SPC AC 052015
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0315 PM CDT MON APR 05 2010
VALID 052000Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS ERN KY TO NRN MO AND
SRN WI...SWWD ACROSS IA/KS TO PORTIONS NW OK...
--- UPDATES ---
...SRN INDIANA TO WRN KY...
15% PROBABILITIES EXTENDED ESEWD ALONG AND JUST S OF FRONTAL ZONE
ACROSS THIS REGION. VIS SATELLITE TRENDS INDICATE INCREASING
COVERAGE/DEPTH OF TCU IN THIS CORRIDOR...IN ENVIRONMENT THAT
MODIFIED RAOBS AND RUC SOUNDINGS INDICATE VERY WEAK MLCINH AND
MLCAPE COMMONLY 1500-2000 J/KG FROM NOW THROUGH ABOUT 23Z. VWP AND
FCST SOUNDINGS ALSO INDICATE FAVORABLE SHEAR WITH EFFECTIVE VALUES
AROUND 50 KT OVER SRN PORTIONS IL/INDIANA...TO 35-40 KT ACROSS ERN
KY. SUBTLE SHORTWAVE TROUGH -- EVIDENT IN MOISTURE CHANNEL IMAGERY
AND VWP/PROFILER DATA OVER NRN MO...ALSO WILL MOVE TOWARD THIS
REGION DURING NEXT SEVERAL HOURS WITH RELATED SUBTLE INCREASES
LIKELY IN BOTH MID-UPPER GRADIENT FLOW AND LARGE-SCALE
ASCENT/DESTABILIZATION ALOFT.
...IA...NRN MO...IL...
REF WWS 48...49 AND RELATED MESOSCALE DISCUSSIONS FOR NEAR-TERM
THREAT ACCOMPANYING CONVECTION N OF SFC WARM FRONT ACROSS PORTIONS
NRN MO AND IA....AND OVER PORTIONS SRN L/ERN MO RESPECTIVELY. VERY
CONDITIONAL BUT SIGNIFICANT SVR THREAT FOR MORE SFC-BASED
SUPERCELLS...WITH ACCOMPANYING TORNADO/HAIL/WIND POTENTIAL...STILL
MAY DEVELOP LATER THIS AFTERNOON OVER SOME OF WW 48 AREA PER
PREVIOUS OUTLOOKS.
...CENTRAL KS TO NW OK...
SLGT ADJUSTMENTS TO PROBABILISTIC AND CATEGORICAL LINES BASED ON
OBSERVATIONAL TRENDS...WITH DRYLINE EXPECTED TO RETREAT WWD FROM
PRESENT POSITION LATE AFTERNOON INTO EARLY EVENING. THIS THREAT
ALSO APPEARS STRONGLY CONDITIONAL...WHEREBY STG CAPPING WILL LIMIT
CONVECTIVE COVERAGE...BUT POTENTIAL REMAINS FOR ISOLATED SUPERCELL
TO DEVELOP LATE THIS AFTERNOON...WITH ANY SVR MODE POSSIBLE DURING
ITS LIFESPAN.
..EDWARDS.. 04/05/2010
.PREV DISCUSSION... /ISSUED 1119 AM CDT MON APR 05 2010/
A COMPLEX AND RELATIVELY LOW CONFIDENCE FORECAST SCENARIO WILL
DEVELOP TODAY. BROAD SOUTHWESTERLY MID LEVEL FLOW IS IN PLACE
ACROSS THE CENTRAL PLAINS AND MIDWEST STATES...WHILE SOUTHERLY LOW
LEVEL MOISTURE RETURNS TO A LARGE PART OF THE CENTRAL UNITED STATES.
WIDESPREAD MOISTURE AND COOL TEMPERATURES ALOFT WILL LEAD TO
MODERATE INSTABILITY ACROSS MUCH OF THE CENTRAL/SOUTHERN
PLAINS...MS...AND OH VALLEYS. HOWEVER...OBSERVATIONAL AND MODEL
DATA LEND LOW CONFIDENCE IN CONVECTIVE EVOLUTION IN MOST AREAS.
...IL/IA/MO/NEB/KS...
SCATTERED ELEVATED THUNDERSTORMS ARE CONTINUING THIS MORNING OVER
NORTHWEST MO/NORTHEAST KS IN REGION OF LOW LEVEL WARM ADVECTION AND
MOISTENING. THESE STORMS MAY PERSIST MUCH OF THE DAY AS THEY LIFT
NORTHEASTWARD INTO IA. THEIR ASSOCIATED OUTFLOW BOUNDARY WILL ALSO
LIFT NORTHWARD TO NEAR THE MO/IA BORDER BY LATE AFTERNOON. WEAK MID
LEVEL HEIGHT FALLS LATER TODAY COMBINED WITH STRONG DAYTIME HEATING
AND DESTABILIZATION WILL HELP TO PROMOTE THE POTENTIAL FOR NEW
THUNDERSTORM INITIATION AFTER 21Z ALONG THE BOUNDARY. FORECAST
SOUNDINGS FROM NAM/GFS/RUC/NAMKF/NMM4 ALL SUGGEST A VERY POTENT
COMBINATION OF MODERATE INSTABILITY...WEAK CAP...AND LARGE LOOPING
HODOGRAPHS ALONG AN AXIS FROM THE NORTHEAST KS/SOUTHEAST NEB BORDER
TO NORTH OF IRK. THERE APPEARS TO BE A NARROW CORRIDOR WHERE
POTENTIAL EXISTS FOR PERSISTENT SUPERCELLS WITH VERY LARGE HAIL AND
STRONG TORNADOES. HOWEVER...MODEL GUIDANCE VARIES CONSIDERABLY
REGARDING THE PROBABILITY OF SURFACE-BASED CONVECTION. SERIOUSLY
CONSIDERED UPGRADE TO MODERATE RISK IN THIS REGION...BUT WILL
MAINTAIN SLIGHT AND MONITOR OBSERVATIONAL TRENDS THIS AFTERNOON.
JUST NORTH OF THE BOUNDARY...SLIGHTLY ELEVATED STORMS ARE EXPECTED
WITH LARGE HAIL LIKELY ACROSS MUCH OF IA INTO NORTHERN IL TONIGHT.
MODELS ALSO SUGGEST THE POTENTIAL FOR REPEAT CLUSTERS OF STORMS IN
THIS AREA OVERNIGHT.
...MO/IL/IND...
ABUNDANT MOISTURE/INSTABILITY ARE NOW IN PLACE OVER THE MID MS AND
LOWER OH VALLEYS...WITH DEWPOINTS IN THE 60S AND AFTERNOON MLCAPE
VALUES EXPECTED TO BE OVER 1000 J/KG. THIS AREA APPEARS TO BE UNDER
SHORTWAVE RIDGING THROUGH MUCH OF THE DAY...WHICH WILL LIMIT
COVERAGE OF THUNDERSTORMS. HOWEVER...WEAK CAP AND TRENDS IN CU
FIELDS ACROSS THE AREA SUGGEST THE RISK OF AT LEAST ISOLATED
STORMS...ESPECIALLY ALONG AN AXIS FROM CENTRAL IL INTO SOUTHERN
IND/CENTRAL KY. IF STORMS CAN INITIATE...POTENTIAL WILL EXIST FOR
ORGANIZED/SUPERCELL STORMS CAPABLE OF HAIL AND DAMAGING WINDS.
...KS/OK...
A STRONG DRYLINE IS FORECAST TO BECOME ESTABLISHED THIS AFTERNOON
AND EVENING FROM CENTRAL KS INTO WESTERN OK. AT THIS TIME...ALL
NUMERICAL GUIDANCE INDICATES THAT CONVECTIVE INITIATION WILL NOT
OCCUR ALONG THIS CORRIDOR. HOWEVER...STRENGTH OF HEATING TO WEST OF
DRYLINE...DEGREE OF INSTABILITY IMMEDIATE EAST OF DRYLINE...AND A
RELATIVELY WEAK CAP DURING MAX HEATING ALL SUGGEST THAT THE RISK OF
AN ISOLATED STORM OR TWO REMAINS. IF A STORM CAN FORM...LOW LEVEL
VERTICAL SHEAR AND THERMODYNAMIC PROFILES ARE QUITE FAVORABLE FOR
SUPERCELL STORMS CAPABLE OF VERY LARGE HAIL AND TORNADOES. WILL
MAINTAIN THE SLIGHT RISK ALONG THIS AXIS FOR THIS HIGHLY CONDITIONAL
BUT POTENTIALLY SIGNIFICANT SCENARIO.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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