SPC AC 070547
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1247 AM CDT SUN JUN 07 2009
VALID 071200Z - 081200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF ERN KS...SERN
NEB...SWRN IA AND NWRN MO...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
NRN OK TO SRN WI...
...CENTRAL PLAINS/MID MS VALLEY...
EARLY MORNING WV IMAGERY DEPICTS A WELL DEFINED UPPER VORT AND
ASSOCIATED SHORTWAVE TROUGH BEGINNING TO EJECT NEWD ACROSS THE LOWER
CO RIVER VALLEY OF SRN NV/CA. BOTH THE NAM AND GFS SUGGEST MID
LEVEL SPEED MAX ASSOCIATED WITH THIS FEATURE WILL EJECT ACROSS NRN
NM BEFORE SHIFTING INTO KS BY LATE AFTERNOON...ENHANCING SEVERE
POTENTIAL WITH THUNDERSTORM ACTIVITY THAT SHOULD DEVELOP ALONG/AHEAD
OF FRONTAL ZONE. PRIOR TO THIS DEVELOPMENT...AN EARLY MORNING MCS
WILL BE ONGOING ACROSS THE MID MS VALLEY IN ASSOCIATION WITH STRONG
LOW LEVEL WARM ADVECTION. THIS THUNDERSTORM COMPLEX WILL LIKELY
ENHANCE ELY LOW LEVEL COMPONENT ACROSS IA AS CONVECTIVE OUTFLOW
BECOMES DRAPED ALONG THE IA/MO BORDER INTO SRN NEB WHERE IT SHOULD
INTERSECT SURGING COLD FRONT. NAM IS A BIT FARTHER SE WITH COLD
FRONTAL POSITION OVER KS AT 00Z THAN GFS AND THIS SEEMS MORE
REASONABLE GIVEN THE AIRMASS OVER THE NRN PLAINS ATTM.
LATEST THINKING IS AFTER THE EARLY MORNING MCS OVER THE MID MS
VALLEY...MUCH OF THE DAY WILL PROVE CONVECTIVE-FREE OVER THE CNTRL
PLAINS AS SFC PARCELS WILL BE CAPPED PRIOR TO MID-LATE AFTERNOON.
VERY STRONG HEATING WILL OCCUR ACROSS THE SRN HIGH PLAINS INTO
SCNTRL KS AHEAD OF COLD FRONT WITH TEMPERATURES EXPECTED TO RISE
WELL INTO THE MID 90S. CONVECTION WILL LIKELY INITIATE ALONG NERN
PLUME OF STEEP LAPSE RATES WHERE PARCEL RESIDENCE TIME WILL BE
MAXIMIZED ALONG ZONE OF STRONG CONVERGENCE. AT THIS TIME IT APPEARS
THUNDERSTORMS WILL DEVELOP ACROSS SCNTRL KS IMMEDIATELY AHEAD OF SFC
LOW THEN TRACK/DEVELOP NEWD INTO INCREASINGLY MOIST/UNSTABLE AIRMASS
CHARACTERIZED BY MLCAPE VALUES AOA 3000 J/KG. GIVEN THE APPROACHING
SHORTWAVE TROUGH...UPDRAFTS SHOULD ORGANIZE QUICKLY WITH SUPERCELLS
THE PRIMARY CONVECTIVE MODE. VERY LARGE HAIL SHOULD ACCOMPANY MANY
OF THESE STORMS GIVEN THE STEEP LAPSE RATES AND HIGH CAPE.
ADDITIONALLY...LOW LEVEL SHEAR WILL BE MAXIMIZED OVER NERN KS INTO
SERN NEB/NWRN MO ALONG DECAYING OUTFLOW WHERE FORECAST SOUNDINGS
SUGGEST SFC-3KM HELICITY WILL BE ON THE ORDER OF 300 M2/S2 OVER THIS
REGION. FORECAST SOUNDINGS SUGGEST A FEW TORNADOES ARE POSSIBLE
ACROSS THE MDT RISK REGION...ESPECIALLY AS LLJ INCREASES INTO THE
EARLY EVENING HOURS. SEVERE THREAT WILL SPREAD ACROSS ERN KS/NEB
INTO IA/NRN MO DURING THE LATE EVENING...IMMEDIATELY AHEAD OF SFC
LOW. ONE OR MORE MCS-TYPE COMPLEXES SHOULD EVOLVE ACROSS THE MID MS
VALLEY DURING THE OVERNIGHT HOURS. LARGE HAIL AND DAMAGING WINDS
WILL BECOME THE PRIMARY SEVERE THREATS AS MCS MATURES.
...ELSEWHERE...
ISOLATED-SCATTERED THUNDERSTORMS WILL ONCE AGAIN DEVELOP ALONG
DRYLINE ACROSS WEST TX AS TEMPERATURES RISE INTO THE UPPER 90S TO
NEAR 100F. HIGH BASED CONVECTION MAY PRODUCE A FEW SEVERE WIND
GUSTS OR LARGE HAIL.
A FEW STRONG STORMS MAY ALSO DEVELOP ALONG THE EAST COAST OF SOUTH
FL. FORECAST SOUNDINGS SUGGEST SUFFICIENT CAPE FOR ROBUST UPDRAFTS
WITHIN MARGINAL SHEARED ENVIRONMENT. ISOLATED LARGE HAIL OR MICRO
BURSTS ARE THE THREATS WITH THIS DIURNAL ACTIVITY.
..DARROW/JEWELL.. 06/07/2009
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