Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 311620
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1120 AM EST SAT JAN 31 2015

.UPDATE...
ISSUED AT 1120 AM EST SAT JAN 31 2015

FRESHENED UP THE HOURLY TEMPERATURES...DEW POINTS...AND SKY COVER
OVER THE NEXT FEW HOURS BASED ON THE CURRENT TRENDS IN OBSERVATIONS.
OTHERWISE...THE FORECAST REMAINS ON TRACK. STILL WAITING ON THE
NEWEST MODEL RUNS BEFORE ANY UPDATES ARE MADE CONCERNING THE
PRECIP/WINTER WEATHER THAT IS INCOMING OVERNIGHT. OTHERWISE...CLOUDS
ARE ON TRACK TO CONTINUE MOVING INTO THE REGION FROM THE WEST
THROUGHOUT THE AFTERNOON. A FEW LIGHT RETURNS ARE ACTUALLY SHOWING UP
ON NEIGHBORING RADARS WHERE BKN/OVC CLOUD COVER HAS TAKEN HOLD...BUT
GIVEN THE AMOUNT OF LOW LEVEL DRY AIR...IT IS UNLIKELY THAT ANY OF
THESE RETURNS WILL MAKE IT TO THE GROUND. DEW POINT DEPRESSION ARE
STILL AROUND 8 OR MORE DEGREES IN THE AREAS WHERE THESE RETURNS ARE
SHOWING UP. AS A RESULT...WILL NOT CHANGE POPS TO INCLUDE MENTION OF
PRECIP AT THIS TIME UNLESS EVIDENCE STARTS TO SUPPORT OTHERWISE.

UPDATE ISSUED AT 752 AM EST SAT JAN 31 2015

FRESHENED UP THE HOURLY TEMPERATURES...DEW POINTS...AND SKY COVER
OVER THE NEXT FEW HOURS BASED ON THE CURRENT TRENDS IN OBSERVATIONS.
OTHERWISE...THE FORECAST REMAINS ON TRACK.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 359 AM EST SAT JAN 31 2015

SURFACE HIGH PRESSURE IS CURRENTLY SPRAWLED ACROSS THE MISSISSIPPI
VALLEY...WITH DEEP LOW PRESSURE NEARING NOVA SCOTIA. ALOFT...A SPLIT
FLOW REGIME IS CURRENTLY IN PLACE. A DEEP TROUGH IS POSITIONED IN
THE WESTERN ATLANTIC...WITH NORTHWEST FLOW ALIGNED FROM THE OHIO
VALLEY BACK TO THE CONTINENTAL DIVIDE WITHIN THE NORTHERN STREAM. IN
THE SOUTHERN STREAM...RIDGING RESIDES ACROSS THE SOUTHERN
PLAINS...WITH A CUTOFF LOW SPIRALING OVER THE DESERT SOUTHWEST.

A COLD NIGHT IS ON TAP FOR EASTERN KENTUCKY WITH CLEAR SKIES AND CALM
WINDS THANKS TO NEARBY HIGH PRESSURE. TEMPERATURES ARE CURRENTLY
RUNNING AS COLD AS THE MIDDLE TEENS IN THE MORE SHELTERED
VALLEYS...WITH RIDGETOPS AROUND 20.

THE NORTHERN STREAM WILL CONTINUE TO BE THE DOMINANT PLAYER IN OUR
WEATHER THROUGH THE SHORT TERM...AS A SHORT WAVE TROUGH CURRENTLY
MOVING SOUTHEAST ACROSS ALBERTA WILL DROP SOUTHEAST AND DIG ACROSS
THE PLAINS AND EVENTUALLY INTO THE OHIO VALLEY THROUGH THE END OF THE
PERIOD. THIS WILL ALLOW FOR DEVELOPING SURFACE LOW PRESSURE TO MOVE
EAST INTO THE LOWER OHIO VALLEY...BRINGING WIDESPREAD PRECIPITATION
TO THE AREA BY LATE SUNDAY.

TODAY WILL FEATURE A MOSTLY SUNNY START TO THE DAY...BEFORE MID AND
HIGH LEVEL CLOUDS ARE ON THE INCREASE THIS AFTERNOON. DESPITE THE
COLD START...TEMPERATURES SHOULD RECOVER TO THE 40S FOR MOST
LOCATIONS. CLOUDS WILL CONTINUE TO THICKEN AND LOWER TONIGHT. AS
ISENTROPIC LIFT ENSUES OUT AHEAD OF THE DEVELOPING LOW PRESSURE
SYSTEM OFF TO THE WEST...SOME LIGHT PRECIPITATION IS POSSIBLE LATE
TONIGHT INTO SUNDAY MORNING.

THE GENERAL MODEL TREND HAS BEEN FOR A FURTHER NORTHWARD TRACK OF THE
SURFACE LOW. A WARM NOSE AT AROUND 925 MB...RUNNING ANYWHERE FROM 4
TO 6C WILL ADVECT INTO THE AREA OVERNIGHT TONIGHT INTO EARLY SUNDAY
MORNING. ANY LIGHT PRECIPITATION WILL START OUT AS A SNOW/SLEET
MIXTURE...BEFORE LIKELY GOING OVER TO MAINLY LIQUID TOWARDS DAWN
SUNDAY MORNING. AM A LITTLE CONCERNED THAT INTERIOR VALLEYS WILL
LIKELY DECOUPLE SATURDAY EVENING...DROPPING OFF INTO THE MID AND
UPPER 20S AND LIKELY NOT MODIFYING MUCH UNTIL THE MID TO LATE MORNING
ON SUNDAY. AS SUCH...HAVE INCLUDED FREEZING RAIN AS A POSSIBILITY.
ONCE THE SURFACE LOW DRAWS CLOSER DURING THE DAY...TEMPERATURES WILL
WARM UP INTO THE 45 TO 50 DEGREE RANGE...WITH WIDESPREAD RAINS MOVING
IN FROM WEST TO EAST SUNDAY AFTERNOON.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 359 AM EST SAT JAN 31 2015

THE EXTENDED FORECAST PERIOD BEGINS WITH AN ACTIVE AND PROGRESSIVE
UPPER LEVEL PATTERN IN PLACE. SUNDAY NIGHT...A POTENT SHORTWAVE
CONTINUES TO PROGRESS THROUGH THE OH VALLEY AND THE MID ATLANTIC
STATES. MODELS CONTINUE TO SHOW NO ISSUES IN AGREEMENT WITH THE WAVE
EXITING THE EAST COAST AS A 120 KNOT JET STREAK HEADING UP THE EAST
COAST ALL THE TROUGH TO LIFT NORTHEAST INTO THE NORTHEAST AND EXIT
OFF THE COAST BY TUESDAY 00Z. THE SURFACE LOW TRACK SEEMS TO BE SET
TO MOVE ALONG AND JUST NORTH OF THE OH RIVER WITH A GOOD CONSENSUS
OF THE MODELS SHOWING THIS NOW. FRONTAL PASSAGE SEEMS TO BE JUST
AFTER 00Z MONDAY WITH COLD AIR ADVECTION THEN BEGINNING IN EARNEST
AND A CHANGE OVER TO SNOW THROUGH THE NIGHT. HOWEVER...A GOOD
PORTION OF THE DEPTH OF THE MOISTURE EXITS QUITE EARLY BEFORE THE
COLDER AIR ARRIVES BEHIND THE FRONT. WITH THIS WOULD EXPECT A LESSER
PERIOD OF SNOW BUT AN UPSLOPE COMPONENT TO THE WINDS WILL SET UP FOR
THE DAY ON MONDAY. BECAUSE OF THIS...WOULD EXPECT SOME VERY LIGHT
SNOW ACCUMULATIONS WITH THE MOST IN THE HIGHER ELEVATIONS. IN
FACT...DESPITE THE SHALLOW MOISTURE...STILL SOME GOOD LIFT WILL
REMAIN IN THE LOWER LEVELS WITH THE UPSLOPE FLOW THAT SNOW SHOWERS
WILL LINGER INTO THE DAY ON MONDAY WITH LESS THAN AN INCH LIKELY IN
THE VALLEYS BUT UP TO TWO INCHES POSSIBLE ABOVE 2000 FEET.

IN A CONTINUED PROGRESSIVE UPPER LEVEL FLOW...A PASSING SHORT WAVE
RIDGE WILL PROVIDE A DAYS BREAK FROM WEATHER BEFORE THE NEXT WAVE
MOVES IN ON WEDNESDAY. HERE IS WHERE THE GFS AND EURO DIVERGE
GREATLY. THE GFS BRINGS A DEVELOPING CLOSED LOW ACROSS THE SOUTH
WITH THE AFOREMENTIONED WAVE MOVING INTO THE OH VALLEY ON WEDNESDAY
AND CREATING A PHASING SCENARIO WITH THE POSSIBILITY OF HEAVY
PRECIP OVER SOUTHEASTERN KENTUCKY AS A STRONG SURFACE LOW DEVELOPS
ON THE LEE SIDE OF THE APPALACHIANS AND FINALLY MOVES EAST OFF THE
COAST. BUT THE EURO KEEPS THE LOW TO THE SOUTH AND EXITS OFF THE
SOUTHEASTERN COAST WHILE THE WAVE ALONG THE NORTHERN PORTION OF THE
JET ONLY DRAGS A WEAK FRONT ACROSS THE AREA. THE MODEL ALL BLEND
GOES BETWEEN THESE TWO SCENARIOS AND ONLY GIVES CHANCE POPS OVER THE
AREA. THOUGH THE FRONT MOVING IN FROM THE NORTHWEST LOOKS PRETTY
DRY...WILL LEAN TOWARDS THE MODEL ALL BLEND SOLUTION FOR CHANCE POPS
ON WEDNESDAY THROUGH FRIDAY. THE TREND OF THE EURO AND GFS LEAVE
LITTLE ROOM FOR CONFIDENCE DUE TO INCONSISTENCIES AND LACK OF
AGREEMENT. WILL HAVE TO WATCH FOR TRENDS IN THE MODELS TO SEE IF
THIS SET UP WILL POSE A THREAT. AS OF RIGHT NOW...THIS ONLY GETS A
MENTION OF SNOW IN THE HWO.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 752 AM EST SAT JAN 31 2015

VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD...ALTHOUGH MID AND
HIGH LEVEL CLOUDS WILL BE ON THE INCREASE THIS AFTERNOON AND EVENING
OUT AHEAD OF THE NEXT APPROACHING WEATHER SYSTEM. CEILINGS WILL LOWER
TO BETWEEN 5 AND 8K FEET AGL BETWEEN 06 AND 12Z...WITH AT LEAST A
SMALL THREAT OF SOME WINTRY PRECIPITATION. WINDS WILL AVERAGE LESS
THAN 5 KTS.


&&

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

$$

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





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