MESOSCALE PRECIPITATION DISCUSSION 0472
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
315 AM EDT SUN JUL 17 2016
 
AREAS AFFECTED......SOUTHERN MN...NORTHERN AND CENTRAL IOWA...FAR
SOUTHWEST WISCONSIN... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 170715Z - 171215Z
 
SUMMARY...STRENGTHENING MCS EXPECTED TO PEAK BETWEEN 07-09 UTC
THIS MORNING. ADDITIONAL HEAVY RAINS FROM TRAINING AND/OR MERGING
THUNDERSTORMS ARE EXPECTED TO PERSIST THROUGH 12Z. ADDITIONAL
FLASH FLOODING IS LIKELY

DISCUSSION...IR SATELLITE IMAGERY AT 07 UTC THIS MORNING SHOWS
CONTINUED UPSCALE GROWTH WITH THE MCS ACROSS SOUTHERN MN AND
NORTHERN IA...WITH AN EXPANDING AREA OF CLOUD TOPS WITH
TEMPERATURES AT OR BELOW -65C. AT THE SAME TIME...THE LATEST
COMPOSITE RADAR IMAGERY SHOWS A DEVELOPING MCS ACROSS FAR
SOUTHWEST MN AND NORTHWEST IA. THE MCS CONTINUES TO GROW WITHIN A
REGION OF FAVORABLE SYNOPTIC-SCALE UPPER DIFFLUENCE COUPLE WITH
IMPRESSIVE DEEP LAYER MOISTURE AND INSTABILITY. PER THE LATEST SPC
MESOANALYSIS...MUCAPES AROUND 2000 J/KG ARE FEEDING INTO THIS
SYSTEM FROM A ROBUST SOUTHWESTERLY LOW LEVEL JET BETWEEN 40-50
KTS. THE LATEST GPS ANALYSIS INDICATES PRECIPITABLE WATER VALUES
HAVE CLIMBED TO AROUND 1.75 INCHES WITHIN THE MCS.

AS THE LOW-LEVEL JET CONTINUES TO VEER DURING THE EARLY MORNING
HOURS...IT WILL BECOME MORE PARALLEL TO THE MEAN 850-300 MB FLOW.
PER THE LATEST MODEL MBE OR CORFIDI VECTOR FORECAST... THE VEERING
LOW LEVEL JET WILL SLOW DOWN THE SOUTHWARD PROPAGATION OF THE MCS
ACROSS NORTHERN AND CENTRAL IA. THIS WILL ENHANCE THE RISK OF CELL
MERGING AND TRAINING AS THE WESTERN FLANK/BACK EDGE OF THE HEAVIER
PRECIPITATION SHIELD CATCHES UP WITH THE W-E AXIS NORTH OF THE
SURFACE WARM FRONTAL BOUNDARY.

RADAR QUANTITATIVE PRECIPITATION ESTIMATES PER KFSD AND KMPX
WSR-88DS SHOW HOURLY RATES BETWEEN 2-2.5 INCHES WITH MAXIMUM
TOTALS OF 5-6+ INCHES WITHIN THE STRONGEST CONVECTIVE CORES. AMONG
THE HIGH-RESOLUTION CAMS...THE 00Z WRF-AFW SEEMS TO HAVE THE BEST
HANDLE IN TERMS OF THE SOUTHERN EXTENT OF THE HEAVIER RAINFALL
INTO CENTRAL IA...WHILE THE NSSL-WRF IS THE MOST REALISTIC IN
TERMS OF THE UPPER BOUND AMOUNTS (BETWEEN 3-6 INCHES) GIVEN THE
VERIFICATION UP TO THIS POINT. CONSIDERING THE CURRENT 1-3 HOURLY
FFG...THESE TOTALS WILL LEAD TO ADDITIONAL AREAS OF EXCEEDANCE AND
FLASH FLOODING.

ATTN...WFO...ARX...DMX...DVN...FSD...MPX...OAX...

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

LAT...LON   44439423 44219249 43859126 43259067 42529076 
            41859171 41969403 41609551 42029621 42839652 
            43619639 44179586