MESOSCALE PRECIPITATION DISCUSSION 0474
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 AM EDT MON JUL 18 2016
 
AREAS AFFECTED......SOUTHWEST AND SOUTH-CENTRAL IA...FAR NORTHWEST
MO...AND FAR EASTERN NE... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 180650Z - 181150Z
 
SUMMARY...CONVECTION WILL CONTINUE TO GROW UPSCALE AND TRAIN ALONG
AN AXIS OF STRENGTHENING SW LOW LEVEL INFLOW...STRONG AVAILABLE
DEEP LAYER INSTABILITY...AND HIGH PRECIPITABLE WATER AVAILABILITY.

DISCUSSION...AN UPPER LEVEL JET STREAK SLIDING ESE ACROSS THE
UPPER MIDWEST AND UPPER GREAT LAKES REGION IS INDUCING AN UPTICK
IN RIGHT-ENTRANCE REGION UPPER DIVERGENCE ACROSS EASTERN NE AND
SOUTHWEST IA EARLY THIS MORNING. CONVECTION CONTINUES TO BLOSSOM
INTO AN MCS AS A RESULT OF THE DYNAMICAL SUPPORT ALONG WITH A
HIGHLY FAVORABLE THERMODYNAMIC ENVIRONMENT. DEEP-LAYER INSTABILITY
FEEDING INTO THIS DEVELOPING MCS WERE QUITE ROBUST...WITH MUCAPES
BETWEEN 2000-3000 J/KG...WHILE SW LOW LEVEL INFLOW HAS INCREASED
TO AROUND 30 KTS INTO THE QUASI-STATIONARY LOW LEVEL BOUNDARY
ACROSS SOUTHEAST NE AND SOUTHWEST IA. PRECIPITABLE WATER VALUES
PER THE LATEST GPS ANALYSIS WERE BETWEEN AROUND 1.75 INCHES.  

THROUGH 12Z...WHILE THE MEAN CELL MOTIONS ARE EXPECTED TO REMAIN
WESTERLY...A SLOW SE PROPAGATION OF THE MCS IS EXPECTED PER THE
CURRENT SPC MESOANALYSIS ALONG WITH THE LATEST RAP FORECAST
CORFIDI/MBE VECTORS. THIS WILL ALLOW FOR CONTINUED MERGING AND
TRAINING OF CONVECTION FOR THE NEXT SEVERAL HOURS AS THE DYNAMICAL
FORCING WITHIN THE RIGHT ENTRANCE REGION OF THE UPPER JET MAX
CONTINUES. GIVEN THE ROBUST DEEP-LAYER INSTABILITY AND RICH
MOISTURE AVAILABILITY DURING THIS PERIOD...HOURLY RAINFALL RATES
OF 2 TO 2.5+ INCHES ARE EXPECTED WITHIN AREAS OF CELL
MERGING/TRAINING...PARTICULARLY ACROSS FAR SOUTHWEST IA THROUGH
09Z. 

IN TERMS OF THE LATEST MESOSCALE CAM GUIDANCE...THE 05Z PARALLEL
HRRR SEEMS TO HAVE THE BEST HANDLE ON THE HEAVY RAINFALL TRENDS
WITH THE SWATH OF HEAVIEST RAINFALL (BETWEEN 3-6+ INCHES) NOTED
FROM FAR EAST-CENTRAL NE SOUTHEAST THROUGH SOUTHWEST IA AND FAR
NORTHWEST MO THROUGH AROUND 09Z (OR BEFORE THE MCS REACHES ITS
PEAK INTENSITY). THE CAMS ALSO SHOW ISOLATED POCKETS OF 7+ INCHES.

ATTN...WFO...DMX...EAX...OAX...

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   42179615 42119483 41779373 41489313 40849260 
            40439311 40249415 40419502 41239582 41859709