SPC AC 281630

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1130 AM CDT WED OCT 28 2015

   VALID 281630Z - 291200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM PARTS OF THE SOUTHEAST
   INTO THE UPR OH VLY/MID-ATLANTIC/NEW ENGLAND...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER A SMALL PARTS OF THE LWR
   MS VLY...

   ...SUMMARY...
   ISOLATED DAMAGING WINDS AND A TORNADO OR TWO MAY OCCUR FROM THE
   CAROLINAS INTO PARTS OF THE NORTHEAST THIS AFTERNOON AND TONIGHT.
   ISOLATED STORMS WITH HAIL MAY OCCUR OVER THE LOWER MISSISSIPPI
   VALLEY.

   ...SYNOPTIC SETUP...
   BROAD CNTRL/ERN U.S. LOW/TROUGH EXPECTED TO STRENGTHEN AS CENTER OF
   CIRCULATION TRACKS ESE FROM ND TO SE MN BY EVE...AND THEN TURNS ENE
   TO LK HURON TNGT/EARLY THU. AT THE SAME TIME...POTENT SHORTWAVE
   IMPULSE NOW ENTERING AR SHOULD MOVE RAPIDLY E TO THE SRN
   APPALACHIANS THIS EVE...BEFORE CONTINUING NE OFF THE MID-ATLANTIC
   CST EARLY THU.

   SFC PATTERN WILL REMAIN COMPLEX...WITH CYCLONIC FLOW PREVAILING AT
   LOW LVLS OVER THE ERN THIRD OF THE COUNTRY ON BACKSIDE OF RETREATING
   SFC RIDGE NOW EXITING NEW ENGLAND. FRAGMENTED...SHALLOW WARM FRONT
   WILL MOVE/DEVELOP GENERALLY NWD ACROSS THE MID-ATLANTIC TODAY...AND
   INTO NY/NEW ENGLAND TNGT...WHILE MAIN COLD FRONT ASSOCIATED WITH UPR
   MS VLY TROUGH ADVANCES E/SE ACROSS THE OH VLY/OZARKS/SRN PLNS. AHEAD
   OF THIS FRONT...A WEAKER FRONT/WIND SHIFT WILL PRECEDE THE AR UPR
   IMPULSE ACROSS THE TN VLY. ANOTHER CONFLUENCE AXIS...NOW ANALYZED
   FROM ERN OH SSW INTO SW VA...SHOULD PROGRESS MORE SLOWLY EWD THROUGH
   THIS AFTN.

   ...ERN/SERN/MID-ATLANTIC STATES TODAY THROUGH EARLY TNGT...
   AMPLE MOISTURE AND LOW-LVL SHEAR WILL BE PRESENT ACROSS A LARGE PART
   OF THE E CNTRL U.S. THIS AFTN AND EVE TO POSE AT LEAST A CONDITIONAL
   RISK FOR LOCALLY SVR STORMS WITHIN BROAD REGIME OF LOW-LVL CYCLONIC
   FLOW. THIS POTENTIAL APPEARS GREATEST OVER /1/ PARTS OF THE UPR OH
   VLY AND ALONG THE WRN SLOPES OF THE APPALACHIANS...AND /2/ OVER
   PARTS OF THE SOUTHEAST AND MID-ATLANTIC.

   MODEST SFC HEATING AND PERSISTENT LOW-LVL UPLIFT ALONG UPR OH VLY
   CONFLUENCE ZONE MAY SUPPORT SCTD AFTN SHOWERS/ISOLD STORMS IN
   ENVIRONMENT OF VERY STRONG LOW-LVL SHEAR/FLOW FROM WV NNE INTO FAR
   ERN OH/WRN PA...WHERE PW WILL BE AROUND 1.25 INCHES. SOME DEGREE OF
   UPR-LVL SUPPORT ALSO MAY BE PROVIDED BY DEAMPLIFYING UPR IMPULSE NOW
   MOVING NNE ACROSS OH/LWR MI. LOW TO MID-LVL LAPSE RATES
   WILL...HOWEVER...REMAIN VERY WEAK...AND A SHALLOW STABLE LAYER
   LIKELY WILL LINGER OVER MOST AREAS AT THE SFC. THUS...AN UPGRADE TO
   SLIGHT RISK DOES NOT APPEAR WARRANTED ATTM. THE SVR THREATS WOULD BE
   LIMITED TO A BRIEF TORNADO AND/OR LOCALLY DMGG WIND.

   FARTHER S/SE...MORE SUBSTANTIAL MOISTURE /PW AOA 1.50 INCHES WITH
   DEWPOINTS WELL INTO THE 60S F/ WILL PREVAIL FROM THE CAROLINAS NEWD
   INTO SE PA/NJ...ALONG AND S OF SLOWLY ADVANCING WARM FRONTAL
   SEGMENTS. WINDS WILL GRADUALLY DIMINISH WITH TIME AND SRN
   EXTENT...BUT WILL REMAIN SUFFICIENT FOR ORGANIZED/SUSTAINED STORMS.
   AND...AMPLE LOW-LVL DIRECTIONAL SHEAR WILL EXIST NEAR SHALLOW WARM
   FRONT TO SUPPORT LOW-LVL MESOS AND A RISK FOR TORNADOES. SATELLITE
   AND MORNING RAOB DATA SUGGEST...HOWEVER...THAT MOST OF THE REGION SW
   OF ABOUT RALEIGH NC WILL BE IN A ZONE OF RELATIVE NVA THROUGH THE
   DAY...ALTHOUGH LIMITED DCVA WILL LINGER FARTHER N AND E INTO THE
   CHESAPEAKE BAY REGION/SE PA-NJ. AT THE SAME TIME...MID-LVL LAPSE
   RATES WILL BE WEAK...WITH FURTHER 500 MB WARMING EXPECTED ACROSS
   MUCH OF THE CAROLINAS AND VA. THE OVERALL SET-UP APPEARS TO BE ONE
   WITH A FAIRLY EXPANSIVE BUT LOW-CONDITIONAL THREAT FOR BRIEF
   TORNADOES. THIS THREAT DOES NOT APPEAR TO BE OF SUFFICIENT MAGNITUDE
   OR FOCUS...HOWEVER...TO WARRANT AN UPGRADE OF SLIGHT RISK ATTM.

   ...ERN PA/SE NY INTO PARTS OF SRN NEW ENGLAND OVERNIGHT...
   LOW-LVL MOISTENING/MODEST DESTABILIZATION WILL CONTINUE OVER THIS
   REGION THROUGH TNGT/EARLY THU AHEAD OF APPROACHING COLD FRONT. LOW
   TO MID-LVL LAPSE RATES WILL...HOWEVER...REMAIN AOB 6.5 C/KM. 
   NEVERTHELESS...SBCAPE OF 100-250 J/KG...COUPLED WITH GLANCING
   INFLUENCE OF SRN SHORTWAVE IMPULSE...MAY BE SUFFICIENT FOR A BAND OF
   LOW-TOPPED CONVECTION ALONG THE BOUNDARY. ALTHOUGH LOW-LVL FLOW WILL
   SOMEWHAT VEER AND DIMINISH WITH THE APPROACH OF THE IMPULSE...IT
   SHOULD REMAIN SUFFICIENT TO POSE AT LEAST A CONDITIONAL RISK FOR
   LOCALLY DMGG GUSTS.

   ...SRN/ERN AR INTO NRN MS THIS AFTN/EVE...
   APPRECIABLE FORCING FOR ASCENT WILL OVERSPREAD PARTS OF AR AND NRN
   MS LATER TODAY AS UPSTREAM UPR IMPULSE CONTINUES EWD. SATELLITE
   SUGGESTS THAT MODERATE SFC HEATING WILL OCCUR OVER REGION THIS AFTN
   ONCE BOUNDARY LAYER STRATUS MIXES OUT...AND SATELLITE/SFC DATA SHOW
   AMPLE MOISTURE IN PLACE /PW CLOSE TO 1 INCH AND SFC DEWPOINTS AROUND
   60 F/ FOR ROBUST UPDRAFTS. WITH 500 MB TEMPS AROUND MINUS 14C AND
   40-50 KT UNIDIRECTIONAL...WLY CLOUD-LYR SHEAR...SETUP COULD SUPPORT
   A BAND OR TWO OF LOW-TOPPED STORMS CAPABLE OF MARGINAL HAIL THROUGH
   ABOUT SUNSET.

   ..CORFIDI/LEITMAN.. 10/28/2015

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