Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 220034
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
734 PM EST FRI NOV 21 2014

.UPDATE...
ISSUED AT 733 PM EST FRI NOV 21 2014

JUST ISSUED A NEW SET OF ZONES FEATURING CHANGES MADE TO THE
TEMPERATURE FORECAST FOR NEXT THURSDAY...THURSDAY NIGHT AND FRIDAY
TIME PERIOD. THE TEMPERATURES WE HAD IN THE FORECAST BEFORE FOR THIS
PART OF THE FORECAST PERIOD WERE AT LEAST 6 TO 7 DEGREES WARMER THAN
SOME OF OUR NEIGHBORS. THE DEW POINTS AND WEATHER GRIDS WERE ALSO
RERAN BASED ON THE NEW TEMPERATURES.

UPDATE ISSUED AT 635 PM EST FRI NOV 21 2014

THE FORECAST HAS BEEN ON TRACK SO FAR THIS EVENING...SO NO UPDATE IS
PLANNED AT THIS TIME. HOWEVER...SOME OF OUR FORECAST GRIDS FOR NEXT
THURSDAY AND THURSDAY NIGHT ARE QUITE A BIT OUT OF SYNC WITH SOME OF
OUR NEIGHBORS...SO SOME ADJUSTMENTS WILL BE MADE TO CORRECT THIS
ISSUE LATER IN THE SHIFT...ALONG WITH ANY OTHER NECESSARY UPDATES.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 335 PM EST FRI NOV 21 2014

SURFACE HIGH PRESSURE PASSING OVER THE REGION TODAY WILL MOVE TO OUR
EAST TONIGHT...WITH WARM AIR ADVECTION BEGINNING AS LOW LEVEL FLOW
TURNS TO THE SOUTH. ISENTROPIC LIFT IN THE WARM AIR ADVECTION WILL
ALSO BRING SOME CLOUDS TO THE REGION LATE TONIGHT AND SATURDAY...
ESPECIALLY IN OUR FAR NW COUNTIES. HOWEVER...MODEL TRENDS SUGGEST
THAT ANY PRECIP SHOULD REMAIN NW OF THE JKL FORECAST AREA. AN
UPPER LOW/SHORTWAVE TROUGH OVER THE FAR SW CORNER OF THE CONUS TODAY
WILL MOVE TO TX SATURDAY NIGHT...BEFORE THEN TURNING NE AND PHASING
WITH A NORTHERN STREAM SYSTEM CATCHING UP WITH IT. THIS SYSTEM WILL
JUST BE STARTING TO TAKE SHAPE AT THE END OF THE PERIOD...AND WILL
RESULT IN INCREASING CLOUDS AND AN INCREASE IN LOW LEVEL FLOW FOR OUR
LOCAL AREA. IT STILL APPEARS THAT PRECIP WITH THIS SYSTEM WILL HOLD
OFF UNTIL AFTER SATURDAY NIGHT.

THAT BEING SAID...TEMPERATURES COULD BE THE TRICKIEST PART OF THE
SHORT TERM PERIOD. OUR FIRST NIGHT WILL START OUT WITH A TYPICAL
DIURNAL DOWNTURN IN TEMPS...WITH VALLEYS LEADING THE WAY.
HOWEVER...AS LOW LEVEL FLOW INCREASES DURING THE NIGHT...RIDGES AS
WELL AS OPEN TERRAIN IN THE WESTERN PART OF THE FORECAST AREA SHOULD
SEE TEMPS LEVEL OFF OR EVEN RISE OVERNIGHT. CLOUDS IN THE FAR NW
TOWARD DAWN WILL ALSO AID IN THIS TREND. MEANWHILE...VALLEYS IN THE
EAST WILL LIKELY MAINTAIN THEIR COLD READINGS OVERNIGHT...OR EVEN
CONTINUE TO FALL VERY SLOWLY. EXACTLY WHERE THE TRANSITION FROM ONE
TEMPERATURE REGIME TO THE OTHER OCCURS WILL BE VERY DIFFICULT TO
DELINEATE. SKIES BECOMING PARTLY TO MOSTLY SUNNY ON SATURDAY...ALONG
WITH TEMPS ALOFT CONTINUING TO WARM...WILL ALLOW FOR A SUBSTANTIAL
WARM-UP TO NEAR NORMAL READINGS. THE TEMPERATURE FORECAST FOR
SATURDAY NIGHT WILL POSE ESSENTIALLY THE SAME CHALLENGES AS TONIGHT...
EXCEPT LOW LEVEL FLOW WILL BECOME STRONGER...AND CLOUDS WILL BE ON
THE INCREASE NOT ONLY IN THE NW BUT ALSO IN THE SW PART OF THE AREA.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 335 PM EST FRI NOV 21 2014

UPPER LEVEL SHORTWAVE IS EXPECTED TO BE CENTERED NEAR AND AROUND THE
ARKLATEX REGION BY SUNDAY MORNING. THIS UPPER LEVEL FEATURE WILL
TRACK NE AS IT BEGINS TO PHASE WITH THE LONG WAVE TROUGH LOCATED IN
THE WESTERN US EARLY NEXT WEEK. THIS WILL CONTINUE TO DEEPEN A
ASSOCIATED SURFACE LOW THAT WILL TRACK NE INTO THE MIDDLE MISSISSIPPI
RIVER VALLEY. ATTENDANT WARM FRONT WILL CONTINUE TO SURGE NORTH
THROUGH THE DAY SUNDAY. THE 06Z GFS CONTINUES TO MOVE PRECIP IN
SLOWER WHILE THE 00Z ECMWF/06 NAM ARE A BIT FASTER. PREVIOUS FORECAST
HAD A GRADIENT AND LEANED THAT DIRECTION GIVEN THAT IT IS A DECENT
COMPROMISE TO SOME OF THE TIMING DIFFERENCES THAT HAVE BEEN SEEN.
THERE COULD BE A DOWNSLOPE COMPONENT TO THIS SYSTEM AS MENTIONED IN
PREVIOUS DISCUSSION...HOWEVER I THINK THIS WOULD BE TRANSLATED MORE
IN THE QPF. THEREFORE PLAN TO PUT HIGHER POPS IN THE FORECAST FOR
SUNDAY AFTERNOON SINCE RAIN DOES LOOK AT LEAST LIKELY. RAIN WILL DIE
OFF SUNDAY NIGHT AS WARM FRONT CONTINUES TO MOVE NORTH OF THE REGION.
THIS WARM FRONT DOES FINALLY BRING SOME SLIGHTLY ABOVE NORMAL HIGH
TEMPS ACROSS THE CWA SUNDAY.

MOVING INTO MONDAY EXPECT A COLD FRONT TO CROSS THE REGION THROUGH
THE DAY. GIVEN DRIER AIR FILTERING IN ALOFT LIGHTER QPF AND POP
AMOUNTS WILL BE MORE SLIGHT TO CHANCE SIDE. GIVEN DECENT MIXING AND
STRONG UPPER LEVEL JET ACROSS THE REGION WILL LEAD TO A BREEZY DAY
ACROSS THE REGION. SURFACE HIGH BEGINS TO NUDGE EAST AS WE MOVE INTO
TUESDAY WITH GENERALLY DEEP TROUGH MOVING ACROSS MUCH OF THE EASTERN
US. MODELS DO COME INTO BETTER AGREEMENT ON DISTURBANCE LATER
WEDNESDAY INTO THURSDAY. AT THIS TIME WILL STICK CLOSE TO MODEL
CONSENSUS WHICH BRINGS SLIGHT POPS ACROSS THAT REGION. AFTER THIS
ECMWF DEVELOPS A SURFACE LOW ACROSS THE SOUTHERN MISSISSIPPI RIVER
VALLEY AND BRINGS IT NE INTO THE OHIO VALLEY BY LATE FRIDAY. WHILE
THE GFS HAS A REFLECTION OF THIS MUCH LATER IN THE MODEL RUN. AGAIN
GIVEN UNCERTAINTY WILL STICK CLOSE TO BLEND WHICH GIVES MORE IN THE
WAY OF SLIGHT TO CHANCE POPS INTO FRIDAY. OVERALL TEMPERATURES ARE
EXPECTED TO REMAIN BELOW NORMAL FROM TUESDAY THROUGH THE REST OF THE
LONG TERM.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 635 PM EST FRI NOV 21 2014

VFR CONDITIONS AND WINDS LESS THAN 10KTS ARE EXPECTED THROUGH THE
PERIOD. WE WILL SEE FLUCUATIONS IN CLOUD COVER FROM TIME TO TIME AS
A WEAK WARM FRONT PASSES BY ON SATURDAY...BUT NOTHING MORE THAN THAT
IS EXPECTED DURING THE TAF PERIOD AT THIS TIME.


&&

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

$$

UPDATE...AR
SHORT TERM...HAL
LONG TERM...DJ
AVIATION...AR





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