SPC AC 150606
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0106 AM CDT MON JUN 15 2009
VALID 151200Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS MUCH OF THE PLAINS TO THE
CAROLINAS...
...SYNOPSIS...
BROAD UPPER RIDGE WILL REMAIN OVER TX/NORTHERN MEXICO AND GULF COAST
REGION...WHILE MULTIPLE MID LEVEL DISTURBANCES CONTINUE TO EJECT
EAST-NORTHEASTWARD ACROSS THE PLAINS/MIDWEST AHEAD OF AN UPPER
TROUGH DIGGING ALONG THE CA COAST TOWARD BAJA. MULTIPLE WEST-EAST
SURFACE BOUNDARIES...VIA LINGERING SYNOPTIC FRONT AND RESIDUAL
OUTFLOWS...WILL EXIST ACROSS THE PLAINS...TO A WNW-ESE ORIENTED
FRONTAL ZONE ACROSS THE MIDDLE MS VALLEY AND CAROLINAS/SOUTHEAST
STATES. SIMILAR TO SUNDAY...WITH LITTLE FLUCTUATION WITH THE OVERALL
LARGE SCALE PATTERN TODAY...THIS WILL AGAIN SET THE STAGE FOR A
SEVERE RISK ACROSS A BROAD EXTENT FROM THE PLAINS TO THE SOUTHEAST
STATES/CAROLINAS...WITH OTHER MORE ISOLATED STRONG TSTMS POSSIBLE
ACROSS PORTIONS OF THE NORTHEAST STATES.
...LOWER MO VALLEY/MIDDLE MS VALLEY TO TN VALLEY/SOUTHEAST STATES...
COMPLICATED SCENARIO TODAY...BUT IT APPEARS THAT ONE OR MORE
CLUSTERS OF TSTMS WILL BE ONGOING AT THE BEGINNING OF THE PERIOD
ACROSS THE OZARKS/LOWER MO VALLEY TO THE MIDDLE MS VALLEY VICINITY
ON THE NORTHERN PERIPHERY OF THE SOUTHERN STATES RIDGE. ALONG WITH
POTENTIAL FOR ONE OR MORE MCV/S AND ONGOING SEMI-ORGANIZED TSTM
CLUSTERS EARLY IN THE DAY...A VEERING LOW LEVEL JET AND ASSOCIATED
INSTABILITY FEED FROM THE WEST/SOUTHWEST MAY MAINTAIN THESE TSTMS
INTO THE AFTERNOON...WITH A DIURNAL UPSWING IN COVERAGE/INTENSITY
PROBABLE COINCIDENT WITH A REMNANT NORTHWEST-SOUTHEAST ORIENTED
FRONTAL BOUNDARY/INSTABILITY AXIS. AS SUCH...STORMS MAY GROW UPSCALE
INTO ONE OR MORE MCS/S DURING THE DAY BENEATH A MODERATE BELT OF
WEST-NORTHWESTLY FLOW ALOFT...WITH THESE EAST-SOUTHEAST MOVING
CLUSTERS CAPABLE OF WIND DAMAGE/SOME HAIL POTENTIAL.
...PLAINS THIS AFTERNOON/EVENING...
AN EARLY DAY SEVERE THREAT IS POSSIBLE ACROSS PORTIONS OF THE
MIDDLE/LOWER MO VALLEY...BUT OTHERWISE A MORE APPRECIABLE SEVERE
RISK SHOULD DEVELOP ACROSS THE PLAINS BY MID/LATE AFTERNOON INTO
EARLY EVENING AS MULTIPLE MID LEVEL DISTURBANCES CROSS THE CENTRAL
PLAINS COINCIDENT WITH A RATHER MOIST/UNSTABLE BOUNDARY
LAYER...ESPECIALLY ACROSS THE CENTRAL PLAINS. AMPLE INSTABILITY AND
A BELT OF 40+ KT SOUTHWESTERLY FLOW ALOFT...STRONGEST ACROSS THE
CENTRAL PLAINS...WILL SUPPORT SUPERCELLS CAPABLE OF LARGE HAIL AND
SOME TORNADOES. INITIAL DEVELOPMENT SEEMS PROBABLE ACROSS THE NORTH
CENTRAL HIGH PLAINS IN VICINITY OF A SURFACE TROUGH/LOW LEVEL
UPSLOPE...WITH ADDITIONAL DEVELOPMENT BY LATE AFTERNOON
SOUTHEASTWARD ALONG A SURFACE LOW/DRYLINE ACROSS THE SOUTH CENTRAL
PLAINS. WHILE A FEW TORNADOES WILL BE POSSIBLE ACROSS A BROAD
PORTION OF THE CENTRAL PLAINS/NORTH-CENTRAL HIGH PLAINS...A SOMEWHAT
MORE PROBABLE LOCATION MAY EXIST ACROSS CENTRAL KS IN VICINITY OF A
SURFACE TRIPLE POINT...WITH A DEEPENING SURFACE LOW ACROSS THE OK/TX
PANHANDLES AND SOUTHWEST KS...AND A REMNANT BOUNDARY ACROSS
KS/POSSIBLE CONVECTIVE OUTFLOW. PORTIONS OF KS AND SURROUNDING AREAS
MAY ULTIMATELY WARRANT AN UPGRADE TO A CATEGORICAL MODERATE RISK.
...CAROLINAS...
BENEATH MODEST/DIFFLUENT WEST-NORTHWESTERLY FLOW ALOFT...AMPLE
HEATING COINCIDENT WITH MAINLY 60S F SURFACE DEWPOINTS WILL RESULT
IN A MODERATELY UNSTABLE AIRMASS ACROSS PORTIONS OF THE CAROLINAS
THIS AFTERNOON. TSTMS MAY INITIALLY DEVELOP ALONG THE HIGHER TERRAIN
AND/OR THE SEA BREEZE...WITH SUBSEQUENT SOUTHEASTWARD PROPAGATING
MULTICELLULAR CLUSTERS CAPABLE OF DAMAGING WINDS/SOME HAIL.
ADDITIONALLY...PENDING UPSTREAM DEVELOPMENT ACROSS THE TN
VALLEY...ONE OR MORE CLUSTERS OF TSTMS MAY APPROACH PORTIONS OF THE
SOUTHERN APPALACHIANS/CAROLINAS DURING THE EVENING...WITH A
CONTINUED WIND/HAIL THREAT POSSIBLE.
...NY/EASTERN PA INTO WESTERN NEW ENGLAND...
WEAKENING/BROAD UPPER LOW WILL MIGRATE EASTWARD OVER NY/NEW ENGLAND
TODAY. DIURNAL HEATING BENEATH COOL MID LEVEL TEMPERATURES /-20C AT
500 MB/ WILL RESULT IN STEEPENING LOW/MID LEVEL LAPSE RATES THROUGH
THE AFTERNOON...WITH AN UPSWING IN SCATTERED TSTM DEVELOPMENT LIKELY
ACROSS PORTIONS OF NY/EASTERN PA INTO WESTERN NEW ENGLAND. EVEN WITH
WEAK LOW TO MID TROPOSPHERIC FLOW AND LIMITED CONVERGENCE...IT
APPEARS THE STEEP LAPSE RATE ENVIRONMENT/MODEST BUOYANCY WILL
SUPPORT THE POSSIBILITY OF TSTMS CAPABLE OF ISOLATED SEVERE
HAIL/STRONG WIND GUSTS. ANY SUCH THREAT WOULD LIKELY WANE BY AROUND
SUNSET.
..GUYER/GRAMS.. 06/15/2009
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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