Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 230742
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
342 AM EDT WED JUL 23 2014

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 342 AM EDT WED JUL 23 2014

SURFACE ANALYSIS ACROSS THE REGION AS OF 07Z FEATURE MOSTLY CLEAR
SKIES WITH SOME INCREASING CLOUD COVER OVER THE SOUTHEAST AS
SOUTHERLY MOIST FLOW CONTINUES TO MOVE INTO THE AREA. THIS IS AIDED
BY HIGH PRESSURE CENTERED OVER THE CAROLINAS. WITH DEW POINTS IN THE
LOWER 70S ACROSS MUCH OF THE AREA AND TEMPS ONLY DROPPING TO AROUND
70 FOR LOWS...MUGGY CONDITIONS WILL CONTINUE INTO DAWN AS WELL WITH
SOME FOG DEVELOPMENT IN THE VALLEYS. THIS FOG SHOULD DISSIPATE AS
CLOUD COVER INCREASES DURING THE MORNING HOURS.

HEADING INTO THE DAY...MODELS CONTINUE TO SHOW THE CLOSED LOW WILL
CONTINUE TO MEANDER ALONG THE LA/MS GULF COAST WITH A TROUGH AXIS
EXTENDING INTO THE CENTRAL APPALACHIANS AND WILL ASSIST IN SOME EARLY
DEVELOPMENT TODAY OF SOME SHOWERS AND THUNDERSTORMS. THIS WILL STILL
BE HINDERED WITH SOME MID LEVEL WARM AIR BUT THE CAP SHOULD BECOME
BUSTED IN SOME AREAS ALONG THE COUNTIES BORDERING VIRGINIA.
MEANWHILE...THE MUCH ANTICIPATED COLD FRONT WILL BEGIN TO IMPACT THE
AREA INTO THIS AFTERNOON. THE INCREASED FORCING AND SOUTHWEST FLOW
WILL ALLOW FOR INCREASED DEVELOPMENT DURING THE 18Z TO 00Z TIME FRAME
THIS AFTERNOON INTO THE EVENING. MODEL SOUNDINGS AGREE WITH A
DETERIORATING CAP THROUGH THE AFTERNOON...INCREASED LIFT...AND PWATS
IN THE 1.6 INCH TO 1.8 INCH RANGE WILL RAISE SOME CONCERN FOR SOME
CELLS WITH HEAVY RAINFALL AND A FEW DOWN BURSTS ACROSS THE AREA. ALSO
THERE IS STILL A 5% SEVERE RISK ACROSS THE AREA THIS AFTERNOON AND
INTO THE EVENING ISSUED BY SPC. SO WILL MENTION SOME STRONG STORMS IN
THE HWO WITH SOME HEAVY RAIN POTENTIAL AND POSSIBLY AN ISOLATED
DAMAGING WIND FROM A DOWN BURST. WILL KEEP LIKELY POPS BEGINNING THIS
AFTERNOON AND INTO THE EVENING CENTERED AROUND THE FORCING FROM THE
FRONT ITSELF. SINCE IT IS POSSIBLE THAT WITH THE MORNING CAP...THERE
MAY NOT BE ANY DEVELOPMENT AT ALL.

HEADING INTO TONIGHT...ASSISTED BY THE FRONT...PRECIP WILL CONTINUE
INTO TONIGHT WITH DIMINISHING CHANCES TOWARDS DAWN AS INSTABILITY
DECREASES. THE FORECAST CHALLENGE FOR THE PERIOD WILL BE HEADING INTO
LATE TONIGHT AND THURSDAY. MODELS HAVE THE FRONT PUSHING THROUGH BUT
THE HIGH PRESSURE TO THE EAST MAY HINDER THE APPROACH OF THE FEATURE
SO BRINGING AN END TO PRECIP MAY BE A BIT LATER ON THE DAY THURSDAY SO
WILL GO WITH A LOWER CHANCE BUT KEEPING CONFIDENCE RESERVED. A FEW
INSTANCES OF HEAVY RAIN MAY EXIST AFTER 06Z TONIGHT BUT THE SEVERE
THREAT...IF ANY SHOULD BE OVER. QUITE A COOLER AIR MASS EXISTS BEHIND
THIS FRONT WITH HIGHS IN THE UPPER 70S EXPECTED ON THURSDAY...NEARLY
10 DEGREES BELOW NORMAL. SO AN UNUSUALLY OVERALL COOL JULY CONTINUES.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 342 AM EDT WED JUL 23 2014

THE MODELS ARE IN A BIT BETTER AGREEMENT TONIGHT WITH RESPECT TO THE
PATTERN ALOFT THROUGH THE EXTENDED. THEY ALL DEPICT A STRONG RIDGE
OVER THE SOUTHWEST PART OF THE NATION AND A DEEP TROUGH OVER THE
NORTHEAST PART OF THE CONTINENT. THIS EASTERN TROUGH EXTENDS SOUTH
THROUGH THE APPALACHIANS TO THE GULF COAST KEEPING EAST KENTUCKY IN
A PROLONGED PERIOD OF NORTHWEST FLOW. HOWEVER...THE WESTERN RIDGE
DOES EXTEND EAST FOR A TIME ON FRIDAY SHIFTING THE SHORTWAVE TRACK
TO THE NORTH OF THE STATE AS HEIGHTS RISE LOCALLY. THIS RIDGE
QUICKLY RETREATS...THOUGH...SO THAT BY SATURDAY MORNING THE
NORTHWEST FLOW...AND ITS PERIODIC WAVES OF ENERGY...WILL AGAIN
ENGULF EAST KENTUCKY. THIS IS WHERE THE MODELS CONTINUE TO DISPLAY
THE DIFFERENCES THEY HAVE EXHIBITED FOR THE PAST 24 TO 48 HOURS. THE
PROBLEMS CENTER ON THE HANDLING OF THE WESTERN PART OF THE DEEP
NORTHEAST TROUGH AS IT SHIFTS SOUTHEAST AND INTO THE STATES. THE 00Z
GFS AND GEM CONTINUE TO BE QUICKER THAN THE 12Z ECMWF WITH THIS
DEVELOPMENT....BUT THE LATEST 00Z ECMWF HAS NARROWED THIS GAP. THIS
CONTINUES THE UNCERTAINTY ABOUT THE EXACT EVOLUTION PROCESS OF
THE TROUGH/S RENEWED SHIFT INTO THE GREAT LAKES AND OHIO VALLEY.
HOWEVER...THE END POINT IS FAIRLY CLEAR BY MONDAY MORNING AS ALL
MODELS ARE ON BOARD WITH AN UNSEASONABLY VERY DEEP AND LARGE TROUGH
PIVOTING THROUGH THE REGION. THE CORE OF THIS TROUGH DESCENDS WELL
SOUTH INTO THE GREAT LAKES AND OHIO VALLEY IN ALL THE MODELS...
THOUGH THE GFS ENDS UP BETWEEN 5 AND 10 DECAMETERS LOWER OVER THE
CWA BY TUESDAY EVENING OWING TO ITS MORE SOUTHERN CENTERING OF THE
TROUGH. THIS GYRE THEN STAYS BASICALLY PARKED OVER THE AREA WITH
ABNORMALLY LOW SUMMERTIME HEIGHTS THROUGH THE END OF THE EXTENDED.
GIVEN THE UNCERTAINTY WITH THE MID PART OF THE EXTENDED WILL NOT
DEVIATE FAR FROM A GENERAL MODEL BLEND AND CONTINUITY FOR THE
FORECAST.

SENSIBLE WEATHER WILL FEATURE A FAIRLY ACTIVE EXTENDED PERIOD WITH
TIMES OF STORMS...A THREAT OF HEAVY RAIN...AND MUCH COOLER
TEMPERATURES BY THE START OF NEXT WEEK. FOR THURSDAY NIGHT...SHOWERS
AND STORMS WILL CLEAR OUT TO THE EAST WITH A DEPARTING COLD FRONT IN
TIME FOR THE START OF THE EXTENDED. THIS WILL BE FOLLOWED BY 24 TO
36 HOURS OF DRY AND COOLER WEATHER BEFORE THE FRONT SURGES BACK
NORTH WITH PERIOD OF CONVECTION ANTICIPATED...NOT NECESSARILY
CONFORMING TO THE DIURNAL CYCLE SHOULD MCS ACTIVITY SET UP JUST
NORTHWEST OF THE CWA. WITH THIS...LOCALLY HEAVY RAIN WILL BE A
CONCERN SHOULD ANY ORGANIZED THUNDERSTORMS AFFECT THE SAME AREAS ON
CONSECUTIVE DAYS. AFTER A WEEKEND OF STORMY WEATHER BENEATH A QUASI
STATIONARY FRONTAL BOUNDARY AND AMPLE HEAT/HUMIDITY...A COLD FRONT
WILL LOOK TO SETTLE THINGS DOWN BY MONDAY EVENING AS IT DRIVES SOUTH
THROUGH THE AREA IN RESPONSE TO A FAIRLY DEEP SFC LOW MOVING THROUGH
THE EASTERN GREAT LAKES. COOLER WX ACCOMPANIES AND FOLLOWS THIS
FRONT WITH TUESDAY...POSSIBLY ENDING UP SIMILAR TO THE RECORD
SETTING COOLDOWN OF LAST WEEK...ESPECIALLY IF THE SKIES CLEAR QUICK
ENOUGH DURING MONDAY NIGHT AND STAY THAT WAY FOR TUESDAY NIGHT.

THE CR GRID LOAD PROVIDED A GOOD START TO THE FORECAST FOR THE
EXTENDED...THOUGH THE INGEST OF THE 12Z ECMWF HAS LIKELY HURT THE
CONSENSUS BLEND. ACCORDINGLY...DID ADJUST THE POPS TO HONE IN ON THE
PRIME CHANCES FOR CONVECTION OVER THE WEEKEND AND INTO MONDAY WITH
SPECIAL ATTENTION GIVEN TO THE ECMWF AND GFS SOLUTIONS. ALSO...
ADJUSTED THE LOW TEMPERATURE GRIDS A TAD TO REFLECT RIDGE AND VALLEY
DIFFERENCES THURSDAY AND FRIDAY NIGHT. FINALLY...WENT A BIT LOWER ON
MAXES AND MINS FROM MONDAY NIGHT THROUGH TUESDAY...FIGURING THE
MODELS ARE PLAYING CATCHUP ON THE UPCOMING UNSEASONABLE WX.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 139 AM EDT WED JUL 23 2014

SKIES ARE CLEARING OUT ACROSS THE AREA AND WITH SOUTHWESTERLY FLOW
BRINGING IN MOIST AIR...SOME FOG WILL DEVELOP IN THE MORNING HOURS.
TAF SITES SHOULD GO DOWN TO AT LEAST MVFR IF NOT SOME IFR TOWARDS
DAWN. JKL IS MORE LIKELY TO SOME VALLEY FOG ADVECTED IN ON STATION.
HEADING INTO THE DAY...CLOUD COVER WILL BE ON THE INCREASE AS A COLD
FRONT MOVES THROUGH. HAVE PUT THUNDER IN THE TAF SITES AND ON STATION
BY 19Z AS THE BEST CHANCE FOR THUNDERSTORMS WILL BE DURING THE
AFTERNOON TOWARDS THE EVENING WITH THE FRONT APPROACHING AS WELL.
MOST LOCATIONS SHOULD GO DOWN TO IFR CONDITIONS WITH THIS DURATION OF
PRECIP. CEILINGS SHOULD THEN BE IFR THROUGH THE REST OF THE TAF
PERIOD AS WELL. WINDS SHOULD BR LIGHT BUT INCREASE OUT OF THE WEST
WITH THE FRONT.


&&

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

$$

SHORT TERM...SHALLENBERGER
LONG TERM...GREIF
AVIATION...SHALLENBERGER





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