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 Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. | |
 Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. | |
 Probability of damging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. | |
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SPC AC 230600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED JUN 23 2010
VALID 231200Z - 241200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF
IL/INDIANA/OH/LOWER MI/WI TO WESTERN NY/PA...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE
MIDWEST/SOUTH-CENTRAL PLAINS TO APPALACHIANS/NORTHEAST STATES...
...SYNOPSIS...
WITHIN A PROGRESSIVE BELT OF NORTHERN TIER WESTERLIES...CURRENT
NORTHERN HIGH PLAINS SHORTWAVE TROUGH WILL CONTINUE TO STEADILY
ADVANCE EAST-NORTHEASTWARD ACROSS THE UPPER MIDWEST TODAY AND GREAT
LAKES REGION TONIGHT...AS IT GRADUALLY PHASES WITH A MORE
APPRECIABLE UPPER TROUGH CENTERED NEAR HUDSON BAY. AT THE
SURFACE...A COLD FRONT WILL PROGRESS EAST-SOUTHEASTWARD ACROSS THE
MIDWEST/UPPER GREAT LAKES AND SOUTH-CENTRAL PLAINS...WITH A WARM
FRONT RETREATING NORTHEASTWARD ACROSS THE OH VALLEY/GREAT LAKES
REGION AHEAD OF AN UPPER MS RIVER VALLEY SURFACE LOW/POTENTIAL EARLY
DAY MCS.
...MIDDLE/UPPER MS VALLEY AND MIDWEST/GREAT LAKES REGION...
A MULTI-ROUND/MULTI-MODE SEVERE WEATHER EPISODE IS LIKELY ACROSS THE
REGION TODAY AND TONIGHT. A COMPLEX EARLY DAY SCENARIO IS LIKELY BY
VIRTUE OF SPATIAL/CONVECTIVE INTENSITY UNCERTAINTY REGARDING AN
EARLY DAY MCS...WHICH MAY INDEED STILL BE PRODUCING WIND DAMAGE
ACROSS THE UPPER MS RIVER VALLEY/LAKE MICHIGAN VICINITY EARLY THIS
MORNING. BASED ON THE EXPECTED TIMING/LOCATION OF THIS MORNINGS
ACTIVITY...OBSERVATIONAL/NUMERICAL GUIDANCE EVIDENCE SUGGEST THE
MCS-DOWNSTREAM EASTERN-SOUTHERN PERIPHERAL AIRMASS SHOULD HAVE
OPPORTUNITY TO DESTABILIZE RELATIVELY EARLY IN THE DAY ACROSS
NORTHERN PORTIONS OF IL/INDIANA INTO LOWER MI/NORTHERN OH. THIS MAY
YIELD A SUSTAINED WIND DAMAGE THREAT THROUGH THE MORNING AND/OR
CONTRIBUTE TO A RENEWED SEVERE POTENTIAL IN THESE AREAS BY EARLY
AFTERNOON. WIND DAMAGE WILL LIKELY BE THE PRIMARY CONCERN. SOME
SEVERE HAIL WILL BE POSSIBLE...AND PENDING A SEMI-DISCRETE
SUPERCELLULAR MODE AWAY FROM THE EARLY DAY MCS...SOME TORNADOES WILL
BE POSSIBLE AS WELL.
PERIPHERALLY...AT LEAST ISOLATED THUNDERSTORMS MAY FORM DURING THE
AFTERNOON ALONG THE RETREATING WARM FRONT ACROSS PARTS OF THE UPPER
OH VALLEY INCLUDING OH/WESTERN PA. THESE STORMS WILL BE EMBEDDED
ALONG THE SOUTHERN FRINGE OF 35-40 KT WESTERLY MID-LEVEL FLOW...WITH
LOW-LEVEL TURNING NOTED IN FORECAST SOUNDINGS AND THE POSSIBILITY OF
150-250 MS/S2 OF 0-1 KM SRH. AS SUCH...SUPERCELLS CAPABLE OF SEVERE
HAIL/DAMAGING WINDS AND A FEW TORNADOES WILL BE POSSIBLE.
FARTHER WEST/LATER IN THE AFTERNOON...SUBSEQUENT/SECONDARY ROUND OF
DEEP CONVECTIVE DEVELOPMENT APPEARS LIKELY LATE IN THE AFTERNOON
ACROSS THE MIDWEST/MIDDLE TO UPPER MS VALLEY VICINITY. WITH LOWER TO
MIDDLE 70S F WARM SECTOR DEWPOINTS AND A RELATIVELY STRONG
INSTABILITY FEED FROM THE WEST-SOUTHWEST...AMBIENT AIRMASS SHOULD
RECOVER/DESTABILIZE ESPECIALLY ALONG/SOUTH OF ANY EARLY DAY
MCS-INDUCED OUTFLOW...AND OTHERWISE IN THE WARM SECTOR AHEAD OF THE
EAST-SOUTHEAST ADVANCING COLD FRONT ACROSS THE MIDWEST. UPWARDS OF
3000-4000 J/KG OF WEAKLY CAPPED MLCAPE IS PLAUSIBLE BY PEAK HEATING
WITHIN THE WARM SECTOR. THIS SUBSEQUENT AFTERNOON DEVELOPMENT IS
MOST PROBABLE ACROSS SOUTHEAST IA/NORTHERN MO/NORTHERN IL AND
PERHAPS SOUTHERN WI/LOWER MI TO NORTHERN INDIANA. A COMBINATION OF
WELL-ORGANIZED MULTICELLS/EARLY MODAL SUPERCELLS ARE LIKELY. WHILE
DAMAGING WINDS MAY BE THE MOST PROMINENT THREAT THROUGH THE
PERIOD...LARGE HAIL WILL BE POSSIBLE ESPECIALLY WITH AFOREMENTIONED
SUPERCELLULAR DEVELOPMENT DURING THE AFTERNOON/EARLY EVENING.
FURTHERMORE...EVEN WITH A TENDENCY FOR VEERING LOW LEVEL
FLOW...SUFFICIENT SPEED IN THE LOWEST 1 KM MAY SUPPORT SUFFICIENT
LOW LEVEL SRH FOR SOME TEMPORAL WINDOW FOR A TORNADO OR TWO BEFORE
STORMS CONGEAL ALONG THE EAST-SOUTHEAST ADVANCING COLD FRONT.
AIDED BY A CONTINUED EASTWARD ADVANCEMENT OF THE PARENT SHORTWAVE
TROUGH OVER THE GREAT LAKES REGION AND A STRENGTHENING
WEST-SOUTHWESTERLY LOW LEVEL JET...ACTIVITY WILL LIKELY GROW UPSCALE
INTO ANOTHER MCS DURING THE EVENING. THIS MCS SHOULD RACE EASTWARD
ACROSS SOUTHERN LOWER MI AND NORTHERN PORTIONS OF INDIANA/OH...WITH
CONTINUED DAMAGING WINDS A DISTINCT POSSIBILITY THROUGH THE NIGHT.
ACTIVITY MAY EVENTUALLY REACH THE LOWER GREAT LAKES VICINITY
INCLUDING UPSTATE NY AND PORTIONS OF PA...AND EVENTUALLY WESTERN NEW
ENGLAND OVERNIGHT/EARLY THURSDAY MORNING.
...LOWER MO VALLEY/SOUTH-CENTRAL PLAINS...
WITH THE UPPER RIDGE HOLDING FIRM ACROSS THE SOUTHERN PLAINS...LARGE
SCALE FORCING WILL BE LIMITED WITH WEAK FLOW ALOFT /15-25 KT AT 500
MB/. NONETHELESS...FRONTAL FORCING AND A MOIST/WEAKLY
CAPPED/MODERATELY UNSTABLE BOUNDARY LAYER WILL BE SUFFICIENT FOR
ISOLATED TO SCATTERED STRONG/SEVERE TSTM DEVELOPMENT ALONG/JUST
AHEAD OF THE SOUTHEAST MOVING COLD FRONT. BOUTS OF SEVERE STORMS
CAPABLE OF DAMAGING WINDS/SEVERE HAIL WILL BE POSSIBLE MAINLY LATE
THIS AFTERNOON/EARLY EVENING.
...CENTRAL APPALACHIANS/CAROLINAS THIS AFTERNOON/EARLY EVENING...
PERHAPS AIDED BY A WEAK/REMNANT CONVECTIVELY INDUCED VORT
MAX...SCATTERED TSTMS SHOULD REDEVELOP OVER THE HIGHER TERRAIN OF
THE CENTRAL APPALACHIANS TO PORTIONS OF THE DOWNSTATE CAROLINAS THIS
AFTERNOON. SPORADIC DAMAGING WIND GUSTS WILL POSSIBLE THIS
AFTERNOON/EARLY EVENING.
..GUYER/DEAN/HURLBUT.. 06/23/2010
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