Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 211450 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
1050 AM EDT THU AUG 21 2014

.UPDATE...
ISSUED AT 1050 AM EDT THU AUG 21 2014

14Z SFC ANALYSIS SHOW GENERAL LOW PRESSURE NORTH OF THE OHIO RIVER
WITH HIGHER PRESSURE FOUND TO THE SOUTH. A STATIONARY BOUNDARY EXISTS
THROUGH THE NORTHERN PORTIONS OF THE OHIO VALLEY AND WESTERN PARTS OF
THIS FRONT...CONNECTED BACK TO DEEPER LOW PRESSURE OVER THE NORTHERN
PLAINS...HAS BEEN A GENESIS REGION FOR RECENT MCS ACTIVITY. THIS
ACTIVITY IS ALSO SUPPORTED BY A STREAM OF MID LEVEL ENERGY RIDING
ALONG THE NORTHERN FRINGE OF A DEVELOPING RIDGE TO THE SOUTHWEST OF
KENTUCKY. THIS WOULD TEND TO SUPPORT CONVECTION WORKING SOUTHEAST
FROM THE UPPER MIDWEST TO THE CENTRAL APPALACHIANS PASSING BY JUST TO
OUR NORTHEAST. HOWEVER...INSTABILITY BUILDING WITH THE RECENT
ARRIVAL OF SUMMER TIME HEAT AND HUMIDITY ACROSS KENTUCKY WILL BE
ENOUGH TO KEEP A THREAT OF THE STORMS AND THEIR OUTFLOW BOUNDARIES
SNEAKING INTO NORTHEAST PORTIONS OF THE CWA AND PERHAPS FURTHER TO
THE SOUTHWEST IN THE AFTERNOON. THE CURRENT RADAR HAS A HEALTHY
CLUSTER OF STORMS CROSSING FROM INDIANA INTO OHIO WITH A GROWING
SOUTHERN EXTENT TRACKING THROUGH NORTHERN KENTUCKY. EXPECT THIS TO
BRUSH INTO NORTHERN PARTS OF THE FORECAST AREA THROUGH THE NEXT
SEVERAL HOURS. THE HRRR KEEPS THIS FIRST WAVE JUST NORTH OF THE
CWA...WHILE THE 12Z NAM12 DIPS THE CONVECTION DEEPER INTO EAST
KENTUCKY. FOR THIS UPDATE HAVE SPLIT THE DIFFERENCE BETWEEN THESE TWO
SCENARIOS AND PEAKED POPS IN THE NORTHEAST THROUGH THE AFTERNOON WITH
SOME SMALL TO MODERATE POPS EVEN DOWN INTO THE CUMBERLAND VALLEY BY
EVENING. HIGH PWS AND THE RAINS OF THE PAST SEVERAL DAYS WILL MEAN A
THREAT OF FLASH FLOODING FOR PLACES THAT SEE REPEATED STORMS...
PARTICULARLY THROUGH THE MID SECTION OF THE CWA. SPC HAS PLACED
EASTERN PARTS OF THE AREA...ALONG THE PREVIOUSLY DISCUSSED STORM
TRACK...IN A SLIGHT RISK FOR SEVERE WEATHER...MAINLY DAMAGING WINDS
AND LARGE HAIL. THIS APPEARS REASONABLE GIVEN THE HIGH CAPE...LOW
LIS...AND LACK OF A MID LEVEL CAP. ACCORDINGLY THIS CONCERN WILL
CONTINUE TO BE HIGHLIGHTED IN THE HWO ALONG WITH A MENTION OF THE
HEAT AND HUMIDITY...TEMPS NEAR 90 AND DEWPOINTS IN THE 70S...THROUGH
THE WEEKEND. HAVE ALSO FINE TUNED THE T AND TD GRIDS PER THE LATEST
OBS...TRENDS...AND CONSSHORT GUIDANCE. THESE UPDATES HAVE BEEN SENT
TO THE NDFD AND WEB SERVERS WITH NEW HWO AND ZONES ON THEIR WAY.

UPDATE ISSUED AT 757 AM EDT THU AUG 21 2014

THE FORECAST REMAINS ON TRACK THIS MORNING. FRESHENED UP THE HOURLY
TEMPERATURES...DEW POINTS...AND SKY COVER TO ACCOUNT FOR THE LATEST
TRENDS IN THE OBSERVATIONS.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 357 AM EDT THU AUG 21 2014

THE LATEST SURFACE MAP FEATURES HIGH PRESSURE ACROSS THE GULF COAST
STATES...WITH LOW PRESSURE ACROSS THE PLAINS STATES. A STATIONARY
BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE GREAT LAKES/OHIO
VALLEY REGION. ALOFT...AN UPPER LEVEL LOW CONTINUES TO SPIN ACROSS
THE NORTHERN GREAT LAKES...WITH AN UPPER LEVEL RIDGE CENTERED NEAR
THE NORTHERN GULF OF MEXICO...AND MORE TROUGHING FEATURED ACROSS
THE NORTHERN ROCKIES. SEVERAL COMPLEXES OF THUNDERSTORMS HAVE BEEN
GENERATING AND THEN RIDING SOUTHEAST ON THE PERIPHERY OF THE UPPER
LEVEL RIDGE OVER THE PAST FEW DAYS.

CURRENTLY...EASTERN KENTUCKY REMAINS QUIET AS ONLY A WEAKENING
SMALLER COMPLEX OF THUNDERSTORMS IS SLOWLY MOVING THROUGH SOUTHEAST
ILLINOIS AND SOUTHWEST INDIANA. THE NEXT MORE ORGANIZED COMPLEX IS
CURRENTLY MOVING THROUGH MINNESOTA.

THE MODEL GUIDANCE HAS BEEN ALL OVER THE PLACE WITH THE TIMING OF THE
MORE ORGANIZED CONVECTION AS OF LATE. AS SUCH...HAVE USED A GENERAL
BLEND OF THE GUIDANCE AND THE INHERITED FORECAST. AS THE UPPER LEVEL
RIDGE SLOWLY BUILDS INTO THE REGION THROUGH FRIDAY...IT WILL
GENERALLY NUDGE THE MCS TRACK FURTHER NORTHEAST...HOWEVER SINCE THERE
WILL BE PLENTY OF FUEL FOR THE STORMS AND A WEAK SYNOPTIC PATTERN IN
PLACE...CAN NOT RULE OUT OUTFLOW INFLUENCE FURTHER SOUTHWEST. SOME
STORMS COULD APPROACH SEVERE LIMITS...AND ISOLATED FLASH FLOODING
WILL ALSO BE A POSSIBILITY...ESPECIALLY WHERE STORMS CAN MOVE
PARALLEL TO ANY ESTABLISHED OUTFLOW BOUNDARIES. WILL HIGHLIGHT THESE
THREATS IN THE HWO. POPS WILL GENERALLY PEAK IN THE AFTERNOON HOURS
TODAY AND FRIDAY...WITH LESSER CHANCES DURING THE OVERNIGHT HOURS.

HIGHS TODAY WILL AVERAGE IN THE 85 TO 90 DEGREE RANGE...WITH AROUND
90 DEGREES EXPECTED FOR MOST LOCATIONS ON FRIDAY.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 357 AM EDT THU AUG 21 2014

THE EXTENDED PORTION OF THE FORECAST BEGINS ON FRIDAY NIGHT WITH A
WELL DEVELOPED MID LEVEL RIDGE CENTERED OVER THE MID WEST AND
LONGWAVE TROUGH ENTERING THE NORTHWEST WITH AN EXITING TROUGH OVER
THE NORTHEAST. THE MID LEVEL RIDGE AXIS EVENTUALLY SHIFTS EAST OVER
THE OH VALLEY BY MONDAY AS IT WEAKENS A BIT WITH THE APPROACHING
TROUGH OVER THE NORTHERN PLAINS AND THE TROUGH OVER THE NORTHEAST
EXITING INTO THE ATLANTIC. THIS PATTERN BASICALLY KEEPS THE RIDGE
OVER EASTERN KENTUCKY THROUGH THE REST OF THE EXTENDED.

WITH THIS PATTERN IN PLACE THROUGH SUNDAY...EASTERN KENTUCKY REMAINS
IN NORTHWEST FLOW WITH STILL A FEW MCS/S LIKELY POISED TO TRACK
SOUTHEAST INTO THE AREA FOR THIS WEEKEND. WHILE MODELS INHERENTLY
WILL HAVE TROUBLE TRACKING THEM...THE FIRST ONE SHOULD BE MOVING
THROUGH FRIDAY NIGHT WITH THE NEXT ONE POSSIBLY SATURDAY NIGHT. BY
SUNDAY...THE RIDGE AXIS REALLY BEGINS TO SET IN AND ADDITIONAL
STRONG CONVECTION MAY BE LESS LIKELY AND MAY BE MORE TIED TO DIURNAL
PROCESSES WITH A STATIONARY BOUNDARY ALONG THE EASTERN PORTION OF THE
CWA. BY MONDAY AND THROUGH WEDNESDAY...THE MID LEVEL RIDGE AXIS
MOVES OVER THE AREA WHICH SHOULD EFFECTIVELY CUT OFF CONVECTION...AT
LEAST DEEP CONVECTION. SOME AFTERNOON SHOWERS AND POSSIBLY A STORM OR
TWO MAY DEVELOP UNDER THE RIDGE. THE SOLUTION OF THE ALL MODEL BLEND
WOULD SUGGEST SOME UNCERTAINTY THERE WITH THE BEST CHANCE OF PRECIP
FRIDAY NIGHT THROUGH SUNDAY. THIS IS IN GOOD AGREEMENT WITH THE GFS
AND EURO AS WELL. OVERALL THE BROAD BRUSH OF POPS THROUGH THE FIRST 3
DAYS OF THE EXTENDED SEEMS NEEDED DUE TO THE NATURE OF THE MODELS
HAVING TROUBLE DEPICTING THE COMPLEXES MOVING THROUGH BUT DID GO WITH
SOME DIURNAL CHARACTERISTICS.

BY THE END OF THE EXTENDED...THE MODELS SEEM TO HINT AT THE RIDGE
MOVING FARTHER EAST AS A STRONG SHORTWAVE AND ASSOCIATED COLD FRONT
SEEMS POISED TO MOVE THROUGH THE MS RIVER VALLEY AND INTO THE OH
VALLEY. IN ADDITION...THE WARM AND MUGGY WEATHER STILL LOOKS TO BE
ON TAP THROUGH THE WEEKEND WITH HIGHS AROUND 90 THROUGH MONDAY AND
DEW POINTS AROUND 70. THE END OF THE EXTENDED DOES SHOW SOME RELIEF
FROM THE WARM AND HUMID WEATHER WITH THE APPROACH OF THE
AFOREMENTIONED COLD FRONT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 757 AM EDT THU AUG 21 2014

IFR OR WORSE FOG/STRATUS WILL DISSIPATE BY AROUND 13Z. SCATTERED TO
NUMEROUS CONVECTION WILL LIKELY THREATEN ONCE AGAIN FROM 16Z THROUGH
EARLY THIS EVENING. TIMING THIS ACTIVITY CONTINUES TO BE VERY
CHALLENGING SO WILL KEEP VCTS WORDING ONLY AT THIS TIME. SOME MVFR
OR WORSE FOG WILL LIKELY BE SEEN ONCE AGAIN AFTER 04Z TONIGHT. WINDS
OF AROUND 5 KTS OR LESS WILL REMAIN OUT OF THE SOUTHWEST THROUGH THE
PERIOD AS WELL.

&&

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

$$

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




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