Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 121154 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
754 AM EDT SAT JUL 12 2014

.UPDATE...
ISSUED AT 748 AM EDT SAT JUL 12 2014

HOURLY GRIDS WERE FRESHENED UP BASED ON RECENT OBSERVATIONS AND
SATELLITE IMAGERY. OTHERWISE...THE CURRENT FORECAST IS ON TRACK. SFC
AND UPPER LEVEL RIDGING SHOULD BRING TO A WARM AND DRY DAY TO ALL
AREAS ONCE VALLEY FOG LIFTS AND DISSIPATE.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 405 AM EDT SAT JUL 12 2014

EARLY THIS MORNING...UPPER LEVEL RIDGING WAS CENTERED OVER THE PLAINS
STATES WITH RIDGING EAST INTO THE SOUTHEASTERN STATES AND ALSO WEST
AND NORTHWEST INTO THE DESERT SOUTHWEST AND NORTH INTO PARTS OF THE
INTER MOUNTAIN WEST. AN UPPER LEVEL LOW WAS CENTERED JUST WEST OF THE
HUDSON BAY REGION WITH SOME BROAD TROUGHING TO ITS SOUTH ACROSS PARTS
OF CENTRAL CANADA SOUTH INTO THE NORTH CENTRAL US AND NORTHERN GREAT
LAKES REGIONS. AT THE SFC...HIGH PRESSURE WAS CENTERED ALONG THE MID
ATLANTIC SEABOARD WITH THE RIDGE AXIS EXTENDING SOUTH INTO THE
SOUTHEASTERN STATES. EXTENDING SOUTH FROM SFC LOW PRESSURE OVER
CENTRAL CANADA WAS A COLD FRONT THAT DOWN SOUTH AND SOUTHWEST ACROSS
WESTERN LAKE SUPERIOR AND THEN FURTHER WEST AND SOUTHWEST INTO THE
NORTHERN PLAINS. MEANWHILE...THE REMNANTS OF A BOUNDARY THAT CROSSED
THE AREA EARLIER IN THE WEST EXTENDED FROM SFC LOW PRESSURE NEAR THE
LEE OF THE ROCKIES FIRST NORTH AND NORTHEAST INTO THE MID MS VALLEY
AND THEN SOUTH AND THEN SOUTHEAST ACROSS PARTS OF THE SOUTHEASTERN
STATES.

EARLY TODAY...MAINLY RIVER VALLEY FOG SHOULD GRADUALLY LIFT AND BEGIN
TO DISSIPATE WITHIN AND HOUR OR TWO AFTER SUNRISE. OVERALL...VIS
REDUCTIONS WITH THIS SHOULD BE LESS THAN ON FRIDAY AM.

TODAY AND TONIGHT...THE UPPER LEVEL LOW WILL DROP SOUTH AND THEN
SOUTHEAST INTO NORTHWESTERN ONTARIO BY DAWN ON SUNDAY. THIS WILL PUSH
THE INITIAL SFC COLD FRONT EAST MORE QUICKLY THAN SOUTH A RIDGING WILL
REMAIN IN PLACE FROM THE ROCKIES INTO THE SOUTHERN PLAINS AND
SOUTHEASTERN CONUS. THE SOUTHWESTERN PART OF THE BOUNDARY SHOULD
EVENTUALLY MERGE WITH THE OLD BOUNDARY ACROSS THE CENTRAL PLAINS AS A
SFC WAVE WORKS NORTHEAST FROM THE CENTRAL CONUS AND INTO THE GREAT
LAKES. THIS WILL ALSO SEND WHAT IS LEFT OF THE OLD BOUNDARY NORTHEAST
ACROSS THE AREA AS A WARM FRONT TONIGHT. THIS WILL USHER IN A RETURN
OF MUCH DEEPER MOISTURE LATE TONIGHT AND ESPECIALLY INTO SUNDAY.

THE UPPER LEVEL LOW SHOULD MOVE FURTHER SOUTH BY THE END OF TH PERIOD
AND LEAD TO FURTHER HEIGHT FALLS ACROSS THE GREAT LAKES AND LOCALLY.
DURING THIS PERIOD THE INITIAL COLD FRONT SHOULD REACH NEAR THE OH
RIVER BY THE END OF THE PERIOD. HOWEVER...A MORE POTENT FRONT WILL
ALSO DROP SOUTH INTO THE GREAT LAKES AND MIDWEST ALSO BY THE END OF
THE PERIOD. THE MOST ACTIVE WEATHER WITH THE LOWERING HEIGHTS AND
SHORTWAVES WORKING THROUGH THE FLOW SHOULD BE AFTER THE PERIOD. HOWEVER...
WITH INCREASING MOISTURE AND SOME SFC HEATING THE ATMOSPHERE WILL
BEGIN TO BECOME UNSTABLE ON SUNDAY AHEAD OF THE SLOW MOVING BOUNDARY.
THERE WILL ALSO BE SOME SLIGHT HEIGHT FALLS DURING SUNDAY AFTERNOON
AS WELL. SOME ISOLATED TO POSSIBLY SCATTERED CONVECTION IS
ANTICIPATED AT THAT POINT. SHEAR SHOULD BE GREATEST ACROSS THE FAR
NORTHWEST...BUT MODELS DIFFER IN THE DEGREE OF INSTABILITY. SPC HAS
PLACE THE FAR NORTHWEST CWA IN A SLIGHT RISK OF SEVERE THUNDERSTORMS
AND PENDING ON CONVECTIVE EVOLUTION THE SOUTHWEST END OF A PREFRONTAL
LINE OF STORMS MIGHT REACH THE FAR NORTHWEST CWA LATE IN THE PERIOD.
THE DEGREE OF INSTABILITY IN PLACE ACROSS THE NORTHWEST PART OF THE
AREA...WHEN A LINE POSSIBLY ARRIVES LATE ON SUNDAY WOULD DETERMINE
WHETHER ANY STRONG TO SEVERE STORMS WITH GUSTY WINDS BEING THE MAIN
THREAT WOULD OCCUR. IT WOULD SEEM HOWEVER IF ENOUGH INSTABILITY CAN
BE REALIZED THAT MONDAY WOULD BE THE DAY DURING THE ENTIRE FORECAST
PERIOD WHERE STRONG TO SEVERE THUNDERSTORMS WOULD BE MOST
PROBABLE...AHEAD OF A SHARPER FRONT AND STRONGER MID LEVEL SYSTEM.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 326 AM EDT SAT JUL 12 2014

THE MODELS WERE IN GENERAL AGREEMENT IN THE EXTENDED PERIOD. THE
WEATHER OF THE UPCOMING WEEK WILL FEATURE WIDESPREAD SHOWERS AND
STRONG TO POSSIBLY SEVERE THUNDERSTORMS SUNDAY NIGHT THROUGH MONDAY
EVENING. THE MODEL DATA ALL SUGGEST DECENT INSTABILITY...GOOD LOW
LEVEL MOISTURE FEED FROM THE SOUTH...AND SOME WIND SHEAR DURING THE
DAY ON MONDAY. THE TRIGGER FOR ALL THE EXPECTED SHOWER AND STORM
ACTIVITY WILL BE A SLOW MOVING AND FAIRLY POTENT COLD FRONT. SHOWERS
AND STORMS WILL BE MOST NUMEROUS AND STRONGEST DURING FRONTAL PASSAGE
MONDAY AFTERNOON AND EVENING...SHOULD THE LATEST MODEL SOLUTIONS PAN
OUT THAT IS. THE FRONT IS EXPECTED TO STALL OUT ALONG THE SPINE OF
THE APPALACHIANS MONDAY NIGHT...KEEPING A CHANCE OF RAIN IN THE
FORECAST THROUGH THE END OF THE DAY ON TUESDAY.

MUCH COOLER AND DRIER AIR WILL FILTER INTO THE REGION BEHIND THE
FRONT BEGINNING TUESDAY NIGHT. THIS NEW AIR MASS WILL CONTRIBUTE TO
WELL BELOW NORMAL TEMPERATURES FOR THIS TIME OF YEAR...WITH HIGHS
TOPPING OUT IN THE VERY COMFORTABLE MID TO UPPER 70S TUESDAY
WEDNESDAY AND THURSDAY. OVERNIGHT LOWS TUESDAY NIGHT AND WEDNESDAY
NIGHT SHOULD EASILY DROP INTO THE MID TO UPPER 50S ACROSS THE AREA
BENEATH PARTLY CLOUD SKIES. THE MERCURY SHOULD BE ABLE TO CLIMB A
BIT HIGHER TO END THE WEEK AS THE AIRMASS MODIFIES...WITH HIGHS
REACHING THE LOWER 80S ON FRIDAY. AFTER A DRY PERIOD DURING THE
MIDDLE OF THE WEEK...ANOTHER SHOT OF RAIN MIGHT BE IN THE OFFING
TOWARD THE END OF THE WEEK...AS A WEATHER SYSTEM PASSES BY TO OUR
SOUTH THURSDAY NIGHT THROUGH FRIDAY NIGHT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 750 AM EDT SAT JUL 12 2014

AFTER PATCHY AREAS OF MVFR OR LOCALLY LOWER VIS IN FOG IMPROVES AS
THE FOG LIFTS AND DISSIPATES...HIGH PRESSURE SHOULD BE THE DOMINANT
WEATHER FEATURE. VFR AND LIGHT WINDS ARE EXPECTED FOR MOST OF THE
PERIOD. THE EXCEPTION WILL BE THE INITIAL DISSIPATING VALLEY FOG AND
ANY VALLEY FOG LATE IN THE PERIOD...AFTER 6Z. CONFIDENCE IN ANY OF
THIS AFFECTING THE TAF SITES IS NOT HIGH ENOUGH JUST YET TO INCLUDE
ATTM.

.JKL WATCHES/WARNINGS/ADVISORIES...

&&

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

$$

UPDATE...JP
SHORT TERM...JP
LONG TERM...AR
AVIATION...JP





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