WPC Met Watch |
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Mesoscale Precipitation Discussion: #0467 (2018) |
(Issued at 413 PM EDT MON JUL 16 2018
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0467
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
413 PM EDT MON JUL 16 2018
AREAS AFFECTED......EASTERN KENTUCKY...SOUTHERN OHIO...SOUTHERN
WEST VIRGINIA...EASTERN TENNESSEE...SOUTHWEST VIRGINIA...WESTERN
NORTH CAROLINA...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 162012Z - 170112Z
SUMMARY...THUNDERSTORMS WILL CONTINUE TO CONGEAL AHEAD OF A
MESO-CONVECTIVE VORT MAX (MCV), WITH SOME TRAINING EXPECTED GIVEN
THE OVERALL LIGHT STEERING FLOW. HOURLY RAIN RATES OF 2+ INCHES
WILL LEAD TO POTENTIAL FLASH FLOOD CONCERNS WHERE STORMS ARE
BETTER CLUSTERED AND MOST PERSISTENT.
DISCUSSION...AN MCV OVER NORTHERN KY DURING MID AFTERNOON WAS
CONTINUING TO SHAPE THE CONVECTIVE ENVIRONMENT DOWNSTREAM...MOST
NOTABLY WITH THE UPTICK IN S-SW LOW-LEVEL FLOW (15-20+ KTS) PER
THE CURRENT VAD WIND PROFILES. STRONG DEEP-LAYER INSTABILITY (SB
CAPES 2000-3000 J/KG) WITHIN A HIGHLY MOIST ENVIRONMENT (PWATS
1.75-2.00) WILL FAVOR THE BETTER ORGANIZED/NUMEROUS CONVECTIVE
CLUSTERS INTO THE EARLY EVENING HOURS AHEAD OF THE MCV. MEANWHILE,
GIVEN THE WEAK STEERING FLOW (WESTERLY 850-300 MB MEAN WIND AROUND
5-10 KTS), THE INCREASE IN LOW-LEVEL INFLOW WILL FOSTER UPWIND
PROPAGATION AND THUS THE POTENTIAL FOR BACKBUILDING AND CELL
TRAINING.
WHEN COMPARED TO THE OBSERVATIONAL TRENDS (COMPOSITE RADAR AND
RECENT GOES-16 SATELLITE IR AND VISIBLE LOOPS), IT APPEARS THE
MESOSCALE GUIDANCE (HIGH-RES CAMs) ARE HAVING A DIFFICULT TIME
RESOLVING THE QPF DETAILS. THIS IS LIKELY DUE TO THE WEAK OVERALL
FLOW AND THUS TENDENCY FOR THE CONVECTION TO BE SHORT-LIVED.
HOWEVER, THE AVAILABILITY OF FOCUSED, STRONGER LOW-LEVEL INFLOW
AHEAD OF THE MCV AND ATTENDANT N-S VORT AXIS WOULD FAVOR FOR MORE
REPETITIVE CONVECTIVE CLUSTERS, I.E. OUTSIDE OF THE TYPICAL PULSE
CONVECTIVE LIFE CYCLE. AS SUCH, RAINFALL RATES UP TO 2 INCHES PER
HOUR AND 2-2.5+ INCHES IN 3 HOURS ARE EXPECTED IN THIS ENVIRONMENT
UNDERNEATH THE STRONGEST CELLS, WHICH COULD LEAD TO FLASH FLOODING
CONSIDERING THE CURRENT FFG.
HURLEY
ATTN...WFO...FFC...GSP...ILN...JKL...LMK...MRX...OHX...RLX...
RNK...
ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...
LAT...LON 39488209 39178085 38408013 37118012 35618115
34238243 33758359 33978455 34568515 35208525
36368448 37268461 38508418 39158339
Last Updated: 413 PM EDT MON JUL 16 2018
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