386
AWUS01 KWNH 070921
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-071520-
MESOSCALE PRECIPITATION DISCUSSION 1165
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
520 AM EDT TUE OCT 07 2025
AREAS AFFECTED...PORTIONS OF THE MID SOUTH AND LOWER OHIO VALLEY
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 070920Z - 071520Z
SUMMARY...HEAVY RAINFALL STILL IMPACTING PORTIONS OF THE MID-SOUTH
EARLY THIS MORNING WILL BECOME INCREASINGLY FOCUSED ACROSS THE
LOWER OH VALLEY OVER THE NEXT SEVERAL HOURS. SOME ISOLATED TO
SCATTERED AREAS OF FLASH FLOODING WILL BE POSSIBLE WHERE ANY
CELL-TRAINING OF SHOWERS AND THUNDERSTORMS OCCUR.
DISCUSSION...A WELL-DEFINED SURFACE LOW AND ASSOCIATED MID-LEVEL
VORT CENTER IS BEGINNING TO EDGE INTO THE LOWER OH VALLEY ALONG
WITH A PRONOUNCED SURGE OF TROPICAL MOISTURE. A SOUTHERLY
LOW-LEVEL JET OF 30 TO 40 KTS CONTINUES TO FOCUS RATHER STRONG
WARM AIR ADVECTION AND MOISTURE TRANSPORT AROUND THE EASTERN FLANK
OF THE LOW CENTER, AND THIS COMBINED WITH MODEST INSTABILITY AND
SOME UPPER-LEVEL JET DIVERGENCE SHOULD SUPPORT BROKEN AREAS OF
HEAVY RAINFALL OVERSPREADING THE LOWER OH VALLEY THIS MORNING.
MLCAPE VALUES ARE ONLY ON THE ORDER OF 500 TO 750 J/KG, BUT THE
MOISTURE CONVERGENCE PARAMETERS ARE RATHER STRONG AROUND THE
NORTHEAST FLANK OF THE VORT ENERGY AND ESPECIALLY NEAR THE LOW
CENTER ITSELF. THIS IS FAVORING SOME STRONGER CONVECTIVE ELEMENTS
WITH HIGHLY EFFICIENT RAINFALL OWING TO WARM RAIN/RELATIVELY
SHALLOW-TOPPED CONVECTION. SOME EMBEDDED COLDER CONVECTIVE TOPS
ARE OCCURRING IN SPORADIC BURSTS, AND THESE SMALLER SCALE CLUSTERS
OF CONVECTION HAVE BEEN CAPABLE OF PRODUCING RAINFALL RATES ON THE
ORDER OF 1.5 TO 2.5 INCHES/HOUR.
AS THIS ENERGY BEGINS LIFTING NORTHEASTWARD ACROSS THE LOWER OH
VALLEY THIS MORNING, THERE IS EXPECTED TO BE SOME GRADUAL
INTERACTION WITH AN UPSTREAM COLD FRONT APPROACHING THE OH VALLEY
FROM THE NORTHWEST. THIS WILL SUPPORT A MORE FRONTOGENETICAL
COMPONENT TO THE HEAVY RAINFALL THREAT AND SHOULD SUPPORT A MORE
ELONGATED SOUTHWEST TO NORTHEAST AXIS OF HEAVY RAIN WITH EMBEDDED
CONVECTION.
THE 00Z HREF/REFS SUITES OF GUIDANCE SUPPORT SOME LOCALIZED SWATHS
OF 2 TO 4+ INCHES OF RAIN GOING THROUGH LATE THIS MORNING, WITH A
SPOTTY 5+ INCH TOTAL NOT OUT OF THE QUESTION WHERE ANY
CELL-TRAINING OF CONVECTION OCCURS. THE HEAVIER AND MORE
CONCENTRATED AREAS OF RAINFALL SHOULD BE CLOSE TO THE OH RIVER
INVOLVING AREAS OF FAR SOUTHEAST IL, WESTERN AND NORTHWEST KY AND
INTO FAR SOUTHERN IN.
ANTECEDENT CONDITIONS ACROSS THE REGION ARE GENERALLY ON THE DRY
SIDE, BUT THE RAINFALL POTENTIAL THIS MORNING IS EXPECTED TO BE
ENOUGH TO DRIVE A THREAT FOR ISOLATED TO SCATTERED AREAS OF FLASH
FLOODING. THIS WILL ESPECIALLY BE THE CASE IN VICINITY OF THE MORE
URBANIZED AREAS.
ORRISON
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...ILN...IND...JKL...LMK...MEG...OHX...PAH...
ATTN...RFC...MSR...ORN...TIR...NWC...
LAT...LON 39008471 38588377 37748383 37098453 36388586
36088694 36008780 35988834 36028894 36278967
36758973 37398939 38028844 38508736 38958580
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