Thursday, April 19, 2012

MESO: Mesoscale Discussion 0566

ACUS11 KWNS 191924
SWOMCD
SPC MCD 191923
IAZ000-NEZ000-192100-

MESOSCALE DISCUSSION 0566
NWS STORM PREDICTION CENTER NORMAN OK
0223 PM CDT THU APR 19 2012

AREAS AFFECTED...CNTRL/W-CNTRL IA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 191923Z - 192100Z

SOME INTENSIFICATION OF ONGOING CONVECTION IN FAR ERN NEB MAY OCCUR
INTO W-CNTRL/CNTRL IA THIS AFTERNOON...WHICH MAY POSE AN
ISOLATED/MARGINAL SVR THREAT. THE ISSUANCE OF A WW IS UNLIKELY.

OMAHA NEB WSR-88D DATA INDICATE INTENSIFYING ELEVATED CONVECTION TO
THE N/W OF THE OMAHA AREA. THIS ACTIVITY IS IN ASSOCIATION WITH A
SEGMENT OF THE WARM CONVEYOR BELT THAT WRAPS AROUND THE NWRN
SEMICIRCLE OF AN INCREASINGLY BETTER-DEFINED EXTRATROPICAL CYCLONE
CROSSING THE MIDDLE MISSOURI VALLEY REGION PER WATER VAPOR IMAGERY.
BETWEEN 35 AND 60 KT OF SWLY/WSWLY FLOW WITHIN THE 3-7-KM-AGL LAYER
PER OMAHA NEB AND DES MOINES IA VWP DATA SUGGESTS THAT THIS
CONVECTION WILL QUICKLY MOVE NEWD/ENEWD INTO W-CNTRL/CNTRL IA DURING
THE NEXT FEW HOURS. AS THE LOW-LEVEL STATIC STABILITY DECREASES TO
THE SOUTH OF A STATIONARY FRONT EXTENDING EAST FROM A SFC LOW NEAR
OMAHA OWING TO INSOLATION/DIABATIC HEATING WITHIN THE DRY-SLOT
CORRIDOR OF THE CYCLONE...THE AFOREMENTIONED CONVECTION WILL LIKELY
ENCOUNTER INCREASING ELEVATED INSTABILITY NORTH OF THE STATIONARY
FRONT AS THE LESS-STATICALLY-STABLE AIR IS ADVECTED ATOP THE
NEAR-SFC COLD DOME. ADDITIONAL CONVECTION MAY ALSO DEVELOP NORTH OF
THE STATIONARY FRONT AS PARCELS ORIGINATING FROM THE WARM SECTOR
REACH THEIR LFC/S NORTH OF THE BOUNDARY. THE PRIMARY CONCERN WITH
ALL OF THIS ACTIVITY WILL BE HAIL...PERHAPS APPROACHING MARGINALLY
SVR THRESHOLDS GIVEN SUFFICIENTLY STRONG DEEP-LAYER SHEAR AND MUCAPE
NORTH OF THE BOUNDARY. HOWEVER...IF ANY STORMS ATTAIN MID-LEVEL
MESOCYCLONES AND EXHIBIT DEVIANT MOTION TO THE RIGHT OF THE MEAN
FLOW...THEY MAY INTERACT WITH THE SFC BOUNDARY/LOW WHILE INGESTING
SFC-BASED INFLOW...IN WHICH CASE A THREAT FOR A WEAK/BRIEF TORNADO
CANNOT BE RULED OUT PROVIDED THE LOW-LEVEL HODOGRAPH CURVATURE PER
DES MOINES IA VWP DATA AND BACKGROUND VERTICAL VORTICITY NEAR THE
FRONT/LOW.

..COHEN.. 04/19/2012

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

ATTN...WFO...DMX...FSD...OAX...

LAT...LON 41569503 41319565 41519606 41839609 42209582 42529447
42429331 41929302 41809344 41649421 41569503

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