Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 222315 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
715 PM EDT WED APR 22 2015

.UPDATE...
ISSUED AT 715 PM EDT WED APR 22 2015

23Z SFC ANALYSIS SHOWS A COLD FRONT SOUTHEAST OF THE STATE THAT
HAS TAKEN THE CLOUDS AND ANY PCPN SOUTH ALONG WITH IT. IN ITS
WAKE...BREEZY WEST TO NORTHWEST WINDS OF 10 TO 20 MPH...WITH
HIGHER GUSTS...ARE BRINGING IN DRIER AND COOLER AIR. TEMPERATURES
VARY FROM THE MID 50S IN THE NORTH TO THE MID 60S SOUTH. WHILE
DEWPOINTS ARE FALLING OFF FASTER IN THE NORTH NOW DOWN TO THE LOW
AND MID 20S WHILE MID 40S ARE HOLDING ON IN THE FAR SOUTHEAST. THE
WINDS WILL DIE DOWN LATER THIS EVENING AND HELP SET THE STAGE FOR
A CHILLY NIGHT. IN FACT...A FEW SHELTERED VALLEY LOCATIONS IN THE
NORTH COULD SEE READINGS NEAR FREEZING BY DAWN. THIS COLD AIR WILL
BE ACCOMPANIED BY THE FORMATION OF FROST FOR A GOOD PORTION OF THE
NORTHWEST HALF OF THE JKL CWA. ACCORDINGLY...HAVE HOISTED A FROST
ADVISORY FOR OUR NORTHWEST MOST COUNTIES. IN THE ADVISORY AREA
VALLEY LOCATIONS WILL BE PARTICULARLY PRONE TO FROST. PATCHY
FROST CAN BE ANTICIPATED IN THE DEEPER VALLEYS OUTSIDE OF THE
ADVISORY AREA. FOR THESE LOCATIONS AN SPS IS IN EFFECT MENTIONING
THE FROST THREAT. THE GRIDS HAVE BEEN UPDATED TO REFLECT THE
ENHANCED FROST THREAT ALONG WITH ADJUSTMENTS TO TEMPS AND
DEWPOINTS BASED ON THE LATEST SHORTBLEND GUIDANCE...OBS...AND
TRENDS. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS
ALONG WITH FRESH ISSUANCES OF ZONES AND THE HWO.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 315 PM EDT WED APR 22 2015

CURRENT CONDITIONS ACROSS THE AREA FEATURE A POTENT COLD FRONT
MOVING THROUGH EAST KENTUCKY THIS EVENING. QUITE A TIGHT GRADIENT
ASSOCIATED WITH THIS HAS RESULTED IN SOME STRONG WESTERLY WINDS
AND SOME GUSTS TO 30 KNOTS IN SOME LOCATIONS. MAY NEED TO MENTION
THESE WINDS IN THE HWO AND CONTINUED INTO THE EVENING. TO THE
NORTH...SOME LOW LEVEL STRATO CU WILL BE MOVING THROUGH. THIS
SHOULD STAY TO THE NORTH AND NOT MAKE IT INTO EAST KENTUCKY
TONIGHT. UPSTREAM...THE TIGHTER GRADIENT IN PLACE AND LOOSENING A
BIT THROUGH TONIGHT SHOULD KEEP WINDS UP TONIGHT ENOUGH THAT FROST
DEVELOPMENT TO SHELTERED VALLEYS TONIGHT. THEREFORE...WILL MENTION
THIS IN AN SPS. IN FACT...SHELTERED VALLEY TEMPS MAY MAKE IT INTO
THE LOWER 30S TONIGHT...ESPECIALLY WITH THE AIR MASS DESCENDING ON
EAST KENTUCKY TONIGHT.

HOWEVER...HEADING INTO THURSDAY AND THURSDAY NIGHT...HIGH
PRESSURE WILL MOVE INTO THE AREA WITH STRONG SUBSIDENCE. WILL
EXPECT CLEAR SKIES THURSDAY AND THURSDAY NIGHT. WINDS WILL SLOWLY
BE SLACKENING OFF THROUGH THE DAY AND BECOMING NEAR CALM FOR
TOMORROW NIGHT. THIS COUPLED WITH LOW TEMPS ON THURSDAY NIGHT
DROPPING INTO THE LOWER 30S AND EVEN THE UPPER 20S IN THE DEEPER
VALLEYS DUE TO THE AIR MASS DESCENDING ON THE EAST KENTUCKY WILL
LEAD TO A MORE WIDESPREAD FROST DEVELOPMENT AND EVEN CONDITIONS
POSSIBLE FREEZE CONDITIONS. FOR THIS...WILL ALSO INCLUDE THIS
PERIOD MENTIONED IN THE SPS AS WELL AS THE HWO.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 315 PM EDT WED APR 22 2015

THE EXTENDED PERIOD WILL START OUT DRY AS SOME MINOR RIDGING AND SFC
HIGH PRESSURE SITS OVER THE REGION. THIS IS FAIRLY SHORT LIVED AS
THE HIGH DEPARTS OVERNIGHT FRIDAY NIGHT. CLOUDS AND LL MOISTURE WILL
THEN BE ON THE INCREASE AHEAD OF A LOW PRESSURE SYSTEM THAT IS
PROGGED TO MOVE INTO THE OH VALLEY EARLY SATURDAY MORNING. MODELS
SHOW SOME SUPPRESSION/DAMPENING OF THIS LOW AS IT MOVES ACROSS THE
EASTERN CONUS DUE TO THE LOW PRESSURE BLOCK SET UP OFF THE NEW
ENGLAND COAST. THIS WILL HAVE AN IMPACT ON HOW MUCH PRECIP WE CAN
GET OUT OF THE SYSTEM AS IT PASSES THROUGH. ADDITIONALLY...SOUTHEAST
FLOW/DOWNSLOPING AT THE ONSET OF THE EVENT MAY HELP DECREASE PRECIP
AMOUNTS AS WELL. THE LOW WILL DEPART THE REGION BY SUNDAY MORNING.
ON ITS HEELS...A PIECE OF UL ENERGY WILL QUICKLY SWING THROUGH
KENTUCKY KEEPING RAIN CHANCES IN THE FORECAST THROUGH SUNDAY
EVENING.

THINGS WILL DRY OUT ON MONDAY BEFORE A CUT OFF LOW MOVES TOWARD THE
REGION. HOWEVER...THIS IS WHERE MODELS DIFFER SUBSTANTIALLY WITH THE
PLACEMENT OF THE CUTOFF LOW. THE GFS TRACKS THE CUTOFF LOW FURTHER
NORTH...WHICH WOULD PUT EASTERN KENTUCKY IN A PROLONGED WET AND
UNSETTLED PATTERN. ON THE OTHER HAND THE ECMWF TRACKS THE LOW
FURTHER SOUTH ALONG THE GULF COAST...WHICH WOULD PROVIDE US WITH AN
EXTENDED DRY PERIOD. THAT BEING SAID...FORECAST CONFIDENCE IS LOW
BEYOND THE MONDAY TIME FRAME SO HAVE STUCK CLOSE TO THE CR
SUPERBLEND.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 715 PM EDT WED APR 22 2015

IN THE WAKE OF A COLD FRONT CROSSING THE AREA HIGH PRESSURE IS
BUILDING INTO THE REGION. AS A RESULT...EXPECT VFR CIGS AND VIS
ACROSS ALL TAF SITES THROUGH THE ENTIRE PERIOD. NORTHWEST TO WEST
WINDS WILL STAY UP IN THE 10 TO 20 KT RANGE UNTIL LATER IN THE
EVENING WHEN THEN WILL SETTLE TO BETWEEN 5 AND 10 KTS. LOOK FOR
THE WEST TO NORTHWEST WINDS TO BECOME GUSTY AGAIN THURSDAY
AFTERNOON.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 3 AM TO 8 AM EDT THURSDAY FOR KYZ044-050>052-
058>060-104-106-108-111.

&&

$$

UPDATE...GREIF
SHORT TERM...SHALLENBERGER
LONG TERM...JVM
AVIATION...GREIF



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