SPC AC 141246
DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0746 AM CDT FRI MAR 14 2008
VALID 141300Z - 151200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF SRN KS/ERN OK
ACROSS THE MS/TN VALLEYS...
CORRECTED TO ADD INFORMATION ON SHV SOUNDING
...SYNOPSIS...
BELT OF FAST ZONAL FLOW WILL CONTINUE FROM THE WEST COAST...ACROSS
THE MS VALLEY...TO THE SOUTHEAST THROUGH TODAY. LOW-AMPLITUDE SHORT
WAVE TROUGHS EMBEDDED WITHIN THIS FAST FLOW REGIME WILL INDUCE AREAS
OF STRONGER DEEP-LAYER ASCENT THAT WILL EITHER SUSTAIN ONGOING DEEP
CONVECTION...OR LEAD TO NEW CONVECTIVE DEVELOPMENT DURING THE
PERIOD.
...TN VALLEY...
LEADING DISTURBANCE WAS CROSSING THE LOWER MS VALLEY THIS MORNING
WITH A TRAILING SRN BRANCH COMPONENT TRACKING OVER THE NRN GULF.
LIFT WITH THE MS VALLEY FEATURE SHOULD MAINTAIN A WEAK FRONTAL WAVE
CYCLONE THAT WILL DEVELOP ACROSS KY/TN TODAY...AND THEN TO THE MID
ATLANTIC COAST BY SATURDAY MORNING.
SURFACE-BASED INSTABILITY WITHIN AND AHEAD OF THE REGION OF STRONGER
ASCENT ASSOCIATED WITH THE LOW-AMPLITUDE UPPER WAVE AND SURFACE
REFLECTION IS LIKELY TO REMAIN MARGINAL OVER MUCH OF THE REGION DUE
TO CLOUD COVER/PRECIPITATION. AN EXCEPTION MAY OCCUR OVER PARTS OF
MS/AL DURING THE DAY IF AIR MASS CAN DESTABILIZE IN THE WAKE OF
MORNING ACTIVITY AND PRIOR TO COMPLETE PASSAGE OF STRONGER LIFT
ASSOCIATED WITH THE SHORTWAVE TROUGH. PLUME OF STEEP 700-500MB LEVEL
LAPSE RATES /7.1 C/KM PER SHV SOUNDING...AND POTENT VERTICAL SHEAR
ACROSS THIS AREA WILL SUSTAIN THE RISK OF A FEW SEVERE STORMS WITH
HAIL BEING THE PRIMARY HAZARD. ANOTHER ROUND OF LOCALLY STRONG
STORMS MAY DEVELOP ACROSS THE PARTS OF THIS AREA THROUGH EARLY
SATURDAY AS THE NEXT LOW-AMPLITUDE DISTURBANCE SPREADS QUICKLY EAST
FROM THE SRN PLAINS IN FAST ZONAL FLOW REGIME.
...FL...
THE TRAILING SEGMENT OF THE MS VALLEY SHORTWAVE TROUGH...CLEARLY
EVIDENT IN MORNING WV IMAGERY ACROSS THE NRN GULF...WILL CONTINUE TO
SPREAD EAST THIS MORNING...TO NRN FL THROUGH LATE TODAY.
LIFT/DESTABILIZATION WITH THIS FEATURE WAS DRIVING AN MCS OVER THE
NERN GULF THIS MORNING PER COASTAL RADARS...IR IMAGERY...AND
LIGHTNING DETECTION DATA. DOWNSTREAM AIR MASS ACROSS FL WAS DRY AND
STABLE IN WAKE OF MOST RECENT INTRUSION OF CONTINENTAL POLAR AIR AND
THIS WILL LIMIT THE DEVELOPMENT OF STRONGER INSTABILITY ACROSS LAND
AREAS TODAY. HOWEVER...TSTM CHANCES WILL INCREASE ACROSS THE
PENINSULA ASSOCIATED WITH STRENGTHENING ISENTROPIC LIFT AND MOISTURE
TRANSPORT ACCOMPANYING THE SRN BRANCH DISTURBANCE. IT IS POSSIBLE
THAT A FEW STORMS COULD ATTAIN SEVERE LEVELS...WITH WIND/ISOLATED
HAIL POTENTIAL GREATEST ALONG THE GULF COAST. SEVERE WEATHER
POTENTIAL COULD EXTEND INLAND IF DIFFERENTIAL HEATING BOUNDARY AND
GREATER DESTABILIZATION CAN OCCUR. LATEST GUIDANCE CONTINUES TO
INDICATE THAT THIS POTENTIAL REMAINS LOW AND AREAL COVERAGE OF ANY
SEVERE THREAT WILL PROBABLY REMAIN LIMITED. THUS...LOW SEVERE
PROBABILITIES WILL BE MAINTAINED AT THIS TIME.
...SRN PLAINS/OZARKS TO MS VALLEY TONIGHT/OVERNIGHT...
THE NEXT SHORT WAVE TROUGH WILL TAKE FORM OUT OF THE FAST MID/UPPER
LEVEL FLOW CROSSING THE FOUR CORNERS REGION AND GAIN SOME AMPLITUDE
OVER THE SRN PLAINS THROUGH TONIGHT. CONCENTRATED REGION OF MODEST
HEIGHT FALLS WITH THIS SYSTEM WILL CONTRIBUTE TO CYCLOGENESIS OVER
THE TX PANHANDLE LATER TODAY. SIMILAR TO THURSDAY NIGHT...LIFT AND
STEEP LAPSE RATES WITH THIS SYSTEM WILL COINCIDE WITH LOW LEVEL
MOIST AXIS...AND RESIDUAL DIURNAL HEATING...TO BRING AN INCREASING
CHANCE OF STRONG TO SEVERE TSTM DEVELOPMENT ACROSS PORTIONS OF
KS/MO/OK/AR THROUGH THIS EVENING AND OVERNIGHT.
AIR PARCEL TRAJECTORIES ARE FORECAST TO REACH A RELATIVELY HIGH LFC
AROUND 700MB AND CONTRIBUTE TO RAPID CONVECTIVE INITIATION ALONG AND
NORTH OF THE SURFACE LOW TRACK AND DEVELOPING WARM FRONT...FROM NWRN
OK/CNTRL KS TO NERN OK AND SWRN MO THROUGH LATE EVENING. WARM AND
MARGINALLY MOIST BOUNDARY LAYER ACROSS THESE AREAS WILL RESULT IN
MLCAPE AOB 1000 J/KG. THIS INSTABILITY SHOULD PROVE MORE THAN
ADEQUATE FOR SEVERE STORM FORMATION GIVEN MAGNITUDE OF LAPSE RATES
AND POTENT SHEAR EXPECTED. PRONOUNCED TURNING/HELICITY IN THE NEAR
SURFACE UPDRAFT LAYER IS DEPICTED IN FORECAST WIND PROFILES FROM
KS/OK BORDER EWD TO OZARKS. GIVEN RELATIVELY DRY BOUNDARY
LAYER...INITIAL STORMS MAY ACQUIRE LP-SUPERCELL CHARACTERISTICS WITH
ATTENDANT THREATS OF LARGE HAIL AND STRONG OUTFLOW WINDS.
CONVECTION SHOULD CONSOLIDATE INTO AN MCS OR TWO THROUGH LATE
TONIGHT AS THE DEEPENING CYCLONE TRACKS EAST ALONG THE INTENSIFYING
WARM FRONT FROM KS/OK TO THE OZARKS. DAMAGING WIND AND SEVERE HAIL
THREAT MAY INCREASE THROUGH THE NIGHT AS CONVECTION TAPS LOW LEVEL
MOIST AXIS FROM THE ARKLATEX TO THE MS VALLEY. DEEP-LAYER WLY FLOW
OF 40-60KT NOSING INTO AND BECOMING COINCIDENT WITH THE MCS WILL
FURTHER SUPPORT FAST MOVING STORMS...OR A COMPLEX OF STORMS...WITH
AN ENHANCED POTENTIAL FOR DAMAGING WINDS DEVELOPING AS FAR EAST AS
WRN TN/MS THROUGH DAYBREAK SATURDAY.
..SELECT A FORECASTER.. 03/14/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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