
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT MON SEP 01 2014
VALID 011630Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF NORTHERN
OKLAHOMA AND SOUTHERN KANSAS TO THE MID-MISSISSIPPI VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF MICHIGAN...
...SUMMARY...
ISOLATED TO SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED FROM
PORTIONS OF NORTHERN OKLAHOMA AND SOUTHERN KANSAS TO THE
MID-MISSISSIPPI VALLEY LATER TODAY INTO TONIGHT...AND ACROSS
PORTIONS OF MICHIGAN THIS AFTERNOON.
...SYNOPSIS...
WATER VAPOR LOOPS INDICATE BROADLY CYCLONIC FLOW EXTENDING FROM
CANADA INTO THE N-CNTRL CONUS...WITH ONE EMBEDDED SHORTWAVE TROUGH
LIFTING NEWD ACROSS PARTS OF THE WRN GREAT LAKES...AND AN UPSTREAM
SPEED MAX EMERGING OVER THE CNTRL HIGH PLAINS. THESE FEATURES WILL
CONTINUE TO ADVANCE THROUGH THE BROADER CYCLONIC FLOW...SERVING TO
MAINTAIN A BELT OF MODERATE TO STRONG MID-LEVEL WLYS/SWLYS FROM THE
CNTRL PLAINS TO THE GREAT LAKES. AN EXTENSIVE SFC FRONT LIES FROM
WRN LAKE SUPERIOR SWWD TO THE TX PANHANDLE. THIS BOUNDARY WILL
ADVANCE EWD ACROSS PARTS OF THE MIDWEST AND GREAT LAKES...WHILE
TRAILING SWWD INTO THE SRN PLAINS AS A STATIONARY FRONT.
...PORTIONS OF THE SOUTHERN PLAINS NORTHEASTWARD TO THE GREAT LAKES
REGION THIS AFTERNOON INTO TONIGHT...
EXTENSIVE CONVECTIVE DEBRIS COVERS THE WARM/MOIST SIDE OF THE
BOUNDARY AT PRESENT. REGARDLESS...SFC DEWPOINTS IN THE UPPER
60S/LOWER 70S EXTEND POLEWARD TO AN OUTFLOW BOUNDARY/PRE-FRONTAL
TROUGH ANALYZED FROM NRN OK TO THE MID-MS VALLEY TO LAKE MI. THIS
WILL SUPPORT CORRIDORS OF AT LEAST MODEST CONDITIONAL INSTABILITY TO
ENHANCE THE POTENTIAL FOR LATER GENERATIONS OF CONVECTIVE
DEVELOPMENT.
THE SEGMENT OF THE OUTFLOW BOUNDARY/PRE-FRONTAL TROUGH FROM THE SRN
PLAINS TO THE OZARKS TROUGH LIES BENEATH AN EML PLUME SAMPLED BY THE
12Z OUN SOUNDING...WHICH FEATURES A PROMINENT WARM LAYER BENEATH
H7-H5 LAPSE RATES AROUND 8.3 C/KM. AS POCKETS OF INSOLATION
MATERIALIZE IN THE WAKE OF ONGOING CLOUDS/PRECIPITATION...MLCAPE
VALUES WILL LIKELY INCREASE TO 2000-3000 J/KG GIVEN THE AMPLE
BOUNDARY MOISTURE DEWPOINTS AND STEEP MID-LEVEL LAPSE RATES. DESPITE
QUASI-NEUTRAL MID-LEVEL HEIGHT TENDENCIES...CONVERGENCE ALONG THE
AFOREMENTIONED SFC BOUNDARIES SHOULD BE SUFFICIENT FOR ISOLATED TO
SCATTERED THUNDERSTORM DEVELOPMENT BY LATE AFTERNOON FROM NERN OK
AND SERN KS INTO SRN MO...WITH ACTIVITY INCREASING IN COVERAGE INTO
THE EVENING HOURS WITH A NOCTURNALLY INCREASING LLJ. THE PRESENCE OF
AROUND 30-40 KT OF EFFECTIVE BULK SHEAR WILL BE SUFFICIENT FOR
INITIALLY ROTATING STORMS...WITH ACTIVITY LIKELY CONGEALING INTO
CONVECTIVE CLUSTERS THAT WILL SPREAD EWD/ESEWD INTO THE OVERNIGHT
HOURS. DMGG WIND GUSTS...LARGE HAIL -- SOME POSSIBLY SIGNIFICANT
DURING INCIPIENT SUPERCELL PHASES -- AND A TORNADO OR TWO WILL BE
POSSIBLE.
MEANWHILE...STRONGER DEEP-LAYER ASCENT RELATED TO THE AFOREMENTIONED
SHORTWAVE TROUGH WILL REMAIN CONFINED TO PORTIONS OF MI DURING THE
NEXT SEVERAL HOURS. DCVA PRECEDING THE TROUGH IS EMERGING OVER AREAS
OF A DIURNALLY HEATED...MOIST BOUNDARY LAYER TO SUPPORT RECENT
THUNDERSTORM DEVELOPMENT OVER WRN LOWER MI. STRONG MID-LEVEL FLOW
ATTENDANT TO THE TROUGH WILL HAVE THE POTENTIAL TO SUPPORT ORGANIZED
MULTICELL CLUSTERS AND PERHAPS A SUPERCELL OR TWO WITH DMGG WIND
GUSTS AND POSSIBLY A TORNADO.
ELSEWHERE...THE AFOREMENTIONED SHORTWAVE TROUGH WILL BECOME
INCREASINGLY REMOVED FROM THE PRE-FRONTAL REGIME BETWEEN THE TWO
SLIGHT-RISK AREAS...WHERE WIDESPREAD CLOUDS ARE STUNTING
DESTABILIZATION AMIDST POOR MID-LEVEL LAPSE RATES. THESE FACTORS
WILL MARGINALIZE THE SVR-TSTM POTENTIAL IN THESE AREAS.
...EASTERN WYOMING / NORTHERN NEBRASKA / SOUTHERN SOUTH DAKOTA...
ASCENT IN THE EXIT REGION OF THE AFOREMENTIONED MID-LEVEL SPEED MAX
WILL ENCOURAGE TSTM DEVELOPMENT THIS AFTERNOON AS STEEP
LOW/MID-LEVEL LAPSE RATES BECOME ESTABLISHED. MID-LEVEL FLOW WILL BE
SUFFICIENTLY STRONG FOR A FEW MULTICELL CLUSTERS WITH SPORADIC SVR
WIND GUSTS POSSIBLE. HOWEVER...THE LACK OF MORE ROBUST
BOUNDARY-LAYER MOISTURE/BUOYANCY SHOULD PREVENT A MORE SUBSTANTIAL
SVR RISK FROM EVOLVING.
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