DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 171948
SWODY1
SPC AC 171946

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT WED JUL 17 2013

VALID 172000Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN ROCKIES AREA...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE UPPER PENINSULA OF
MI...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NERN STATES...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE CAROLINAS
INCLUDING THE SRN APPALAHIANS AREA...

...DISCUSSION...

HAVE INCLUDED A SLIGHT RISK FOR THE SRN APPALACHIANS AND CAROLINAS
WHERE NUMEROUS STORMS ARE DEVELOPING IN WARM SECTOR...THE MOUNTAINS
AND ALONG SEABREEZE BOUNDARIES. STRONG HEATING OF THE VERY MOIST
SURFACE LAYER HAS STEEPENED LOW-LEVEL LAPSE RATES AND BOOSTED MLCAPE
TO 2500-3000 J/KG. THIS REGION RESIDES WITHIN BELT OF 15-20 KT NELY
DEEP LAYER WINDS ALONG SERN PERIPHERY OF AN UPPER RIDGE. SOME OF THE
STORMS MAY CONSOLIDATE INTO LINE SEGMENTS OR CLUSTERS AS THEY
DEVELOP SWWD WITH A THREAT OF MAINLY ISOLATED DAMAGING WIND GUSTS.

ELSEWHERE...FORECAST APPEARS ON TRACK WITH NO MAJOR CHANGES TO THIS
UPDATE.

..DIAL.. 07/17/2013

.PREV DISCUSSION... /ISSUED 1131 AM CDT WED JUL 17 2013/

...SYNOPSIS...
STRONG...EXPANSIVE...ELONGATED RIDGE WILL PERSIST FROM THE CNTRL/NRN
PLAINS E INTO THE WRN ATLANTIC THROUGH THU AS NM UPR LOW CONTINUES
STEADILY WSWWD. ON THE NWRN EXTENSION OF THE RIDGE...POTENT
SHORTWAVE TROUGH NOW OVER WA/ORE SHOULD SOMEWHAT WEAKEN AS IT
ADVANCES NE INTO CONFLUENT FLOW OVER SRN BC/AB. FARTHER E ACROSS SRN
CANADA...PATTERN WILL BE DOMINATED BY STRENGTHENING WNW FLOW ON SRN
EDGE OF DEEP VORTEX OVER HUDSON BAY. AN AMPLIFYING SHORTWAVE IMPULSE
IN THIS JET...NOW OVER NW ONT...SHOULD CONTINUE E/SE INTO WRN QUE BY
EARLY THU.

COLD FRONT ASSOCIATED WITH THE SRN CANADIAN JET ATTM EXTENDS FROM
CNTRL QUE WSW ACROSS LK SUPERIOR TO THE UPR MS VLY. FROM THERE THE
BOUNDARY CONTINUES GENERALLY W AND NW INTO THE NRN RCKYS. THE WRN
END OF THE FRONT SHOULD REDEVELOP N ACROSS MT LATER TODAY IN
RESPONSE TO THE NWD ADVANCE OF ORE/WA IMPULSE...AND COULD SERVE AS A
FOCUS FOR STRONG TO SVR STORMS OVER THE NRN RCKYS/NRN HI PLNS. THE
ERN PART OF THE FRONT...MEANWHILE...SHOULD ACCELERATE ESE ACROSS
PARTS OF ONT AND QUE. STRONG TO SVR STORMS FORMING ALONG AND AHEAD
OF THE BOUNDARY COULD AFFECT PARTS OF THE NORTHEAST LATER THIS AFTN
AND EVE.

ELSEWHERE...TSTM POTENTIAL SHOULD BE MORE PULSE IN NATURE AND TIED
LARGELY TO WEAK DISTURBANCES ROTATING AROUND THE IMMEDIATE FRINGE OF
THE CNTRL/ERN U.S. RIDGE.

...NRN/ERN WA TO NRN RCKYS/NRN HI PLNS TODAY THROUGH EARLY TNGT...
ADDITIONAL SCTD TSTMS EXPECTED TO FORM OVER NRN AND ERN WA LATER
THIS MORNING ...AND OVER THE HIGHER TERRAIN OF NRN ID AND WRN MT
THROUGH THE AFTN...AS SFC HEATING FURTHER DESTABILIZES REGION
DOWNSTREAM FROM ORE/WA UPR TROUGH. AMPLE MOISTURE /PW AOA 1 INCH/
PRESENT ABOVE RELATIVELY DRY AND WARM BOUNDARY LAYER...COUPLED WITH
STEEP MID-LVL LAPSE RATES AND 40 KT/LARGELY UNIDIRECTIONAL MID-LVL
FLOW...WILL CREATE AN ENVIRONMENT FAVORABLE FOR SUSTAINED
STORMS/SUPERCELLS WITH A RISK FOR SVR WIND AND HAIL. LATER THIS AFTN
INTO THIS EVE...STORMS ALSO MAY FORM/DEVELOP NEWD ACROSS THE PLAINS
OF CNTRL/NRN MT...WHERE LOW-LVL MOISTURE AND UPLIFT WILL BE FOCUSED
INVOF NWD-MOVING FRONT. WHILE LOW-LVL SHEAR SHOULD REMAIN
MODEST...GIVEN THE LIKELY PRESENCE OF DISCRETE STORMS AND BACKED SFC
FLOW NEAR FRONT...THESE MAY POSE A RISK OF A TORNADO IN ADDITION TO
LARGE HAIL/DMGG WIND.

...NRN NY INTO NRN NEW ENGLAND TODAY THROUGH EARLY TNGT...
WEAK SHORTWAVE RIDGING WILL PERSIST TODAY OVER REGION...ALONG WITH
LOW-LVL WAA/MOISTURE TRANSPORT INVOF SHALLOW WARM FRONT IN NRN/ERN
ME. SFC HEATING...TERRAIN CIRCULATIONS...AND WAA TOGETHER MAY
INITIATE SCTD TSTMS OVER PARTS OF ME AND NH THIS AFTN...WHERE
BUOYANCY AND 30+ KT WNWLY DEEP SHEAR MAY PROVE SUFFICIENT FOR A FEW
STORMS WITH SVR WIND/HAIL.

LATER TODAY...ESE ACCELERATION OF QUE COLD FRONT/PREFRONTAL TROUGH
MAY YIELD A BAND OF ADDITIONAL STORMS OVER SRN QUE AND THE ST
LAWRENCE VLY. THIS ACTIVITY COULD APPROACH THE U.S. BORDER LATE IN
THE AFTN...WITH OTHER STORMS CONTINUING TO MOVE/DEVELOP ESE INTO THE
REGION AFTER DARK. GRADUALLY STRENGTHENING WNWLY MID-LVL FLOW /WITH
SPEEDS AROUND 40 KTS BY 00Z/ WILL PROVIDE AMPLE DEEP SHEAR FOR
SUSTAINED STORMS AND PERHAPS A FEW EMBEDDED SUPERCELLS POSING A RISK
FOR SVR WIND...HAIL... AND POSSIBLY A TORNADO. WHILE THE STORMS
COULD PERSIST INTO LATE TNGT...THE SVR THREAT SHOULD GRADUALLY
DIMINISH WITH DIURNAL COOLING AND INCREASING SWD EXTENT.

...UPR MS VLY TO UPR GRT LKS THIS AFTN...
MODERATE DEEPLY UNIDIRECTIONAL W TO WNW FLOW WILL PERSIST ACROSS NRN
MN AND NRN PORTIONS OF WI AND MI TODAY ON SRN EDGE OF THE WLYS.
WHILE THE WLY FLOW WILL SUBSTANTIALLY DECREASE WITH SWD
EXTENT...WATER VAPOR IMAGERY SUGGESTS THAT REGION WILL BE AT LEAST
GLANCED BY THE FAR SRN EDGE OF LOW-AMPLITUDE SHORTWAVE IMPULSE NOW
OVER WRN ONT. WITH STRONG SFC HEATING...EXPECT TSTMS TO FORM THIS
AFTN ALONG STALLED FRONT OVER THE REGION...AND/OR ALONG LAKE BREEZE
BOUNDARIES. UNIDIRECTIONAL FLOW PARALLEL TO THE BOUNDARIES COULD
SUPPORT DEVELOPMENT OF BOTH FORWARD-PROPAGATING LINE SEGMENTS/SMALL
BOWS AND BACK-BUILDING EPISODES FROM CNTRL MN EWD INTO NRN WI AND
UPR MI. WHILE DEEP SHEAR WILL BE MARGINAL FOR SUSTAINED SVR
STORMS...GIVEN DEGREE OF SFC-BASED BUOYANCY /MLCAPE AOA 2500 J PER
KG/...THE ACTIVITY COULD YIELD SCTD INSTANCES OF SVR WIND AND HAIL.

...ERN/SERN STATES THIS AFTN...
WITH LITTLE CHANGE HAVING OCCURRED IN THE LARGE SCALE PATTERN ACROSS
REGION...SFC HEATING SHOULD RESULT IN ANOTHER ROUND OF
SCTD...LARGELY DIURNAL STORMS IN WEAKLY CAPPED ENVIRONMENT ON ERN
AND SRN PERIPHERY OF CNTRL/ERN STATES RIDGE. BASED ON THE CURRENT
SFC DATA AND THE 12Z RAOBS...LOW TO MID-LVL LAPSE RATES SHOULD BE
STEEPEST ALONG AN ARC EXTENDING S/SW FROM WRN PA/WV ALONG THE SRN
APPALACHIANS INTO PARTS OF THE SOUTHEAST...LARGELY COINCIDENT THE
BELT OF STRONGEST /20 KT/ LWR TROPOSPHERIC FLOW. GIVEN EXPECTED
STORM COVERAGE AND ABSENCE OF STRONG LOW-LVL FORCING...SETUP COULD
ONCE AGAIN YIELD A FEW S TO SW-MOVING STORM CLUSTERS WITH AN
ASSOCIATED RISK FOR LOCALLY DMGG WIND AND PERHAPS MARGINALLY SVR
HAIL.

...CNTRL/SRN AZ THIS AFTN/EVE...
ANOMALOUS NLY FLOW WILL PREVAIL AT MID AND UPR LVLS ACROSS AZ TODAY
ON WRN SIDE OF APPROACHING UPR LOW. WHILE SPEEDS SHOULD REMAIN
MODEST...PROFILES WILL BE FAVORABLE FOR SWD PROPAGATION OF STORMS
OFF THE HIGHER TERRAIN INTO THE LWR DESERTS IN THE SRN PART OF THE
STATE. WITH AMPLE MOISTURE ALSO IN PLACE TO FOSTER PROPAGATION ALONG
SWD-MOVING OUTFLOWS...SETUP MAY YIELD A FEW INSTANCES OF DMGG
WIND/HABOOB CONDITIONS...ESPECIALLY THIS EVE THROUGH EARLY TNGT.

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