DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 271608
SWODY1
SPC AC 271607

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
ISSUED BY 15TH OWS SCOTT AIR FORCE BASE IL
1107 AM CDT THU MAR 27 2014

VALID 271630Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS ERN PARTS OF KS AND OK INTO MID
MS VALLEY AND OZARK PLATEAU...

...SYNOPSIS...

A PROGRESSIVE...LOW-AMPLITUDE PATTERN WILL EXIST OVER THE CONUS
THROUGH THE D1 PERIOD. WITHIN THIS REGIME...A POLAR-BRANCH
SHORT-WAVE TROUGH AND ASSOCIATED 70-80 KT MIDLEVEL JET STREAK WILL
TRANSLATE FROM THE CNTRL/SRN PLAINS ENEWD INTO THE GREAT LAKES AND
OH VALLEY BY 28/12Z. THIS SYSTEM WILL BE ATTENDED BY A BROAD 50-60+
KT SWLY LLJ WHICH WILL CORRESPONDINGLY MIGRATE FROM LOWER ELEVATIONS
OF THE GREAT PLAINS AND OZARKS TO UPPER OH VALLEY AND NERN U.S. BY
THE END OF THE PERIOD.

AT THE SURFACE...LOW PRESSURE OVER N-CNTRL KS WILL UNDERGO GRADUAL
WEAKENING WHILE DEVELOPING NEWD TO ERN IA BY 28/00Z...PRIOR TO
REACHING NRN LOWER MI BY DAYBREAK FRIDAY. A DRYLINE EXTENDING SWD
FROM THIS LOW WILL MIX EWD INTO ERN PARTS OF KS/OK BY AFTERNOON
WHILE BEING GRADUALLY OVERTAKEN FROM THE N BY A COLD FRONT ADVANCING
SEWD THROUGH THE CNTRL INTO SRN PLAINS. THE SRN EXTENSION OF THE
DRYLINE WILL LIKELY REACH THE I-35 CORRIDOR OF TX BEFORE STALLING IN
RESPONSE TO CYCLOGENESIS OVER N-CNTRL TX TONIGHT.

...ERN PARTS OF KS/OK INTO THE MID MS VALLEY AND OZARK PLATEAU THIS
AFTERNOON INTO TONIGHT...

THE POLEWARD FLUX OF HEAT AND MOISTURE WILL BE MAINTAINED TODAY
ALONG THE ABOVE-MENTIONED LLJ AXIS WITH WARM SECTOR DEWPOINTS RISING
INTO THE 50S OVER ERN KS/WRN MO...AND UPPER 50S TO LOWER 60S ACROSS
PARTS OF ERN OK AND AR. THIS MOISTURE INCREASE WILL BE SURMOUNTED BY
A WELL-DEFINED EML WITH AFTERNOON MLCAPE VALUES APPROACHING 500-1200
J/KG WITHIN THE NWD-EXPANDING WARM SECTOR.

CLEARING SKIES IN CENTRAL AND EASTERN KS ALLOWING FOR FURTHER
DESTABILIZATION IN LOW LEVEL...SURFACE-BASED STORM DEVELOPMENT WILL
BECOME INCREASINGLY LIKELY IN THE 18-21Z TIME FRAME FROM THE
VICINITY OF THE SURFACE LOW OVER SWRN IA OR NWRN MO SWWD ALONG THE
COLD FRONT-DRYLINE OCCLUSION INTO ERN KS AND SW MO. THIS COUPLED
WITH STRONG SHORTWAVE WILL ALLOW THE LINEAR NATURE OF LOW-LEVEL
FORCING MECHANISM AND ITS ALIGNMENT TO THE DEEP-LAYER SHEAR VECTOR
WOULD INDICATE THAT STORMS SHOULD EVOLVE INTO LINE SEGMENTS OR A
CONTINUOUS BAND WITH HAIL AND DAMAGING WINDS BEING THE PRIMARY
HAZARDS. AS THESE STORMS SPREAD EWD/SEWD INTO THE MID MS VALLEY AND
OZARK PLATEAU OVERNIGHT...EXPECT THE SEVERE WEATHER THREAT TO
GRADUALLY DIMINISH OWING TO THE COOLING AND RESULTANT STABILIZATION
OF THE BOUNDARY LAYER.

DIURNAL STORM DEVELOPMENT SWD ALONG THE DRYLINE INTO ERN OK/WRN AR
REMAINS MORE UNCERTAIN GIVEN THE TENDENCY FOR THE HEIGHT
FALLS/FORCING FOR ASCENT ASSOCIATED WITH THE MIDLEVEL TROUGH TO
SHIFT AWAY FROM THE REGION DURING THE TIME OF PEAK HEATING. AS
SUCH...INITIATION WILL BE HEAVILY RELIANT ON BOUNDARY LAYER HEATING
ALONG AND WEST OF THE DRYLINE. SHOULD SURFACE-BASED STORMS FORM AND
BECOME SUSTAINED...THE COMBINATION OF MODERATE INSTABILITY...50-60
KT OF DEEP-LAYER SHEAR ORIENTED NORMAL TO THE DRYLINE AND MODERATELY
STRONG LOW-LEVEL SHEAR WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF
LARGE HAIL AND A FEW TORNADOES.

...ERN TX INTO THE LOWER MS VALLEY THIS AFTERNOON THROUGH
TONIGHT...

BOTH CONVECTION-ALLOWING AND PARAMETRIZED MODEL GUIDANCE INDICATE AN
INCREASE IN TSTMS TODAY WITHIN THE OPEN WARM SECTOR FROM ERN TX INTO
THE LOWER MS VALLEY. HERE...LOW-LEVEL CONFLUENT FLOW WILL BE
AUGMENTED BY A DEEPER CIRCULATION TIED TO THE COUPLING OF POLAR AND
SUB-TROPICAL-BRANCH JET STREAKS. WHILE THE BOUNDARY LAYER WILL
UNDERGO CONTINUED WARMING AND MOISTENING THROUGH THE PEAK OF THE
DIURNAL HEATING CYCLE...A CONSIDERABLE CAP AT THE BASE OF AN EML
/REFERENCE 12Z SOUNDINGS/ CASTS UNCERTAINTY AS TO WHETHER ANY OF
THESE STORMS WILL TRULY BECOME SURFACE BASED. AS SUCH...THE EXISTING
LOW SEVERE PROBABILITIES WILL BE MAINTAINED IN THIS FORECAST.

..15_OWS.. 03/27/2014

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