Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 251913 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 313 PM EDT MON MAY 25 2015 .UPDATE... ISSUED AT 1252 PM EDT MON MAY 25 2015 ONCE AGAIN...HAVE MAINLY UPDATED TO BLEND OBS INTO THE FORECAST. UPDATE ISSUED AT 926 AM EDT MON MAY 25 2015 UPDATED SKY CONDITION TO BLEND MORNING SATELLITE OBS INTO THE DAYTIME FORECAST...BUT WITH LITTLE SUBSTANTIVE CHANGE. OTHER FORECAST ELEMENTS WERE STILL IN GOOD SHAPE. UPDATE ISSUED AT 700 AM EDT MON MAY 25 2015 THE FORECAST APPEARS TO BE ON TRACK SO HAVE JUST UPDATED THE SKY/T/TD GRIDS PER THE LATEST OBS AND TRENDS. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 325 AM EDT MON MAY 25 2015 06Z SFC ANALYSIS SHOWS A TIGHTENING PRESSURE GRADIENT OVER KENTUCKY BETWEEN BROAD LOW PRESSURE IN THE PLAINS AND HIGH PRESSURE ALONG THE EAST COAST. THE INVERSION IN PLACE OVER EASTERN KENTUCKY AND NATURE OF THE TERRAIN IS KEEPING THE WINDS LIGHT TO CALM IN MOST PLACES. THIS...COMBINED WITH A SMATTERING OF HIGH AND MID LEVEL CLOUDS...HAS LED TO ANOTHER NIGHT OF GOOD RADIATIONAL COOLING AND RIDGE TO VALLEY TEMPERATURE SPLITS ACROSS EASTERN PARTS OF THE CWA. READINGS CURRENTLY VARY FROM THE MID 50S IN THE MOST SHELTERED VALLEYS TO THE MID TO UPPER 60S ON THE RIDGES AND IN MORE OPEN LOCATIONS. AS IS OFTEN THE CASE IN THESE SITUATIONS...EKQ SHOWS THE RESULTS OF A WELL MIXED BOUNDARY LAYER WITH SOUTH WINDS GUSTING TO 17 KTS AND TEMPS IN THE LOWER 70S AT LAST OBSERVATION. WHILE DEW POINTS HAVE COME UP DURING THE PAST 24 HOURS THEY ARE STILL ON THE RELATIVELY DRY SIDE RANGING FROM THE LOWER 50S IN THE FAR EAST AND ON RIDGETOPS TO THE MID 50S IN OUR WESTERN COUNTIES AND VALLEY LOCATIONS. THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE UPPER LEVEL PATTERN THROUGH THE SHORT TERM PORTION OF THE FORECAST. THEY ALL DEPICT A SHARP RIDGE PUSHED FURTHER EAST FROM THE AREA IN THE FACE OF A BROAD AND OPENING TROUGH CROSSING THE MID MISSISSIPPI VALLEY TODAY. A COUPLE SIGNIFICANT SHORTWAVES WILL PASS THROUGH THE REGION JUST TO THE NORTHWEST OF EAST KENTUCKY. THE FIRST OF THESE GOES BY FROM LATE THIS MORNING THROUGH THE AFTERNOON RESULTING IN FURTHER HEIGHT FALLS. AFTER A QUIET NIGHT...A MORE SUBSTANTIAL WAVE PASSES ON TUESDAY AFTERNOON IN CONJUNCTION WITH THE BODILY LIFTING TO THE NORTHEAST OF THE CENTRAL TROUGH/S REMNANT CORE. THIS WILL BRING A DECENT MID LEVEL WIND FIELD THROUGH THE AREA AS IT MOVES BY AND LIKELY FUEL STRONGER AND POSSIBLY SEVERE STORMS FOR MUCH OF THE STATE WHEN COMBINED WITH MODERATE INSTABILITY EXPECTED TO BE IN PLACE. HAVE FOLLOWED THE HIGHER RESOLUTION GUIDANCE FROM THE HRRR AND NAM12 MOST CLOSELY GIVEN THE OVERALL MODEL AGREEMENT AND SMALLER SCALE NATURE OF THE DETERMINANT FEATURES. SENSIBLE WEATHER WILL START OFF QUIET ENOUGH FOR THIS HOLIDAY... AND FOLLOWING SEVERAL DAYS OF NEAR PERFECT WX...BUT WILL LIKELY TURN CONVECTIVELY ACTIVE BY MIDDAY STARTING IN THE WESTERN PARTS OF THE CWA AND PUSHING EAST THROUGH THE AFTERNOON. THE EARLIER HRRR RUNS AND HINTS WITHIN THE NAM12 SUGGESTED A POSSIBILITY OF A STRAY SHOWER AROUND EAST KENTUCKY BEFORE 15Z IN ADVANCE OF THE MAIN AREA BOTH MODELS DEVELOP LATER IN THE DAY. THIS APPEARS TO BE OVERDONE...AND NOW DISCOUNTED BY THE LATEST HRRR...GIVEN THE RELATIVELY DRY AIR STILL IN PLACE OVER THE EASTERN PART OF THE STATE. NEVERTHELESS...THEY DO AGREE ON A FAIRLY ACTIVE AFTERNOON FOR MOST OF THE AREA AS THE LEAD MID LEVEL SHORTWAVE INITIATES CONVECTION EARLY ON TO THE WEST AS DIURNAL INSTABILITY ALONG WITH PROGRESSIVE OUTFLOW BOUNDARIES ARE EXPECTED TO DO THE REST. THE ACTIVITY WILL WANE EARLY IN THE EVENING WITH A SMALL CHANCE FOR SHOWERS/STORMS DURING THE TIME OF TYPICAL CONVECTIVE MINIMUM. RENEWAL OF ACTIVITY IS ANTICIPATED FOR TUESDAY AS THE NEXT WAVE BRUSHES BY ALOFT WITH A BETTER WIND FIELD AND AS MUCH...OR POTENTIALLY MORE...INSTABILITY IN PLACE. THE MAIN QUESTION FOR ORGANIZED DEVELOPMENT OF STORMS AND THE OVERALL SEVERE POTENTIAL WILL REST ON PARTIAL CLEARING AND THE ABILITY OF THE AIR MASS OVER EKY TO OVERCOME ANY EARLIER STABILIZING EFFECTS OF CONVECTION/DEBRIS FROM THAT MORNING/S LIMITED CONVECTION. WITH THE POTENTIAL FOR STRONGER STORMS...AND IN CONJUNCTION WITH THE SPC OUTLOOK FOR TUESDAY...WILL HIGHLIGHT CONCERNS IN THE HWO...A WEB HEADLINE...AND A HEADS UP EMAIL TO OUR PARTNERS. THIS SHOULD ENSURE THAT DECISION MAKERS ARE NOT CAUGHT UNAWARE OF THE STORM POTENTIAL COMING OFF A LONG HOLIDAY WEEKEND. USED THE SHORTBLEND AS A STARTING POINT FOR THE T/TD AND WIND GRIDS TODAY BEFORE WRAPPING UP WITH THE SUPERBLEND THROUGH 00Z WEDNESDAY. GIVEN THE INCREASE IN MOISTURE AND CLOUD COVER FOR TONIGHT MADE ONLY MINOR TERRAIN BASED CHANGES TO THE LOW TEMPERATURES. AS FOR POPS...ENDED UP A LITTLE HIGHER THAN EVEN THE WETTER MAV MOS FOR THIS AFTERNOON. FOLLOWING THAT...THE POPS WERE MOST SIMILAR TO THE LOWER MET NUMBERS TONIGHT AND IN LINE WITH A BLEND OF THE FAIRLY HIGH GUIDANCE TUESDAY. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 313 PM EDT MON MAY 25 2015 MOST OF THE CONUS WILL FEATURE A LONGWAVE TROUGHING PATTERN...AS UPPER LEVEL RIDGING /CURRENTLY EXITING EASTERN KY/ REACHES THE SOUTHEAST ATLANTIC COAST AND REMAINS NEARLY STATIONARY JUST OFF THE COAST THROUGH MUCH OF THE EXTENDED. MEANWHILE...MULTIPLE UPPER LEVEL LOWS AND SHORTWAVES MOVE IN FROM THE PACIFIC COAST AND TRAVERSE THE LONGWAVE PATTERN EASTWARD ACROSS THE CONUS. KY WILL GENERALLY FIND ITSELF ON THE LEEWARD SIDE OF THIS TROUGHING AS THE UPPER LEVEL RIDGING KEEPS SLIGHTLY HIGHER HEIGHTS JUST TO OUR EAST. AS SUCH...EXPECT MULTIPLE SHORTWAVES TO TRAVERSE THE LONGWAVE TROUGH AND MOVE NORTHEAST THROUGH KY THROUGH THE EXTENDED. THIS WILL RESULT IN A VERY ACTIVE LONG TERM PERIOD...WITH EACH WAVE BRINGING A RENEWED CHANCE FOR SHOWER AND THUNDERSTORM ACTIVITY TO THE REGION. EACH DAY...EXPECT SOME DEGREE OF SHOWERS AND THUNDERSTORMS ACROSS THE REGION...WITH BEST ACTIVITY AND COVERAGE EXPECTED DURING THE AFTERNOON AND EVENING HOURS DUE TO DAYTIME HEATING HELPING TO PROMOTE BETTER INSTABILITY AND CAPE VALUES IN THE 2 TO 4K J/KG RANGE. AND WITH CONTINUED SOUTHWEST FLOW THROUGHOUT MUCH OF THE PERIOD...EXPECT TEMPS TO CONTINUE TO BE IN THE LOW TO MID 80 RANGE WITH DECENT HUMIDITY DURING THE AFTERNOON HOURS. PWAT VALUES THROUGH THE PERIOD ARE FORECAST TO BE 1.5 INCHES OR HIGHER EACH DAY...SO ANY OF THE SHOWERS AND THUNDERSTORMS THAT DEVELOP WILL LIKELY GENERATE SOME LOCALLY HEAVY RAINFALL. HOWEVER...THAT BEING SAID...OTHER THAN DURING THE DAY WEDNESDAY...MOST OF THE WINDS ALOFT ARE QUITE LIGHT...SO ANY STORMS THAT DEVELOP WILL LIKELY NOT PRODUCE MUCH IN THE WAY OF HIGH WIND GUSTS UNLESS MESOSCALE DRIVEN. AND LATEST MODEL SOUNDINGS ARE SHOWING GOOD SATURATION THROUGHOUT THE COLUMN...LEAVING LITTLE DRYING ALOFT FOR LARGE HAIL DEVELOPMENT. INSTEAD...EXPECT FREQUENT LIGHTNING...SMALL HAIL...AND HEAVY DOWNPOURS TO BE THE MAIN CONCERN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 231 PM EDT MON MAY 25 2015 VFR CONDITIONS PREVAILED AT THE START OF THE PERIOD. SW WINDS WERE GUSTING AROUND 20 MPH NEAR AND NORTH OF INTERSTATE 64. SHOWERS WERE PRESENT JUST TO THE WEST OVER CENTRAL KY. THE PRECIP WILL GRADUALLY MOVE EASTWARD...WITH EASTERN KENTUCKY EXPECTING MVFR IN SHOWERS AT TIMES...ESPECIALLY DURING THE LATE EVENING AND OVERNIGHT HOURS. ISOLATED IFR IS ALSO POSSIBLE. THE WIND SHOULD DIMINISH A BIT TOWARD EVENING. AS TEMPERATURES WARM UP ON TUESDAY...SHOWERS AND THUNDERSTORMS SHOULD START TO REDEVELOP TOWARD THE END OF THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...GREIF LONG TERM...JMW AVIATION...HAL

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