Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 301752
SWODY2
SPC AC 301751

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1251 PM CDT TUE JUN 30 2015

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SOUTHEAST KS AND NORTHEAST
OK THROUGH SOUTHERN MO AND EXTREME NORTHERN AR...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLIGHT RISK
AREA FROM THE LOWER MO VALLEY...EASTERN KS AND NORTHEAST OK TO THE
LOWER OH AND TN VALLEYS TO SOUTHERN APPALACHIANS...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE NORTHEAST
AND NEW ENGLAND STATES...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS EASTERN MT INTO THE
WESTERN DAKOTAS...

...SUMMARY...
ISOLATED TO SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP
ACROSS SOUTHEAST KANSAS AND SOUTHERN MISSOURI BY WEDNESDAY AFTERNOON
AND SPREAD INTO NORTHEAST OKLAHOMA AND FAR NORTHERN ARKANSAS
WEDNESDAY EVENING.  ISOLATED SEVERE STORMS ARE ALSO POSSIBLE BY
WEDNESDAY AFTERNOON FROM EASTERN PENNSYLVANIA TO VERMONT AND NEW
HAMPSHIRE AND SOUTHERN NEW ENGLAND.  SCATTERED STORMS...A FEW
SEVERE...WILL ALSO DEVELOP FROM THE MID MISSISSIPPI VALLEY INTO THE
TENNESSEE VALLEY.  OTHER STORMS...SOME STRONG...WILL EVOLVE ACROSS
THE NORTHERN HIGH PLAINS.

...ERN KS/NERN OK TO MID MS VALLEY INTO TN VALLEY...
RIDGE-TOPPING SHORTWAVE TROUGH...CURRENTLY MOVING THROUGH SOUTHERN
ALBERTA/SASKATCHEWAN PER WATER VAPOR IMAGERY...SHOULD BE LOCATED
ACROSS THE UPPER MIDWEST REGION AT 12Z WEDNESDAY.  THIS RELATIVELY
LOW-AMPLITUDE TROUGH WILL PROGRESS TO THE SOUTHEAST WITHIN
NORTHWESTERLY FLOW ALOFT...MOVING INTO THE MIDWEST AND MID MS VALLEY
BY WEDNESDAY AFTERNOON WITH THE SOUTHERN EXTENT REACHING THE TN
VALLEY WEDNESDAY NIGHT.  FORCING FOR ASCENT WITH THIS FEATURE
COMBINED WITH ONGOING STRONG LOW-LEVEL WAA WITHIN THE NOSE OF A
CENTRAL PLAINS SWLY LLJ SHOULD BE MAINTAINING TSTM COVERAGE ACROSS
PORTIONS OF THE MID AND LOWER MO VALLEY LATE DAY 1 INTO EARLY DAY 2.
ALTHOUGH THIS EARLY DAY 2 LLJ SHOULD VEER AND WEAKEN SOME INTO
WEDNESDAY AFTERNOON...SUFFICIENT LOW-LEVEL WAA IS EXPECTED TO BE
SUPPORTIVE OF NEW TSTM DEVELOPMENT ALONG THE SRN PERIPHERY OF THE
LOWER MO VALLEY MCS AND/OR IN VICINITY OF AN ATTENDANT CONVECTIVE
OUTFLOW BOUNDARY INTO PARTS OF SRN MO AND PERHAPS SOUTHEAST KS.
MODELS ARE IN GENERAL AGREEMENT INDICATING MODERATELY STRONG
INSTABILITY ACROSS THE SLIGHT RISK AREA WITH EFFECTIVE BULK SHEAR OF
40-45 KT FAVORING ORGANIZED CONVECTION INCLUDING SUPERCELLS
WEDNESDAY AFTERNOON INTO THE EVENING.  A SEPARATE SWLY LLJ WILL
STRENGTHEN ACROSS THE SRN PLAINS WITH THE COMBINATION OF WEAK HEIGHT
FALLS AND INCREASING LOW-LEVEL WAA INTO ERN OK/SERN KS AND NRN
AR/SRN MO FAVORING UPSCALE GROWTH OF ONE OR MORE MCS.

FARTHER EAST...A WEAK CAP SHOULD SUPPORT FAIRLY WIDESPREAD
CONVECTIVE DEVELOPMENT EARLY IN THE FORECAST PERIOD ACROSS THE LOWER
OH AND MUCH OF THE TN VALLEYS INTO THE SOUTHERN APPALACHIANS.
COVERAGE OF STRONGER TO SEVERE STORMS SHOULD BE LESS ACROSS THESE
AREAS GIVEN WEAKER BULK SHEAR.

...NERN U.S...
THIS OUTLOOK ISSUANCE MAINTAINS A MARGINAL SEVERE WEATHER RISK
ACROSS PARTS OF THE NORTHEAST STATES...THOUGH PORTIONS OF SOUTHERN
NEW ENGLAND COULD HAVE HIGHER SEVERE PROBABILITIES INTRODUCED IN
SUBSEQUENT OUTLOOKS IF CONFIDENCE IN DESTABILIZATION INCREASES FOR
THAT REGION.  LARGE-SCALE ASCENT IS EXPECTED AHEAD OF A PROGRESSIVE
SHORTWAVE TROUGH EXPECTED TO TRANSLATE INTO THE NRN MID-ATLANTIC
REGION AND HUDSON VALLEY BY 18Z...THEN INTO ERN NEW ENGLAND BY
SUNSET.  THIS ASCENT COMBINED WITH STEEPENING LOW-LEVEL LAPSE RATES
SHOULD SUPPORT SCATTERED TSTMS WITHIN A WARM SECTOR FORECAST TO
DEVELOP ACROSS SRN NEW ENGLAND BY EARLY AFTERNOON.  DEGREE OF
DESTABILIZATION REMAINS A LIMITING FACTOR FOR HIGHER SEVERE
PROBABILITIES AS PRECIPITATION/CLOUDINESS WILL LIKELY BE LOCATED
ACROSS SRN NEW ENGLAND AT THE START OF DAY 2.  SHEAR PROFILES ARE
EXPECTED TO SUPPORT ORGANIZED UPDRAFTS...WITH EVEN MUCAPE OF
500-1000 J/KG SUGGESTING ISOLATED COVERAGE OF STRONG TO SEVERE
STORMS INTO THE AFTERNOON.  ROBUST CONVECTION COULD SPREAD INTO THE
REST OF WRN NEW ENGLAND BY EARLY AFTERNOON...WITH LOCALLY DAMAGING
WINDS BEING THE PRIMARY SEVERE WEATHER THREAT.  HOWEVER...A TORNADO
OR TWO CANNOT BE RULED OUT...AS CURVED LOW-LEVEL HODOGRAPHS COULD
SUPPORT THIS SEVERE HAZARD TOO.

...NRN HIGH PLAINS...
MODELS DIFFER IN THE AMPLITUDE OF A SHORTWAVE TROUGH EXPECTED TO DIG
SEWD FROM SWRN CANADA INTO THE NRN HIGH PLAINS THIS FORECAST PERIOD.
THIS FEATURE SHOULD ENHANCE ASCENT ACROSS THE HIGH PLAINS FROM ERN
MT INTO THE BLACK HILLS REGION OF SD DURING THE AFTERNOON FOCUSING
VERTICAL MOTION ALONG A NW-SE CORRIDOR OF WARM ADVECTION.
BOUNDARY-LAYER LAPSE RATES SHOULD STEEPEN MARKEDLY ALONG WRN FRINGE
OF THIS ZONE...SHARPENING DEMARCATION BETWEEN SOMEWHAT COOLER AIR
MASS OVER THE DAKOTAS.  SHEAR PROFILES FAVOR ORGANIZED DEEP ROTATION
AND WILL MAINTAIN A MARGINAL RISK FOR A SEVERE THREAT OF HAIL/WIND.

..PETERS.. 06/30/2015




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