Area Forecast Discussion
Issued by NWS Jackson, KY

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632
FXUS63 KJKL 140420
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1120 PM EST SAT FEB 13 2016

.UPDATE...
ISSUED AT 1120 PM EST SAT FEB 13 2016

WITH THE 00Z MODEL RUNS COMING IN THIS EVENING...HAVE UPDATED THE
FORECAST WITH THE LATEST DATA. WARMER AIR MOVING IN A BIT QUICKER
SUNDAY NIGHT WILL CHANGE THE SNOW OVER TO RAIN A BIT QUICKER. SO
HAVE UPDATED THE FORECAST TO INPUT A NONDIURNAL TREND INTO THE
FORECAST SUNDAY NIGHT. THIS DOES IMPACT SNOW TOTALS A BIT BUT
STILL EXPECTING THE 3 TO 5 INCHES OVER A GREATER THAN 12 HOUR
PERIOD. HOWEVER...THE MOST RECENT RUNS OF THE GFS AND NAM HAVE
HINTED AT A BAND DEVELOPING BETWEEN THE MOUNTAIN AND HAL ROGERS
PARKWAYS. INTENSIFICATION OF THIS AREA MAY BE ENOUGH TO PUT DOWN A
SIGNIFICANT AMOUNT OF SNOW BEFORE THE PRECIP CHANGES OVER TO RAIN.
THE OTHER CONCEPT IS THE HIGHER TERRAIN TO THE SOUTHEAST WHERE
TEMPS WILL BE LOW ENOUGH FOR A LATER CHANGE OVER TO SNOW BUT
TAKING THE BANDED PRECIP LONGER TO DEVELOP THERE. THE UNCERTAINTY
OF TWO FACTORS MAKE CONFIDENCE LOW ENOUGH TO CONTINUE WITH THE
ADVISORY. A NEW ZFP HAS BEEN SENT OUT WITH THIS UPDATE.

UPDATE ISSUED AT 700 PM EST SAT FEB 13 2016

ISSUED AN UPDATE TO FRESHEN UP THE HOURLY TEMPERATURES AND DEW
POINTS AND ADJUST THE HOURLY TEMPERATURE TREND. TEMPS ARE A BIT
SLOW TO DROP THIS EVENING BUT AS THE NEXT FEW HOURS PASS...MOST
TEMPS WILL BEGIN TO DROP OFF A FEW DEGREES PER HOUR. THE UPDATED
GRIDS HAVE BEEN SENT TO NDFD AND WEB SERVERS.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 342 PM EST SAT FEB 13 2016

AS HIGH PRESSURE MOVED INTO THE REGION FROM THE NW TODAY...MUCH OF
EASTERN KY EXPERIENCED NW FLOW...ENHANCED IN THE MID AND UPPER
LEVELS BY A STRONG UPPER LEVEL TROUGHING PATTERN. THIS NW FLOW
ALLOWED MOISTURE FROM LAKE MICHIGAN TO FLOW AS FAR SOUTH AS EASTERN
KY...AND RESULTED IN SCATTERED PATCHES OF SNOW FLURRIES THROUGHOUT
THE DAY...ESPECIALLY ACROSS THE NORTHERN AND FAR EASTERN CWA. AS
HIGH PRESSURE SETTLES IN CLOSER TO THE REGION THIS AFTERNOON...WINDS
WILL CONTINUE TO LIGHTEN AND PREVENT BEST MOISTURE FROM PROTRUDING
SO FAR SOUTHWARD INTO THE OHIO VALLEY...CUTTING OFF ANY FURTHER
FLURRY ACTIVITY. OTHERWISE...WITH HIGH PRESSURE PASSING OVERHEAD
OVERNIGHT...THE MAIN ELEMENT OF CONCERN WILL BE TEMPERATURES.

STRONG NW TO SE FLOW IN THE MID AND UPPER LEVELS WILL CONTINUE TO
PULL DRIER BUT MUCH COLDER ARCTIC AIR INTO THE REGION. WITH MOSTLY
CLEAR TO PARTLY CLOUDY SKIES EXPECTED THROUGH THE FIRST PART OF THE
NIGHT...STRONG SUBSIDENCE WILL FORM...AND MAXIMUM RADIATIONAL
COOLING WILL ENSUE. IT IS LIKELY THAT MANY OF THE DEEPER VALLEYS
WILL SEE SINGLE DIGIT TEMPERATURES BY DAWN ON SUNDAY...WHILE MOST OF
THE RIDGES WILL BE LUCKY TO SEE THE TEENS. THIS COUPLED WITH LIGHT
WINDS COULD RESULT IN WIND CHILLS AROUND 0 OR EVEN SEVERAL DEGREES
BELOW IN SOME LOCATIONS.

BEHIND THE EXITING HIGH PRESSURE ON SUNDAY...WINDS WILL BECOME MORE
SOUTHERLY...WITH TEMPERATURES RISING BACK INTO THE MID 20S TO LOW
30S. MEANWHILE...AN UPPER LEVEL WAVE WILL BEGIN STRENGTHENING ACROSS
THE UPPER MIDWEST...MOVING EASTWARD TOWARDS THE MISSISSIPPI RIVER
VALLEY DURING THE DAY. VEERING SURFACE WINDS IN WAKE OF THE
DEPARTING RIDGE WILL USHER IN WARMER AIR ALOFT LATER TONIGHT INTO
SUNDAY. THIS WILL HELP DRAW A STREAM OF GULF MOISTURE NORTH AHEAD OF
THIS UPPER DISTURBANCE. TOP-DOWN MOISTENING WILL LEAD TO INCREASING
HIGH-MID CLOUD COVER FROM LATE TONIGHT THROUGH THE DAY
SUNDAY...BEFORE LOW CLOUDS AND RESULTING SNOW COMMENCES SUNDAY
AFTERNOON.

AS TEMPERATURES FALL SEVERAL DEGREES SUNDAY NIGHT...WE CAN PRETTY
MUCH ENSURE THAT ALL PRECIPITATION BETWEEN SUNDAY AFTERNOON AND
MONDAY MORNING WILL FALL IN THE FORM OF SNOW. THE NAM CONTINUES TO
BE THE MOST AGGRESSIVE ON TIMING...AND THE OUTLIER AS SUCH...SO
TRENDED MORE TOWARDS A ECMWF AND GFS SOLUTION FOR BOTH TIMING AND
SNOW RATIOS. GENERALLY AGREED WITH WPC QPF GUIDANCE...WHICH WHEN
PAIRED WITH FORECASTED SNOW RATIOS...RESULTED IN TOTAL SNOWFALL
ACROSS THE REGION BETWEEN SUNDAY AFTERNOON AND MONDAY MORNING IN THE
2.5 TO 4.5 RANGE. DUE TO THE ELONGATED NEARLY 24 HOUR TIME PERIOD OF
SNOW...THIS ONLY FALLS INTO ADVISORY CRITERIA. AFTER SOME GOOD
COLLABORATION WITH NEIGHBORING OFFICES...WE DECIDED TO HOIST OUR
ADVISORY WITH A START TIME OF 18Z SUNDAY...AND ENDING 15Z MONDAY.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 350 PM EST SAT FEB 13 2016

WAVE RESPONSIBLE FOR THE SYSTEM ON MONDAY HAS JUST MOVED ONSHORE
AND SHOULD BE SAMPLED BETTER BY OUR UPPER AIR NETWORK THIS EVENING
FOR THE 00Z MODELS. IN THE MEANTIME...WE ARE STILL DEALING WITH
SOME MODEL DISCREPANCIES...AND WILL STAY CLOSE TO A BLENDED
APPROACH AS POSSIBLE TO HEDGE FROM THE VARIOUS SOLUTIONS. AS IT
STANDS NOW...LOOKS LIKE A SNOW SHOULD TRANSITION OVER TO RAIN
MONDAY MORNING AS A SOMEWHAT DEEP WEDGE OF WARM AIR SPREADS
NORTHWARD MONDAY MORNING ACROSS EASTERN KENTUCKY. WHERE THE MODELS
DIFFER, IS HOW WRAPPED UP THE SYSTEM GETS AND THUS HOW FAR NORTH
THE WARM AIR CAN MAKE IT. FOR NOW...OPTING TO GO WITH THE RAIN FOR
MUCH OF THE DAY MONDAY. IT DOES APPEAR AS MOISTURE PULLS OUT
MONDAY NIGHT...WE MAY SEE SNOW MIX BACK IN OR COMPLETELY CHANGE
BACK OVER. HOWEVER...MODELS ARE SUGGESTING A FASTER END TO THE
PRECIPITATION MONDAY NIGHT...SO ANY ACCUMULATIONS MAY BE MORE
LIMITED. THE BRIEF LULL WILL BE SHORT INTO TUESDAY AS ANOTHER
CLIPPER DIVES SOUTH ACROSS THE AREA. RIGHT NOW...MODELS ARE
FAVORING A MORE NORTHERN TRACK...WHICH WOULD KEEP ALL
PRECIPITATION PRIMARILY RAIN AT THE ONSET TUESDAY
AFTERNOON/EVENING. AS THE SYSTEM PASSES BY...COLD AIR WILL SPREAD
BACK IN AND WE MAY SEE A CHANGEOVER TO SNOW WITH SOME VERY LIGHT
ACCUMULATIONS POSSIBLE. MUCH LIKE THE PAST FEW SYSTEMS...LIGHT
FLURRIES/SNOW SHOWERS COULD LINGER WELL INTO WEDNESDAY BEFORE
DISSIPATING. FINALLY WE SHOULD DRY OUT HEADING INTO THURSDAY AND
FRIDAY AS HEIGHTS START TO BUILD OVER THE REGION. THIS WILL YIELD
A MORE SIGNIFICANT WARM UP AS WE HEAD INTO THE LATE WEEK PERIOD.
ANOTHER SYSTEM MAY PUSH ACROSS THE AREA LATE FRIDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 700 PM EST SAT FEB 13 2016

EXPECT VFR CONDITIONS THROUGH TONIGHT AS HIGH PRESSURE SLOWLY
MOVES THROUGH THE AREA TONIGHT. UPPER LEVEL CLOUD COVER WILL BE ON
THE INCREASE AHEAD OF THE NEXT SYSTEM MOVING INTO EASTERN
KENTUCKY. MID AND LOW LEVEL CLOUD COVER WILL BEGIN TO MOVE INTO
THE AREA BY MIDDAY WITH MVFR AND BELOW CONDITIONS EXPECTED.
SNOWFALL WILL DROP VIS DOWN TO 2 MILES AT MOST LOCATIONS. EXPECT
IFR THROUGH THE END OF THE PERIOD. WINDS WILL BE LIGHT THROUGH
MUCH OF THE PERIOD.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 1 PM SUNDAY TO 10 AM EST MONDAY FOR
KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.

&&

$$

UPDATE...SHALLENBERGER
SHORT TERM...JMW
LONG TERM...KAS
AVIATION...SHALLENBERGER



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