Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 062328 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
728 PM EDT FRI MAY 6 2016

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 358 PM EDT FRI MAY 6 2016

THE RECENT OMEGA BLOCKY PATTERN WILL BEGIN TO BREAK DOWN TO START
THE WEEKEND AS THE UPPER LOW NOW OVER THE MID ATLANTIC STATES
WILL DRIFT NORTH AND THEN OFF THE EASTERN SEABOARD. THIS UPPER LOW
WILL EVENTUALLY BEGIN TO MERGE WITH AN UPPER LEVEL LOW MOVING
SOUTHEAST FROM THE HUDSON BAY REGION INTO THE JAMES BAY AREA
THROUGHOUT THE PERIOD. A SHORTWAVE TROUGH AROUND THE UPPER LOW AND
INTO THE GREAT LAKES REGION LATE TONIGHT AND ON SATURDAY AND THEN
ACROSS THE UPPER OH VALLEY REGION AND INTO THE NORTHEAST SATURDAY
NIGHT. IN ADVANCE OF THIS SHORTWAVE TROUGH...A SFC LOW WILL TRACK
ACROSS ONTARIO AND INTO EASTERN QUEBEC AND THE ST LAWRENCE VALLEY
BY THE END OF THE PERIOD. A TRAILING COLD FRONT WILL PUSH SOUTH
INTO THE OHIO VALLEY REGION LATE SATURDAY SAGGING AS FAR SOUTH AS
THE JKL CWA BY THE END OF THE PERIOD AS IT BEGINS TO STALL IN
RESPONSE TO RISING HEIGHTS ACROSS THE SOUTHEAST.

CU SHOULD DISSIPATE AROUND OR SHORTLY AFTER SUNSET AND ALLOW FOR
VALLEY LOCATIONS TO DECOUPLE RATHER QUICKLY. THIS SHOULD SET THE
STAGE FOR VALLEY LOCATIONS COOLING WELL INTO THE 40S AND VALLEY
FOG TO FORM. THIS FOG COULD BECOME DENSE PENDING TIMING OF
ANTICIPATED INCREASE IN CLOUDS LATE. THE CLOUDS ARE EXPECTED AS AN
AREA OF ISENTROPIC LIFT ASSOCIATED WITH A WEAK MID LEVEL WAVE
BEGINS TO WORK IN DURING THE SECOND HALF OF TONIGHT AND INTO THE
DAY ON SATURDAY. CLOUDS SHOULD INCREASE LATE TONIGHT AND A FEW
SPRINKLES OR ISOLATED SHOWERS CANNOT BE RULED OUT TOWARD DAWN IN
THE WESTERN PART OF THE AREA...AND DURING THE MORNING HOURS ACROSS
THE REMAINDER OF THE AREA. DAYTIME HEATING AND INCREASING MOISTURE
AHEAD OF THE APPROACHING COLD FRONT COULD LEAD TO MLCAPE OF 1000
J/KG OR MORE ACROSS THE NORTH AND EASTERN PART OF THE AREA BY
EARLY EVENING WITH OTHER INSTABILITY INDICES GENERALLY MARGINALLY
UNSTABLE. MID LEVEL FLOW WILL ALSO INCREASE AHEAD OF THE
FRONT...AND MIXING COULD LEAD TO GUSTS AS HIGH AS THE 25 TO 30 MPH
RANGE ON SATURDAY AFTERNOON. CONFIDENCE IN THE EVOLUTION AND
TIMING OF CONVECTION IS NOT EXTREMELY HIGH...BUT THE BEST CHANCE
OF CONVECTION IN MOST LOCATIONS SHOULD BE AROUND SUNSET...IF NOT
AFTER WHEN UPPER LEVEL FORCING IS BEST. A FEW OF THE STORMS COULD
BECOME STRONG TO PERHAPS LOCALLY SEVERE MAINLY IN NORTHERN
LOCATIONS ALONG AND NORTH OF THE MTN PARKWAY.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 336 PM EDT FRI MAY 6 2016

A COLD FRONT IS EXPECTED TO BE SLOWLY SINKING SOUTHWARD THROUGH THE
AREA AS THE PERIOD STARTS...AND SHOWERS MAY BE ONGOING IN SOME
LOCATIONS. THE FRONT IS EXPECTED TO STALL NEAR OUR SOUTHERN
BORDER...AND THEN REVERSE AND HEAD BACK NORTH AS A WARM FRONT IN
RESPONSE TO A LARGE AREA OF LOW PRESSURE OVER THE CENTRAL PLAINS.
THE WARM FRONT SHOULD PASS THROUGH THE JKL FORECAST AREA ON SUNDAY
NIGHT AND MONDAY MORNING. THE PROXIMITY OF THE FRONT WILL KEEP THE
THREAT OF PRECIP ALIVE...BUT THE BETTER UPPER LEVEL SUPPORT AND
BETTER FLOW OFF THE GULF OF MEXICO WILL BE MUCH FURTHER TO OUR WEST
ON SUNDAY AND MONDAY. THE ENTIRE REGIME WILL SHIFT EASTWARD...AND WE
WILL SEE A HIGHER POP IN OUR AREA ON TUESDAY/TUESDAY NIGHT AS A
WEAKENED PIECE OF THE CENTRAL PLAINS SYSTEM MOVES BY TO OUR NORTH.
THERE ARE SOME MODEL DIFFERENCES WHICH BECOME MORE APPARENT AT THIS
POINT...WITH THE 00Z ECMWF SHOWING SOME DEGREE OF PHASING WITH AN
UPPER TROUGH DROPPING THROUGH NEW ENGLAND...AND THE GFS MUCH MORE
RESERVED. THERE ARE ALSO DIFFERENCES HANDLING AN UPPER LEVEL SYSTEM
MOVING ACROSS THE NORTH CENTRAL CONUS. AT THE SURFACE...THE RESULT
HAS THE 00Z ECMWF DROPPING THE FRONT BACK SOUTH THROUGH THE AREA ON
WEDNESDAY DUE TO A GREATER INFLUENCE FROM THE FIRST SYSTEM PHASING
WITH THE NORTHEAST CONUS TROUGH. MEANWHILE... THE GFS DOES NOT HAVE
ANOTHER COLD FRONTAL PASSAGE UNTIL THURSDAY...AND THIS IS A WEAK
FRONT IN ASSOCIATION WITH THE WAVE MOVING ACROSS THE NORTHERN CONUS.
THE 00Z ECMWF ALSO HAS A COLD FROPA DUE TO THE NORTHERN SYSTEM...BUT
IT IS SLOWER AND DOES NOT OCCUR UNTIL THURSDAY NIGHT AND FRIDAY.
WITH SUCH INCONSISTENCY...THERE IS NOT GOOD CONFIDENCE IN THE
OUTCOME AFTER TUESDAY...AND A BROAD BRUSHED BLEND IS USED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 728 PM EDT FRI MAY 6 2016

A MIX OF LOW...MIDDLE...AND HIGH LEVEL CLOUDS ARE EXPECTED TO
STREAM ACROSS THE SKIES OF EASTERN KENTUCKY DURING THE TAF PERIOD.
THE CLOUDS WILL VARY IN COVERAGE FROM FEW TO BKN. SCT TO BKN MID
AND HIGH LEVEL CLOUDS WILL DOMINATE THROUGH 11 OR 12Z SATURDAY.
DURING THE DAY ON SATURDAY...THE LOW LEVEL CLOUDS WILL GRADUALLY
INCREASE IN COVERAGE AS A FRONT SAGS SOUTHWARD TOWARD OUR AREA
FROM THE OHIO VALLEY. BY 18Z OR SO THE CLOUDS SHOULD BE BKN WITH
BASES BETWEEN 5 AND 7K...ESPECIALLY NORTH OF THE HAL ROGERS
PARKWAY AND HIGHWAY 80 CORRIDOR. A FEW RAIN SHOWERS AND
THUNDERSTORMS ARE FORECAST TO WORK THERE WAY INTO OUR FAR NORTHERN
COUNTIES...WITH SYM AND SJS PERHAPS BEING AFFECTED TOWARD THE END
OF THE TAF PERIOD. WINDS COULD BECOME STRONG AND GUSTY BY 15Z OR
SO...WITH SUSTAINED VALUES OF AROUND 10KTS FROM THE WEST...WITH
GUSTS OF AROUND 20KTS POSSIBLE AT TIMES. THE WINDS SHOULD DIE
DOWN A BIT AND BECOME LESS GUSTY ONCE THE CLOUDS BEGIN TO LOWER
AND THICKEN AND LESS SUN REACHES THE SURFACE.

&&

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

$$

SHORT TERM...JP
LONG TERM...HAL
AVIATION...AR


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