National Weather Service Raw Text Product

317 
ACUS01 KWNS 221255
SWODY1
SPC AC 221254

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0754 AM CDT MON JUN 22 2015

VALID 221300Z - 231200Z

...THERE IS AN ENH RISK OF SVR TSTMS OVER A PART OF THE UPPER
MIDWEST AND UPPER GREAT LAKES REGION...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ENH RISK FROM
THE UPPER MS AND LOWER MO VALLEYS EWD THROUGH THE GREAT LAKES...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK FROM
THE UPPER MS AND LOWER MO VALLEYS EWD THROUGH THE GREAT LAKES...

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

...SUMMARY...
SEVERE STORMS CAPABLE OF INTENSE...DAMAGING OUTFLOW WINDS...STRONG
TORNADOES AND VERY LARGE HAIL ARE PROBABLE OVER THE UPPER MIDWEST
AND GREAT LAKES REGION TODAY THROUGH TONIGHT.

...SYNOPSIS...

A POLAR-BRANCH SHORT-WAVE TROUGH FROM MANITOBA INTO THE DAKOTAS WILL
AMPLIFY AND GRADUALLY ASSUME A SLIGHT NEGATIVE TILT AS IT TRANSLATES
THROUGH THE GREAT LAKES AND ONTARIO.  THIS SYSTEM WILL BE ATTENDED
BY A 70-80 KT MID-LEVEL JET STREAK AND CORRIDOR OF 50-100 M/12-HR
HEIGHT FALLS AT 500 MB WHICH WILL OVERSPREAD THE GREAT LAKES LATER
TODAY INTO TONIGHT.  

AT THE SURFACE...AN ASSOCIATED AREA OF LOW PRESSURE WILL DEEPEN
WHILE DEVELOPING FROM SWRN MN INTO ERN ONTARIO/WRN QUEBEC BY
12Z/TUESDAY.  A WARM FRONT WHICH WILL BE MODULATED BY CONVECTIVE
OUTFLOW ATTENDANT TO EARLY-DAY STORMS WILL ATTEMPT TO MOVE NWD INTO
THE GREAT LAKES WHILE A TRAILING COLD FRONT SWEEPS EWD THROUGH THE
UPPER MS VALLEY AND UPPER GREAT LAKES.  THE TRAILING EXTENSION OF
THIS FRONT WILL MOVE MORE SLOWLY SEWD THROUGH THE MID/LOWER MO
VALLEY AND CNTRL PLAINS. 

...UPPER MIDWEST EWD THROUGH THE GREAT LAKES AND NRN OH VALLEY...

A COMPLEX-STRUCTURED MCS ONGOING OVER SRN MN/NRN IA WILL CONTINUE
EWD ALONG THE SYNOPTIC WARM FRONT THROUGH PORTIONS OF CNTRL/SRN WI
AND NRN IL THIS MORNING...AND EVENTUALLY INTO LOWER MI BY AFTERNOON.
 THIS SYSTEM HAS A WELL-DEFINED MCV WITH THE FSD VAD INDICATING
60-80 KT WINDS WITHIN THE DESCENDING REAR-INFLOW JET AT 1 KM AGL. 
GIVEN THE VERY MOIST AND MODERATELY UNSTABLE AIR MASS FEEDING INTO
THIS SYSTEM ALONG A 40-50+ KT SWLY LLJ...EXPECT DAMAGING WIND
POTENTIAL TO PERSIST...AND POSSIBLY INCREASE LATER TODAY AS THE
BOUNDARY LAYER WARMS AND DESTABILIZES.

DUE TO THE EXPANSIVE COLD POOL GENERATED BY THE MCS...CONSIDERABLE
UNCERTAINTY REMAINS WITH REGARD TO THE INTENSITY AND LOCATION OF
DIURNALLY ENHANCED TSTM DEVELOPMENT THIS AFTERNOON.  A NUMBER OF
CONVECTION-ALLOWING MODELS SUGGEST THAT STORMS WILL REDEVELOP BY
EARLY AFTERNOON ALONG THE COLD FRONT FROM PORTIONS OF W-CNTRL WI
INTO N-CNTRL/NERN IA AS LARGE-SCALE FORCING FOR ASCENT/DCVA
OVERSPREADS THE AREA.  WHILE THE CHARACTER OF THE THERMODYNAMIC
ENVIRONMENT REMAINS UNCLEAR...BOTH LOW-LEVEL AND DEEP-LAYER SHEAR
WILL BE QUITE STRONG /I.E. EFFECTIVE VALUES OF BULK SHEAR AND SRH OF
50-60 KT AND 300-400 M2 PER S2...RESPECTIVELY/  AND SUPPORTIVE OF
SUPERCELLS CAPABLE OF LARGE HAIL AND TORNADOES /SOME POSSIBLY
STRONG/...NAMELY OVER CNTRL/SRN WI INTO NERN IA AND NRN IL.

OTHER STORMS MAY DEVELOP LATER TODAY FROM THE VICINITY OF THE COLD
FRONT EWD ALONG THE OUTFLOW BOUNDARY TRAILING THE EARLY-DAY MCS FROM
PORTIONS OF IA INTO NRN IL. AND WHILE A FAVORABLE OVERLAP OF
3000-4000+ J/KG MLCAPE AND STRONG VERTICAL SHEAR WILL
EXIST...PRONOUNCED CAPPING /SEE THE 12Z OAX SOUNDING/ MAY BECOME
PROBLEMATIC TO STORM DEVELOPMENT...ESPECIALLY IF THE BOUNDARY
CONTINUES TO SETTLE SWD.  AS SUCH...A CONDITIONAL RISK FOR
SUPERCELLS CAPABLE OF VERY LARGE HAIL...A FEW TORNADOES AND DAMAGING
WINDS WILL EXIST GIVEN DIURNAL STORM DEVELOPMENT AND SUSTENANCE.

BY THIS EVENING...ONGOING STORMS ALONG THE COLD FRONT MAY
CONSOLIDATE INTO A MIXED-MODE MCS /I.E. EMBEDDED SUPERCELLS AND
BOWS/ WITH THE THREAT FOR DAMAGING WINDS...LARGE HAIL AND POSSIBLY A
TORNADO OR TWO SPREADING SEWD ACROSS CNTRL/SRN LOWER MI AND PORTIONS
OF IL...IND...OH.  THIS MCS MAY AFFECT PARTS OF THE LOWER GREAT
LAKES LATE TONIGHT INTO EARLY TUESDAY.

AN UPGRADE TO A MODERATE RISK REMAINS POSSIBLE IN LATER DAY ONE
OUTLOOKS...ONCE MESOSCALE DETAILS REGARDING THE DESTABILIZATION
PROCESS IN THE WAKE OF THE MCS BECOME MORE CLEAR.

...SERN STATES THIS AFTERNOON/EVENING...

HEATING ALONG THE HIGH TERRAIN AND CONVERGENCE ALONG RESIDUAL
OUTFLOW BOUNDARIES WILL GIVE RISE TO SCATTERED AFTERNOON STORMS
AMIDST A VERY MOIST AND MODERATELY UNSTABLE AIR MASS.  VERTICAL
SHEAR WILL BE WEAK...BUT CONSIDERABLE WATER LOADING OF CONVECTIVE
DOWNDRAFTS AND RESULTANT RISK FOR ISOLATED DAMAGING SURFACE WINDS.

..MEAD/MOSIER.. 06/22/2015