Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 021042 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 642 AM EDT THU JUL 2 2015 .UPDATE...
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ISSUED AT 642 AM EDT THU JUL 2 2015 A DECENT RAIN SHIELD IS CURRENTLY MOVING INTO THE WESTERN PORTION OF THE CWA. UPDATED POPS TO BETTER REFLECT ONGOING CONDITIONS AND LIKELY TRENDS THROUGH THE MORNING HOURS. THIS WILL INCLUDE WIDESPREAD RAIN ACROSS MUCH OF THE SOUTHWESTERN CWA...WHICH HAS ALREADY RECEIVED A LARGE AMOUNT OF RAIN OVER THE LAST COUPLE DAYS. GIVEN THE ALREADY SATURATED SOILS...AND ONE HOUR FLASH FLOOD GUIDANCE AN INCH OR LESS IN SOME LOCATIONS...WENT AHEAD AND ISSUED AN HOUR URBAN AND SMALL STREAM ADVISORY FOR ANY RAINS THAT IMPACT THIS AREA OVER THE NEXT FEW HOURS. LUCKILY...IT SEEMS AS THOUGH THIS FIRST LINE OF SHOWERS IS WEAKENING AS IT MOVES INTO THE AREA...BUT EXPECT THEM TO START INTENSIFYING AS THE SUN STARTS WARMING THINGS UP THIS MORNING. ALSO UPDATED THE NEAR-TERM FORECAST FOR TEMPS...DEW POINTS...AND WINDS WITH THE LATEST OBSERVATIONAL DATA.
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&& .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 323 AM EDT THU JUL 2 2015 AS OF 3 AM...LINGERING EVENING CONVECTION OVER THE CWA IS CONTINUING TO DISSIPATE AS BEST ENERGY TURNS ITS ATTENTION TO THE MCS STILL OVER MISSOURI...WHICH IS NOW GENERATING SCATTERED SHOWERS AND THUNDERSTORMS OUT AHEAD OF IT. THESE SHOWERS AND THUNDERSTORMS ARE CURRENTLY MAKING IT INTO WESTERN AND CENTRAL KY/TN AND WILL LIKELY MAKE IT INTO OUR SOUTHERN CWA OVER THE NEXT HOUR OR SO. GIVEN THE HIGH AMOUNT OF RAIN THIS AREA OF OUR CWA HAS SEEN OVER THE LAST COUPLE OF DAYS...AND THE VERY LOW FFG AS OF 0Z 7/02...EXPECT THAT FLOODING CONCERNS WILL LIKELY START ARISING IN THIS AREA JUST BEFORE DAWN AND CONTINUE THROUGH THE MORNING...AND EVEN THROUGH MUCH OF THE DAY. AN UPPER LEVEL SHORTWAVE WILL CONTINUE TO SHIFT ESE TODAY...PULLING THE MCS WITH IT. EXPECT THE HEART OF THE MCS TO BE OVER WESTERN KY AND SOUTHERN IL BY 12Z TODAY...WITH A COLD POOL DRIVEN OUTFLOW PULLING HEIGHTENED CHANCES FOR SHOWERS AND THUNDERSTORMS INTO EASTERN KY. THE MCS WILL CONTINUE TO SHIFT ACROSS THE STATE THROUGH THE DAY FOLLOWING AN SHORTWAVE AS IT ROUNDS AN UPPER LEVEL LONGWAVE TROUGH. AS IT SHIFTS EASTWARD...IT WILL BECOME MORE COLD POOL DRIVEN ONCE MORE WITH MULTIPLE OUTFLOWS LIKELY CREATING THEIR OWN MEANS FOR MULTIPLE AREAS OF CONVECTION. DESPITE WIDESPREAD HEAVY RAIN THROUGH THE DAY AND INTO THE OVERNIGHT HOURS...WPC AND OTHER MODELS ARE STILL PEGGING THE SOUTHERN HALF OF THE CWA WITH THE HIGHEST QPF AMOUNTS. AS MENTIONED ABOVE...THIS IS THE SAME AREA THAT HAS ALREADY BEEN HARD HIT...SO EXPECT AN ACTIVE DAY AND OVERNIGHT PERIOD AS ANY RAIN THAT OCCURS WILL LIKELY RESULT IN RUNOFF. WILL KEEP WITH CURRENT FF WATCH...AS THIS SEEMS TO LINE UP WELL WITH LATEST GUIDANCE AND WPC QPF FORECAST. THERE IS SOME DISCREPANCIES IN THE ECMWF AND THE NAM12 LATE TONIGHT AS THE MCS REACHES THE FAR EASTERN EXTENT OF THE CWA. THE NAM SHOWS A BROADER SURFACE LOW PRESSURE SYSTEM FORMING AND KEEPS MULTIPLE HEAVIER WAVES OF PRECIP OVER SOUTHERN AND EASTERN KY THROUGH 12Z FRIDAY. MEANWHILE...THE ECMWF HAS A SLIGHTLY WEAKER BUT MORE CENTRALIZED LOW...AND PULLS MOST OF THE MOISTURE OUT OF THE STATE WITH THE EXCEPTION OF FAR EASTERN KY BY THIS SAME TIME. REGARDLESS...EXPECT THERE WILL BE SOME DEGREE OF RAIN POTENTIAL CENTERED OVER OUR CWA...WHICH WARRANTED KEEPING LIKELY AND ABOVE POPS ACROSS MUCH OF THE CWA THROUGH THE NIGHT. FOR FRIDAY...ANY LINGERING MOISTURE ACROSS THE STATE WILL LIKELY RESULT IN A RESPARKING OF SCT TO NUMEROUS SHOWERS AND THUNDERSTORMS DURING THE DAYTIME HOURS DUE TO PEAK HEATING AND INTERACTION WITH A STALLED FRONTAL BOUNDARY PASSING THROUGH THE STATE /ATTACHED TO THE DEPARTING LOW/. WHILE CONVECTION WILL GENERALLY BE IN AND AROUND THE AREA OF THE BOUNDARY...EXPECT COVERAGE TO INCLUDE A WIDE AREA ACROSS MOST OF THE STATE AND AREAS SE. ONE THING TO NOTE...HOWEVER...IS THAT MODEL SOUNDINGS ARE SHOWING A LARGE INFLUX OF DRY AIR IN THE MID AND UPPER LEVELS AFTER THE SHORTWAVE/MCS/AND SURFACE LOW PASS THROUGH. THIS WILL KEEP MOST MOISTURE CONFINED TO A SHALLOW LLVL LAYER. LATEST NAM12 FORECAST SOUNDINGS ARE ALSO SHOWING AN INVERSION AT ALL TAF SITES JUST ABOVE THIS MOIST LAYER. WITH THIS IN MIND...EXPECT STRONG TO SEVERE STORM POTENTIAL TO BE VERY LIMITED WITH THIS INVERSION IN PLACE...AND ANY SHOWERS TO BE MUCH LIGHTER IN NATURE WITH LOWER QPF VALUES. THIS CORRELATES WELL WITH THE END OF THE WATCH PERIOD AS WELL. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 455 AM EDT THU JUL 2 2015 AN WAVERING FRONTAL BOUNDARY IS EXPECTED TO SINK SLOWLY SOUTHWARD FROM THE REGION DURING THE PERIOD. ITS PROXIMITY WILL SUPPORT A CONTINUING POSSIBILITY OF SHOWERS AND THUNDERSTORMS. HOWEVER... ENOUGH DRIER AIR MAY MAKE IT INTO THE REGION TO LOWER THE POP SUNDAY THROUGH MONDAY...BEFORE ANOTHER WEAKENING COLD FRONT MOVING IN FROM THE NORTHWEST BRINGS AN INCREASE IN THE POP TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 142 AM EDT THU JUL 2 2015 WHILE MOST SHOWERS AND THUNDERSTORMS HAVE DISSIPATED ACROSS EASTERN KY...ANOTHER AREA OF HEAVY RAIN AND THUNDERSTORMS ASSOCIATED WITH A MCS JUST MOVING INTO THE MISSISSIPPI RIVER VALLEY IS MAKING ITS WAY ACROSS CENTRAL KY AND TN...AND SHOULD BEGIN IMPACTING THE EASTERN PORTION OF THE STATE OVER THE NEXT FEW HOURS. WENT AHEAD AND KEPT MENTION OF VCSH THROUGH THE REST OF THE NIGHT...THOUGH MAY NEED TO UPDATE TAF IF ANY ONE LOCATION IS EXPECTED TO SEE RAIN FOR A PROLONGED PERIOD OF TIME. DESPITE LOW CLOUD COVER /GENERALLY IFR/...THERE IS ENOUGH MOISTURE THAT FOG IS STILL POPPING UP AT TAF SITES AS WELL. UNFORTUNATELY...THE VIS WILL LIKELY FLUCTUATE THROUGHOUT THE NIGHT UNDER A TRUE PATCHY DENSE FOG ENVIRONMENT...SO TRIED TO GEAR TAF TOWARD WORST CONDITIONS EXPECTED. AS THE MCS CONTINUES TO APPROACH FROM THE WEST...EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS BY DAYBREAK AND THROUGH THE DAY TOMORROW. VIS AND CIGS WILL LIKELY BE DEPENDENT ON ANY PASSING STORMS...BUT GENERAL CONDITIONS SHOULD LIE SOMEWHERE BETWEEN IFR AND MVFR DUE TO THE LOW CLOUD DECK EXPECTED TO BE IN PLACE. BY TOMORROW NIGHT...ANY RESIDUAL MOISTURE WILL LIKELY LEAD TO FOG ONCE MORE...DESPITE LINGERING LOW CIGS AND SHOWERS. OUTSIDE OF ANY STORMS...WINDS WILL BE LIGHT THROUGH THE PERIOD...AT AROUND 5 KTS OR LESS OVERNIGHT AND 10 KNOTS OR LESS DURING THE DAY...AND GENERALLY FROM THE SOUTHWEST. && .JKL WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR KYZ068-069-079-080- 083>088-114>118. && $$ UPDATE...JMW SHORT TERM...JMW LONG TERM...HAL AVIATION...JMW

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