DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 082000
SWODY1
SPC AC 081958

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT SAT JUN 08 2013

VALID 082000Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL AND
SRN PLAINS...

...CENTRAL/SRN PLAINS THIS AFTN/EVE...
EARLY AFTERNOON SURFACE ANALYSIS SHOWED AN AREA OF LOW PRESSURE
LOCATED OVER CENTRAL SD WITH A FRONT TRAILING SSWWD THROUGH CENTRAL
NEB INTO SWRN KS /INVOF A SECOND LOW LOCATED NEAR THE SWRN KS/SERN
CO BORDER/...WHILE A DRY LINE THEN EXTENDED SWD ACROSS FAR ERN NM.

THE AIR MASS HAS BECOME MODERATELY UNSTABLE ALONG THE SOUTH CENTRAL
NEB/NORTH CENTRAL KS BORDER SWWD TO THE OK/TX PANHANDLES...AND SWD
ALONG AND E OF THE DRY LINE. FARTHER NEWD...EXTENSIVE
CLOUDS/PRECIPITATION OVER ERN NEB INTO WRN IA HAVE LIMITED STRONGER
DESTABILIZATION. THIS LATTER AREA WILL HAVE A LOW POTENTIAL FOR
STRONGER STORMS LATE THIS AFTERNOON TO POTENTIALLY EARLY EVENING.
HOWEVER...A SEVERE WEATHER THREAT CANNOT BE RULED OUT AFTER 09/00Z
AS STRONGER FORCING FOR ASCENT WITH THE DIGGING SHORTWAVE TROUGH
SUPPORTS EXPECTED NEB/NRN KS STORMS TO MOVE INTO SWRN IA...DESPITE
THE PRESENCE OF WEAKER INSTABILITY. EFFECTIVE BULK SHEAR OF 25-35
KT INTO SWRN IA WOULD SUPPORT STORM ORGANIZATION WITH DAMAGING WINDS
AND/OR HAIL POSSIBLE. THUS...DESPITE THE PRESENCE OF EXTENSIVE
CLOUDS/PRECIPITATION AT THIS TIME INTO WRN IA...THE SLIGHT RISK AND
SEVERE PROBABILITIES WILL BE MAINTAINED INTO IA WITH THIS OUTLOOK
ISSUANCE.

OTHERWISE...THE 1630Z FORECAST REMAINS ON TRACK WITH THE POTENTIAL
FOR STORM DEVELOPMENT THIS AFTERNOON/EVENING FROM CENTRAL NEB
THROUGH SWRN KS TO W TX NEAR THE SURFACE BOUNDARIES...WHERE THE AIR
MASS IS BECOMING SUFFICIENTLY SHEARED AND MODERATELY UNSTABLE.

...FAR NERN-EAST CENTRAL NC THIS AFTN...
A FEW STORMS REMAIN POSSIBLE YET THIS AFTERNOON /1-2 HR/ INVOF A
NE-SW ORIENTED ZONE OF LOW LEVEL CONFLUENCE MOVING THROUGH THIS
REGION. TRENDS IN REGIONAL RADAR IMAGERY SHOWED WEAKENING STORM
INTENSITIES...AND THUS HAVE REMOVED LOW SEVERE PROBABILITIES FROM
THIS REGION.

..PETERS.. 06/08/2013

.PREV DISCUSSION... /ISSUED 1130 AM CDT SAT JUN 08 2013/

...SYNOPSIS...
WY SHORTWAVE TROUGH WILL FURTHER AMPLIFY SEWD INTO THE CNTRL PLNS
THIS EVE AND INTO THE LWR MO VLY TNGT/EARLY SUN AS A FLAT RIDGE
PERSISTS OVER THE WRN GRT BASIN/PACIFIC NW. FARTHER E...MODERATE SW
TO WSW FLOW WILL PREVAIL OVER THE S CNTRL AND ERN U.S...WITH
SHORTWAVE TROUGH OVER VA/NC.

THE WY TROUGH WILL MAINTAIN WEAK CYCLOGENESIS OVER NEB TODAY...WITH
THE LOW REACHING WRN IA EARLY SUN. THE ATTENDANT COLD FRONT SHOULD
ACCELERATE SSE ACROSS THE CNTRL HIGH PLNS TODAY...AND MORE SLOWLY
E/SE ACROSS THE CNTRL PLNS/MID-MO VLY BY THROUGH TNGT. FARTHER
S...LEE TROUGH/DRY LINE SHOULD MIX E INTO SW KS...THE OK-TX
PANHANDLES...AND SW TX BY LATE AFTN.

THE PLNS SHORTWAVE TROUGH WILL BE THE MAIN FOCUS FOR STRONG/SVR
TSTMS THIS PERIOD...ALTHOUGH A LIMITED SVR POTENTIAL ALSO WILL
ACCOMPANY VA/NC IMPULSE.

...CNTRL/SRN PLNS THIS AFTN/EVE...
AMPLIFYING UPR SYSTEM WILL PROVIDE FAVORABLE WIND FIELD AND
LARGE-SCALE ASCENT FOR SVR TSTMS OVER A LARGE PART OF THE CNTRL PLNS
AND NWRN PARTS OF THE SRN PLNS THIS PERIOD...BUT EXTENT AND
INTENSITY OF ASSOCIATED THREAT WILL BE LIMITED BY MODEST MOISTURE
AVAILABILITY.

SCTD...MAINLY ELEVATED TSTMS SHOULD CONTINUE TO MOVE/DEVELOP E
ACROSS CNTRL/ERN NEB TODAY...IN ZONE OF DCVA/WAA AHEAD OF MAIN UPR
VORT. THIS ACTIVITY MAY EVOLVE INTO A BAND OR TWO OF SUSTAINED
STORMS/EMBEDDED SUPERCELLS WITH A THREAT FOR SVR WIND/MARGINALLY SVR
HAIL...ESPECIALLY IN CNTRL NEB WHERE THE GREATEST BUOYANCY SHOULD
EXIST.

A SOMEWHAT MORE SUBSTANTIAL WIND/HAIL THREAT MAY DEVELOP THIS AFTN
THROUGH EARLY TNGT FARTHER SW ACROSS A LARGE PART OF KS INTO THE
OK-TX PANHANDLES...WRN OK AND W TX. SFC HEATING ALONG KS COLD
FRONT...AND ALONG DRY LINE FARTHER S...SHOULD YIELD SBCAPE AOA
1500-2000 J/KG...WITH AVERAGE SFC DEWPOINTS IN THE UPR 50S TO AROUND
60 F.

WHILE THE STRONGEST MID/UPR-LVL WINDS WITH THE UPR TROUGH WILL
REMAIN WELL W AND N OF WARM SECTOR...AMPLE DEEP SHEAR /WITH
CONSIDERABLE DIRECTIONAL VEERING/...WILL EXIST FOR SUPERCELLS. THE
TORNADO THREAT REMAINS UNCERTAIN. LOW-LVL DIRECTIONAL SHEAR WILL BE
MAXIMIZED NEAR 30-40 KT SLY LLJ OVER CNTRL/NE KS...BUT MID/UPR-LVL
FLOW OVER THAT REGION WILL BE RELATIVELY WEAK. IN CONTRAST...ALONG
THE DRY LINE...LOW-LVL TURNING WILL REMAIN MINIMAL UNTIL THE LLJ
STRENGTHENS TNGT...ALTHOUGH COMPARATIVELY STRONGER MID/UPR FLOW WILL
EXIST FOR MORE SUSTAINED UPDRAFTS.
IN ANY CASE...SIZABLE TEMP-DEWPOINT SPREADS SUGGEST LIKELIHOOD FOR
SUBSTANTIAL STORM OUTFLOW AND EVOLUTION INTO LINES THAT POSE MAINLY
A WIND/HAIL THREAT.

...ERN NC/SE VA THIS AFTN...
VA/NC SHORTWAVE IMPULSE WILL CONTINUE STEADILY NEWD...MOVING OFF THE
MID ATLANTIC CST BY EARLY TNGT. IN THE MEAN TIME...SFC HEATING AND
ASCENT WITH IMPULSE SHOULD FOSTER INCREASING TSTMS IN ASSOCIATED
AXIS OF LOW-LVL CONFLUENCE. WHILE REGION HAS SOMEWHAT DRIED SINCE
YESTERDAY...A RESIDUAL BELT OF MODERATE PW /AROUND 1.50 INCHES/ WILL
REMAIN IN PLACE IN WAKE OF TS ANDREA. COUPLED WITH 30-40
KT...UNIDIRECTIONAL...WSWLY LOW-MID TROPOSPHERIC FLOW...SETUP MAY
YIELD SCTD STORMS/SHORT LINES WITH MARGINALLY SVR HAIL/WIND.

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