SPC AC 071245
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0745 AM CDT MON APR 07 2008
VALID 071300Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SRN AND CNTRL
PLNS...
...SYNOPSIS...
BROAD...LOW AMPLITUDE TROUGH WILL PERSIST OVER THE WRN AND N CNTRL
U.S. THIS PERIOD WHILE HEIGHTS SLIGHTLY REBOUND ALONG THE E CST.
OVERALL PATTERN WILL MAINTAIN SLIGHTLY DIFFLUENT CYCLONIC FLOW OVER
THE PLNS...WITH THE MAIN BELT OF FLOW EXTENDING FROM THE SRN GRT
BASIN ACROSS THE CNTRL PLNS AND MID MS VLY TO LWR MI. WITHIN THIS
JET...SIGNIFICANT SHORTWAVE IMPULSES ATTM ARE OVER ERN NV AND SE MN.
THE NV SYSTEM SHOULD CONTINUE E INTO TO THE CNTRL HI PLNS BY 12Z
TUESDAY...WHILE THE MN SYSTEM EJECTS AS AN OPEN WAVE ACROSS LK
HURON.
AT THE SFC...TRAILING COLD FRONT ASSOCIATED WITH MN UPR SYSTEM HAS
BECOME STATIONARY OVER N TX JUST S OF THE RED RVR. THE FRONT SHOULD
RETURN N ACROSS OK TODAY/EARLY TONIGHT AS LEE CYCLONE STRENGTHENS
OVER SE CO IN RESPONSE TO APPROACHING UPR DISTURBANCE. THE NRN PART
OF THE SAME COLD FRONT...MEANWHILE...SHOULD ACCELERATE E/NE ACROSS
THE UPR MS VLY/UPR GRT LKS.
...SRN/CNTRL PLNS...
SATELLITE AND SFC DATA SHOW SUBSTANTIAL BOUNDARY LAYER MOISTURE
SPREADING N ACROSS CNTRL AND E TX ATTM...IN RESPONSE TO
STRENGTHENING SLY LLJ OVER THE SRN PLNS. SFC DEWPOINTS IN THE UPR
50S SHOULD EXTEND N TO ABOUT I-40 IN CNTRL OK BY LATE AFTN...WITH
VALUES RISING INTO THE LOW 60S ACROSS MUCH OF CNTRL AND ERN OK BY
EARLY TUESDAY AS WARM FRONT LIFTS N TO NEAR THE KS/OK BORDER NEAR
BVO.
SFC HEATING AND APPROACH OF NV IMPULSE SHOULD FAVOR SE-DEVELOPMENT
OF CO LEE CYCLONE INTO THE WRN OK/NW TX PANHANDLE BY LATE IN THE
DAY. THIS SHOULD MAINTAIN A SLIGHTLY-BACKED/CONVERGENT LOW-LEVEL
FLOW INVOF WARM FRONT FROM THE RED RVR INTO SRN/WRN OK. AND...
CURRENT VWP DATA ARE INCONCLUSIVE. BUT SATELLITE AND MODEL FCSTS
SUGGEST PRESENCE OF A LOW AMPLITUDE DISTURBANCE NOW OVER THE FOUR
CORNERS REGION THAT EXTRAPOLATES TO THE SRN/CNTRL HI PLNS THIS AFTN.
EVEN IN THE ABSENCE OF AN IDENTIFIABLE SHORTWAVE IMPULSE...
COMBINATION OF STRONG SFC HEATING...CONVERGENT/INCREASINGLY MOIST
LOW-LEVEL FLOW...STEEP LOW- TO MID-LEVEL LAPSE RATES AND MODERATELY
STRONG/DIFFLUENT UPR FLOW WILL YIELD A SETUP FAVORABLE FOR ISOLATED
SUPERCELLS ALONG AND JUST N OF WARM FRONT. WITH SBCAPE INCREASING
TO AOA 1500 J/KG...A STORM OR TWO COULD ALSO FORM NEAR THE DRY LINE
EXTENDING S INTO NW TX.
WIND PROFILES WILL FEATURE 20-25 KT SSELY NEAR-SFC FLOW
VEERING/INCREASING TO NEAR 50 KT WSWLY AT 500 MB. THIS SHOULD
FOSTER SUSTAINED STORM ROTATION...WITH A HIGH LIKELIHOOD FOR VERY
LARGE HAIL/HIGH WIND AND POSSIBLY TORNADOES AS THE STORMS
MOVE/SPREAD SLOWLY E INTO CNTRL OK AND FAR N CNTRL TX BY EARLY
EVENING.
LACK OF RICHER BOUNDARY-LAYER MOISTURE SHOULD SOMEWHAT LIMIT THE
OVERALL TORNADO POTENTIAL. BUT ENVIRONMENT SHOULD FOSTER LOW-LEVEL
STORM ROTATION...ESPECIALLY NEAR WARM FRONT. AND...IF DISCRETE
STRUCTURES ARE MAINTAINED...SUCH A THREAT MAY CONTINUE INTO TONIGHT
OVER WRN...CNTRL AND EVENTUALLY ERN OK AS LLJ FURTHER STRENGTHENS IN
RESPONSE TO DIURNAL DECOUPLING AND THE CONTINUED EWD MOTION OF NV
TROUGH.
LATER TONIGHT/EARLY TUESDAY...STRENGTHENING WAA SHOULD RESULT IN AN
EXPANSION OF STORM COVERAGE NEAR AND N OF THE WARM FRONT INTO PARTS
OF SRN/ERN KS AND WRN MO. POTENTIAL WILL CONTINUE FOR ISOLATED
TORNADOES... BOTH NEAR FRONT AND IN WARM SECTOR IN OK...WITH HAIL
THREAT EXPANDING NWD INTO KS/MO.
A NARROW CORRIDOR OF OK...PERHAPS FROM W CNTRL ENE INTO THE NE PART
OF THE STATE...MAY REQUIRE UPGRADE TO MODERATE RISK IN LATER
OUTLOOKS AS THE EVENING/OVERNIGHT POSITION OF THE WARM FRONT...AND
THE PART OF THE STATE MOST LIKELY TO RECEIVE MORE CONCENTRATED/
POSSIBLE REPEAT SUPERCELL ACTIVITY...BECOMES MORE APPARENT.
...NE MI/LK HURON...
POTENT NRN STREAM UPR LOW/TROUGH WILL ASSUME A NEGATIVE TILT AS IT
EJECTS NE ACROSS THE UPR GRT LKS LATER TODAY/TONIGHT. ASSOCIATED
BAND OF STRONG FORCING FOR ASCENT AND COLD FRONT WILL MOVE QUICKLY
NE ACROSS NE MI FOLLOWING MAX HEATING TIME THIS AFTN. CONVERGENCE
ALONG FRONT MAY SUPPORT A LINE OF LOW-TOPPED CONVECTION/POSSIBLE
TSTMS. GIVEN RELATIVELY LARGE T-TD SPREADS...30-40 KT MEAN LOWER
TROPOSPHERIC FLOW AND 500 MB TEMPS AOA MINUS 22C...SETUP COULD YIELD
A SPOT OR TWO OF HAIL AND/OR STRONG SFC WINDS TIL SUNSET.
...S FL...
LOWER TROPOSPHERIC WINDS HAVE VEERED TO NORTH OF WEST ACROSS S FL
THIS MORNING IN RESPONSE TO DEVELOPING SFC WAVE AND ASSOCIATED UPR
DISTURBANCE OFF THE FL E CST. THE LOW LEVEL FLOW SHOULD REMAIN
LARGELY DIVERGENT AND LIGHT NLY THROUGH THE DAY OVER S FL AS THE
WAVE CONTINUES SLOWLY ENEWD. COUPLED WITH WEAK SHEAR...THE
PROSPECTS FOR SUSTAINED TSTMS...OR ORGANIZED SVR STORMS...LOOK
MINIMAL.
..CORFIDI/JEWELL.. 04/07/2008
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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