MESOSCALE PRECIPITATION DISCUSSION 0034
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
104 PM EDT TUE MAY 07 2013
 
AREAS AFFECTED...SOUTHEAST WV...SOUTHWEST VA...EXTREME NORTHWEST
NC 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 071703Z - 072303Z
 
SUMMARY...INCREASING THREAT FOR FLASH FLOODING THROUGH THE
AFTERNOON AS ONGOING CONVECTION SHOULD BE SUSTAINABLE AND MAY
INCREASE IN COVERAGE AND ORGANIZATION.

DISCUSSION...LATEST VIS SATELLITE IMAGERY SHOWS INCREASINGLY
WELL-DEFINED CLOUD STREETS OVER SERN VA AS THIS REGION HAS CLEARED
OUT AND IS BECOMING INCREASINGLY UNSTABLE THROUGH AN INCREASE IN
DIURNAL HEATING. FACILITATING THE INCREASE IN SFC-BASED
INSTABILITY IS A NARROW PLUME OF HIGHER DEWPOINTS INVOF A FRONT
WHICH ARE GENERALLY IN THE LOW 60S ATTM. THE INCREASING MOIST AND
UNSTABLE LOW LEVELS WILL BE ADVECTED WEST THROUGH THE AFTERNOON
AROUND A DEEP AREA OF LOW PRESSURE FOCUSED SOUTH OF ROA. MORE
NOTABLE IS THAT THESE STRONGER THERMODYNAMICS WILL BE ADVANCING
INTO AN AREA OF ALREADY RATHER STRONG LOW LEVEL CONVERGENCE...AND
SHOULD HELP TO SUSTAIN OR ENHANCE THE COVERAGE OF ONGOING
CONVECTION DESPITE ITS ELEVATED NATURE OVER SOUTHWEST VA AND
SOUTHEAST WV. GIVEN EXPECTED RAINFALL RATES OF 1 INCH/HR OVER
SATURATED SOIL...AND THE EXPECTATION OF REPEATING AND POTENTIAL
TRAINING OF CONVECTIVE CELLS...THE THREAT FOR FLASH FLOODING
SHOULD INCREASE AND ESPECIALLY OVER HIGHER TERRAIN WHERE
OROGRAPHICS WILL HELP TO ENHANCE THE RAINFALL RATES.

ORRISON


ATTN...WFO...LWX...RNK...RLX...

LAT...LON   37647853 36937907 36408001 36278070 36338141 36858154
            37438148 38088102 38558017 38547903 37647853