Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 132347 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 747 PM EDT SUN JUL 13 2014 .UPDATE... ISSUED AT 554 PM EDT SUN JUL 13 2014 MADE MINOR UPDATES BASED ON LATE AFTERNOON OBS...BUT NO SUBSTANTIVE CHANGES WERE MADE FOR THE OVERALL FORECAST. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 305 PM EDT SUN JUL 13 2014 SEVERE THUNDERSTORM AND HEAVY RAIN THREAT REMAIN THE CONCERNS FOR THE SHORT TERM PORTION OF THE FORECAST. NORTHERN PART OF THE FORECAST AREA REMAINS IN THE DAY 1 SLIGHT RISK AREA WITH THE REMAINDER OF THE FORECAST AREA IN THE DAY 2 SLIGHT RISK. ALSO THE EXCESSIVE RAINFALL OUTLOOK FOR DAY 1 HIGHLIGHTS THE NORTHERN FORECAST AREA AND THE DAY 2 OUTLOOK THE SOUTHEAST PART OF THE FORECAST AREA. HOWEVER THE EVOLUTION OF THE SEVERE THREAT AND THE HEAVY RAIN THREAT REMAINS UNCERTAIN FOR EASTERN KY. ISOLATED TO SCATTERED CONVECTION THAT HAS DEVELOPED OVER THE SOUTHEAST PART OF THE FORECAST AREA AND OVER CENTRAL KY IS EXPECTED TO DIE OFF THIS EVENING WITH LOSS OF DAYTIME HEATING. THE MORE ORGANIZED BROKEN LINE OF CONVECTION THAT HAS DEVELOPED ACROSS OHIO AND INDIANA IS EXPECTED TO PERSIST INTO THE NIGHT. THIS AREA OF CONVECTION HAS DEVELOPED AHEAD OF THE THE INITIAL RATHER NEBULOUS PSEUDO COLD FRONT OR OUTFLOW BOUNDARY AND IN A CORRIDOR OF BETTER INSTABILITY AND SHEAR. THERE IS A SEVERE THUNDERSTORM WATCH JUST TO OUR NORTH FOR THIS AND THERE HAS BEEN A SEVERE REPORT OF 1 INCH HAIL OVER CENTRAL OH. AS THIS LINE DROPS SOUTH THIS EVENING INTO OUR AREA THERE WILL BE LESS SUPPORT FOR SEVERE STORMS...WITH LESS INSTABILITY AND LESS SHEAR. THINKING IS THAT SHOWERS AND THUNDERSTORMS WILL BE LIKELY IN THE NORTHERN PART OF THE FORECAST AREA TONIGHT. WHILE SEVERE THREAT IS POSSIBLE IS LOOKS UNLIKELY. THE SEVERE THREAT ON MONDAY LOOKS GREATER...BUT THERE IS CONSIDERABLE UNCERTAINTY DUE TO THE AMOUNT OF ONGOING SHOWER AND THUNDERSTORM ACTIVITY AND CONVECTIVE DEBRIS CLOUD THAT WILL BE AROUND AT THE START OF THE PERIOD. THE SECONDARY...OR PRIMARY COLD FRONT WHICH WILL BE THE LEADING EDGE OF THE MUCH COOLER AND DRIER AIR WILL MOVE INTO THE FORECAST AREA MONDAY NIGHT. THE SEVERE THREAT ON MONDAY WILL LIKELY BE TIED TO HOW MUCH SUNSHINE CAN BE REALIZED DURING THE AFTERNOON...WITH THE BEST CHANCE FOR SEVERE STORMS OVER THE FAR SOUTH PART OF THE FORECAST AREA. THE OTHER CONCERN IS THE HEAVY RAIN THREAT THROUGH THE ENTIRE SHORT TERM FORECAST PERIOD. WITH PWATS FORECAST TO INCREASE OF 1.7 TO POSSIBLY OVER 2 INCHES FROM LATE TONIGHT INTO MONDAY NIGHT HEAVY RAINERS ARE A DEFINITE CONCERN. STORM MOTION FORECAST TO BE 15 TO 2O KNOTS WILL LIMIT THE TIME THE HEAVIEST RAINS WITH A GIVEN STORM REMAIN OVER A LOCAL AREA...BUT THERE IS A THREAT FOR MULTIPLE STORMS TO AFFECT A GIVEN AREA. THERE IS CONSIDERABLE UNCERTAINTY WITH QPF. GIVEN THAT PART OF THE AREA IS IN D1 DROUGHT AND FLASH FLOOD GUIDANCE IS GENERALLY 2 TO 2.3 INCHES PER HOUR...IT LOOKS UNLIKELY THAT OTHER THAN AN ISOLATED FLASH FLOOD EVENT WOULD OCCUR. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 305 PM EDT SUN JUL 13 2014 THE MODELS BEGIN THE EXTENDED PERIOD IN PRETTY GOOD AGREEMENT. THE LARGE SCALE WEATHER PATTERN FEATURES A ANOMALOUSLY DEEP POSITIVELY TILTED UPPER LOW CENTERED OVER NORTHERN MICHIGAN WITH A TROUGH EXTENDING ACROSS SOUTHERN ILLINOIS. THIS IS A COMPLEX WEATHER SYSTEM AND IT WILL INVOLVE MULTIPLE SURFACE FEATURES MOVING ACROSS EASTERN KENTUCKY. BY TUESDAY MORNING...THE COLD FRONT IS FORECAST TO EXTEND FROM ROWAN TO WAYNE COUNTY. THE FRONT WILL CONTINUE TO MOVE ACROSS THE AREA ON TUESDAY AND WILL HAVE MOVED INTO TENNESSEE AND VIRGINIA BY THE LATE AFTERNOON. THE UPPER TROUGH AXIS WILL HANG IN THERE AND NOT MOVE OUT OF THE AREA UNTIL THURSDAY MORNING. EVEN THOUGH THE TROUGH AXIS MOVES THROUGH THE AREA...THE EASTERN PORTION OF THE AREA WILL CONTINUE TO BE UNDER A WEAK TROUGH. AS A RESULT...THE TEMPERATURES ARE GOING TO STAY BELOW NORMAL AND WILL BE QUITE A PLEASE RELIEF FROM THE TYPICAL JULY HEAT AND HUMIDITY. THE LOW TEMPERATURES ON WEDNESDAY AND THURSDAY MORNING WILL BE NEAR OR AT THE RECORDS LOWS ACROSS EASTERN KENTUCKY. A SHORT WAVE WILL GENERATE OVER THE PLAINS ON THURSDAY NIGHT AND WILL MOVE ACROSS THE AREA ON FRIDAY. A FRONT WILL BE MOVING ACROSS THE AREA AND BRING SOME SHOWERS AND THUNDERSTORMS. THIS FRONT WILL LACK DEEP MOISTURE BECAUSE THE GULF AIR WILL NOT BE ABLE TO MOVE INTO THE AREA BEFORE THE FRONT ARRIVES. BY THIS POINT IN TIME THE MODELS AGREE ON THE GENERAL PATTERN...HOWEVER THE GFS IS A LITTLE FASTER WITH THE TROUGH. THE FRONT WILL BE PUSHED TO THE SOUTH OF THE AREA ON FRIDAY NIGHT...HOWEVER SHOULD MOVE BACK TO THE NORTH ON SATURDAY NIGHT. CONFIDENCE IS HIGH THROUGH FRIDAY...HOWEVER REALLY STARTS TO PLUMMET ON SATURDAY DUE TO THE MODEL DIFFERENCES. BY SUNDAY NIGHT THERE ARE MAJOR PHASING ISSUES WITH THE ECMWF AND GFS. && .AVIATION...
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(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 747 PM EDT SUN JUL 13 2014 AN AREA OF NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS WAS OVER SOUTHERN IN...SOUTHERN OH...AND NORTHERN KY AT TAF ISSUANCE. THEY WERE OCCURRING ALONG AND AHEAD OF A WEAKENING COLD FRONT. THE AREA OF PRECIP IS EXPECTED TO SLOWLY DROP SOUTH TONIGHT. IT WILL LIKELY AFFECT THE NORTHERN PART OF THE JKL FORECAST AREA...BUT ITS SOUTHWARD EXTENT IS QUESTIONABLE. AREAS THAT RECEIVE RAIN CAN EXPECT SOME REDUCTION IN VISIBILITY TONIGHT...MAINLY NORTH OF KJKL. MVFR AND LOCALIZED IFR ARE FORECAST...WITH IMPROVEMENT AFTER SUNRISE. ADDITIONAL DEVELOPMENT OF SHOWERS AND THUNDERSTORMS IS EXPECTED DURING THE DAY ON MONDAY...BUT UNCERTAINTY IN TIMING AND PLACEMENT PRECLUDES ANYTHING MORE THAN VCTS IN TAFS AT THIS POINT.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...SBH LONG TERM...JJ AVIATION...HAL

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