WPC Met Watch |
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Mesoscale Precipitation Discussion: #0620 (2016) |
(Issued at 751 PM EDT MON AUG 29 2016
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0620
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
751 PM EDT MON AUG 29 2016
AREAS AFFECTED...EAST CENTRAL MN INTO NORTHERN WI
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 292350Z - 300350Z
SUMMARY...CONVECTION TRAINING IN A HIGH MOISTURE CONTENT AIRMASS
AHEAD OF A COLD FRONT COULD PRODUCE FLASH FLOODING THROUGH THE
EVENING HOURS.
DISCUSSION...CONVECTION HAS FLARED ACROSS EAST CENTRAL MN INTO
NORTHERN WI...AS SHALLOW CIN HAS BEEN ERASED...AND INSTABILITY HAS
JUMPED TO NEAR 3000 J/KG OF MLCAPE. THIS COINCIDES WITH A RIBBON
OF 1.50 TO 1.75 INCH PRECIPITABLE WATER AIR ACROSS THE SAME AXIS.
IN THIS MOIST AIRMASS...THE KMPX RADAR HAS SHOWN HOURLY RAINFALL
RATES NEAR 2.25 INCHES ACROSS KANABEC COUNTY MN.
THE IR LOOP HAS SHOWN STEADILY COOLING CLOUD TOPS AHEAD OF A SHORT
WAVE MOVING EASTWARD OVER ND. THE LATEST RAP SHOWS DIVERGENCE
INCREASING AHEAD OF THE SHORT WAVE (WHICH HAS BEEN SLOWER IN THE
MODEL THAN IN REALITY)...AND THE SYNOPTIC SCALE ASCENT SHOULD
SUPPORT CONVECTION THROUGH AT LEAST 0330Z ACROSS PORTIONS OF EAST
CENTRAL MN INTO NORTHERN WI.
THE LATEST RAP ALSO SHOWS THAT MOISTURE AND INSTABILITY PROFILES
REMAIN ABOUT THE SAME INTO THE LATE EVENING HOURS. WHILE THE MID
LEVEL FLOW SHOULD CONTINUE A RELATIVELY STEADY EASTWARD MOVEMENT
OF THE INDIVIDUAL CELLS ALONG THE LINE...CORFIDI VECTORS SLOW TO
THE POINT THAT TRAINING AND BACKBUILDING ARE EXPECTED. THIS WOULD
INCREASE THE POTENTIAL FOR FLASH FLOODING AHEAD OF THE COLD FRONT.
THE LATEST HRRR RUNS ACROSS THIS AREA HAVE INDICATED LOCAL 2-4
INCH RAINFALL TOTALS ACROSS EAST CENTRAL MN AND NEARBY NORTHWEST
WI (THOUGH THE HRRR HAS BEEN CONSISTENTLY 2 OR 3 HOURS SLOWER THAN
REALITY WITH THE CONVECTION). ONE AND THREE HOUR FLASH FLOOD
GUIDANCE VALUES HERE ARE AS LOW AS 1.50 INCHES...AND TRAINING OR
BACKBUILDING AHEAD OF THE FRONT COULD CERTAINLY PRODUCE RAINFALL
RATES NEAR 1.50 INCHES.
HAYES
ATTN...WFO...DLH...GRB...MPX...
ATTN...RFC...NCRFC...
LAT...LON 46489246 46238973 45548907 45469212 45109373
45659424
Last Updated: 751 PM EDT MON AUG 29 2016
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