Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 230020
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
820 PM EDT TUE APR 22 2014

.UPDATE...
ISSUED AT 820 PM EDT TUE APR 22 2014

UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. THE SHOWERS HAVE ALL MOVED OFF TO THE EAST AND WILL BE
EXPECTING A QUIET NIGHT. THE WINDS HAVE BEEN A LITTLE SLOW TO DIE
DOWN TONIGHT AND SO THE TEMPERATURES HAVE ALSO BEEN SLOW TO DROP
BECAUSE OF THE MIXING. EXPECTING THE WINDS TO DIE DOWN AND THE TEMPS
TO START DROPPING FASTER OVER THE NEXT TWO HOURS. THE REST OF THE
FORECAST IS ON TRACK.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 333 PM EDT TUE APR 22 2014

CURRENT CONDITIONS AS OF 19Z FEATURE SOME ISOLATED SHOWERS HANGING
AROUND THE AREA AS THE FRONT STILL LIES JUST TO THE WEST AS IT BEGINS
TO CROSS THE I-75 CORRIDOR. THIS WILL ESSENTIALLY BRING AN END TO
THE SHOWER ACTIVITY THIS EVENING. OBS UPSTREAM HAVE DEWS IN THE LOWER
TO MID 30S MOVING INTO THE AREA ALONG WITH MUCH COOLER TEMPS. THIS
AIR MASS WILL BE MOVING IN OVER EASTERN KENTUCKY FOR TONIGHT AND WITH
CLEARING SKIES BEHIND THE FRONT...TEMPS WILL FALL INTO THE 30S
TONIGHT...ESPECIALLY IN THE BLUEGRASS AND IN THE SHELTERED VALLEYS.
THEREFORE...WILL GO WITH AN SPS MENTIONING THE FROST POTENTIAL
TONIGHT. THIS WILL MOSTLY BE THE VALLEYS AS SOME OF THE RIDGE TONIGHT
WILL KEEP SOME STRONGER WINDS...AND WILL SHOW A BIT OF A RIDGE
VALLEY SPLIT TONIGHT BUT ONLY AROUND A 5 DEGREE DIFFERENCE.

HEADING INTO TOMORROW...THE SHOWER ACTIVITY TODAY DID NOT PROVIDE
MUCH OF A SOAKING...ESPECIALLY GIVEN THE SCATTERED NATURE TODAY AND
SO THE RELATIVE HUMIDITY VALUES TONIGHT WILL NOT RECOVER MUCH ABOVE
70 PERCENT IN MOST PLACES. AS WELL...MODEL SOUNDINGS SHOW QUITE A DRY
POCKET OF AIR ALOFT TOMORROW TO MIX DOWN AND WHILE WE WILL LIKELY NOT
MIX INTO THE STRONGER WINDS ABOVE...RH WILL STILL BE DOWN INTO THE
CRITICAL VALUES TOMORROW AFTERNOON AND SO WILL MENTION FIRE WEATHER
IN THE SPS AS WELL. WITH HIGH PRESSURE REMAINING IN CONTROL THROUGH
TOMORROW NIGHT...WILL KEEP A DRY FORECAST THROUGH THE SHORT TERM AND
KEEP SKY COVER MOSTLY CLEAR. THE COOLER AIR MASS WILL REMAIN OVER THE
AREA THROUGH TOMORROW NIGHT AS LOW TEMPS WILL GET DOWN INTO THE LOW
40S ON THE RIDGES AND INTO THE LOW 30S IN SOME OF THE DEEPER VALLEYS.
THE RIDGE SHIFTING THROUGH THE AREA WILL KEEP CLOUD COVER MOSTLY
CLEAR AND ANOTHER NIGHT OF RADIATIONAL COOLING WILL ENSUE AS A RIDGE
VALLEY SPLIT OF 10 DEGREES WILL BE IN PLACE. FROST ALSO LOOKS TO BE
ANOTHER THREAT THURSDAY MORNING.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 437 PM EDT TUE APR 22 2014

SURFACE HIGH PRESSURE WILL BE JUST TO OUR EAST AND A MID/UPPER LEVEL
RIDGE PASSING OVER AT THE START OF THE PERIOD...BRINGING FAIR WEATHER
ON THURSDAY. A LARGE BUT FAST MOVING LOW AMPLITUDE TROUGH OVER THE
GREAT PLAINS WILL BE MOVING EAST ALONG WITH AN ASSOCIATED SURFACE LOW
AND COLD FRONT...WITH THE FRONT PASSING THROUGH THE LOCAL AREA LATE
THURSDAY NIGHT OR FRIDAY. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS
ARE LIKELY AHEAD OF THE FRONT. MODELS ARE ALREADY SHOWING SOME
DISCREPANCY AT THIS POINT...AND A BLEND WAS USED...WITH THE HIGHEST
POPS THURSDAY NIGHT...BUT WITH PRECIP POSSIBLY LINGERING INTO FRIDAY.

DISAGREEMENT IN THE MODELS CONTINUES THROUGH THE REMAINDER OF THE
LONG TERM PERIOD. ONE THING AT ODDS IS WHETHER OR NOT THERE WILL BE A
REINFORCING SHOT OF COLDER AIR WHICH MAKES IT IN DURING THE
WEEKEND...AND THE SUBSEQUENT POSITION OF THE FRONT WHEN IT STALLS.
THIS LEADS TO LOW CONFIDENCE FOR TEMPERATURES...AND TO SOME EXTENT
FOR THE POP AS WELL...SINCE THE GREATEST POP SHOULD BE NEAR AND NORTH
OF THE FRONTAL BOUNDARY.

A POTENT SYSTEM MOVING ONSHORE ON THE WEST COAST ON FRIDAY WILL ROLL
EAST...WITH THE MID/UPPER LEVEL TROUGH EXPECTED TO FORM A CLOSED
UPPER LOW OVER THE MIDDLE OF THE CONUS. SURFACE LOW PRESSURE WILL
ALSO DEVELOP IN RESPONSE TO THIS. THE ENTIRE SYSTEM THEN SLOWLY MOVES
EAST. MODELS DO AGREE ON THIS OVERALL SCENARIO...BUT SHOW SO MUCH RANGE
IN THE DETAILS THAT ONLY A GENERALIZED FORECAST CAN BE GIVEN AT THIS
POINT. HAVE USED AN INCREASE IN POPS AS TIME GOES BY EARLY NEXT WEEK
DUE TO THE APPROACH OF THE LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 820 PM EDT TUE APR 22 2014

SKIES HAVE CLEARING OUT AS THE FRONT MOVES TO THE SOUTH AND EAST OF THE
AREA. EXPECT VFR FOR THE NEXT 24 TO 36 HOURS.

&&

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

$$

UPDATE...JJ
SHORT TERM...SHALLENBERGER
LONG TERM...HAL
AVIATION...JJ






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