MESOSCALE PRECIPITATION DISCUSSION 0424
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
901 PM EDT TUE JUL 05 2016
 
AREAS AFFECTED...S MINNESOTA...SW WISCONSIN...N IOWA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 060100Z - 060600Z
 
SUMMARY...MATURING MCS INCREASING IN RAINFALL EFFICIENCY MAY POSE
INCREASING THREAT OF LOCALIZED FLASH FLOODING CONDITIONS WITH RAIN
RATES OF 2-2.5"/HR

DISCUSSION...RADAR MOSAIC INDICATES CONSOLIDATING  SQUALL LINE
WITH TWO EMBEDDED MESO-LOWS JUST EAST AND SW OF THE TWIN CITIES. 
WITH THE PRESSURE FALLS DUE TO THE APPROACH OF THE SQUALL
LINE...LOW LEVEL INFLOW HAS VEERED TO SW ON THE WESTERN FLANK AND
BACKED TO SE ON THE EASTERN FLANK WITH LOW 70 TDS AND TPWS AOA
1.75" AND AS FLOW IS GENERALLY ORIENTED PERPENDIUCLAR TO THE
LINE...RESULTING IN STRONG FLUX SUPPORTING INCREASINGLY EFFICIENT
RAINFALL PRODUCTION.   NWS MESONET AND BACKYARD WEATHER STATIONS
SUPPORT RATES OF 2-3"/HR OR GREATER WITHIN THE LINE AND THOUGH
LINE IS MOVING AT A STEADY PACE...IT HAS BEEN RESULTING IN TOTALS
IN THE 2" RANGE WHICH IS APPROACHING 1HR FFG VALUES IN THE AREA.

AS NIGHT FALLS...THE SQUALL WILL CONTINUE TO BOW OUT ACROSS SE
MN/SW WI WITH SIMILAR RAINFALL EFFICIENCY.  HOWEVER...THE WESTERN
FLANK WILL BE PROGRESS A BIT SLOWER AND ORIENT NW-SE ALONG WITH
STRENGTHENING SWLY LLJ WILL SUPPORT CONTINUED STRONG ORTHOGONAL
MST CONVERGENCE/UPGLIDE ASCENT FOR SOME CELL TRAINING AND
PERSISTENT REDEVELOPMENT ON THE UPWIND EDGE RESULTING IN HIGHER FF
THREAT OVER NE IOWA BY 04-05Z.  HI-RES GUIDANCE CONTINUES TO
WAFFLE ON THE EXACT STRENGTH/OREINTATION AND PERSISTENCE OF THE
NW-SE LINE FOR HIGHER CONFIDNECE IN EXACT EVOLUTION AT THIS TIME. 
HOWEVER...RECENT V.2 HRRR RUNS SUGGEST SOME ADDITIONAL FORCING
FROM WAVE PRODUCING CONVECTION ACROSS E NEB MAY BE THE DRIVING
FACTOR TOWARD A LARGER SCOPE OF FLASH FLOODING CONDITIONS ACROSS N
CENTRAL/NE IOWA AFTER 06Z.   

GALLINA

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

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

LAT...LON   45359228 44759120 44009034 42928938 42139128 
            42279267 42629349 43109409 43239422 43779483 
            44149504 44439463 44559401