Chase 2011 - Day 31 Discussion

[Paul Sherman]

Decisions, Decisions........ :lol: - MODERATE RISK!

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0739 AM CDT MON MAY 30 2011

VALID 301300Z - 311200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY

TONIGHT FROM CENTRAL NEB TO ERN SD...WRN MN...AND EXTREME SE ND...

...THERE IS A SLGT RISK OF SVR TSTMS FROM MN TO THE CENTRAL KS/OK

BORDER...

...NRN PLAINS THROUGH TONIGHT...

A DEEP MIDLEVEL TROUGH NOW APPROACHING THE CENTRAL ROCKIES WILL

EJECT NEWD TO THE NRN PLAINS TONIGHT...ACCOMPANIED BY A 70-90 KT

SSWLY 500 MB JET CORE. AN INITIAL REMNANT LEE CYCLONE NOW OVER

CENTRAL NEB WILL DEVELOP NNEWD TO THE ERN DAKOTAS...WHILE A

SECONDARY LEE CYCLONE IS MAINTAINED INVOF SW NEB THIS AFTERNOON. E

OF THE INITIAL CYCLONE...A WARM FRONT WILL CONTINUE TO MOVE

NWD...ALLOWING THE UNSTABLE WARM SECTOR TO SPREAD NWD INTO NRN MN/WI

BY LATE AFTERNOON. N OF THE WARM FRONT THIS MORNING...ONGOING

ELEVATED STORMS OVER ERN ND/MN/NW WI WILL CONTINUE TO SPREAD NEWD

WITH THE STRONGER LOW-LEVEL WAA...AND THE STRONGER STORMS WILL BE

CAPABLE OF PRODUCING ISOLATED LARGE HAIL.

AFTERNOON WARM SECTOR TEMPERATURES WELL INTO THE 80S AND BOUNDARY

LAYER DEWPOINTS IN THE MID-UPPER 60S WILL CONTRIBUTE TO MLCAPE OF

2500-3000 J/KG. A WARM EML ATOP THE WARM SECTOR BOUNDARY LAYER WILL

CONFINE AFTERNOON CONVECTIVE INITIATION TO A NARROW ZONE ALONG THE

SURFACE COLD FRONT FROM CENTRAL NEB NNEWD INTO THE ERN DAKOTAS.

STORMS WILL FIRST FORM AFTER 21Z IN CENTRAL NEB...JUST NE OF THE

WARMEST SURFACE TEMPERATURES AND STEEPEST LOW-LEVEL LAPSE RATES.

CONVECTION WILL THEN DEVELOP NNEWD ALONG THE SURFACE FRONT ACROSS

ERN SD AND SE ND/WRN MN THROUGH THE EVENING.

THE COMBINATION OF MODERATE-STRONG INSTABILITY AND EFFECTIVE BULK

SHEAR IN EXCESS OF 50 KT WILL FAVOR SUPERCELLS WITH THE INITIAL

STORM DEVELOPMENT. HOWEVER...DEEP-LAYER FLOW/SHEAR VECTORS LARGELY

PARALLEL TO THE FRONT AND PERSISTENT FORCING FOR ASCENT BOTH SUGGEST

THAT UPSCALE GROWTH INTO A SQUALL LINE WILL OCCUR RATHER QUICKLY

AFTER STORM INITIATION. THUS...THE THREAT FOR VERY LARGE HAIL WILL

PEAK IN THE FIRST 2-3 HOURS AFTER INITIATION. THE THREAT FOR

DAMAGING WINDS WILL INCREASE AS THE STORMS GROW UPSCALE INTO A

LINE...WITH THE LIKELIHOOD FOR EMBEDDED BOWS MOVING QUICKLY NNEWD

ALONG THE LINE WITH THE POTENTIAL TO PRODUCE SIGNIFICANT WIND

DAMAGE. A FEW TORNADOES WILL BE POSSIBLE WITH BOTH THE MORE

DISCRETE SUPERCELLS EARLY ACROSS CENTRAL NEB...AS WELL AS WITH THE

BOWING SEGMENTS LATER IN THE CONVECTIVE EVOLUTION FARTHER N INTO ERN

SD AND WRN MN THIS EVENING.

[nsrobins]

NC NE for me. Three hour window for discrete supercell development with impressive 70 - 75kn 5H jet over high dps and really twisted low-level shear. All values point to some strong tornados before the whole system lines-out.

O'Neill, NE

Edited May 30, 2011 by nsrobins

[D-J-V]

WE ARE GOING TO SMASH IT TODAY!

[Arron]

Oh yes Dave!

Heading to O'Neill, NE for some lunch and to take a check on tings!

[craig1uk]

MD issued :

MESOSCALE DISCUSSION 1029

NWS STORM PREDICTION CENTER NORMAN OK

0140 PM CDT MON MAY 30 2011

AREAS AFFECTED...CENTRAL NEB/EASTERN SD INTO SOUTHEAST ND/WESTERN MN

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 301840Z - 302015Z

SEVERE/TORNADO THREAT IS EXPECTED TO INCREASE THROUGH LATE

AFTERNOON/EARLY EVENING...PERHAPS INITIALLY ACROSS

WEST-CENTRAL/NORTH-CENTRAL NEB INTO SOUTHEAST SD. ONE OR MORE

TORNADO WATCHES WILL BE NEEDED BY MID AFTERNOON /LIKELY BY 20Z/.

18Z SUBJECTIVE SURFACE ANALYSIS REFLECTS A 996 MB SURFACE LOW ACROSS

EASTERN SD BETWEEN HURON AND ABERDEEN...WITH A COLD FRONT EXTENDING

SOUTHWESTWARD FROM THE LOW INTO WESTERN NEB NEAR/WEST OF NORTH

PLATTE...WITH EARLY AFTERNOON VISIBLE SATELLITE IMAGERY REFLECTING

AN INCREASING SURFACE BASED CU FIELD NEAR/JUST EAST OF THE COLD

FRONT /ESPECIALLY ACROSS NEB/. WITH STRONGER DPVA/IMPLIED ASCENT NOW

BEGINNING TO OVERSPREAD THE NORTH-CENTRAL HIGH PLAINS...AN INCREASE

IN DEEP CONVECTION IS EXPECTED IN VICINITY OF THE FRONTAL ZONE BY

MID/LATE AFTERNOON...WITH AN ASSORTMENT OF NUMERICAL GUIDANCE

/INCLUDING EXPERIMENTAL HRRR/ INDICATIVE OF DEEP CONVECTION AS EARLY

AS 20-21Z.

AFOREMENTIONED ASCENT COUPLED WITH AMPLE PRE-FRONTAL HEATING AND

MIDDLE/UPPER 60S F SURFACE DEWPOINTS WILL CONTRIBUTE TO WEAKENING

CINH AMID MODERATE INSTABILITY. IN CONJUNCTION WITH A

STRENGTHENING/BUT LARGELY UNIDIRECTIONAL WIND FIELD...INITIAL MODAL

SUPERCELLS CAPABLE OF SOME TORNADOES/LARGE HAIL ARE LIKELY. STORMS

SHOULD ULTIMATELY CONGEAL THROUGH EARLY/MID EVENING...WITH MORE OF A

WIDESPREAD DAMAGING WIND THREAT EVOLVING AS WELL.

..GUYER.. 05/30/2011

[Arron]

Just had lunch in O'Neills, NE which John was VERY happy about :lol: Going to head north from here to the South Dakota border. Things going to start quickly!

[chionomaniac]

Tornado watch issued now - lets hope tour 3 can end on a bang!

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 402

NWS STORM PREDICTION CENTER NORMAN OK

210 PM CDT MON MAY 30 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF

EXTREME SOUTHWEST MINNESOTA

CENTRAL AND NORTHEAST NEBRASKA

SOUTHEAST SOUTH DAKOTA

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 210 PM UNTIL 900

PM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH NORTHWEST OF

BROOKINGS SOUTH DAKOTA TO 40 MILES EAST SOUTHEAST OF MCCOOK

NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).

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.

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO DEVELOP SOON ALONG THE

COLD FRONT EXTENDING ACROSS CENTRAL NEB AND SOUTHEAST SD. THESE

STORMS WILL TRACK QUICKLY NORTHEASTWARD ACROSS THE WATCH AREA

THROUGH EARLY EVENING. INCREASINGLY STRONG SOUTHERLY LOW LEVEL

WINDS AHEAD OF THE STORMS AND MODERATE INSTABILITY WILL PROMOTE A

FEW SUPERCELL STORMS CAPABLE OF VERY LARGE HAIL AND TORNADOES.

OTHERWISE...EVOLUTION TO A SQUALL LINE IS EXPECTED WITH INCREASING

RISKS OF DAMAGING WINDS THROUGH THE EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 24040.

[Arron]

Heading towards the storm just south of Barrett, NE. Should intercept on the South Dakota border

[nsrobins]

Dunning cell backbuidling. Nice updraft scud on Eric Trease cam.