Area Forecast Discussion
Issued by NWS Jackson, KY

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120 FXUS63 KJKL 271740 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 140 PM EDT WED APR 27 2016 .UPDATE... ISSUED AT 1140 AM EDT WED APR 27 2016 THE FORECAST WAS UPDATED LATE THIS MORNING TO ACCOUNT FOR THE LATEST TRENDS IN RADAR IMAGERY AND THE LATEST RUN OF THE HRRR MODEL. RAIN SHOWERS HAVE BEEN MORE PERSISTENT AND WIDESPREAD THIS MORNING THAN PREVIOUSLY FORECAST. WE HAVE ALSO BEEN SEEING SPORADIC LIGHTNING STRIKES THROUGH OUT THE MORNING THAT WERE NOT PREVIOUSLY FORECAST EITHER. THE HRRR MODEL SEEMS TO HAVE A GOOD HANDLE ON THE EVOLUTION OF THIS MORNINGS SHOWER AND STORM ACTIVITY...THEREFORE...PRECIPITATION CHANCES FROM 13Z THIS MORNING THROUGH THE REST OF THE AFTERNOON WERE INCREASED TO ACCOUNT FOR MODEL DATA AND ACTUAL OBS ACROSS THE REGION. THE PRECIPITATION AMOUNTS FOR TODAY WERE ALSO INCREASED TO ACCOUNT FOR THE MORE WIDESPREAD PRECIPITATION THAT WE HAVE ALREADY HAD AND ARE ANTICIPATING THE REST OF TODAY. UPDATE ISSUED AT 626 AM EDT WED APR 27 2016 WSR-88D IS TRACKING SCATTERED SHOWERS ACROSS A GOOD PORTION OF EASTERN KY THIS MORNING. WE HAVE BEEN SPARED THE THUNDER THIS MORNING UNLIKE PORTION OF CENTRAL KY...BUT DID ADD ISOLATED BY LATE MORNING TO EARLY AFTERNOON IN CASE SOME OF THIS ACTIVITY PROPAGATES INTO THE REGION. OVERALL ADJUSTED POPS TO REFLECT THE RADAR TRENDS. OTHERWISE JUST A FEW MINOR ADJUSTMENTS TO TEMPS/DEWS/WINDS WITH LATEST OBS AND TRENDS. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 400 AM EDT WED APR 27 2016 THIS MORNING WSR-88D RADAR IS SHOWING SOME RAIN SHOWER ACTIVITY ACROSS PORTION OF EASTERN KY. MORE OF A SCATTERED COVERAGE OVERALL AND RIGHT NOW THE LATEST HRRR SEEMS TO BE HANDLING THIS...HOWEVER THE NMM/ARW SEEM TO BE OVERDONE ON THE UPSTREAM SHOWERS. JUST CAN NOT JUSTIFY THE MORE ROBUST POP CAMS ARE PAINTING GIVEN THE CLOUD TOP WARMING TREND BASED ON IR SAT. NOW THE REST OF THE DAY STILL REMAINS IN QUESTION. CAMS DO REDEVELOP CONVECTION THIS AFTERNOON AND WOULD PROBABLY RESIDE ALONG LEFT OVER BOUNDARIES. HOWEVER GIVEN LACK OF UPPER LEVEL SUPPORT AND EVEN LESS SHEAR THAN YESTERDAY...WOULD THINK ANY CONVECTION THAT FIRES WOULD BE FAIRLY DISORGANIZED. HOWEVER FELT LIKE SCATTERED CONVECTION COULD NOT BE RULED OUT AND PERHAPS A ISOLATED SEVERE REPORT IF WE REALIZE THE INSTABILITY. OVERALL KEPT BETTER POPS IN THE SW TO MATCH THE SSEO THINKING UNTIL MORE ORGANIZED CONVECTION WOULD ONCE AGAIN RIDE EAST THIS EVENING INTO TONIGHT. THEREFORE BRING MORE NUMEROUS SHOWERS AND SCATTERED STORMS AFTER 00Z...AND WOULD THINK OVERALL BETTER CHANCES WOULD RESIDE ALONG AND NORTH OF THE MOUNTAIN PARKWAY. GENERALLY THINK CONVECTION WILL WANE OVERNIGHT AND ISOLATED STORM WOULD BE THE STORY OVERNIGHT INTO EARLY THURSDAY. NOW FOR THURSDAY THERE LOOKS TO BE ONGOING CONVECTION EARLY ON AS MENTIONED ABOVE. WE THEN LOOK TO AN APPROACHING COLD FRONT FROM THE CENTRAL PLAINS...AT THE SAME TIME AN UPPER LEVEL CLOSED LOW EJECTS NE INTO THE UPPER MS VALLEY REGION. THIS WILL LEAD TO FALLING HEIGHTS AND LIFTING FROM THE BOUNDARY. TIMING SEEMS TO BE THE BIGGEST QUESTION AND HOW MUCH CAN WE GET TO DEVELOP GIVEN THE EARLY ON CONVECTION. HOWEVER THE WESTERLIES ALOFT BEGIN TO PICK UP WITH DEEP LAYER SHEAR OF 35 TO 40 KNOTS. THE MODEL SOUNDING FROM BOTH THE NAM AND GFS WOULD SUGGEST DCAPES APPROACHING THE 1000 J/KG RANGE...STEEP LOW LEVEL LAPSE RATES...AND AMPLY MID LEVEL DRYING WHICH WOULD LEAD TO POTENTIAL FOR DAMAGING WIND GUSTS. THE HAIL THREAT WOULD ALSO BE THERE WITH DECENT BUOYANCY IN THE HAIL GROWTH ZONE...AFOREMENTIONED DEEP LAYER SHEAR...AND FREEZING LEVELS LOWERING...BUT OVERALL THE STRONGER SIGNALS SEEM TO POINT TO MORE OF A WIND THREAT. ALSO THERE ARE CERTAINLY SOME SIGNALS WITH RESPECT TO THE CIPS ANALOG FOR THURSDAY. HOWEVER RIGHT NOW GIVEN SOME OF THE UNCERTAINTY AKA MARGINAL SPC RISK...AND WITH RESPECT TO MOST OF THE SHORT TERM MODELS MODEST SIGNAL THURSDAY AFTERNOON...WILL HOLD OFF ON STRONGER MENTION IN THE HWO. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 435 AM EDT WED APR 27 2016 THE MODELS HAVE COME INTO BETTER AGREEMENT THROUGH THE LONG TERM PERIOD...WITH ACTIVE WEATHER PATTERN STILL ANTICIPATED VERY EARLY IN THE LONG TERM PERIOD AND THEN AGAIN OVER THE WEEKEND INTO NEXT WEEK. AN UPPER LEVEL SHORTWAVE TROUGH SHOULD DEPART TO THE NORTHEAST THU NIGHT INTO FRIDAY WITH UPPER LEVEL RIDGING MOVING ACROSS THE AREA RATHER QUICKLY FRIDAY INTO FRIDAY NIGHT...BRINGING A DRY END TO THE WORK WEEK. MEANWHILE...A TROUGH IS STILL EXPECTED TO TAKE SHAPE ACROSS THE WESTERN CONUS...WITH A SERIES SHORT WAVES EJECTING EASTWARD AND NORTHEAST ACROSS THE PLAINS AND INTO THE MS AND OH VALLEYS FRI INTO SUN. EARLY NEXT WEEK...A MORE SIGNIFICANT SHORTWAVE MOVING FROM ROCKIES AND INTO THE NORTHERN AND CENTRAL PLAINS TO END THE WEEKEND TO EARLY NEXT WEEK SHOULD INTERACT OR MERGE WITH A NORTHERN STREAM SHORTWAVE TROUGH ACROSS EASTERN CANADA. THIS SHOULD SHARPEN UP A TROUGH OVER ONTARIO AND QUEBEC AND THE GREAT LAKES. THE AXIS OF THE INITIAL SHORTWAVE TROUGH GENERALLY PASSING NORTH SHOULD BE WORKING INTO THE AREA EARLY IN THE PERIOD. THIS SHOULD LEAD TO CONVECTION EXITING ON THURSDAY NIGHT. FRIDAY AND FRIDAY NIGHT WILL BE DRY...WITH HIGH PRESSURE DOMINATING. HOWEVER... ADDITIONAL MOISTURE AND FORCING ARRIVE FROM THE WEST ON SATURDAY AS SHORTWAVES BEGIN TO ARRIVE FROM THE SOUTHWEST. THE ECMWF AND GFS REMAIN IN GOOD AGREEMENT WITH THE TIMING OVER THE WEEKEND...AND WE CONTINUE TO STAY CLOSE TO THE THE MODEL BLEND. THE BEST RAIN CHANCES SHOULD OCCUR SUNDAY INTO SUNDAY EVENING AS A MORE DEFINED SHORT WAVE TROUGH MOVES ACROSS THE OHIO AND TENNESSEE VALLEYS AND MOISTURE SHOULD BE DEEPEST. A GOOD SOAKING RAIN DURING THE WEEKEND IS ANTICIPATED AND AMOUNTS NEARING OR EXCEEDING AN INCH ARE POSSIBLE FROM SATURDAY INTO SUNDAY NIGHT. LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE IF STRONGER SHOWERS OR STORMS TRAIN. TROUGHING WILL LINGER INTO TUESDAY...JUSTIFYING AT LEAST LOW CHANCE POPS. THE 0Z ECMWF AND 0Z GFS HOWEVER INDICATE THE POSSIBILITY OF A REPRIEVE FOR MUCH OF TUESDAY AND LINGERING AFTER THE PERIOD. WE HAVE CONTINUED TO UNDERCUT THE MODEL BLEND POPS ON TUESDAY UNTIL OR IF CONFIDENCE INCREASES THAT A DRY PERIOD OR TWO SHOULD OCCUR. HIGH TEMPERATURES WILL AVERAGE ABOVE NORMAL THROUGH THE END OF THE WEEK...AND THEN LOOK TO COOL SLIGHTLY BACK TO AROUND OR SLIGHTLY BELOW NORMAL TO START NEXT WEEK. CLOUD COVER SHOULD LIMIT DIURNAL RANGES THUS OVERNIGHT LOWS WILL AVERAGE ABOVE NORMAL. && .AVIATION...
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(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 140 PM EDT WED APR 27 2016 THE AIRPORTS AROUND EASTERN KENTUCKY WILL EXPERIENCE PERIODS OF SHOWERS AND THUNDERSTORMS...ALONG WITH CORRESPONDING MVFR CONDITIONS...THROUGH OUT THE TAF PERIOD. DURING TIMES WHEN NO SHOWERS OR STORMS ARE AFFECTING A PARTICULAR TAF SITE...VFR CONDITIONS SHOULD PREVAIL. THE CLOUDS AND PRECIPITATION WILL BE MOST WIDESPREAD THROUGH AROUND 10Z ON THURSDAY. AFTER THAT...THE SHOWERS AND STORMS ARE EXPECTED TO GRADUALLY TAPER OFF. WINDS WILL BE LIGHT AND VARIABLE IN GENERAL...WITH STRONGER GUSTIER WINDS ACCOMPANYING ANY SHOWERS AND STORMS.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...DJ LONG TERM...PG/JP AVIATION...AR

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