Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 281609 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 1209 PM EDT THU APR 28 2016 .UPDATE...
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ISSUED AT 1209 PM EDT THU APR 28 2016 SHOWERS AND STORMS THAT MOVED ACROSS EASTERN KENTUCKY THIS MORNING HAVE LONG SINCE DISSIPATED. NO NEW CONVECTION HAS INITIATED ACROSS THE AREA FOR ABOUT THE LAST 90 MINUTES OR SO. HOWEVER...WITH THE HRRR MODEL STILL SHOWING SOME ISOLATED TO SCATTERED SHOWERS AND STORMS POPPING UP THIS AFTERNOON...AND WITH ENOUGH BREAKS IN THE CLOUDS ACROSS OUR AREA TO AID WITH SURFACE HEATING AND DESTABILIZATION...DECIDED TO LEAVE IN A 20 TO 30 PERCENT CHANCE RAIN ACROSS EASTERN KENTUCKY FOR THE REST OF THE DAY. THE REST OF THE FORECAST WAS IN GOOD SHAPE WITH NO OTHER CHANGES NEEDED. UPDATE ISSUED AT 750 AM EDT THU APR 28 2016 HOURLY GRIDS HAVE BEEN ADJUSTED BASED ON RECENT OBSERVATION...SATELLITE AND RADAR TRENDS. THIS LED TO HIGHER POPS OVER THE NEXT HOUR OR TWO ACROSS THE EASTERN THIRD OF THE REGION. OVERALL...THE RECENT NEAR TERM MODEL GUIDANCE SUPPORTS THE ONGOING CONVECTION MOVING EAST OF THE AREA OVER THE NEXT COUPLE OF HOURS. HOWEVER...WITH THE COLD FRONT AND A SHORTWAVE TROUGH STILL UPSTREAM...REDEVELOPMENT OF CONVECTION AROUND MIDDAY OR EARLY AFTERNOON SEEMS PLAUSIBLE AND IS WHAT THE MOST RECENT HRRR AND RAP RUNS HAVE. SOME OF THAT ACTIVITY COULD BE STRONG TO LOCALLY SEVERE AND PRODUCE HAIL AND STRONG TO LOCALLY DAMAGING WIND GUSTS.
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&& .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 359 AM EDT THU APR 28 2016 EARLY THIS MORNING...A NEARLY STATIONARY FRONT EXTENDED ACROSS THE OHIO VALLEY REGION FROM AN AREA OF LOW PRESSURE OVER THE PLAINS AND MS VALLEY REGION...WITH THE COLD FRONT TRAILING SOUTH INTO THE MID MS VALLEY AND THEN WEST INTO THE SOUTHERN PLAINS. ISENTROPIC LIFT IN ADVANCE OF THIS SYSTEM...LEFTOVER OUTFLOWS AND THE ASSOCIATED MID LEVEL SHORTWAVE IS LEADING TO ISOLATED TO SCATTERED AREAS OF CONVECTION ACROSS THE COMMONWEALTH AND THE APPALACHIAN REGION. AT THIS TIME...THE STRONGEST ACTIVITY IS OVER PARTS OF CENTRAL KY. OVERALL...THE RECENT ACTIVE WEATHER WILL CONTINUE INTO THIS EVENING...BEFORE SHORTWAVE RIDGING AND SFC HIGH PRESSURE BUILD ACROSS THE AREA. THIS WILL LEAD TO CLEARING SKIES TONIGHT INTO FRIDAY MORNING WITH DRY WEATHER AND MILD TEMPERATURES FOR FRIDAY. FOR THE REST OF THE NIGHT INTO THIS EVENING...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE ANTICIPATED AS THE AREA OF LOW PRESSURE TRACKS EAST ACROSS THE OHIO VALLEY BUT TO THE NORTH OF THE AREA AND INTO THE CENTRAL APPALACHIANS THIS EVENING AND THEN TO THE EASTERN SEABOARD BY THE END OF THE PERIOD. THIS LOW WILL SEND A COLD FRONT ACROSS EASTERN AND SOUTH CENTRAL KY DURING THE AFTERNOON AND EVENING HOURS. MEANWHILE A WEAK SHORTWAVE TROUGH WILL MOVE ACROSS THE AREA AS WELL ALTHOUGH THE MAIN MID LEVEL SHORTWAVE WILL TRACK INTO THE GREAT LAKES. ROUNDS OF CONVECTION ARE ANTICIPATED THOUGH CONFIDENCE IN TIMING AND THE DETAILS ARE LOW. THIS PATTERN...HOWEVER...WILL LEAD TO MID LEVEL DRYING AND COOLING TODAY WITH MODEST FLOW IN THE MID LEVELS. SUFFICIENT SOLAR INSOLATION MAY OCCUR FOR CAPE BY MIDDAY INTO THE AFTERNOON TO REACH 1000 J/KG OR HIGHER AT LEAST IN SOME AREAS PENDING MORNING CONVECTION AND CONVECTIVE DEBRIS CLOUDS. AFTER ACTIVITY PROBABLY PEAKS THIS MORNING...A SECONDARY PEAK SHOULD OCCUR IN THE AFTERNOON. THE POTENTIAL EXISTS FOR A COUPLE STRONG TO POSSIBLY SEVERE THUNDERSTORMS THIS AFTERNOON TO EARLY EVENING. MARGINALLY SEVERE HAIL AND LOCALIZED DAMAGING WINDS WOULD BE THE PRIMARY THREATS THOUGH LOCALLY HEAVY RAIN WOULD ALSO BE POSSIBLE. ANY LINGERING CONVECTION DURING THE EVENING SHOULD TAPER OFF FROM WEST TO EAST AS THE COLD FRONT MOVES ACROSS THE AREA AROUND SUNSET. THEREAFTER...THE RESPITE FROM THE RECENT ACTIVE WEATHER WILL BEGIN...THOUGH IT WILL BE SHORT LIVED AS ACTIVE WEATHER IS EXPECTED TO RETURN DURING THE LONG TERM PERIOD...OVER THE WEEKEND. CLEARING SKIES AND LINGERING LOW LEVEL MOISTURE SHOULD SET THE STAGE FOR SOME VALLEY FOG TONIGHT...AND IT COULD BECOME DENSE IN SOME LOCATIONS. CONFIDENCE IN DENSE FOG HOWEVER WAS TOO LIMITED AT THIS POINT TO INCLUDE AS TIMING AND EXTENT OF CLEARING IS UNCERTAIN. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 405 AM EDT THU APR 28 2016 THE PERIOD WILL BE MET WITH INCREASING CLOUDS UPPER LEVEL DIVERGENCE AND UPPER WAVE APPROACHING. ALONG WITH THIS A WARM FRONT WILL PROGRESS NORTH AND ISENTROPIC LIFT WILL BRING INCREASE IN SHOWERS FROM SW TO NE THROUGH THE MORNING AND CONTINUE INTO SATURDAY. DO KEEP SHOWERS IN THE AM BEFORE TRANSITIONING TO CHANCE STORMS IN THE AFTERNOON. BEST CHANCES OF SEEING RAIN WILL BE TOWARD TO AFTERNOON AND EVENING ON SATURDAY AS MAIN WAVE AND LOW LEVEL JET COME ACROSS EASTERN KY. NOW SUNDAY WE SEE MORE PHASING IN THE UPPER LEVELS...WHILE WE RESIDE IN THE WARM SECTOR AT THE SURFACE AS WARM FRONT TRACKS NORTH. THIS PHASING WILL BRING DECENT BAND OF WESTERLIES ALOFT RIGHT ACROSS KY...AND AT THE SURFACE A LOW PRESSURE DEEPENS SOME AS IT APPROACHES THE SOUTHERN OHIO VALLEY. THESE ELEMENTS WILL ALIGN TO ESTABLISH DEEP LAYER SPEED SHEAR...HOWEVER CLOSER TO THE FRONTAL INTERSECTION YOU COULD SEE SOME DIRECTIONAL SHEAR. THE QUESTION WOULD BE HOW MUCH RECOVERY AND DESTABILIZATION DO WE SEE AHEAD OF THIS SYSTEM. THE GFS WOULD SUGGEST WE SEE AMPLY DESTABILIZATION AND CERTAINLY AS THE TROUGH APPROACHES MID LAPSE RATES UP TICK TO AROUND 7 C/KM. CAPE VALUES BECOME FAT WITH IN THE COLUMN...WITH THE SOUNDING SUGGESTING MUCAPE VALUES CLIMBING TO AT OR ABOVE 2000 J/KG. IF WE REALIZE SOME OF THE FORECAST SOUNDINGS WE WOULD BE IN FOR A GOOD CHANCE OF SEVERE WEATHER...AND ALL ELEMENTS OF SEVERE WEATHER WOULD BE IN PLAY. WILL ALSO SAY THE CIPS ANALOG DOES SHOW SOME SIGNAL MAINLY ALONG AND SOUTH OF I64 AND SPC MARS HAS SOME WEAK SIGNAL. GIVEN THE UNCERTAINTIES AND THE FACT THAT WE ARE STILL ABOUT 4 DAYS OUT WILL NOT RAMP UP HWO JUST YET...BUT WORTH WATCHING OVER THE NEXT FEW DAYS. DO TRANSITION THIS TO SHOWERS SUNDAY NIGHT INTO MONDAY AS INSTABILITY LOOKS TO WANE. THIS SYSTEM WILL EXIT TO THE EAST BY MONDAY NIGHT. THESE FALLING HEIGHTS WILL LEAD TO COOLER TEMPS THAN WE HAVE SEEN LATELY...AS WE FALL BACK TO MORE AVERAGE TEMPS FOR THIS TIME OF YEAR. BY TUESDAY MORNING WE DROP BACK INTO THE UPPER 40S FOR LOWS AND THIS MAY FEEL COOL. ANOTHER COLD FRONT MOVES SE LATE WEDNESDAY AND SHOWERS CHANCES INCREASE. BEHIND THIS WE COULD SEE A DECENT SHOT OF COLD AIR IF THE GFS COMES TRUE SHOWING 850 MB TEMPS IN THE 0 TO -2 RANGE...BUT WAY TOO EARLY TO CALL THIS ONE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 755 AM EDT THU APR 28 2016 CONVECTION IS AFFECTING MAINLY JKL AND SJS AND THIS SHOULD SHIFT EAST INTO WV BY 14Z OR 15Z. IFR OR LOWER IS EXPECTED AT TIMES WITH THIS THOUGH MANY LOCATIONS SHOULD ONLY BE REDUCED TO MVFR. ONCE THIS DEPARTS...VFR IS ANTICIPATED. HOWEVER...AN APPROACHING COLD FRONT AND UPPER LEVEL DISTURBANCE COULD LEAD TO REDEVELOPMENT OF ISOLATED TO SCATTERED CONVECTION WITH BRIEF PERIODS OF IFR OR MVFR BY THE 16Z TO 19Z PERIOD. THAT ACTIVITY SHOULD WANE BY 0Z OR SUNSET. LINGERING LOW LEVEL MOISTURE COULD LEAD TO VALLEY FOG WITH MVFR OR IFR VIS BY THE 6Z TO 12 PERIOD. WINDS WILL AVERAGE OUT OF THE SOUTH AT 10KT OR LESS THROUGH 16Z...THEN BECOMING WESTERLY AND GUSTY UNTIL THE COLD FRONT PASSES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...JP LONG TERM...DJ AVIATION...JP

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