DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 082002
SWODY1
SPC AC 082000

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT WED MAY 08 2013

VALID 082000Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN CO...WRN AND CNTRL
KS...WRN AND CNTRL OK INTO NWRN TX...

...ERN CO...WRN THROUGH CNTRL KS...WRN AND CNTRL OK AND NWRN TX...

ONLY MINOR ADJUSTMENTS HAVE BEEN MADE FOR THIS UPDATE...MAINLY TO
EXPAND SLIGHT RISK A LITTLE FARTHER WEST AND NORTH INTO ERN CO AND
THE OK PANHANDLE TO ACCOUNT FOR STORMS DEVELOPING IN UPSLOPE REGIME
AND SPREADING INTO THE HIGH PLAINS. OTHER STORMS SHOULD DEVELOP SWD
ALONG DRYLINE ACROSS WRN OK INTO NWRN TX INTO THE EVENING. VERTICAL
WIND PROFILES WITH 30-40 KT EFFECTIVE SHEAR SUPPORT ORGANIZED
MULTICELLS AND SOME SUPERCELL STRUCTURES. DAMAGING WIND AND LARGE
HAIL APPEAR TO BE THE PRIMARY THREATS. ACTIVITY MAY EVENTUALLY
CONGEAL INTO ONE OR MORE CLUSTERS AS IT CONTINUES EWD THROUGH THE
SRN PLAINS OVERNIGHT SUPPORTED BY A STRENGTHENING NOCTURNAL LLJ.

..DIAL.. 05/08/2013

.PREV DISCUSSION... /ISSUED 1131 AM CDT WED MAY 08 2013/

...SYNOPSIS...
MID-ATLANTIC UPR LOW IS EXPECTED TO DRIFT SLOWLY NNE INTO ERN PA BY
THE END OF THE PERIOD...WHILE FOUR CORNERS SYSTEM REMAINS MORE OR
LESS STNRY WHILE DEVOLVING INTO SEVERAL ELONGATED...PROGRESSIVE VORT
MAXIMA.

AT THE SFC...LOOSELY-ORGANIZED LOW NOW CENTERED OVER SW KS/THE OK
PANHANDLE SHOULD REMAIN NEARLY STNRY TODAY BEFORE EDGING E/SE ACROSS
CNTRL KS/WRN OK AS AN ELONGATED AREA OF LOW PRESSURE TNGT/EARLY THU.
IN THE EAST...DIFFUSE/MULTI-CENTERED LOW NOW OVER WV/MD IS EXPECTED
TO DRIFT SLOWLY NNE WITH TIME...WITH LITTLE CHANGE IN STRENGTH.

AN OUTFLOW BOUNDARY/WARM FRONT EXTENDING ESE FROM THE PLNS LOW...AND
A LEE TROUGH/DRY LINE TRAILING SSW FROM IT...WILL BE THE MAIN FOCI
FOR POTENTIAL SVR TSTM DEVELOPMENT THIS PERIOD.

...CNTRL/SRN PLNS THIS AFTN THROUGH EARLY THU...
WEAK TO LOCALLY MODERATE LARGE-SCALE ASCENT SHOULD CHARACTERIZE MUCH
OF THE CNTRL AND SRN PLNS THIS PERIOD AS WEAK DISTURBANCES TRACK ENE
WITH SE QUADRANT OF ELONGATING UPR LOW NOW OVER THE FOUR CORNERS. AT
THE SAME TIME...AT LWR LVLS...PERSISTENT S-SSELY FLOW WILL MAINTAIN
MODEST MOISTURE RETURN E OF DRY LINE AND S OF OUTFLOW BOUNDARY/WARM
FRONT...WITH SFC DEWPOINTS EXPECTED TO RANGE FROM THE UPR 50S IN FAR
SRN KS TO AROUND 60 F IN NW TX BY LATE IN THE DAY.

COMBINATION OF SLOWLY INCREASING MOISTURE...STRONG SFC
HEATING...MODEST LARGE-SCALE ASCENT...AND CONVERGENCE ALONG SFC
BOUNDARIES SHOULD PROMOTE DEVELOPMENT OF STRONG STORMS BY MID TO
LATE AFTN AS SBCAPE INCREASES TO BETWEEN 1500 TO 2500 J/KG. OTHER
STORMS MAY DEVELOP E/SE FROM THE HIGHER TERRAIN IN S CNTRL
CO...WHERE LOW-LVL UPSLOPE FLOW WILL PERSIST N OF SFC LOW.

30-35 KT WSWLY 500 MB FLOW ATOP 25 KT SLY LOW-LVL JET STREAM WILL BE
FAVORABLE FOR SUSTAINED STORMS/SUPERCELLS. GIVEN THE THERMODYNAMIC
ENVIRONMENT...THESE WILL YIELD BOTH LARGE HAIL AND LOCALLY DMGG
WIND. TORNADOES MAY ALSO OCCUR...ALTHOUGH ANY SUCH OCCURRENCE LIKELY
WILL BE TIED TO LOCALLY FAVORABLE STORM/BOUNDARY INTERACTIONS GIVEN
SIZABLE TEMP-DEWPOINT SPREADS.

THE TSTMS LIKELY WILL EVOLVE INTO SEVERAL PERSISTENT CLUSTERS THIS
EVE...WITH A CONTINUED RISK FOR SVR HAIL/WIND...GIVEN MULTIPLE
SOURCES OF LOW-LVL ASCENT...ABSENCE OF A STRONG UPR-LVL FEATURE TO
FOCUS DEVELOPMENT...AND INCREASING MOISTURE /PW TO 1.25 INCHES/. THE
SVR THREAT SHOULD...HOWEVER...DECREASE WITH NOCTURNAL COOLING LATER
TNGT.

...MID ATLANTIC THIS AFTN...
COOL POCKET ALOFT ASSOCIATED WITH ERN STATE UPR LOW HAS SHRUNKEN
RELATIVE TO RECENT DAYS AND NOW APPEARS TO BE CENTERED OVER MD/NRN
VA. PART OF THIS FEATURE MAY PIVOT NWD INTO PA TODAY... WHERE IT
WILL OVERSPREAD LINGERING CURRENT OF MOIST...ESELY LOW-LVL FLOW
ALONG AND N OF WEAK OCCLUSION/SFC TROUGH. WITH SFC DEWPOINTS
REMAINING IN THE UPR 50S TO AROUND 60F...AND WITH MODEST...LARGELY
UNIDIRECTIONAL DEEP SELY FLOW CONTINUING...SETUP MAY YIELD A FEW
INSTANCES OF MARGINALLY SVR HAIL...ESPECIALLY FROM CNTRL NJ AND THE
NYC AREA WNW INTO CNTRL PA.

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