Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 162357
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
757 PM EDT TUE SEP 16 2014

.UPDATE...
ISSUED AT 713 PM EDT TUE SEP 16 2014

FORECAST IS IN GOOD SHAPE. TWEAKED GRIDS TO HOURLY OBSERVATIONS.
STILL SEEING SOME VERY LIGHT ECHOS ACROSS THE SOUTHEAST. THEREFORE
WILL HOLD OFF ON ANY UPDATE TO THE ZFP FOR A BIT LONGER BEFORE
REMOVING LIGHT SPRINKLE ACTIVITY. REGIONAL SATELLITE IS SHOWING DECENT
AMOUNT OF CLOUD EROSION AS DRY AIR FROM DEVELOPING SUBSIDENCE
INVERSION ALOFT MIXES INTO THE TOP OF THE BOUNDARY LAYER. RELATIVELY
HIGH SFC DEW POINTS REMAIN HOWEVER. CONCERN IS THAT WITH STRONG
SUBSIDENCE AND THEREFORE DRYING TAKING PLACE JUST ABOVE THE BOUNDARY
LAYER...RADIATIVE COOLING WILL BE THE CATALYST FOR LOW STRATUS AND
FOG TO REDEVELOP OVERNIGHT. WILL KEEP A CLOSE EYE ON OBSERVATIONS
THROUGH THE EVENING IN CASE A HEADLINE IS NEEDED.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 350 PM EDT TUE SEP 16 2014

19Z SFC ANALYSIS SHOWS A SLOW MOVING COLD FRONT EXITING FAR SOUTHEAST
KENTUCKY AS A COOL AND DRY AREA OF HIGH PRESSURE PUSHES DEEPER INTO
THE OHIO VALLEY. BEHIND THIS BOUNDARY...A FEW LIGHT SHOWERS AND
PLENTY OF SPRINKLES/DRIZZLE REMAIN OVER A GOOD PORTION OF THE CWA.
ON SATELLITE...THE LOW CLOUDS ARE BREAKING UP OVER THE SOUTHERN
PORTION OF EAST KENTUCKY WHILE THEY ARE HOLDING TIGHT OVER JKL AND
POINTS NORTH. THE EXTENSIVE CLOUD COVER AND POCKETS OF LIGHT PCPN
KEPT TEMPERATURES WELL BELOW NORMAL FOR THE DAY WITH READINGS
CURRENTLY RANGING FROM A CHILLY 60 DEGREES ALONG AND NORTH OF
INTERSTATE 64 WHILE SOME 70 DEGREE READINGS HAVE SHOWN UP TO THE
SOUTH THANKS TO PARTIAL SUNSHINE. DEW POINTS VARY FROM THE MID 50S
NORTH TO THE LOWER AND MIDDLE 60S SOUTH. LIGHT NORTH WINDS ARE ADDING
TO THE CHILL THROUGH MOST OF THE AREA.

THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH EAST KENTUCKY STILL IN
THE GRIP OF A BROAD AND UNSEASONABLY DEEP TROUGH THROUGH THE EASTERN
HALF OF THE NATION. FAIRLY FAST NORTHWEST FLOW AT THE BASE OF THIS
TROUGH WILL KEEP A SERIES OF WEAK DISTURBANCES MOVING THROUGH EAST
KENTUCKY DURING THE SHORT TERM PORTION OF THE FORECAST. THE
HEALTHIEST OF THESE ACTUALLY PASSES THROUGH DURING THE DAY WEDNESDAY
WITH A KINK IN THE FLOW LINES. GIVEN THE MODEL SIMILARITIES ALOFT
HAVE GONE WITH A GENERAL BLEND WHILE FAVORING THE HRRR AND NAM12
THROUGH THE FIRST 18 TO 24 HOURS.

SENSIBLE WEATHER WILL FEATURE THE LINGERING SHOWERS AND POCKETS OF
SPRINKLES/DRIZZLE DRYING UP BY EARLY EVENING WITH SOME CLEARING
EXPECTED FOR A TIME. HOWEVER...THIS CLEARING...WITH LITTLE IN THE
WAY OF SFC WINDS...WILL LIKELY ALLOW AREAS OF DENSE FOG AND LOW
STRATUS TO DEVELOP...RESTRICTING VISIBILITY IN MOST PLACES ACROSS
EAST KENTUCKY BY DAWN. HAVE HIT THIS HARD IN THE GRIDS AND ALSO THE
HWO. WILL LEAVE IT TO LATER SHIFTS TO MONITOR THE CLEARING...
ADVECTION...AND PRELIMINARY FOG PRODUCTION FOR A POTENTIAL ADVISORY
OR SPS. ONCE THE FOG BURNS OFF ON WEDNESDAY MORNING SOME SUNSHINE CAN
BE EXPECTED... BUT THE UPPER LEVEL ENERGY WILL LIKELY BRING IN MORE
LOW AND MID LEVEL CLOUDS. IN FACT...CANNOT COMPLETELY RULE OUT SOME
MORE SPRINKLES OR A LIGHT SHOWER AS THIS WAVE MOVES BY ALOFT
WEDNESDAY AFTERNOON. FOR NOW...THOUGH...HAVE KEPT THE POPS JUST BELOW
MENTIONING. THE WAKE OF THIS WILL SET UP ANOTHER NIGHT OF AT LEAST
PARTIAL CLEARING ALONG WITH AREAS OF FOG...LOCALLY DENSE FORMING LATE
AT NIGHT. THIS SHOULD BE THE COLDER OF THE NIGHTS WITH SOME UPPER 40S
POSSIBLE IN THE VALLEYS THROUGH THE NORTHERN HALF OF THE AREA...AND
ELSEWHERE IF THE CLEARING AND FOG ALLOW IT.

AGAIN USED THE CONSSHORT AS A STARTING POINT FOR THE T/TD/WIND GRIDS
THROUGH THE FIRST 24 HOURS BEFORE LOADING THE SUPER BLEND THEREAFTER.
DID NUDGE THE LOWS TONIGHT AND ESPECIALLY WEDNESDAY NIGHT FOR RIDGE
AND VALLEY DIFFERENCES. AS FOR POPS...ENDED UP HIGHER THAN MOS IN THE
NEAR TERM AND ALSO FOR LATER WEDNESDAY...OTHERWISE KEPT THE POPS LOW
SIMILAR TO THE GUIDANCE.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 259 PM EDT TUE SEP 16 2014

THURSDAY MORNING STARTS THE EXTENDED PERIOD WITH AN AMPLIFIED UPPER
LEVEL PATTERN. STRONG TROUGHING WILL EXIST ACROSS MUCH OF THE
EASTERN THIRD OF THE CONUS...WHILE HIGH PRESSURE RIDGING REMAINS
PARKED ACROSS THE SOUTHWESTERN STATES. THIS PATTERN WILL REMAIN IN
PLACE THROUGH FRIDAY...BEFORE IT STARTS TO BREAK DOWN AND HEIGHTS
BEGIN TO BUILD ACROSS EASTERN KY INTO THE DAY SATURDAY. N/NW WINDS
WILL USHER IN COLD WINDS DURING THE DAY THURSDAY...WITH HIGHS ONLY
REACHING THE LOW TO MID 70S. THIS WILL NOT
CONTINUE...HOWEVER...AS A SHORTWAVE MOVES TOWARDS THE REGION DURING
THE DAY FRIDAY. AT THE SURFACE...A POTENT COLD FRONT WILL BE MAKING
ITS WAY FROM THE NORTHERN PLAINS TOWARDS KY...WITH SRLY WINDS
PULLING UP WARM AIR OUT AHEAD OF THE FRONT. THIS WILL RESULT IN
INCREASING TEMPERATURES FRIDAY...REACHING MORE SEASONABLE UPPER 70S
AND LOW 80S FOR BOTH FRIDAY AND SATURDAY.

THE FRONT WILL LOSE STRENGTH AS IT MOVES TOWARDS THE EASTERN KY
REGION AS UPPER LEVEL HEIGHTS CONTINUE TO BUILD INTO THE WEEKEND. BY
THE TIME THE SYSTEM REACHES EASTERN KY...THERE WILL BE VERY LITTLE
INSTABILITY LEFT...AS WELL AS VERY LITTLE CONCERN FOR PWAT VALUES.
MODELS ARE STILL SLIGHTLY DIFFERENT ON THE EXACT TIMING AND EXTENT
OF THE PRECIPITATION...SO WILL CONTINUE TO STICK CLOSE TO A MODEL
BLEND. AS SUCH...EXPECT THE PRECIP TO MOVE AHEAD OF THE FRONT AND
INTO EASTERN KY BETWEEN 12 AND 18Z SUNDAY...AND CONTINUE INTO EARLY
AFTERNOON MONDAY. DESPITE LACK OF INSTABILITY...NEIGHBORING OFFICES
CONTINUE TO FAVOR THE FACT THAT THE FRONTAL BOUNDARY LIFT ALONE MAY
BE ENOUGH TO INITIATE SOME THUNDER. AS SUCH...KEPT IN ONLY SLIGHT
MENTION OF THUNDER AS THE LINE MAKES IT THROUGH KY SUNDAY INTO
MONDAY...WITH THE EXCEPTION OF SUNDAY AFTERNOON...WHERE IT SEEMS THE
INCOMING FRONT WILL BRING A BRIEF PERIOD OF HEIGHTENED INSTABILITY
WITH AFTERNOON HEATING...AND THEREFORE CHANCES WERE INCLUDED.

TEMPS WILL COOL SUBSTANTIALLY BEHIND THE FRONTAL PASSAGE BY DURING
THE DAY MONDAY. UPPER LEVEL RIDGING WILL SLOWLY MOVE IN OVERHEAD
INTO THE DAY TUESDAY...WHILE AT THE SURFACE BROAD HIGH PRESSURE
TAKES CONTROL. SURFACE WINDS WILL BECOME MORE NORTHERLY...AS STRONG
W/NW WINDS ALOFT. THIS WILL RESULT IN THE RETURN OF ANOTHER
UNSEASONABLY COOL AIR MASS AND HIGH TEMPERATURES ONLY TOPPING OUT IN
THE LOW TO MID 70S. TEMPS WILL CONTINUE TO DETERIORATE BY THE DAY
TUESDAY...WITH HIGHS IN THE UPPER 60S TO AROUND 70S EXPECTED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 757 PM EDT TUE SEP 16 2014

SOME IMPROVEMENT TO FLIGHT CONDITIONS THROUGH THE LATE AFTERNOON
HOURS...BUT EXPECT A RETURN TO LIFR CONDITIONS THROUGH THE OVERNIGHT
AS LOW STRATUS AND FOG REDEVELOPS ACROSS THE AREA. STAYED CLOSE TO
MODEL GUIDANCE...BRINGING ALL TAF SITES DOWN INTO MVFR TERRITORY
LATE THIS EVENING AND THEN TO LIFR LEVELS AFTER MIDNIGHT. WE SHOULD
SEE A GRADUAL IMPROVEMENT INTO THE DAY WEDNESDAY. WINDS THROUGH THE
PERIOD WILL BE GENERALLY LIGHT BUT PICK UP SOME...AROUND 5 KTS FROM
THE NORTH....NORTHWEST WEDNESDAY AFTERNOON.

&&

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

&&

$$

UPDATE...RAY
SHORT TERM...GREIF
LONG TERM...JMW
AVIATION...RAY





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