Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 291219 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
819 AM EDT FRI MAY 29 2015

.UPDATE...
ISSUED AT 819 AM EDT FRI MAY 29 2015

FRESHENED UP THE TEMPERATURES...DEW POINTS...AND SKY COVER OVER
THE NEXT FEW HOURS TO JIVE BETTER WITH CURRENT OBSERVATIONAL
TRENDS. ALSO SLOWED THE POPS A BIT MORE...ACCORDING TO THE LATEST
TRENDS IN THE HRRR MODEL.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 357 AM EDT FRI MAY 29 2015

NEARLY STATIONARY FRONTAL BOUNDARY IS CURRENTLY ALIGNED NORTH OF
THE OHIO RIVER. EASTERN KENTUCKY REMAINS ON THE MORE HUMID SIDE OF
THE BOUNDARY...WITH THE AIR MASS NOTICEABLY MORE STICKY COMPARED
TO THE LAST FEW DAYS. A WEAK IMPULSE OR TWO WILL ONCE AGAIN PASS
THROUGH THE MISSISSIPPI VALLEY IN BETWEEN THE UPPER RIDGE ALONG
THE EASTERN SEABOARD...AND THE TROUGH ESTABLISHED ACROSS THE
CENTRAL CONUS. EASTERN KENTUCKY WILL BE ON THE EDGE OF THE
TRAJECTORY OF THESE IMPULSES...HOWEVER GIVEN THE WEAKER CAP IN
PLACE AND LIKELY MORE INSTABILITY BUILDING TODAY COMPARED TO
YESTERDAY...SCATTERED CONVECTION SEEMS LIKE A GOOD BET. HIGHS
WILL BE WARMER COMPARED TO YESTERDAY...WITH LESS CLOUDS...GENERALLY
IN THE LOW TO MID 80S.

CONVECTION WILL DIE OFF WITH THE LOSS OF HEATING TONIGHT...WITH
LOWS GENERALLY IN THE LOW TO MID 60S...AND PATCHY
FOG SETTING UP...PARTICULARLY AT LOCATIONS THAT SEE SUSTAINED
RAINFALL. A COLD FRONT WILL BEGIN TO MAKE ITS PUSH ACROSS THE OHIO
VALLEY ON SATURDAY...HOWEVER THERE ALSO BE DRIER AIR IN THE LOW TO
MID-LEVELS. THIS WILL KEEP MORE OF A GRADIENT OF POPS ACROSS THE
AREA...WITH BETTER STORM CHANCES NEAR I-64...AND LESSER CHANCES TO
THE SOUTHEAST. HIGHS WILL RANGE FROM THE LOWER 80S IN THE
NORTH...TO THE UPPER 80S IN THE SOUTHEAST.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 412 AM EDT FRI MAY 29 2015

UPPER LEVEL RIDGING IS EXPECTED TO CONTINUE OFF THE SOUTHEAST CONUS
ACROSS THE WESTERN ATLANTIC THROUGH THE EXTENDED. MEANWHILE...
ANOTHER AREA OF UPPER LEVEL RIDGING MOVING INTO THE SOUTHWEST CONUS
WILL HELP TO BREAK DOWN THE OVERALL LONGWAVE TROUGHING PATTERN THAT
HAS EXISTED OVER MUCH OF THE LAST WEEK ACROSS THE REMAINDER OF THE
CONUS. BY SATURDAY NIGHT...KY WILL FIND ITSELF WEDGED IN BETWEEN
THESE TWO RIDGES...WITH UPPER LEVEL TROUGHING AMPLIFYING OVER THE
SOUTHERN MISSISSIPPI VALLEY AS IT BECOMES BLOCKED. EXPECT THIS
TROUGH TO FINALLY CLOSE OFF INTO A CLOSED LOW BY MONDAY
NIGHT...STAYING NEARLY STATIONARY THROUGH THE REMAINDER OF THE
EXTENDED...WHILE WEAK RIDGING SLIDES IN JUST NORTH OF THE OHIO RIVER
VALLEY. THIS PATTERN TO OUR SOUTH WILL KEEP UNSETTLED WEATHER
ACROSS MUCH OF KY THROUGH MUCH OF THE EXTENDED PERIOD.

AT THE SURFACE...EXPECT A LOW PRESSURE SYSTEM TO BE COLLOCATED WITH
THE UPPER LEVEL LOW...ACROSS THE SOUTHERN MISSISSIPPI VALLEY AT THE
START OF THE EXTENDED. A COLD FRONT WILL EXTEND FROM THIS LOW
NEWRD...ATTACHING TO ANOTHER LOW PRESSURE SYSTEM OFF THE EASTERN
COAST OF CANADA. AS SUCH...THIS BOUNDARY IS EXPECTED TO SPAN
ACROSS MUCH OF THE STATE OF KY THROUGH THE DAY SUNDAY...CREATING A
DRIVING FORCE FOR CONVECTIVE DEVELOPMENT...ESPECIALLY GIVEN THE
WARM MOIST AIRMASS IN PLACE ACROSS THE REGION. AND GIVEN THE
BLOCKED NATURE OF THIS CLOSED UPPER LEVEL LOW...EXPECT THERE TO BE
LITTLE MOVEMENT OF THE COLD FRONT...SHIFTING ONLY SLIGHTLY
SOUTHWARD TOWARDS THE TN BORDER THROUGHOUT THE REMAINDER OF THE
EXTENDED. THIS SLIGHT SHIFT WILL AT LEAST ALLOW SOME INFLUENCE OF
THE DEVELOP UPPER LEVEL RIDGING INTO THE NORTHERN HALF OF THE CWA.

EXPECT BEST CONVECTIVE DEVELOPMENT TO BE ON SUNDAY...AS HAS BEEN
HIGHLIGHTED IN PREVIOUS FORECASTS...GIVEN THE LOCATION OF THE
BOUNDARY OVER MUCH OF THE STATE. LITTLE IN THE WAY OF DIRECTIONAL
SHEER OR SPEED SHEER...AND SOUNDINGS WHICH SHOW HIGH AMOUNTS OF
MOISTURE THROUGHOUT THE COLUMN...WILL OFFSET ANY OF THE HIGHER CAPE
AMOUNTS DURING THE AFTERNOON. THUNDERSTORMS ARE LIKELY...BUT
ISOLATED HEAVY RAIN AND FREQUENT LIGHTNING WILL BE THE MAIN CONCERNS
WITH ANY STORMS THAT DEVELOP. THE BOUNDARY THEN SHIFTS
SOUTHWARD...WITH HIGH PRESSURE MOVING INTO THE NORTHERN HALF OF THE
CWA. THIS WILL CREATE A WIND SHIFT ACROSS MUCH OF THE CWA...WITH
COOLER AND MORE STABLE NW FLOW TAKING HOLD. TEMPERATURES WILL TAKE A
SLIGHT DOWNWARD TREND IN THIS REGIME...AS WILL THE AMOUNT OF
MOISTURE IN THE ATMOSPHERE. THAT BEING SAID...THE BOUNDARY WILL
STILL BE IN SUCH A CLOSE PROXIMITY THAT AFTERNOON CONVECTIVE
DEVELOPMENT...ESPECIALLY OVER THE SOUTH AND SE CWA...CANNOT BE RULED
OUT EACH DAY. SO ESSENTIALLY...POPS WILL REMAIN IN THE FORECAST
DURING THE DAYTIME HOURS THROUGH THE REMAINDER OF THE FORECAST
PERIOD. OVERALL COVERAGE ACROSS THE CWA WILL INCREASE THURSDAY AND
FRIDAY AS SOUTHERLY FLOW RETURNS AND MORE MOISTURE IS ADVECTED INTO
THE CWA.

GIVEN DECENT MODEL AGREEMENT DURING THE EXTENDED PERIOD...THE
SUPERBLEND OF MODELS SEEMED TO HANDLE POPS AND OTHER PARAMETERS
FAIRLY WELL. THE ONLY MAJOR ADJUSTMENT TO THE MODEL BLEND WAS TO
UNDERCUT POPS SOME DURING THE LATE NIGHT HOURS DUE TO LOSS OF
INSTABILITY IN THE ATMOSPHERE WHICH THE SUPERBLEND 12 HOUR GRIDS ARE
JUST NOT CAPABLE OF PICKING UP ON. TEMPS...WINDS...AND CLOUD COVER
ALL SEEMED QUITE REASONABLE AND WITHIN GOOD AGREEMENT OF SURROUNDING
OFFICES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 819 AM EDT FRI MAY 29 2015

IFR OR WORSE FOG WILL BE BURNING OFF THROUGH 13Z. SCATTERED
CONVECTION IS EXPECTED ONCE AGAIN DURING THE AFTERNOON
HOURS...WARRANTING AT LEAST A VCTS MENTION AT ALL TAF LOCATIONS.
CONVECTION WILL DISSIPATE AT DUSK...WITH SOME PATCHY FOG LIKELY
DEVELOPING ONCE AGAIN IN THE VALLEYS AFTER 06Z. SOUTHERLY WINDS
WILL PEAK IN THE 5 TO 10 KT RANGE THIS AFTERNOON...OTHERWISE WINDS
WILL REMAIN AT 5 KTS OR LESS.

&&

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

$$

UPDATE...GEOGERIAN
SHORT TERM...GEOGERIAN
LONG TERM...JMW
AVIATION...GEOGERIAN


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