WPC Met Watch |
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Mesoscale Precipitation Discussion: #0457 (2018) |
(Issued at 245 PM EDT SUN JUL 15 2018
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0457
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT SUN JUL 15 2018
AREAS AFFECTED...SOUTHWEST KY...WESTERN/CENTRAL TN...FAR NORTHEAST
MS...NORTHWEST AL
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 151845Z - 152315Z
SUMMARY...HEAVY SHOWERS AND THUNDERSTORMS LIKELY RESULT IN SOME
AREAS OF FLASH FLOODING THIS AFTERNOON.
DISCUSSION...THE LATEST GOES-16 CLEAN IR SATELLITE IMAGERY SHOWS A
VERY IMPRESSIVE BURST OF DEEP CONVECTION WITH VERY COLD CLOUD TOPS
OVER PORTIONS OF SOUTHWEST KY AND NORTHWEST TN. THE ACTIVITY IS
FOCUSING WITHIN A RATHER CONFLUENT LOW LEVEL FLOW PATTERN AROUND
THE SOUTHEAST FLANK OF AN AREA OF LOW PRESSURE AND WITH PROXIMITY
OF AN OUTFLOW BOUNDARY WHICH WAS GENERATED FROM EARLIER
CONVECTION. THE LATEST RAP ANALYSIS IS SHOWING A VERY UNSTABLE
BOUNDARY LAYER ACROSS SOUTHWEST TN WHERE THERE IS A NOSE OF MLCAPE
VALUES REACHING OVER 3000 J/KG.
GIVEN THE STRONG AXIS OF DIURNAL HEATING ALONG THE SOUTHWEST FLANK
OF THE OUTFLOW BOUNDARY AND TRANSPORT OF VERY MOIST/UNSTABLE AIR
UPSTREAM...THERE WILL LIKELY BE A CONTINUED EXPANSION OF VERY
HEAVY SHOWERS AND THUNDERSTORMS THROUGH THE AFTERNOON HOURS. SOME
OF THIS CONVECTION MAY ADVANCE EAST OVER AREAS THAT WERE IMPACTING
THIS MORNING BY LOCALLY HEAVY RAINFALL. ADDITIONAL AREAS OF
CONVECTION ARE LIKELY TO EVOLVE FARTHER SOUTH DOWN INTO PORTIONS
OF FAR NORTHEAST MS AND NORTHWEST AL AS WELL WHERE THE SAME
OUTFLOW BOUNDARY IMPACTING CENTRAL/WESTERN TN IS FOCUSED NEARBY.
THE PWATS ACROSS THE REGION REMAIN VERY HIGH AND ARE ON THE ORDER
OF 2.25 INCHES WHICH WILL FOSTER HIGHLY EFFICIENT RAINFALL
PROCESSES FOR ENHANCED RAINFALL RATES. EXPECT RATES TO LOCALLY
EXCEED 2.5 INCHES/HR...WITH POTENTIALLY HIGHER RATES WHERE CELL
MERGERS AND OVERSHOOTING TOPS OCCUR THIS AFTERNOON.
THE LATEST HRRR GUIDANCE IS SUPPORTING LOCALLY AS MUCH AS 3 TO 5
INCHES OF RAIN THROUGH LATE-AFTERNOON. THESE TOTALS AND ESPECIALLY
WITH SUCH INTENSE SHORT-TERM RATES WILL LIKELY CAUSE SOME AREAS OF
FLASH FLOODING. WILL CONTINUE TO MONITOR.
ORRISON
ATTN...WFO...BMX...HUN...LMK...MEG...OHX...PAH...
ATTN...RFC...LMRFC...OHRFC...SERFC...
LAT...LON 37158765 36568691 35798676 34908689 34208739
34498822 35548848 35918883 36288919 36988883
Last Updated: 245 PM EDT SUN JUL 15 2018
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