Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 231754
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
154 PM EDT TUE SEP 23 2014

.UPDATE...
ISSUED AT 1120 AM EDT TUE SEP 23 2014

UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. THE STRATUS IN THE FAR EASTERN PORTION OF EASTERN KENTUCKY
HAS BEEN VERY STUBBORN TO BURN OFF...BUT IS FINALLY SHOWING SIGNS OF
DOING SO. EXPECT THIS TO CONTINUE OVER THE NEXT HOUR. REDUCED THE
EXPECTED HIGH TEMPERATURES IN THE FAR EAST DUE TO THE CLOUDY COVER.
ALSO HAD TO MAKE SOME ADJUSTMENTS TO THE DEWPOINTS AS THEY WERE
HIGHER THAN WHAT WAS PREVIOUSLY FORECAST. THE REST OF THE FORECAST IS
ON TRACK.

UPDATE ISSUED AT 654 AM EDT TUE SEP 23 2014

FOG CONTINUES ACROSS MUCH OF FAR EASTERN KY...AS WELL AS IN MANY OF
THE RIVER VALLEYS ELSEWHERE. EXPECT THIS FOG TO BEGIN LIFTING AND
BURNING OFF OVER THE NEXT COUPLE OF HOURS AS DAYTIME HEATING ENSUES.
FORECAST SOUNDINGS OVER THE LAST 24 HOURS HAD POINTED AT VERY LOW DEW
POINTS BEING ABLE TO MIX DOWN TO SOME OF THE HIGHER ELEVATIONS JUST
BEFORE DAYBREAK /NAMELY BLACK MOUNTAIN/. HAD TRENDED THE LATEST
FORECAST PACKAGES DEW POINTS BACK UP SLIGHTLY BASED ON THE LATEST
MODEL DATA...BUT SO FAR THE DRY AIR INTRUSION HAS STAYED JUST
SLIGHTLY ABOVE THE FORECASTED HEIGHT...AND THEREFORE HAS NOT
MATERIALIZED ACROSS THE HIGHEST TERRAIN IN THE SE. OTHERWISE...THE
MAIN CONCERN THIS MORNING HAS BEEN KEEPING UP WITH THE TEMPERATURES
ACROSS THE CWA. LOADED IN THE LATEST OBSERVATIONAL DATA TO MAKE SURE
THE NEAR TERM FORECAST IS MATCHING UP WITH THE CURRENT CONDITIONS.
WARMING CONDITIONS SHOULD TAKE OVER FROM THIS POINT AS THE SUN
STARTS RISING...WITH RELATIVELY QUIET CONDITIONS EXPECTED THROUGHOUT
THE REMAINDER OF THE DAY.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 346 AM EDT TUE SEP 23 2014

FORECAST HAS CHANGED LITTLE FROM PREVIOUS FORECAST PACKAGE. STRONG
UPPER LEVEL RIDGING...COINCIDING WITH STRONG SURFACE HIGH
PRESSURE...WILL CONTINUE TO BE THE MAIN WEATHER DRIVER OVER THE
SHORT TERM PERIOD /TODAY THROUGH TOMORROW/. UPPER LEVEL PRESSURE
GRADIENTS WILL LESSON TODAY COMPARED TO YESTERDAY...AND WE WILL ALSO
LOSE THE INFLUENCE OF THE NORTHERN JET ACROSS THE REGION. AS
SUCH...TEMPERATURES WILL MODIFY SLIGHTLY WARMER...WHILE STILL
REMAINING QUITE BELOW SEASONABLE NORMALS. HIGHS TODAY SHOULD REACH
THE LOW 70S ACROSS MUCH OF THE REGION UNDER SUNNY SKIES AND LIGHT NE
WINDS. DEW POINTS WILL BE VERY LOW ACROSS THE REGION...WITH SOME OF
THE HIGHEST ELEVATIONS DIPPING INTO THE 20 DEGREE RANGE THROUGH THIS
MORNING.

KEPT MENTION OF VALLEY FOG IN FOR TONIGHT...AS WEATHER PATTERN WILL
BE SIMILAR TO THAT OF LAST NIGHT. STRONG SUBSIDENCE WILL TRAP
MOISTURE IN THE VALLEYS AND NEAR BODIES OF WATER...WHILE
TEMPERATURES QUICKLY DROP OFF UNDER THE INFLUENCE OF STRONG
RADIATIONAL COOLING. OVERNIGHT LOWS SHOULD BE A COUPLE DEGREES
WARMER THAN THIS MORNING...BUT ONCE AGAIN...STILL WELL BELOW NORMAL.
RIDGES COULD SEE MID TO UPPER 40S...WHILE THE VALLEYS COULD DIP BACK
INTO THE LOW 40S ONCE MORE.

SIMILAR STORY FOR TOMORROW...AS HIGH PRESSURE REMAINS OVERHEAD. VERY
LITTLE MOISTURE ACROSS THE AREA WILL CUT DOWN ON DEW POINTS AS WELL
AS CLOUD POTENTIAL. TEMPERATURES WILL CONTINUE TO MODIFY UPWARDS
WITH ABUNDANT SUNSHINE AND A SLIGHT WIND SHIFT TO THE EAST. HIGHS
WEDNESDAY AFTERNOON WILL BE MUCH CLOSER TO SEASONABLE
NORMS...REACHING THE MID AND UPPER 70S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 405 AM EDT TUE SEP 23 2014

THE PERIOD IS EXPECTED TO BEGIN WITH A DEEP UPPER TROUGH NEARING THE
PACIFIC COAST...AN UPPER LEVEL RIDGE CENTERED OVER THE FOUR CORNERS
REGION WITH ANOTHER CENTERED OVER THE SOUTHERN PLAINS/LOWER MS VALLEY AND
EXTENDING NORTHEAST INTO THE MID MS VALLEY REGION AND ANOTHER UPPER
LEVEL RIDGE CENTERED IN THE VICINITY OF BERMUDA. THE MAIN JET WILL BE
DISPLACED WELL NORTH OF THE US/CANADIAN BORDER FROM THE CENTRAL TO
EASTERN CONUS. HOWEVER...THERE WILL ALSO BE WEAKNESSES/WEAK UPPER
LEVEL TROUGHS IN BETWEEN THESE UPPER LEVEL RIDGE CENTERS. THE REGION
SHOULD BEGIN THE PERIOD WITH ONE OF THESE CENTERED TO OUR EAST AND
SOUTHEAST.

THIS UPPER LEVEL TROUGH INITIALLY CENTERED TO OUR EAST AND SOUTHEAST
SHOULD MOVE INTO THE NORTHEAST AND MID ATLANTIC STATES BY THU NIGHT
AND FRIDAY PER THE 0Z GUIDANCE WITH ANOTHER WEAKNESS INITIALLY TO OUR
NORTHWEST MOVING TO THE MID MS VALLEY/PLAINS STATES AT THAT POINT
WITH RIDGING BUILDING ACROSS THE SOUTHEASTERN CONUS AND FROM THE
NORTHERN PLAINS INTO THE GREAT LAKES REGION. THIS WILL PUT THE REGION
UNDER THE INFLUENCE OF UPPER RIDGING TO BEGIN THE WEEKEND. MODEL
AGREEMENT THEN DECREASES LATER IN THE PERIOD WITH THE UPPER LEVEL LOW
THAT IS EXPECTED TO MOVE SOUTHWEST ACROSS THE PLAINS STATES FROM
FRIDAY INTO SATURDAY AND MERGES WITH ANOTHER WEAKNESS OVER THE
SOUTHERN PLAINS/RIO GRANDE VALLEY...AND WHEN OR IF IT GETS KICKED
NORTH AND EAST BY THE TROUGH WORKING INTO AND ACROSS PARTS OF THE
WESTERN US FROM THE END OF THE WEEK AND EARLY NEXT WEEK. THE 0Z
ECMWF IS ABOUT 12 HOURS QUICKER THAN THE 0Z GFS IN SHEARING THIS
SYSTEM ON INTO THE NORTHERN ROCKIES REGION AND IS SLOWER TO BRING THE
PLAINS UPPER LEVEL SYSTEM AND DEEPER MOISTURE INTO THE OH VALLEY AND
MS VALLEY REGION AND IS SLOWER WORKING THIS UPPER SYSTEM ACROSS THE
AREA AS COMPARED TO THE 12Z RUN FROM THE 22ND. THERE HAVE ALSO BEEN
SOME RECENT GFS RUNS THAT ARE SLOWER TO BRING THE PLAINS UPPER LEVEL
SYSTEM INTO THE AREA AND THE DEEPER MOISTURE COMPARED TO THE 0Z RUN.

OVERALL...THE PATTERN SHOULD BE RATHER BENIGN INTO AT LEAST THE FIRST
PART OF THE WEEKEND...WITH TEMPERATURES AND DEWPOINTS GRADUALLY
MODERATING. WITH SFC HIGH PRESSURE INITIALLY CENTERED TO OUR NORTH AND
NORTHEAST AND THEN SFC PRESSURES RISE OVER THE GREAT LAKES WITH THE
RIDGE BUILDING TO OUR NORTH THU INTO FRI AND THE SFC RIDGE REMAINING
IN PLACE THERE INTO THE WEEKEND...SOME MODERATE RIDGE/VALLEY
TEMPERATURE SPLITS WILL REMAIN POSSIBLE ALONG WITH PATCHY RIVER
VALLEY FOG FROM AT LEAST WED NIGHT INTO FRI NIGHT AND POSSIBLY
SATURDAY NIGHT AS WELL. CLOUDS WILL INCREASE LATE IN THE PERIOD AS
WELL AS CHANCES FOR PRECIPITATION. ATTM...WE OPTED TO GO MORE WITH
PERSISTENCE AND HELD OF ON ANY POPS UNTIL SUNDAY AND MONDAY...THOUGH
THE MODEL CONSENSUS BLEND WOULD BRING SOME SLIGHT POPS INTO THE WEST
AND SOUTHWEST ON SUNDAY. CONFIDENCE IN THE TIMING OF THIS SYSTEM LATE
IN THE PERIOD REMAINS BELOW AVERAGE.INSTABILITY MIGHT BECOME GREAT
ENOUGH FOR AN ISOLATED THUNDERSTORM ON MONDAY...DEPENDING ON TIMING
OF THE MOISTURE INCREASE AND UPPER LEVEL SYSTEM.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 154 PM EDT TUE SEP 23 2014

THE ENTIRE AREA IS VFR ONCE AGAIN AS THE FOG WAS HARDER TO BURN OFF
IN THE FAR EASTERN PORTION OF EASTERN KENTUCKY. THE AIR IS FAIRLY DRY
OVER THE AREA AND WILL ALLOW FOR SOME RADIATIVE COOLING TONIGHT.
LOOKING MAINLY AT THE CROSSOVER TEMPERATURES...THE MOST LIKELY
STATION TO GO TO IFR OR BELOW IS SJS. THE LOW FORECAST FOR LOZ WILL
BE NEAR THE CROSSOVER TEMPERATURE...SO PUT SOME MVFR MIST IN THE
FORECAST FOR THERE. THE REST OF THE TAF STATIONS SHOULD STAY VFR. THE
VALLEYS WILL SEE PATCHY DENSE FOG TONIGHT AND WILL SEE VLIFR
CONDITIONS. ALL THE FOG SHOULD BURN OFF BETWEEN 12 AND 14Z AND BE
BACK TO VFR FOR THE REST OF THE DAY AND EARLY EVENING.

&&

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

$$

UPDATE...JJ
SHORT TERM...JMW
LONG TERM...JP
AVIATION...JJ





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