16Z CONVECTIVE OUTLOOK
SPC
STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK
DAY 1 CONVECTIVE OUTLOOK
VALID
THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF SE SD/CNTRL AND ERN
NEB/WRN AND CNTRL KS/WRN AND CNTRL OK/WRN AND N TX....
SIGNIFICANT SEVERE WEATHER POSSIBLE OVER PARTS OF CNTRL AND SRN
PLNS THIS AFTERNOON THROUGH TONIGHT...
...SYNOPSIS...
ZONAL SPLIT FLOW PATTERN WILL CONTINUE ACROSS THE LOWER 48. SRN
STREAM....WHICH ATTM EXTENDS FROM AZ/NM INTO THE TN VLY...EXPECTED
TO SHOW LITTLE OVERALL CHANGE THIS PERIOD...EXCEPT FOR A
CONTINUATION OF SLIGHT RIDGING NOW APPARENT IN WV IMAGERY OVER THE
SRN HI PLNS. STRONGER NRN STREAM JET WILL CONTINUE FROM WA/NRN ID
MT INTO S CNTRL CANADA. SRN EXTENSION OF A WEAK IMPULSE IN THE NRN
STREAM APPEARS TO BE OVER CNTRL NEB/ERN CO ATTM AND SHOULD CONTINUE
ENEWD THROUGH THE DAY.
AT LOWER LEVELS...LITTLE OVERALL CHANGE EXPECTED. COMPLEX PATTERN
WITH SEGMENTED LEE TROUGH/DRYLINE WILL PERSIST FROM CNTRL SD/NEB
SSWWD INTO W TX/SE NM. LOW NOW OVER SE CO/SW KS APPEARS TO BE
MAINLY THERMALLY-DRIVEN WILL PROBABLY DEEPEN A LITTLE WITH SURFACE
HEATING THIS AFTERNOON. THIS SHOULD RESULT IN SLIGHT BACKING OF
THE LOW LEVEL FLOW ACROSS PARTS OF NW TX/WRN OK/WRN KS.
OUTFLOW BOUNDARY FROM OVERNIGHT MCS IN N TX APPEARS TO BE DISSIPATING...
BUT WRN PART OF THIS FEATURE MAY REMAIN A FACTOR IN CONVECTIVE
INITIATION LATER TODAY IN WRN OK/THE TX PNHDL/SW KS. WARM FRONT
FARTHER S ACROSS W CNTRL TX SHOULD ALSO WEAKEN AND DRIFT N.
FARTHER N...PART OF SD SURFACE WAVE WILL TRACK ENE WITH NRN STREAM
IMPULSE INTO MN...BUT TROUGHING WILL LIKELY STRENGTHEN OVER SD ONCE
AGAIN LATE IN THE PERIOD WITH APPROACH OF UPPER SYSTEM NOW OVER
WA/ID.
...WRN TX NNEWD INTO SW KS...
STEEP LOW TO MID LEVEL LAPSE RATES AND RICH MOISTURE SUPPLY
APPARENT ON 12Z SOUNDINGS ACROSS REGION INDICATE VERY FAVORABLE
THERMODYNAMIC ENVIRONMENT FOR SUPERCELLS. WHILE CIN WILL BE A
SIGNIFICANT FACTOR WITH SWD EXTENT /PARTICULARLY OVER SW TX/...
DECIDED SE COMPONENT TO LOW LEVEL FLOW UP THE RIO GRANDE VLY WILL
ENHANCE UPSLOPE FLOW/CONVERGENCE. AS PREVIOUSLY NOTED...WEAK
RIDGING ALOFT SUGGESTS THAT UPPER LEVEL FORCING WILL BE NEUTRAL AT
BEST. BUT GIVEN DEGREE OF AFTERNOON SURFACE-BASED INSTABILITY
/SBCAPE AOA 4000 J/KG/...AND 45-50 KT DEEP LAYER SHEAR ASSOCIATED
WITH SRN STREAM JET...SETUP WILL BE SUPPORTIVE OF NUMEROUS DISCRETE
SUPERCELLS WITH LARGE HAIL/HIGH WINDS AND TORNADOES.
...N CNTRL KS INTO CNTRL AND ERN NEB/SE SD/WRN IA...
A SOMEWHAT SEPARATE FOCUS FOR SEVERE STORMS THIS PERIOD EXPECTED TO
DEVELOP INVOF SD SURFACE WAVE AND ASSOCIATED TROUGH EXTENDING S
INTO NRN KS. BOUNDARY LAYER MOISTURE..WHILE SOMEWHAT LIMITED OVER
REGION ATTM...SHOULD INCREASE OVER REGION THROUGH THE DAY BOTH AS
A RESULT OF DOWNWARD MIXING AND CONTINUED LOW LEVEL ADVECTION. MID
LEVEL TEMPERATURES ARE SEVERAL DEGREES COOLER HERE THAN ACROSS THE
SRN PLNS. AS A RESULT...SURFACE HEATING SHOULD BOOST SBCAPE TO AOA
3000 J/KG. COUPLED WITH 50-60 KT MID LEVEL WSWLY FLOW AND
SUSTAINED CONVERGENCE...SUPERCELLS WITH HAIL/HIGH WINDS AND PERHAPS
A COUPLE TORNADOES EXPECTED THIS AFTERNOON/EARLY TONIGHT. THIS
ACTIVITY SHOULD EVOLVE INTO AN MCS LATER TONIGHT. PART OF THE MCS
MAY MOVE E ACROSS IA/NRN MO AND INTO WRN IL BY DAWN. AT THE SAME
TIME...SOME UPSTREAM/BACK-BUILDING DEVELOPMENT MAY ALSO OCCUR SWWD
INTO PARTS OF SRN NEB/NRN KS AS LOW LEVEL JET/MOISTURE INFLUX
INCREASE OVER THAT REGION.
