Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 300649 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 149 AM EST FRI JAN 30 2015 .UPDATE...
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ISSUED AT 149 AM EST FRI JAN 30 2015 FRESHENED UP THE HOURLY TEMPERATURES AND DEW POINTS TO BETTER REFLECT THE CURRENT TRENDS. SPOTTY RETURNS ON RADAR REFLECT EITHER LIGHT RAIN OR SNOW SHOWERS ACROSS THE AREA. THE NEXT SHORT WAVE TROUGH WILL ROTATE IN BY AROUND DAWN...BRINGING COLDER AIR WITH IT AND HELPING TO BOLSTER THE SNOW SHOWER ACTIVITY INTO THE MORNING. UPDATE ISSUED AT 711 PM EST THU JAN 29 2015 EVERYTHING BEING REPORTED JUST UPSTREAM THIS EVENING CONTINUES TO BE MAINLY DRIZZLE. THIS WOULD BE SUPPORTED BY MODEL SOUNDINGS SUGGESTING VERY LITTLE ICE IN THE CLOUDS THROUGH THE EVENING. MODEL SOUNDINGS COOL ENOUGH (TO INTRODUCE ICE INTO THE CLOUDS) TOWARDS MIDNIGHT TO FINALLY SEE SOME SNOW ENTERING THE PICTURE. ADJUSTED WEATHER THROUGH THE EVENING TO REFLECT MORE DRIZZLE, BEFORE GOING WITH RAIN SHOWERS LATE EVENING...BEFORE QUICKLY MIXING WITH OR CHANGING TO SNOW. SUB- FREEZING TEMPERATURES ARE STILL WELL UPSTREAM AND WILL TAKE A GOOD CHUNK OF THE NIGHT TO SEE THEM GET HERE...BUT IT LOOKS LIKE SOMETIME AFTER 2 AM WE SHOULD SEE THOSE SUBFREEZING TEMPS WORKING INTO OUR AREA.
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&& .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 358 PM EST THU JAN 29 2015 A SURFACE COLD FRONT WAS ENTERING THE JKL FORECAST AREA FROM THE NW AT MID AFTERNOON. AS IS OFTEN THE CASE...COLD AIR ADVECTION WILL LEAD TO STEEP LOW LEVEL LAPSE RATES...AND WHEN COMBINED WITH UPSLOPE FLOW...SHALLOW CONVECTIVE PRECIP SHOULD DEVELOP. IT WILL BE FURTHER AIDED BY THE SUPPORT OF THE MID/UPPER LEVEL TROUGH AXIS PASSING OVER TONIGHT AND EARLY FRIDAY. INITIALLY...THE TEMPERATURE PROFILE SUPPORTS PRECIP IN THE FORM OF RAIN THIS EVENING. AS THE COLUMN COOLS...SURFACE TEMPS WILL COOL ENOUGH TO ALLOW SNOW...AND THE UPPER PART OF THE MOISTURE COLUMN WILL EVENTUALLY REACH -10C AND COLDER...AND PRECIP WILL CHANGE TO SNOW. THE PRECIP AMOUNTS WILL BE LIGHT...BUT THE PROBABILITY IS FAIRLY HIGH. SNOWFALL WILL GENERALLY BE A HALF INCH OR LESS...BUT SOME AMOUNTS OF AROUND AN INCH MAY OCCUR AT HIGHER ELEVATIONS IN THE SOUTHEAST. THE LAST OF THE SNOW SHOWERS WILL TAPER OFF DURING THE DAY FRIDAY AS HIGH PRESSURE BUILDS IN AND UPSLOPE FLOW IS LOST. MOSTLY CLEAR SKIES ARE EXPECTED AS THE SURFACE HIGH PASSES OVER ON FRIDAY NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 358 PM EST THU JAN 29 2015 THIS PERIOD STARTS OUT QUIET WITH HIGH PRESSURE OVERHEAD AND TEMPERATURES NEAR 40 DEGREES...THANKS IN PART TO SOUTHWESTERLY WINDS. SKIES WILL BE MOSTLY CLEAR IN THE MORNING WITH INCREASING CLOUDS IN THE AFTERNOON AS THE NEXT STORM SYSTEM APPROACHES THE REGION. THERE IS STILL A LOT OF UNCERTAINTY WITH THIS LATE WEEKEND SYSTEM DUE TO THE MODEL RUN TO RUN DIFFERENCES. BOTH THE ECMWF/GFS MODELS BRING SOUTHERN STREAM ENERGY FROM THE SOUTHWESTERN US LOW AND TRY TO PHASE IT WITH THE NORTHERN STREAM ENERGY AS IT CROSSES THE TENNESSEE VALLEY. HOWEVER... THE TRACK AND STRENGTH OF THE SFC LOW THAT DEVELOPS IN THE MODELS IS WHERE THERE ARE SUBSTANTIAL RUN TO RUN DIFFERENCES....ESPECIALLY WITH THE LATEST 12Z/29 GFS RUN WHICH DEEPENS THE SFC LOW AND TAKES IT UP ACROSS MASSACHUSETTS. ONE THING THE MODELS DO HAVE IN COMMON IS THE AMOUNT OF QPF THEY SHOW. ANOTHER QUESTION THAT REMAINS IS HOW MUCH COLD AIR STAYS IN PLACE AND THIS WILL HEAVILY DEPEND ON THE TRACK OF THE SFC LOW. THAT BEING SAID... HAVE LEANED A BIT TOWARD A COLDER SOLUTION ON SUNDAY. MODEL SOUNDINGS HAD MOST OF THE MOIST COLUMN BELOW ZERO WITH SFC TEMPS JUST ABOVE FREEZING UNTIL LATE SUNDAY NIGHT. OVERALL CONFIDENCE IN THIS SYSTEM REMAINS LOW. THOUGH...STILL BELIEVE THERE IS A REASONABLE CHANCE FOR MEASURABLE SNOW SUNDAY INTO MONDAY. AS THE SYSTEM DEPARTS HIGH PRESSURE ONCE AGAIN BUILDS INTO THE REGION...ALONG WITH A COLD AIR MASS. THIS SHOULD ALLOW TEMPERATURES TO GENERALLY BE FALLING THROUGHOUT THE DAY ON MONDAY. LOWS MONDAY NIGHT COULD REACH THE SINGLE DIGITS IN SPOTS BUT SHOULD MAINLY BE IN THE LOW TO MID TEENS. TEMPERATURES SHOULD REBOUND ON TUESDAY INTO THE MID TO UPPER 30S IN RESPONSE TO SOUTHERLY FLOW FROM THE GULF USHERING IN WARMER AIR. WEDNESDAY ANOTHER SYSTEM MOVES INTO KENTUCKY BRINGING ANOTHER CHANCE FOR A MIXED PRECIP EVENT ENDING ON THURSDAY. AN ARCTIC AIR MASS ADVECTS IN BEHIND IT... DROPPING TEMPS ONCE AGAIN INTO THE LOW TEENS AND SINGLE DIGITS. FRIDAY WILL BE A CHILLY BUT QUIET DAY WITH HIGHS WELL BELOW NORMAL. && .AVIATION...
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(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 149 AM EST FRI JAN 30 2015 MVFR/IFR CEILINGS WILL CONTINUE ACROSS THE AREA THROUGH THE EARLY AFTERNOON. A PASSING UPPER LEVEL DISTURBANCE SHOULD ALSO BRING A WINDOW OF SNOW SHOWERS TO THE AREA GENERALLY BETWEEN 11 AND 17Z. HIGH PRESSURE WILL THEN BUILD INTO THE REGION...WITH VFR CONDITIONS RETURNING BY LATER THIS AFTERNOON. W TO NW WINDS OF AROUND 10 KTS...WITH OCCASIONAL GUSTS IN THE 15 TO 20 KT RANGE WILL CONTINUE THROUGH THE DAY...BEFORE DIMINISHING TOWARDS DUSK.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...HAL LONG TERM...JVM AVIATION...GEOGERIAN

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