Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 220559 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 159 AM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 159 AM EDT FRI AUG 22 2014 A COMPLEX OF THUNDERSTORMS IS CURRENTLY SLIDING SOUTHEAST ACROSS THE SOUTHERN HALF OF OHIO. THIS COMPLEX IS WEAKENING AS EVIDENCED BY THE WARMING CLOUD TOPS OVER THE PAST COUPLE OF HOURS. STILL...FEEL THAT THIS WILL SKIRT THE NORTHEASTERN PORTION OF THE FORECAST AREA WITH MEASURABLE RAINFALL IN THE 06 TO 10Z TIME RANGE...SO BEEFED UP THE POPS TO ACCOUNT FOR THIS FEATURE. UPDATES HAVE BEEN SENT. UPDATE ISSUED AT 1031 PM EDT THU AUG 21 2014 A NEW FORECAST UPDATE WAS JUST SENT OUT ADDRESSING THE POSSIBILITY OF THUNDERSTORMS MOVING FURTHER SOUTH INTO OUR FORECAST AREA LATER TONIGHT THAN PREVIOUSLY THOUGHT. BASED ON CURRENT SATELLITE AND RADAR IMAGERY...IT APPEARS THAT THE NORTHERN 2 OR 3 TIERS OF COUNTIES OF OUR FORECAST AREA COULD EXPERIENCE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A LARGE THUNDERSTORM COMPLEX THAT IS CURRENTLY MOVING ACROSS PARTS OF CENTRAL INDIANA AND WEST CENTRAL OHIO. THE SKY COVER...PRECIPITATION PROBABILITY...WEATHER TYPE...AND PRECIPITATION AMOUNT FORECAST GRIDS WERE ALL UPDATED TO REFLECT CURRENT TRENDS AND THE LATEST HRRR FORECAST DATA. THE HAZARDOUS WEATHER OUTLOOK WAS ALSO UPDATED TO REFLECT THE NEW THUNDERSTORM PROBABILITIES AND THE FURTHER SOUTHWARD MOVEMENT OF THE STORMS THEMSELVES. UPDATE ISSUED AT 758 PM EDT THU AUG 21 2014 SOME SIGNIFICANT UPDATES WERE MADE TO THE FORECAST GRIDS FOR THE REST OF THE TONIGHT INTO EARLY TOMORROW MORNING. WILL BE ISSUING A NEW ZONE FORECAST PRODUCT WITH THE PREFIRST PERIOD FROM DAY SHIFT REMOVED. THE GRIDS AND THE TEXT FORECAST PRODUCT HAVE BOTH BEEN UPDATED TO REFLECT THE FACT THAT ALL PRECIPITATION HAS NOW MOVED OUT OF EASTERN KENTUCKY. THE LATEST NAM12 AND HRRR MODELS BOTH ARE KEEPING PRECIPITATION OUT OF THE AREA UNTIL 8 OR 9Z TONIGHT. BASED ON THIS...AND THE LATEST RADAR IMAGERY...WHICH HAS A LARGE THUNDERSTORM COMPLEX MOVING ACROSS NORTHERN INDIANA...IT APPEARS THAT THE MODEL DATA IS ON TRACK AND THAT THE STORMS CURRENTLY MOVING ACROSS INDIANA WILL STAY MOSTLY NORTH OF THE AREA AS THEY MOVE ACROSS SOUTHERN OHIO LATE TONIGHT AND EARLY TOMORROW. WE MAY SEE A FEW SHOWERS AND STORMS FIRE UP ALONG THUNDERSTORM OUTFLOWS IN OUR NORTHERNMOST COUNTIES ALONG AND NORTH OF I-64 AROUND 8Z TONIGHT. THE SKY COVER GRIDS AND FORECAST WERE ALSO UPDATED TO REFLECT CURRENT TRENDS OF PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE FORECAST AREA. CONSIDERING THE AMOUNT OF RAIN EASTERN KENTUCKY HAS RECEIVED THE PAST SEVERAL DAYS...AND WITH CLOUDS BREAKING UP A BIT TONIGHT...WE SHOULD STILL SEE AREAS OF FOG IN OUR VALLEYS. LOCATIONS THAT RECEIVED RAINFALL TODAY...INCLUDING RIDGETOP LOCATIONS SUCH AS THE JACKSON WEATHER OFFICE...COULD ALSO SEE SOME MVFR FOG OVERNIGHT. THE HAZARDOUS WEATHER OUTLOOK WILL ALSO BE UPDATED SHORTLY TO REFLECT THE LACK OF THUNDER THROUGH DAWN TOMORROW. A NEW SET OF ZONES WILL ALSO BE ISSUED SHORTLY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 355 PM EDT THU AUG 21 2014 19Z SFC ANALYSIS SHOWS A SEASONALLY STRONG AREA OF LOW PRESSURE OVER THE HIGH PLAINS WITH HIGH PRESSURE OVER THE DEEP SOUTH. THIS NEARBY HIGH IS NOT ENOUGH TO PREVENT THE LATEST INCARNATION OF MCS ACTIVITY FROM DIVING THROUGH EASTERN KENTUCKY. THIS IS TAKING ADVANTAGE OF HIGH INSTABILITY THROUGHOUT THE AREA GIVEN TEMPERATURES IN THE UPPER 80S AND DEWPOINTS IN THE LOWER 70S. IN ADDITION TO THE SEVERE THUNDERSTORM THREAT...HIGH PWS...LOW FFG...AND A POTENTIAL FOR TRAINING WILL KEEP FLASH FLOODING A CONCERN THROUGH THE EVENING. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST WITH A LARGE AREA OF RIDGING STRETCHING FROM THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY. AS IT DOES SO...A DEEP LOW TO THE NORTHEAST WILL SEND PACKETS OF ENERGY THROUGH THE OHIO VALLEY AND INTO THE CENTRAL APPALACHIANS IN FAIRLY FAST NORTHWEST FLOW. THIS WILL PLACE AT LEAST NORTHEAST PARTS OF THE JKL CWA IN THE STORM TRACK AND AS PRIME REAL ESTATE FOR MCS ACTIVITY. GIVEN THE MODEL AGREEMENT HAVE FAVORED A BLEND WITH EXTRA EMPHASIS ON THE HRRR AND NAM12 FOR THE FIRST 12 TO 24 HOURS. SENSIBLE WEATHER WILL FEATURE ON GOING THUNDERSTORM ACTIVITY DIMINISHING INTO THE EVENING...BUT PROGRESSING SOUTH WITH THE FAVORED INSTABILITY. LATER TONIGHT...PARTLY CLOUDS SKIES AND THE MOISTURE FROM THE RAIN OF THIS AFTERNOON AND EVENING WILL LIKELY LEAD TO AREAS OF FOG...LOCALLY DENSE. INDICATIONS ARE THAT THE NEXT ROUND OF STORMS STAY TO THE NORTHEAST OF THE CWA TONIGHT. AFTER THE FOG BURNS OFF ON FRIDAY MORNING THE INSTABILITY WILL BUILD AGAIN WITH ANOTHER VERY HUMID AND WARM DAY. THIS WILL BE A SIMILAR SETUP FOR SEVERE AND EXCESSIVE RAIN POTENTIAL...MAINLY IN THE NORTHEAST BASED ON THE EXPECTATION OF EARLY STORMS TRACKING JUST OUTSIDE OF THE CWA AND DEVELOPMENT ON THEIR SOUTHWEST FLANKS. LIKEWISE...PATCHY FOG WILL BE AN ISSUE FOR THE AREA LATER FRIDAY NIGHT GIVEN A SIMILAR SETUP... BUT STILL DEPENDENT ON THE RAINS EARLY IN THE DAY AND EVENING. USED THE CONSSHORT AS A STARTING POINT FOR THE T...TD...AND WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND FRIDAY NIGHT. AS FOR POPS...ENDED UP HIGHER THAN GUIDANCE...EXCEPT FOR THE MET NORTH OF JKL ON FRIDAY NIGHT...THROUGH SATURDAY MORNING OWING TO THE TENDENCY FOR STORMS TO EXPAND SOUTHWEST OF THEIR DEPICTIONS IN THE MODELS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 315 PM EDT THU AUG 21 2014 STRONG RIDGING WILL LIKELY HOLD OVER THE AREA FOR THE BALANCE OF THE EXTENDED PART OF THE FORECAST. SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE EACH DAY THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...WARM AND MUGGY CONDITIONS WILL REMAIN ANCHORED BENEATH THE RIDGE. BEST TIME FOR SHOWERS AND STORMS WILL CONTINUE TO BE EACH AFTERNOON/EVENING...BUT CANNOT RULE OUT AN ISOLATED SHOWER OR STORM AT ANY TIME INTO NEXT WEEK. GFS MOS IS LIKELY A BIT TOO HIGH AND WILL CONTINUE TO GO BETWEEN GFS AND MET MOS THROUGH SATURDAY. ECMWF SEEMS TO BE A GOOD COMPROMISE WITH REGARDS TO TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 159 AM EDT FRI AUG 22 2014 A COMPLEX OF THUNDERSTORMS WILL WEAKEN AS IT SKIRTS BY ACROSS NORTHEASTERN KENTUCKY BETWEEN 06 AND 10Z. THIS WILL LIKELY AFFECT A LINE FROM KSYM TO KSJS BETWEEN 07 AND 09Z. MVFR VISIBILITIES ALONG WITH SOME GUSTY NORTHWESTERLY WINDS UP TO AROUND 20 KTS WILL ACCOMPANY THE LEADING EDGE OF THE SHOWERS AND STORMS. EXPECT MVFR OR WORSE FOG WILL SET IN ACROSS THE REST OF THE AREA THROUGH DAWN...WITH IFR OR WORSE FOG RESTRICTED TO THE DEEPER VALLEYS...PARTICULARLY THOSE THAT SAW RECENT HEAVY RAINFALL. ONCE THE FOG BURNS OFF THROUGH AROUND 13Z...A RENEWED THREAT OF CONVECTION WILL RETURN...MAINLY DURING THE AFTERNOON HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...GREIF LONG TERM...KAS AVIATION...GEOGERIAN

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