Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 200806
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
306 AM EST SAT DEC 20 2014

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 306 AM EST SAT DEC 20 2014

THE LATEST RUNS OF MOST OF THE FORECAST MODELS HAVE PICKED UP ON THE
FACT THAT LITTLE IF ANY PRECIPITATION IS REACHING THE GROUND ACROSS
CENTRAL AND EASTERN KENTUCKY SO FAR THIS MORNING. SURFACE OBS FROM
AROUND THE STATE OF KENTUCKY HAVE BEEN SHOWING NO MEASURABLE PRECIP
ACROSS THE AREA FOR THE PAST FEW HOURS. AN UPPER LEVEL DISTURBANCE
HAS BEEN PRODUCING WIDESPREAD CLOUD COVER ACROSS THE AREA
TONIGHT...BUT NO MUCH MORE THAN THAT THUS FAR. WITH THIS SYSTEM
QUICKLY PULLING OFF TO THE EAST ACROSS THE OHIO VALLEY...AND WITH NOT
MUCH IN THE WAY OF LOW LEVEL MOISTURE IN PLACE...THE CURRENT THINKING
IS THAT LITTLE IF ANY PRECIPITATION WILL OCCUR AT ANY POINT DURING
THE REMAINDER OF THE OVERNIGHT PERIOD OR DURING THE DAY TODAY. THAT
BEING SAID...HAVE LOWERED PRECIPITATION CHANCES FROM NOW THROUGH
EARLY THIS AFTERNOON BY QUITE A BIT...AND HAVE THE ENTIRE AREA PRECIP
FREE BY 18Z. THE ONLY REASON EVEN LOW SLIGHT CHANCE POPS WERE LEFT IN
THE FORECAST IS THE FACT THAT A NUMBER OF PRECIP TYPE ECHOES ARE
STILL SHOWING UP ON RADAR IMAGERY FROM AROUND THE AREA. ALSO...THE
MODEL SOUNDINGS ARE STILL SHOWING A VERY SMALL CHANCE THAT SOME
MEASURABLE PRECIP COULD REACH THE GROUND OVER THE NEXT SEVERAL HOURS.
WILL GO WITH THIS THINKING FOR NOW...BUT MAY NEED TO UPDATE THE
FORECAST BEFORE THE END OF THE SHIFT IF THINGS DO NOT PAN OUT AS PLANNED.

TEMPERATURES WILL CONTINUE TO RUN SLIGHTLY BELOW NORMAL TODAY DUE TO
EXTENSIVE CLOUD COVER AND NORTHERLY WINDS. TEMPERATURES ON SUNDAY ARE
EXPECTED TO BE SLIGHTLY WARMER THAN NORMAL...AS EAST TO SOUTHEASTERLY
FLOW SETS UP DOWNSLOPE WARMING ACROSS THE AREA AND CLOUDS THINS OUT
BEHIND THE DEPARTED UPPER LOW. HIGHS ON SUNDAY COULD TOP OUT IN THE
MID TO UPPER 40S FOR MOST LOCATIONS...WITH A FEW READINGS AT OR
SLIGHTLY ABOVE 50 NORTH OF THE TENNESSEE BORDER AND ALONG AND SOUTH
OF THE HAL ROGERS PARKWAY. A WEAK RIDGE OF HIGH PRESSURE ALOFT WILL
BE THE WEATHER MAKER ACROSS THE REGION TO END THE WEEKEND.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 306 AM EST SAT DEC 20 2014

ACTIVE PATTERN STILL EXPECTED THROUGH CHRISTMAS WEEK. IN
FACT...FIRST SYSTEM WILL BE PUSHING NORTHEAST ALONG THE SPINE OF THE
APPALACHIANS TO START THE NEW WORK WEEK. NAM REMAINS THE MOST
AGGRESSIVE WITH THE NORTHWEST EXTENSION OF PRECIPITATION. STILL NOT
CONVINCED WE WILL OVERCOME THE DOWNSLOPING SOUTHEAST FLOW.
THUS...HAVE CUT BACK ON POPS INTO THE SLIGHT CHANCE CATEGORY. GFS
SEEMS TO BE CATCHING ONTO THE DOWNSLOPING THE BEST...ALTHOUGH THIS
MAY BE DUE TO THE FACT IT DOES NOT CONTAIN AS MANY SHALLOW LAYERS AS
THE NAM DOES. REGARDLESS...THE PATTERN DOES NOT SUPPORT MUCH
PRECIPITATION AND IT SHOULD BE A FAST MOVER WITH CHANCES MAINLY
DURING THE MORNING HOURS. ANY PRECIPITATION WILL REMAIN ALL RAIN AS
MILDER CONDITIONS SPREAD NORTHWARD WITH THE SYSTEM. BY MONDAY
AFTERNOON INTO TUESDAY...SOUTHEAST FLOW ONLY STRENGTHENS THROUGH
THIS PERIOD...LIKELY KEEPING THE AREA DRY. MUCH MILDER AIR WILL ALSO
SPREAD NORTHWARD. THIS WILL SET UP A FEW VERY MILD DAYS FOR MID TO
LATE DECEMBER WITH HIGHS IN THE 50S ON MONDAY AND AROUND 60 BY
TUESDAY. GUIDANCE IS HIGHER WITH TEMPERATURES INTO TUESDAY...BUT
OPTED TO STAY JUST UNDER THESE NUMBERS AS MID/HIGH CLOUDS COULD KEEP
TEMPERATURES DOWN SLIGHTLY.

BY TUESDAY NIGHT...A NORTHERN STREAM WAVE IS EXPECTED TO PHASE WITH
THE SOUTHERN STREAM WITH AN AREA OF LOW PRESSURE DEVELOPING ACROSS
THE LOWER MISSISSIPPI RIVER VALLEY. THIS SYSTEM WILL QUICKLY PUSH
NORTHWARD INTO THE GREAT LAKES BY MIDDAY WEDNESDAY...AS IT QUICKLY
DEEPENS. LATEST 00Z ECMWF HAS SLOWED EVERYTHING DOWN A BIT INTO THE
DAY WEDNESDAY...SO HAVE TRENDED TOWARDS A SLIGHTLY SLOWER EVOLUTION
WITH THE FORECAST. REGARDLESS...THIS SYSTEM WILL SEND A VERY STRONG
COLD FRONT ACROSS EASTERN KENTUCKY LATE TUESDAY NIGHT THROUGH
WEDNESDAY. STRONG FORCING WILL YIELD WIDESPREAD SHOWERS AS THE FRONT
PUSHES EAST. THE STRONG DYNAMICS ALONE COULD SUPPORT SOME THUNDER
LATE TUESDAY NIGHT INTO WEDNESDAY MORNING...BUT OPTED TO LEAVE IT
OUT FOR ONE MORE FORECAST CYCLE AND SEE IF MODELS MIGHT SHOW MORE
SUPPORT IN THE NEXT FEW RUNS. GOING TO BE QUITE WINDY AS WELL
WEDNESDAY INTO WEDNESDAY NIGHT AS THIS SYSTEM DEEPENS. SOME WIND
GUSTS UP TO 35 OR 40 MPH MAY BE POSSIBLE. STAYED ABOVE GUIDANCE FOR
LOWS TUESDAY NIGHT (AROUND 50) AS WE SHOULD STAY WELL MIXED AHEAD OF
SUCH A STRONG FRONT. HIGHS WEDNESDAY WILL LIKELY OCCUR EARLY AS THE
FRONT WILL BRING CRASHING TEMPERATURES THROUGH THE DAY WEDNESDAY. A
SECOND WAVE WILL PUSH EAST THROUGH THE AFTERNOON AND
EVENING...KEEPING PRECIPITATION GOING. THE COLD AIR WILL BRING A
TRANSITION OVER SNOW AS WE HEAD THROUGH WEDNESDAY AFTERNOON AND
EVENING. WHILE TEMPERATURES SHOULD STAY ABOVE FREEZING THROUGH EARLY
EVENING...IF SNOWFALL RATES CAN GET GOOD ENOUGH...WE COULD SEE A
LIGHT COATING BY LATE IN THE DAY IN SOME AREAS. ISOLATED TO
SCATTERED SNOW SHOWERS WILL LINGER INTO WEDNESDAY NIGHT...ALTHOUGH
MODELS ARE SHOWING A FASTER EXIT OF THE MOISTURE...SO THE WINDOW FOR
SNOW ACCUMULATIONS WILL NOT BE ALL THAT BIG. THUS...ANY ACCUMULATION
WILL REMAIN LIGHT...LIKELY UNDER AN INCH...EXCEPT FOR PERHAPS THE
HIGHER RIDGES WHERE AN EARLIER TRANSITION WILL BE POSSIBLE.

BY CHRISTMAS...RIDGING SPREADS BACK INTO THE AREA...SETTING UP A
QUITE CHRISTMAS DAY. TEMPERATURES WILL BE COOLER WITH HIGHS ONLY
INTO THE LOW 40S. OUR NEXT WEATHER SYSTEM WILL TAKE SHAPE BY
FRIDAY...BUT THE TRACK IS EXPECTED TO REMAIN WELL NORTHWEST OF
KENTUCKY AT THIS TIME...WHICH WILL KEEP PRECIPITATION FRIDAY NIGHT
INTO SATURDAY WITH AN ADVANCING COLD FRONT ALL IN THE FORM OF RAIN.
THIS WILL ALSO MEAN MILDER WEATHER RETURNS FROM FRIDAY INTO
SATURDAY...BEFORE A RETURN TO COLDER WEATHER BY NEXT SUNDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 106 AM EST SAT DEC 20 2014

TAF FORECAST REMAINS A CHALLENGE IN REGARDS TO PRECIPITATION ONSET
NEAR LOZ AND SME AND THE NORTHWARD EXTENT OF ANY PRECIP THAT DOES
FORM. BASED ON SURROUNDING OBS AND THE LATEST MODEL DATA...IT APPEARS
THAT MVFR CONDITIONS WILL THE WORST WE SEE AT ANY OF THE TAF SITES
OVERNIGHT AND THROUGH THE DAY ON SATURDAY.


&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...AR
LONG TERM...KAS
AVIATION...AR






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