MESOSCALE PRECIPITATION DISCUSSION 0732
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
124 AM EDT SUN OCT 09 2016
 
AREAS AFFECTED...EASTERN VA...EASTERN MD...SOUTHERN DE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 090530Z - 091200Z
 
SUMMARY...HEAVIEST RAINFALL SHIFTING OFF THE COAST IN NEXT FEW
HOURS. MODERATE TO HEAVY SHIELD PRECIP TO CONTINUE ACROSS DELMARVA
THROUGH EARLY MORNING HOURS POSING SOME CONTINUED FLOODING THREAT.

DISCUSSION...GOES-EAST AND NATIONAL RADAR MOSAIC INDICATE A
CONTINUED ELONGATION NORTH TO SOUTH OF MATTHEW DUE TO VERTICAL
SHEARING EFFECTS AND TAKING ON A MORE CLASSIC BAROCLINIC
SHAPE/LOOK.  HEAVIEST RAINFALL CORES WITH RATES OVER 2.5"/HR HAVE
BEEN NEAR INTERSECTION OF STATIONARY FRONT THAT HAS BEEN GENERALLY
PARALLEL TO THE CAROLINA/DELMARVA COAST AND THE STRONG CONVERGENCE
BAND - EFFECTIVE COLD FRONT BETWEEN WARM/UNSTABLE AIR AND S AND
SSWLY DRIER AIR THAT HAS WRAPPED AROUND THE SOUTHERN AND EASTERN
HEMISPHERES OF MATTHEW.  CURRENTLY THIS INTERSECTION IS LOCATED
NEAR VIRGINIA BEACH LIFTING ENE LIKELY TO BE OFFSHORE IN THE NEXT
HOUR OR SO.  ADDITIONALLY FROM RADAR MOSAIC...IT APPEARS
CONVECTIVE INITIATION POINTS ARE DRIFTING EASTWARD SUGGESTING THE
SURFACE FRONT IS ALSO SHIFTING FURTHER OFFSHORE.  AS SUCH EXTREME
RATES OVER 2"/HR ARE LIKELY ENDING EXCEPT FOR EXTREME SE VA AND
MAYBE S TIP OF DELMARVA OVER THE NEXT HOUR OR SO.   

STILL VERY STRONG ISENTROPIC ASCENT FROM THE WARM SECTOR CONTINUES
TO BE STRONG ACROSS THE FRONT WITH MAXIMIZED 700-850MB LAYER
FRONTOGENETIC FORCING FORECAST TO TRACK ACROSS THE SOUTHERN
DELMARVA WITH 1-1.5"/HR RATES LIKELY AND AN ADDITIONAL 2-4"
EXPECTED AS THE REST OF THE SHIELD MIGRATES EASTWARD WITH TIME.

A SECONDARY MAXIMA WITH RATES OF 0.5-1" CAN BE SEEN WITH ENHANCED
REFLECTIVITY ON RADARS ACROSS N HALIFAX TO BUCKINGHAM COUNTIES IN
S CENTRAL VA IS SUPPORTED BY A CONFLUENCE OF MID-LEVEL FORCING
WHILE DIRECTLY BENEATH MAXIMIZE UPPER LEVEL DIVERGENCE AT THE
RIGHT ENTRANCE TO MATTHEW'S OUTFLOW JET.  AS THE JET LIFTS
NORTH-NORTHEAST...THIS MAXIMA WILL ALSO LIFT EASTWARD WITH
CONTINUED DIVERGENCE WHILE RECEIVING MID LEVEL (7-5H MST
CONVERGENCE).  THIS FORCING AND SATURATED PROFILES SUB CLOUD LAYER
COULD PRODUCE AN ADDITIONAL 1-1.5" TOTALS ACROSS THE NECKS OF E VA
ALONG THE CHESAPEAKE BAY AND EVENTUALLY ACROSS SE MD/S DE. 
UPSTREAM 60KT WESTERLY 3H JET IS RAPIDLY ADVANCING ACROSS IL/IN
AND SHOULD HELP PRESS THE FORCING OUT TO SEA THROUGH 14-15Z.  THE
ADDITIONAL RAINFALL THOUGH NOT FAST FALLING WOULD LEAD TO STORM
TOTALS OF 3-5" ACROSS THE AREA POSSIBLY REACHING LONGER TERM
FLOODING THRESHOLDS.       

GALLINA

ATTN...WFO...AKQ...LWX...MHX...PHI...RNK...

ATTN...RFC...MARFC...SERFC...

LAT...LON   39017516 38747484 37977511 37507541 36617567 
            36157570 36257601 36537662 36907755 36927809 
            36667914 37807887 38297723 38537655 38847572