DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 072002
SWODY1
SPC AC 072000

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT SUN APR 07 2013

VALID 072000Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON THROUGH TONIGHT
FOR NW OK...MUCH OF KS...AND WRN/CENTRAL MO...

...WESTERN/NORTHERN OK AND KS TO CENTRAL MO THROUGH TONIGHT...
ONLY MINIMAL CHANGES TO EXISTING CONVECTIVE OUTLOOK...WITH LITTLE
FLUCTUATION IN FORECAST REASONING AS PER PRIOR OUTLOOK DISCUSSION
BELOW. OF INITIAL CONCERN IS ONGOING TSTM CLUSTER/SUPERCELL ACROSS
SOUTHEAST KS INTO SOUTHWEST MO...REFERENCE SEVERE TSTM WATCH 83.
REGARDING THE SOURCE REGION AIRMASS...THE 18Z OBSERVED SOUNDING FROM
LAMONT OK IS INDICATIVE OF CONSIDERABLE MOISTENING WITHIN THE LOWEST
1 KM SINCE 11Z...WITH VERY STEEP MID LEVEL LAPSE RATES AND MUCAPE OF
AROUND 1500 J/KG. OTHERWISE...INITIALLY HIGH-BASED TSTMS SHOULD
CONTINUE TO GRADUALLY INCREASE ACROSS WEST-CENTRAL KS THROUGH LATE
AFTERNOON/EARLY EVENING...WITH MORE UNCERTAIN DEVELOPMENT
PROGRESSIVELY FARTHER SOUTH ACROSS WESTERN OK/FAR NORTHWEST TX.

..GUYER.. 04/07/2013

.PREV DISCUSSION... /ISSUED 1129 AM CDT SUN APR 07 2013/

...SYNOPSIS...
A STRONG MIDLEVEL SHORTWAVE TROUGH WITH AN ASSOCIATED 100 KT JET
STREAK WILL DIG SEWD TO CA/NV THROUGH TONIGHT...WHILE GRADUAL
DOWNSTREAM HEIGHT RISES OCCUR OVER THE LOWER MS VALLEY AND SE
STATES. IN BETWEEN...A SERIES OF LOW-AMPLITUDE SPEED MAXIMA WILL
PROGRESS FROM THE FOUR CORNERS TO THE OH VALLEY AND LOWER GREAT
LAKES. THE LARGELY WLY FLOW REGIME WILL CONTINUE TO SUPPORT LEE
CYCLOGENESIS ACROSS THE HIGH PLAINS...AS WELL AS LOW-LEVEL MOISTURE
TRANSPORT NWD ACROSS THE SRN/CENTRAL PLAINS.

...NW OK/KS TO CENTRAL MO THROUGH TONIGHT...
12Z SOUNDINGS AND RECENT SURFACE ANALYSES CONFIRM ONGOING LOW-LEVEL
MOISTURE RETURN INTO TX/OK/KS FROM THE WRN GULF BASIN...THOUGH
OBSERVATIONS SUGGEST THAT SHORT-TERM MODEL FORECASTS MAY BE A COUPLE
DEGREES TOO HIGH WITH THE BOUNDARY LAYER DEWPOINTS THIS AFTERNOON.
MEANWHILE...THE EML NOTED IN THE AMA/MAF SOUNDINGS WILL CONTINUE TO
OVERSPREAD NW TX AND WRN OK...LIKELY PROVIDING A SUFFICIENT CAP TO
LIMIT CONVECTIVE INITIATION PROSPECTS ALONG THE WRN OK/NW TX DRYLINE
AND NEAR THE WEAK SURFACE CYCLONE. THE N EDGE OF THE WARMER EML
RESIDES BETWEEN AMA AND DDC...AND EXTRAPOLATION SUGGESTS THAT THE
MORE PROBABLE AREA FOR CONVECTIVE INITIATION THIS AFTERNOON/EVENING
WILL BE NEAR AND N OF THE KS/OK BORDER.

MODIFIED FORECAST SOUNDINGS...ACCOUNTING FOR AFTERNOON TEMPS IN THE
LOW-MID 70S WITH SOME CLOUDS AND BOUNDARY LAYER DEWPOINTS OF 58-60
F...SUPPORT MLCAPE APPROACHING 2000 J/KG WITH ONLY SMALL CIN ACROSS
NW OK AND ADJACENT AREAS OF KS. ADDITIONALLY... WATER VAPOR IMAGERY
SUGGESTS THE PRESENCE OF AN EMBEDDED SPEED MAX ALOFT OVER NRN NM AS
OF MID MORNING...WHICH SHOULD REACH THE NW OK/SW KS BORDER REGION BY
THIS EVENING. THUS...THE EXPECTATION FOR AT LEAST ISOLATED
THUNDERSTORM DEVELOPMENT NEAR OR N OF THE OK/KS BORDER APPEARS
REASONABLE BY LATE AFTERNOON. STORMS THAT FORM IN THIS AREA WILL
LIKELY BECOME SUPERCELLS GIVEN THE MODERATE INSTABILITY AND
EFFECTIVE BULK SHEAR NEAR 50 KT...AND BE CAPABLE OF PRODUCING
ISOLATED VERY LARGE HAIL AND DAMAGING GUSTS. A TORNADO OR TWO WILL
BE POSSIBLE THIS EVENING WITH ANY SUPERCELLS ON THE N SIDE OF THE
RICHER LOW-LEVEL MOISTURE AND AS LOW-LEVEL SHEAR INCREASES THIS
EVENING IN CONJUNCTION WITH A STRENGTHENING LLJ.

OTHERWISE...A NWD INCREASE IN MOISTURE AND THE ASSOCIATED LOW-LEVEL
WAA REGIME SHOULD PROMOTE THE DEVELOPMENT OF THUNDERSTORM CLUSTERS
BY THIS EVENING AND CONTINUE THROUGH TONIGHT ACROSS CENTRAL/NE KS
INTO MO...WITH AN ATTENDANT RISK FOR ISOLATED LARGE HAIL AND
DAMAGING WINDS.

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