MESOSCALE PRECIPITATION DISCUSSION 0162
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
935 PM EDT THU MAY 17 2018

AREAS AFFECTED...LOWER OH VALLEY...LOWER/MID MS VALLEY...MID SOUTH

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 180130Z - 180600Z

SUMMARY...SEVERAL CLUSTERS OF HEAVY SHOWERS AND THUNDERSTORMS WILL
TEND TO LINGER THROUGH THE LATE EVENING HOURS. GIVEN EARLIER
RAINS...SOME FLASH FLOODING WILL REMAIN POSSIBLE.

DISCUSSION...A CONSENSUS OF THE LATEST HRRR GUIDANCE AND THE
OVERALL HIRES CAM CONSENSUS SUPPORTS THE IDEA OF CONVECTION
TENDING TO LINGER A BIT ACROSS AREAS OF THE LOWER OH
VALLEY...MID/LOWER MS VALLEY AND PORTIONS OF THE MID SOUTH OVER
THE NEXT SEVERAL HOURS.

ONGOING CONVECTION ACROSS THE REGION IS CHARACTERIZED BY MULTIPLE
BROKEN BANDS OF HEAVY SHOWERS AND THUNDERSTORMS THAT ARE ROTATING
WESTWARD AROUND THE NORTH SIDE OF A BROAD UPPER LOW. EMBEDDED
WITHIN THE LARGE SCALE CIRCULATION ARE A COUPLE OF WELL-DEFINED
VORT CENTERS AND ASSOCIATED PV ANOMALIES. ONE IS OVER CENTRAL MO
AND ANOTHER ONE OVER NORTHERN MS. THIS ENERGY IS PROVIDING AT
LEAST MODEST LARGE SCALE ASCENT OVER THE REGION AND IS INTERACTING
WITH AN ANOMALOUSLY MOIST AND AT LEAST MODESTLY UNSTABLE BOUNDARY
LAYER FOR SUSTAINABLE CONVECTION.

OVER THE NEXT FEW HOURS THE CONVECTIVE COVERAGE SHOULD DECREASE
SOME AS DIURNALLY DRIVEN INSTABILITY IS EXHAUSTED...BUT THE
CYCLONIC FLOW ALOFT AND AFOREMENTIONED VORT ENERGY SHOULD TEND TO
FAVOR SOME BROKEN BANDS OF CONVECTION PERSISTING AND POSSIBLY
REDEVELOPING CLOSE TO THE VORT CENTERS WHERE FORCING IS STRONGEST.
THIS ACTIVITY WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL
AMOUNTS AND ESPECIALLY WITH SOME CELLS VERY SLOW MOVING. THE
RAINFALL RATES ARE LIKELY TO EXCEED 2 INCHES/HR WITHIN THE
STRONGER CONVECTIVE CORES.

EXPECT AS MUCH AS 3 TO 4 INCHES OF RAIN AT LEAST LOCALLY. GIVEN
THE RELATIVELY WET SOIL CONDITIONS...THESE ADDITIONAL AMOUNTS WILL
RESULT IN SOME POTENTIAL FOR FLASH FLOODING.

ORRISON

ATTN...WFO...BMX...HUN...ILX...JAN...LMK...LSX...MEG...OHX...
PAH...SGF...

ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...SERFC...

LAT...LON   38979003 38728873 38068749 36698697 34918700
            33778778 33448875 33748957 34999006 36199067
            36769125 37439179 37919198 38509169 38949089