DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161957
SWODY1
SPC AC 161955

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT SAT MAR 16 2013

VALID 162000Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

...ERN KY/TN...WV...VA...NRN NC...
LATEST SURFACE OBSERVATIONS SHOW DEWPOINTS IN THE 40S F ACROSS THE
REGION WHICH IS RESULTING IN ONLY WEAK INSTABILITY. ISOLATED CELLS
HAVE FORMED OVER WV...AND ADDITIONAL ACTIVITY MAY EVENTUALLY
MATERIALIZE WITH ADDITIONAL HEATING. WITH STEEPENING LOW LEVEL LAPSE
RATES...AND STRONG WLY FLOW ALOFT...LOCALLY GUSTY WINDS MAY OCCUR.
COOL TEMPERATURE PROFILES ALOFT AND FAVORABLE DEEP LAYER SHEAR MAY
ALSO YIELD A FEW LONGER LIVED CELLS CAPABLE OF HAIL...BUT THE
OVERALL SEVERE COVERAGE SHOULD REMAIN ISOLATED DUE TO DOWNSLOPE AND
MARGINAL MOISTURE.

FOR MORE INFORMATION...SEE MESOSCALE DISCUSSION 270.

..JEWELL.. 03/16/2013

.PREV DISCUSSION... /ISSUED 1115 AM CDT SAT MAR 16 2013/

...VA/NC INTO SERN KY/TN...
WNWLY FLOW ALOFT ACROSS MUCH OF THE CENTRAL/ERN US IS FORECAST TO
GRADUALLY BECOME MORE ZONAL AS A SERIES OF SHORT WAVE TROUGHS
PROGRESS ACROSS THE GREAT LAKES AND NERN STATES. AT THE SURFACE...A
LOW OVER OH WILL MOVE/REDEVELOP EWD ACROSS THE APPALACHIANS INTO VA
THIS AFTERNOON BEFORE CONTINUING OFFSHORE TONIGHT. A COLD FRONT
TRAILING WSWWD FROM THE LOW WILL MOVE SLOWLY SEWD EXTENDING FROM VA
INTO SERN KY AND NWRN TN BY EVENING...AND ACROSS NC AND TN LATER
TONIGHT.

LIMITED MOISTURE CONTINUES TO ACCOMPANY THIS SYSTEM ACROSS THE OH
VALLEY INTO THE MID ATLANTIC STATES...WITH OBSERVATIONAL DATA FROM
RAOBS AND SATELLITE SOURCES INDICATING PRECIPITABLE WATER VALUES OF
0.75-0.85 INCH...WITH SURFACE DEW POINTS IN THE 40S. HOWEVER...A
PLUME OF STEEPER MID LEVEL LAPSE RATES EXTENDS EWD ACROSS THE OH AND
TN VALLEYS INTO THE MID ATLANTIC REGION WHICH IS EXPECTED TO AID IN
THE DEVELOPMENT OF MARGINAL INSTABILITY /MUCAPE OF 300-700 J PER KG/
THIS AFTERNOON. VISIBLE SATELLITE IMAGERY SHOWS DIMINISHING CLOUDS
FROM SRN WV INTO CENTRAL/SRN VA AND NWRN NC WHERE STRONGER DIABATIC
HEATING IS EXPECTED...CONTRIBUTING TO DEVELOPMENT OF WELL-MIXED
PBL/LOW LEVEL INVERTED-V SOUNDING STRUCTURE/ AS INDICATED BY RAP/NAM
FORECAST SOUNDINGS.

SOME CONVECTION-ALLOWING MODELS INDICATE MULTIPLE CONVECTIVE BANDS
DEVELOPING THIS AFTERNOON AND SPREADING SEWD THROUGH THE EVENING
HOURS. DESPITE LIMITED INSTABILITY...STRONG WINDS ALOFT AND
ASSOCIATED VERTICAL SHEAR MAY AID IN STORM ORGANIZATION. STEEPER
MID LEVEL LAPSE RATES COUPLED WITH A WELL MIXED DEEPER PBL SUGGEST
POTENTIAL FOR ISOLATED STORMS TO PRODUCE GUSTY WINDS AND POSSIBLY
MARGINAL HAIL...BUT OVERALL SEVERE THREAT WILL BE LIMITED BY WEAK
INSTABILITY.

...NRN OK/SRN KS EWD INTO THE OZARKS...
A STRENGTHENING SWLY NOCTURNAL LOW LEVEL JET IS FORECAST TO DEVELOP
THIS EVENING FROM OVER SRN PLAINS...RESULTING IN FOCUSED LOW LEVEL
THERMAL/MOISTURE ADVECTION AND CONVERGENCE ALONG AND NORTH OF A
FRONT EXTENDING FROM NRN AR INTO SWRN OK. MODEL FORECAST SOUNDINGS
SHOW DEVELOPMENT OF ELEVATED INSTABILITY GENERALLY BASED IN THE
850-700 MB LAYER WITH MAXIMUM CAPE AOB 1000 J/KG. WIDELY SCATTERED
THUNDERSTORMS ARE EXPECTED TO DEVELOP AFTER 03-06Z OVER THE AREA AND
SPREAD EWD THROUGH THE OVERNIGHT HOURS. ALTHOUGH A STORM OR TWO MAY
BE CAPABLE OF PRODUCING SMALL HAIL...POTENTIAL APPEARS TOO
LOW/CONDITIONAL TO ASSIGN AOA 5 PERCENT PROBABILITY AREA ATTM.

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