SPC AC 030554
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1254 AM CDT FRI JUL 03 2009
   
   VALID 031200Z - 041200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FOR THE CNTRL PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FOR CNTRL MT...
   
   ...SYNOPSIS...
   UPPER-LEVEL TROUGH OVER THE ERN GREAT LAKES/NORTHEAST WILL GRADUALLY
   SHIFT EWD INTO NEW ENGLAND AS AN UPSTREAM SPEED MAX OVER SWRN
   ONTARIO DIVES SEWD ACROSS THE GREAT LAKES. UPPER-LEVEL RIDGE AXIS
   CENTERED OVER THE CNTRL/SRN HIGH PLAINS WILL FLATTEN AS AN IMPULSE
   IN THE ERN GREAT BASIN EJECTS EWD INTO THE MID-MO RIVER VALLEY BY
   FRI EVENING. NUMEROUS SMALLER-SCALE DISTURBANCES WITHIN BROADER WLY
   FLOW REGIME WILL PERSIST ACROSS THE NRN/CNTRL GREAT BASIN/ROCKIES.
   
   ...CNTRL PLAINS...
   LARGE-SCALE ASCENT WILL INCREASE FRI DOWNSTREAM OF AN EMBEDDED
   MID/UPPER-LEVEL SPEED MAX SUBJECTIVELY ANALYZED OVER THE ERN GREAT
   BASIN THU EVENING. LATEST MODEL FORECASTS ARE REASONABLY CONSISTENT
   WITH DEEPENING A LEE CYCLONE INTO WRN KS...AND THE NWD RETURN OF A
   WARM FRONT ARCING INTO SRN NEB TO NWRN KS BY 04/00Z. SUBSTANTIAL
   AMPLIFICATION OF KINEMATIC FLOW WILL PROMOTE STRENGTHENING LOW-LEVEL
   WAA ATOP THE FRONTAL SURFACE. ELEVATED TSTMS SHOULD BE ONGOING AT
   03/12Z ACROSS NRN NEB AND DEVELOP EWD INTO THE MID-MO RIVER VALLEY
   DURING THE AFTERNOON...POSING A THREAT FOR MARGINAL SEVERE
   HAIL/WIND. SOMEWHAT MORE ROBUST SEVERE POTENTIAL SHOULD EVOLVE
   FARTHER SWWD AT PEAK HEATING ALONG THE WARM FRONT AS CONVERGENCE AND
   AFOREMENTIONED LARGE-SCALE ASCENT AID IN BREAKING CAPPING INVERSION.
   
   MODEL FORECASTS DIFFER SIGNIFICANTLY WITH THE DEGREE OF BOUNDARY
   LAYER MOISTENING...WITH THE 02/21Z NAMKF APPEARING OVERDONE WITH
   LOWER TO MIDDLE 70S SURFACE DEW POINTS AND MEAN MIXING RATIOS AROUND
   15 G/KG INTO SERN NEB/NERN KS BY 04/00Z. ALTHOUGH EVAPOTRANSPIRATION
   SHOULD LOCALLY ENRICH MOISTURE...03/00Z RAOBS SUGGEST MEAN MIXING
   RATIOS AOA 15 G/KG WERE RESTRICTED TO THE TX GULF COAST. MIDDLE 60S
   SURFACE DEW POINTS APPEAR TO BE MORE PROBABLE AND SHOULD RESULT IN
   RELATIVELY HIGH-BASED SUPERCELL TSTMS CONDUCIVE TO SEVERE
   HAIL/WINDS. OVERALL THREAT WILL LIKELY BE TEMPERED BY RELATIVELY
   MODEST HIGH-LEVEL LAPSE RATES...DESPITE STRONG DEEP-LAYER SHEAR.
   WITH LOW-LEVEL HODOGRAPHS EXPECTED TO BECOME QUITE LARGE ALONG THE
   FRONTAL BOUNDARY DURING THE EVENING AS THE LLJ INCREASES AOA 40
   KT...A TORNADO OR TWO MAY OCCUR NEAR SUNSET. UPSCALE GROWTH INTO ONE
   OR MORE MCS/S SHOULD OCCUR BY LATE FRI EVENING AND PERSIST INTO THE
   OVERNIGHT HOURS. HOWEVER...SEVERE POTENTIAL SHOULD WANE WITH LIMITED
   ELEVATED INSTABILITY.
   
   ...LEE OF THE NRN ROCKIES...
   IN RESPONSE TO THE EJECTING IMPULSE ACROSS THE CNTRL
   PLAINS...LOW-LEVEL E/SELYS SHOULD PRIMARILY BECOME N/NWLYS ACROSS
   THE WY/NEB PANHANDLE REGION. FARTHER N...RELATIVELY ANEMIC UPSLOPE
   FLOW MAY REMAIN ACROSS MT. HERE TOO...MID/UPPER-LEVEL LAPSE RATES
   WILL BE STEEPER COMPARED TO AREAS FARTHER SEWD. WITH MLCAPES OF 1000
   TO 2000 J/KG EXPECTED AT PEAK HEATING AND 500 MB WLYS OF 25-30
   KT...SCATTERED TSTMS DEVELOPING OVER THE HIGHER TERRAIN WILL POSE A
   THREAT FOR SEVERE HAIL/WIND AS THEY PROPAGATE ONTO THE ADJACENT
   PLAINS.
   
   ...NRN FL...
   ISOLATED TO SCATTERED TSTMS SHOULD DEVELOP FRI AFTERNOON ALONG
   FRONTAL BOUNDARY STALLING OVER NRN FL. THE REGION WILL LIE ON THE
   SRN PERIPHERY OF MODERATE MID/UPPER-LEVEL WLYS. WITH MLCAPE OF 2000
   TO 2500 J/KG DEVELOPING S OF THE FRONT...A FEW LOOSELY
   ORGANIZED/MULTICELL TSTMS MAY PRODUCE DAMAGING WINDS/SEVERE HAIL.
   
   ...SRN NEW ENGLAND...
   SHORT WAVE TROUGH OVER THE ERN GREAT LAKES WILL PROGRESS EWD INTO
   SRN NEW ENGLAND BY EARLY FRI AFTERNOON...AND ASCENT ASSOCIATED WITH
   THE SHORT WAVE SHOULD RESULT IN ISOLATED TO SCATTERED TSTMS. BELT OF
   STRONGER MID-LEVEL W/SWLYS AHEAD OF THE SHORT WAVE SHOULD GRADUALLY
   SHIFT OFFSHORE THROUGH THE DAY. SETUP SHOULD YIELD A RELATIVELY
   SHORT-DURATION WINDOW FOR MARGINAL SEVERE HAIL/WIND DURING THE EARLY
   AFTERNOON.
   
   ...GREAT BASIN...
   SEVERAL SMALL-SCALE IMPULSES WILL HELP MAINTAIN A BELT OF MODERATE
   MID-LEVEL WLYS. IN CONJUCTION WITH INVERTED-V THERMODYNAMIC PROFILES
   AT LOWER ELEVATIONS...A FEW MICROBURSTS/HAIL EVENTS APPEAR POSSIBLE.
   
   ..GRAMS/HURLBUT/RACY.. 07/03/2009
   
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