MESO: Mesoscale Discussion 1952

ACUS11 KWNS 090727
SWOMCD
SPC MCD 090727
NCZ000-091000-

MESOSCALE DISCUSSION 1952
NWS STORM PREDICTION CENTER NORMAN OK
0227 AM CDT SUN SEP 09 2007

AREAS AFFECTED...PORTIONS EXTREME ERN NC...PRIMARILY OUTER BANKS FOR
T.S. GABRIELLE TORNADO POTENTIAL.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 090727Z - 091000Z

BRIEF/SMALL TORNADO CANNOT BE RULED OUT FROM ANY SUPERCELLS THAT MAY
DEVELOP WITHIN SPIRAL CONVERGENCE/CONVECTIVE BANDS...MAINLY NE OF
CENTER. LATEST NHC FCST TRACK...PER ADVISORIES UNDER WMO HEADER
WTNT22 KNHC...SUGGESTS MOST FAVORABLE SECTOR OF SYSTEM WILL AFFECT
MAINLY OUTER BANKS...FROM INNER CORE REGION OF CYCLONE OUTWARD
NNEWD-NEWD. BECAUSE OF MRGL NATURE OF RISK AND ITS VERY LIMITED
SPATIAL EXTENT OVER LAND...WW IS NOT ANTICIPATED ATTM.

SFC MESOANALYSIS SHOWS FRONTAL ZONE -- DISTINGUISHING
TROPICAL/MARINE AIR WITH 70S TEMPS/DEW POINTS FROM COOLER/DRIER
INLAND AIR MASS...FROM ERN ALBEMARLE SOUND SSWWD ACROSS PAMLICO
SOUND TO ABOUT 20 SSE NKT THEN SSWWD OVER ATLANTIC WATERS OFFSHORE
ILM. OFFSHORE SFC TROUGH EXTENDS NEWD FROM TS CENTER. FRONT MAY
DRIFT WWD ACROSS INLAND PORTIONS DARE/HYDE AND PAMLICO COUNTIES
BEFORE PASSAGE OF TS CENTER. THROUGH REMAINDER PRE-DAWN
HOURS...MOST FAVORABLE INSTABILITY SHOULD BE CONFINED TO AREAS ALONG
OUTER BANKS -- ALONG AND E OF BAROCLINIC GRADIENT -- WHERE MRGLLY
BUOYANT MARINE AIR FROM ATLANTIC IS N PLACE. MODIFIED RAOBS AND RUC
THERMODYNAMIC SOUNDINGS -- LATTER TYPICALLY BEING MORE
REPRESENTATIVE IN TROPICAL SITUATIONS THAN RUC WIND PROFILES --
INDICATE MLCAPE INCREASING FROM AROUND 500 J/KG OVER ERN PAMLICO
SOUND TO OVER 1500 J/KG OFFSHORE. ACTUAL BUOYANCY SHOULD CORRESPOND
QUITE CLOSELY TO SFC THETAE VALUES...GIVEN NEARLY MOIST-ADIABATIC
LAPSE RATES THROUGH DEEP LAYER ALOFT AND LACK OF SIGNIFICANT
STABLE/CAPPING LAYERS EXPECTED IN THIS REGIME.

KINEMATIC PROFILE IS MORE UNCERTAIN BECAUSE OF LACK OF OBSERVATIONAL
SAMPLING...WITH 6Z MHX RAOB MISSING WIND DATA AND MHX VWP LOCATED
LEFTWARD OF FCST STORM TRACK IN LESS FAVORABLE KINEMATIC SECTOR.
ALSO...RUC-BASED OBJECTIVE ANALYSIS FIELDS OF WIND-BASED PARAMETERS
LIKELY DO NOT REPRESENT THIS SYSTEM WELL -- ESPECIALLY WITH INWARD
EXTENT TOWARD CENTER -- BECAUSE OF THAT MODEL'S POOR RESOLUTION OF
TIGHT/TROPICAL PRESSURE/WIND GRADIENTS. STILL...PRIND SMALL AREA OF
NERN QUADRANT ALONG AND E OF FRONT AND W OF SFC TROUGH SHOULD
SUSTAIN RELATIVELY BACKED SFC WINDS. THIS REGIME MAY YIELD ENOUGH
LOW LEVEL SRH TO SUPPORT ROTATION FOR ANY SUSTAINED/DISCRETE CELLS
THAT DEVELOP AND MOVE DEVIANTLY NWWD -- RIGHTWARD OF MEAN FLOW
VECTOR.

.EDWARDS.. 09/09/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MHX...

34667664 34947640 35407612 35687572 35837552 35677545
35427547 35207551 35217561 35117590 34967611 34537650
34667659

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write chris@lib.siu.edu.