALLY OVER NERN NEB/SE SD INTO PARTS OF
NW IA AND FAR SW MN. AS THE COLD FRONT
ACCELERATES E/SE ACROSS THE NRN/CNTRL PLNS TNGT...UPSCALE
DEVELOPMENT INTO ONE OR MORE MCSS APPEARS LIKELY. THESE MAY POSE A
GRADUALLY DIMINISHING SVR THREAT EWD IN THE UPR MS VLY AND SWD INTO
THE MID MO VLY EARLY SUN.

...PARTS OF CNTRL AND SRN TX THIS AFTN/EVE...
STRONG TO EXTREME INSTABILITY WILL ONCE AGAIN DEVELOP WITH AFTN
HEATING E OF DRYLINE IN CNTRL AND SRN TX...WITH 700-500 MB LAPSE
RATES NEAR 9 C/KM. COUPLED WITH APPROACH OF UPR LVL IMPULSE...SETUP
MAY YIELD ISOLD LATE DAY TSTMS ALONG AND POSSIBLY AHEAD OF DRYLINE.
INTENSITY/COVERAGE SHOULD BE SOMEWHAT LESS THAN YESTERDAY OWING TO
WEAKER MID LVL WLYS. BUT 25-30 KT WNWLY DEEP SHEAR COULD FOSTER A
FEW SUPERCELLS/SUSTAINED STORMS WITH LARGE HAIL/LOCALLY DMGG WIND
GIVEN STRONG BUOYANCY.

...GA/SC/SRN NC THIS AFTN...
FAIRLY STRONG DIURNAL DESTABILIZATION /WITH INCREASING TO SBCAPE TO
2000 J PER KG/ SHOULD OCCUR OVER PARTS OF GA...SC...AND NC TODAY
AHEAD OF OVERNIGHT CONVECTIVE SYSTEMS IN THE OH/TN VLYS. COUPLED
WITH PRESENCE OF MODERATE WNWLY MID LVL FLOW AND ERN EXTENSION OF
EML PLUME...ENVIRONMENT COULD SUPPORT REDEVELOPMENT OF STRONG TO
POSSIBLY SVR PULSE STORMS THIS AFTN OVER PIEDMONT PORTIONS OF GA/SC
AND NC. FCST WIND PROFILES AND THE PRESENCE OF EXITING OUTFLOW
BOUNDARIES TO FOCUS LOW LVL UPLIFT SUGGEST THE POSSIBILITY FOR
DEVELOPMENT OF FORWARD-PROPAGATING/SE-MOVING BANDS OF STORMS THAT
COULD YIELD DMGG WIND/SVR HAIL THROUGH EARLY EVE.

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

[WeatherMonger]

MESOSCALE DISCUSSION 0714
NWS STORM PREDICTION CENTER NORMAN OK
0209 PM CDT SAT MAY 05 2012

AREAS AFFECTED...CNTRL/NERN NEB...SERN SD...NWRN IA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 051909Z - 052045Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...TORNADO WATCH WILL BE NEEDED TO ADDRESS THE DEVELOPING
SEVERE THREAT FROM CNTRL/NERN NEB...NEWD INTO NWRN IA. THIS WATCH
WILL LIKELY BE ISSUED BY 21Z.

DISCUSSION...EARLY MORNING MCS ACTIVITY THAT SPREAD ACROSS SD INTO
MN HAS REINFORCED A BOUNDARY THAT CURRENTLY EXTENDS FROM CNTRL NEB
INTO THE NWRN CORNER OF IA. WHILE THIS BOUNDARY MAY CONTINUE TO SAG
SWD ACROSS PARTS OF NRN IA...STRONG HEATING OVER NEB WILL LIKELY
PREVENT ANY FURTHER SWD PUSH ACROSS THE CNTRL PLAINS. WARM SECTOR
CU FIELD APPEARS TO BE EXPANDING AND CHANGING CHARACTER ACROSS NERN
NEB INTO NWRN IA PER DEEPENING BOUNDARY LAYER. IN ALL LIKELIHOOD
THUNDERSTORMS WILL EVOLVE ALONG THE WIND SHIFT INITIALLY ACROSS NEB
AS LOW LEVEL LAPSE RATES ARE SOMEWHAT STEEPER ACROSS THIS REGION.
NEEDLESS TO SAY EXTREME INSTABILITY...SBCAPE IN EXCESS OF 4000
J/KG...AND DEEP LAYER SHEAR MORE THAN ADEQUATE TO SUPPORT ROTATING
UPDRAFTS...WILL PROVE CONDUCIVE FOR SUPERCELLS...POTENTIALLY
TORNADIC. VERY LARGE HAIL IS ALSO POSSIBLE WITH THIS ACTIVITY AND A
WATCH WILL BE ISSUED BY 21Z.

..DARROW.. 05/05/2012


ATTN...WFO...DMX...FSD...OAX...GID...LBF...

LAT...LON 41259972 42769775 43189498 42339381 41469641 40599852
41259972

[snowlover2]

Holding off until about 0z for tornado watch.

MESOSCALE DISCUSSION 0716
NWS STORM PREDICTION CENTER NORMAN OK
0352 PM CDT SAT MAY 05 2012

AREAS AFFECTED...CNTRL-NERN NEB / SERN SD / NWRN IA

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 052052Z - 052215Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...SUPERCELLS CAPABLE OF TORNADOES...VERY LARGE HAIL...AND
DAMAGING WIND GUSTS ARE EXPECTED TO DEVELOP PRIOR TO 00Z...REQUIRING
A TORNADO WATCH.

DISCUSSION...20Z SURFACE ANALYSIS SHOWED A SURFACE LOW W OF MCK WITH
AN ASSOCIATED STATIONARY BOUNDARY EXTENDING NEWD TO N OF OFK AND SUX
BEFORE CURVING SEWD THROUGH CNTRL IA. AIR MASS ALONG AND S OF THIS
BOUNDARY HAS WARMED INTO THE UPPER 80S-LOWER 90S AND WHEN COUPLED
WITH DEWPOINTS IN THE MID-UPPER 60S...IS RESULTING IN MLCAPE VALUES
OF 3000-4000 J/KG AND A WEAKENING CAP. THOUGH LOW-LEVEL WAA
PERSISTS...MIDLEVEL HEIGHTS APPEAR TO BE STILL SLIGHTLY RISING AHEAD
OF NRN ROCKIES UPPER TROUGH. AS SUCH...IT NOW APPEARS THAT STORM
INITIATION MAY BE DELAYED TO CLOSER TO 00Z WHEN CONVERGENCE
INCREASES IN THE EXIT REGION OF A STRENGTHENING LLJ.

PRONOUNCED VEERING OF WINDS WITH HEIGHT AND STRENGTHENING LOW AND
DEEP-LAYER SHEAR WILL SUPPORT THE RAPID EVOLUTION OF STORMS INTO
SUPERCELLS WITH AN ASSOCIATED THREAT FOR TORNADOES...VERY LARGE HAIL
AND DAMAGING WINDS.

A TORNADO WATCH WILL BE REQUIRED PRIOR TO 00Z.

[WeatherMonger]

If it can hold it's own and doesn't try to dive more south than east, East Dubzz could get in on this one

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE LA CROSSE WI
429 PM CDT SAT MAY 5 2012

THE NATIONAL WEATHER SERVICE IN LA CROSSE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EASTERN FLOYD COUNTY IN NORTH CENTRAL IOWA...
  WESTERN CHICKASAW COUNTY IN NORTHEAST IOWA...

* UNTIL 530 PM CDT

* AT 424 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM LOCATED NEAR CHARLES CITY...MOVING SOUTHEAST AT
  25 MPH. THIS STORM CAN PRODUCE LARGE DAMAGING HAIL UP TO GOLF BALL 
  SIZE AND DAMAGING WINDS IN EXCESS OF 60 MPH. TRAINED SPOTTERS      
  REPORTED GOLF BALL SIZE HAIL NEAR THE FLOYD COUNTY FAIRGROUNDS IN  
  CHARLES CITY. THIS WARNING EXTENDS THE PREVIOUS SEVERE             
  THUNDERSTORM WARNING FOR FLOYD AND CHICKASAW   COUNTIES.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  MIDWAY AND CARRVILLE AROUND 435 PM...
  HOWARDS WOOD RECREATIONAL AREA AND BASSETT AROUND 440 PM...
  NASHUA AND BRADFORD AROUND 445 PM...
  IONIA AND HIGHWAY 18 AND COUNTY V 18 AROUND 450 PM...  
  NEW HAMPTON AND WILLIAMSTOWN AROUND 505 PM...
  BOYD AROUND 510 PM...

[snowlover2]

And it begins.

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 251
NWS STORM PREDICTION CENTER NORMAN OK
535 PM CDT SAT MAY 5 2012

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

EXTREME NORTHWEST IOWA
CENTRAL AND NORTHEAST NEBRASKA
EXTREME SOUTHEAST SOUTH DAKOTA

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 535 PM UNTIL
1100 PM CDT.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 35 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 50 MILES WEST SOUTHWEST OF
BROKEN BOW NEBRASKA TO 35 MILES NORTH NORTHEAST OF SIOUX CITY
IOWA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED
WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

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 248...WW 249...WW 250...

DISCUSSION...STRONG SURFACE HEATING/DEEP MIXING IN THE WARM SECTOR
HAS REDUCED CONVECTIVE INHIBITION ACROSS NEB...AND VISIBLE IMAGERY
IS BEGINNING TO SHOW DEEPENING CUMULUS ALONG THE SURFACE FRONT FROM
SE OF LBF TO SW OF YKN. THE SITUATION IS COMPLICATED BY LOWER
DEWPOINTS IN THE WARM SECTOR AND A QUICK TRANSITION TO STRONGER
SHEAR/COOLER TEMPERATURES ACROSS THE FRONT...LEAVING ONLY A NARROW
CORRIDOR WITH SURFACE-BASED SUPERCELL/TORNADO POTENTIAL.
STILL...THE ORIENTATION OF THE FRONT APPEARS TO BE ROUGHLY PARALLEL
TO EXPECTED STORM MOTION...SO ANY STORMS THAT FORM ALONG THE
IMMEDIATE SURFACE FRONT COULD REMAIN IN THE NARROW FAVORABLE
CORRIDOR LONG ENOUGH TO BE A TORNADO THREAT. IN ADDITION TO THE
TORNADO RISK...VERY LARGE HAIL WILL BE POSSIBLE WITH ANY SUSTAINED
STORMS THROUGH LATE EVENING.

[snowlover2]

MESOSCALE DISCUSSION 0721
NWS STORM PREDICTION CENTER NORMAN OK
0621 PM CDT SAT MAY 05 2012

AREAS AFFECTED...PARTS OF N CNTRL NEB...SERN SD...SWRN MN...NWRN IA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 052321Z - 060045Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...SEVERE STORMS ARE EXPECTED TO RAPIDLY INCREASE IN NUMBER
AND INTENSITY EARLY THIS EVENING...WITH A RISK FOR LARGE HAIL THE
PRIMARY INITIAL THREAT THROUGH 01-03Z.

DISCUSSION...ISOLATED VIGOROUS CONVECTIVE DEVELOPMENT ALREADY
APPEARS UNDERWAY ACROSS SOUTHEASTERN SOUTH DAKOTA...NORTH OF A
FAIRLY SHARP SURFACE FRONTAL ZONE THAT HAS ADVANCED SOUTH OF BROKEN
BOW AND NORTH PLATTE...WHILE REMAINING QUASI-STATIONARY NORTH OF
NORFOLK THROUGH THE SIOUX CITY AREA...ON INTO CENTRAL IOWA. THIS IS
BEING SUPPORTED BY LOW-LEVEL WARM ADVECTION...AND LIFT OF MOIST
PARCELS TO LEVELS OF FREE CONVECTION...ABOVE THE FIRMLY ENTRENCHED
COOL/STABLE NEAR SURFACE LAYER. EVEN TO THE NORTH OF THE
FRONT...ACROSS MUCH SOUTHERN/EASTERN SOUTH DAKOTA...WARM ELEVATED
MIXED LAYER AIR HAS BEEN TENDING TO INHIBIT CONVECTIVE DEVELOPMENT.
HOWEVER...INHIBITION APPEARS LIKELY TO WEAKEN BY THE 01-03Z TIME
FRAME...IF NOT BEFORE...AIDED BY INCREASING LARGE-SCALE MID-LEVEL
FORCING DOWNSTREAM OF THE UPPER TROUGH LIFTING ACROSS THE NORTHERN
ROCKIES...PERHAPS AIDED BY RADIATIVE PROCESSES. AS THIS OCCURS...A
RAPID INCREASING IN STORM DEVELOPMENT APPEARS LIKELY IN THE PRESENCE
OF STRONG CONVECTIVE LAYER SHEAR AND MOST UNSTABLE CAPE UP TO
2000-4000 J/KG. LARGE HAIL SHOULD BE THE PRIMARY THREAT
INITIALLY...BEFORE ACTIVITY BEGINS TO CONSOLIDATE LATER THIS
EVENING.